Materials that don't break all the time

[qk11]

Every time my team members fly their plane, the balsa wood breaks somewhere and has to be glued back together. Are there materials other than balsa that work well for this event and don't break every time?

[coachchuckaahs]

Not really.

Balsa, being a natural element, is variable in nature and you may have some poor parts. However, the EWS planes have a relatively heavy power plant, and in order to make weight you need to build light, moreso than Wright Stuff.

If you have an all-wood kit, these can be a bit more fragile than the carbon kits, but are far cheaper and easier to build. the "carbon" kits use carbon fiber strips and rods for the leaded and trailing edges of the flight surfaces, but all ribs and the motorstick are balsa. The stiffness to weight ratio of balsa is very high.

What parts are mostly breaking?

These are fragile devices, adn handling skills are important. Only one person should touch the plane at any given time. Place it in a stand to hand it off if possible. Walk with the plane in front of you so you can see before it hits anything. Turn very slowly when a plane is in hand. I preach these things constantly, and then it is me that turns too quick and destroys a plane!

If you can post any photos of troublesome areas, perhaps I can give further advice.

If the broken parts are repaired with CA (superglue), that can be brittle and lead to repeated failures. Sometimes you may just need to replace a bad part. Often it is the joints that break rather than the actual wood, usually due to poor joint construction. There must be a full complete physical contact before gluing, or the glue will bridge the joint and become very brittle.

In the grand scheme of things, these are extremely robust indoor planes compared to many other planes that are flown in AMA competition. Even so, learning careful handling is a challenge for midschoolers, especially after several repairs.

Coach Chuck

[cctl29]

We have a question with regard to material breakage - can Mylar covering on the wings be repaired? We just noticed a small hole (about 3mm x 4mm) along the trailing edge. One of the supporting struts came loose and caused the small hole. How should we go about having it repaired? Thanks in advance.

[jander14indoor]

Absolutely you can repair Mylar. Spread out a small patch on a piece of paper, smoothing it out. Should be larger than the hole by 1/4 plus inch. Paper is used to handle the small piece of mylar while keeping it smooth.
Then, take some chapstick or glue stick and rube it lightly around the hole. Don't over do it!
Flip the paper over centering the patch over the hole. Lightly rub it down.

Jeff Anderson
Livonia, MI

[coachchuckaahs]

Jeff:

You make it sound so easy!

The Mylar we use on these planes is fairly thick, and well behaved. Jeff's approach works well.

We often do a slightly more complex route. We use Vaseline (very little) to stick the scrap of covering to paper. Then we trim the paper and covering with sharp scissors, so there is no exposed paper on at least 3 sides. On the 4th side, the "handle", place another scrap of paper over the handle paper, with the covering face up. Now spritz a very light mist of 3M77 above the covering scrap, and let it fall down. It does not need much.

Now remove the extra scrap of paper, and place the patch over the tear. Work it lightly in place, then peal back the paper. If you used very minimal Vaseline, it will peal back easily.

That is what we do. But Jeff's approach is much easier!

In a contest, especially with these heavy planes, we will just use a small piece of scotch tape.

Coach Chuck

[cctl29]

Thank you Jeff and Coach Chuck.

A follow up question - does it make any difference whether we patch it on top or from underneath (if accessible) ?

[coachchuckaahs]

Not really. We have done either, depending on the situation. Sometimes if a tear goes past ribs to to the LE/TE, it is easier to place the patch on top. Otherwise, it may be more aesthetically pleasing to put it on the bottom. I think most often we patch from the top.

Coach Chuck

[qk11]

Here is a photo showing breakage after one flight, but it's broken in multiple places and had to be re-glued:
https://drive.google.com/file/d/1zvKFXP ... sp=sharing

Another question related to this post... do you think this plane is fixable or would it be better to start from scratch?

Thank you.

[coachchuckaahs]

Anything is fixable! We had a student one year drop a notebook into our box with 6 LPP's. WE stayed up to 3am rebuilding them, and flew the next day.

Last year at Nationals (AMA Nats), one SO team brought a P-18 (very similar to this year's SO planes), but no box. A gust of wind absolutely destroyed the plane, they were in tears. We pulled out a flat build board and some CA, and within an hour they were flying!

But, if you have the time, I would probably rebuild the stab from scratch.

If you repair, some helpful hints:

• If the balsa is broken, try not to damage the mating pieces. IF you can piece it together, all the better
• Carefully and lightly drag a Sharpie along the break when it is open. When you piece it together, if it is a good fit, you may not be able to find the break
• Remove the stab form the plane so you can put it on a flat building board (same with wing if it is broken)
• Put down wax paper under the surface to be repaired
• Piece the part together. Then lay it flat (likely upside down) on the build board (wax paper). Lay a straightedge along the LE or TE that you are fixing. Now it is straight in both directions
• Using a capillary applicator, put a drop or two of THIN CA on the break. The thin will soak through and join all those fibers, making it stronger than original
• If there is not a good join, or missing parts, splice in fresh wood using a LONG Diagonal cut to maximize gluing area. Get a perfect joint before adding glue.

Coach Chuck