anyone interested in a dyno
- Thread starter Mark
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Chris Wood
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- Joined
- Jan 4, 2002
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MARK
I AM INTERESTED IN HOW YOU ARE GOING TO LOAD DOWN THE MOTOR?? WATER BRAKE, SOME SORT OF AIR BRAKE??
IS THE MOTOR GOING TO PIVOT ON SOME SORT OF SHAFT MOUNTING SYSTEM SO IT TORQUE'S WITH THE TORQUE OF THE MOTOR???
I AM INTERESTED
LET ME KNOW
CHRIS ;D
I AM INTERESTED IN HOW YOU ARE GOING TO LOAD DOWN THE MOTOR?? WATER BRAKE, SOME SORT OF AIR BRAKE??
IS THE MOTOR GOING TO PIVOT ON SOME SORT OF SHAFT MOUNTING SYSTEM SO IT TORQUE'S WITH THE TORQUE OF THE MOTOR???
I AM INTERESTED
LET ME KNOW
CHRIS ;D
L
lohring
Guest
Inertial dynos are becoming common in model boating. See the two sites below for detailed construction information.
Lohring Miller
http://home.sprintmail.com/~mikejhoff/dyno.htm
http://www1.cedar-rapids.net/tdkmotor/INDEX.HTM
Lohring Miller
http://home.sprintmail.com/~mikejhoff/dyno.htm
http://www1.cedar-rapids.net/tdkmotor/INDEX.HTM
I was going to load the unit with a hydraulic pump and a very large oil reserve
I am a little undecided on the inertia dyno setup because it only measures accelaration not constant running at high speed which is what a rigger does. This means it doesn't measure the effects that creep in with rising temperature.
If I am incorrect please let me know.
At the moment I think for model boat racing a steady state dyno would be the best set-up.
Tell me which way you would do it and why considering the conditions we run at.
I am a little undecided on the inertia dyno setup because it only measures accelaration not constant running at high speed which is what a rigger does. This means it doesn't measure the effects that creep in with rising temperature.
If I am incorrect please let me know.
At the moment I think for model boat racing a steady state dyno would be the best set-up.
Tell me which way you would do it and why considering the conditions we run at.
- Joined
- Nov 2, 2002
- Messages
- 2,662
Mark,
You may be correct about temperature problems with inertial dynos. Brian Callahan and Martin Davis on rcboat.com were using them but I think I read a while ago that they found the temperature effects had corrupted their results. Also they have had problems with the sprag clutches and accurately measuring the acceleration (ie a high rate of speed change) is actually quite difficult.
I have recently considered an eddy current brake dyno. The load on the motor can be easily controlled by varying the strength of electromagnetic feilds. I would use several discs, probably aluminium, of a small diameter because of the high rpm involved. I was thinking that the whole eddy current brake could be run immersed in water for heat dissipation, although there would be significant drag from water, so maybe forced air cooling would be better. I was thinking the torque reaction could be measured at the engine, by a lever and spring scale, possibly with a damper.
Coupling a load to the motor has been problematic with some dynos. They have been using flex cables, but when the engine is suddenly slowed the cable is unwound and snaps. Thus on the inertial dynos they have been using sprag clutches. These have trouble with the speeds and loads involved.
I would like to build a dyno, but I have plenty of other projects on the go as well, there are only so many hours in the day! ;D Keep us posted tho.
Ian.
You may be correct about temperature problems with inertial dynos. Brian Callahan and Martin Davis on rcboat.com were using them but I think I read a while ago that they found the temperature effects had corrupted their results. Also they have had problems with the sprag clutches and accurately measuring the acceleration (ie a high rate of speed change) is actually quite difficult.
I have recently considered an eddy current brake dyno. The load on the motor can be easily controlled by varying the strength of electromagnetic feilds. I would use several discs, probably aluminium, of a small diameter because of the high rpm involved. I was thinking that the whole eddy current brake could be run immersed in water for heat dissipation, although there would be significant drag from water, so maybe forced air cooling would be better. I was thinking the torque reaction could be measured at the engine, by a lever and spring scale, possibly with a damper.
Coupling a load to the motor has been problematic with some dynos. They have been using flex cables, but when the engine is suddenly slowed the cable is unwound and snaps. Thus on the inertial dynos they have been using sprag clutches. These have trouble with the speeds and loads involved.
I would like to build a dyno, but I have plenty of other projects on the go as well, there are only so many hours in the day! ;D Keep us posted tho.
Ian.
Mark, I would have to agree the inertia dyno would not give a true representation of what a motor will do in a race. One of the sites listed by Lohring stated that inertia dyno's were ideal for carting as acceleration was more relevant to the application - where as brake type dyno's are more for WOT type runs with little or no fluctuations in throttle position. To me that sounds just like what our motors do during oval racing. As long as you can launch the thing from the shore then peak power at WOT would be what I think would be more desirable.
