Jump to content
Sign in to follow this  
rnbraud

Newbie question on auto-conversions and Props?

Recommended Posts

(caution newbie)

Why do auto conversions require PSRU's. I understand that auto engines rev at a higher RPM, but, is the need to reduce the propellor speed for the sake of the prop or the engine?

 

I guess I am wondering if normal prop cruise speed is between 2500-3000 rpm why not just put a different prop on an auto-conversion which operates at the 4000-6000 rpm range?

 

Or, is it possible to add more smaller blades to a prop, i.e. 5, 6, or 8 blade props of a smaller diameter, which would either slow down the engine or would be able to operate at higher rpms.

 

Just asking.

Share this post


Link to post
Share on other sites

Why do auto conversions require PSRU's.

Common props that you can buy operate in the 2,000 RPM range, and that's why you need the PSRU. I believe you're entirely correct that you could possibly use a different prop geometry, but as the prop diameter was reduced (with more blades added), you would begin to approach the need for and design of a ducted fan.

 

Check out Perry Mick's attempt to do exactly this on a Long-EZ powered by a Mazda rotary. www.ductedfan.com The results were not as desired, and Perry has since removed the fan in favor of a PSRU setup.

 

This is not to say that the concept is bad -- I believe it could be perfected with enough time, money, and energy (pun intended).


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Long-term:  Building a Cozy Mark IV

Share this post


Link to post
Share on other sites

Yep, kinda came to the same conclusion. My main driver for this was with the PSRU, however, there still needs to be some way to attach the prop to the crank which would mean some sort of housing.

 

PSRU's are more comples than asimple connection to the crank, but if you still need a housing, and therefore bearings and such, than a PSRU isn't all that much more complex.

 

Later.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

The Canard Zone

×
×
  • Create New...

Important Information