RE: gp lancair wings snapping
 

Nikolay ... yeah, EP is about the novelty factor, I am fully EP now and I am doing it because its clean and I am lazy. You are incorrect to say that the batteries are good for 30 cycles. A branded good battery is good for about 70 cycles if you pull it at MAXIMUM discharged rate. Again, 200 cycles is possible if you are hardly pushing it, I mean hardly, something we all will not be doing. On the average I say they are good for 100-125 cycles. Hence, glow is cheaper.

Sportflyr - I have got an 80" CAP 232 up in EP ... Lucky I don't have kids!

Now back to topic ... in Malaysia I have seen maybe 6 Lancairs and not one has had a wing failure ... aren't we lucky!

RE: gp lancair wings snapping
 

no you are correctly assembling these. the wood joiner and butt gluing is not enough. i have a saito 80 and fly at half power. its not e powered cause this engine start the first time all the time

RE: gp lancair wings snapping
 

No doubt. Our wings are exposed to just about every form of dynamic load. Compression, shear, torsion, tension there is no argument there… But glassing the center inch or two of an ARF wings’ sheeting is just going to help any potential failure move outboard by that amount. A properly mixed and cured epoxy joint is NOT going to fail on these models, THE ADJACENT WOOD WILL. If it makes you sleep better at night knowing the center 2 inches of your wing won’t break, it’s all good.

RE: gp lancair wings snapping
 

Why can't I see the wing joiner spar in any off the pictures a good glue joint is 20 times stronger then the wood itself yet it appears to have pulled out not broken off
that could explain the failure

maybe I can't see enough in the pictures do you have one of the side looking into the wing

RE: gp lancair wings snapping
 

As far as glassing well there are plenty of 25- 40% planes that have 2 piece wings butted to the fuse on the tube spar and they do violent manuvers with no problem so I'd say myth busted

RE: gp lancair wings snapping
 

Hi Tianci,

Thank for the comparison. Surely for smaller planes EP is better but this "bird" is
a bit too big for the current prices of the batteries.


Hi Everybody,

Because racing Lancair is on my mind what do you say if I go on a overkill, as mentioned,
to use fiberglass all over the structure of the wings and tail, also on key points of the fuse and
"nicely" place 26cc Glow engine; what do you think will happen based on your experience,
would it fly like a pylon racer too ? In fact there were couple real size Lancair on Reno ...
so what about to try to get in Scale-racing with this one ?

Cheers,
Nikolay

RE: gp lancair wings snapping
 

Rube, you could be very right. I received this model built, was sold very cheap
by the owner of the LHS that I worked for, ($100.00 for plane, flight electronics, and brand new
.61 FX w/ in-cowl muffler).

When I received it, the wing had already cleanly broke the bond
between the wing halves.If you stressed the two halves over your knee,
you could see the seam separating ever so slightly. This is when I decided to
glass the center section immediately before I ever fly it.

The wing was also joined with a polyurethane adhesive instead of epoxy. Either
it did not seem like a good glue or it wasn't applied right. Not to mention,
it had a not-so-clear incident history, but did have scuffs on the tips
from a grass field!:eek:

Anyway after seeing this guy throw his all over the place yesterday, I am
ever so compelled to just buy another one and of course, assemble it
myself. He has an OS FS.91 in this one and it flew relatively
tight loops and patterns quite well. It also had a locally built "fults" type
nosewheel which improved his ground tracking immensely.

I miss it dearly![&o][:o] :D

RE: gp lancair wings snapping
 

Here 'ya go Skiman, doesn't look like a lotta glue there! :eek:

RE: gp lancair wings snapping
 

i started this thread. the reason was as i stated earlier that several months ago i saw another gp lancier had wing failure just like this one on its third flight. it had no previous damage. also about that same time there was another forum where a couple people posted that they had wing failures on the gp lancier. i remember this because i was planning on buying one at the time and after reading those post's i changed my mind.

RE: gp lancair wings snapping
 

I perfer slow cure epoxy 45-60 min for wing joints it gives the glue plenty of time to soak into the grain it doesn't hurt to run a woodpecker over the wood either

RE: gp lancair wings snapping
 

i used stronger wood for my joiner. 1/4 ply aircraft grade. Look at any instruction sheet to a kit built plane and you always glass the center. it does make a huge difference. I fly mine on the saito 80 after a full power t/o i throttle back to half power and that is plenty for loops and rolls. with a long tapered high aspect ratio wing which is thin, you must be very careful on loads applied. I have seen guys who just tape the center together with no glue! insane
Tube spars are much stronger therfore are designed to remove the wings. Again how many overpower the aircraft and do aerobatics, it is a civil private aircraft. On the box is does mention aerobatics which is silly the real aircraft is not designed for it

RE: gp lancair wings snapping
 

I just looked at two greatplanes kits and two goldberg kits and no mention of glassing anything
It sure might help but it's no replacement for a well built/glued main wing spar

RE: gp lancair wings snapping
 

Having examined the inside of my Lancair wing thanks to a fence leaping up at it, I can assure you the spar material is "marginal" for this span/weight (25 years flying thermal sailplanes if you want to know...). I repaired it and still fly it regularly - love it - but certainly keep the G's to scale levels.

A metal plate mounted to bridge the 2 main UC mounts is a good idea though - stops landing forces trying to pry the wing join apart. Glassing the centre won't stop the spars snapping, just define the likely snap point!:D - i.e. right where the glass stops.

Cam

RE: gp lancair wings snapping
 

ok i been building designing model airplane for over 30 years some have been in magazines a plug in wing and a one piece wing are 2 completely different things the joiner tube is the spar !! if the lancair is snapping wings its for 2 reasons a bad desingn or poor construction as far as glassing the center section it will add a tremdious amount of strength the sheer webs go verticle always have always will i use to build professionally from scale to giant scale 3D but i dont have time any more there is a book RCM use to sell it was called desinging and buiding rc airplanes i think alot of guys here would benifit from reading it

with the advent of all the arf out there most people don't know what holds a plane together i only know of a few kits with one piece wings that were not glassed but hey i only have about a little over a hundred buids to my credit

JIM

RE: gp lancair wings snapping
 

thanks DEADBEAT building 30 yrs too

RE: gp lancair wings snapping
 

Glassing a 1-piece wing's centre join reinforces just that - the centre join. It adds NOTHING to the unglassed wing beyond the bandage, so if the wing is inherently weak - as is possibly the case here - then it will still break outboard of the bandage/joiner.

If you are joining 2 structurally sound wing panels, then a bandage certainly adds strength to that join, as Deadbeat points out. Most of the failures reported on the Lancairs have been where the wing brace ends, therefore the basic structure is failing where it has no joiner to help take the loads.

I'm not discouraging glassed bandages on centre sections, just don't want people to expect this makes the WHOLE wing somehow stronger! Sure, there's all the other issues like poor gluing to add in, but at the end of the day don't think a glass bandage will ELIMINATE this wing's shortcomings - only a stronger spar construction will do that.

Cam

BTW joiner tubes are not ALWAYS the spar, as implied - but a hollow spar CAN be used as a joiner tube sometimes.;)

RE: gp lancair wings snapping
 

Now that Skiman pointed it out, I also have a hard time finding the actual plywood wing joiner in any of the photos. Did you find that piece amongst the wreckage, if you did it looks like it probably had no epoxy connecting it to the main spars from what I can see of the photos.

Otherwise maybe the guy that built it found it at the bottom of the box AFTER gluing the wings together.....thus the $100 deal you got!:D

Rube

RE: gp lancair wings snapping
 

Geez, some people are just set in their ways...

I really don't want to brag about my experience in the aircraft industry or model air planes. Lets just say that when I built my first free flight I also knew... Smoking was good for you, rock 'n roll was bad for you, my kids would be living on the moon, you had to glass the center section of your wing and I'd never see the Cubs win a World Series.

Okay so I was right on the last one...

RE: gp lancair wings snapping
 

Rube:

The wing broke outside the joiner, at the side of the fuselage. The joiner is still there but it is hidden behind the rib. The failure was the bottom main spar cap failing in tension at the end on the joiner.

I'd say camdyson is right. The spars are undersized.

Jim

RE: gp lancair wings snapping
 

No, like jrf said but just outside of the stbd. wing seat. The wing suffered trauma
during a near runway tip-stall during a fairly windy day. Should have went around.
she got picked up by a sudden gust, tried to maintain control and bring it down then...WHACK!
She tip stalled suddenly and when that wing hit it was obviously worse than it looked.


I felt I certainly got my 100.00$ worth. This plane taught me a lot about differences in flight characteristics
of scale and non-scale aircraft and I still have a recently crashed, but perfectly operational .61FX.
(that cowl saved the motor for sure) Not to mention all the Hitec gear on her (all but two servos survived):D

RE: gp lancair wings snapping
 

Deadbeat,

Just a little about me,

I do composite layup for aircraft for a living. I've been flying RC for about 7-8 years and my only experience
building was when I built a Bridi Trainer.40 in say 1980-81.

Built beautifully but then a little brother was jumping on the bed where my newly covered
(in Super Monokote) bird sat. [:@]You know what happened next! [:@]

I've been into aircraft and aerodynamics since I was six and saw my
first RC airplane.

This was back in a time where nobody was willing to help newbs especially
young ones and Futaba sets were $400 for basic 4-channel setup.
I was devastated and left the hobby through puberty and
young adulthood. It was through my introduction of the HZ Firebird II
that lit the fire for me again and I've been flying since.

The Bridi did not require any shear web for it's construction so forgive
me if I'm not versed in this type of wing. With that said,

It really sounds like your talking down to people more than trying to understand the problem.
The "ARFERS" comment is totally unnecessary and I feel if you didn't fly ARFs yourself
you would never set your eye on the subject. As much as I would LOVE to have the tools,
area and time to build. I just don't have either so I choose to buy ARFS. This doesn't
make everybody unaware of "what really holds an airplane together".

RE: gp lancair wings snapping
 

sportflr after reading the thread again and rereading my post . if it came across that i was talking down to the guys that fly a arf you have apologies that was not my intentions . as far as being set in my ways that i am . the book im talking about is a very good book if you know how there built you can do a respectical repair job if need be ! 'in a 2 peice wing the tube spar carries the load as it goes through the fuse . so it is part spar part joiner the root has the most stress . years ago when the midwest cae out with the 300 s the were shedding there stabs so alot of guys would put in tail braces and carbon fiber . that wasnt the fix it was flutter that was ripping the wings off . as far as me not flying arfs i have flown many of them and have repaired more than a few. im wateing on my EXTRENE YAK 88 in. 54 as we speak. if you read my post i said the wing will snap for 2 reason's poor design or poor contruction . im going to add one previous damage .

JIM

RE: gp lancair wings snapping
 

No apology needed ...clarifications are MUCH better!;)

I will most definitely check out the book. I wish I was
more familiar with the airplane from an assembly pointbut,
I did not assemble this one. I didn't want to risk separating
the wing and started over out of risk of breaking the joiner
/ ribs or both. Now that's a trick I'd like to learn. With this wing being
secured with polyurethane glue, could anything safely soften it
as to take the wing apart?

Congrats on the (EF?) Yak 88...that's a sweet one! Yellow and black or clown colors? I love the
Yak 54e...the 88's baby brother![8D]

RE: gp lancair wings snapping
 

the yellow and black im looking at engines now i fly at sea level so cal but will be taking it to Colorado Springs when i visit my son . so im looking at the 60cc motor . i heard you lose 20 to 25 % power at 7 to 8 thousand feet

Regards JIM N

RE: gp lancair wings snapping