"big tail" elevator advisory
08-12-2009, 08:49 AM
gderamel | 'big tail' elevator advisory
Folks who have the â€˜Big Tailâ€™ (of Craig Easter) on your Seawind, I thought Iâ€™d pass along some information and pictures of mine.
Not sure why or how (construction? water?) but the trailing edge of the elevator has delaminated (see pictures) and appears to be the culprit of the elevator flutter that just developed. I canâ€™t definitively say that this weak trailing edge is the cause, but the flutter is definite and nothing else apparent.
Comments, suggestions are greatly appreciated.
Guillaume de Ramel
08-13-2009, 03:54 PM
Ahhhh, that answers the question. I didn't think that the servo would have caused a flutter like that. I have only seen one other big tail and as far as i know he will not be putting it on his plane. He also has the regular elevator.
01-19-2013, 09:02 PM
I have the "Big Tail", that so far has not shown any delam problem. Years ago, Paul Array had a flutter & surface delam problem at the horn to elevator connection--he sent me pics. Inspecting mine, I noted no connection between the shear web of the elevator spar and the rib (shear web) of the horn. I did a 10 ply layup there. There is still a lack of torsional rigidity in the elevator--we're thinking of foaming it.
We had a similar situation to that shown in GDeramels pic in one of the s@#$%! Craig Easter fowler flaps. Foaming it solved the problem, but left a slight bulge. We should have clamped it better. To foam a big tail elevator, I would clamp two 16 ft. 2 x 12s to the surface, drill a 3/4 to 1 inch x 7ft 6in hole from each end, and inject the foam thru a tube connected pressurized foam kit. These kits are used by the power companies to fill and seal underground electrical connections--come with 2 cylinders, hoses and mixing nozzles. I foamed the bottom of my hot tub this way 'bout 40 yrs. ago.
It would be a good idea to make a plywood mockup for a test run to learn how fast to retract the tube.
01-20-2013, 05:44 PM
With all the problems associated with the modified tail, elevator and flaps over the past years, i would not use them!
01-21-2013, 07:24 AM
Originally Posted by Rusty View Post
I have the "Big Tail", that so far has not shown any delam problem. Years ago, Paul Array had a flutter & surface delam problem at the horn to elevator connection--he sent me pics.
I had the Big Tail on my plane but took it off (it almost took me off the planet). Sure, I appreciated being able to bring the nose up at 30 kts, but one thing I'm absolutely certain of is that there was no where near enough engineering and flight testing in its design, not to mention its quality of its fabrication was absolute junk.
I had a tail flutter incident when the elevator trim tab servor broke. John Parks lost 2/3 of his Big-Tail elevator when his mass-balanced trim tab broke off. It's just not worth the small benefits one 'gains.'
If you don't have the original tail, call Dick Silva and ask him if he's got one he can sell you. And be sure to ask him about what the Certified Seawind's flight testing concluded on the 'small' stock tail... it's got more than enough pitch control than Part 23 requires - vindication for him - that the seawind's tail does not need to be bigger.
08-20-2014, 01:19 PM
I have the original tail, minus the 7" tip stretch and 3" elevator addition.
I have a composites expert working for me who used to run a builder assist shop in Southern Ca for Glassairs & Lancairs. He's a pro. We spot & repair the "imperfections" in Craigs S@#$TY workmanship. Everything associated with the trim tab has been beefed up. The vertical tail is reinforced at weak spots. The thing we notice most is the lack of torsional rigidity in the elevator, too few ribs. That flutter mode can't be corrected with mass balance. Next week we will be foaming in two 8' graphite torque tubes that just arrived. The extra weight will be balanced by the extra battery capacity in the nose that assuages my electrical paranoia.
I saw a scary torsional flutter video online of a Cherokee showing +/- 15deg. excursion. Might have been a Cherokee 6 which has extentions on the tips. Might explain the cracks I got in my old Cherokee. Too bad Martin Hollman died of cancer before we could get his help on this subject.
Anyway, it's called EXPERIMENTAL AVIATION.
08-20-2014, 01:28 PM
Don't forget about the piano hinges too! Ask John Parks about them.
04-15-2015, 09:24 PM
My piano hinges are stainless steel, a heavier gage.
Foaming the elevator with 2 x 12s & lots of sand bags worked well, no bulging,some stiffness improvement.
Graphite tubes fit ahead of elev. spar did the trick--very stiff in torsion--solid connection to balance horns achieved, horns foamed & balanced.
Everything but the fuselage primed, ready for paint. Finish engine wiring & scaffold removed, professional helper returns for fuselage bodywork, I wire panel. (Over my head here!)
Health problems. Engine work done. Venturi vacuum gyro & Mech. backup instruments done. Prof. helper now runs composite dept. @ Icon factory, up to eyeballs in work. Professional auto body/a&p/I.A. friend coming to paint instead. Still wiring.
I.A. overseer improves quality, but slows progress. He insisted on rework of nosegear front pivot for grease fittings. I machined custom fittings and modified bearing plugs. After hours of various frustrating approaches, we bolted in just the plugs and glued 1/8" thk V suppts. under. Plugs prealigned, held with a bit of duct tape, reassembled to the gear leg, nested in the Vs turned 5 hours of pain to 5 minutes of play. Wiring on hold. I.A. still nit-picking. Oshkosh in my life time?