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Old 07-04-2017, 09:08 AM
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Saito FG 40 gas engine

It seems that there is very little info about these engines. Horizon says it will swing up to a 21X10 prop. I want to put one in a TF 1/5th P-51. Is there ANYONE who has any experience with this engine?
Thanks in advance,
Bill
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Old 07-04-2017, 01:19 PM
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Bill; the FG-40 does not have the power to fly the P-51 the way a Mustang should be flown. I have the FG-36 which is basically the same as the FG-40 installed in the TF 1/5 P-51 kit built Mustang. I had to fly at full throttle most of the time when doing basic maneuvers loops etc. I finally pulled the FG-36 and installed the DLE 55RA in the Mustang. The Mustang came alive with the 55RA installed, plenty of power but the only down side is the two stroke sound. I installed the FG-36 in the H9 30cc Spitfire, the FG-36 is a perfect match for the lighter weight Spitfire and the 4 stroke sound makes it a perfect match for the Spitfire.


Roger
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Old 07-04-2017, 02:03 PM
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Rodger is correct, they run good but don't have a ton of power. I had the 36 on a H-9 Beaver on floats, it would drop like a rock soon as you pulled it back from full throttle. Then I tried a Moki 50cc single, I think it was actually worse! Ended up with a DA 50 on it, lot better. If you want to use a 4 stroke on that plane, I would suggest a Kolm EZ50, but it's better suited for a 50cc 2 stroker
Tom
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Old 07-04-2017, 04:33 PM
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Bill; the video link below shows a TF 1/5 P-51 with a Saito FG-36 in flight. The TF Mustang with the FG-36 begins at approximately 10.10 minutes into the video.




Roger


Another Beautiful Day - RC Planes on Ice (17 min 27 sec)
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Old 12-09-2017, 05:11 PM
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Sorry to drag up a slightly older thread. I've been researching the Saito FG40 and came across this thread.

Roger the Mustang looked to fly reasonably ok in the FG36. Do you remember what prop it was turning and what RPM? Also how much does the Mustang weigh.

Regards Glenn.
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Old 12-10-2017, 11:39 PM
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Originally Posted by NOI53Y View Post
Sorry to drag up a slightly older thread. I've been researching the Saito FG40 and came across this thread.

Roger the Mustang looked to fly reasonably ok in the FG36. Do you remember what prop it was turning and what RPM? Also how much does the Mustang weigh.

Regards Glenn.
Hello Glen, I had an 18x8 prop installed that turned approximately 7700 RPM at full throttle. The TF kit built Mustang weighed 23.5lbs.

Roger
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Old 12-25-2017, 12:30 PM
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The 4-stroke gas engines have very little power.
If you want 4-stroke sound, you would do better to go with a big Saito, convert it to spark ignition (CH-Ignition) and run methanol based fuel in it. This would be in the "same" power category as the 2-stroke gas engines. With spark ignition, you can run it on 95% methanol and 5% oil. You lose a bit of power taking out the 15% nitromethane, but I think that these would still move more air than a gas 4-strokes.

A 40cc 4-stroke gas engine might fly a light wing loading model (such as the RC-Guys 30cc Pitts) if you can fit it in the cowl.

A weird twist is that multi-cylinder engines pack more cc's into the same cowl area, so you might be able to get more power out of a high end manufacturer like Kolm.

If you look at the power output of the same engine running petrol/gas or methanol, the Saito 33cc radial gas may put out 9 lbs of thrust. But the FA-200 Saito radial on methanol fuel puts out about 14.5 lbs of thrust. Basically, they are the same engine, with a different carb.

It's really PI to say this, but I think that Saito and OS should have made 4-stroke completely air-cooled methanol engines, spark ignition, that would run on 95% methanol and 5% oil. They would have had more power on $6/gallon fuel than the current 4-stroke gas engines.
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Old 12-26-2017, 07:21 AM
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Originally Posted by swuest View Post
If you look at the power output of the same engine running petrol/gas or methanol, the Saito 33cc radial gas may put out 9 lbs of thrust. But the FA-200 Saito radial on methanol fuel puts out about 14.5 lbs of thrust. Basically, they are the same engine, with a different carb.

It's really PI to say this, but I think that Saito and OS should have made 4-stroke completely air-cooled methanol engines, spark ignition, that would run on 95% methanol and 5% oil. They would have had more power on $6/gallon fuel than the current 4-stroke gas engines.
If raw power is what you are after, it is hard to beat methanol w/ nitro. The ~14# thrust number you mention is on 20% nitro. You can add nitro to gas too you know to close that gap (but an already hot engine will run even hotter.)
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Old 12-27-2017, 09:28 PM
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Sorry gents, I didn't realise there was responses because I didn't get any emails (I'm not sure if that happens on this forum).

Anyway thanks for the info.

I'm looking at the FG 40 for a scale civilian plan of similar size and weight to the Mustang. Obviously being civilian it doesn't need to go as hard as the Mustang. I'd be happy if I can run say a 20x10 or 21x8 to about 6500rpm.

Do you think the FG 40 might be able to pull those numbers off on those prop sizes?
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Old 07-17-2019, 10:31 AM
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It’s almost two years later and I wonder if there are more people with more experience with the FG-40 who can share their experience here? I am intrigued by the engine but have reservations about paying twice as much as a DLE-35 for less power. Yet the four stroke sound is so intoxicating! Please share more experiences, folks.
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