APIA

Hey All
Is there a chart or something in existence that provides for engine size to airplane weight ratio. I know this is probably based on the static thrust of the engine., but that varies with different prop pitch and diameter.
Thanks
-Tom

FLYBOY

My Feedback: (11)

It varies greatly by model and builder. If you want to get an idea though, go to towerhobbies.com and look at the kits on the site and see the what engines they put on each. You can get an idea that way. Most kits have a range of engines, and most use the biggest engine in the range as a starting point. Many people now use bigger engines than they recommend to do more vertical manuevering. Its not the end all, but it will give you a starting point.

ballgunner

My Feedback: (1)

FlyBoy has it right. There are so many variables that weight alone will not determine engine size. You could put a hemi in a cigar box and it would surely go. Wing area, field altitude etc.. The manufacturer's recommendations are usually on the low side for the smallest engine. Unless itis copletely preposterous go for the largest recommended engine. There is nothing more disturbing than trying to climb over an obstacle than too little power.

Kaos Rulz

Most manufactors provide the engine range to accomodate the smaller engine for ROG from concrete, or asphalt, while the larger engine to ROG from grass. Admittedly, the larger engine flies the plane crisper than the low end of the engine range.

APIA

Thanks for the unput guys

Rcpilot

My Feedback: (78)

Here's my rule of thumb for MINIMUM engine size at 6000' above sea level:

.10 cubic inches for every 1 pound of airplane

So--a 4 pound plane would have a MINIMUM .40 engine

A--10 pound plane would need a MINIMUM 1.00 cubic inch engine

That won't get ya hovering---but it does provide decent performance