Please help me choose and Aerofoil

[Lewist]

Hi

I am building a jet, and i need an aerofoil that gives both good lift without too much drag. It going to have a fairly high wing loading (carrying lots of electronics onboard) so i will need to consider some washout of some sort.

Its also going to be fairly small, about a 30 inch wing span (max!), powered by two edf 40s running fiago 5800 kv motors. and its going to weigh in at about 400 - 500 grams!

also anyone who has the above motor and fan combo.. could you sort me out some specs.. i.e. wieght ot motor and fan, esc and how much current at 3s it draws! and also best case static thrust!

thanks

Lewis

[Arvid K. Gromhol]

If you have a high wing loading, it is my recommendation to use a thick good airfoil, like for instance ClarkY 15% thickness, or similar NACA profile. High aspect ratio,
say 6-7, and a tapered wing, say tip cord/root cord = 0,5.
A 2-3 degree washout may be wise

[Lewist]

ok great..

thanks for the advise!

[BMatthews]

If it has a 30 inch span but wide chord then you're not actually in the heavy category. 400 to 500 gms for a fully ready to fly weight is actually very light.

To enhance the speed I'd suggest a modern thin glider airfoil such as an MH33 or similar. But in truth at that weight you could get away with a relatively thin symetrical section so it'll fly inverted with less issues.

If you have Profili look up the MH33 and the HD45 to 47 airfoils that were intended for Speed 400 pylon racing. Low drag but decent enough lift in the positive direction.

[HELModels]

That is a nice program - get the stand alone application.

[Lewist]

Ok I am really being thick here.

Regardless of how it sounds its going to be heavy!

I have also changed my mind, i am now running 70 mm fans, with a AUW of arround 1kg. if you go to the EDF sections and look for my post - My attempt at edf vtol you will see what i am creating. I have a few ideas about aerofoils myself and so far both of the above have contradicted each other and are not really what i was thinking.. let me go and try the above program and see what i can get out of it.

[BMatthews]

At one Kg that changes things a lot. A 30 inch span model at that weight is going to glide like a greased manhole cover. You need to find a happy middle ground by either adding some wing area (although you didn't say how much you have so far) or make the model lighter.