i am building a scratch bi plane with 6foot wing spane i am wondering whate engine to put in the plane is there a certan weight that the engines can hadle

A gentleman named George Carney a number of years back came up with a formula for ballparking engine size vs weight. This was well before the urge to overpower everything twice over. It will estimate an engine size that is not too small, nor too large. For a 2 stroke engine multiply the weight of your plane by .07 to get around .070 cubic inches in your case. If using a four stroke, multiply the 2 stroke size engine by 1.5 This again would roughly be a 1.00 in your case. It wouldn't hurt for me to know the design and intended type of flying for the plane and the wing area to get a wing loading figure. Take care and let me know_Bob

Shouldnt that 2 stroke size be .70,not .070?

What is the weight of the Aircraft! What is the intended overall weight of the aircraft with the Engine installed/Radio gear ready to fly. A Hypothesis can be made on any configuration but and educated answer needs more Input : ).

It was early and my math skills were lacking. Indeed it should be .70 and I did ask for the wing area but not the total weight. I'm going home now :stupid:

I am reading the beginners Forum and somebody is building a six foot Biplane and is asking what engine he should use. Should we be telling him? Or should we be pointing him towards a 40 size trainer?

Ed s

a 6ft wingspan bipe with a beginner. That could be a problem. There were some excellent Bipes that were docile years ago, 1 was the ACE 120 Bipe. But I would never expect a beginner to fly it. 6 ft. Curtis Jenny was another sweet flyer but again not a beginners plane. I think it should be put away and a trainer would be more in line.

i do run a tranner it is 4ft wing span with a 3 channel radio i hafe a .42 thunder tiger engine in it i just like building from scratch i dont like kits the bottom wing is 142 the top is 164 the weight with out the engine is 7 pounds

Well with that weight I would estimate a 120 in about any class would work just fine on that aircraft. The RCS 1.4 which is Gas and swings a 16 X 8 at about 9100 would also be a great combo. Your final weight with Servo's and Engine etc will be nearly 10 lbs total. You should have a very nice flying aircraft.

Nitro35,
There are too many variables here. It depends greatly on the design of the plane (what type it is). The Great Planes Giant Aeromaster recommends a 41cc (2.4 ci) gasoline engine. The ones I have seen fly well used a 62cc (Zenoah 3.6ci) engine. I have a 75" Ultimate that requires 100 cc (6 ci) for full unlimited performance.

Is this a lightweight WW1 type or an aerobatic model? In any case I highly DON'T recommend a beginner trying this size of plane! You mention "scratch" building. Is this from your own plans or from another designer?

My recommendation is to skip this until you have learned to fly proficiently and how to build and equip a giant scale plane. There is much to learn with giant scale aside from engine size. Correct servo size / linkages / balance .............

Join IMAA and get their magazine and do a lot of looking and visit some flyins. http://www.fly-imaa.org/

Bill

The idea sounds like fun, but I think you are jumping the gun just a little bit. Your biplane will need to be a 4 channel so I think you should at least get some 4 channel experience on another plane before trying to fly a biplane. Also you should have tail dragger experience. Is the trainer you are flying a tail dragger or a trike plane? Since you have a puter then why not download the free FMS flight sim and try some taildraggers? Pick a Corsair and see how you make out. IF you don't add in full up elevator before hitting the throttle, the plane will immediatly nose over into the ground! The plane flys ok if you can getr it off the ground however. Havew fun, Fast!

where do i download the fms sim

It really depends on your intent to use the airplane as well as the wieght. if it was a scale airplane you could get a way with a 91 four stroke, but for acrabatics proboly a 1.80 four stroke or even a BGX. Depends on wieght.
Seth

Did I see FREE flight Sim
That sounds like it just might fit in my budget.

Where can this be found?

Here you go:

http://cgi.ethz.ch/~mmoeller/fms/index_e.html