helijj

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Hi everyone! This week I am going to buy a GP Lancair. I have read many articles about the wing breaking on the air. " I don't want that to happen to me!, So I want to make sure to get all that I need to finish my new baby. I already email Paul ("GP"New Spirit! Lancair) about the subject and he told me that he sandwich some thin carbon fiber ribbon between the two halves of the wing joiner. Can someone please tell me where I can get the thin carbon fiber ribbon? and Can some one tell me how to do it?

Thank you guys

AQ500

I have now built four Lancairs, one for myself and three for others. Every time I have glassed the center of the wing with three layers of light glass with different widths. All of them are still flying and I fly mine hard with snaps and 90 degree bank turns. Not a wing failure to date. One has been flying since the model came out. I would recommend removing the center section of the wing covering, the fuse is fairly wide and you won't ruin the finish, and glassing it. I also bought a roll of the covering on the bottom side and recovered the bottom after I was done.

The wing will be the strongest if you bond the upper and lower wing skins from the right wing to the left wing. On this particular wing the balsa sheeting probably is the most important part of the wing structure and probably carries the majority of the loading (behaves more like a foam core wing with the skins in tension and compression). If the wing skins are not bonded in the center, that little wing joiner has to endure a good amount of bending, and then all of that bending is transferred to the spars and a rib or two with glue, then from the spar and rib to the wing skin. The reason there are so many failures is that there is a lot of stress funneled in that area with the stock set up. I believe that you can reinforce the joiner, and it probably helps a lot, but it isn't as effective as it is believed.

I have seen wing failures (not Lancair wings) where the joiner did not break, but broke out of the wing. Either glue failures, or the structure around the joiner broke. Glassing the center will almost eliminate those failure modes.

Just a suggestion that I would recommend doing......I'm sure others will say otherwise. It is not as easy as reinforcing the joiner, but I spent too much money on this plane to trust the stock set-up.

The plane is incredible in the air and you will love it, heck I want another one with a 4 stroke on it and maybe retracts!

helijj

My Feedback: (5)

Thank you for the reply.... I think I download some picture from this forum (I don't know if is yours but, the point is that is the same thing that you are recommending me. The first picture I can see that the wing is been prepared for the fiberglass coat. The other thing that I see that really helps is the Custom made landing gear. I see that this landing gear is not separate like the normal one that comes with the kit. This will help stiff that wing division.

Other thing that I was thinking to use in combination with the epoxy,using microballom on the epoxy mixing.

Other question:What do you mean wend you say that you use 3 different size of layers of fiberglass? Can you tell me what is your presider to do that?

AQ500

Not my picture, but that is what I do.

I start with a thin strip (like 2-3 inches) and the next two are proggressively wider. If I used three pieces of the same width or a thick piece of glass, there would be a noticeable bump where the fiberglass begins and it would take too much sanding to smooth it down. I let it cure and then sand it down just enough to smooth it out. The reason for the multiple layers is that when I sand I probably destroy most of the last layer.

I thin down 30 minute epoxy with alchohol and use that for my resin. I have used polyester resin, but it is too stinky. The alchohol will extend the curing time and weaken the epoxy, but it retains more than enough strength. It will help you use less resin and flows better into the glass and wood. I use a credit card as a squeege to get rid os excess resin. Discover sends me an envelope almost weekly with a blue transparent fake credit card. That is what I use and I thank Discover card for porviding me with free tools. I guess it isn't junk mail if it is usefull.

I glass the center section of all of the wings that I build. I have never experienced a wing failure in 14 years of flying.

Just some other helpfull tips:

-Do not mount the cowling as per the instructions. Add cowling block like you can see in the picture above. The stock method has you screwing a small wood screw into the firewall. The plywood splits and the screws will not stay there for the life of the model.

-I slipped an oversized wheel collar over the nose struct and it is mounted in the widest part of the nose fairing. I have a long screw in it. The fairing is then stuffed with quilt batting and glued together. The little fairing broke lose on the first two I built and spun freely. The wheel collar, batting trick has cured the problem.

-Make sure the flap servos are mounted the same distance from the flap. I built one wing where the flap servo mount cutout varied 1/4 of an inch from side to side. This caused differential throw and the model would roll when I added flaps. So measure the location of the bays before you mount the servo. If they are off, you can fix it in the position that you mount the servo.

-Eyeball or use an incidence meter when assembling the wing and after it has cured. One of the four had a severly warped wing panel. With the long wings a little twist will have more of an affect on the way it flies.

-If you cut out the side of the fuselage, make sure that you reinforce it well. I have seen people that cut out the cargo door for radio access. It weakens the plane a lot more than it looks. The structure goes from an "O" to a "C". To see what I mean, take a thin tube and bend it and twist it. Now cut a slit on the side and do the same thing again.

-I myself have built all four with dual elevator servos. It is easy to do and will work with no modifications whatsoever, infact I think it is easier to do than a single servo install. I don't want to crash this model due to a servo failure. I spent too much money to let a $15 servo cause a crash. Any model I build that is 60 size or bigger gets dual elevator servos. I may be a little overkill, but I'd rather be safe than sorry.

jrf

My Feedback: (551)

The basic cause of most of those wing failures was the way they mount the aileron servo in the wing. If not done perfectly, the servo can break loose, causing aileron flutter, which in turn causes wing failure. It all happens in less than a second so many people just assume that the servo broke loose in the crash.

I used HS-85 mini servos (same torque as a standard servo) and built hatch/mounts exactly like the flap servo mounts, but smaller. No wing center reinforcement, no problems, and I am NOT a gentle flyer.

Jim

helijj

My Feedback: (5)

Forget my ignorance... So you start applying that first thin strip (2-3 inches) were the two wing joint and the you over lap the other pieces on each side of that first thing strip?.

*Do you glass the other side to or just the bottom part?
*What sand paper # do you use to sand and finish the wing?
*How you prepare thee wing for painting, and what paint do you use?

I am sorry to ask you so much is that is my first time to do such thing,
and I don't want to ruing it.
[&o]

Thank you

AQ500

No worries....

I start with the thinner strip centered on the joint running from leading edge to trailing edge. The next one is then is wider and does the same thing. I do both top and bottom of the wing. I'll attach a quick drawing.

For sandpaper I would not use anything lower than maybe a 220 grit. Remeber to lay down the glass such that there will not be a lot of sanding needed. After that do the minimum amount of sanding to smooth it out. Use the finest sandpaper you can and try to remove the smallest amount of material.

If this is your first time you will probably want to practice on something before you do it to the wing. Give it a try on an old wing or something and then if it goes well, go ahead and do it.

I didn't paint the wings. I just recovered them using the right color of Monokote. It ends up looking better than what it did because there is no longer a seam in the covering at the joint.

Without reinforcement the wing on this plane is a ticking time bomb no matter how well you mount the servos, even though flutter would definitely do lethal damage and good servo mounting is important. For any given person the wing may hold in tact for years or fail on the second flight. I reinforced one in which the sheeting had cracked right infront of the spar near the center of the wing infront of the wing joiner. The owner luckily noticed it and brought it in. That was one that was very close to failing. A lot of people claim that they weren't doing anything drastic when the wing failed. This is probably due to it being damaged earlier in a tight turn or loop and then it decides to let go later. Not everything fails the instant that it is damaged. They usually say that they were hard on the plane before it failed......

I think the forces in this wing are underestimated by a lot of people. The model is fairly fast and short coupled and has a high aspect ratio. Mine probably does 80 mph flat and level and a lot of the turns are steeply banked. Add that to the fact that it weighs 10 pounds and that creates a lot of bending on the center of that long, thin wing.

I put in 10 years working at the local hobby shop before my career took off. I was lucky in that I got to see what works and what doesn't over time. I was able to see wreckage and see what went wrong. After seeing wreckage for a number of years and seeing what the problem usually is, I reinforce all of the wings that are from ARF's.

helijj

My Feedback: (5)

Wow my friend you really are a great person and great teacher. Thank you so much !.
when I do the job I will post it here. Thank you for your time and your good advice.

helijj

My Feedback: (5)

AQ... I almost forgot to ask you. Do you do the bottom side first , let it cure then the next day do the other side, or you just do it both side at the same time? I imagine that you use the original landing gear, not the custom one?

AQ500

I actually do both sides at the same time and then let it cure overnight. If this is your first time you may want to do it one side at a time just incase something goes wrong. Also remember when sanding it that the balsa sand a lot easier than the glass. So, be careful to pay attention to where the sanding block is at. I do use a soft sanding block.

I have used the stock landing gear on all of them so far. I might give the one-piece a try in the future.

helijj

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Thank you my friend!

helijj

My Feedback: (5)

AQ... What oz. of Fiber glass sheet did you use for the wing job? I went to tower and they have 3 different ones.

AQ500

3/4 ounce will work and will be strong enough. You can use heavier stuff if you want to, but you will add more weight and have to sand a lot more.

helijj

My Feedback: (5)

Ok thank you again!

Ozark Flyer

I have been out of the hobby for about 8 years and just ordered a Lancair coupled with a Saito 100. It hasn't arrived yet, so I'm wondering exactly how deep the wing joiner inserts into the wing, as well as how far could one insert a carbon joiner?

I have some extra 1/4" sheets of carbon fiber from a different hobby and if I could make a joiner that was a few inches longer, that shouldn't hurt anything.

Along with that, I'm planning on fiberglassing the wing center, probably 4" wide. I have a strong metal brake and I suppose that some 14 gauge 6011 aluminum or some 304 stainless (16 gauge probably) would work nicely for some landing gear (I hear it's a 2 piece design, ughhh). With the stainless, you could put some nice color into it with a torch after polishing it. The aluminum would brush good, or polish as well.

I'm leaning towards a Robart front strut on this airplane. The front wire gear doesn't look too stout for a plane of this weight (and nose weight). Any suggestions here?

What is everyone doing for the wing servos? How about elevator?

Has anyone taped the hinge gaps on the Lancair? I would think that it would help with the flutter problem at high speeds (as I'm likely to see with the Saito 100).

Thanks,
JD

AQ500

It's been a while since I joned the wings, not sure on the length of the joiner.

I have used standard ball bearing servos on all of the ones I have built. They fit in the wing bays tightly. Mine has digitals on the ailerons, elevators, and rudder.

I have been using the standard nose strut so far. I fly off of hard surfaces and haven't had much of a problem. If you fly off of grass it probably will be a smart thing to to. I'm thinking of running retracts on the next one with the nice struts. I think that would look awesome in the air.

Sealing the gaps wouldn't hurt. I make sure that the surfaces are as close as they can get and that there is no slop in the linkage.

Ozark Flyer

Does anyone know the max length that a wing joiner could be made? How deep would it be able to insert into the wing? I'm thinking of building a carbon fiber ply joiner, as well as glassing the middle 6".

I know this moves the wing stresses further to the tip, but I guess one can just hope for the best.... UNLESS one were to peel back the cover along the main spar and beef it up...

I'm fishing for a speed here... how fast can I expect this Lancair to be with a Saito 100 turning a 3 blade 13x8 prop? How about a two blade?

jrf

My Feedback: (551)

That figures out to about 75 mph in level flight, no wind. Switch to a 13x10 2 blade and you will see 95 to 100.

I my opinion, anything over 75 could cause wing flutter in that airplane, but of course that's only my opinion and with differences in wood density and quality of glue joints, some wings are stronger than others.

Be sure to take videos.

Jim

orvel

My Feedback: (1)

I got a pumped OS91FS in my Lancair turning a 13x8 3-blade prop at 9000 RPM. I know that when put it in a dive at full bore and level out over the field for a low pass I gotta be hitting 90-95 mph--easy! Some guys at the club say I'm over 100! Level flight at full throttle I'd say I'm hitting 75-80 mph, maybe even 85! This is one sleek, fast airplane man!

Ozark Flyer

I'll probably just toss the GPS in there and see how fast she really flies. I may find that the 13x10 3 blade is a better prop than the 13x8 3 blade, and there may be the possibility of a 14x8 or 14x10 2 blade, it will all reside on how well it flies with each change.

To address flutter, I'm going to seal the hinge gaps and remove any slop from the controls. This should be done anyways but I will need to pay some extra attention to a few areas.

helijj

My Feedback: (5)

Hey guys what about glazing the center of the wing, glazing all the wing? That will make a better and stronger wing.