Wing loading and take off problems
 

Hi guys,
I have built a DUMAS PRODUCTS balsa PZL P11c plane
,a highwing figher from WW2. It has a 30" wingspan and 144 sq.in wing area and empty weights 8 oz.
I put in 400 Graupner 6V, MP 3:1 gearbox and 9x6 APC composite prop, Jeti 110 controller, Micro 555 receiver, 720 Nimh 8 cell pack and 2 Hitec HS81 servos. Fully loaded I think 18 oz. My problems began trying a regular ground take off. It speeds up and doesn't even lift it's tail off. I tried a 4:1 gearbox and 8x6 prop with same results. I am reluctant to attempt a hand launch at this time. Is my wing loading too high or there is not enough power generated by the Graupner motor?
Thanks,
Peter P11c :confused:

Wing loading and take off problems
 

Peter,

Sounds to me like you need the ability to generate more air/ground speed. i.e. higher gearbox ratio and a smaller diameter prop. I encountered the same problem with the GWS P51 when trying to fly at 7000+ elevation. I ended up gearing at 4.4:1 with a 9-7 prop instead of the recommended 5.33:1 with the 10-8 prop. Keep in mind, a larger prop with a low gear ratio generates a high static thrust but it does not mean it will move through the air very fast. I smaller prop turning faster may generate the air speed you need to ROG. A higher airspeed is how real aircraft overcome a high wing loading.

Good luck!
Prop Wrench

Also, If the model weighs only 8oz, you may consider a Speed 300 with about a 3.7:1 ratio. They will almost perform with a 400 but are significantly lighter.

Wing loading and take off problems
 

A friend has a Reno P51 and same thing so he went to
Li-poly's But I worked it out with www.motocalc.com on those
short wing gatta get more airspeed. CU

Wing loading
 

Thanks, I got a copy of motocalc and after running
some numbers I realized that my wing area is too small to support the weight of the plane. So I decided to redo the wing and increase it's area to 220 sq.in. Thus the plane will be able to take off the ground and do some loops. Well, I keep you guys posted nad again appreciate your comments.
Peter
:D

Wing loading and take off problems
 

Peter the email addressis still e-bird
But you can't put a 400 in it and still
get how about Li-poly up under batterys.
CU