JimLerch
02-18-2008, 02:06 PM
Has anyone built, or ever heard of, an RC Helicopter dynamometer?
Mostly because I like doing crazy projects (see my sig), I'm strongly considering building some type of chassis helicopter dyno. Asides from the "cool factor" of dynoing a heli, I've been wanting to play with building tuned exhaust pipes. I have the metal working tools and a tig welder to build a tuned pipe, but I'd want a method to measure and document the results..
I've dyno'd my homebuilt diesel generator, and I understand the basics behind measuring the power output of a device. An OS 90 motor claims an output of 3.1hp and an OS 50 claims 1.9hp. After mechanical losses thru the gear train, a 2.5 or 3kw electrical generator head driven by the main rotor blade grips should be sufficient for measuring power output.
My current "plan" is
Build a bracket and clamp system to secure the tail boom to my welding table
Secure heli skids (or main frame) to the welding table
Hang the generator head above the heli, add torque arms to the generator head to keep in from spinning while allowing it to move vertically.
Build coupler to connect generator head input shaft to the heli blade grips (allowing blade grips to rotate normally for blade pitch changes)
Electrically connect generator head to variable resistive load (electric kiln)
Record generator head frequency, voltage, and amperage output. Use these values to calculate engine RPM, Horsepower, and torque.While my plan won't result in a calibrated output initially (due to unknown efficiencies in the generator head) it would produce relative measurements. IE, I started at X power output, made changes, and made it worse by Y% :shock:
Any Thoughts???
Mostly because I like doing crazy projects (see my sig), I'm strongly considering building some type of chassis helicopter dyno. Asides from the "cool factor" of dynoing a heli, I've been wanting to play with building tuned exhaust pipes. I have the metal working tools and a tig welder to build a tuned pipe, but I'd want a method to measure and document the results..
I've dyno'd my homebuilt diesel generator, and I understand the basics behind measuring the power output of a device. An OS 90 motor claims an output of 3.1hp and an OS 50 claims 1.9hp. After mechanical losses thru the gear train, a 2.5 or 3kw electrical generator head driven by the main rotor blade grips should be sufficient for measuring power output.
My current "plan" is
Build a bracket and clamp system to secure the tail boom to my welding table
Secure heli skids (or main frame) to the welding table
Hang the generator head above the heli, add torque arms to the generator head to keep in from spinning while allowing it to move vertically.
Build coupler to connect generator head input shaft to the heli blade grips (allowing blade grips to rotate normally for blade pitch changes)
Electrically connect generator head to variable resistive load (electric kiln)
Record generator head frequency, voltage, and amperage output. Use these values to calculate engine RPM, Horsepower, and torque.While my plan won't result in a calibrated output initially (due to unknown efficiencies in the generator head) it would produce relative measurements. IE, I started at X power output, made changes, and made it worse by Y% :shock:
Any Thoughts???