Practical Composites: Fiberglass Over Wood

We are putting together some good pieces for everyone see how we are doing it. The big tip that we can tell everyone is hair spray. It is too funny to think of either of us ever sing hairspray. One has been bald for half of his life, and I have never been a big coiffure kind of guy.

The pictures that I am including are of a model that is 57" (143cm) x 6" (15cm)  wide and 4" (10cm) tall.

                       

The glass sued is standard s-glass, 2oz per yd glass from Aircraft Spruce . Our experience shows for fuselages, two plies is more than enough for fuselages. Make sure that your plies are pig enough to cover all of the piece and hang over about an inch (2-3cm). More than that makes it hard to support the piece, the fabric keeps pulling away from the edge  or it gets tangled.

Apply the hairspray liberally to wet the surface of the cloth, then use a foam roller to spread the spray and wet all of the glass. It takes a few minutes to work the whole surface. When it dries, it will feel more like paper than silk.

Having learned the hard way. You can let these dry for 15min or so, until they are not tacky to touch. However, do NOT let them dry for lunch and a trip to the hobby shop. The hair spray dries too much and coats the glass so that the resin does not stick. That is bad, it will just wreck your finish and everything will look all orange peel or like bubble city.

I hope this helps with your projects.

So Much For our Idea

We were thinking that we could roll our Schoolgirl UAVs with some great NEU 1915/1.5Y motors to swing our huge props in a dual-motor configuration. I am sure it would work, but I think we will put it into a pusher configuration.

We kind of knew that the motors were big. I got a pair of these 2.7kW beasts from the guys down at Esprit Model in Palm Bay,FL. They are another great supplier of rc stuff. Esprit Model is good about not advertising that they have hard to find stuff and then them being out of stock. Better to know, than to get an email two weeks later saying that they cleared your payment but that you will not get anything for four weeks.

So I got these beer cans. I mean the motors are as big as beer cans. Not an issue, they look great and have built in fans to help with air flow (heli version). I just think that motors are way too big for our school girls. The kevlar skin that we used is way too dense for the skin application. The carbon fiber equivalent material was great and the other airframe came out pounds lighter. I thought I could pay the piper by just putting down more power. It is not going to work that way. We will have to put it in a pusher configuration.

That is one of the cool things about the school girl. We can run with two under-wing motors, as a puller or a pusher. The changes do not effect the airframe much and really are about moving some power wires in the fuselage. It is really convenient. I hope the balsa kits come out well, it should be a great sport flier.

I almost forgot

Prototype two's wing is now almost complete. It will be mated to the fuselage hopefully tonight. I must have really bollocksed up using the pattern that I made on the first plane. It is a different diameter than the first. The second prototype has a more tear drop shaped fuselage that the first aircraft. I think it will make it easier to shore up the system with stringers than the purely round shape.

Cheap RC and carbon fiber

Ok, this will be quick. Do not buy cheap RC electrical connectors. Get good gold plated, high current connectors for your EDF project. Make sure that you shrink wrap them so that they do not spark across each other. Remember, 6s and 50A is welding current level. Just be careful, better to fly next month than to miss it because you grounded out your ESC and motor.

Also, put paper down where ever you are working with carbon fiber materials. If you cut on them or somehow scratch them, you will get broken fibers and that means that you will have hundreds or thousands of terribly painful little daggers waiting to find your skin. Don't sit on your work area, just let us agree to this. It will teach you not to do it twice. Just say no.