RCGF 100cc Engine - A Customers Experience

Hey All.
Just a brief introduction to this blog entry...

Pat Roy flies for a living. He is very in tune with the 2 Stroke Gas engines. He is also very particular. Last year, he bought one of our earlier generation 100cc engines, and did a personal review on it. The many items that he brought out that needed improvement to the 100cc engine, were in fact being done and for the better part were done.

The factory sent Pat, these parts, and Ralph Cunningham of RC Ignitions, installed the parts. Pat got the engine back, but because of work commitments could not get to the engine or his plane for the next couple of months. Well, judgement day came a few days ago. Below is Pat's blog report on the performance of the engine.

Pat Roy's Report on the RCGF 100cc Engine - First flight

Okay,

I just went out and ran the rear induction 100 twin again. 93 octane pump gas (with the CA ethanol blend of course), 50-1 Redline, 27-10 Menz prop, H-9 tach. The reason for the 93 octane was to help boost the octane level of the little bit of old 87 octane gas that had sat in the can for the past three months. This is the original engine that helped provide data for the improved versions now on the market. You guys are definitely getting your money's worth!!

I'm not going to tell what the tach readings were. Nobody would believe me, but I'm pretty sure I'm going to need a 28" prop! Or a lot better tach. Or both.

I did make a small change in it before mounting since I like to use only one type of ignition instead of a bunch of different ones. I got rid of the 14mm NGK BMR7A's and installed some 10mm reducer inserts so I could use NGK CM-6 plugs. Doing the same for my single cylinder engines as well just to make life a little easier when it comes to parts replacements and interchangability. I removed the RC Exl ignition and used a real life CH Syncrospark ignition with the machined 10mm plug caps. The change raised the height of the plugs inside the cylinder a bit. I don't know if that provided more cylinder volume to admit more of a combustable mix or slightly lowered compression permitting a little more rpm, or both, or what, but it really runs GOOD!

I have another RCGF rear induction 100 coming that incorporates all the latest improvements for comparisons. If it runs as well or better as this one does I'll be in engine heaven

If anyone wants to try the plug change the reducers can be obtained from both CH and RC Ignitions. There's only one place to get a true Syncrospark. CH is still the king of the hill

Ralph C.,

I don't know what all you did to this thing but whatever they were, they worked!

I finally flew my early version RCGF 100 today. It's the one that has been upgraded with some of the mods that went into the new and improved version. Not all, only a few. Here's the skinny.

35% Edge, 24 lbs. 4 oz. dry. Since it was first flights I added 8 ounces of ballast to the nose to be a bit forward on the C/G for stability during the shake down flight. So plane at 24 lbs., 12 ounces. Add in a pound and a half for a full 32 ounce tank of gas to the take off weight. So make it a round number of 26 pounds.

Field elevation roughly 1,200 msl, 75 degrees f, 30-35% humidity. No wind. Same gas and prop as before. Engine not even close to broken in yet with about 60 ounces of gas through it.

Take off was about 15-20 feet with unlimited vertical as near as I could tell. Second take off in about 10' since I wasn't as nervous as the first flight. Smooth running at all rpm ranges. None of that DA blubbering to be found anywhere. Pulling into a hover it didn't seem to require much throttle to keep it there, generally well below 1/2 stick. I don't use a throttle curve. The big surprise was when I goosed the throttle a little bit in the hover. It was like "Lets Go!!" The plane instantly jumped upwards!! Altavillan and RTK may come in to provide some support of that statement. I never had to go to full throttle to have a fast and solid pull out of the hover. Overall it's a very strong little engine that you get to obtain for less money that it would cost you for one of the "majors".

If I had any complaints at all it would be due to needing to do an idle up after the take off. Since it's real low time a low rpm idle is unreliable, causing for engine stoppage if you've been flying around at low throttle positions for awhile. You don't need to be past 1/2 stick to fly a 26 pound, 2,000 sq. inch wing area plane in any attitude. Matter of fact, flying at high rates, 3d deflections, I spent most of the time at 1/3 throttle stick or less with a little bump once in a while to pull through a maneuver. I think that as the engine breaks in a bit more this issue will take care of itself. If it doesn't, so what, I know what she likes to keep going and moving the throttle trim 3 clicks either way to make her happy is not going to be an issue or inconvenience.

Good engine, plenty of power, smooth running, and a low price. And all that with the early version that's not even close to the standards of the new one. I'm quite pleased with the way this has all turned out. Enough so that I have another one coming for my 41% Giles. This one is all the power I ned and more for the 35% Edge