RPM Question???
#1
Thread Starter
RPM Question???
Hi,
When you guys are dialing your engines for a given desired RPM, are you setting it to GROUND RPM? I did that, then installed a telemetry RPM sensor and was pretty alarmed at the readings from the sky. I picked up 1500-2000 RPM in the air. Is this normal for a 60cc engine??
When you guys are dialing your engines for a given desired RPM, are you setting it to GROUND RPM? I did that, then installed a telemetry RPM sensor and was pretty alarmed at the readings from the sky. I picked up 1500-2000 RPM in the air. Is this normal for a 60cc engine??
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#12
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I do not agree with that statement.
All gasoline (hydrocarbon based) engines will maintain the setting throught the flight envelope we use. Our models do not exceed 1000ft +/_ in altitude , there is no reason to leave a Fat or Rich setting on the ground.
Set your engine to turn the desired RPMs on the ground while keeping in mind the MAX RPM from distributor.
Example : XX engines max is 8000RPMs , when setting it up and use whatever prop you want to achieve say 6800 on the ground. Once in the air it will loose some of the dynamic load on the prop with forward momentum and will increase RPMs,
All gasoline (hydrocarbon based) engines will maintain the setting throught the flight envelope we use. Our models do not exceed 1000ft +/_ in altitude , there is no reason to leave a Fat or Rich setting on the ground.
Set your engine to turn the desired RPMs on the ground while keeping in mind the MAX RPM from distributor.
Example : XX engines max is 8000RPMs , when setting it up and use whatever prop you want to achieve say 6800 on the ground. Once in the air it will loose some of the dynamic load on the prop with forward momentum and will increase RPMs,
#13
Thread Starter
Hi,
That makes it a little trickier. Should we assume that the manufacturer is always referring to 'unloaded' RPM as max? If so, how would one know if you weren't using telemetry? I always knew there was a little bit of unloading in the sky, but I'd have never guessed it would be that much. Frankly, it was a little alarming when I saw the telemetry reading. I don't have any reason to doubt the reading, either, because it's matching the on-board tach and a handheld tach for the ground readings.
That makes it a little trickier. Should we assume that the manufacturer is always referring to 'unloaded' RPM as max? If so, how would one know if you weren't using telemetry? I always knew there was a little bit of unloading in the sky, but I'd have never guessed it would be that much. Frankly, it was a little alarming when I saw the telemetry reading. I don't have any reason to doubt the reading, either, because it's matching the on-board tach and a handheld tach for the ground readings.
#14
Do what you like. I've never torched an engine on a lean run in flight. Seen plenty of other that have in my more than 30 yrs of playing with these things.
Can't say I've ever seen an engine go rich in the air. When all is working normal, they only get leaner.
Can't say I've ever seen an engine go rich in the air. When all is working normal, they only get leaner.
#15
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Hi,
That makes it a little trickier. Should we assume that the manufacturer is always referring to 'unloaded' RPM as max? If so, how would one know if you weren't using telemetry? I always knew there was a little bit of unloading in the sky, but I'd have never guessed it would be that much. Frankly, it was a little alarming when I saw the telemetry reading. I don't have any reason to doubt the reading, either, because it's matching the on-board tach and a handheld tach for the ground readings.
That makes it a little trickier. Should we assume that the manufacturer is always referring to 'unloaded' RPM as max? If so, how would one know if you weren't using telemetry? I always knew there was a little bit of unloading in the sky, but I'd have never guessed it would be that much. Frankly, it was a little alarming when I saw the telemetry reading. I don't have any reason to doubt the reading, either, because it's matching the on-board tach and a handheld tach for the ground readings.
The MAX RPM is what is considered a safe number for continuous running at the highest power level on the curve. I have had engines that were taken beyond the safe number a few times weather it be in a dive or underpropped. I have also overpropped engines but that loss of energy has to go somewhere =(heat).
My philosophy is to stay about 12-1500 under the max while being on the ground.
#19
Thread Starter
Hi,
I was with you until 'they only lean out in the air.' When I first started messing with gasoline engines, they'd invariably richen up when I took off, resulting in power loss and emergency landings. My glow engines tended to lean up in flight, but not my sparkies.
Anyway, I'm sure there are a few more guys on here with RPM telemetry?
I was with you until 'they only lean out in the air.' When I first started messing with gasoline engines, they'd invariably richen up when I took off, resulting in power loss and emergency landings. My glow engines tended to lean up in flight, but not my sparkies.
Anyway, I'm sure there are a few more guys on here with RPM telemetry?
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Shaun: I am glad you posted this info. I have a g 62 that I can only turn 6350 on the ground. If it truly unloads that much I feel much better. Plane flies great as is, plenty of power. I am ordering a rpm sensor now.
Jay
Jay