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Flight Testing

Bayou Bert

Well Known Member
As someone getting ready to start building an RV9A after the 1st, I have been reading throught the Van's build manual.
Van's has the flight testing in the back of the manual and reading it made the hair standup on my neck.
Does everyone push their new airplanes to the limits outlined in the manual?
Sure was a lot of parachute wearing needed.
One that really got my attentions was under Glide testing.
The manual has a statement in it about the danger of, too much or not enough rudder, and approach airspeed, causing the plane to snap over inverted! Are they talking about a stall to spin situation? They don't say spin but they say SNAP to inverted either forward or over.
Sure would like some comments on what everyone does in flight testing and about the comment on the snapping of the plane.

Bert:)
 
Hi Bert...don't fret over this stuff yet. Many airplanes, if not most, will snap over of you have a bad skidding situation when you stall, not just RV's. It's also what you do for intentional spin entry....full rudder and elevator.

Flying with a centered ball is good pilotage and what we should strive for, anyway. When you start flying your RV, you should have had transition training and you and the instructor can practise stalls with an increasing amount of rudder and explore gradually, the airplane's behaviour.

Best,
 
Thanks

Thanks Pierre, did some stalls in an RV10 last weekend getting started
on transition training with Alex De Dominics. All were ball centered but
I did hold on to one, just kept the stick back to see if if wanted to see
it if wanted to drop a wing. It stayed flat until I relaxed the stick and then
immediately flew. The buffet starts early with plenty of warning. I am told the RV9 does the same.
The manual didn't call it spin entry that's what caught my attention.
The other stuff, max G's, Vne and the other structure testing.
Does everyone push their new planes right to the limits?
Think that what's bothering me.

Bert:)
 
Every new airplane should be pushed near the limits. This is the only way to determine where the limits are.

It is STRONGLY recommended that this be done by an experienced test pilot.

No, in many cases, this is not done, but it really should be. Otherwise, how will you know the limits of the envelope?

Many people will argue that the RV line of aircraft are pretty much proven, but in reality, every airplane is different and should be treated as such.
 
What Mel said.

Having flight tested dozens of RV's and other aircraft, I can assure you that they do not all behave the same.

As noted, this early in your process, you need not fret about flight testing. There are other elephants in the room.
 
Agree with a caveat..

Some limits should not be explored without proper instrumentation and analysis such as structural limits. You cannot determine these limits without having a properly instrumented aircraft - structural instrumentation.

You can verify the designed envelop but not the limit without really putting yourself in jeopardy.
 
Testing

In in the UK with an unknown design there is a rigorous flight testing procedure before an aeroplane is signed off for build on the LAA scheme.

With known types like RV's provided they are built to plans the 5 hours of testing is required, including one two hour flight and all round the envelope.

With our Wam engined RV we were required to do a minimum of 15 hours of light testing but I actually did more than that before I got it signed off.

Every year at permit renewal after airframe inspection we do a flight test.... rate of climb, stalls, clean and dirty, vne dive, baulked approaches and the like.

Aerobatic RV's have to be signed off individually and put fully through the aeorbatic envelope.

All of this is to ensure your safety, so you know where the limits are and can fly within them. So, as others have said to not get wound up about this it is a good thing..... if you don't feel competent to do it get someone who is and during transition training explore the envelope...... but don't pus beyond it.

:eek:
 
Yeah I think I would discourage testing to see how many g's your freshly-built plane can tolerate before a wing snaps off! If however you plan to routinely pull X g's, I'd want to test that (at altitude, solo, away from populated areas, with parachute, assuming you can free yourself from the out-of-control plane if something does snap!).
 
Most RVs have a predictable stall. But, you never know. You are a test pilot. You should feel comfortable with spin recovery if you are doing the testing.
 
Flight test= test pilot?

Bert, if you're still reading this thread, a high-time commercial pilot was exploring the stall behaviour of my newly -purchased, well-built RV-9a.
I'm afraid I can't verify the exact configuration, but let's say you have to be ready for anything, and if you're not up to unusual attitude recoveries, not a bad idea to find someone who is.
He found a power-on, nose high stall resulted in some kind of tail blanking, or elevator stall that caused a sudden snap to vertical, straight ahead, nose down. Nothing like a windshield full of lake to get your attention, as you bang your headset on the canopy!
funny, that was the last time we intentionally did any stalls. Right or wrong, I don't think he would be of the opinion that Rv's have benign, mushing gentle stall behaviour....and it has given me a newfound respect for that regime.
 
I just recently started testing my -6A, so with only a handful of flights I cannot claim to be an expert. Instead, I can share my findings so far along with some (perhaps uneducated or naive) opinions.

I decided long ago to wear nomex/helment/parachute during the phase one testing. The only real downside is that I endure grief from others who didn't and think it might be overkill - but for me, it's not about the odds: it's about the stakes.

And the stakes are why I will take my plane to it's documented limits in as many ways as I can think to do so. I will be carrying my wife, my sons, friends, and family in this plane in phase two - shouldn't I, as the manufacturer, have some reasonable assurance based on collected data about how the aircraft behaves? Shouldn't I know not only how the aircraft flies but how it falls (stalls)? Shouldn't I know not only how well the autopilot works but also how it fails (altitude hold with idle throttle, for example)? The key here is, I think, to work up to the limits and not just start there. "Go from the unknown to the known, slowly" is the idea.

I know a lot of folks just "fly off" the 40 hours. And that's fine - there's nothing wrong with that. For myself, however, I want to know what will happen if we stray off the happy path, and that means exploring the corners of the envelope to verify each system (airframe, engine/prop, instrumentation, avionics) doesn't contain any big surprises.
 
Yeah I think I would discourage testing to see how many g's your freshly-built plane can tolerate before a wing snaps off! If however you plan to routinely pull X g's, I'd want to test that (at altitude, solo, away from populated areas, with parachute, assuming you can free yourself from the out-of-control plane if something does snap!).

If your aircraft is rated at 6Gs at 1375lbs (or whatever), I'd hope it gets tested to that if you're doing aerobatics with the appropriate measurements taken before/after to determine any changes caused by the stresses.

My reasoning for this is that if you only plan to pull 3.5Gs, what happens when you do but accidentally exceed that due to speed, wind gust, a sneeze, or whatever? You'll likely be a test pilot at some point - better to do it when prepped and ready for a failure than not, no?
 
I know a lot of folks just "fly off" the 40 hours. And that's fine - there's nothing wrong with that.

I'm afraid I'm going to have to disagree! There is something VERY WRONG with that.
When that happens, for the life of that aircraft, every flight becomes a test flight with totally unknown parameters.
Do you want to take you family and friends on a test flight every time they enter the cockpit?
 
I'm afraid I'm going to have to disagree! There is something VERY WRONG with that.
When that happens, for the life of that aircraft, every flight becomes a test flight with totally unknown parameters.
Do you want to take you family and friends on a test flight every time they enter the cockpit?

I was trying to be diplomatic and not offend anyone. My bad.

Myself, no, I don't want to take friends/family along on test flights which is why I'm doing the whole test card/envelope expansion/flight test program. Thus far, it each hour-long test flight has taken at least 90 minutes to plan/write down and walk through several times. Ugh.
 
I just finished my transition training with Jan Bussell at OBE, what a great guy to do your first RV flying with.
He takes you through the whole envelope of what to expect in stalls power on/off stalls, landings, even turn back after take off. (which seem very achievable in the RV.
The only wing drop I experienced was doing a climbing power/on turning stall when going to the left and air speed around 80mph the left wing dropped, just ad right rudder, release your grip on the dtick and the RV just snapped back to level flight (very comfortable) in the opposite direction, at the stall just release the stick to centre and with the P-factor the RV snapped back to level flight on it's own.

Remembering I now have a whopping 2.8hrs in RV flying but after flying with Jan I feel ready for the basics in flying our own RV6A.

Great job Jan!!!
 
Thus far, it each hour-long test flight has taken at least 90 minutes to plan/write down and walk through several times. Ugh.

I've read both AC NO: 90-89A and the Flight Test portion of the plans several times, and I'm still developing my plan. I estimate when I'm done, the ratio will be three hours planning, updating, and documenting for every hour flying.

In a previous life it was 8 hours of maintenance for every hour of ops; 3-1 feels like I'm cheating!:D
 
One thing I found nice was the new EFIS recording everything! I was able to focus on test profiles and not have to write much down during the flight.

After the flight, downloading data and plotting the data added several hours, but I do think having this capability enhances the flight portion so you can accomplish more during the flight.

It also is a way to prove what you thought you saw or did right or wrong :D

It probably put my ratio up to 10:1 :eek:
 
One thing I found nice was the new EFIS recording everything! I was able to focus on test profiles and not have to write much down during the flight.

After the flight, downloading data and plotting the data added several hours, but I do think having this capability enhances the flight portion so you can accomplish more during the flight.

It also is a way to prove what you thought you saw or did right or wrong :D

It probably put my ratio up to 10:1 :eek:

Totally agree - I didn't figure this time in before but making charts and looking at aircraft and engine performance data is fascinating. Data porn, some might call it. I'm paying particularly close attention to the engine data (CHT & oil temp) to see when the engine is actually "broken in".
 
One concept to keep in mind is "...approach to..." - insert whatever you want after the term - stalls, g-loading, slow flight, etc. I knew the published -8A stall numbers, so on first flight did slow flight nowhere near stall. On subsequent flights I gradually lowered the clean and dirty slow flight test points, until I determined clean stall was 53 KIAS and dirty 49 KIAS. Became very comfortable flying just above 55 KIAS then went into a comprehensive stall test program - straight, turning, accelerated.

First determined that no matter what the attitude, my -8A is so honest that the default recovery technique is to let go (wind my watch). Eventually got into spins.

Same with g-loading and acro. 1/2 incremental g windup turns to 6 g's. (no need to go near to 6 g's regularly - I can do 2 1/2 g loops all day). Aileron rolls, wingovers, barrel rolls before getting into overhead maneuvers.

The point is to thoroughly learn the feel of the airplane in various flight regimes so as not to be warned - not surprised - especially in the pattern.
 
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