carbon fibre build

This plane build is for a birdman rally and the plane will crash into water on its maiden ( and probably last) flight

I'm starting on building a glider based on swift by aerianne wing design,
i've just got some carbon fibre tow ( 12k) to my surprise the tow is not very strong, you can break the fibres quite easily if you separate a small number of strands, anybody else used carbon fibre tow,is this usual? If it is usual I'm wondering where its strength comes from? Assuming I have bought genuine cf tow, it must be the epoxy that induces strength somehow???
very confused
this will be a very cheap build, so I intend experimenting with the tow in conjuction with probably bamboo skewers and plastic pipe, the plane is intended to crash!!!

........any crazy ideas on how to make a reasonably strong spar using cf tow in conjuction with household or cheap materials welcome.
dimension: wing span max 8metres

if i can make it too withstand a bit over 1g is the goal ( probably over 2g not required)

whatever said:

........any crazy ideas on how to make a reasonably strong spar using cf tow in conjuction with household or cheap materials welcome.
dimension: wing span max 8metres

if i can make it too withstand a bit over 1g is the goal ( probably over 2g not required)

Click to expand...

My first reaction is, DON'T DO IT! Sounds dangerous. Or is this remote control? 1g wing loading? You flying it in a straight line? This is a wing design I understand to need a certain amount of speed, how hard is this thing hitting?

On the subject of strong: You're trying to use COMPOSITE materials to create stronger than they would be alone. The epoxy is most definitely NOT the strong part of it. Depending on the specific dry goods you might get 750,000 lbs. from the reinforcement then only 10,000 from the matrix. But the matrix provides properties that protect the vulnerabilities of the reinforcement. Kevlar is not as strong as carbon fiber but the combination adds strength in dealing with certain types of abuse.

You would need to vacuum bag, aviation is going to require you get all the air holes out of it. A cheap vacuum pump from Harbor Freight will probably work well enough.

I want to tell you about all the help that the Experimental Aircraft Association http://www.eaa.org would just love to provide you, but I'm wondering if they'll like the sound of what you're taking about. It was they that directed me to the school where I learned composites, they probably know where there's a school around you.

One suggestion: Assuming this is an RC plane you wish to crash as part of whatever spectacle, you can fly an EPS foam structure without any composite material on it, assuming it's not heavy. You could put mere 10 ounce (Per square YARD) fiberglas on it with EPOXY (Polyester resin melts EPS) or even spackle the EPS and put polyester resin, you can get a smooth surface, that is strong enough for surfboards. An EPS pilot onboard plane such as the Skypup will have a wood in the spar. http://machnone.com/con3.html Or you can make a solid foam wing. https://www.flyingfoam.com/content/choosing-right-foam

Here's a forum that can discuss the swept wing design with you. http://www.homebuiltairplanes.com/forums/forum.php

Something to consider: This building out of whatever cheap junk you got laying around. No guarantee it'll survive long enough to crash where you want it to.

http://aero.stanford.edu/reports/swiftaiaa004336.pdf

Dauntless said:

whatever said:

........any crazy ideas on how to make a reasonably strong spar using cf tow in conjuction with household or cheap materials welcome.
dimension: wing span max 8metres

if i can make it too withstand a bit over 1g is the goal ( probably over 2g not required)

Click to expand...

My first reaction is, DON'T DO IT! Sounds dangerous. Or is this remote control? 1g wing loading? You flying it in a straight line? This is a wing design I understand to need a certain amount of speed, how hard is this thing hitting?

On the subject of strong: You're trying to use COMPOSITE materials to create stronger than they would be alone. The epoxy is most definitely NOT the strong part of it. Depending on the specific dry goods you might get 750,000 lbs. from the reinforcement then only 10,000 from the matrix. But the matrix provides properties that protect the vulnerabilities of the reinforcement. Kevlar is not as strong as carbon fiber but the combination adds strength in dealing with certain types of abuse.

You would need to vacuum bag, aviation is going to require you get all the air holes out of it. A cheap vacuum pump from Harbor Freight will probably work well enough.

I want to tell you about all the help that the Experimental Aircraft Association http://www.eaa.org would just love to provide you, but I'm wondering if they'll like the sound of what you're taking about. It was they that directed me to the school where I learned composites, they probably know where there's a school around you.

One suggestion: Assuming this is an RC plane you wish to crash as part of whatever spectacle, you can fly an EPS foam structure without any composite material on it, assuming it's not heavy. You could put mere 10 ounce (Per square YARD) fiberglas on it with EPOXY (Polyester resin melts EPS) or even spackle the EPS and put polyester resin, you can get a smooth surface, that is strong enough for surfboards. An EPS pilot onboard plane such as the Skypup will have a wood in the spar. http://machnone.com/con3.html Or you can make a solid foam wing. https://www.flyingfoam.com/content/choosing-right-foam

Here's a forum that can discuss the swept wing design with you. http://www.homebuiltairplanes.com/forums/forum.php

Something to consider: This building out of whatever cheap junk you got laying around. No guarantee it'll survive long enough to crash where you want it to.

http://aero.stanford.edu/reports/swiftaiaa004336.pdf

Click to expand...

i'm thinking he's running off the end of a pier into water 10 metres or so below, or something similar. Red bull do something similar here in the UK every year. :wink:

It's not Flugtag, for one thing there's nothing so solid or elaborate as he's planning. http://redbullflugtagusa.com/

This is a birdman rally. http://www.birdman.org.uk/

delayed response to dauntless and update:
I've done alot of research on this over many years and have begun some making of carbon fibre spar caps from cf tow and epoxy, have also made the wing ribs.
I've had a major design change, after gathering information on the prandtle-plane designs ( mainly from italian research) using that design I can halve the wingspan to 4m from 8m with almost equivalent lift. So I'll still use the arianne swift wing profile and outline ( since I put alot of time and effort into replicating/researching it) but with the prandtle plane biwing design.
The purpose is to enter a birdman type rally.
The birdman rally that was planned for newcastle australia, seems to have been permanently posponed i.e. looks like it wont go ahead, but there are other birdman rallies held in australia.
The swift has a very low take off speed hence the reason for pursuing that design initially.
There are numerous examples of prandtl-plane designs flying as rc planes, also much detailed research has been carried out on it, I have found some pics of a completed full size prandtl-plane ( 2 seater ) build but no videos of it flying as a full scale human carrying version.
Going into a birdman rally would be a good way to test fly ( the prandtl-plane design also is suitable for water landings with some mods)

I would head over to RCgroups.com and look through the composite stuff.

Could I ask if its a budget build, why are you using CF? Fiberglass would suit the requirements its just not as thin therefore light as the CF.

Also if you can get away with 8m as opposed to 4m, I would go the 8m and utilise the extra wing span for as much lift as possible. Perhaps horizontal stabilizers might play a part?

Have a look at a glider wing profile for inspiration.

I'm not sure if your in it to win or just a build to have some fun but, if you want to experiment buy some depron foam from eckersleys (melbourne) or alternative supplier in aust. Start conceptualizing your designs and either build a make shift wind tunnel or buy some RC equipment from hobbyking and see how it flies and what you can to make it better

Whatever, are you still looking to build this? There is one more prize to be won. Instead of just participating in the rally, you can think of doing something more. If you need any kind of assistance, I would be more than happy to. Let me know.

The Prandtl challenge is in the fact that the biplane wings generated less lift from being so close together. The Fokker Triplane is said to have virtually no lift from the middle wing. I'm not aware of there ever being a laminar flow biplane, so I could see how that would work better.

Do you know of a FLYING Prandlt? I had thought it was just theory up until now.

http://www.eaa.org/news/2011/2011-04-29_synergy.asp

http://www.amazon.com/PrandtlPlane-Wing-Structure-Preliminary-analysis/dp/3848440865