In response to Neillys query on props here’s the beginning of a few posts on props. If you’re not into technical stuff, best you leave this post now!
Drawing 1. Imagine your standing in line with the edge of the prop looking along a blade. Here are a few terms you’ll need.
Drawing 2. Velocity diagrams – just lines representing direction and speed. The longer the line the greater the speed.
Drawing 3. Why you need different pitches for different flight conditions, and why fixed pitch props are inefficient.
If you don’t understand what I’m getting at, ask, because your not stupid, it’s me that’s probably missed something in the explanation!
KeithMac
Attachments:
By: keithmac - 6th October 2002 at 10:58
RE: Propellers – Pt 1
The answer is very very much better. A fixed pitch prop is a compromise. The compromise they went for was to have a fairly course pitch which gave good performance in combat. This however made for very long take off runs (for the type of aircraft) and the prop was generally very inefficient. You have to remember though, that the speed ranges of the aircraft in those days was only around 200 mph. I’ll be posting Pt 2 of my post later, where I’ll deal a little more with variable pitch props and blade twist.
KeithMac
By: Wombat - 6th October 2002 at 07:38
RE: Propellers – Pt 1
Keith
Excellent info. I have a question for you on this subject.
Given that the power output of the engines used in fighters during world war I was quite low, how would fighters like the SE-5A, Camel, Spad, Albatross etc, have performed if they had been fitted with variable pitch props? What sort of pitch did they have as they were fixed pitch, generally two bladed timber jobs?
Regards
Wombat
By: neilly - 5th October 2002 at 09:14
RE: Propellers – Pt 1
Hi Keith,
Excellent job! I hope you don’t mind, I’ve printed the above post out to keep, for future references.
Many thanks,
Neilly
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October 4, 2002 at 9:24 pm