Front carb RCGF 20cc or other?
04-13-2009, 08:57 PM
#26
RE: Front carb RCGF 20cc or other?
Henry,
I checked the prop again and it is balanced. With increase rpm the engine smooths out. If it was an out of balance prop it would be worst with more rpm wouldn't it? However I measured the prop thickness on one side of the hub and the other and it was .002 or an inch different. Checked the prop blade tip and one is 1/16 inch out (further forward) at tip. I'll run it with another prop and see if that makes a difference.
I checked the prop again and it is balanced. With increase rpm the engine smooths out. If it was an out of balance prop it would be worst with more rpm wouldn't it? However I measured the prop thickness on one side of the hub and the other and it was .002 or an inch different. Checked the prop blade tip and one is 1/16 inch out (further forward) at tip. I'll run it with another prop and see if that makes a difference.
04-13-2009, 09:23 PM
#27
RE: Front carb RCGF 20cc or other?
Henry,
I checked the prop and its not out of balance, but its hub may be off a little bit with one tip running about 1/16 to 1/8" out of true with the others . Also the engine smooths out with increase rpm. If the prop was out of balance it would get worst with increase rpm I think. I'll run it with a different prop and see if that makes any difference.
I'm still thinking about the rear carb version in my Top Flight P-40. It has an OS 120 which is rated at 1.9 hp while the 20cc is rated at 2.2. However the gasser is 4 oz heavier and then you need the ignition battery, another 4 oz or so (put it in the fuslage behind the wing to maintain balance). Plane already weights 11lbs 13oz, I'm not sure if it (or I) can handle any more weight with regard to landings. That would put it a 12.5 lbs. I could carry less fuel with the gasser and that might help a little.
I've ordered a 16-8 prop. I'll let you know how that works.
I checked the prop and its not out of balance, but its hub may be off a little bit with one tip running about 1/16 to 1/8" out of true with the others . Also the engine smooths out with increase rpm. If the prop was out of balance it would get worst with increase rpm I think. I'll run it with a different prop and see if that makes any difference.
I'm still thinking about the rear carb version in my Top Flight P-40. It has an OS 120 which is rated at 1.9 hp while the 20cc is rated at 2.2. However the gasser is 4 oz heavier and then you need the ignition battery, another 4 oz or so (put it in the fuslage behind the wing to maintain balance). Plane already weights 11lbs 13oz, I'm not sure if it (or I) can handle any more weight with regard to landings. That would put it a 12.5 lbs. I could carry less fuel with the gasser and that might help a little.
I've ordered a 16-8 prop. I'll let you know how that works.
05-15-2009, 06:46 PM
#28
RE: Front carb RCGF 20cc or other?
Henry,
I rotated the prop 1/3 and bolted back on and now it idles much smoother. Who knows, maybe some improfection in engine shaft and prop hub, but now they are matched up, so I marked the engine, prop and hub so I can always put them back on the same.
I aquired another RCGF 20cc in a Hanger 9 Hellcat. The engine had never been run. Started ok and broke in with the 20 minute ground run at 2,500 rpm. Then fitted with a Master Airscrew 16-8 prop. Still running a little rich and on a 30-1 fuel mix, it will turn 7,700 rpm and seems to produce plenty of thrust. I need the big prop because of the large cowling.
I rotated the prop 1/3 and bolted back on and now it idles much smoother. Who knows, maybe some improfection in engine shaft and prop hub, but now they are matched up, so I marked the engine, prop and hub so I can always put them back on the same.
I aquired another RCGF 20cc in a Hanger 9 Hellcat. The engine had never been run. Started ok and broke in with the 20 minute ground run at 2,500 rpm. Then fitted with a Master Airscrew 16-8 prop. Still running a little rich and on a 30-1 fuel mix, it will turn 7,700 rpm and seems to produce plenty of thrust. I need the big prop because of the large cowling.
05-15-2009, 06:56 PM
#30
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RE: Front carb RCGF 20cc or other?
Great that your 20cc is running well now!!!
In regards to your Hellcat and 20cc... as soon as you can... add a little more gas to raise the oil/gas ratio slightly....the 20cc will definitely give you more rpm......Once you switch to synthetic, you will get even more rpm coming from the engine.
The prop size is great for the engine. I look forward to your flight report.
Cheers
Henry
In regards to your Hellcat and 20cc... as soon as you can... add a little more gas to raise the oil/gas ratio slightly....the 20cc will definitely give you more rpm......Once you switch to synthetic, you will get even more rpm coming from the engine.
The prop size is great for the engine. I look forward to your flight report.
Cheers
Henry
05-15-2009, 07:12 PM
#31
RE: Front carb RCGF 20cc or other?
Henry,
Here is as picture of the P-36 with the 15-7 three blade prop. The 20cc engine is more than enough power for this plane. Weight is 10 lbs 10oz.
Here is as picture of the P-36 with the 15-7 three blade prop. The 20cc engine is more than enough power for this plane. Weight is 10 lbs 10oz.
05-18-2009, 05:41 PM
#32
RE: Front carb RCGF 20cc or other?
I got to test fly the Hanger 9 Hellcat today. The engine was turning up 7,800 rpm at full throttle with idle in the 1,600-1,700 range. This is still slightly rich and on the 30-1 break in fuel mix and a 16-8 three blade Master Airscrew. Even so this engine has more than enough power for the Hellcat. It has more verticle than I will ever need and can do loops as big as you want. This is my second 20cc RCGF engine and I am happy with both of them. Both using the stock muffler with the pipe cut off just past the cowling. Don't know how they will hold up long term, but for now this engine is a winner.
