I seems to me one could make a variable load dynamometer out of a torque converter. My guess is that the internals of a water break and a torque converter look a lot alike. This is purely speculation.  To vary the load on a traditional water break one vary the quantity of fluid in the water break. So vary the quantity of the fluid in the torque converter. Some sort of cooling of the torque convent would be needed (this is where all the engine power goes- Heat) I will consult one of my friends who know a lot a about cars see what he thinks.   

 

Warning: Large Dynos are dangerous when under load due to the danger of water break rupture (high pressure water and steel shrapnel). There should always be a protective barrier between you ad the water break when it is under load.

 

Alex Madsen

 

Well... The RD1-B is at a 2.17:1 gear ratio.. so 2700-3000 rpm would be the high end coming out of the PSRU gearbox. I know that some cars their top gear in the tranny is a 1:1, so 3000 rpm at the engine is transmitted to the wheels.. so i would expect (er.. HOPE) the "drivetrain" to handle it..
 
After looking at the PL plans, it seems feasible to build the dyno he describes, but it would involve mounting the engine to a separate test stand and then putting a prop on it.. I was hoping to figure out some way to not have to put the prop on (or if we did, use a loaner prop) so that we could figure out exactly what our engine was capable of doing, THEN getting the prop matched to the known power available, rather than guessing.
 
I guess it would be possible to rig up an axle brake as a load device and couple that with a PL style dyno (measuring torque with a sidearm).. Wouldnt be able to measure static thrust that way.. but hey.. its not a major factor until the right prop is on there.
 
Dont know if practical or not, but a load cell on a trailer hitch might be able to measure static thrust if the whole thing was trailer mounted. For what its worth I swung by the airport and got the cardboard template for the firewall. I may see how practical this will be to build or not.. If the bennies dont outweigh the cost, it may not be worth it.. but it would be nice to get a good breakin on the engine and test under load without having to do it during the flight test.. Might be able to address cooling issues up front too, and insure that what we have is adequate.
 
Dave

Jack Ford wrote:

How's about adapting a flange-style u-joint to the output of the engine and

running a driveshaft? 'Course the driveshaft might get launched spinning at

9k or so, and so might the truck axle pinion and bearings.

Might be a better arrangement to use a stick-shift transmission (in granny)

between the engine and the truck axle, use the axle for brakes and measure

torque at the engine mount. Same cat.

Jack Ford

----- Original Message ----- 

From: <Lehanover@aol.com>

To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Sent: Saturday, January 22, 2005 11:10 AM

Subject: [FlyRotary] Re: Dynos II (was Re: changed to Octane)

In a message dated 1/22/2005 12:08:34 PM Central Standard Time,

dale.r@cox.net writes:

Build a disc to bolt to the companion flange of a truck differential and

the

flywheel of a rotary.

How about elongating half of the bolt holes in the backing plate, in an

arc

to conform with the bolt circle diameter. Use smaller bolts and drop in a

small

needle bearing around each bolt/stud. Now the backing plate can articulate

a

bit around the centerline of the axle. Mount the transducer to a bracket

welded to the housing, and the other end to the backing plate. Calibrate

the output

with a torque wrench.

There you go. A truck axle dyno.

Don't forget the math to take out the effect of the differential ratio,

lest

you report some giant numbers.

Lynn E. Hanover

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