Well, its got a 'w' at the end of a few outher random numbers

Those wests sure are powerful!
Apparently you can get 7.5 lbs of static thrust out of the West 36!

Thankyou, I stand corrected. That's one spiffy looking and sounding engine, but all the pics on the web site show it mounted to non-competition scale aircraft. I'd like to see it on an Edge or Extra. Maybe I'll be the first.

Using generic logic, a 4C should be about one third CC's larger than it's two stroke bretheren (ie .60 2C or .90 4C), so This motor would compare to a 140 size 2C like a 3W-140iB2F Let's take a look at the specs

3W-140iB2F

8.39ci/137.6cc
5 cyl
8.58 lbs w/o muffler
13.5 hp


RCS 215

13.1ci/215cc
5 cyl
11 lbs w/collector ring
13.5 hp

I imagine with a canister muffler and headers the 3W would weigh about as much as the RCS but now I have a bad @$$ sounding 4C. Ouch, thats sooo expensive though... Big bite to chew.

Mmm, and I was only going to build a 35% plane not a 40%. More money.

Thanks for bringing to my attention this engine, you may have just cost me thousands of dollars. :drowning:

Oh don't you love this hobby

I hate spending money!!!

I love flying planes!!!

I'm too stupid to use the correct clevis!!!!!!!!

Stupid clevis turns my beautiful plane into two!!!

Now I have to spend more money because I love flying planes!!!

Ironic how we spin round and round like one of my spins!!!!

use what ever stroke the TOC's use u can't go wrong there

Great info guys. I might add that horsepower and torque always cross at the same RPM. Because like someone said it's a mathematical equation that gives the horsepower rating.
later daveo

2S vs 4S for 3D: The real issue with 3D is getting close to a 2:1 thrust to weight ratio and having controllable linear power. As long as you can turn a suitable prop and you have linear throttle response, I really don't see what 2S vs 4S matters.

Real world, small 2S engines like to wrap up to high RPMs, so it is difficult to prop in large diameters. A small 4S on the other had produces more torque at lower RPMs, which is well suited to larger diameter props. For smaller planes, the 4S seem to be well suited to meeting the prop requirements for 3D.

As you get larger (35%/40%), the twin 2S engines produce better low end torque not to mention they are gobs lighter than a 4S would be at that size. In that range 2S seem to be the best choice.

I'd say the cross over point seems to be about 1 to 1.5 cu inch. 2S in that range start producing better low end torque and rev to lower RPMs like their 4S counter parts.

monkeyboy you hit the Nail on the Head

The Flip is a bit on the heavy side so it will need some power. What you do not want is heavy power because then you will need tail weight in order to enjoy the airplane's full potential, and then you need a little more power and a little more tail weight...soon you wind up with a DA100 on the nose and a brick on the tail :-) !!!

The YS63 with its little cannister muffler is just about the same weight as the OS50SX with its larger aluminum muffer, but the YS is considerably stronger. I have flown both. The OS spins the 12.25x3.75 at about 12,800 on 20% nitro. The YS will happily turn the 13-4W at about 11,800 on 30% nitro. On 20%, about 11,400. THe OS50SX would quickly overheat, bogged down in the 10's trying to turn the 13x4.

The OS50SX is GREAT for an airplane in the 4.5 to just under 5 pound range when talking serious funfly 3D. The YS will handle about 6 pounds before it becomes hardpressed to shine on vertical pull from a hover.

Mark