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#1
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Tail Wheels & Tail Booms snapp'n
I was warned about the possibility of a glassed on tail wheel possibly being the deciding factor in your tail boon snapping off in a extreme ground loop incident, whereas a skid or wheel that is intended to tear off could be the deciding factor in just the opposite happening.
I've left my steel shoe, glued on rubber skid in place, and my super faired tail wheel I made, off. Any spinout or repair people care to comment on the idea of the tail boom slamming into the turf at a high rotation speed with a hard mounted TW. |
#2
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Tail Wheels & Tail Booms snapp'n
On 11/17/2011 2:02 PM, POPS wrote:
I was warned about the possibility of a glassed on tail wheel possibly being the deciding factor in your tail boon snapping off in a extreme ground loop incident, whereas a skid or wheel that is intended to tear off could be the deciding factor in just the opposite happening. I've left my steel shoe, glued on rubber skid in place, and my super faired tail wheel I made, off. Any spinout or repair people care to comment on the idea of the tail boom slamming into the turf at a high rotation speed with a hard mounted TW. Ruh roh! This sort of question is dangerously close to FUDland. (That's FearUncertaintyDoubtland.) All fans of Absolute Certainty should read no further!!! Considered from an energy dissipation perspective, any 'tailwheel mount' that happens to break away from the fuselage dissipates a finite amount of energy from what remains in the moving glider, and in that sense reduces the possibility the next sideways load on the fuselage will have sufficient energy to break the tailboom. That said, side-load-inducing events are by nature pretty much uncontrollable (once underway, dry chuckle), dynamic, and unpredictable...meaning analytical results will always be arguably applicable. The fact is, absolute answers to the posed question won't be found in reality. That said, I know of a Zuni (solidly-mounted, fixed tailwheel, albeit by original design) that has never had a broken tailboom in 2050+ hours. Make of that what you will, but I'm of the school that believes Joe Pilot can far better control the *likelihood* of a groundloop through his actions, than he can the *nature* of any J.P.-induced groundloop. YMMV Bob W. |
#3
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Tail Wheels & Tail Booms snapp'n
On Thursday, November 17, 2011 9:31:36 PM UTC-5, BobW wrote:
... That said, side-load-inducing events are by nature pretty much uncontrollable (once underway, dry chuckle), Stick forward to lift the tail as a groundloop develops will always reduce the possibility of the tail digging in (and tailboom damage). Remember to get the stick sharply forward next time you groundloop ! Best Regards, Dave PS: I wish I had a video of an ASW-22 groundlooping for the umpteenth time (failure to dump on one side). The pilot was quite accomplished - lifted the tail just as the tip hit the ground. No damage but one humongous cloud of dust... |
#4
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Tail Wheels & Tail Booms snapp'n
This is why it's very important to apply a large quantity of butter or
margarine to the circumference of your tailwheel before each flight. The butter reduces the side loads and thus prevents the tail boom from cracking. On Nov 17, 3:02*pm, POPS wrote: I was warned about the possibility of a glassed on tail wheel possibly being *the deciding factor in your tail boon snapping off in a extreme ground loop *incident, *whereas a skid or wheel that is intended to tear off could be the deciding factor in just the opposite happening. I've left my steel shoe, glued on rubber skid in place, and my super faired tail wheel I made, off. Any spinout or repair people care to comment on the idea of the tail boom slamming into the turf at a high rotation speed with a hard mounted TW. -- POPS |
#5
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Tail Wheels & Tail Booms snapp'n
On Nov 17, 4:02*pm, POPS wrote:
I was warned about the possibility of a glassed on tail wheel possibly being *the deciding factor in your tail boon snapping off in a extreme ground loop *incident, *whereas a skid or wheel that is intended to tear off could be the deciding factor in just the opposite happening. I've left my steel shoe, glued on rubber skid in place, and my super faired tail wheel I made, off. Any spinout or repair people care to comment on the idea of the tail boom slamming into the turf at a high rotation speed with a hard mounted TW. -- POPS The currently popular large tail wheels do a good job of helping keep the glider straight which seems to help avoid the problem in the first place. Once they are seriously sideways in a true ground loop, they slide reasonably well. Once the tail digs in, the boom breaks. Does a break away skid/tailhweel avoid this? maybe -sometimes. I've put a number of modern tailwheels in older skid equipped gliders and every owner has bee happy with the improvement. FWIW UH |
#6
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Tail Wheels & Tail Booms snapp'n
Hmmm,
I have repaired maybe 15 broken booms including 3 that I have cardinal knowledge of and it is my humble opinion that the tail wheel dragging sideways has little to do with snapping the boom. In all 3 of my personal recollections, the tail was off the ground during the event (2 had wheels, 1 had a skid). I watched a Discus come as close as it could to breaking its boom when it landed beside me, only a bit deeper into the barley field at Camby, Ca The left wing tip caught a clump of barley and around it came, tail off the ground, spun 180, T-tail laid over a good 30 degrees, then the boom came down and she just sat there and shook for a moment. What determines weather you break the boom or not is speed, ground loop below 40 knots and you will probably come out unscathed, do it above 40 and she's likely to break (Libells reduce by 10 knots). What's really going on is simply this, The wing can take it quite well because it has a spar, the boom doesn't and one side goes into compression while the other is held in tension, compression looses and buckles inward, do it hard enough (speed) and she snaps off, tail wheel had very little to do with it. As always, just my humble opinion, JJ |
#7
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Tail Wheels & Tail Booms snapp'n
JJ,
If I may add.... The torsional load of the T tail, especially with lead weight installed is a big factor as well. I do not believe the style of tail wheel is a factor in tail boom fractures. The style of landing, on the other hand... Rex |
#8
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Tail Wheels & Tail Booms snapp'n
With all that logic and experience talking....can't deny that having something there that comes unglued under stress (tail skid) is a better situation than something permanently mounted (tail wheel) that increases the dragging (sideways) forces. Bare fiberglass slides better. In my experience, I've had several tail skids come off during off field landings....did it save my boom? dunno....but, the thing didn't break!! (Hard to find those things!!!) What's probably more important is to avoid any weights (batteries, ballast...etc) placed anywhere up high in the fin that increases the torsional twisting motion. Mike Adams cautioned me against this when I bought my first LS-6 from him. I've always put my balance weights down low back there, using the factory mount at the lower rudder hinge bolts.....and no tail batteries, ever. J4 |
#9
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Tail Wheels & Tail Booms snapp'n
On Nov 19, 2:24*pm, "John" wrote:
With all that logic and experience talking....can't deny that having something there that comes unglued under stress (tail skid) is a better situation than something permanently mounted (tail wheel) that increases the dragging (sideways) forces. * Bare fiberglass slides better. In my experience, I've had several tail skids come off during off field landings....did it save my boom? *dunno....but, the thing didn't break!! (Hard to find those things!!!) What's probably more important is to avoid any weights (batteries, ballast...etc) placed anywhere up high in the fin that increases the torsional twisting motion. * * Mike Adams cautioned me against this when I bought my first LS-6 from him. * I've always put my balance weights down low back there, using the factory mount at the lower rudder hinge bolts.....and no tail batteries, ever. J4 I believe the issue is that pneumatic tail wheel will provide much more grip on pavement and therefor provide better directional control. On grass or gravel, either work about the same. In a cross wind landing ,the only way to keep her pointed down the runway is to hold back stick which gives the pneumatic wheel max grip. In the Genesis I force the nose wheel down with full forward stick in order to give it max grip, but even then when my speed equals the wind speed, she weather-vanes into the wind. Then I must lower the opposite wing and the little tip wheel gives enough drag to keep her doing my bidding. Landing a flying wing in a cross-wind has been an educational experience, but I have once landed with a 30 knot direct cross-wind and walked away unscathed!. Cheers, JJ |
#10
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Tail Wheels & Tail Booms snapp'n
Guys - Tail up prevents catching on rough ground
and reduces side-load on tailboom if in crops. Tail up if you start to groundloop ! See ya, Dave |
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