From: zenadsl6186@zen.co.uk   
      
   johnhare  wrote   
   > "Peter Fairbrother"  wrote   
   >>   
   >> BTW - I was looking at teeny jets recently, around the 100N size. They   
   >> have a T/W around 11, and exhaust velocities around 1150 m/s. Cost a couple   
   >> of kilobucks. But, they have radial compressors :(.   
   >>   
   > What is wrong with radial compressors?   
      
   They don't accept high inlet velocities as well as axial ones.   
      
   ? Am I right? No-one since Whittle has used radials by choice, but my   
   understanding may be flawed.   
      
   I think teeny jets have to use radials, not axials, for Reynold-number type   
   reasons.   
      
   > Any idea on the turbine inlet temperatures?   
      
   No, sorry. EGT max is only 700 C tho'.   
      
      
      
      
   Talking of models, I used to use Jetex "augmenter tubes" when I werre a lad.   
   They "captured and entrained" air with the the Jetex exhaust, and heated and   
   accelerated it (supposedly!. Long story, but they did actually work, and far   
   better than the static figures show when at speed and tuned up). Here's a   
   link:   
      
   http://jetex.org/motors/motors-accessories.html   
      
   The math possibilities are indubitable for an air-breather (tho' it need not   
   even "breathe" the air, just heat it and expel it, like an aircraft uses the   
   air all around for lift).   
      
   (Jetex motors were refuellable solid-fuel rocket motors, used mostly to   
   power model aircraft as opposed to rockets. They were fairly long-duration,   
   about 10 seconds or more. I've been told they are still made.)   
      
      
      
   --   
   Peter Fairbrother   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)