Hi all...some beginner questions

[uonuav]

Dear all,

I am developing a low cost UAV. My approach is to start with a model plane and modifying it. However, I have problems with engine and prop selection.

I am pretty new in such things. What I am looking for is to have a duration of around 4 hours, 1000ft alt and the range is to be found after I know which engine to use. I have looked up many and many books and urls on aerodynamics which I found is that I also need to find the thrust. The bit I am not sure about is the engine rpm vs load characteristics.
Also, if the way I am approaching is correct, which is to calculate the thrust, then I can find the range it goes along with my other data like the area etc., right? I think this is more link a 'loop' question than something I can solve straight away, isn't it?

What do you guys normally do to determine which engine and prop to use?
I get so confused with my concept at this moment........ :confused:


Thanks in advance.

Stephen

[uonuav]

P.S. I got kicked out from the model plane-engine section in this forum last night whcih I was so surprised...I hope I am posting in the right place this time...thx

[JettPilot]

Use the Honda 32 CC 4 stroke gas engine. It is a weedwhacker engine that has been converted to RC use. It is very reliable and fuel efficient. You will need a big airframe (maybe 8 Feet wingspan or so...) to haul it, but that is not hard to make.

If you did some streingthening, you might be able to make it fly on this airframe..

http://www.cedarhobbies.net/index.php?id=product_desc&product=22


JettPilot

[clolson]

Where would a person go shopping to find the honda 4 stroke engine? Is there an R/C conversion kit you can buy, or do you have to have a machine shop in your garage?

Curt.