Re: Runway excursion - canard bent


Sam Hoskins
 

Sorry to hear about this Calvin. those off runway excursions are a real bitch. I know, I've had three of them.

I am very curious why " During testing my tail was very light and I could hear the tailwheel shimmying or skidding around at the higher speeds.  At this point there was no rudder authority when using full aft elevator."

This doesn't make any sense to me.  In a stock Q-2 there is plenty of rudder and steering authority, especially at higher speeds. On your web site, http://users.xplornet.com/~vision/44/Q2fuselage.html  I see you have dual controls with the left cable going to the pilot's left foot and the right cable going to the opposite side.  IMHO this was most likely the source of your problem.

I have seen this type of installation before and have written about it..  The builder (Art Jewett) was complaining of unusual handling and had done several ground loops.  I took it for a brief taxi, then immediately shut it down  Very dangerous.  After some head scratching I realized there was full authority with the left pedal, but it was all squishy with the right.  He was losing all sorts of torque in the system because of the dual pedal setup. When you step of the left, there is an immediate response.  Step on the right pedal and the response was very slow.  If you rebuild your canard I strongly urge that you route both cables directly to the pilots pedals.

Take care,

Sam



On Tue, Apr 22, 2014 at 10:35 AM, <cbthorne14@...> wrote:
 

Runway excursion into grass and through 2 ft ditch. I am extremely happy that this occurred. What !! you may say.  I have done extensive reconstruction of this Q2, a major item was a repair to the left GU canard 3 ft from the tip and re-attatch/re-allignment of the wheel pod.  A week of low speed testing proved all was well. Then during a morning and  afternoon of high speed testing (up to 50 mph) on the inactive runway ... failure.  First excursion into a semi smooth grass area in the morning and a re-check of  the tailwheel and canard.   In the afternoon after about 6 high speed runs I exited the runway left 45 degrees and through a two ft ditch bending up the left canard. I could not get right rudder authority or steering.   The left  canard failed about three feet from the left  tip where I had done major repairs.  Not re-built strong enough it seems.  I believe a spar within the canard may have helped. 


This week the objective was primarily to get a feel for the higher speed tailwheel steering.  It turned out to be a two fold test, the repair of canard was the second and it was not strong enough for this incident. 


The future for this Q2 looks like a new Ls1 Canard with the stronger spar style wing.  Also an improved tailwheel geometry.  During testing my tail was very light and I could hear the tailwheel shimmying or skidding around at the higher speeds.  At this point there was no rudder authority when using full aft elevator.

Disappointing...I felt I was close to being finished.  Better to find these weaknesses at the home airport.


Calvin Thorne

Aircraft building web page: http://users.xplornet.com/~vision/44/tailfeathers.html

(Sent from ASUS tablet


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