Dave Fasken

Hi Fethy; Just to let you know I have made some progress and got the system running  last night with what seems to be reasonable numbers. I still have not come up with a brake yet but plan to make up a small pony brake where I can apply load for a short while and take readings at various loads. The big concern right now is to come up with some kind of universal coupling so that I can hook up different size motors to the brake without any vibration at high RPM's. I may have to make different size brakes as the small 22mm motors may well have difficulty running a large flywheel or at least would require assistance on startup to avoid ESC commutation problems. I already have two different thrust scales that I use as well. One is a conventional L arm using my Medusa scale and works very well for small motors but I wouldnt trust it for larger 30 and 40mm motors. I made up a sliding type scale which uses a plate which slides on bearings bewteen two steel rods.  Seems to work OK with 40 mm motors but due to the close proximity of the propellor to the frame there may well be some interference due to windage. You are probably wondering why I want to make a dynamometer? Well I don't really have a good answer other than I like the challenge and want to be able to say that I made one. I will definitely make some comparisons with different motors but don't  plan to make a career of it. You can tell I am retired and looking for something to do and keep my mind active. I will gladly send you some pictures when I get the unit closer to completion.  Dave

Very interested in your torque reaction method of measuring motor horsepower. I plan on making one similar to what you have and will use the Medusa power analyzer pro and Medusa scale hooked up to my laptop. I will add the appropriate calculations to give horsepower and efficiency to be displayed on the screen. So far I have mounted a 2.5" by 2.5" by 0.5" aluminum plate to an old crankhousing and will make up an adapter plate that will accept all sizes from 22mm up to 50mm.I will make sure that the reaction arm is on the centerline of the crankshaft so as to minimize any angular errors. Before I go any further do you know of any small electric brake that could be added to this unit rather than using the prop to develop load. It would be really neat and also be considerable safer than having a large prop spinning close to you especially when you get up to the larger 40mm size motors. Any input/ideas would be greatly appreciated. Dave Fasken