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Kent Ashton

hangar electricity and other rants

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Some thoughts on that Commuter Craft Innovator that crashed:  I am getting way outside my knowledge base but here goes:

They had a prototype #1 that flew (pic below) however they apparently wanted more horsepower and stretched prototype #2  by three feet (pic above).  I imagine that was for weight and balance.  Then they widened the nose A LOT but it appears they made the front canards smaller.  They also moved the horizontal stabilizer out of the clean air above the aircraft and down behind the prop.

Now, I'm thinking that a wide nose at a positive AOA is a pretty good additional lifting surface and the horizontal stab (H.S.) in the prop blast is pretty effective at controlling pitch but what happens if you would get a little negative AOA on that nose?  Does it become a negative lifting surface?  As the AOA changes relative to the nose,  is the wide nose going to amplify the pitch change?  Are the canards powerful enough to counteract a negative pitching moment?  Also, If you had the controls positioned for a steady climb and pulled back the power, would the H.S. lose effectiveness and result in an out-of-trim pitch change?  The H.S. in P.#2 must have been highly affected by prop blast.

It is said, I think, that surface area ahead of the aircraft center of pressure is destabilzing.  They added a whole lot of that in the pitching axis while subtracting area from the front canards that would control pitch.

Then there is the Center of Gravity.  It has to be somewhere in front of the axles to make the aircraft sit firmly on three wheels.  I could not find any good side views of P.#2 that would let us judge the relationship of the CG, wing Center of Lift but the pic above seems to suggest the CG might be at about the fuselage station where the strake leading edge is.  Perhaps the aircraft depended on lift from the nose and an effective H.S. to maintain balance.  If either of those goes away, it might pitch over.  

They flew 1/3rd scale models of their first prototype.  I could find no reference to model-testing of the 2nd prototype.  Perhaps P.#1 flew well enough that they didn't see the need to model P.#2.    Interesting to think about, eh?

 

commuter-craft-innovator-alpha.jpg


-Kent
Cozy IV N13AM-750 hrs, Long-EZ-85 hrs and sold

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Ouch, sad ending. Do we call this aircraft design a canard? Maybe I missed it, but is the elevator in front (canard) or at the tail?

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Thanks, that picture seems to clear it up. Clearly appears to be elevators on the canard. I don't claim any aeronautical engineering capability, but balancing the canard and tail through all attitudes seems daunting to me.

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One time a buddy and I were rafting down the Rio Grande near Del Rio and we came to a weir.  It looked fairly benign--just a foot or two of smooth water moving over a low dam.  We hauled out and debated whether we could raft across it.  Decided not to try it.  Best decision I (we) ever made.  🙂  In the past few days I've seen several videos of weirs or weir-like situations killing people, like the poor guy in this video.     In the other videos, moped-riders trying to cross a flooded road got swept in the rotor.

How do you learn this stuff?   Youtube, in spite of all the crap, has done us a great service by showing many ways to die.

https://www.liveleak.com/view?t=RyOK_1554971362


-Kent
Cozy IV N13AM-750 hrs, Long-EZ-85 hrs and sold

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Coincidentally I've recently been watching some aviation YouTube videos from the 'Air Safety Institute' channel:  https://www.youtube.com/user/AirSafetyInstitute


Jon Matcho :busy:
Canard Zone Developer & Builder
Rebuilding Quickie Tri-Q200 N479E
Building Cozy Mark IV+ (widened rear)

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