Yaw in level and in overhead flight

[Peter Germann]

Shot by René Berger yesterday, the two images attached show yaw in inverted level flight and when passing overhead in the wingover manoeuvre. To see the yaw angle note the white markings at the inner tip and at the fuselage wall. Markings have been installed equidistant from the hingeline fwd. and are 20 mm (0.8in) wide. Leadout center was set at 25 mm (1 in) behind C.G.

rgds, Peter Germann

[john e. holliday]

I look at the landing gear when I am flying  to see how much yaw a plane has in level flight.   

[Dave_Trible]

Peter,  thanks for sending the photos-very instructive methodology.  Now where'd I put that colored masking tape...........

Dave

[Ted Fancher]

Hi Peter,

What a "great" idea!  I love it.  What you should do now is repeat the exercise with an airplane that has a tall/large adjustable rudder and repeat the photo sessions with it adjusted with two or three significantly different angles of offset, starting at the point where you feel the airplane is "properly" trimmed for competition and then progressively greater offsets.  Accompany the photos with an unbiased as possible description of the effects of increasing offset on the performance of the airplane (change in lap times, performance of corners, tracking, line tension, hunting, etc. come to mind).  I think many of the forum followers could learn a lot from such an exercise.  Especially those currently engaged in the thread on the pluses and minuses of rudder offset

I'd consider doing it myself except I've flown so little in recent years I'd probably get dizzy and crash in the wingovers.  Besides, I don't own an airplane with an adjustable rudder.  They're all fixed with essentially zero offset.  Even won a US Nats, by the way, with one that was eventually discovered to have been built with some "inset" on the fixed fin that was simply [foolishly] installed crooked!  It was the red, white and blue "Great Expectations" 1995 winner that, when refinished in the purple pond scum colors, had the rudder removed and a new one installed straight.  It won the Nats again with the straight rudder in 2000.  The inset was discovered when I became fed up with the difficulty of keeping it in competitive trim and laid a yardstick against the inside of it and noted that at the nose it was noticeably to the right of center-line!

Safe to say the inset didn't do it any favors but also noteworthy that it didn't completely stop it from being competitive at very high levels.

Ooops!

Say hi to Rene and "Dynomite" for Shareen and me! 

Ted Fancher

[Tim Wescott]

I look at the landing gear when I am flying  to see how much yaw a plane has in level flight.   

I look at the landing gear when I'm in level flight and contemplate the fact that, flying off of a grass field, I can never get it to stay unbent.

[Peter Germann]

Thanks for your comment, Ted. Its always a pleasure reading your highly qualified and well documented remarks.

The (electric) airplane, is my version of Igor Burger's latest Max Bee design and it has no adjustable rudder. I will however do my very best to carry this thing on but perhaps others could do so too and publish findings here.

Please allow me to add that it, most probably, was the pilot who won the 2000 Nats with a straight rudder...

Peter Germann

[Dave_Trible]

Peter,  Wanted to say I've been experimenting with your yaw stripes on two different but exactly-like airplanes.  Interesting to see they are trimmed a little differently.  This method will be in my trimming toolbox going forward.  Also am confirming ideas I've held for quite a while about side area distribution in the wind for level flight but more so vertical manuvers.  The hint here seems to be that the old 'Detroiters' aka Ares, Cobra, Ballerina and such had it pretty close to optimum. Thank You again.

Dave

[Igor Burger]

Sorry Peter, I missed this thread, but from that what I see on your pictures, I would say you have to move lines little forward. The only force which can yaw you nose out (compared to overhead) is line tension which is in level flight stronger, so I would say you have them too much back. However I recommend tou make the rudder adjustable it makes life easier :- ))) ... and if you ask, I have yaw constant (positive) in level, overhead and also with stopped motor.

[Peter Germann]

...from that what I see on your pictures, I would say you have to move lines little forward. ... I have yaw constant (positive) in level, overhead and also with stopped motor.

The leadout center is set to 25 mm (1 in) behind the c.g. (for 64 ft  0.015 lines and 5.3 sec laps) now. When bringing it more forward, such as to 21 mm (0.82 in) , line tension overhead suffered. To me constant yaw sounds like an attempt to square the circle but I will of course follow your advice and add an adjustable rudder. However, this will have to wait until the end of the flying season.

rgds and hats-off for your Liezen result!

Peter

[Igor Burger]

The leadout center is set to 25 mm (1 in) behind the c.g. (for 64 ft  0.015 lines and 5.3 sec laps) now. When bringing it more forward, such as to 21 mm (0.82 in) , line tension overhead suffered.

That is why I suggest to move rudder out :- ))))) ... but may be you can try motor offset first.

[Avaiojet]

I look at the landing gear when I'm in level flight and contemplate the fact that, flying off of a grass field, I can never get it to stay unbent.

Tim,

Gee Tim, just use a thicker gear wire.

Charles

[Mark Scarborough]

Tim,

Gee Tim, just use a thicker gear wire.

Charles

yeah cause weight sure doesnt matter right?
then the wood in the wing wont break cause the gear is stronger,,
or the vertical cg be thrown off
its a system charles,, a system, you cannot simply beef up one area without affecting another

[Avaiojet]

yeah cause weight sure doesnt matter right?
then the wood in the wing wont break cause the gear is stronger,,
or the vertical cg be thrown off
its a system charles,, a system, you cannot simply beef up one area without affecting another

Mark,

OK, well said and makes since.

 What about larger wheels? That's what we did with grass issues.

Charles

[Mark Scarborough]

its a system charles,, a system, you cannot simply beef up one area without affecting another

Charles, this is not what the thread was about,, that is a hijack,,

Tim was being his humorous self in reference to comments above about sighting the landing gear to gauge yaw in flight,,

[Avaiojet]

Charles, this is not what the thread was about,, that is a hijack,,

Tim was being his humorous self in reference to comments above about sighting the landing gear to gauge yaw in flight,,

Mark,

OK, Sorry about that.

"hijack." Like when a Thread goes off topic, as all mine do.

Charles