X-Mozilla-Keys:
Thanks Marc for all the info. How does the GoodYear Eagle stand
up in comparision to the others? Narrower belt same HP?
Higher RPM possibly?
The 1000 hour life is interesting.
All this does not sound good for a belt PSRU for your average run of
the mill 13B powered airplane.
Marc Pedings wrote:
Very True! The service life is for 255HP in a class 3 service environment (24/7 operation
and exceeding 200% of the rated HP 30% of the time). I would look into the Polychain GT
for this. They have a higher HP rating for a given width than the Eagle PD's. Our primary
concern is the DriveR sprocket for it is the limiting factor of our drive capacity. Here
is a comparison:
At 4000RPM, 28 tooth DriveR sprocket, average center distance of 9.5 " Both belts are
comparable at 14mm tooth pitch.
EaglePD: 221 HP x .73 length correction = 161.33 HP for 2.75" width belt
Polychain: 254 HP x .73 length correction = 185.42 HP for 2.68" width belt
Here is a 4.92" width setup for the Polychain, 2.14 Ratio, 6400 RPM.
Please note that this RPM is not published, but I used regressive RPM per HP units to
calculate this drive capacity at 6400 RPM
RPM HP RPM-HP unit
2400 / 319.0 = .1329
3200 / 398.1 = .1243
4000 / 467.8 = .1167
4800 / 528.9 = .1102
5600 / 586.8 = .1048
6400 / 648.3 = .1013
648.3 HP at 6400 RPM x .73 belt length correction = 473.25 HP
Note the DriveR sprocket will see 8128 FPM !!! Cast iron will not stand up to this, but
they recommended T6 for the drive I specified earlier.
I really think this is doable with this drive! Given you are around double the rated HP,
your service life will be around 10% or 100 hours given cooling is sufficient. I also
figured about a 3-4% loss to the drive. Worst case is 4%, therefore we have 29,840 BTU of
heat! With that heat, cut the service life by 50% and you have about 50 hours. I really
think this is worth investing into!
For the Reno racer a static
analysis based on the belt breaking strength as suggested by Matt
Cosman is called for IMHO. We might also get a little more life
with Teflon coated sprockets like your average frying pan has.
Maybe?
Marc Pedings
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