PPRuNe Forums - View Single Post - Reaction Engines Sabre/Scimitar
View Single Post
Old 13th Mar 2011, 17:18
  #29 (permalink)  
Machinbird
 
Join Date: Jul 2009
Location: Not far from a big Lake
Age: 81
Posts: 1,454
Likes: 0
Received 0 Likes on 0 Posts
Jane-Doh
First, I'd like to express my appreciation for making us old guys (at least this one) catch up on the more recent developments on the cutting edge of technology.

The formula you posted is not quite correct, but that is caused by the problems with cutting and pasting mathematical formulas with limited editing tools. The original formula read: T= 220(1+ 0.2*Machnumber squared)

This is the stagnation temperature formula expressed in terms of Mach number (Mn). In this case, the 220 is the assumed initial (Freestream) temperature Kelvin. Check out the Wiki on stagnation temp here:
Stagnation temperature - Wikipedia, the free encyclopedia
Using the formula for stagnation temperature T0, they have assumed a starting free stream temperature, and simplified into terms of Mach number. (Good enough for back of the envelope work until you start to get disassociation of the working fluid)
Machinbird is offline