What plane for UAV?

[Joan Carles]

Hi all!
I'm looking for a model plane to develop an UAV project. I think what I need is a simple, cheap, easy to fly but able to carry the extra load and extra battery draw for the electronics (GPS, an IMU, some other chips and circuitry).
I will expose my ideas/ conclusions and will appreciate your comments. So anybody is invited to correct me if I'm wrong.

1) I think large models (above 1m60 span) are good in the sense they are more stable (less affected by gusts), will have space and will carry the load and extra battery.

2) For a long time I didn't consider electric power. I think electrics are heavy loaded with batteries and flights are short. Now I'm considering them, sacrificing flight autonomy, for price, simplicity and other reasons (noise, fuel, risks, etc.)

3) I'm looking for models with a low wing load as I think they will fly slower and it will be easier for the autopilot to control it.

4) Candidates I have in mind are, so far:
----a) UAV predator model, either 63" or 78" version. I'm not very happy about the unusual V-tail and the downwards fin when landing... I think this has space at the mouth and a large wing area.

----b) Transall C-160, 78" converted to electric. I love that flying sausage... but am not sure about the weight change if moved to electric.

----c) Any Cessna, 60-70", electric. Anybody can compare it with C-160 in flight behaviour?

----d) A standard squarish trainer. The cheapest option for the least tears if crashed. Is it advisable?

[John O'Sullivan]

1) Larger is more stable, but requires more a more complex setup. Having flown aerial photography for 5 years, I find a model of 42 to 56" span weighing a total of 35 to 40 oz. optimal.
2) Don't underestimate the power and duration of electrics. My models with 2200 mah 3 cell Lithium polymer cells (battery weight 5.2 ozs) will fly my models for 40 minutes + and if needed 3300 mah batteries will exceed an hour.

3) Go for a high wing trainer type airplane, The more exotic and "cool type" planes can be less stable and when it comes to UAV type missions the "simpler the better" motto is of prime concern. The more you have to concentrate on actual flying, the less time you have to spend on the functionality of the photography etc.

4)A personal quirk, but I feel the Predator is a "cool looking THING" without much to recommend it aerodynamically. UAV " predator types" - Cool looking, but that's all they have going for them.
Any variation from a simple proven high wing monoplane brings in needless complication.
d) Standard Squarish Trainer - now you are talking "practical". You won't go too far wrong with a simple model. Once you have the first or second simple model behind you, feel free to modify and adapt to suit your personal flying style and needs. However in the initial stages keep things as simple as possible.

John O'Sullivan
www.windandwavemodels.com/Eyespy07.html

[Joan Carles]

thanks, John

I'm glad (and surprised shops don't say that) you can fly electric for over 30 min.

Your eyespy are really nice. The electronics I plan are bigger than a camera, go inside and draw more current, but 70 or 80" are therefore too much.

I will consider a 60" trainer converted to electric. Not so impressing to friends as the others, but....

[icebear]

Joan,

I can only agree with John. I have a lot of experience with models in the 40"-60" wingspan range and I actually prefer models around 50" for AP and autonomous missions.
With the current technology you can easily get an hour duration if you dont load the plane with too much gear.
I recently added a 4,2Ah pack to my 55" SuperMiss and that should give me about hours runtime. The current 2,5Ah pack gives me 30 minutes runtime and actually that is sufficient for most "missions" AND that is carrying a 5 oz camera and 2 oz GPS datalogger + the autopilot.
I have also been very happy with my 3,5 lb, 56" NSP Viking which can carries a pound or so of load (total weight 3,5 lb).

/Björn

[Gary Mortimer]

Joan,

Yep all above is good, a friend recently gave me a gas powered monster to fly, I have taken it out once.

The large wing makes transporting it a pain and messy hot engine at the front just a pain.

All the junk associated with getting it started.

No I am more than happy stepping out with my electrified glider.

It would either be a larger glider or out of the box electric trainer for me. A trainer airframe gives stacks of room for stuff. The only downside to a powered glider in my opinion.

Good luck

G

[Joan Carles]

Hello and thanks everybody!!

Basically I'm abandoning the idea of scales and huge...

I'll go for a 60" trainer, converted to electric. I'll have little practical experience in planes and none with electrics.

My idea is to learn how to fly and then fit my electronics. I plan a fairly professional autopilot with a 300 $ or so IMU plus a big chip doing all the tasks.

Eventually I've in mind a system for auto landing maybe based on artificial vision with a separate processor for that. But so far I'm already busy till at least 2010 !!!

Good flights!!

[Gary Mortimer]

I stepped out and broke that glider earlier, ho hum.

Time to build another

[Altocirrus]

If I was developing a UAV and wasn't going to scratch build, I'd probably go for the Multiplex Twin Star II (http://www.multiplexusa.com/models/kits/twin_star_ii.php)

Edit: I didn't notice you'd made a decision, I should have been reading the thread more thoroughly! Sounds like a good choice though (though my suggestion still stands ;) ), good luck the project!

[Gary Mortimer]

The twinstar is a wonderful airframe, probably the best bang for buck I have ever had out of a model.

Especially when you make it brushless.

It also has the advantage of no props infront of forward facing cameras out of the box.

Theres not much space in the airframe unless you butcher it.

Now a twice sized twinstar.....

[sneasle]

Sig Kadet senior would be a great option, along with any of the Telemasters.

[John O'Sullivan]

I got an Electro Telemaster (73") a few months ago and finished it last night. The intention was to expand on the capabilities of my Eyespies. Had its maiden flight this morning and flew like a dream. Weather started out at -6 deg C with clear skies,but warmed up to -2 with less than 8 kph winds - perfect conditions for this time of year.

It is a big but simple plane and will serve me well. However, the first obvious thing about it is the need to pay close attention to equipment and flying procedures. With a smaller model, an odd heavy landing or poor approach can scrape by without damage, but with this beast (5.5 lbs) a heavy landing could put it out of action.
(again - the right model for the job)

To compound the situation further, a local flier had an un-flown Telemaster Senior (8ft.) for sale at give-away price with OS61FX. I could not resist and now a Chinese AXI 4130-12 equivalent motor is winging its way to me to replace the hunk of steel and aluminium. So expands the fleet.

I anticipate 90%+ of my photo requierments can be handled by the Eyespy.

To add further to the confusion, I acquired a Draganfly Quadracopter. One of our guys had a Brushless motor Quadracopter out today and the stability and flight capabilities were awesome. It appears to be the answer for tight access situation photography which would rule out the use of winged airplanes.

Good flying,
John

[ggtronic]

John O'Sullivan : thanks for the Eyespy link, thats a nice functionnal bird :eek: . I also agree with all your detail at post # 2 :p

I need is a simple, cheap, easy to fly but able to carry the extra load and extra battery draw for the electronics
1) will have space and will carry the load and extra battery.
3) I'm looking for models with a low wing load.hello Joan Carles

Longer electric fly time is mostly achieve with better aerodynamic:
an appropriate fuselage that provide good airflow wich
mean more efficiency+run time. A sailplane is perfect for that, but fly faster...
http://www.rcgroups.com/forums/showthread.php?t=944276

i'v built a custom plane to do this exact task with 10oz/sq.ft. including 160g camera in my test. It's ugly,
but do theses job easy, and i also consider it is an
excellent trainer because of its nose and slow flying speed : (carry up to 200g of payload)
http://www.rcgroups.com/forums/showthread.php?t=942611

data showed an average power of ~9 watts to sustain flight....-Carl+MIT KID (http://www.rcgroups.com/forums/showthread.php?t=572000)
I have a eagletree V3 logger on its way to actually measur how
much power i need to fly slow and steady with a Clark Y airfoil :confused:
between 30 and 50W ? will see...

Ounce you have a good fuselage with easy balancing capability
you can make yourself the appropriate wing for the appropriate
speed and wind condition :D (Can fly land and troynh gave me this idea ;) )

My bird also fly smooth...but video showing boaring flight
are not so popular :D ... this one done with 10-15mph gusty wind :
http://www.vimeo.com/2380036
This was not a good day to fly smooth with this type of wing ;) --
at 51sec : the wind push me back 50' (flying backward) with
1/3 throttle, and the big effective thrust actualy help alot to
recover (1:1 AUW thrust ratio)

I didn't find any appropriate RC airplane in the market for
big payload and easy balancing configuration ( the main
purpose was also aerial photography ) that also fly very low speed :confused: . Ounce you`v try a 1:1 power ratio airplane
, you dont go back to under power :D .

Carlo's prize (http://www.rcadvisor.com/blog) get me the inspiration to built kits for sale

I'm actulaly building 4 X 60"wingspan kits with smaller motor to achieve
about 8oz/sq.ft wing loading and still lots of power without payload...
And about 10 oz/sq.ft. with all payload in...
PM me if you want one (will do 5 instead of 4...will paint them gray or sand
to get a nice UAV look, just for fun )

[Gary Mortimer]

Cameras are out of the view of the prop!

I bought a stack of foam yesterday to make something similar to yourself, bet mine will be uglier!

[justind123]

Where did you find a 78" predator model?

[ggtronic]

about predator:
I crashed that version, in part because the V-tail just isn't enough control by itself (http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A787)

3) Go for a high wing trainer type airplane, The more exotic and "cool type" planes can be less stable
4)A personal quirk, but I feel the Predator is a "cool looking THING" without much to recommend it aerodynamically. UAV " predator types" - Cool looking, but that's all they have going for them.

[justind123]

nitroplanes no longer sells the 75" predator model only the 63" which is way to small for my liking.... id like there to be an even bigger one..... anyone have any ideas where to find these... id like to keep it predator looking or sailplane type with a pusher style prop for cheap!!!

[Joan Carles]

Where did you find a 78" predator model?

it's available from www.jcelectronica.com They have a manufacturer. But i'm not sure if they can send to USA :confused:

[ggtronic]

lets put a foot in this new market :confused:

unfortunately, i dont have video with the painted bird...
anybody find something wrong with my listing (http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=110371278464) ?