Wren MW54 Turbo Prop Locked Rotor Torque Test

There's no published torque specification for a stalled output shaft for the Wren Turbo Prop, so I had to measure it myself. Managed to see 8lb, 7oz at 12 inches from the center of the shaft. Not bad! This isn't a recommended way of measuring torque simply because there's no cooling air stream to keep gearbox and exhaust stack temperatures under control. There is some discoloring of the stainless that wasn't there previously due to this process.

The EGT was being closely monitored and stayed under the max allowable of 800deg C.

The reason this is "Take 2" is due to the fact the first attempt had no physical backup to hold the 28" prop from wildly spinning if the electronic scale broke free. On the first run I didn't even reach full throttle and the flexing of everything spooked me. Figured it best to play it safe with a solid restraint.

FYI - The onlooker in the background is John Benerio, RC heli expert and writer of the "Hover" section of RCM magazine. Thanks for the help John! :-)

Category:

Science & Technology

Tags:

• turbine
• engine
• power measurement
• horse power
• wren
• model
• jet
• mm54

[krugtech]

First off, where did you find the fool who was willing to let you do that to their turbine? What's the torque going to be like when N2 starts to spin a little? At 6k rpm it should taper off to less than a ftlb. Torque curve like a ski slope, i love it.

[StormyMaxPerry]

@krugtech

HA! You should know :D

[krugtech]

This is obviously fake, How can the innards be spinning and the propeller stopped?

[racketmotorman]

Hi Chris

Torque figure right where it should be for stall, at roughly twice max rpm figure .

Say 4.25 ft lbs at 9,000 rpm = ~7.25 hp .

Long live freepower turbines :-)

Cheers

John

[TheLipRipp3r]

SICK TEST!!!!!! ...and a great excuse to run a turbine, too!! hahaha