flyrotary@lancaironline.net Mailing List Archive

I don't understand the problem. Why do you care what the prop load is? A dyno is used to measure the engine torque at various rpms so a dyno run is typically done by setting WOT (after warmup at idle of course), starting with enough load to hold engine at minimum rpm of interest then gradually reducing load to allow rpm to rise to maximum rpm of interest. The whole run takes only seconds if all is running well.

Your dyno operator will know this (or should).

You can calculate prop torque later by multiplying engine torque times redrige ratio.

Tracy

On Tue, Oct 27, 2009 at 10:43 PM, Greg Ward <gregw@onestopdesign.biz> wrote:

Hey Troops;

Finally in the dyno room building the mount plate to begin testing. Tracy says that the engine should be tested with the prop on, and this is kind of hard in a dyno room. We are mounting the engine without the PSRU, so that we don't tear it up in testing, and instead hooking directly to the shaft which is loaded by means of a water brake. We can put any load on it that we want, problem is, how to calculate that prop load in foot-pounds, at different settings. Talked to Craig Cato, and he is leaving for Europe, so doesn't have time to run the calcs, and I am just a dumb high country nail-banger. Any thoughts?

Greg Ward

Lancair 20B N178RG in progress