Go Back  PPRuNe Forums > Non-Airline Forums > Private Flying
Reload this Page >

Manifold Air Pressure

Private Flying LAA/BMAA/BGA/BPA The sheer pleasure of flight.

Manifold Air Pressure

Old 23rd Mar 2014, 20:40
  #1 (permalink)  
Thread Starter
 
Join Date: Jul 2011
Location: Kent
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Manifold Air Pressure

Hi All,

I'm trying to understand the process for flying with a constant speed prop on a Rotax 912 ULS. There is hardly any information on this in the POH of the aircraft concerned, but I found this in the Rotax operating manual:

https://www.dropbox.com/s/g5ojged3nl...M%20Curve.tiff
https://www.dropbox.com/s/5rn30esf3f...M%20Table.tiff

From my understanding, I should choose a desired RPM for the fuel burn/speed I want, and set the manifold pressure according to the graph or the table. Am I correct to assume this? Also, I'm aware the MAP will decrease as I gain altitude, but what I am uncertain with is whether I should maintain the MAP shown on the graph (for my required RPM) regardless of my altitude, by advancing the position of the throttle as I gain altitude? I hope this makes sense and any help would be greatly appreciated.

Josh

Last edited by flyer96; 23rd Mar 2014 at 20:43. Reason: Fix broken image links
flyer96 is offline  
Old 23rd Mar 2014, 21:09
  #2 (permalink)  
 
Join Date: Aug 2000
Location: S Warwickshire
Posts: 1,214
Likes: 0
Received 0 Likes on 0 Posts
Don't forget that you'll need a differences training sign-off for the controllable prop, so your instructor should take you through the subtleties of operation.

You will normally climb at full throttle and, when levelling off either maintain full throttle or throttle back to just below the desired cruise MP, then when you set the cruise RPM the slight gain in MP should bring you close to the desired setting.

Generally at about 8000' or above you will probably want full throttle and control power with RPM as you won't be able to achieve more than about 21-22" MP. All this assumes non-turbo.

High MP and low RPM is the most efficient and quietest, so long as you stay within the approved limits.
Mark 1 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.