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James Maher wrote:
Ernest,
Beware of the sliding door.
Roy Jensen had sliding landing gear doors on his Delta that resulted
in a forced belly landing when they could not be opened.
What would happen if the door jambs shut or closes by itself?
Better to have some sort of spring loaded flap that defaults to open if the actuator fails.
Murphy dictates that it will fail.
Just playing devils advocate.
Jim
I don't know all of Roy's story (was he the one doing the belly landing at Oshkosh?), but I've considered what you're saying. The big thing I worry about with this design is the aerodynamic forces pushing on the door, making the friction to high to move it. I believe that is what happened to Roy? People tend to understimate what a little airflow can accomplish, even while it is lifting them and a heavy aircraft off the ground. I can't fully quantify all the aerodynamic force beforehand, but there are some mitigating factors on my behalf that Roy didn't have.
1) His gear doors had to withstand the brunt of the oncoming air. I'll have a radiator absorbing some of that energy.
2) The angle of incidence should be very acute, shaped by the duct that is trying to align the exit air with the external air flow.
3) I don't see a need for ever having the panel more than half closed, and it would only be closed in cruise flight. If the friction is too high to close it...no foul. Maybe if the day is so cold that I close it off to get some cabin heat quicker, and forget to open it again before takeoff. If it's that cold, half cooling will probably do. And in any case, it is along the same lines of not selecting the tank with fuel in it. Run-up checklists are there for a reason.
4) I haven't been able to imagine a situation where I would have closed it after reaching altitude, and then suddenly need more cooling. At worst, I say a lot of nasty things about Bowden and all his foolish ideas for cheap control cables as I power back to make a precautionary landing to buy another one. Maybe they would be opened before final in preparation for a go-around? Maybe that would be the worst case.
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,|"|"|, Ernest Christley |
----===<{{(oQo)}}>===---- Dyke Delta Builder |
o| d |o http://ernest.isa-geek.org |
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