Why do combat r/c airplanes have such a long wing and use only .15 -20 glo motors?

Long wings catch streamer more easily. The power is a class thing, .051 for 1/2A, 15 size for A class, 30 limit for B, 46 for C.

Thanks, because tower sells a p51 and a 109 recomended for 15 motors and yet have a looooong 60 inch wing ,another question do the wing leading edges cut the streamers, I thought a prop would cut them better?

Every surface of the airframe can cut a streamer, not just the prop. In r/c combat, you will get many, many more streamer cuts with parts of the airframe than with the prop. The P-51 and ME-109 you speak of are from Lanier. These two kits are designed for SSC, "Slow, Surviveable Combat", and have the long wings not only to catch more streames but to fly better on little .15's.

THANKS glowplugboy I noticed in the electric club near me, they use ordinary vcr tape for a streamer. isnt that to strong to be useing for a streamer ,I cant see a [:-]wing edge cutting through vcr tape,what do you think.

Wow! VCR tape? I could see that being used in U/C Combat, but not r/c combat. We use standard crepe paper streamers in dry conditions and forestry tape in wet conditions. Here is an essential link on r/c combat: [link=http://www.rccombat.com]www.rccombat.com[/link] . This is the R/C Combat Association. There will lots of useful information regarding easy rules and regs, model information, and so on....

Thanks, I liked the video ,and Ill tell the electric guys about the better crepe paper streamers,I know if I ever start doing combat thats what Im useing. Thanks I found a site where you can buy it.

The key to cutting streamers with the wings is the use of sitcky stuff on the wings. The stickem grabs the streamer and causes it to break.

Some clubs doing their own club-rules don't use sticky, and therefore rely on prop cuts or snagging on corners on the airframe to break the streamer.

Even with out wing sticky, for the same wing area, longer wings have an advantage, they turn tighter and loose less speed than a shorter, thicker wing.

And even with the large wings, don't think combat planes are under-powered. SSC planes are the weakest, they can't climb vertically out of sight, but they still have enough power to move around. The Open B planes with a 64-72" wing will accelerate straight up on a .25 easily. The key is that they weigh a max of 3.5lbs.

Good combat planes have very very light wing loadings, well below what you'd see in a typical trainer, for example.