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Year long discussion of "Another nosegear failure" -09/19/2010

rocketbob

Well Known Member
Last night a good friend of mine flipped his RV-6A on our airpark. I won't go into too many details right now until I gather up some more photos of the damage but its VERY easy to see what led up to the chain of events. Gene and his passenger are OK but suffered some substantial cuts while getting out. Airplane appears to be totaled.

I will say this: this 6A went together in my hangar and I have had MANY discussions with him about the nosegear, even after the mod. The design of the rod and fork are INADEQUATE, even with the new fork mod from Van's. I will go into that in more detail later. There is ample evidence here to support this position which I will provide.

Sorry for the grainy iPhone photo but it was getting dark.

photo%20%281%29.JPGg
 
Man these pics break my heart!!!

I have a friend that built a 6A that was very fond of grass strips in his 150 but I doubt he will ever land on grass after seeing all these incidents.

He has perfect form and hardly uses his nosegear. He has mastered the art of balancing it on the mains in most all conditions. Even still, he won't fly on grass.
 
Man, I'm so frustrated with seeing reports like this so often. I don't know if I'll ever get the nerve to land mine on grass, unless Vans finally gets around to doing something to provide us with a retrofit to dramatically reduce this risk, which has been clearly demonstrated as very real by now.
The airport near my family cottage is grass, and I hate the fact that I may never get the courage to fly my -9A there. A big part of me wishes I'd built a taildragger now. I wish I'd known this before I started building.
 
Evidence

RocketBob,

The picture you show has all the markings of what is becoming the "classic A model pole vault crash."

If you really have enough evidence to prove that there is a problem with the nose gear design, and maybe the solution, I urge you to come forward with the evidence as soon as you can. It is important to see if there is a common denominator, besides maybe grass strips, behind these instances.

IF you are right and IF there is a problem, you may save someone else losing their plane.

Yesterday, five of us RV builders, with a total of four completed planes and four more in the later stages of construction(me being the newbie), stood around the new Beringer nose wheel discussing all "The Mods" that have been done to the A model nosegear, wondering if the issue was real or solved. Most of us have had or are building A models.

I can already hear the din of the naysayers, claiming "pilot error", and "keep the nose wheel off the ground," but if there is a design flaw it needs to be explored and fixed.

Dave A.
6A build
 
...IF you are right and IF there is a problem...

I think we are well past knowing that the nose gear nut will dig into the ground in certain situations, and that once that chain of events start, there is no recovery. Whether this is a "design flaw" or an operational limitation is debatable, but it is a real risk.

The nose gear on a tricycle aircraft is not part of the landing gear, but simply a taxi aid. I'm not sure if technique was at fault in this particular incident, but I have seen enough "A model" drivers abuse the nose gear to know that there are likely to be lots more flipped RV's in our future. Until there is a more forgiving design, or the entire population of "A model" drivers stops landing in such a way that the nut digs in (for whatever reason), we're going to see pictures like this. Neither solution seems easy.

In the meantime, awareness is our friend.
 
Please take pictures of the nut area of the nosegear. Is there dirt/grass?

Take pictures of where it dug in. Was there a depression/soft spot, etc there?

Was the ground soft (recent rains?)

Just stay off of grass in A models.

Please describe how they got out. That looks very tight. Did they have a canopy busting tool?

Glad they are fine. Insurance will take care of the plane.
 
A little intro to Rocket Bob

For those of you who may not know Rocket Bob, he is an excellent and experienced mechanic (amongst other skills). Although I've never met Bob in person, we've spoken and emailed many times. He's been forthright with great advice and tech tips during the construction of our second RV.

Before anyone decide to flame Bob for what he's likely TO SAY in the future about nose gear, know that his intent is to promote safety and improvements.

Given that our "RV fleet" has two nose gear airplanes and one of them already suffered a bent nose gear almost identical to his friend's airplane, I look forward to any tips and ideas he will deliver.

Bob, please extend my sincere condolences to your friend. If there is anything we can collectively do or any experiment we can contribute to, please don't hesitate to ask.
 
Barry, no one is dissing Bob. I converted to the new fork PLUS added a "skid" of carbon fiber internal to the bottom front portion of the nose gear wheel pant.

The concept, right or wrong, is that if the gear collapses or falls into a hole, maybe that skid will prevent the nut from contacting the ground and acting as a pole vault.

Perhaps Bob has an idea to prevent these problems. If so, I may adopt them or .... just stay off of grass. To my knowledge, it is only..or almost exclusively... a soft surface issue.
 
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It is fairly clear to me that the Nose Leg design on the -A models is a "vulnerability". It is less forgiving than it could be of a less than perfect pilot technique, poor surface, or just bad luck.

The "root" problem of the design is the fact that -As are traildragger conversions, with the nose leg coming back at an angle to the firewall i.e. there is not enough room / structure to put on a vertical leg. You therefore have the pole vault which "flips" them, rather than the classic C152 "nose leg breaks off".

The bolt area / bend in the leg which catches the ground, maybe assisted by a bump is where the "improvements" have been made, and presumably reduce the likeliehood of a "flip". However, they are "reducing the chance of a problem", not eliminating it. Ditto good pilot technique / training.

Is it a design flaw? Mistake? Hard to say... it is just not "ideal". Is there an easy solution? Doubt it. Is a taildragger the answer? Well, they have their hazards - all the nosewheel "characteristics" do is level the scales somewhat as to which is easier to fly / safer / less likely to become an insurance statistic.

Andy
 
More information

Hello Bob

Thanks for the picture, very sad!

What would be of interesst:

- Tire pressure?

- Matco or Grove wheel?

- Axle spacer yes or no?

This are just a few very small points that in the summ have influence into the wrong direction.

Thanks Dominik
 
The airplane is locked up in a hangar until the FAA gets here Monday morning. I will take some photos Monday night.

Synopsis:

Very experienced pilot with plenty of tailwheel time, used to own and fly a Stinson V77 Gullwing.

He used to keep his airplane in my hangar but was concerned about the nosegear not being up to the rough spots in the runway, so he moved it to a nearby airport. Yesterday he elected to not give rides to friends until the wind shifted in favor for 18 which is smoother. This was his third landing of the day here.

Had the nosewheel fork mod according to Van's service bulletin.

Landed and rolled out over a spot on the runway with a bit of a hump. Following the hump is a low spot where grass does not grow well. The airplane took a bounce over the hump and the nosewheel came down in the bare spot. It was clear to see where the front wheelpant broke and the nut started digging in. There is paint worn off the fork and mud in the nut. It slid approximately 90 feet when the nosegear leg finally yielded and flipped the airplane over. He first heard a bang and felt the nose drop, as soon as that happened he pulled all the way back on the stick and heard another bang, then flipped.

There is a groove dug into the runway 90 feet long where the fork dug in.
 
I'm too chicken to land in grass, so have nothing to add but my personal condolences on this tragedy. Glad to hear everyone walked away, and hope none of the injuries are serious and that the damage is easily repairable.
 
This is not rocket science

Flame away, but my opinion is that this is a serious design defect that needs to be corrected. If this was a certified aircraft, AD's would have been issued long ago.

There is simply too much flexure on the forward end of the gear leg/spring. Redesign, making the gear leg substantially rigid, and put the spring/energy dampener near the firewall. That way, when the gear flexes, the nut will not move closer to terra firma. Yes, there will still be issues if you wheelbarrow your landing, but I believe 90% of the problems will be solved, with practically no increase in weight, and some pretty simple engineering.

You may be the best pilot on the block, but someday. . . . you hit a hidden depression, or a runway or taxiway lip and you are on your back.

Simply unacceptable!

Roger
 
Rough strip

Bob,
Thanks for the synopsis. Looking forward seeing whatever pics you can get. Do you know if the injuries your friends sustained were from the canopy fracturing during impact or from exiting the cabin? Did they have any of the plexiglass breaking devices to use?

Ron,
I already have the new gear leg required by the 6A SB and the newer nose gear fork. My wheels are the freewheeling Clevelands with the spacer and not the Matcos so I haven't opted for the Grove wheels. The 6A already has a bit of a nose high attitude compared to the 7A and the Beringer may be too high? Do you have any pics of your carbon fiber skid or tips in doing that?

Dave A.
6A build
 
I am very sad for their accident but happy that there is no long term physical injury to them. I wish for a fast recovery from all of their injuries.

I am the second chicken on the block to want to land on grass but even on good smooth taxi/runway, I practice the safe taxing for RV (i.e. stick pulled to my stomach all the way) and will keep the nose wheel off the ground as long as there is airspeed to do so.
 
Collaboration? Count me in.

After I bent my nose gear, I "improved" the front wheel rotation via the use of a steel spacer on the front shaft so that the "seals" do not inhibit rotation. Any air conditioning supply store can sell you the spacer which you simply machine to fit. It's nuts (IMO) to have seals that inhibit rotation.

My second mistake was flying the 9A w/o the front wheel pant. Although it did not help Bob's friend, others have reported that a reinforced pant bottom served as a skid plate alike those we use on racing motorcycles.

Breakout is checked often as is tire inflation & balancing. Nothing mechanical is left to chance.

After my nose gear bent, I walked back over the pavement and found a significant runway undulation where two runways met that may have precipitated an excessive fore/aft rotation. Sounds like the bare patch Bob mentioned.

Like I said in the earlier post, I'd happily participate in an RV program that seeks to solve this nemesis. In addition to promoting safety, our insurance rates might decrease if we could prove a remedy.

Bottom line... it's been 200 hours since I bent the gear. If my landing lineup and is not perfect, it's go around. Practice, practice, and more practice is essential. The nose wheel NEVER touches the ground until gravity demands it, but all of that said, we cannot completely control the surfaces we land on. Similar to "mtnclimbers" sentiments, my 9A (and the 6A we're close to completing) will never see a grass or dirt field unless absolutely necessary which is too bad because there are lots of neat places we'd like to visit.

These airplanes are incredibly responsive and wonderful to fly especially in busy places like Socal. Solve this problem and these airplanes will be as perfect as my wife.
 
the problem with grass is that even with the best of pilot technique, there is always a range of speed upon rollout where the elevator has no effect. the pilot then essentially is a passenger until reaching a safe taxi speed, which also is quite low due to the short distance between nose and main gears, leading to porpoising effects. the uneven nature of grass will increase this bouncing risk considerably.

so for us it is clear, we will stay off grass! the remaining unmitigatable risk is just not worth it. we can live without the few grass fields.
personal choice of course.

rgds bernie
 
Grass Strips in a 6A

So after 950 hours in an unmodded 6a, I should fear grass strips forever.
I'm sure gonna miss dining at Cedar Mills (3T0). What about you Rosie??
 
The predominate thinking is that the tipping point event occurs when the nose gear nut digs into the pavement or dirt due to the nose wheel striking either a pothole or bump. In order to understand the forces I performed a bending moment analysis of the gear based on a loading spectrum. Essentially the vertical forces that can be generated through a number of events will not result in enough deformation to cause the gear to tuck under enough to contact the surface. Only fore-aft forces are critical based on the geometry of this gear configuration. The forces from rolling friction and an upset event such as impacting a pothole or small bump are also not sufficient to generate the required loads to cause a nose gear tuck under.

The discovery of the critical tipping event came from a near tuck under I experienced in my RV-8A on a very smooth asphalt runway. I had let a pilot in the back make a landing and he immediately let the nose down firmly after landing, which is what he does on his Piper 140. The result was the tire deformed enough to come in contact with the side of the speed cowl. What was interesting was that the front of the speed cowl had significant asphalt scrape marks. It was apparent that the gear had tucked under enough to scrape the front of the speed cowl but not enough to catch the nut. I came very close to a tip over event. Had the tire deformation been caused by a bump or pot hole, I would have pole vaulted.

It turns out that when the tire expands and contacts the speed pant, it instantaneously acts as a brake before it shatters. I modified my analysis to take into account the force generated from a braking action on the nose gear. The magnitude of this particular brake force is significantly greater than those caused by a pot hole event. This additional instantaneous braking force is what appears to provide the critical force required to get the nose to tuck under.

This critical event is primarily a function of tire pressure and tire-to-speed cowl separation. The solution is to increase the separation between tire and speed cowl and run the tire at a high pressure. I am now running my front tire at 50 psi.

The nose gear design is adequate for these airplanes.
 
I'd be interested in knowing whether other tricycle gear aircraft with a similar configuration (Grumman's, perhaps?) have similar problems.
 
That sucks!

My thoughts go out for the owner/pilot....that really blows! Hopefully it is fully insured and he can find a nice RV-6 replacement on barnstormer.
 
"Speed cowl"???

The solution is to increase the separation between tire and speed cowl and run the tire at a high pressure. I am now running my front tire at 50 psi.

The nose gear design is adequate for these airplanes.

..... are you referring to the "wheel pants"?
 
Here's some photos & info to assist the discussion

Doug:

Thanks for the input. Here's some additional data to consider. My 9A was already on the paved runway, engine at idle, the front wheel was already rolling, the wheel pant was not mounted to crimp the tire, but this was the result as I passed over the intersection of two runways.

bentgear.jpg


Once we fork lifted the airplane onto my trailer, two of us bent the front gear a little straighter with a pipe wrench to assist with the long ride home.

gearlegafterwebentit.jpg


I'm no engineer, but I'm not a weight lifter either. The fact that two of us could bend the gear straighter with a pipe wrench is worrisome to me. Perhaps once it was bent, un-bending was easier, but later on we had the leg tested for hardness and it passed.

wornfork.jpg


The tire was perfect and fortunately, we did not roll over.
 
I wonder if the mains are just to far behind the center of gravity?

No. If they were, I wouldn't be able to climb aboard myself, without the tail slamming the ground. Two at a time will do it. As it stands right now, rotation forces are right, with the mains where they are.

L.Adamson --- RV6A
 
My 9A was already on the paved runway, engine at idle, the front wheel was already rolling, the wheel pant was not mounted to crimp the tire, but this was the result as I passed over the intersection of two runways.
This seems consistent with Raiz's excellent model / analysis (in another thread) that predicts that a nose gear leg will be stressed to yield strength when taxiing at 10kts over a 2" rounded bump (dependent on weight / CG).

His model predicts that this happens before the nut touches the ground. Of course, immediately after the leg is stressed to yield strengh, it "yields" which is a fancy way of saying that it bends more than it can spring back from. Then the nut touches.

Point is, if Raiz's model is accurate, the nut touching is not the cause, but part of the effect.
 
Mike,
I mean wheel pant.

Mr Nomad (barry)

What was the gap between your tire and the wheel pant at the center of axel on the lower side. That is the gap that is critical. Also what was the tire pressure at the time of the incident? These are the two critical factors. Your situation is the classic case. The issue is when the tire hits an obstruction the tire deforms and then comes in contact with the wheel pant and that contact acts as a braking action that generates the load necessary to cause the tip over.

Normally when an alloy is bent, it strain hardens, and rebending the same area almost always requires a higher force.
 
Nosegear

I live on a grass strip and after 250 hours and too many landing to count, I converted my 9A to a 9. I now have 400 hours and I no longer have to worry about the nose gear. It's only a minor pain to do the conversion.

Joe Ramotowski
RV9 Formally 9A
400 hours and counting
RV8 in progress
 
Guys,

Its heart breaking to see another airplane that is the product of many hours of work on its back, but I think most of you are jumping to conclusions that are not supported by the available data. Raiz has studied our noselegs in detail (see http://www.vansairforce.com/community/showthread.php?t=61178) - and shown that the basic problem is that the leg is unable to take significant loads without folding, these isn't sufficient travel available. If the nut hits the ground the leg has probably already failed. I don't know what to do to fix it, but the basic problem is that too much load was applied to the leg - for whatever reason.

Ensuring there is minimum static load on the nosewheel and avoid anything other than light braking on a bumpy surface are two ways to minimize the liklihood of collapsing the nose gear. I will continue to land my 6A on grass airfields, but only when I know that there are no bumps/holes that might load up the nose gear near to its limit.

Pete
 
I am not commenting on this particular incident, but I feel there are two aspects that do not get enough mention.

Firstly, Vans max nose wheel weight for each model. It is easy to load up the aircraft and check gross weight and C of G but forget about the max allowable nose wheel weight. I always make sure I have enough weight in the baggage compartment so I am comfortably under Vans max nose wheel weight.

Secondly, it is all very well having the new style fork with the increased clearance but you lose some of the advantage with the low clearance on the standard nose pant. I suspect that if the lower surface of the nose pant cone hits the ground it will fracture, produce extra drag and increase the stress on the strut. To me it seems that the lower nose pant cone needs to be raised and also strengthened. I modified my nose pant over three years ago.
http://www.vansairforce.com/community/showthread.php?t=20219

Fin 9A
So far, hundreds of trouble free grass landings including a couple of less that perfect landings and heavy braking on rough surfaces.
 
Guys,

Its heart breaking to see another airplane that is the product of many hours of work on its back, but I think most of you are jumping to conclusions that are not supported by the available data. Raiz has studied our noselegs in detail (see http://www.vansairforce.com/community/showthread.php?t=61178) - and shown that the basic problem is that the leg is unable to take significant loads without folding, these isn't sufficient travel available. If the nut hits the ground the leg has probably already failed. I don't know what to do to fix it, but the basic problem is that too much load was applied to the leg - for whatever reason.

Ensuring there is minimum static load on the nosewheel and avoid anything other than light braking on a bumpy surface are two ways to minimize the liklihood of collapsing the nose gear. I will continue to land my 6A on grass airfields, but only when I know that there are no bumps/holes that might load up the nose gear near to its limit.

Pete

Raiz himself has admitted it is only a model at this point, with no practical validation. he has good data but it is really as much a theory as anything else out there. Only after physical testing validation will it be "proven"
 
Keep the weight off the nose wheel

RV-9A Pilot/Owner
Always....always...always keep the weight off the nose gear!
Whether it is during taxi or landing. I was taught ( by a great instructor out in Scappoose Oregon) to give the nose gear lots of respect. I have found that it takes very little effort (or skill) to stay off nose wheel and keep the weight on the main gear.
 
Gppd work Bob, keep us informed.

Did the pilot have the stick back on roll out? You said he pulled it back after the bang. It makes no difference, just curious as to what he says. Does he usually land with the stick in the gut like a TD?
 
Rocket Bob:

The NTSB's investigation of the RV nosewheel failures found one consistent trend -- low time in type. How much time did your friend have in RVs?

I'm not going to say that the nosehweel can't be improved or even that there isn't a "design flaw". I do believe there is room for improvement. However, look at youtube videos of RVs landing -- absolutely ZERO soft-field technique in many of the videos I just cringe while watching them.

If you put the nosewheel down on an RV-XA less than 3 seconds after the mains, YOU ARE NOT LANDING PROPERLY.

With my 7A, 180HP O-360, C/S prop I can typically hold the nose off the ground at or above 28kts. If your nosewheel is on the ground (in take-off or landing) at say, 35-40kts YOU ARE NOT FLYING THE AIRPLANE PROPERLY!
 
It's a design issue

When you look at the nose gear design the thing that stands out to me is that being made of spring steel it can move in any direction. The Sky Star design which is a solid leg pivoted off the firewall with rubber donuts for suspension allows the leg to only go up and down not backwards.

I agree that pilot error can be a factor in the failures but really lets be honest an occasional landing is not perfect and there should be a margin of safety in the design. The leg needs to be a lot stiffer with flex higher up to stop the tendency to roll under. I am also suspicious of the front tire pressure as given the narrow clearance between the wheel and the fork any momentary deformation of the tire could jam the wheel in the fork causing the leg to drag back.

I have an RV6A and operate off grass but have become very careful with landings using a nose high attitude with the stall warning blaring at touchdown and getting the stick back as far as possible as soon as possible. After reading these forums I have increased the tire pressure to well over 30 psi. I have the latest leg and fork and solid spacer on the axle.
 
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Rocket Bob:

The NTSB's investigation of the RV nosewheel failures found one consistent trend -- low time in type. How much time did your friend have in RVs?

I'm not going to say that the nosehweel can't be improved or even that there isn't a "design flaw". I do believe there is room for improvement. However, look at youtube videos of RVs landing -- absolutely ZERO soft-field technique in many of the videos I just cringe while watching them.

If you put the nosewheel down on an RV-XA less than 3 seconds after the mains, YOU ARE NOT LANDING PROPERLY.

With my 7A, 180HP O-360, C/S prop I can typically hold the nose off the ground at or above 28kts. If your nosewheel is on the ground (in take-off or landing) at say, 35-40kts YOU ARE NOT FLYING THE AIRPLANE PROPERLY!

Well, it depends completely on loading. On landing (with a config like C/S, 180hp), if the pilot is light, the tanks are full, no baggage, it will be impossible to keep the nose off at those low speeds, unless there is a strong headwind, or you've put lead in the tail. Empty tanks, baggage, then yes, it will stay up longer, a lot longer. Full up elevator is as good as it gets. During take-off, the nose will of course come up much faster, as it's breezy back there with full power.

The 8A drivers must see a fairly extreme variation in the nose up speed, depending on whether bubba is in the back or not.
 
Well, it depends completely on loading. On landing (with a config like C/S, 180hp), if the pilot is light, the tanks are full, no baggage, it will be impossible to keep the nose off at those low speeds, unless there is a strong headwind, or you've put lead in the tail. Empty tanks, baggage, then yes, it will stay up longer, a lot longer. Full up elevator is as good as it gets. During take-off, the nose will of course come up much faster, as it's breezy back there with full power..

Yes, it will vary, but not that much. I ALWAYS, WITHOUT QUESTION have it off the ground above 35kts (notice I said I typically can hold it off the ground at 28kt). Most of my flights are solo and local (hence no baggage).

Also, I see that you have a -6A which I only have about 25 hours in so maybe they are slightly different (I know they have different gear leg geometry)?
 
I am not an engineer so I can't speak to the design of the nose wheel. However, I know lot's of guys are choosing nose wheel aircraft because of the idea that some how a tail wheel is "harder" to fly. The truth is, it's just not the case. With good training and technique, the tail wheel is just as easy and at times more fun than a nose wheel. And, with the apparent nose wheel troubles, if there are those on the fence, don't worry about choosing a tail wheel version of the RV. Even the -9, is a great tail wheel option and though a challenge to land at times, it's very durable and even a "bad" landing is very easy to salvage.
 
I'd be interested in knowing whether other tricycle gear aircraft with a similar configuration (Grumman's, perhaps?) have similar problems.

I owned a FG Velocity prior to a 6A and also have time in Tigers. Very similar setups to Vans but in both cases they are stronger, less springy setups. The Velocity downtube was larger and pivoted at the top held against a high compression rubber bar. The lower assembly is nearly identical to an RV but the nut is higher. Funny part is that there is no weight on the Velocity gear leg as the engine is in the back. The lack of weight actually increases the shimmy problem though. Grummans have larger, more rigid downtubes and do not have this problem although they also have shimmy issues if the kickout force is too light.
 
I am not an engineer so I can't speak to the design of the nose wheel. However, I know lot's of guys are choosing nose wheel aircraft because of the idea that some how a tail wheel is "harder" to fly.

Not really. I just didn't like the looks of the "6" in squatting position from certain angles. The wings are just too short, which made the 6A look more substantial from a ground view. Other than that, the A models do have more frontal visibility, and are slightly easier to deal with in cross winds.

However, just like anything else, I'm ready for a change (just for something different), and a TW would be just fine. How much would a conversion cost....? :D

L.Adamson --- RV6A
 
I'll try and answer a few of the questions that have been asked.

No, he is not a low time pilot and he has 400-500 hours on the 6A he built. He is now building a -12. He has to wear a neck brace for two weeks but didn't require any stitches. I actually got some cuts from the canopy when I crawled in it to flip the mag switch off and shut off the fuel. The rollbar did its job but is crushed. The canopy shattered but not completely, so they had to kick it out to get out.

He was rolling out when it happened, so the nosewheel had been rolling I'm guessing at least 100 feet.

Frank Smidler witnessed the accident so hopefully he chimes in. He is a forensic engineer and an excellent witness to have in this sort of situation.

Everyone can speculate all day long but one thing is certain: the nosegear failed. It can happen to anyone regardless of time. The nose gear is not robust and lets talk about how to fix the problem. From here on out lets focus on fixing the problem. The revised fork from Vans does absolutely nothing to fix the problem. There is too much leverage applied by the axle on the weakest part of the nosegear leg, which is at the bend. This is what causes them to bounce as badly as they do in normal operation.

The fix is simple: Shorten the distance between the axle centerline and the centerline of the vertical pivot centerline and raise the front of the fork to where it would be impossible for it make contact with the runway. Get rid of the bend in the gearleg. How do we do this? We'd have to build a new fork that looks and operates like the tailwheel forks that have now become popular like the one Vince Frazier sells, but in reverse. What this does: gets rid of the bend in the gear leg, it allows for greater ground clearance at the front, lowers the bending moment between the centerlines, and moves the nut to the top where it can't get dragged underneath. It would make the airplane handle better on the ground since the shorened centerline distances would improve stability, just as it does with the aftermarket tailwheel assemblies.

In the last year I have done over 30 formation section landings with a good friend in his RV-8A, which has given me a unique perspective of what is going on with the nosewheel. I need to get a video of it soon and post it here because its a real eye opener how much the nosewheel bounces up and down even on a perfectly smooth runway.
 
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Probably already asked in other threads, but what is Van's official word on this? They say it's perfectly fine, and always pilot error? Can any of the Van's fellas chime in here (without getting in trouble)?

I've bought a Beringer, plan on modifying my wheel pant, and adding wood stiffeners to the gear leg, but this is starting to get ridiculous.

Forget grass, I look at some of the "back road" taxiways at 52F, and don't think I would be comfortable taxiing around on them. Then I read about intersecting hard surfaced runways, GEEZ!

Talk about a motivation killer.

Joe
 
What happened is regrettable.

My condolences go out to the 6A owner. It happened to me in 2003 with a dead engine on a field path and I feel the pain of a wrecked airplane and a few cuts crawling out of the mess.

That being said, anxiety over these incidents perhaps should be defused just a bit. There is an explanation and once a pilot is aware of it and recognizes the traps, it is preventable.

After my flip and a repair job, we moved to an air park with a turf runway. Since the move in 2005, the airplane has been landed about 416 times on this runway, all but 40 on grass. (we paved the strip this summer)

So what does that say? It says flying an -A model can be a very normal experience.

The flip events are caused IMHO by

#1 the small Lamb tire
#2 poor field conditions and not knowing it
#3 landing on the NG

The skinny Lamb tire will drop into a large crack on hard surface and is easily launched by mini ski jumps on rough turf. These circumstances must be avoided.

The NG is not designed for landing, it is for taxi and take off only just like a B767 or F-15.

My NG cover has been wrecked so many times jumping from turf to asphalt, it has some 8 to 10 plies of fiber glass inside and has become somewhat of a skid - it keeps the infamous nut inside when the skinny tire sinks in wet conditions.

I am tail wheel qualified although I don't fly one. One thing remembered is fly the airplane until it is parked. The same is true in protecting the skinny tire up front. With engine running and full aft stick, the NG may be on the ground but it is mighty light. If you land nose high with nearly full aft stick and taxi that way, it probably will never flip on you.
 
An Idea!

Hey, I have an idea! Why don't we split this thread... into Person and Machine.

Then all perfect pilots who find miraculous ways to keep their nose in the air, down to below taxi speeds, under all (100%) conditions; can go over to that thread and discuss improving the margin of safety through piloting skills.

And the rest of us can remain here and work on improving the margin of safety of the machine through careful analysis and mechanical improvements.

Might work. :eek:
 
Hey, I have an idea! Why don't we split this thread... into Person and Machine.

Then all perfect pilots who find miraculous ways to keep their nose in the air, down to below taxi speeds, under all (100%) conditions; can go over to that thread and discuss improving the margin of safety through piloting skills.

And the rest of us can remain here and work on improving the margin of safety of the machine through careful analysis and mechanical improvements.

Might work. :eek:

GrayHawk,

Careful analysis and mechanical improvements are not much of a mystery. Hang a Cessna NG strut and a 500 or 600 tire, problem over (maybe). It can be banged on all day, every day and may not flip, although I did buy a rebuilt wrecked 150 once upon time - it too had been flipped by a screwed up landing.

Incidently, that airplane N6930G is still flying - but I don't miss it one bit at all.

The RV wins hands down as it is. :)
 
My airpark has a 2600' paved runway (16/34) and a 1500' grass cross runway (25, can't land or take off to the west due to power lines). During summer afternoons there is often a fair cross wind from the west. I have yet to land on the grass strip. I'll land with a 15 knot crosss wind rather then land on the grass.... Scares the ?$&@ out of me. I always land with the stick in my gut, but these flips seem to happen to far too many pilots with more time than myself. Would wooden stiffeners wrapped with carbon fiber help? Heck you could make it large enough and shape it so the fairing was not even necessary.
Just a thought???
 
Eye witness

You may be the best pilot on the block, but someday. . . . you hit a hidden depression, or a runway or taxiway lip and you are on your back.

Roger

I had just fueled my airplane and was walking around the wing looking down the airstrip at the 6A landing. It hit a rough spot, the nose popped up and came down hard then a second later it was standing on its nose, tail straight up. It continued over on its back in a cloud of dust from the hard dry ground. My heart sank and my first thoughts, as was everyones, was the pilot and passenger alright? Thankfully they are.

I had landed my RV-6 and hit the same spot 1-1/2 hrs before. It threw my main gear up then my tail wheel up into the air and I became busy for a couple seconds. I agree with Rogers comment, you will be fine on most grass strips most of the times, but hit the wrong spot on a particular runway and no mater how good you are it may not be enough.

As an engineer the rate of failure of the nose gear is unacceptable. Some may call it abuse but it is too common not to be dealt with. I have not performed any analysis on the gear leg so I don't want to speculate on the best way to improve the design but as an experienced Engineer I believe it should be possible to improve it with minimum weight and cost. I respect Van's Aircraft as a quality company with high Engineering standards. I hope they continue to take the high road and revisit this issue.
 
GrayHawk,

Careful analysis and mechanical improvements are not much of a mystery. Hang a Cessna NG strut and a 500 or 600 tire, problem over (maybe). It can be banged on all day, every day and may not flip, although I did buy a rebuilt wrecked 150 once upon time - it too had been flipped by a screwed up landing.

Incidently, that airplane N6930G is still flying - but I don't miss it one bit at all.

The RV wins hands down as it is. :)

Not denying that at all. I agree with you. I love my RV.

But I still think the two can be separate & improve the atmosphere a little!
 
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