Discussion forum for a community-designed UAV airframe
This is a forum to discuss the creation of a community-designed UAV airframe that can be put into production. Once the basic scope and core participants of the projects have been decided on, we can move the project to a Huddle workspace for the actual design, planning and collaboration.
Replies to This Discussion
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ModeratorPermalink Reply by Gary Mortimer on -
Very pretty designs gentlemen, well done.
Caution with the ali mount Michal you might be introducing vibration. Although it does make it easier to get the downthrust right.
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Permalink Reply by Dan on -
Hey every one there seems to be a lot of conflicting missions....
lucky that air frames is one aera that i do know something about... (not as much as some here though!!)
this is what i propose!!
1) PAYLOAD (that is weight that the plane can carry after all the systems are on board INC.batts/Fuel)
I suggest 500g and 45min duration (as sugested earlier)
2) operational weather conditions: I like my aircraft to be able to handle (idealy) at 15 knts cross wind (same as the cross wind rating of a cessna 172R)and mabe a head wind of 20knts.
this obviously means that there needs to be some weight behind this UAV. (i suggest 7-10kg)
3) if this aircraft is to go into production I would suggest Foam construction for two reasons .....
1) lets face it beginers are going to go "wow cool ill get the one with an auto pilot " when they crash its hard for them too replace Carbon fibre (i know its super strong but there are some "special" people out there.
2) Foam is Cheap!!!! and forgiving when landing! also any one with 5 min of research can figure out how to replace broken parts.
4) Full controls !!!! horizontal elevators, vertical stabilizers, aelirons!!! possibly Flaps!!.
5) speed.... i would have thought that if this was to be a camera platform it would be best if it was slow!! more photo oppertunities!! how ever speed is mearly a case of increasing wing area or reducing it for a given weight! > not such a big issue at the momment!.
5) i also propose that electric is the way to go for short term (less than an hour trips)
for the simple reason that there is less Vibration!.......... ALSO PETROL/GAS EATS FOAM!!!! (styrofoam)
so i think that cancels out the chance of a petrol engine.... (also petrol engines are pretty expensive)
6) there was some talk earlier as to weather the Auto pilot will stabilize the camera enough...... or weather the camera should have its on stabilization gear.
I would 100% recommend that both are used. i know from personal experience of flying it doesnt matter how fast you correct for bumps and things like that you are still going to feel it inside the plane...
some thing like gusts, wind shear, thermals, increase decrease in power, xwind or just normal turbulence will all have an effect inside the cabin (you feel them) give you an example...... the air feild that i land at has quite bad sink just before the thresh hold when i was coming in to land the one day, (10kts gusting 17kts direct sidewind) i was just over the thresh hold at about 50 feet when the wind gusted and the wings rolled about twenty degrees it doesnt sound like much but that kind of thing WILL happen at some point to the UAV and if the camera is stabilized and the autopilot is on, the camera will still be able to take top class shots.
I hope i explained that well ;-)
7) wings ..... i would deffinately put the wings on the top of the fuselage as this is the most stable form of wing configuration.
8) were you put the prop ( front or back) doesnt concern me to much as i dont have that much knowlege in this area same goes for tail booms (single or twin) i would go with motor up from and a single boom for no other reson than thats what im used to ;-) (i dont know the pros and cons of these configurations if some one does please enlighten me !!!) ;-)
Finaly here is a Cof G calculator which is obviously important if you intend to add payload ...
it also give the Cof G limits for and aft
http://adamone.rchomepage.com/cg_calc.htm
There that my $0.02 worth of info on How I would do things.
please add me to the huddle group!
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ModeratorPermalink Reply by Morli on -
Hi Dan,
"so i think that cancels out the chance of a petrol engine.... (also petrol engines are pretty expensive)"
they are no longer expensive now, infact they are cheaper now than nitro in most cases and economical in terms of fuel cost/usage too :)). But I agree , Foam models are good for R & D and taking first steps into this hobby. :))
check the prices of nitro versus petrol/gas engine . some gas eng price here & here
"before the thresh hold when i was coming in to land the one day, (10kts gusting 17kts direct sidewind) i was just over the thresh hold at about 50 feet when the wind gusted and the wings rolled about twenty degrees it doesn't sound like much but that kind of thing"
Camera aided and fvp type flying are not expected infact not used for landing /take off, even in professional/mil world they are done in full direct view of controller.
Electric propulsion is good :)) . Silent, no mess, no cleaning, almost no caddy, environment friendly
BTW
Skywalker airframe looks perfect if it lives up to its expectations
Reviews will be coming in soon. Cheers
my 2 cents too
Morli
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Permalink Reply by Krzysztof Bosak on -
By look I can tell Skywalker should be seriously unstable on yaw in sidewinds, and uncomfortable tail MTBF.
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ModeratorPermalink Reply by Morli on -
hi Kriys,
Pls, you know, we/me are Nooobs, what is MTBF & how to fix the issues ,
Tnks
Morli
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Permalink Reply by Krzysztof Bosak on
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just kidding about MTBF
it simply breaks when it is a combination of soft+soft or soft+rigid during landings
we made a very thick one in Pteryx because we had good quality resins.
vtail is not much better there.
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ModeratorPermalink Reply by Gary Mortimer on -
MTBF- Mean time between failure, a phrase you will need to learn Morli, all sorts of forms I have had to fill lately have included it.
Remember endurance wise in the USA proposed rules mean flight times of greater than 30 minutes will require a NOTAM.
EPP foam is great.
As for flaps and full surfaces, its all complexity.
The simplest system is what is needed.
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Permalink Reply by Krzysztof Bosak on
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"The simplest system is what is needed."
Consider: "Things should be made as simple as possible, but not simpler."
I agree vtail is robust, except when you pick just any good looking vtail.
Epp is good but in Ttail as in skywalker, there is thin EPP pipe glued around carbon or plastic pipe. This will break first, and still you don't have enough rudder surface in Skywalker to cure the problem with huge surface of the fuselage AND the problem of turbulent airflow after the partially obscured propeller. -
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ModeratorPermalink Reply by Morli on -
Thanks Gary ,Got it :) , My brain went grazing else were when I asked it :))
I don't intend to fill any form for now , USA rules don't mean much for now either.
EPP foam it will be for now till I get some decent hours build up my log and then will see 7k.g( though I am geared for it now but MP code limit won't allow more than 28 miles which is less than 30 mins flying time in straight line)
No flaps or complex surfaces , life is too short of it , may be some other time :)
@Krzys, thanks for the tip,
we can't have both if we pick off the self product ( you can't ask for mustache & aunt too ;-) it is my turn now so figure this one out) -
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ModeratorPermalink Reply by Gary Mortimer on -
I hear you Chris, it will be interesting to see how the skywalker goes, I shall be following it with interest.
As ever on this sort of build thread, ie not buying one off the shelf, have not nailed downed a design brief.
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Permalink Reply by Sarel P. Wagner on -
Build it out from here as a suggestion:
Generic Mission Definition small Cat II UAV:
Fly a payload of no more than 600grams (1.3lbs) for a duration of 30 minutes and take a video for at least 15 minutes and stills for the duration. Fly in winds up to 12 Knots 15-20kph
Send position and other systems data to ground station in real time.
Rgrds
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Permalink Reply by Sarel P. Wagner on
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Payload:
What is in the payload?
1. Camera (Sony Webbie 100g, Iphone 140g, Canon SD camera A3100 125g)
2. Stabilizing platform & servos 80g
3. Payload extra power source (140g LiPo)
What else?
Rgrds
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