Tail Shake

[rv7boy]

Originally Posted by tadsargent

I am curious to know what is the difference between a Stall and a Deep Stall. I have never heard this reference before today.
Thanks

Maybe this will help.

http://www.skybrary.aero/index.php/Deep_Stall

[bill@fusion4.net]

While doing my transition training in January, he had me look back when he was performing a stall. HS bounces quite a bit (Several inches). He said that he had talked to Van's about it and it was normal/expected.

Definitely makes me ready to do close checking on the HS spars and elevator attach areas during annual inspection.

Have not done any stall testing yet on mine.... Second flight completed yesterday, but I will mount my GoPro backwards during that testing.

[Stu McCurdy]

When I started flying my RV-8 I noted that it had a tail shake at the stall. I looked back and the tips of the horizontal stab were vibrating up and down perhaps 3/4". They shake because of the placement of the gear legs just below the leading edge of the wings. At the stall with the high angle of attack, the air coming around the gear legs and up and over the leading edge creates dirty air going back over the horizontal stab, causing them to shake. I stopped the shake by putting on strakes on the fuselage just above and in front of the leading edge which re-energizes the air. I now have no tail shake, no pre-stall buffet, and it lowered my stall speed.

[Neal@F14]

Originally Posted by crabandy

Checkout the flutter video and watch how much the tail wiggles!
http://www.youtube.com/watch?v=qfkkiDsEXUA

A little off-topic, but does everyone know who was piloting that twin Comanche?

It was Fred Haise!

I don't know if it's true or not but it's rumored that Fred once said that the Comanche flutter test was more scary to him than the entire Apollo 13 mission.

[TroyBranch]

I will get a camera looking back there as well. With flaps up and stick full aft, the Ten comes down like a very stable leaf, the 9 handled the same just never fell as fast. A slight check forward and it starts flying right away. There is a slight buffet the whole time but I never looked back. I was told it moved a fair bit but never considered it an issue. I would bet both it and the wings are moving a fair bit on those really turbulant mountain flights, you are just moving around to much to realize.

[flightlogic]

From reading that link, it appears I have used the term deep stall incorrectly since we don't have T tails. Maybe, fully developed stalled wing condition would have been better. Anyway, I am thinking this thread will generate some creative camera mounting now. We should see a body of "evidence" coming forward on tail shaking in all the RV types. I look forward to that.

[tadsargent]

Maybe this will help.

http://www.skybrary.aero/index.php/Deep_Stall

Ok, I read the article and this seem to be a rare event expecially with our designs, or am I missing the point.

[Lynnb]

My wife and I flew with Alex a few weeks ago and he showed us the same thing. It is a bit disturbing to see, but he did say it was "normal".

Originally Posted by bill@fusion4.net

While doing my transition training in January, he had me look back when he was performing a stall. HS bounces quite a bit (Several inches). He said that he had talked to Van's about it and it was normal/expected.

Definitely makes me ready to do close checking on the HS spars and elevator attach areas during annual inspection.

Have not done any stall testing yet on mine.... Second flight completed yesterday, but I will mount my GoPro backwards during that testing.

[Steve Barnes]

An old trucker once told me when he was hauling tripples. Never look in the mirrors, because if you do you will pull over to the side and never pull them again. The three trailers are constantly moving back and forth in and out of alignment and looks scary in the mirrors. Tripples are three simi trailers pulled behind one tractor (legal in some States on interstates).

Steve

[rocketman1988]

You may find some interesting reading on deep stalls in the Velocity aircraft...

One guy road one all the way to the ground...and survived!