enginehistory.org Forum Index enginehistory.org
Aircraft Engine Historical Society Members' Bulletin Board
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Radial engine reduced power usage

 
Post new topic   Reply to topic    enginehistory.org Forum Index -> Technical Discussion
View previous topic :: View next topic  
Author Message
jschauer



Joined: 19 May 2004
Posts: 93
Location: Justin, Texas

PostPosted: Tue Mar 21, 2006 10:40    Post subject: Radial engine reduced power usage Reply with quote

Many warbird operators are using reduced power on takeoff hoping to ease the stress on the engines, any thoughts on this?
Back to top
View user's profile Send private message
kmccutcheon



Joined: 13 Jul 2003
Posts: 292
Location: Huntsville, Alabama USA

PostPosted: Tue Mar 21, 2006 21:53    Post subject: Reply with quote

I've always heard that at takeoff power the mixture was enriched to prevent detonation and that less than wide-open-throttle takeoffs with their high power at slow airspeeds could cause overheating.
Many operators now have both EGT and CHT on every cylinder, so as long as the temps stay reasonable, I can't see how the lower power settings can hurt. On the other hand, if the temps are higher then the operator is acutally increasing the stress on the engine by choosing the lower power setting.
The thing I don't know is whether the operators you are referring to are really monitoring their engines carefully enough to circumvent the "automatic" enrichment features without damage.
Do you have any more details?
_________________
Kimble D. McCutcheon
Back to top
View user's profile Send private message Visit poster's website
jschauer



Joined: 19 May 2004
Posts: 93
Location: Justin, Texas

PostPosted: Thu Mar 23, 2006 10:16    Post subject: Reply with quote

I fly as flight engineer on FIFI and we are discusing the use of reduced power to save the cylinders, I don't know enough to debate this. What you said in your reply makes sense for a carburetor'd engine but we have direct fuel injection, so we don't get the cooling effect of the fuel in the induction system. The last version of the KC-97 had charts for using 100/130 vs 115/145 when it wasn't available and they just reduced manifold pressure about 5" and torque also. We don't have torquemeters on our engines, just CHT mounted on the #1 cylinder. We can't afford to instrument all the cylinders, that would surely help though. The cylinders for the -57 engines, (BA series) are getting very hard to find. We are looking into re-engining to a CA series engine, but that is going to be a major engineering feat, ie. total new exhaust, slower turning propeller, different engine mount, longer engine case. We would gain a much better engine, torquemeters, more power, cooler running, more parts availability.
Back to top
View user's profile Send private message
sbezman



Joined: 13 Jul 2003
Posts: 12

PostPosted: Mon Mar 27, 2006 12:40    Post subject: Reply with quote

Pratt & Whitney's "The Aircraft Engine and Its Operation" has a discussion on this. As I recall, they advise against using reduced power for take-offs.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    enginehistory.org Forum Index -> Technical Discussion All times are GMT - 6 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group