Originally Posted by
olnico
What about
:
Idle thrust increased by 30%
Engine weight increased by 40%
Fuel consumption increased by 20%
I'm not a really big fan of up sizing just for the sake of it. Never loose the prospect that you'll have to land your model at some point. Coming in the flare 30% faster is a good recipe for bounced landing, high energy impact and premature airframe/ gear wear.
I'm sure you've seen that in your flight carrier before...
This is all discussed here:
http://www.ultimate-jets.net/blogs/j...ur-application
"Idle thrust increase by 30%" Not sure where you got this number, but I was told the difference between K180 & 140 was very negligible. Not saying you're wrong, but where did you get it?
"Engine weight increased by 40%", I'm not a big fan of can-to-can comparisons, you'd really have to go airframe specific to get the big picture. Design/wing area are the biggest factors when figuring your (percentage) weight increase & performance penalty factors.
"fuel consumption increase by 20%", If your numbers are right, good job, but how did you get them? You would have to take a K-180 & detune it to the same thrust as the M-140 them measure consumption over time. I haven't seen that done yet, so I don't have the necessary info to comment.
"Flare 30% faster" again, where do you get these figures? AIRFRAME SPECIFIC! a 30lb model increasing to approx 31lbs (turbine weight difference) is a 3% increase. The only experience I have with that is full scale, & I can tell you the difference between landing speeds with a 3% increase is almost unnoticeable.
I think the OP will love his new M140 (not trying to talk him out of it), but in the event he decides it's time to try that large Ultra Lightning, or Skymaster, or runs into that good deal in the classifieds, he will have to come better than 31lbs thrust. Maybe he already has a big block in his fleet, in that case I would love the small efficient M-140 (it may be my next turbine..lol)