Old message.

Subject:        Pitch change motor
   Date:        Thu, 01 Oct 1998 13:19:28 -0700

Paul wrote:

I talked to an application engineer at Globe and
he recommended this motor. No.. I did not tell him
it was for an airplane. It is an IM-15 type. 12 Volts.
24 volts is available if you have a 24 volt system.

Part number 409A6043 max torgue is 1,250 oz/inch
No load speed is 5200 RPM with a 370:1 planetary gear box.
Length is 4.331 inches. The weight is 14 to 21 ounces.
Max current is four amps. No load current is
0.29 amps. Aprox cost is $125 to $150.

I found something similar in the Servo Systems Co.
surplus catalog for $30 but somebody butchered the output
shaft making it difficult to get the torque out.
Also the mounting flange was reduced to only
two screws which is not enough. The torque was only
125 oz/inch. Many of the motors they sell are not fully
characterised in thier catalog so you need to know
eactly what it is you are buying.

Be careful when buying  surplus gear motors as many of them
are not planetary gear boxes and the output shaft is not
concentric with the motor shaft. They would be out
of balance when mounted on a variable pitch prop hub.

For those not familar flying a variable pitch prop
you adjust the pitch while watching the engine tach.
You then readjust the throttle until you get the
fuel flow where you want it and re-tune the pitch
etc. A MPG read out would be nice using the GPS
ground speed. (Brent needs a few more data ports
on his hand held IBMC PC Junior for flow meters and
altitude encoders.)

No real need to know exactly what the prop pitch is.

Globes phone number is: (937) 228 3171 FAX: 229 8531

Paul

A cheap alternate for a ground based system would be the motor
and gear train from a rechargeble drill, lots of torque - in some
cases with a settable release - too fast if anything - I do not
think I would fly with it tho - Vance

Roger Robertson wrote:

That rechargeable drill motor sounds like an excellent idea for a drive
motor.  They comes in a number of ratios, i.e. 1/4, 3/8 and battery size
determine that reduction ratio and it could be made rechargeable in the
air (Probably not necessary though- the batteries have amazing
capacity).  My experience with Globe has been good and they also build
limit switches into some models.  There are also some good linear
actuator manufacturers out there but one doesn't come to mind right now
and they are somewhat pricey. - Roger R.

Good point on that limit switch idea. We will have to give that some thought.
Perhaps a red light can come on when the current of the motor increases
when it stalls. Perhaps a solid state circuit breaker that resets automatically
when you release the double pole double throw momentary contact pitch
control switch. Solid state circuit breaker are very popular in aircraft these days.

Paul Lamar
 
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