Mailing List flyrotary@lancaironline.net Message #10683
From: John Slade <sladerj@bellsouth.net>
Subject: RE: [FlyRotary] Re: Compressor maps
Date: Mon, 23 Aug 2004 09:45:24 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Let's see if I understand this.
To help me read the map, I made a tiny spreadsheet (attached) to show lbs/min at various rpm
This tells me I have 23lb/min at 6000. So...
At SL and MAP 50 I have a PR of (30+20)/30 = 50/30 = 1.66
So on the map I read up from 23 till I hit 1.66 on the y axis and see that I'm on the bottom of the island.
 
Now go to 10000ft and set the MAP at, say 40. My PS is now (10+30)/10 = 40/10 = 4.0 which is off the scale. :(
 
Looking at the (compressor) MAP again I see that my max PR at 23lb is about 1.8, so working backwards my max MAP at 6000 ft is 18 if I want to stay on the island.  To get into higher PR's I need more rpm. I'd need 9000+ rpm to reach the top of the island where the available PR is about 2.5.
 
Doesn't sound right. Where did I go wrong?
 
Comments?
 
 
 
 
Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster