Spars for the Swick - Wood or Metal?

[Vasey fan]

Well guys, the time has come to order spars for the project. I know this is a controversial subject, so - who's using which & why? The cost really doesn't factor in to it, as they are pretty comparable in price.

I already know Eric's answer.

[Jim Herpst]

Re: Spars for the Swick - Wood or Metal?

Lately it appears that ASS (Aircraft Spruce & Speciality) has the price and quality edge. I am using them because I can also drive down to Atlanta and with the three hour drive save the shipping/pickup at motor frieght hassle etc.

I heard others on this site say they had problems with Wicks. I find that very difficult to believe as I have used em several times before with out ANY issues. IF you live closer to Wicks I would use Wicks.

[gmackay]

Re: Spars for the Swick - Wood or Metal?

I think the question is metal vs. wood spars. If so, I considered both, but ended up with wood. I found people on both sides, but in the end, the majority said wood was better for aerobtics. They also said that the metal spar gave a stiffer ride, which I didn't want. The other factor against metal was that after looking at the plans, it seemed like you'd need a mill to do correctly, or at least have some machining done.

But getting good wood has been a challenge. I'll be glad to send you a picture of a spar (from Wicks) that I could shove a piece of paper through. After three shipments, I gave up. The story I heard about Wicks is that they had some "turn-over" in the spruce department. (the main wood guy left). I think their quality suffered then. It may be better now. Then the first order from Aircraft Spruce was damaged in shippment. But the rest looks good.

Been gluing doublers the last couple days.

[Jim Herpst]

Re: Spars for the Swick - Wood or Metal?

JEEZ sorry I just now saw the wood vs metal on the post orginally. Without question WOOD ! (

[Vasey fan]

Re: Spars for the Swick - Wood or Metal?

I'm definitely leaning towards wood, just concerned about being able to get decent, close grained spruce. The skinny little webs on the aluminum spars don't exactly give me a warm fuzzy feeling, but I've seen them in action & they obviously work.

[Acroeric]

Re: Spars for the Swick - Wood or Metal?

Sitting home today with sick kids- I just noticed I too had a low grade fever. . . . maybe with some medicine I can finish up the last of my all WOOD ribs ;-)

The wood vs metal question was settled for me after looking at the ability metal has to retain "memory" in that over repeated high stress cycles it looses strength. It's failure mode is instant. Wood on the other hand has no memory and a crack usually doesn't render the wing coming off. I have seen several cracked spars that were flown (not knowingly) for 10-15 years before finally being detected.

I once did an annual on a Pitts- the owner complained of a change to the snap entry and exit that he began to notice several months back. I found the top wing center section to be busted up pretty bad- basically it had cracked in 3 locations but it stayed together. The damage was not due to the wood- it was due to the owner flying a +6/-4 G airplane at +9/-6 G in IAC Advanced. He later told me he had to pull that hard to be competitive with the monoplanes. He had exceeded the airplanes design by a large margin- would metal spars have failed more dramatically? I do know from an engineering point that if they had failed it would have been a total failure.

Any material has it's limits. Either would (wood) be just fine in our airplanes- it basically comes down to preference. I have seen Randy Henderson doing outside square loops in a 1300 pound (empty!) 180 HP clipwing. I have also seen video of Forrest doing a pretty agressive routine in a 180 HP metal spar Swick. Other than collapsed leading edges I am aware of no failure of any clip wing Tcraft ever. There is a weak point in any design- chase it beyond the amount necessary and you end up with a boat anchor-

[Forrest Barber]

Re: Spars for the Swick - Wood or Metal?

Well said , I agree with all comments. As explained before, IF you are doing any changes to plans or going out in left field with design , then Proof test it with sand bags..... plus & minus... this is a static test.

Nothing beats hearing the big bang as they (the factory) hit -9 G's for the Ultimate test of the F-21 fuselage cross tubes when one kicked out and I just grinned knowing that I was not in the airplane.
Or the time we pulled the ends out of the struts during the +9 g loading of the complete wing system
Then just to satisfy MYSELF I did take Leisa Marie "The Super-T" equipped with spin chute and ballast up to 8000 ft and pulled 7.0 G-s positive straight pull, 5 G's rollling pull and the good old 4.0 G's push, I had pop off doors and a good Security 350 chute, nothing broke ( this was AFTER the leading edge fiasco) . I then restricted myself & her to +5 & - 3 ... AND watch out for low level turbulence and slow up a bit during manuvers, maybe not as pretty but safe.
Wood vs. metal ; chocolate vs. vanila ; hmmmm I see virtue in Both!

[Vasey fan]

Re: Spars for the Swick - Wood or Metal?

Eric, the Texas T-Cart weighs 1300 lbs empty!? He's gotta have everything including the kitchen sink in it.

I'm aware of the stress memory thing with metal, it's probably the main reason I fly my C-140 with kid gloves (most of the time). Don't know where she's been taken over the last 60 years.

Thanks for all the responses so far, and Forrest, rest assured that I'm well past my "young & bulletproof" days.

[Forrest Barber]

Re: Spars for the Swick - Wood or Metal?

No way can that Texas T-xxxx weigh that much..... could be Gross.... WE Grossed Leisa- Marie at 1280#.....

[Acroeric]

Re: Spars for the Swick - Wood or Metal?

Nope- I spoke with him at length at Sun N Fun. He said it was right at 1300 pounds empty. Remember- he has a ton of structural mods, pyro, lots of fuel, lots of avionics, a full interior and baggage compartment, metal prop, IO-360, and so on. He and DI fly it to airshows (at least before their son was born) and they wanted it to be comfortable.

[Ragwing nut]

Re: Spars for the Swick - Wood or Metal?

I'm definitely leaning towards wood, just concerned about being able to get decent, close grained spruce. The skinny little webs on the aluminum spars don't exactly give me a warm fuzzy feeling, but I've seen them in action & they obviously work.

There is a guy in Scottsdale that has good quality Spruce. Company is called 52nd Street Lumber. I don't know if he is in the phone book or not but I have the number somewhere if you can't find it. Tell him Mike Redpath sent you.

Mike

[ClipWing_T]

Re: Spars for the Swick - Wood or Metal?

Ralph Pearson at Aero Country Airport had a 180 hp Swick that weighed right
at 1200 lbs empty it was HEAVIER than my 150 hp PA-20 (empty weight).But it flew really good.There is a Swick project at Aero Country that is really different than your average Clipwing t-craft. the plane has elliptical tapered wingtips all metal. The tail looks kinda like a Monocoupe! LOOKS GOOOOD! Don't remember the guys name but he goes by "Zero"at the airport. Flys fro SouthWest.Mike Swick helped him on it some too and it's ready to cover.I asked him about the empty and he kinda rolled his eyes and sighed LOL.

Mike in East Texas

[Vasey fan]

Re: Spars for the Swick - Wood or Metal?

Don't get me started on the Monocoupe stuff. I already talked myself out of the wingtips, but 'Coupe tailfeathers are still a possibility.

I'll look into 52nd st Lumber, thanks.