Zor

Robert,

I do not have the plans (drawings) of this model and might not be very helpful.
The misalignment (lack of parallelism of the rulers) might be due to simply a piece at the rear end of the fuselage to be in a slightly wrong fit. I would not conclude that the fuselage is twisted.

The first thing I would check is the fuselage as a whole unit to see if it is symmetrical to a FLAT vertical geometrical plane. FLAT means that there is no twist in that vertical plane. It is not difficult to eyeball that condition.

One thing to consider is the shape of the main wings saddles and the fit of the wings to that saddle.
I would sit the wings on the fuselage and check how they fit and shape the saddle for minimum gap frem the wing Le to Te. When satisfied with the wing fit to the fuselage, only then would I look at the stabilizer fit and alignment. All that would be needed there is to again sand the pieces so that the stab is parallel to the wings taking in consedration any dihedral that the wings may have.

From your posting I feel that you will glue this fuselage with CA. If so I hope you will double glue all corners with good wood glue creating fillets everywhere.

Can you post pictures of your work that illustrate what your concerns are ?

It would give me a much better chance to help you.

Zor

sensei

As Leroy stated spraying or soaking with water loosens the fiber in the wood. Try wetting the wood with Windex with ammonia, or mixed ammonia and water and see what happens, it's like using kicker an C/A, the process is really accelerated. I have been forming balsa wood this way for a very long time.

Bob

Leroy Gardner

I can't agree more Bob and this may be a good place to explain some aspects of wood, warpage, moisture and related heat effects. So many of our kits come out of factories in humid areas, sit in warehouses for months before we have one in our hands and in some cases the moisture in the wood can even freeze. When we recieve shipment of a kit or building products and get all excited and open it up get all the parts out (just checking condition) and setting them in order on the bench, often leaving them there is where the problems start. They warp and twist caused from climate and temp. change. They should have been left in the box and given a chance to acclimate to their new enviroment or at least after the inspection was done.

In the case of building your wings, your spar is most likely spruce or bass wood which is a very straight grained wood but can still bow and is alot stronger than balsa so it goes into tension. When assembly starts they are the first pieces on the pinning board but they have to be installed in some order, crown up on bottom and crown down on top or vice versa, now they are in tension with each other and never take it off the board without the shear webbs being installed, follow instructions where joiners are concerned. Now put it on a flat surface and lay some magazines on it to hold it down until other wing is done.

Plywood once warped and twisted can make for real assembly issues especially in fuselage bodies, another case of mishandled parts. I always cover and weight those parts right up to the time they are used. Poor packaging can be part of the problem but most of the time it is what we don't do that causes these problems and they can be avoided if you know what causes them.

Moisture loosenes the fiber, heat removes moisture causing cupping, twisting and warpage because most wood is in some form of tension and containes more moisture in one part than the other so protect that from happening. Remember. just because its it's glued together doesn't mean it won't deform if only slightly, covering or painting is it's best protection and even that is no guarantee when stored improperly, remember what moisture does.

I am an accomplished wood worker and plane builder, I know what i'm talking about

Robert hope your fuse. goes together ok.

rkcruit

Hi Zor,

Thanks for your response. I will post pics this weekend when I return home.

In reference to what you said re: the usage of CA, I would actually prefer titebond or some othe glue that won't cause respiratory arrest during application.CA isvile stuff. CA would definitely be quicker and easier to apply, but titebond would give me more time to adjust clamps and make sure things are aligned correctly. Also, you made reference to fillets. Is this just a thicker layer of glue along a joint? What would be your glue preference?? The wood being glued in the fuselage consist of balsa and lite ply.

Thanks.

Robert

sensei

If you have proper ventilation and glue everything with thin CA, then come back with medium CA creating fillets in all corners, you will have a structure as sound as using any other adhesive, and you can assemble it really fast if that is what you desire, one other thing is you just clamp everything plum before you break out the thin CA and start glueing.

Bob

Zor

Robert,

I edited this post on 06 February 2013 at 07:35 to add a picture worth a thousand words.

I understood that your fuselage was all put together and you were nearly ready to glue when you noticed the aligment problem of the stab versus the main wings.

I suspected that you would use thin CA at all joints so I suggested that you create fillets with good wood glue.
Iwas using Sig-Ment but the LHS does not carry it anymore so I now use TitebondIII .

Fillets can increase the binding area up to five times and make a much stronger joint.

It is not a thicker layer of glue. It is a fillet forming a radius at the joints just like we make fairings where the wings meet the fuselage.

Zor

mattnew

My Feedback: (2)

if the warp is small enough that you can flatten it out with your hands on a bench... I wouldn't worry about it until covering. One thing we've always done, especially when I was young and became a pro at building warped wings ( kidding..  ) was to use the covering shrinking to remove the warp. apply the covering to the wing and seal it down, physically put a slight twist in the wing to straighten using your hands, heat with heat gun to shrink the covering tight and poof, warp is gone.

sensei

That is an awful lot of glue per joint.

Bob

Zor

Hi Bob,

In an 11 lbs biplane of 57 inches wingspan I have less than 3 ounces by weight of glue.
All glued as illustrated. When landing at flying speed in the trees having run out of fuel the model was back in the air inabout 15 minutes (10 minutes to walk to and from the trees and 5 minutes to refuel).

The weight of the glue was figured quite accurately having used 3 1/2 tubes of Sig-Ment glue. Weighting a full new tube and then an empty one and figuring about half of the fresh glue weight disapper while curing.

If anyone wishes or likes to claim it was more like 6 or 7 ounces, which it was not, it would still be worth the absence of damage in a tree landing. That model is also covered with light but strong fabric and finished with genuine aircraft dope which makes it very strong.

Just FYI,

Zor

sensei

You must be talking about your Skybolt. I also add CA fillets to all joint, but I do consider weight on everyone of my builds. I build to fly, not crash and I wouldn't recommend anyone to build to crash, but thats just me. Anyway here is a picture of my typical glue joint including CA fillets.

Bob

Zor

Bob,

Perhaps I could have saved something like 1 1/2 ounces of weight using CA but there would be no discernable difference in the flying characteristics worth talking about but the joints would have been much weaker.
Of course even that can be questioned.

I am hoping that the readers do not conclude from your post that I build to crash nor suggest that they should.
I build to fly but also to reduce the damages and repair work in the advent of an abnormal landing.
I post what I do and give the reasons. I do not crticize whatever anyone else prefers to do. Many simply copy others without knowing why it was done that certain way.

When CA came on the market I tried it and made many tests. I decided it was not for me. I have some but use it only for tacking when clamping is not preactical.

I like to see a joint where I can see the extended binding area. Like many say "it's just me".

Thanks for your picture. It appears ready to be sanded to an aerodynamic rib profile.
The camera angle does not seem to favor seeing the fillets.

Best regards from Zor

sensei

Bob,

Perhaps I could have saved something like 1 1/2 ounces of weight using CA but there would be no discernable difference in the flying characteristics worth talking about but the joints would have been much weaker.
Of course even that can be questioned.

I am hoping that the readers do not conclude from your post that I build to crash nor suggest that they should.
I build to fly but also to reduce the damages and repair work in the advent of an abnormal landing.
I post what I do and give the reasons. I do not crticize whatever anyone else prefers to do. Many simply copy others without knowing why it was done that certain way.

When CA came on the market I tried it and made many tests. I decided it was not for me. I have some but use it only for tacking when clamping is not preactical.

I like to see a joint where I can see the extended binding area. Like many say ''it's just me''.

Thanks for your picture. It appears ready to be sanded to an aerodynamic rib profile.
The camera angle does not seem to favor seeing the fillets.

Best regards from Zor


Your right, 1 1/2 ozs. would not make any difference by itself, but like I said, I consider weight throughout my builds and all those 1 1/2 oz. savings from every area of the airframe add up to several pounds in all cases to date. That does effect the overall flight characteristic dramatically. In the picture I posted you are looking at the tail feathers of a 35% Laser 200. The full scale Laser 200 does not have airfoil tail feathers. Anyway, it's all good...

Bob

Zor

I would have a hard time finding 21 locations where I could save 1.5 ounces of weight or some equivalent to that couple or more pounds. .

Zor



[/quote]

sensei

LOL... Honestly speaking Zor, you will most likely never find a way to save that kind of weight in one of your builds because you don't really believe in the concept as illustrated in the tone of your last couple of posts on the subject. Besides, it takes a great deal more effort to design, and build true hyper light performance airframes. Anyway we are way off the topic of warped wings...

Bob

Zor

Bob,

Coming back to the subject of twist and wing warping I did not experience the problem over dozens of build over the years. Here are details of one of the experiments I did with CA glue that contributed to my decision not to build a complete airframe with CA.

Unfortunately in those days I did not have a camera to have pictures I could post but I think the description will be sufficient.

I took two pieces of 1/8" x 1/8" x 12" long of semi hard balsa and put them on the workbench 2" apart and parallel.

Again with 1/8" x 1/8" I cut 7 pieces 2" long and place them at 90 degrees between the long pieces spacing them every 2". I glued them with thin CA and let them overnight. The next day I put a heavy weight on one end and let about 10 inches sticking out of the workbench surface. I sort of felt the resistance to twisting at the other end. Ya ___not very scientific but some feeling of how much resistance to twist without breaking the structure.

Later during the day I used Sig-Ment glue and made fillets approximating 1/8" inch away from the corners thus increasing the binding area of each join by about 5times. I let that cure overnight. The next day the same twisting feeling was definitely detectable needing considerably more force to produce the same amount of twist.

A similar experiment using 1/8" x 1/8" spruce. 4 pieces of 1/8" x 1/8" 2" long glued at 90 degrees to a long piece of 1/8" x 1/8" spruce about 6 inches long. Two of the 2" pieces glued with CA and no fillet. The two other pieces glued with Sig-Ment and using fillet. I wanted to see what happened when twisting the 2" long pieces. You see now why this experiment was made with spruce instead of balsa. Just grabbing the 2" long piecesand only twisting (rotating; not forcing to change the 90 degree angles) I was able to break the two joins that were only CAed. I was not able to break the two joins that were Sig-Mented and had fillets.

These types of experiments andotherspretty well established my gluing method.
The extra strenght of the joins is well worth what I consider a negligeable added weight as a small portion of the overall weight of a model.

I believe that every well glued join contribute to the overall rigidity and the absence of twist or warp after the structure is taken off the flat work bench.

Note that I am not telling anyone what to do; I am only telling what I do. It is up to the builder to do his build the way that makes him comfortable.

Zor

sensei

Zor,

The two examples of bond lines you just explained along with the method of testing you performed are not valid tests at all for the most part, your tests were more of a torsional rigidity test of an engineered substrate material, and the twisting feeling of your calibrated finger tips. The fact is unless you measured the highest torsional load of those substrates prior to a catastrophic bond line failure then your testing results of adhesive types were then, and are now still meaningless and completely invalid because you still do not possess useable data on a given failure point of those adhesives and bond lines. If any of your other testing was executed in this same manner then I am sure those results are inconclusive as well.

Bob

Zor

Bob,

Knowing some of your background and experience I see that you are looking at a purely engineering and scientific manner.

Using expressions like

- - your calibrated finger tips
- - unless you measured the highest torsional load
- - your testing results of adhesive types were then, and are now still meaningless and completely invalid
- - you still do not possess useable data on a given failure point of those adhesives and bond lines
- - If any of your other testing was executed in this same manner then I am sure those results are inconclusive as well

Agreed with everything you wrote Bob but you are missing the purpose of my tests.
I was aiming at getting some idea as to which glue and gluing method would better resist twisting and warping once taken off the build surface. Also how the gluing method would resist twisting and warping once exposed to the aerodynamic forces in flight.

While you say that my tests were "inconclusive" I again agree with you on a scientific point of view but they were conclusive enough for me to decide to avoid building a whole model with CA type glue and the absence of fillets.

In the pioneering days of radio control when we were building our own radio gear and experimenting with radio control, crashing was a common occurrence and we were trying to find methods of minimizing the damages.

Thus fabric and dope for a strong covering difficult to tear. Another way was to use solid wood (pine or spruce) engine mounts going all the way and sometime passed the trailing edge of the wings. They would also serve as servo mounts.

i cannot write this without remembering "The Good Old Times" of genuine model building as a hobby.
Fortunately there is still a few doing beautiful work with modern materials and facilities.

Best regards Bob.

Zor

sensei

I did not miss the point, the test you performed simply gave you nothing to make a sound decision from because all you really did was test the rigidity of the wood, not the adhesive.
I remember those pioneer days as well because I was right there building my Heathkit AM radio and crashing planes to the key up of those old CB radio guys. I still prefer fabric and dope over plastic film covering on scale stuff, but if I am going kit build or scratch build a hyper light high performance airframe then I am going to cover in plastic film, because the weight penalty is just to high.

What would you say if I told you that your biplane at 57" span could be built ready to fly at 7-8 lbs. instead of 11 lbs. It's doable you know, I have been doing this type of building for many years now and the flight performance would be unbelievable to you at around 7.5 lbs...

Bob

Zor

Bob,

I now feel your dedication and determination.
Of course you are correct all the way.

I never used commercial equipment in those days such as Heatkit rigs.
My radios were original home made stuff.
My original reed relay was made of worn out Gillete razor blades.

What I would say ?
I would say that I would really like to see the structure of one of these biplanes weighting 7.5 lbs.
To my knowledge all that built the Great Planes kit ended up around 10 to 12 lbs.
One fellow recently reported 13 lbs and 2 ounces.

I would also like to see some of your constructions along the mehods that results as you are describing.
Like I recently read about loosing a couple of pounds by loosing 1.5 ounces at many places in the build.
Like 21 places ( 1.5 x 21 = 31.5 ounces or about 2 lbs).

I am hoping that our discussion will terminate soon as we are too far apart to ever be in agreement.
Since I do not know anything (my conclusion from your postings) and never didI can only conclude to wish you all the best and hoping to read and see pictures about your successes with lighteningstrongly builtmodels for minimum damage in crashes.

Enjoy and please forget any of my descriptions of experimental work which was all wrong and useless.

Zor

sensei

Zor wrote:

I would say that I would really like to see the structure of one of these biplanes weighting 7.5 lbs.
To my knowledge all that built the Great Planes kit ended up around 10 to 12 lbs.
One fellow recently reported 13 lbs and 2 ounces.

I am sure they did end up at 10-12 lbs. Just follow the plans and get what you get. I also read about that 13 lb. 2oz. Skybolt in the other forum, all I can say is WOW. Here is a picture of my Lanier 1/3 scale Laser 200 with a 96" span and a DA 50cc power plant, the all up weight is only 15. 5 lbs. That is only 2 lbs. 6 ozs. heavier than this tiny biplane...


Zor wrote:

I would also like to see some of your constructions along the methods that results as you are describing.
Like I recently read about loosing a couple of pounds by loosing 1.5 ounces at many places in the build.
Like 21 places ( 1.5 x 21 = 31.5 ounces or about 2 lbs).

Here are a couple links for you to see the type of construction I am talking about. The key thing to remember is in all my builds, I strive to get a 30% + weight reduction under the norm, and it doesn't matter how small or large the airframe is, percentages are just that. In the first link the average normal weight of all those 40% kits was between 40-45 lbs. This one came in at 28 lbs.

http://www.rcuniverse.com/forum/m_5153525/tm.htm

http://www.***********.com/forums/sh...ad.php?t=56454

http://www.***********.com/forums/sh...ad.php?t=45553

http://www.***********.com/forums/sh...ad.php?t=36868

http://www.***********.com/forums/sh...ad.php?t=14269

Zor

sensei,

I see that you have not been able to show how to reduce the weight of a 10 to 12 lbs model down to about 7.5 lbs. Of course there would be some way at the cost of considerably weaker structure and in the event of a crash we would have a "write off" instead of minimum repairs.

Your postings as examples of your work are admirable but out of proportions.
We can hardly compare an elephant to a horse weight wise.

An area increase byto thepower of 2 of the linear dimension ratio.
The volume increase to the power of 3.
That makes it a lot easier to reduce weight the larger is the model and of course if we neglect the strength factors.

I can imagine a model built to full size and considerably lighter than the original aiplane but you would not see me sit in it and fly it. LOL

I admire your nice work in the so called "giant models" but I am still puzzled about reducing a 10-12 lbs model to about 7.5 lbs without highly compromising its crash results.

Many thanks for your postings and efforts.

Zor

sensei

Zor,

Personally I think you place way too much emphasis on this whole crash results thing old boy... I read your profile and you state your an expert pilot so what's up with all the crash proofing.

Have you ever heard of an airplane called the Dream Machine, it was designed by the late James Rice, and as I recall it has around a 45" wingspan, and is a low wing sport plane that if built to the plans will come in about 5 pounds + from reports of dozens of folks that built them around Texas. I was asked to build one in my typical manner about 8 years ago for one of the guys in our club, when I was finished building and the airplane was ready to fly, the final weight was about 3 lbs. 4 ozs. So you see Zor, percentages are still percentages, an elephant 40% airplane losing 12-14 pounds or a tiny horse airplane losing 1.75 pounds, it is all doable if you have the know what your doing Zor. Anyway I am happy to say that little airplane is still around as most of my built airplanes still are, but keep in mind; I do not build airplanes to survive crashing into the trees, the ground, the water or anyplace that causes sudden stoppage, the pictures you posted of your airplane that settling into the treetops after allowing it to run out of fuel is one thing, and it faired well and I am truly happy for you but let that same airplane fly directly into a solid object and the results will be much different, heavier hits harder, more energy you know. My preference is still flying a great flying all around airplane with stable slow flight characteristics as well. Remember, even a brick will fly with enough power Zor, but who wants it...[:'(]

Bob

EJWash1

My Feedback: (3)

So what you're saying is that if you crashed, you'd be able to incur a 53% weight increase in the repairs to bring the model up to the weight that the typical builder was realizing. A huge increase in repair weight. Realisticlly, a 53% gain in weight is a LOT of crash repairs. But let's say, for example, you built a 40-ounce motorized glider and it came out at 76-ounces. More than 80% of the designed weight. Crash repairs may push it's weight beyond 100% of it's designed weight. A "glider" no more.

What I come away with is build light, and in the event of a repair, you'll still realize the performance of model that is lighter than the designed weight. Build heavy and in the event of a repair, experience the performance of model far more heavier than the designed weight. No?

sensei

Absolutely, build light to fly, because built heavy or light, sudden stoppage destroys airplanes, I don't care how much glue or lumber you throw inside so you may as well enjoy the performance of a lighter airplane.

Bob

Zor

Bob,

Please note that I am not against your philosophy of building light weight.

A light weight model flies like a light weight model . It has less mass and less inertia to handle the wind and the wind gusts. It also, of oourse, has less strength and less resistance to damage in a crash. It often determines if the crashed model ends up in the garbage or on the repair bench.

A note passing by ___an expert pilot by my definition is a fellow who has a fair knowledge of aerodynamics and enjoy experimenting with his models. It is also to be noted that many full size aiplane crashes are often piloted by long experienced pilots and the crash is not due to his handling of the airplane or of the flight.

I do not endorse the insinuation that if a fellow is an expert pilot he does not need to build his models well glued and finished with strong covering well cemented to the structure (frame).

I do not understand any need by anyone to discredit the way someone else prefers in the construction of his models.

Zor