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Discussion in 'The light stuff area' started by texas-buzzard, Nov 17, 2011.
Here was Mark's new design:
He really pushed the envelope.
You called it a "Trike" and I pictured a weightshift trike like what is available on the market today, but this is entirely something different. I have flown plenty of weightshift planes (including NorthWing) and also some trikes, but I don't like the the trikes at all for controllability reasons. Marks design is different though, and I do like it. I wonder if the accident has anything to do with the flexibility of the airfoil?
There were many witnesses at the airpark that probably have a better insight to what happened. i am sure it was caught on video.
I'm sorry, but I'm glad I wasn't there to witness that. I've seen several air crashes up close (some fatal) and they are always disturbing.
That plane reminds of the plane that first crossed continental USA in 49 days.
At first I thought the picture was a photoshopped joke until I scrolled down and saw the report of his crash... use of a wing not built by him is not his normal approach. I know Mark liked to wait to publicly describe his new designs... do you know what his thoughts and goals were with this one?
When you were born, you cried and the world rejoiced...
Live your life so that when you die, the world cries and you rejoice.
-- Cherokee saying
You know Dana i asked him the same question two week ago and all he said is that the design of the trike wing mounted to a U/L fush. would be a interesting challange for him.
This is only my guess about it just looking at the photo , But here goes .
And in writing this , I wonder How Mark would feel about his last flight being shown here if vid surfaced ? Can't say I would want to see it .
Deltas , Pilot weight way up front , Stall out , instant Nose down , Into a endless flip or with no leverage on the control bar to push out ... nose in . Elevators did not have enough athority or air speed to bring the nose up like a Push out on the bar with everything you got ... could have . Danm it !
Weightshift wings have reflex at the tips; that's how they are stable. Add a tail in the downwash of the center section (which I believe doesn't have reflex) and the nose up tendency may have been too much. Perhaps combined with a too far aft CG?
Still, it would seem that this could have been discovered during a crow hop... is it known whether he did any before committing to full flight? Of course a plane can behave differently while in ground effect.
As a pilot, only two bad things can happen to you and one of them will.
a. One day you will walk out to the aircraft knowing that it is your last flight.
b. One day you will walk out to the aircraft not knowing that it is your last flight.
what i read from a report is that he did several taxi tests and then lifted off, maintained a low altitude then started to climb out when the wing stalled at about 50 ft. agl. he had a BRS but was too low to be effective.
Newspaper article said the wind was 17kt at the time.
Hard to believe.... that Mark would do a first flight in that wind.
Perhaps it launched into the air unintentionally with an aft CG. That has happened to me.
We can speculate all we want but only one person will ever kniow what really happend.......
i met mark briefly at sun and fun and have a sense that he'd want others to learn and benefit from his experience.
Very true. He was that sort of guy.
For what it's worth, to me there looks to be insufficient AoA or incidence twix wing and fuselage. On levelling out, wing loses shape and stops flying. Rather like a gyro when suddenly pushed nose down. No chance of recovery.
I always enjoyed reading news about Mark newest ultralights and his experiences:
I too always looked forward to reading about Marks U/L developments, RIP Mark.
I tried yesterday my first model whith an airfoil like one in the picture in the stab. About 8' span. It surprised me it pitched up much more than expected as if the CoG was really aft. I had not enough pitch authority to override it.
There was the only flight pict of his flight at the memorial service and it was taken very shortly after liftoff. after close examination it clearly shows a full down stabilator while the A/C was climbing. after his taxi tests the previous day he said that the nose would not lift so later he raised the wing incidence +5".
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