Accessory Drive

[drumwilldrum]

Hi All, 

Is there a reason other than simplicity that all DIY/Hobby-scale turbines have separate battery powered accessories rather than driven accessories?

I understand that at small scale and high rpm radial power take off shafts would not be practical, but surely concentric/epicyclic gearing could be used to distribute power from the rotor to a gear driven oil/fuel pump and a starter/generator? 

Something similar to as found in APU's. 

I have a vague idea to build something 'self contained' if you like.. 

Thanks
Will 

[racket]

Hi Will

Gearing for a DIY'er isn't simple , its not the easiest even when dealing with relatively low freepower rpm , but theres no reason why you can't try

Cheers
John

[stoffe64]

This is the tornado aircraft SPS GEARBOX ,the T312 APU is connected to this on that big Mount with a clamp.
It is here i Will connect my T312 APU.
Cheers/Stephan

[smithy1]

Sept 14, 2020 21:38:08 GMT -5 drumwilldrum said:

Hi All, 

Is there a reason other than simplicity that all DIY/Hobby-scale turbines have separate battery powered accessories rather than driven accessories?

I understand that at small scale and high rpm radial power take off shafts would not be practical, but surely concentric/epicyclic gearing could be used to distribute power from the rotor to a gear driven oil/fuel pump and a starter/generator? 

Something similar to as found in APU's. 

I have a vague idea to build something 'self contained' if you like.. 

Thanks
Will 

I think the main reason they don't is simplicity and cost.....the cost of doing so would outweigh the possible benefits. Plus....some of these little RC engines are capable of ~1/4 million rpm, so a little gear train hanging off anything spinning that fast would have to be engineered to perfection and have a lube supply to go with it. Not easy to do. A separate starter and electric fuel pump is relatively easy.

Smithy.