phantomuav

Hello community!

As a school project we are building a UAV for a competition.

Now, all UAV computers and stuff are all being custom built by myself and the team so need to talk about that.


What do we need to know when it comes to aircraft design?


The two engines planning on being used are two stroke 50.8cc with 5.8HP. A 23x8 prop is recommended by the shop.

The plane is going to be weighing <150kg at max take off weight at the competition. Preferably would like to take off at 200kg.

At the competition max winds are 15kts.

Proposed materials for manufacture were aluminium frame and a carbon fibre/fibreglass skin.

The design was going to be based on the P-61 twin boom style with area for external mounts for bombs and fuel tanks. this is critical.

The proposed airfoil is the NACA 4415. Lift coefficient of 1.4.


After the competition we are planning on using this with a Thermal imaging camera to Aid local Police forces in search and rescue missions.


What are the mathematical models for simulation etc?


If you require any more info please ask.

Thanks for reading this

warrior10

I don't think that you are going to lift of 200kg with 100cc or do I miss something, take the current large scale planes for a comparason. They use 150cc and can't remember the weights now, but should be around 30kg ???

Thanks

Tommie Prinsloo

phantomuav

so really two of these would be better suited for those needs?

http://rcb.shopnz.biz/catalog/produc...817bbcfec3462a


edit:

or these? http://rcb.shopnz.biz/catalog/produc...817bbcfec3462a

Thanks,

BMatthews

First off this discussion forum will not tolerate any further talk about airborne weapons or possible spy gear. Please limit your discussion to strictly the airframe design or this thread will be deleted.

At your proposed size and weight there's really nothing in the model airplane world to compare to this other than models that currently use these same size engines. Only a very select few have been made with weights of up around 50 to 70 kgs range and those were have been for show use only. The size, weight and power you're considering takes the structure and construction out of the model realm by a long ways as well. You're firmly up into the small aircraft or ultralight size and weight category with the weights that you outlined.

On top of this what you are asking is basically for us to type you out a book on aircraft design. It's pretty obvious that you're starting with zero for a baseline on this. Even your airfoil selection shows that you don't appreciate how the aircraft will be operating in various flight modes. So in addtion you're asking us to type you out a book on aerodynamics as well.

For example you say it'll be operating at a lift coefficient of 1.4. As a general rule aircraft, and models, only ever see their maximum lift coefficient when performing the final flare for landing or if they are deliberately being held just shy of the wing's stall point. The rest of the time they operate at a much lower lift coefficient that also brings with it a much lower drag coefficient so that the craft can cruise with acceptable fuel consumption consistent with a speed that meets the specifications. So right there you need to go back and re-evaluate what the size of your wing and airfoil selection would be based on some realistic estimates of target speed range and wing size that results in lift coefficients that are reasonable and then shop for an airfoil that has a low drag coefficient at the target cruise speed. By snatching onto an airfoil first before anything else you put the cart before the horse.

Order of work should be to
A) realistically estimate the size and max gross weight of the craft. Along with that set some realistic target cruise and stall speeds for performance.
B) Figure out a wing area that produces a moderately low Cl for the target cruise speed. Generally this would be in the .15 to .4 range.
C) From sources more in line with ultralight and full size aircraft pick the sort of power you need to lift the max weight at an acceptable climb rate. Yes, the engine power combined with a suitably efficient prop needs to have enough power to lift the weight of the craft. Model comparisons will let you down there since most modelers desire climb rates well above what is expected and tolerated in full size aircraft.
D) Design the structure to meet or come out lighter than the target weight while being strong enough to withstand the target G loads during flight. To allow for unforeseen circumstances this should likely be in the +5, -2 G range.

Rick.

Jeeez - i'd love to have gone to his school - my old school wouldn't supply free pencils let alone a couple of grand for a student project!  Assuming of course he's on the level here and not just rtying to impress Sir to get that A+ for effort................

ohiowoodsrider250r

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maybe he's just a rich peeping tom lol