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RV-7A flutter test - factory documentation

W

witek

Well Known Member
Hello Everybody,

I'm in the final stage of registration of my RV7A project in Poland. I was asked by local Aviation Authority to deliver a documentation (or rather confirmation) of a factory flutter test for RV7A.
I found many web pages including information that such test was done by Vans but cannot find this document.

Could you help? Where can I find this document?

Thank you
Witold
 
witek said:
Hello Everybody,

I'm in the final stage of registration of my RV7A project in Poland. I was asked by local Aviation Authority to deliver a documentation (or rather confirmation) of a factory flutter test for RV7A.
I found many web pages including information that such test was done by Vans but cannot find this document.

Could you help? Where can I find this document?

Thank you
Witold
Click to expand...

I don't believe that Vans has released any of their test results in a public document. I would give Vans a call (or email) and explain your situation and specifically detail what you need to provide your Aviation Authority.
 
You need to ask the Polish Aviation Authority what they mean by a "factory flutter test". Are they looking for flight test data showing no flutter tendencies at or below Vne or are they expecting results from an actual wind tunnel test with a special flexible, calibrated model used in commercial/military aviation industry to verify predicted flutter margins? My guess is Van has the first but not the second.
 
Last edited:
RV7A flutter test - factory documentation

There are 2 options for the flutter test for experimental aircrafts according to Polish Aviation Rules:

1. the test has to be done by test pilot during test phase - I would like to avoid this option,

2. the test is done by factory. Very often situation in case of aircrafts build from kit. Previously I build Jabiru and I got such certificate from Jabiru AU.

So I need a certificate or just a confirmation that Vans did such test when they constructed / designed RV7A.

For example here you can find such information:
http://www.tsb.gc.ca/eng/rapports-reports/aviation/2010/a10o0018/a10o0018.asp

"The kit manufacturer had conducted flight testing of the RV-7A prototype. No indications of flutter were encountered at a speed of 217 knots. Additional theoretical flutter analysis was done where the flutter speed was calculated to be 300 knots for the baseline design."

Similar statement from Vans would more than enough for me to skip option 1.

Thank you,
Witold
 
Just a thought...

Since RV's aren't certified, every one *can* be slightly different. Paint, building variations (even with prepunched kits), controls friction/play, etc all matter with flutter issues. While the other options may get you your paperwork done, only option one lets you know for sure that everything is ok. Not doing it means that each time you go slightly faster than your previous best, you're in flight test mode again. And it might be with a passenger.

Charlie
 
rv7charlie said:
Just a thought...

Since RV's aren't certified, every one *can* be slightly different. Paint, building variations (even with prepunched kits), controls friction/play, etc all matter with flutter issues. While the other options may get you your paperwork done, only option one lets you know for sure that everything is ok. Not doing it means that each time you go slightly faster than your previous best, you're in flight test mode again. And it might be with a passenger.

Charlie
Click to expand...

Reality testing is a good thing, but doesn't excitation vary? So, from reading (but not understanding yet) an aircraft could be flown into a flutter speed, but if surfaces are not excited, one won't know if an undamped instability is present? Also saying that thumping the controls may not provide an adequate frequency for excitation. Also, without proper excitation, it presents the dangers of getting into an undamped speed that suddenly goes to pieces, whereas properly excited (from a ground vibration test) the pilot can gather data with some warning.

If one is concerned about the specific variability from a test (lets assume that test is very complete, but without build variables fully explored) then wouldn't a single test of a single article have just as much statistical invalidity due to lack of a fully instrumented plane and an unquantified excitation condition?

Not preaching, just trying to understand this. I have been reading too much.
 
RV7A flutter test - factory documentation

Dear Bob,

May I ask you to call or email to Vans if you have a good contact with them?

Thank you in advance,
Witold


rleffler said:
I don't believe that Vans has released any of their test results in a public document. I would give Vans a call (or email) and explain your situation and specifically detail what you need to provide your Aviation Authority.
Click to expand...
 
Hi Mirek,

Thank you. I will contact Vans directly and discuss this issue.

Pozdrawiam
Witek

By the way - mam w Polsce kolegę o imieniu Mirek, kt?ry jest właścicielem RV7A w okolicach Radomska.


rotoiti said:
You can call them yourself, they're very friendly.

See http://www.vansaircraft.com/public/builder-support.htm for a phone number and email.

And don't worry about the accent, they could understand my Polish accent without an issue :)

Pozdrowienia
Mirek
Click to expand...
 
EU

Mirek

Poland is in the EU, RV's are accepted in virtually every country in the EU some on the basis of proven satisfactory service as in the UK, or where they have been stress loaded (Germany).

There are 343 flying in the UK, over 9000 worldwide.

I would be my bottom dollar that these aircraft are accepted into Poland when flying from abroad.

I am making this point because you may not get the information you are asking for so may have to take a different approach with your CAA.

You can add to this the fact that a number of Rockets and some RV4s exceed VNE set by vans regularly with no flutter problems.
 
Hi Steve,

I'm fully with you BUT unfortunately typical approach of CAA in Europe (including Poland) is as follows. CAA recognizes each plane as another new prototype because each can be build differently (small changes and differences). The product is not certified and it means for them the aircraft was built without adequate supervision and there are many areas which were not verified in a proper way ? diffretly like in case of certified aircraft.
I bought RV7A kit but I can name it "WITEK" if I want because CAA doesn?t recognize it as a RV product but only as a new Experimental aircraft.

All the best,
Witek

WAM120RV said:
Mirek

Poland is in the EU, RV's are accepted in virtually every country in the EU some on the basis of proven satisfactory service as in the UK, or where they have been stress loaded (Germany).

There are 343 flying in the UK, over 9000 worldwide.

I would be my bottom dollar that these aircraft are accepted into Poland when flying from abroad.

I am making this point because you may not get the information you are asking for so may have to take a different approach with your CAA.

You can add to this the fact that a number of Rockets and some RV4s exceed VNE set by vans regularly with no flutter problems.
Click to expand...
 
witek said:
Hi Steve,

I'm fully with you BUT unfortunately typical approach of CAA in Europe (including Poland) is as follows. CAA recognizes each plane as another new prototype because each can be build differently (small changes and differences). The product is not certified and it means for them the aircraft was built without adequate supervision and there are many areas which were not verified in a proper way ? diffretly like in case of certified aircraft.
Click to expand...

It seems like a flutter test report from the factory would also be of no value then, because there is nothing (in the CAA eyes) to assure that you RV-7 would be representative of the one originally tested......
 
rvbuilder2002 said:
It seems like a flutter test report from the factory would also be of no value then, because there is nothing (in the CAA eyes) to assure that you RV-7 would be representative of the one originally tested......
Click to expand...

Logic does not always work here :)

Each CAA body in Europe have there own ?particularities? ....

If the Polish CAA have asked if a ?flutter test have been done? ... no question that a statement from VAN stating that flutter testing has been done on the RV7 prototype ... along with all the normal disclaimers etc.. etc... This would be ?helpful? for our Polish friend .....

Would keep the European bureaucrats happy !
 
Witek,

A flutter test is not as demanding or dangerous as it might first seem and may be your best option. A typical test point is a control rapp at (or very close to) Vne. There is no history of flutter problems in RV-7s, so this would be a low risk test - and one that should be carried out on all new build aircraft. The technique is well known - basically ensure the aeroplane is pointing up hill so it will slow down if anything untoward happens. Get an experienced test pilot to fly the test for you if you have no experience (there are several around who would enjoy the chance to fly an RV-7). Ask your CAA what test evidence you would have to collect to satisfy their needs - or you could propose a test schedule and see what they say.

Pete
 
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