Engine basics > Four strokes only
Saito FA-82B ???
realSteveSmith:
Has this engine seen any use/success in competitive CL Stunt? I've read good things about the FA-72, but those aren't around and there is no parts support. I've read things suggesting that the FA-82A was known for higher vibration but the 'B' model was a supposed improvement. I couldn't find confirmation of that, however.
Someone fill me in. Is the FA-82B worth buying or must I hold out for a used or NOS FA-72 (and deal with the lack of parts support) if I want to try the 4-stroke thing?
Dennis Toth:
Well, stunt engines, particularly 4strokes, are all about weight. If the 82 is heavier than the 72 you might hold out for the 72. If it is a bored out 72 it could be lighter than it would be worth it.
Here is a Saito chart (https://saito-engines.info/specifications.html) giving weights, looks like the 82(A), is lighter than the 72. On other sites the 82B was within 1/8oz of the 72. Remember we only need about 1/2HP for a full size stunter to perform, the 56 gives 0.9HP. The FS are run pretty much just below peak, more or less one rpm (very close to electrics). The Europeans have been using the FS with higher pitch props then we normally do with wide blades and a rpm down were the old ST60 would run.
Best, DennisT
Brett Buck:
--- Quote from: Dennis Toth on July 28, 2023, 03:23:42 PM ---Well, stunt engines, particularly 4strokes, are all about weight. If the 82 is heavier than the 72 you might hold out for the 72. If it is a bored out 72 it could be lighter than it would be worth it.
--- End quote ---
Vibration is an absolute killer in these giant 4-strokes, even the 72 is pretty notorious for shaking stunt planes to bits.
Brett
realSteveSmith:
--- Quote from: Brett Buck on July 31, 2023, 09:02:30 PM --- Vibration is an absolute killer in these giant 4-strokes, even the 72 is pretty notorious for shaking stunt planes to bits.
Brett
--- End quote ---
OK....I didn't realize the 72 was also considered a shaker. Thanks for pointing that out. That being said, can you think of any reason why a single cylinder 72 4 stroke would vibrate more than a single cylinder 75 (PA for example) 2 stroke?
Or... is less a matter of vibration (from imbalance) and more a matter of less frequent, but more aggressive power pulses for the 4 stroke, vs more frequent but less harsh power pulses for the 2 stroke?
-SS
Robert Zambelli:
TOTAL 100% BULLSH!T.
That probably only happens to people who don’t know how to build a model airplane.
You don’t have a clue what you’re talking about.
I’m really sick and tired of all these people bad mouthing 4 stroke engines, most of whom have ZERO experience with them.
I’ve had experience with just about every 4 stroke engine up to and including the ENYA 90 and NEVER had a plane “shaken to bits”
As I recall, you made similar statements about the Fox 35.
--- Quote from: Brett Buck on July 31, 2023, 09:02:30 PM ---# Vibration is an absolute killer in these giant 4-strokes, even the 72 is pretty notorious for shaking stunt planes to bits.
Brett
--- End quote ---
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