Thread Tools
Nov 01, 2012, 09:14 AM
Registered User
Discussion

What happens if you put a .90 2-stroke in a 60 size plane?


I've always wondered when looking at the .60 2-stroke or .91 4-stroke engine requirements on various planes if you could just say "whatever!" and put a .91 2-stroke in it and grunt like Tim Allen. Does anyone do that?
Sign up now
to remove ads between posts
Nov 01, 2012, 09:30 AM
RC Addict
rmsingh's Avatar
Quote:
Originally Posted by Darkenor View Post
I've always wondered when looking at the .60 2-stroke or .91 4-stroke engine requirements on various planes if you could just say "whatever!" and put a .91 2-stroke in it and grunt like Tim Allen. Does anyone do that?
More Power!!
Nov 01, 2012, 10:15 AM
Registered User
Everyone does it. Sometimes I have seen pilots waiting for the tank to run dry because the idle isn't low enough, and more than one wing fold up because of the extra speed/weight.
Nov 01, 2012, 10:19 AM
Registered User
downunder's Avatar
My son ended up swapping out the .40 engine in his Rite Flyer 40 trainer for a 1.08 but had to set it back about 3" to keep the balance correct. It flew beautifully . I might add that airspeed didn't change because he used a prop pitch (6") that didn't allow high airspeed so there was no problem with overstressing the airframe.
Nov 01, 2012, 10:21 AM
Registered User
Quote:
Originally Posted by aspeed View Post
Everyone does it. Sometimes I have seen pilots waiting for the tank to run dry because the idle isn't low enough, and more than one wing fold up because of the extra speed/weight.
Neat!

That shouldn't make me laugh, or smile, but it kind of does. Thanks for the info.
Nov 01, 2012, 10:44 AM
Registered User
Besides the higher idle airspeed, a nose heavy aircraft is harder to flair on landing.
Nov 01, 2012, 10:56 AM
Registered User
earlwb's Avatar
Well you get more power that is for sure.
But you may have to make changes to get the CG to come out OK.
Also propeller clearance can be a issue if the engine needs to turn a large diameter prop, as some planes don't have enough ground clearance.
Some planes could be affected by the additional power and larger prop causing more torque roll to the left too.
Nov 01, 2012, 11:01 AM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
I always try to select an engine that is heavy enough to balance the CG W/O adding ballst in the nose.

That usually means MORE POWER!
Nov 01, 2012, 11:44 AM
team sleprock
whiskykid's Avatar
I can say this! "the 61fx is within a couple oz's of the 91fx" they are physicaly the same size!
Nov 01, 2012, 01:07 PM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
Quote:
Originally Posted by whiskykid View Post
I can say this! "the 61fx is within a couple oz's of the 91fx" they are physicaly the same size!
Then a 180 Saito 4-stoke seems in order!
Nov 01, 2012, 02:36 PM
Registered User
earlwb's Avatar
I should mention that there are practical limits to how large of a engine one can use. The wing loading can go up considerably turning a plane into something more like trying to fly a brick or the Space Shuttle. Having to take off and land with air speeds over 100 mph for a RC model airplane might be more than a flyer might want to do.

But for modern .60 (10cc) engine size planes, usually one can go up to a 1.20 or 20cc engine OK as people have been putting up to 1.20 size four stroke engines in their planes for a long time without much hassle. Thus a .91 size or 15cc size engine is not a problem. But if the .60 size plane is a old design from many years ago before Schnuerle engines became popular, it can be a problem as the early .60 size planes weren't all that big but more like .45 size planes are today.
Nov 01, 2012, 03:13 PM
Registered User
Alorek's Avatar
I sent you a PM.
Nov 01, 2012, 03:47 PM
Registered User
Quote:
Originally Posted by Darkenor View Post
I've always wondered when looking at the .60 2-stroke or .91 4-stroke engine requirements on various planes if you could just say "whatever!" and put a .91 2-stroke in it and grunt like Tim Allen. Does anyone do that?
YES!!!
OS 91FX in the space reserved for a 65AX = Superb fun
Nov 01, 2012, 07:39 PM
Registered User
No probs . Infact this should be regarded as normal practice . Cheers the pope
Nov 01, 2012, 09:07 PM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
Quote:
Originally Posted by earlwb View Post
I should mention that there are practical limits to how large of a engine one can use. The wing loading can go up considerably turning a plane into something more like trying to fly a brick or the Space Shuttle. Having to take off and land with air speeds over 100 mph for a RC model airplane might be more than a flyer might want to do.

My take is that if ballast is eliminated by a larger engine, the net weight of the aircraft is still the same as W/the smaller engine Wballast.

As long as the structural factor of the airframe is not exceeded there is no negative affect.


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question Hypothetical question - what happens if you run an EDF with the duct removed? LMF5000 Power Systems 9 Apr 18, 2014 03:38 PM
Careful! Wanna See What Happens if you burst a LiPo in a RPG ? BigTradioman Auto Gyros 13 May 18, 2012 10:29 AM
Discussion If you had an extra Fox .45, servos, receiver, etc., what would you put them in? NeveSSL Fuel Plane Talk 8 Apr 18, 2012 09:18 PM
Question What is the best budget 2 stroke 60-61 and 90-91 size engine snowwolf Engines 16 Apr 19, 2007 08:59 AM
what if you v tailed an 60 or electron? what would happen? kwhite Dynamic Soaring 1 Mar 01, 2004 11:05 AM