[jetjok]

While I disagree with Mr. Dye that anyone was being disrespectful in the previous thread, he is correct that our discussion on the merits of high speed taxi testing was O/T. So, lets continue the discussion in a more suitable format.

[ed. Mark - I doubt that you saw the posts that I saw late last night. Completely inaproppriate. But a new thread is a good idea. PFD]


I have never been to "Test Pilot' school, and have not stayed at a Holiday Inn Express, but.....I have seen several near and actual accidents due to attempts at high speed taxi tests.
There just seems to be no justifiable reason to high speed taxi without being ready to fly.
My .02....Others may disagree, and they can do whatever they want! Just not in my plane!
__________________

 

[f1rocket]

100% agree Mark. Messing around within the margins of the flight envelope, on the ground, in a new airplane, with little to no familiarity or experience, why do it? What is learned from a high speed taxi test?

Once you are sure your brakes are broken in and work, and you can control the airplane in a slow to moderate taxi, just go to the end of the runway and take off.

 

[pierre smith]

As one who has done both,....

...I wholeheartedly agree.

I did high speed taxi tests with my Cassutt, back in the early '70's without the cowl installed, because I "couldn't wait" after the long build. Well, the airplane became airborne unexpectedly, so I jerked the throttle back and landed five or six times but managed not to do any damage. Fortunately, I had several thousand TD hours and just finished a spraying season in those "hard-to-land" Agwagons and was on top of my game.

The problem is that pilots get on the runway with the mindset that "I'm NOT going to fly, just do fast taxi's." The problem arises when it really does fly, then the mindset must really quickly be changed to a "****, it's flying," under totally surprised circumstances in a hurry. It's a whole lot easier when your mind is set on flying and you continue the cadence and do so.

Best,

 

[ao.frog]

Another vote for no.

The EAA chapter here in Norway has for a long time adviced against high speed taxi-testing.

Maybe other chapter-members from other countries could chime in too? For example if the US chapter recommends the same thing?

As other have said, I can't see what you can gain on a high speed taxitest, which you already haven't gained by the slow speed taxitesting.
Well, maybe except that you're running a big risk about damaging your newly built airplane...

 

[Tony Spicer]

So who recommends a high-speed taxi?

Have a look at AC90-89A, chapter 2.

Then go here http://tinyurl.com/2g9xzpk and read #12.

When do you suppose the FAA and EAA will realize a high-speed taxi isn't a good idea? Probably a good idea to drag Joe Norris into this discussion to get a read on the current EAA philosophy on the matter.

Tony

 

[vic syracuse]

High speed taxi testing, or just high speed taxiing for that matter, is one of the most dangerous parts of the operating regime for an airplane, for it is neither at its optimum speed for an airborne vehicle, nor is it at its optimum speed for ground based operations. It becomes light on the wheels due to lift, which makes for reduced braking ability, and there is not full aerodynamic control authority, which makes corrections for gusts and/or cross winds quite marginal.
I have always been opposed to it, not only for the above-mentioned reasons, but for one already pointed out: if you are not in the mindset that you are going flying, then if and when you are presented with that scenario your mind is not totally prepared to react properly. Usually the results are not very pretty.

Vic

 

[Mel]

The most dangerous part of flying, especially a new untested aircraft, is take off and landing. Why would you want to investigate both these points simultaneously without recuperation time in between?

 

[Geico266]

The most dangerous part of flying, especially a new untested aircraft, is take off and landing. Why would you want to investigate both these points simultaneously without recuperation time in between?

EXACTLY right.

Well put Mel.


About the only "high speed taxi" I see necessary is to "season" or condition new brakes & rotors. Going about 25 MPH and brake firm to a stop a couple of times. This conditions the brake pads, breaks in the rotors, and assures control when braking if needed on the initial flight. Other than that high speed taxi runs are dangerous with little to nothing to be gained. The risk certainly does not justify the reward.

 

[TSwezey]

Well I don't see anything wrong with a short flight on a long runway. If anything is going to go wrong control or engine wise I would rather be at 5' going 65 knots than at 1,000' going 100 knots. Just my opinion and you can do whatever you want because it's your life that you are risking.

 

[Ironflight]

Have a look at AC90-89A, chapter 2.

Then go here http://tinyurl.com/2g9xzpk and read #12.

When do you suppose the FAA and EAA will realize a high-speed taxi isn't a good idea? Probably a good idea to drag Joe Norris into this discussion to get a read on the current EAA philosophy on the matter.

Tony

Interesting Tony - I hadn't gone back and read the second reference for awhile. It's a good thing that we have learned a lot in the 20 years since the EAA guidelines were written - now if we can just get them updated (I agree - a mission for Joe Norris). At least you can see that most of the EAA Flight Advisors responding here are against high speed taxi testing!

While I can agree to the argument that in some highly experimental flight test programs, with completely untried designs, taxi testing might be appropriate, for the kit planes we are all working on these days, I will never recommend it, and in fact vigorously recommend against it - for all the reasons given above.

 

[N8RV]

Several years ago, I was enjoying a nice, quiet evening at our small, uncontrolled airport. The only activity was a guy who had recently taken ownership of a small, underpowered homebuilt monoplane of some unknown variety. He was taxiing up and down the runway, apparently getting used to the ground handling characteristics.

However, after a half-hour or so, I noticed that the half-VW engine was spinning up a bit faster and watched him accelerate down the runway, lift off about 5-6 feet and chop the power, dropping back to the runway. Being clueless about homebuilding back then, I figured this was all part of the flight testing regimen.

Back and forth, he did this for about 20 minutes. I looked up just in time to see him climb a bit higher than he'd apparently expected -- about 10-12 feet -- and chopping the power resulted in a drop that required addition of more power. The ensuing PIO left him insufficient runway length to land, and he wisely elected to FLY.

His flight instructor and a gaggle of other airport bums assembled in my hangar (which faces the runway) as the plane disappeared behind some tall trees.

"He IS going to take it up to altitude and practice some slow flight before he tries to land, isn't he?" I asked his instructor.

The instructor just smiled and said, "Gentlemen, you're about to see the first and last landing of that airplane."

We watched as he reappeared from the trees, barely high enough to establish an approach to the runway. As he continued to slow, wobbling and drifting off the centerline, it was apparent that he may stall, which he did just off the end of the runway -- just at his right wing caught a lone tree.

He dropped the remaining 15 feet or so to the ground and the plane came to a sudden and complete stop. We hopped into my truck and raced to help, and luckily the pilot was OK. The plane was not.

I only taxied Smokey around a few times, getting used to the feel of a taildragger. When conditioning the brakes, that little story came to mind as I accelerated down the runway and hit the brakes.

Unless you're ready to fly -- REALLY ready -- there's far less to be gained than lost from high-speed taxi tests. If you just can't help yourself, wait until you're ready to fly and then give it a go if you must. But, as a newbie to TD with minimal transition training, I found that it was pretty much a non-event. Taxi enough to know if it tracks straight and true and then fly.

 

[apkp777]

When I was "taxi testing" my plane I rolled around the taxiways looking and listening for the obvious. I did one "run" down the runway at part power and just enough to get my airspeed to come alive (which failed on the first flight by the way). I was at this point considering doing my first flight with no transition training. After realizing that my -9 was not a docile 172, I immediately set up my 5 hours transition training (which I got before my first flight).

The problem with Tony B's article, is that it is generic. If you built a plane that has a 1000ft take off roll then by all means, get it going down the runway. An RV (-9 in particular) has such a short take off roll you really can't do a "high-speed" test without doing an unexpected flight. My plane is airborne in 4 seconds from the first application of power when light. That means 3 seconds for a "high speed" taxi. You will learn nothing in 3 seconds that will do you any good. A simple low speed taxi will tell you if you have ground handling problems.

As a flight instructor one of the more challenging maneuvers to teach a new student is the aborted takeoff. Much more difficult than an aborted landing. One day I was on downwind while one of my solo students was taking off. Of course, it's always nerve racking, but when I looked down she was spun around and off the runway. YIKES. She was fine, the plane was fine, but she goofed on her takeoff roll (had the yoke full fwd, wheel barreled it) tried to abort, got behind on the controls and ground looped a 152.

Point is, don't think its just a simple maneuver. When on my first flight my airspeed went TU, there was NO way I was going to abort. I wanted at least an hours worth of flight time before making my first landing, especially with no airspeed.

Just my thoughts, don't shoot me!

 

[claycookiemonster]

Hi speed tricycles

Has anyone noticed that those off-road trikes aren't sold anymore? Three wheels (regardless of how many lead and how many follow) and high speeds just don't seem to mix well.

 

[skylor]

High Speed Taxi, Prepared for Flight?

One issue that I have with people doing high speed taxi tests is that they are simply not planning to or prepared to fly. I know of several instances of builders doing multiple high speed taxis BEFORE they go through transition training, one of whom was a fairly high profile -8 builder earlier this year. This is evidence that they don't plan to fly the plane. Furthermore, I wonder (speculation here) how many of these same people don't even bother tightening down their shoulder straps for these tests since they obviously don't think they are going flying. Even taxi accidents without shoulder harnesses can result in serious injury or worse. Heck, I even pulled my shoulder straps tight before my first engine start, just in case my plane got loose.

The point that most people here have made here, as well as Van himself, is that there is little to be gained by high speed taxi testing our RV's, and since doing so may result in flight you better be darned well prepared to fly if you are going to do this. I think that some people do the taxi "tests" because they are just too anxious to wait until their real first flight to "play around" with their newly built plane. These are not toys!

Skylor
RV-8 N808SJ
Flying, 40 hours

 

[Toobuilder]

?High speed taxi testing? is a valid test point in military and commercial aircraft development. However, the preparation for this test series is exactly like the first flight ? the aircraft is in proper CG, fully assembled, fueled and preflighted ? it?s as ready to fly as it ever will be. Similarly, the pilot is briefed and prepared for flight ? just in case. In short, pilot and machine are ready for a flight, even though that is not the mission objective.

That said, despite the fighter pilot wannabes among us, the RV is not an F-35. High speed taxi is simply not a good idea for a sub 2000 pound aircraft that can be picked up and ?flown? with a puff of wind; and even if there is some meaningful data that can be gleaned from running up and down the runway with the tail up, it comes at an extremely high cost in the form of risk.

Build it right, get your head straight, go fly!

 

[jnorris]

I'm in Kansas City at meetings with the FAA (on amateur-built safety by the way) so I don't have a lot of time to respond. However, I will add this to the thread for now...

High-speed taxi tests should be approached with EXTREME caution, and the airplane AND pilot should be 100% ready to fly before even attempting high-speed taxi. The fact is, many pilots should not even attempt high-speed taxi testing because they are just not ready to deal with the possible "complications". We talk about this issue quite a bit during the SportAir Workshop flight testing course. As many posters in this thread have pointed out, high-speed taxi testing is probably the place with the most potential for disaster, as has been illustrated in two separate accidents this past week alone.

 

[f1rocket]

Well I don't see anything wrong with a short flight on a long runway. If anything is going to go wrong control or engine wise I would rather be at 5' going 65 knots than at 1,000' going 100 knots. Just my opinion and you can do whatever you want because it's your life that you are risking.

You are right about one thing......you can do whatever you want because it's your life. I would rather make my first landing with altitude and speed to spare so I can set myself up on a stabilized approach. What's the old saying about useless things.....runway behind you and altitude above you? To me, that seems to describe precisely what happens when a high speed taxi test goes wrong.

 

[Alan Carroll]

Have a look at AC90-89A, chapter 2.

Then go here http://tinyurl.com/2g9xzpk and read #12.

When do you suppose the FAA and EAA will realize a high-speed taxi isn't a good idea? Probably a good idea to drag Joe Norris into this discussion to get a read on the current EAA philosophy on the matter.

Tony

To look at the other side of this debate, I suspect that when Tony Bingelis wrote his flight test recommendations (21 years ago) he had in mind a much broader mix of aircraft, many of which were plans built. The justification for doing high-speed taxiing seems to have been to detect grossly out of trim aircraft that may in fact not have been capable of safe flight off the runway. Doesn't seem like such a crazy idea in that context, although it does suggest the need for a test pilot with well above average qualifications.

The RVs don't really fit this description at all. Since the design itself is well tested, it would presumably require some rather drastic construction errors to produce an unflyable example.

 

[N131RV]

Experience

I learned a tough lesson doing "taxi testing" back in 2003 in a Murphy Rebel.

Because I wanted to avoid flight, I lost my major escape route when something went wrong.

I was doing "tail up, hold it, tail down" tests, about 40 - 45 knots. On one "tail down", the tail spring delaminated and kicked the tail hard right. Had I been ready to fly, the escape was right there, put in power, raise tail, and fly. Then come around and do a wheeler and hold that tail up as long as possible. I might still loop, but probably at about 20 mph instead of 45 mph and I'd be prepared for it.

Instead, I ended up doing a fast ground loop with a fair amount of damage. No injuries fortunately.

My personal opinion, if it ain't ready to fly, it ain't ready to taxi at more than a walk.
And especially, if the pilot is not "ready to fly", then high speed taxi testing is an invitation to something bad happening.
YMMV

 

[rv6ejguy]

I respect the opinions and concerns expressed here however I'd like to make a few observations.

First, if you are planning these tests on less than 2500 feet or runway- don't. There are too many ways for this to go wrong.

I would not assume that all RVs will react the same way. Assumptions are a bad idea in test flying. There would be no need for test flying if every airplane reacted the same way.

In my case, I did at least 30 high speed taxis prior to first flight. Good thing I did as at about 35 knots I had a SEVERE gear leg vibration which felt like it would rip the gear off the aircraft. It took several tries with ground observation and different stiffeners and dampers to solve this.

I also thought it was valuable at see how the unproven propeller, engine and turbo combination worked when rolling up to 40 knots. Maybe this applies less on a Lycoming powered RV but I know of prop governor problems which have been uncovered during fast taxi tests.

Fast taxi can give you an opportunity to cross check the ASI with the GPS and confirm that the ASI even works. A no wind day is best for this and in fact for ALL fast taxi testing.

Fast taxi testing can give you a feel for throttle and rudder response too. Again, valuable IMO.

If you can't watch the ASI and cut the throttle at your safe point (say 35-45 knots), you should not be be in the seat for any test flying IMO. I never even came close to getting airborne in any of my testing.

I would say that fast taxiing A models (on hard surfaces) is probably safer than repeated tests on a taildragger RV.

I don't agree that valuable things cannot be learned during this phase. It seems here than many assume or hope that nothing in particular can or will go wrong in the 0-60 knot phase.

My list for test flying including fast taxi testing:

1. Everything needs to be ready for actually flying- C of G, insurance, no missing parts, seat belts fastened, pilot currency etc.

2. Long, wide, hard surface runway, calm conditions. Don't use an airport surrounded by high terrain, trees or buildings- lots of people have been killed by the poor choices in airports when the engine stopped and they have no real options for a forced landing.

3. Every flight or test should have a pre-planned goal in writing, on your kneepad. Go over this and stick to it.

4. Pay attention to runway remaining and have a speed and runway remaining cutoff point firmly in your mind. Never exceed these safety limits.

5. Never get in the mindset that you are committed the takeoff. Things can go wrong on the roll and aborting is often the best option.

Many of these accidents come down to a cavalier attitude, unpreparedness and a lack of general thought. None of these belong in any test flying program. I don't blame the exercise as much as the guy holding the stick making bad decisions- the leading cause of most aviation accidents.

 

[L.Adamson]

I respect the opinions and concerns expressed here however I'd like to make a few observations.

First, if you are planning these tests on less than 2500 feet or runway- don't. There are too many ways for this to go wrong.

I would not assume that all RVs will react the same way. Assumptions are a bad idea in test flying. There would be no need for test flying if every airplane reacted the same way.

In my case, I did at least 30 high speed taxis prior to first flight. Good thing I did as at about 35 knots I had a SEVERE gear leg vibration which felt like it would rip the gear off the aircraft. It took several tries with ground observation and different stiffeners and dampers to solve this.

I also thought it was valuable at see how the unproven propeller, engine and turbo combination worked when rolling up to 40 knots. Maybe this applies less on a Lycoming powered RV but I know of prop governor problems which have been uncovered during fast taxi tests.

Fast taxi can give you an opportunity to cross check the ASI with the GPS and confirm that the ASI even works. A no wind day is best for this and in fact for ALL fast taxi testing.

Fast taxi testing can give you a feel for throttle and rudder response too. Again, valuable IMO.

If you can't watch the ASI and cut the throttle at your safe point (say 35-45 knots), you should not be be in the seat for any test flying IMO. I never even came close to getting airborne in any of my testing.

I would say that fast taxiing A models (on hard surfaces) is probably safer than repeated tests on a taildragger RV.

I don't agree that valuable things cannot be learned during this phase. It seems here than many assume or hope that nothing in particular can or will go wrong in the 0-60 knot phase.

My list for test flying including fast taxi testing:

1. Everything needs to be ready for actually flying- C of G, insurance, no missing parts, seat belts fastened, pilot currency etc.

2. Long, wide, hard surface runway, calm conditions. Don't use an airport surrounded by high terrain, trees or buildings- lots of people have been killed by the poor choices in airports when the engine stopped and they have no real options for a forced landing.

3. Every flight or test should have a pre-planned goal in writing, on your kneepad. Go over this and stick to it.

4. Pay attention to runway remaining and have a speed and runway remaining cutoff point firmly in your mind. Never exceed these safety limits.

5. Never get in the mindset that you are committed the takeoff. Things can go wrong on the roll and aborting is often the best option.

Many of these accidents come down to a cavalier attitude, unpreparedness and a lack of general thought. None of these belong in any test flying program. I don't blame the exercise as much as the guy holding the stick making bad decisions- the leading cause of most aviation accidents.

Thank you Ross,

IMO, there is a bit too much of "don't do it under any circumstances" in this thread. This plays well with a previous thread in which it was pointed out that we're fools to do our own first test flight, and that some "test" pilot should do it.

I did do one test run to 45 kias. I was totally preparred to fly, and wouldn't have done it otherwise. The runway is wide and a mile and a half long. I was most interested in tracking and indicated air speed. The next run was a few orbits over the airport, followed by a cowl removal checkout; and then a flight of over one hundred miles (each way) which took me away from dense subdivisions, and out over the open freeway & desert.

Point is, it doesn't always have to be....... never do a high speed taxi test, and never test fly your own aircraft. Circumstances greatly vary between the builder/ pilots and airport being used. It's not a case of one formula fits all..

L.Adamson --- RV6A

 

[jetjok]

Have a look at AC90-89A, chapter 2.

Then go here http://tinyurl.com/2g9xzpk and read #12.

When do you suppose the FAA and EAA will realize a high-speed taxi isn't a good idea? Probably a good idea to drag Joe Norris into this discussion to get a read on the current EAA philosophy on the matter.

Tony

I did not research the AC that you cited, but did go to the EAA 365 site. I thought it might be helpful if our members could see what #12 stated about high-speed taxi testing. You will note that even the EAA emphasizes that high speed taxi testing can go very wrong...very fast. Additionally, keep in mind that much of #12 is likely written for those who have not constructed an aircraft that is match drilled, and/or partially assembled, and has been well flight tested by the manufacturer.

12. HIGH SPEED TAXI TESTS ? The real purpose for high speed taxi testing is to learn how the airplane feels and behaves just before reaching lift off speed.

For safety's sake, select an abort reference point (marker) about halfway down the runway. You should be able to cut your power when you reach that point and still have sufficient runway left for a safe stop without burning up the brakes and tires.

High speed runs down the runway must be limited to approximately 10 mph below anticipated lift-off speed.

Control effectiveness can be readily determined within that speed limitation. All flight controls, even the ailerons, normally become effective at relatively low speeds. You should, therefore, be able to work the controls to determine whether or not they are operating properly . . . and do so without trying one of those kamikaze lift-offs.

"Controlled lift-offs", particularly down a runway that is less than 5000 feet long, are dangerous and should not be attempted by inexperienced test pilots.

High speed taxi runs can also be helpful in verifying your weight and balance estimates. For example, if the tail is difficult to raise (taildragger) at moderate runway speeds, you probably have a tail heavy (aft CG) weight and balance situation. Return to the ramp and recheck the weight distribution and your figures again. Correct the problem.

Similarly, with a tricycle gear airplane, try raising the nosewheel after the elevator becomes effective. If you can't pick up the nosewheel at a fairly high taxi speed, you may likewise have a weight and balance problem . . . a forward CG condition. The proper technique is to get up to speed (10 mph below estimated take-off speed) - cut the throttle and check for rotation. This will save you the embarrassment of an accidental kangaroo take-off.

Make a couple of runs with and without a partial deployment of flaps. Is there a noticeable difference?

Pay attention to the amount of rudder input that is necessary to counteract engine torque and to keep the airplane straight on the runway. Watch out for fast applications of throttle at low speeds.

VW engines generally rotate opposite to the Lycomings and Continentals so be prepared to use left rudder on takeoff for torque correction.

Glance at your airspeed indicator during the high speed runs to see that it is working.

Monitor fuel and oil pressures, oil temperature and, also, the cylinder head temperature. If any of the indications are suspect, return to the ramp immediately.

Keep the tailwheel on the ground, with stick back pressure, at low runway speeds (taildraggers) until rudder effectiveness is obtained (about 30 mph) . . . especially in crosswind conditions. Likewise be very careful when the throttle is reduced after a high speed tail high taxi run and the tail starts to settle. Inadvertent back pressure on the control stick (too soon and too quick) might cause a surprise lift-off and difficult runway control problems.

NOTE - Complete each of the following component and system checks even if you know you have previously accomplished them prior to certification.

There are numerous references to erroneous W&B data contained in EAA #12, and I question how an RV builder could make such a mistake? With so many RV's of each model flying, there is much data available about what the nominal EW and CG of each respective model should be. Therefore, if your calculations are an anomaly to the mean data, you had better do some investigating long before your plane leaves the hangar.
In my past life, I was tasked with doing many W&B calculations on both spam cans, and experimental aircraft (Pitt Specials). We always made it a point to have more than one person reading each weight, and then we would retire to separate tables to work up the calculations. That way, there were no distractions and no one person influencing the others.
One last personal thought. The EAA states that taxi tests should be made to within "10 MPH of anticipated lift off speed". I submit it would be more accurate to be within 10 MPH (9 KT) of anticipated Vs for your aircraft. Once again, all this data is readily available, and seems to be a more definitive value.

 

[Mike S]

I'm in Kansas City at meetings with the FAA (on amateur-built safety by the way) so I don't have a lot of time to respond. However, I will add this to the thread for now...

Sent you a PM.

 

[Toobuilder]

I respect the opinions and concerns expressed here however I'd like to make a few observations.

First, if you are planning these tests on less than 2500 feet or runway- don't. There are too many ways for this to go wrong...

If you MUST fast taxi for some reason, I agree with the premise that bigger runways are better...

I would not assume that all RVs will react the same way. Assumptions are a bad idea in test flying. There would be no need for test flying if every airplane reacted the same way..

True, but a little misleading... A properly built kit aircraft will be substantially similar in handling than any other. The "test" should be much more of a "verification". We certainly have post maintenance flights for military aircraft, but I assure you, the pilot is not wondering "if" the aircraft will fly - only that it functions properly. I'm sure the Cessna "test" pilots have little trepidation when they fly a new 172 for the first time as well. The takeaway here is that a properly built RV is very likely to fly, if there are problems, it's far better to sort them out at 500-1000 AGL with you head in "pilot mode" than departing the side of the runway at 60 knots with your head in "taxi test mode".

In my case, I did at least 30 high speed taxis prior to first flight. Good thing I did as at about 35 knots I had a SEVERE gear leg vibration which felt like it would rip the gear off the aircraft. It took several tries with ground observation and different stiffeners and dampers to solve this..

This sounds like an unusual condition that should have caused a aborted takeoff at worst. Still quite flyable though.

I also thought it was valuable at see how the unproven propeller, engine and turbo combination worked when rolling up to 40 knots. Maybe this applies less on a Lycoming powered RV but I know of prop governor problems which have been uncovered during fast taxi tests..

This could also have been found with a ground run if it was that far out of adjustment. If it was a just little out, flight would have been appropriate - or at the least, lower risk than hurtling down the runway.

Fast taxi can give you an opportunity to cross check the ASI with the GPS and confirm that the ASI even works. A no wind day is best for this and in fact for ALL fast taxi testing..

Again, easily cheked on the ground without even starting the engine...

Fast taxi testing can give you a feel for throttle and rudder response too. Again, valuable IMO..

...Extremely low value data - at high risk. Push right, go right - throttle on or off.... What's the point?

If you can't watch the ASI and cut the throttle at your safe point (say 35-45 knots), you should not be be in the seat for any test flying IMO...

True, but why force yourself to perform this task on your first experience with the airplane?

I never even came close to getting airborne in any of my testing..

Your experience differs from many others including the pilot of the YF-16 on his "high speed taxi" test.

I would say that fast taxiing A models (on hard surfaces) is probably safer than repeated tests on a taildragger RV..

"Safety" is relative. High speed taxi is still a demonstrated high risk behavior.

I don't agree that valuable things cannot be learned during this phase. It seems here than many assume or hope that nothing in particular can or will go wrong in the 0-60 knot phase..

Perhaps, but I have no idea what they are when compared to the risk posture.

My list for test flying including fast taxi testing:

1. Everything needs to be ready for actually flying- C of G, insurance, no missing parts, seat belts fastened, pilot currency etc.

2. Long, wide, hard surface runway, calm conditions. Don't use an airport surrounded by high terrain, trees or buildings- lots of people have been killed by the poor choices in airports when the engine stopped and they have no real options for a forced landing.

3. Every flight or test should have a pre-planned goal in writing, on your kneepad. Go over this and stick to it.

4. Pay attention to runway remaining and have a speed and runway remaining cutoff point firmly in your mind. Never exceed these safety limits.

5. Never get in the mindset that you are committed the takeoff. Things can go wrong on the roll and aborting is often the best option.

Many of these accidents come down to a cavalier attitude, unpreparedness and a lack of general thought. None of these belong in any test flying program. I don't blame the exercise as much as the guy holding the stick making bad decisions- the leading cause of most aviation accidents.

On this I agree.

 

[rv6ejguy]

Thank you Ross,

IMO, there is a bit too much of "don't do it under any circumstances" in this thread. This plays well with a previous thread in which it was pointed out that we're fools to do our own first test flight, and that some "test" pilot should do it.

I did do one test run to 45 kias. I was totally preparred to fly, and wouldn't have done it otherwise. The runway is wide and a mile and a half long. I was most interested in tracking and indicated air speed. The next run was a few orbits over the airport, followed by a cowl removal checkout; and then a flight of over one hundred miles (each way) which took me away from dense subdivisions, and out over the open freeway & desert.

Point is, it doesn't always have to be....... never do a high speed taxi test, and never test fly your own aircraft. Circumstances greatly vary between the builder/ pilots and airport being used. It's not a case of one formula fits all..

L.Adamson --- RV6A

Yep, pretty much sums it up in a nutshell.

 

[TSwezey]

You are right about one thing......you can do whatever you want because it's your life. I would rather make my first landing with altitude and speed to spare so I can set myself up on a stabilized approach. What's the old saying about useless things.....runway behind you and altitude above you? To me, that seems to describe precisely what happens when a high speed taxi test goes wrong.

If you can't take off and land on 10,000' of runway you should be doing a test flight. We did ours at an airport that probably ranks up in the top ten number wise for first flights. You are also assuming your engine is well tested and proven. I wish we would have done more high speed taxiing test and we would have found the wiring issue that trashed our engine. It's not a one size fits all! It's just like everybody saying if you are a VFR pilot you will die within seconds of entering a cloud. Everybody and every plane are not the same. Certain conditions can dictate that you do not follow the same path as everybody else. As everyone says and I agree you should be 100% ready to fly away from the airport before you do this.

 

[Mike S]

Circumstances greatly vary between the builder/ pilots and airport being used. It's not a case of one formula fits all..

L.Adamson --- RV6A

Just consider how many subjects/threads that statement totally applies to.

 

[David Paule]

"For example, if the tail is difficult to raise (taildragger) at moderate runway speeds, you probably have a tail heavy (aft CG) weight and balance situation. "

Probably not. Before attempting anything like this, you'd have certainly verified that the CG is in the correct range for a test flight. That's one of the prerequisites, after all.

What it shows if the tail is hard raise or if the nose is hard to lift, is that either the trim is not set right or you're not going fast enough yet for elevator control to become effective. And in most nosedraggers, you can verify the elevator during the run-up, so there's no need for a high-speed taxi just for that.

How about training? Before climbing aboard for this, it might be worth running through the test card in another airplane, one that you know well, for practice. If that seems especially risky, then imagine the risk of doing it without practice in an unproven airplane.

Now for a brief editorial:

There's one major thing that can get you killed, flying, and that's running into something. Inasmuch as there's a whole planet actually touching your airplane when trying a high-speed taxi, the opportunity to run into it is higher than at altitude. Simple, isn't it?

 

[rv6ejguy]

If you MUST fast taxi for some reason, I agree with the premise that bigger runways are better...

True, but a little misleading... A properly built kit aircraft will be substantially similar in handling than any other. The "test" should be much more of a "verification". We certainly have post maintenance flights for military aircraft, but I assure you, the pilot is not wondering "if" the aircraft will fly - only that it functions properly. I'm sure the Cessna "test" pilots have little trepidation when they fly a new 172 for the first time as well. The takeaway here is that a properly built RV is very likely to fly, if there are problems, it's far better to sort them out at 500-1000 AGL with you head in "pilot mode" than departing the side of the runway at 60 knots with your head in "taxi test mode".



This sounds like an unusual condition that should have caused a aborted takeoff at worst. Still quite flyable though.



This could also have been found with a ground run if it was that far out of adjustment. If it was a just little out, flight would have been appropriate - or at the least, lower risk than hurtling down the runway.



Again, easily cheked on the ground without even starting the engine...



...Extremely low value data - at high risk. Push right, go right - throttle on or off.... What's the point?



True, but why force yourself to perform this task on your first experience with the airplane?




Your experience differs from many others including the pilot of the YF-16 on his "high speed taxi" test.



"Safety" is relative. High speed taxi is still a demonstrated high risk behavior.



Perhaps, but I have no idea what they are when compared to the risk posture.




On this I agree.

I'm not sure you read and understood what I wrote at all.

This is not a black and white subject IMO. It's like saying we should not perform stall testing because some people get killed doing this. Nonsense.

First, my aircraft did not react "substantially the same" as others. There was no way I was going to push on with the takeoff and maybe watch the airplane disintegrate. I then had to do repeated tests to get the problem licked. It was quite persistent and hard to solve. There was nothing out of rig. All legs were drilled by Vans and it was all straight. Could not have be discovered without actually running down the runway. This is why we test.

I totally disagree with your assertion that is is better to deal with an issue in the air that you might discover on the ground. If you can't keep an airplane on the runway, you shouldn't be in the pilot's seat to begin with.

I also disagree that all propeller issues can be sorted out in a static run. Not in the case of electric props or unknown combos. As speed builds, and the prop unloads, issues can surface such as motor/ pitch rate changes, pitch stop settings- no benchmarks. Fast taxi prepared me later in the program when a blade change was made which did not work out well.

The airplane won't fly at 40 knots so I don't buy this risk thing at all. These accidents almost always come down to pilot errors in judgement or skill- even experienced pilots have been bitten by getting carried away on the speed. I think the inadvertent flight of a restored Victor in the UK a couple years ago was probably the most spectacular. Fortunately they got back down safely but with many questions to answer. Clearly from the photos, they were not fully prepared to fly.

I think the mindset that you are taking off anyway is potentially more dangerous.

My aircraft is substantially different FF and in operation from most other RVs. There was no existing benchmark. Testing involves incremental increases in speed. While it may be true that most Lyco/ RVs fly substantially the same, respectfully, this does not apply to ALL RVs.

For people that fly non- standard RVs like Todd and me, we see the value in this sort of testing, from a perspective that few others here can appreciate perhaps. I'm not sure how many people here have experience with liquid cooled, turbocharged, geared automotive engines driving an electrically controlled prop?

This discussion is useful but in the end, each of us must decide if certain testing is in our best interest.

 

[Toobuilder]

...This discussion is useful but in the end, each of us must decide if certain testing is in our best interest...

I agree, but this is true of any endeavor. However, the decision must be made with due regard to risk vs. reward, rather than as a casual, arbitrary course of action. For example, you might have some valid reasons for your high speed taxi test, but if so, in my opinion you are the exception on this board filled with (if you?ll excuse the term) ?cookie cutter? airplanes. I suspect that if held to a true safety review board standard, many builders? arguments for high speed taxi look pretty weak - I?ll bet the true underlying reason for most high speed taxi testing is simply because it?s ?cool? to say you?re at a new milestone in the project. I still stand by my assertion that very little can be learned from high speed taxi that can?t be found by some other, safer, means.

Taking an even wider view, the danger with the ?test? mentality often seen on this board, (whether it?s taxi, a ?short hop? down the runway, or the first 40 hours) is that builders believe this is the time to ?uncover problems? or "work out the bugs". As a professional aircraft maintainer, I say BS! The time to ?uncover the problems? is in the hangar, before the engine is started or the panel is lit for the first time. Aside from an act of God, a problem in flight is a ?failure? ? either of the design, materials, or your skill as the manufacturer. As I have said many times before, if you even think you might have a problem, the aircraft is un-airworthy? Simply put, ?flight test? of a familiar aircraft really is to ?verify? what you, as the builder, should already know ? that the aircraft and systems function properly.

Anyway, I'm not real black and white on the issue. Meaning, I know that high speed taxi does not mean instant death, but people should not take it lightly either. High speed taxi is close to, and sometimes results in, flight. If you must do high speed taxi because it is the only reasonable method of gathering required data, then at least make sure the airplane and pilot are ready for a trip around the pattern.

 

[rv6ejguy]

I agree, but this is true of any endeavor. However, the decision must be made with due regard to risk vs. reward, rather than as a casual, arbitrary course of action. For example, you might have some valid reasons for your high speed taxi test, but if so, in my opinion you are the exception on this board filled with (if you’ll excuse the term) “cookie cutter” airplanes. I suspect that if held to a true safety review board standard, many builders’ arguments for high speed taxi look pretty weak - I’ll bet the true underlying reason for most high speed taxi testing is simply because it’s “cool” to say you’re at a new milestone in the project. I still stand by my assertion that very little can be learned from high speed taxi that can’t be found by some other, safer, means.

Taking an even wider view, the danger with the “test” mentality often seen on this board, (whether it’s taxi, a “short hop” down the runway, or the first 40 hours) is that builders believe this is the time to “uncover problems” or "work out the bugs". As a professional aircraft maintainer, I say BS! The time to “uncover the problems” is in the hangar, before the engine is started or the panel is lit for the first time. Aside from an act of God, a problem in flight is a “failure” – either of the design, materials, or your skill as the manufacturer. As I have said many times before, if you even think you might have a problem, the aircraft is un-airworthy… Simply put, “flight test” of a familiar aircraft really is to “verify” what you, as the builder, should already know – that the aircraft and systems function properly.

Anyway, I'm not real black and white on the issue. Meaning, I know that high speed taxi does not mean instant death, but people should not take it lightly either. High speed taxi is close to, and sometimes results in, flight. If you must do high speed taxi because it is the only reasonable method of gathering required data, then at least make sure the airplane and pilot are ready for a trip around the pattern.

I can't agree with your first statement and wonder what the problem is to stay on the centerline of a long, wide runway and pull the throttle back at 40 knots? Again, if you can't do this, back to flight school for you and you have no business actually getting into the air. Every flight involves the first part. A 6 or 7 cannot lift off at 40 knots in calm conditions. All aircraft manufacturers do fast taxi tests on new designs- they must have good reasons for this. I'm not a fan of the hop in ground effect. Your bet that "it's cool" is dead wrong. Sorry to disappoint but I try to approach testing and flying in a measured, professional manner. I'm trying to learn, not impress anyone. I've never even done a low pass in my RV so my ego quotient is pretty low I think.

I generally agree with your second paragraph but at the same time it shows a lack of understanding about new designs which have no track record. Not certified, not the same as many others, not proven. Most manufacturers uncover some issues in testing which need rethinking, or redesigning. This includes all types of devices like electronics, aircraft, cars etc. At some point, the engineering and manufacturing is complete to the best of our abilities and it is time to validate the design. I absolutely agree with you that is is foolish to try and fly if anything is even remotely suspect in your mind.

People shouldn't take ANY part of flying lightly and the care should not end after the magic 25 or 40 hours is flown off. Taxi by definition does not involve flight and taking the speed up to near rotation speed increases your chances of an inadvertent liftoff. Nobody ever lifted off for long at a speed well below stall speed. And I'll agree again with you that you should be prepared for flight every time you taxi out- I said that first time I commented here. The big problems come when you are not prepared for flight for sure.

Of course I had confidence that my 6A would fly when I rotated at 70 knots the first time. It was many other things out front that that were on my mind on the first flight.

I think these discussions about taxi and flight testing go back to stats and knee jerk reactions. This thread started right after the fatal flip over on an A model. Plenty of RVs of all types have flipped over and departed the runway during slow taxi, fast taxi and normal flight operations. More diligence and training could probably prevent most of these incidents. We should always be cautious about any activity which shows statistically higher risks and learn from other people's mistakes if we can.

Years ago the MU2 was branded as a dangerous aircraft after many crashes and incidents. In the last 5-10 years, its safety record has been quite good due to required proper training and flight procedures. It was never the aircraft or the action of flying it, simply the pilots doing things which they shouldn't have been doing.

I'm not saying that everyone should do fast taxi tests at all, just that they have been valuable for me and I'll do them again in my RV10 next year on a 5000 foot runway.

 

[Toobuilder]

...I can't agree with your first statement and wonder what the problem is to stay on the centerline of a long, wide runway and pull the throttle back at 40 knots? Again, if you can't do this, back to flight school for you and you have no business actually getting into the air...

My response to this is simply the long list of "fast taxi tests" that have turned into "flights" and sometimes "crashes". This list is composed of highly skilled test pilots in structured flight test programs as well as first time builders.

...And, have you ever performed a high speed taxi in a high powered tailwheel aircraft?

 

[L.Adamson]

...And, have you ever performed a high speed taxi in a high powered tailwheel aircraft?

I'll ask my hangar partner what he did. It's a Pitt's M-12 with the Russian radial.

L.Adamson ---- RV6A

 

[BobK]

Plane flipping

I was building a velocity and when complete a fast taxi was needed. Itr was heavier and took more runway but the need was to see if the controls were done correctly and there was no adverse effect on the plane. The method shown there was to pull the power at stall speed and then pull the stick back. The ground affect will lift the nose off for a few seconds allowing you to check the controls and such. It was also recommended to do a fast taxi to set the brakes. On an Rv were the speed builds up quickly, more caution would be needed.

Bob

 

[Toobuilder]

I'll ask my hangar partner what he did. It's a Pitt's M-12 with the Russian radial.

L.Adamson ---- RV6A

...One of my dream airplanes!

Anyway, not meant to imply it can't be done, but often a hard acceleration followed by a throttle chop causes a pretty good swing. It can be a little spooky in some airplanes even if you are ready for it. "Regular" landings are often much easier than the throttle chop... This point can be lost on people without TW time.

 

[rv6ejguy]

My response to this is simply the long list of "fast taxi tests" that have turned into "flights" and sometimes "crashes". This list is composed of highly skilled test pilots in structured flight test programs as well as first time builders.

...And, have you ever performed a high speed taxi in a high powered tailwheel aircraft?

I guess this shows that even highly skilled test pilots can make mistakes especially when they don't follow the plan. Maybe better to find out that something isn't right at low speed with the wheels on the ground than takeoff and try to deal with it on landing.

Nope, no useful tail wheel, aerobatic or night training time so I avoid all 3 activities in single engined aircraft as PIC.

It is indeed interesting how we each evaluate risk differently in flying.

 

[Toobuilder]

I guess this shows that even highly skilled test pilots can make mistakes especially when they don't follow the plan...

Ahh.. "the plan"... I think that is the rub. A "fast taxi test" requires not only a plan, but execution. It's full throttle (to check stuff, like the governor, oil pressure, etc), and then at 40 knots on the airspeed indicator, (mere seconds before liftoff) you close the throttle and roll out. Considering there are only a few seconds of data gathering going on (the rest of the time is just rolling down the runway), I think this is a pretty busy time for any pilot. Throw a tailwheel in the mix, perhaps a millisecond longer before the throttle chop, and an errant gust of wind or two, and you have a whole lot of "plan" that must fit together perfectly for a reasonable outcome. This is pretty high workload if you ask me. Not impossible; certainly not cheating death - but a lot harder to pull off than a typical first flight of a properly constructed RV (IMHO).

Anyway, this debate reminds me of the old joke about "safe" flying:

"...Just make sure you always stay low and slow so you don't crash..."

 

[aerhed]

WOW this is a good one!

Seems we kinda got two "risk camps" here sorta. Sounds like everyone has prioritized their risk factors and has come down (mostly) on one of two sides. Camp1 thinks pilot suckage is the penultimate risk and Camp2 attributes less weight to that than they do to mechanical/design concerns. Very interesting Wilbur. Yes I think so, Orville.

 

[RV8R999]

The method is all backwards in most fast taxi tests. The engine doesn't need to be checked during the taxi, this is what a run-up accomplishes.

To conduct a faster than normal (words chosen intentionally) taxi test, the pilot should first determine the max speed desired during the test and ensure a good margin below T/O. I use 20MPH less in calm wind, 25-30 in gusty.

Advance the throttle about 15% and let it alone. Allow the plane to accelerate noting control inputs required to track straight, FOV, control authority, track tendancy, etc. If the plane is below the target speed, advance the throttle another 10% and allow speed to stabilize, again noting the same parameters. Do this until the target air (or ground speed) is achieved or until an abnormal tendency begins to develop. In formal flight test, this is called build-up and allows the pilot time to observe (which is what test pilots are supposed to do) and note any troubling discrepancies early enough to discontinue the test. Longer the runway the more time to observe. Repeat this test a couple of times to ensure repeatability of the parameters noted or to more closely focus on those with unexpected characteristics. If you like you can then build-up incrementally closer toward the T/O speed with each successive run. This is why flight test is so expensive and takes so long to complete correctly. To get just a little information safely requires hundreds of test runs each building up toward some limit..

There is nothing inherently dangerous in conducting a fast taxi provided the pilot understands the parameters and executes the maneuver in a build-up fashion. I'm absolutely going to conduct fast taxi testing on my T/W RV8. My limit is 30 mph (ground speed - since A/S is very inaccurate this slow) and cross-wind component less than 5kts. Primary purpose is to develop a feel for directional control response at a moderate speed prior to having to do it for the first time at full power during a t/o or after the first landing. LOTS OF VALUE here and risk is minimal if done as I've described. Also, smart to choose a "knock-it-off" point with enough space to slow down.

 

[Toobuilder]

...Primary purpose is to develop a feel for directional control response at a moderate speed ...

C'mon...

Aside from the fact that you are practicing for a condition that you will never actually experience in the real world (min power, 30 mph, on the runway), I could almost buy into this IF (note "big if") there were no other RV-8's available to fly prior to your flight. However, there is a 99.99 percent chance that your RV-8 is going to fly exactly like the one in my hangar, or any other for that matter. If there are discernable differences, they are down in the noise level. Go fly with someone!

Prior to my first flight in this particular RV-8, I had never even sat in one. I simply got a quick briefing from the prior owner, grabbed the keys, and flew the thing. It took about 100 feet of runway on the first takeoff to realize what I already knew: the airplane was a baby carriage.

Now, I'm not at all advocating jumping into a new airplane cold if you aren't completely sure, and I'm certainly not suggesting I am a gifted pilot, but it's a RV for crying out loud - not the Space Shuttle!

Heck, even the completely plans built Starduster Too is considered by most to be a "standard" (as in "known quantity") aircraft - so the way Van cranks out kits, you guys have very little surprises in store for your first flight.

I promise to quit posting if you guys come up with a legitimate reason for high speed taxi (meaning: can't get required test data any other way...)

 

[McFly]

Wow, my high speed taxi experience gave me all sorts of valuable info in how the plane felt, inputs needed and gave me the confidence I needed for a successful transition from very, very slow aircraft.

You can learn more about the aircraft going in/out of the transition speeds in a controlled manner than you can during your first landings and you rack up time/experience within the tranition speeds as well. You are going to have to get proficient in the transitions speeds one way or another. The high speed taxi allows you to get more transition experience and in a more controlled fligh regiem than from TO's and landing.

Like all aspects of flight testing, you must be methodical, you must plan, you must plan contingencies, you must know your skill level, ect. This method is not for everybody it has merrit for some.


Since everyone else has their list, here?s mine:

-Only on a big smooth runway
-Only with wind calm or just above
-I'm talking tail draggers. I would skip this test with nose wheel aircraft (more to discover and less chance of leaving Mother earth in a TW)
-ALL THROTTLE MOVEMENTS MUST BE SLOW AND SMOOTH INCLUDING POWER REDUCTION. Chop the power and you are going for a ride. I think this bites a lot of pilots.
-Don't use full throttle, not even close in an RV.

This is just my opinion formed from my very positive experience.

Good luck

 

[L.Adamson]

I promise to quit posting if you guys come up with a legitimate reason for high speed taxi (meaning: can't get required test data any other way...)

At the same time, I'm looking at some of the "flimsy" excuses as to why we shouldn't. I may have to post just as long as a rebuttle. As I said, I was interested in tracking and indicated airspeed. With my 6A, it's perfectly legitimate that the tracking could be off. It's a varible that we had to set, and wasn't all pre-drilled.

As far as I was concerned, I might have even made more than one high speed test. The plane was fully fueled, totally put together, and I was ready for flight. That's what counts, and is extremely important. For someone to sit here and tell me that I must fly on the first run of any significant speed............is nonsense as far as I'm concerned. It's no different than someone telling me I'm a fool for performing my first test flight. But that's exactly what happened a few months ago on this forum. There were two divided camps in regards to who should do the first test flight, and everyone was sticking to their personal thoughts on the subject.

Around here, most everyone has done their own test flight, and most have done at least one high speed taxi test. I have no problem with that.

L.Adamson --- RV6A

 

[jetjok]

At the same time, I'm looking at some of the "flimsy" excuses as to why we shouldn't. I may have to post just as long as a rebuttle. As I said, I was interested in tracking and indicated airspeed. With my 6A, it's perfectly legitimate that the tracking could be off. It's a varible that we had to set, and wasn't all pre-drilled.

As far as I was concerned, I might have even made more than one high speed test. The plane was fully fueled, totally put together, and I was ready for flight. That's what counts, and is extremely important. For someone to sit here and tell me that I must fly on the first run of any significant speed............is nonsense as far as I'm concerned. It's no different than someone telling me I'm a fool for performing my first test flight. But that's exactly what happened a few months ago on this forum. There were two divided camps in regards to who should do the first test flight, and everyone was sticking to their personal thoughts on the subject.

Around here, most everyone has done their own test flight, and most have done at least one high speed taxi test. I have no problem with that.

L.Adamson --- RV6A

Gear track and ASI can be verified by slow taxi, and in the hangar respectively and do not require a high speed run.
Sorry, but if you were hurtling down a runway, not intending to fly, you were not "ready for flight"! I would be willing to bet that there was no "Plan B' on your test card labeled "inadvertent flight tasks"
Anyway, like I said in a previous posting, you built it, you own it, do what you want.

 

[Andy_RR]

Here's one that might have ended in tears...

http://www.youtube.com/watch?v=F369UqjlJ2w

 

[f1rocket]

At the same time, I'm looking at some of the "flimsy" excuses as to why we shouldn't. I may have to post just as long as a rebuttle.

L.Adamson --- RV6A

I don't think anyone from one camp is going to change the opinion of the other and that's okay. It's been a good discussion.

My logic is very simple and agrees with Mark. There is an increase in risk to perform a high speed taxi test. When compared to the value of the data derived from that additional risk, I choose to skip it. I still can't seem to find one, valid reason to accept that additional risk with everything that's been written and I am trying hard to see the argument from the other side. Everything that has been cited so far can be determined in another, more safe manner.

Here's what happened to me when I tried doing one. When I first built my RV-6, the accepted gear configuration at the time was that you wanted some toe-in on the wheels/tires. As it turned out, my crude technique for setting the toe resulted in more toe than it needed. When I went out to do some fast taxiing, I experienced the gear leg shudder that Larry spoke of. Turns out that if you stay at a speed where the shudder is the worst, the airplane was very jumpy and difficult to track, and I almost ground looped it. Under normal conditions, you pass through the speed range very quickly when taking off or landing, so you only feel the shudder for a brief few seconds as the airplane settles down onto the gear. In either case, I knew the gear leg was shuffling and I suspected, and later corrected, the toe problem. I didn't need the fast taxi to tell me that, but doing the fast taxi almost caused me to ground loop.

As functioning adults, and particularly as pilots, we weight and assess the risk/reward balance every day. This is just another one of those equations. For newer, less experienced pilots, look at the pros and cons and make an informed decision based upon an honest assessment of your skills, knowledge, and experience. Then go out and have fun.

 

[Toobuilder]

At the same time, I'm looking at some of the "flimsy" excuses as to why we shouldn't.

You mean, aside from the accident statistics and the fact that it is ?generally accepted? as a poor idea?

I may have to post just as long as a rebuttle. As I said, I was interested in tracking and indicated airspeed. With my 6A, it's perfectly legitimate that the tracking could be off. It's a varible that we had to set, and wasn't all pre-drilled.

See, now you?re leaving the door wide open for me? First off, landing gear tracking can and should be established with a tape measure, and if it is so far off that it causes a dangerous situation, finding that out during a dynamic test is TOO LATE! Not to sound harsh, but if you are out of track or have a shimmy on an RV, the airplane was built wrong. Second, the ASI can be tested, verified and calibrated without ever leaving the hangar, using a water manometer: http://www.rst-engr.com/rst/articles/KP89JUL.pdf

?For someone to sit here and tell me that I must fly on the first run of any significant speed............is nonsense as far as I'm concerned. It's no different than someone telling me I'm a fool for performing my first test flight?

I hope it?s not coming across that I?m telling anyone what they MUST do? Heck, I don?t even think high speed taxi is particularly dangerous when compared to other things we do? But, IMHO high speed taxi is almost completely devoid of merit as a means of accumulating meaningful test data, and therefore, not worth the demonstrated, measurable risk.
If nothing else, this debate is forcing people to try justifying their position for fast taxi ? unsuccessfully, so far, BTW. Is this not a healthy thing?

But that's exactly what happened a few months ago on this forum. There were two divided camps in regards to who should do the first test flight, and everyone was sticking to their personal thoughts on the subject.
Around here, most everyone has done their own test flight, and most have done at least one high speed taxi test. I have no problem with that.

I have no ?problem? with that either ? As long as people are ready for flight, and they are justifying the test using sound reasoning

 

[Toobuilder]

Wow, my high speed taxi experience gave me all sorts of valuable info in how the plane felt, inputs needed and gave me the confidence I needed for a successful transition from very, very slow aircraft...

The situation you are describing my friend, is ?training? not ?test?. Test is used to explore or verify the performance of the aircraft; not to get the pilot "up to speed" with the aircraft. Self taught transition training is a whole different debate...

...and I happen to have some opinions on that subject as well.

 

[RV8R999]

How incredibly myopic the idea of Test and Training being mutually exclusive. I'll be blunt - you are simply wrong.

 

[Rick6a]

Van the Man

Hmm...what do you suppose Van really thinks of all this? Oh yeah.....
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[Toobuilder]

How incredibly myopic the idea of Test and Training being mutually exclusive. I'll be blunt - you are simply wrong.

...Depends on the context, don't you think?
I'm a systems engineer by profession, with lots of flight test and aircraft maintenance experience. Perhaps this experience has led me to more definitive view of ?flight test? than this forum is used to. Please keep that in mind.

BTW, "You are wrong" is a very a strong statement that requires some support for the reader. Let?s hear it.