>>     Do yourselves a favor and search out an Enstrom helicopter to
>> study
>>     their system. It has been in use for a very long time with great
>>     success. Enstrom uses the belt as the clutch and this solves the
>> tension
>>     problem for Enstrom. The polyV provides damping of torque pulses.
>> The
>>     system should be no more complex nor heavier than a cog belt
>> system with
>>     the exception of the tensioning device.
>>
>>     This past Saturday I examined the "Belted Air Power" unit on a V8
>>     engine. It is quite clean and in use for a long time. However I
>> want
>>     to use the polyV belt system as I think there is less risk of
>>     catastrophic failure. With the cog belt improper tensioning can
>> raise
>>     havoc with the belt teeth. The cog belt may not provide the
>> damping
>>     qualities of the polyV belt.
>>
>>     Bob Y
>>
>>     There are way more Robinsons flying then Enstrom :)
>>     Probably a 100 times as many :)
>>
>>     The V-ribbed provides damping too. Probably it is more efficient
>>     than a poly V as the belt is thinner so there is less
>>     flex and heat build up. However not recommended for a clutch type
>>     helicopter application.
>>
>>     Paul Lamar ...No rotor no motor.
>>
>> ----------------------------------------------------
>>
>> Bob,
>>
>> That's my thinking exactly -- I would much rather go with v-ribbed, or
>> even multi-v, than cog belt.
>>
>> The difference is that an improperly tensioned v-belt will merely
>> slip,
>> while the cog belt will quickly self-destruct.
>>
>> A cog belt will still provide some torsional damping, just as a chain
>> drive will, but v-belts are better in this regard too.
>>
>> I really can't understand why cog belts are so popular. The only time
>> you really need them is when you need synchronicity, which you don't
>> with a prop drive. Otherwise they bring a lot of negative baggage.
>>
>> Regards,
>>
>> Gordon.
>
> Simple question leads to a really interesting discussion. What belt
> section and width (# ribs) is it going to take to transmit the ~200 hp?
> What kind of center distance can be used? What kind of static tension
> is required?
>
> Ken Bauman
>
> One more question. 200 HP at what RPM?
>
> -- > Paul Lamar ...No rotor no motor.


I was thinking 6500. Where is the chart from?

Ken Bauman

Machinery's Hand Book.

Does anybody recognize this helicopter?


Paul Lamar ...No rotor no motor.

Could be a Hughes-Schweitzer.
The belt problem with rotary engines is the high RPM and thus high belt
speed. The helis run opposed engines with about 2700 RPM max.

Colin Smith


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