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Lancair Wing Failures

Old 01-27-2004, 02:49 PM
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iFLYrc_Vic
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Default Lancair Wing Failures

Looks like there are quite a few owners of the Lancair that have had unexpected wing failures. I am starting a new thread to allow folks to post messages that are not buried at the end of another thread.

I have been flying my Lancair very scale like with no abrupt maneuvers like snap-rolls or high speed tight turns. I used the stock equipment and did not glass the wing joint. I may be "a failure waiting to happen" but so far I have not seen any signs of failure. I have an OS 91 Surpass II with a 3-Blade prop (11 x 8 I think). I perform high speed low passes (beautiful thing to see) by making a shallow dive and then a gradual climb out at the end of the field as I back off the throttle.

I am glassing the wing joint on my Patriot version of this plane just for safety sake. I hope someone can come up with a good reason why there have been so many wing failures.
Old 01-27-2004, 04:09 PM
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iFLYrc_Vic
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Default RE: Lancair Wing Failures

I hate to be the first to reply to my own message but I had some thoughts on this wing failure issue. On one of my early flights I had a "not so smooth" landing while learning how to use the flaps (a thread could be developed on that topic also). The landing ripped out the right landing gear. I posted a message on how flemsy the gear was attached and how I re-enforce the installation.

Now that I think about it, the outside landing gear mounting screws went right into one of the ribs. The inside screws are just outside the ribs that join the wing. For those pilots who had wing separation, where EXACTLY was the break. I remember one message that said his wing broke cleanly just outside the center ribs. Another post said his broke a little further out. Were these breaks in line with the gear mounting screws? I may be out to lunch here but its worth a thought.

One of the pilots, KKSHAZZAM, posted that he had been perfroming snap roles at the top of loops. This certainly put extra stress on the wing. He also posted a solution of placing an aluminum plate between the landing gear and the wing to strengthen the joint. That is probably a good idea and will not add substantial weight to the plane AND it is close to the CG so you should not have to re-balance the plane.

My two cents...
Old 01-27-2004, 04:39 PM
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splais
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Default RE: Lancair Wing Failures

I have one of the posts in the Lancair Pics thread.

I quote from the Great Planes PR on this plane: "excels at many aerobatic maneuvers including loops, spins, snap rolls, and inverted flight". The Lancair is a beautiful and sleek plane that just cries out to be flown at the limits. I believe the construction of this plane is not up to the afore-mentioned statement without substantial modification.

I also wonder if the ease of overpowering this plane also contributes. A 90 two stroke or 100 four stroke exceeds the manufacturers limits which it appears should be considered a hard limit.
Old 01-27-2004, 06:13 PM
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ringram2077
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Default RE: Lancair Wing Failures

I wanted to see if GP had a position on this issue so I gave them a call today. The person I talked with said that they (GP) did not design this airplane (guess someone else did ??) but there was not a problem with the wing joint design. I asked about the instances I had read about on this forum and he said there were cases where too large an engine had been put on the plane that resulted in a wing breaking, hhhmmmm. I explained that I was about finished with my Lancair and that I had used the stock dihedral brace but had also glassed the center section. I also stated that I would be REALLY *issed if I had a wing failure but he told me it should not be a problem. He also said that if I were to experience a failure that GP would be under standing and likely replace the plane. Well, go figure what all this means ??????

Richard []
Old 01-27-2004, 06:22 PM
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SDCrashmaster
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Default RE: Lancair Wing Failures

It seems that most tof the incidents involve the joiner. I would suggest strengthening the joiner by either cutting a new one out of Aircraft grade ply or by snadwiching a layer of carbon fiber between the two stock pieces. Our first Lancair was built according to the instructions with no mods. The wing had nothing to do with it's demise after 30-some flights. Our second utilizes the carbon fiber sandwich joiner as mentioned above.
Old 01-28-2004, 02:04 AM
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Flying Rubbernutz
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Default RE: Lancair Wing Failures

SD......at least I think a little like you. Picked up a piece of carbon fiber tday to do just that. Thin, light and after an iron on then some epoxy, it will definatly do the trick.....did you need to sand the joiner after or was it a good fit?.....thanks Jeff
Old 01-28-2004, 07:59 AM
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H. Wayne S
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Default RE: Lancair Wing Failures

Ok, I have one with a Saito 100 on it. How do I go about "glassing" the wing joint. I have already experienced looseness in the firewall. I had to go back and coat the interior with epoxy and cloth to firm it up. Like ringram I'll be pissed if the wing fails now.
Old 01-28-2004, 08:33 AM
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ringram2077
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Default RE: Lancair Wing Failures

As far as glassing the wing joint, I got some 4" glass cloth at the LHS. They had a couple of different weaves and I got the coars weave, kinda heavy looking compared to the other. I then stripped back the monokote to match the cloth width. Used the hot soldering iron method the cut the Monokote nad it work well. I decided to use epoxy since I did't have any FG resin. I coated the bare wood with exopy (slow dry), layed the glass cloth on and put epoxy over the top. The very front of the wing that butts up the the fuse got covered also. I did not cover the area where the LG struts connect .
Richard
Old 01-28-2004, 09:36 AM
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Default Landing Gear and Wing

I was looking at the landing gear on the Internet and noticed that it's a two piece set up. I wondering if this also part of the problem. Two piece landing gears, basically try to rip the themselves out of the wing when a load is present. I especially see this on a hard landing. Where as a one piece gear evenly spreads the load thoughout the area where it's attached and then I would imagine the load is eventually travels throughout the rest of the wing.

When I start mine, I'm going to look into a one piece gear and beefing up the mounting plate where th gear attatches to the wing, plus fiberglassing the center section.

I have a World Models Midget Mustang that I fiberblass the center section and have been flying it for years and no problems. I did however go in and reinforce the landing gear area with additiona epoxy.

I agree with you all that an aircraft grade ply joiner has to be made and put in the wing.

I'll be talking to www.tntlandinggear.com/ whose the closest hobby shop that I'll shop at and see if they have a replacement gear for lancair or probably just have them bend up a one piece for me.

Agian, this is just my two cents. I'm a wannaBe Engineer.
Old 01-28-2004, 09:38 AM
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MidMadn
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Default RE: Lancair Wing Failures

Just another option -

My brother and I just built his Lancair.

We didn't see any easy way of glassing the bottom of the wing without making a mess of it. (especially around the landing gear attachment area)

The two mods we did do were -

We filled the elongated hole in the root rib with a small piece of light ply so we could fill the voids with epoxy. This makes the wing joint solid. It's not just holding by the small outer strips of wood.

The biggest improvement I feel that we did was to make an aluminum joiner plate for the landing gear. This is a .100 thousands thick piece of aluminum plate cut and drilled to go over both landing gear halves in one piece. Like a huge washer. We also stepped up one size on the screws to #6

You can see it in this pic. (It really needs to be polished or better yet painted to match though.)



Jack
Old 01-28-2004, 09:39 AM
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Default RE: Lancair Wing Failures

See, I thought that two piece gear causes problems!
Old 01-28-2004, 01:24 PM
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splais
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Default RE: Lancair Wing Failures

You are correct. Two piece landing gear are one of the great ripoffs/screwups, depending on your point of vew, in ARFs or any plane. Two piece gear apply destructive forces directly to the fuselage that are more evenly distributed with a one piece gear. With a two piece gear all the landing forces are directed through just the two screws/bolts holding each piece to the fuselage.
Old 01-28-2004, 01:54 PM
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Default RE: Lancair Wing Failures

ORIGINAL: H. Wayne S

Ok, I have one with a Saito 100 on it. How do I go about "glassing" the wing joint. I have already experienced looseness in the firewall. I had to go back and coat the interior with epoxy and cloth to firm it up. Like ringram I'll be pissed if the wing fails now.
Often, once a firewall begins feeling loose, you need to pull the firewall out, clean up the joint(s), THEN dowel pin it back into the airplane with epoxy as the glue. It is quite possible it feels fine now... but is just as weak (or weaker) as it was whenyou first mounted the engine (and you thought it was fine for the oversize engine then...)

Patches such as described fail quite often...
Old 01-28-2004, 02:46 PM
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Default RE: Lancair Wing Failures

Greetings guys! Its nice to know these things before the disaster happens. The big problem is how do you go about reinforcing the wing joiner when its already epoxied ?. I make it a point to always reinforce the firewall irregardless of how it arrives from the manf. [I.E. Hanger 9 ] and yes , the LG reinforcement plate is a good idea. I have twenty-two fully operrational RC planes and have only lost a couple to mechanical failure in just over five years. Talk to me on this joiner problem, any ideas. A little bit of old age is slowing the thought process down. Seeya, MJS
Old 01-28-2004, 05:42 PM
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splais
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Default RE: Lancair Wing Failures

I am thinking that a strip of carbon fiber under the bottom/top covering along the main wing spar would help a great deal for an already completed wing. but I don't think it is necessary to panic here. If the plane is powered within the recommended range and flown conservatively (can still be beautiful) you probably should not have a problem unless a lot more people chime in with broken wings. It's nice that GP will replace the plane if you beak a wing. Now how about the spinner, engine, servos, and receiver that were all smashed to heck and gone on the crash I saw.
Old 01-29-2004, 08:09 AM
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Default RE: Lancair Wing Failures

Were using a Saito .100 w/ 14-8 prop. I slow down into my turns/banking and then speed up out of them. It sure is annoying to have to correct the manufactuers short-coming on quality. these things are not tested for durability. As for landing gear problem, Im one of the smoothest landing RC plane landers around..... but, we'll beef it up anyway. Seeya.
Old 01-29-2004, 09:46 AM
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Default Two Piece Gear

I just acquired a "Scratch and Dent" Lancair, so I can take the landing gear down to www.tntlandinggear.com and get a one piece made up. If all goes as I think it will www.tntlandinggear will be able to sell these as an "off the shelf item."

I'm off work next week, so hopefully my kit arrives tomorrow "Friday the 30th" maybe I can get it down there Saturday or Monday.

Guys email if you would be interested in a one piece gear at [email protected] That way I can tell them at www.tntlandinggear.com what to expect in the near future.

I also have talked to Darrel at www.sierragiant.com about nose gears. He said that he will be making up more a little later on. I did order one of his gears for my Hangar 9 Cessna 182 and it arrived. It is just AWESOMEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE! Worth every dollar and I can see how putting this nose gear on the Lancair will make it a much better hanldng airplane on the ground.

[8D]

I said earlier that I got a "Scratch and Dent" Lancair - I guess it has a crack in the fuse near the fin, so I'll hopefully throw so glass and epoxy at it and be ready to start scaling out this kit.

SD Crashmaster has got some awesome ideas over on the "thred Lancair ES Pictures" check it out if haven't already.


I'm so Excited!!!!
Old 01-29-2004, 12:53 PM
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SDCrashmaster
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Default RE: Lancair Wing Failures

I like the addition of the aluminum gear joiner plate. Ties the whole structure together and is right on the CG. Good thinkin'. Plus I've got plenty of black paint left from the "New Spirit" revamp.
There is just no way that wing could fail with that cross brace on it...at least not at the center joint anyway.
Do fly your Lancairs in a scale manner though. If for no other reason than aesthetics.

"If it ain't scale...it's...well...you know.
Old 01-29-2004, 01:25 PM
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iFLYrc_Vic
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Default RE: Lancair Wing Failures

Paul,
I have a fun fly that I burn holes in the sky with. I have a Sunray (RCM plans) that I go fast with. I also have a few scale planes that I fly in a scale like manner - Cessna 182, Flivver, Ryan STA, Lancair ES. My thoughts are that you should fly the plane for what it was designed. In some very early messages after I posted some info on my first Lancair, someone asked me "if it would snap roll". I was somewhat perturbed by the inquiry as I thought, if you want a plane to do aerobatics why not buy one that was designed for that (Extra 300 or something like that). I know that GP advertises that the Lancair will do some aerobatics but why put it through the extra stress?

Don't get me going on the topic of how one should fly a scale plane - it is simple - fly it like the full scale!!
Old 01-29-2004, 01:35 PM
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Default RE: Lancair Wing Failures

You're "right on" there Vic.[sm=thumbup.gif]
Old 01-29-2004, 05:39 PM
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splais
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Default RE: Lancair Wing Failures

iFly, the only problem is that if you go to the GP site. They don't say it will do "some" aerobatics. They write it up like the plane is a full blown aerobat and they specifically mention you can do snap rolls. All though a good many people do not know how to do a snap roll correctly (which does not mean snapping at full throttle and max speed.
Old 01-29-2004, 08:46 PM
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iFLYrc_Vic
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Default RE: Lancair Wing Failures

SPLIAS,
As I said in the reply, fly the plane like the full scale. Great Planes and manufacturers of any product will "tease" you with implied extras. Be nieve and believe what you see and push it to the limit and get what you deserve. If I paid 3 million for a race car that was advertised to go 290 mph and it broke at 280 mph, I would ask for my money back. When I pay $300 for an ARF and I take it to the limits and it breaks, I don't fret. I say oh well, it was a $300 ARF that I should have backed off a little OR beefed up to take the extra stress. Let's face it, an ARF is and ARF - a mass produce product that is manufactured as cheap as posible. In that regard, the Great Planes Lancair is a GREAT PLANE!! If you want super quality in a plane, build it yourself or have a master builder do it for you.

Sorry to have wasted the ink on this, but this thing about pushing the Lancair into an aerobatic plane just [email protected]#$ me off. I apologize if I have offended anyone with this response.
Old 01-29-2004, 09:45 PM
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splais
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Default RE: Lancair Wing Failures

Not P*&^% in the least. The ONLY thing that even remotely upsets me about this plane is that it is sleek and beautiful and just "cries" fly me fast. If you do not use common sense and get sucked in, you are going to loose this plane
Old 01-29-2004, 10:00 PM
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Default RE: Lancair Wing Failures

What really struck me when I began to look at the Lancair wing closely is how THIN it really is !! And with the high aspect ratio this does NOT add up to a strong wing design. Guess we must come to terms with this fact. I am looking forward to my maiden on the Lancair. I will be careful at first but we surely push the envelope later on. Hey, it's only money !

Richard
Old 02-02-2004, 02:20 AM
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Default RE: Lancair Wing Failures

Well folks, finally put my wings together. Had two of the more experianced builders from my club check it out before the build. They both came to the same conclusion. Not only was the wing joiner feable, but the hollowed out area that comprises the wing root acounted for the weakness. I sandwiched woven glass between the two pieces, and also filled in those hollowed areas with balsa. This in fact added almost 50% more area for epoxy to grab onto. After it cured we slowly added pressure to the joint to check the strength. The only way this wing is breaking is if it flys through a tree. Also recommend joining the landing gear with the aluminum like MinMadm did. This too will add to the overall strength of the wing. Just my 2 cents.... Best to all Jeff[sm=bananahead.gif]

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