I have looked at some airframes and alsmost none of the ARF kits fits the Drone profile to me.
I have never thought that I would find myself in a situation to construct a custom airframe so I looked around for airframes constructed for UAV's and I found something perfect for the job it can be seen at http://www.uavfactory.com/ made completely from composite I do not know what the cost is but judging from this page http://www.troybuiltmodels.com/category/UAVF/Fixed-Wing-UAV-RPV-UAS.html and the pricing of the little penguin's friends I would say that is far more than the general hobbyist can afford.
So I have never worked with composite but fibreglass is not so hard my question would be what would the" way to go" be to construct such a airframe one idea is to turn the actual fuselage in wood to use as a mould to construct the composite the puzzling part to me is the wing itself how is something like that constructed is the something that keeps it in that form on the inside.
I would aprecciate any advice from anybody who can help.
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Dear Ryan
I am looking to upgrade my skywalker 1900 based UAV to a full carbon model airframe.
Please can you quote me . My e mail address is jm.janulewicz@gmail.com
C.P. Ryan said:
Easy to obtain the Carbon fiber fabric and the appropriate epoxy (do not use polyester resin epoxy). Easy to make flat sheets and tubes of various diameter as I have done already. Cost? CF fabric is about $75 per yard * 50 inches wide. If labour is free, the overall cost is not so bad. If you lack experience making plate or tube, do prototype work with fiberglass.... Practice makes perfect.
http://groups.yahoo.com/group/CompositeRockets/
You can actually build something cheaper then that out of composite materiel with out having to build a plug then a mold then a pree preg fabric and then a conclave forming witch is very expencive and give the best result.
Sculpt your model out of dense Styrofoam it is just essayer to carve, then cover it with epoxy ( one application is good enough ) it will prevent the foam from melting, apply tow to tree coat of building primer and sand smooth, apply releasing agent and then tree good coat of wax, vacuum is the way to go it will prevent extra resin and give the cloth it’s rigidity, build a vacuum pump out of a 12$ bike pump just by reversing the diaphragm and adding a check valve, go to www.solarcomposites.com to bay the vacuum membrane tape baby blanket and vacuum gage, you can also get the fabric there it’s good quality and cheaper , you will have to formed the top and bottom ( or side to side ) separately bay isolating half of you mold for every half but be quick to do it ( you only have a 8 hours windows to formed both half and have to have all your bulkhead reedy to put them together so that the bonding is solid) glue all the bulkhead to the first half and pre soak all your 1” strip pre cut all the access panel to give you room to apply all the strip to joined the tow half together so fab small tools out of dowel and weir to help you reached every corner of it , let cure and sand smooth so you can apply a thin coat of finishing medium ( the choice is up to you)
ET violas 1/3 of the cost and you keep all the property.( this is just for fuselag the wing is a hol other story)
WE ARE A PRECISION COMPOSITE MANUFACTURE IN NW PORTLAND AND CAN BUILD WITH VERY HIGH TOLERANCE AND ACCURACY UAV TYPE AIRFRAMES AND COMPONENTS. SHORT RUN -- HIGH VOLUME. LOW COST MANUFACTURING TECHNIQUES. REASONABLE START-UP COSTS.
C.P. RYAN
My method is by no means cheap... but I'm shooting for much cheaper then the Penguin setup (for a significant jump in size...)
Carbon structured wing (design in progress... no control surfaces integrated yet)
.25" thick ribs (again, BEEFY compared to the Penguin), .5" square spars, 1" hollow tube for wires/fuel
The plan once these are glued up is to then make a 50/50 mix of corn starch and plaster of paris... and to smear it in the void space until I have no open voids. Smooth/shape it using additional mixture and sanding... then lay up pre-preg on top of that. Once the skin has cured I can drill some holes and use ordinary water to wash out my void spaces.
That's just food for though on doing it.
Also... FEA results for those interested. 50lb load applied on the outside edge and safety factor as the measurement... (the significance being that this is a tilt-rotor ;) )
Building your own composite wings is actually very easy and not that expensive. It depends on whether you want them to be exclusively composite or willing to have a balsa/composite hybrid wing. I hope to be doing this exact job very shortly. Stay tuned. It depends on how "perfect" you want to be with your design. If you are looking for a plain profile, straight, constant chord wing then it is very easy indeed. It will require a little trial and error when setting up weight/balance and tail size but don't be put off. This is half the fun. You will be surpised how easily you can achieve a workable result. It won't be the prettiest or most efficient thing in the air, but it will save you thousands compared to buying a commercially available airframe.
A big hint, have a look at commercially available race car aerodynamics books. They have heaps on information on construction of aerodynamic devices and even how to build you own tooling!
I am building an AMR "Payload Master 100" based UAV at the moment which has an 11 foot wingspan but even then I will be struggling to get the endurance I want. Once all the bugs are ironed out I plan to transfer all the gear into a larger, custom low cost composite airframe.
My plan is to do a build log with photos when I get to that stage.
My advice to you is to get stuck in and give it a go!
Okay so I have worked out some more information on the manufacture of a custom airframe, there are some ways but I can have me some fun struggling this through by myself.
I have looked upsome moulding particulars apperently there are 2 methods to do this vacuum bagging and press moulding and quite a few sources suggest that vacuum bagging performs a lot better even on a commercial scale.
A few concerns I have is firstly on the wings the most people I have seen is using ether balsa ribs or a foam core I hate balsa I built the whole titanic kit and I hated it I made it swim (no iceburg required)
So I was thinking the best way to do this is using ribs can ribs be routed out of carbon and when a ribset is constructed how is it covered (some construction photos would be a big help)
As for the fuse I am planning to have it cnc routed out of foam for a plug to construct the moulds.
I know these questions are probably tedious but you are the experienced people ask me about computers and least cost routers and I know carbon composite calls for a expensive airframe.
As I have said before custom airframe is the only way to go for exactly what you want. I posted a similarly disheartened thread about the lack of airframes that fit my circumstances. Around 30 airframes were mentioned by many people and although they are good airframes they are still no where near what I ideally want (or could modify to be that way).
In the UK a company called Carbon Mods does kits to help people build what they want (although to small for a full plane). You can buy the parts individually, so "create" your own kit able to do your plane. More importantly though is you can get flexible sheeting (kevlar, fibreglass, carbon fibre) so reinforcement could be epic. I'm planning a tiny quad to test the materials before I even think of using it in my plane build.
I have just found something more fitting obviously it's way larger that I plan.
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