RCU Forums - View Single Post - Sebart Mini Avanti w/ K45 build thread
View Single Post
Old 05-13-2015, 02:02 PM
  #30  
Eddie P
My Feedback: (4)
 
Eddie P's Avatar
 
Join Date: Feb 2003
Location: Reno, NV
Posts: 1,915
Likes: 0
Received 2 Likes on 2 Posts
Default

Jack those 10s numbers are fantastic. That thing is gonna be killer at that weight.

Regarding EDF and turbine thrust just because it was brought up: Thrust is thrust. EDF's run up against exhaust speed, true, (like prop pitch speed for warbirds) but it doesn't effect thrust at most normal jet flight speeds as long as the exhaust speed is reasonable and most setups these days give way more than reasonable results.

Most of the fast efflux speed in a turbine is un-usable, because thrust limits will be met by airframe drag well before the efflux speed is matched. The dynamic drag produced by the jet airframe is typically going to very high at around 200mph or so. Often, for 1:1 or higher thrust engines, we meet the equal value of (newtons of ) drag produced by the airframe as produced by the engine thrust below 200 mph on most scale or "beefy" airframes. Even though efflux speeds are 700 mph.

EDF on the other hand, even though we may only get 250mph plus on efflux but we can use it all (well 80 percent of it or so) and top out pretty well sub 200 mph assuming our thrust numbers are high enough to meet airframe drag at speed. 9 pounds thrust is 9 pounds thrust. In flight, thrust will change as efflux speed is approached but assuming we have enough head room and maintain thrust we have excellent performance.

Everything I say is anecdotal and off the cuff, it's just a commentary. There is good published data out there though, for those with interest.

Last edited by Eddie P; 05-13-2015 at 08:17 PM. Reason: My initial iPhone post was garbage.. needed clarification