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stall/spin with a tail boom


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I have been thinking, while looking back over my old Sapphire photos, how well do aircraft with a tail boom recover from a spin? a solid fuselage goes a long way to helping in spin recovery, with some aircraft requiring a lower fuse strake to aid in this area of flight....


i am just wondering, and hope to hear from pilots of aircraft with tail booms just how differently do they handle compared to aircraft with a solid sided fuselage in the stall and low speed area of the flight envelope?



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Are you asking from a structural point of view, or as a 'keel' area question?


Aerodynamically any keel area of a fuselarge, either in front of or behind the centre of gravity, is trying to resist the yawing motion found in a spin.


Additional strakes on a fuse resist more.


From a structural point of view, a 'boom' body usually implies a tubular structure.


You should remember that in normal flight, the tail of an aircraft carries a download to counter the pitching moment of a wing that has a stable balance point (forward).


This pitchng moment gets stronger as angle of attack is increased near the stall, (all that up elevator is doing something!)


Without knowing the real numbers, I would suggest that the yawing load on a fin/rudder trying to recover from a spin would be similar to that being imposed on the tail trying to hold the stalled attitude (for the spin).


That covers the 'bending' load on the fuse tube, however a more worrying load on the tube is being created by the fact that usually the fin and rudder are mounted above the tube (more-so with a 'T' tail) which is then applying a twisting load to the fuse tube.


I have seen footage of Sapphires and Drifters doing rolls and spins, but I'm not sure I'd be that game myself.


I could point out however, that the 'Ultrabat' was derived from the Sapphire!





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Guest micgrace



I don't believe tubular structure hasmuch to do with entering a spin or recovering. In fact, I tend to think a fuselage may make recovery more difficult by shielding.It is more likely to be a function of thedesign. ie how much "shielding" is provided by rudder versus elevator when entering an incipent spin. Easy to get out of on Drifter and totally conventional.


As for a Drifter, it is actually quite capable of quite spirited aerobatics (within limits of available energy) and recovery is conventional and quick. Barrel rolls easy, even seen a hammerhead done (and please don't ask who,did take that to VNe to get sufficent energy)


Conventional stall in Drifter (not power on, which is much more violent and prone to wing drop) is almost a non event but you know it's a stall unlike, say an Allegro, which results in little more than mild height loss and a bit of buffetting.


It is actually illegal to do aerobatics AND THIS INCLUDES SPINS in RAAus a/c however the potential is there.


Conditions are great I'm off for Driftering. Might get in a perfect day for once instead of landing/takeoff in 20+ crosswind (Drifter max crosswind component 15K, so they say)


Micgrace :)



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Thanks for the answers, i was thinking more along the lines of aerodynamic properties of the tail boom, i was under the impression that a spin in a tail boom type aitcraft, eg drifter, sapphire etc, would be more difficult ? or easier to recover from a spin? as a result of its tailboom setup.


i was thinking a solid sided fuselage would help control the yaw movement during a spin? or even in level flight,


i remember the early jabirus had a little tail wagging going on in turbulance! and was thinking was that a fuse shape problem or vertical stab issue?. looking over the sapphire pics, i started wondering the same thing again, but in a spin situation, not that anyone should be playing with spins in ultralight aircraft...


the reason i was looking over some sapphire pics, well the house isnt selling in the depression in NSW, and the Savannah will have to wait a little longer, but i can afford something like a Sapphire or Vampire in the immediate future... i have been grounded long enough..



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