Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!cica!tut.cis.ohio-state.edu!att!cbnews!military From: vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET (Bob Smart) Newsgroups: sci.military Subject: Re: Fighter engine smoke Summary: F-15 engines Message-ID: <7938@cbnews.ATT.COM> Date: 5 Jul 89 12:36:50 GMT References: <7740@cbnews.ATT.COM> <7832@cbnews.ATT.COM> <7874@cbnews.ATT.COM> Sender: military@cbnews.ATT.COM Organization: Verdix Corporation, Chantilly, VA Lines: 61 Approved: military@att.att.com From: vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET (Bob Smart) In article <7874@cbnews.ATT.COM>, gardiner@umn-cs.CS.UMN.EDU (David Gardiner) writes: > > > From: gardiner@umn-cs.CS.UMN.EDU (David Gardiner) > A rule in the board game "Flight Leader" indicates that the engines > used in US F-15s are only smokeless if they are tuned appropriately. > Apparently, this limits engine life so that most or all of the engines > have been "detuned" to extend engine life. Does anyone know (a) if this > is true and (b) any more details? > > David Gardiner The answer got long so there is a one line summary at the end :-) Having put in 6 years fixing Eagles from 1976-82 I think I may have a few details that can help here. The answer to a) is YES. In 1976-77 one of the biggest problem areas we had (besides lack of parts) was the engines. THe F-100 was having stagnation problems on a regular basis. at the same time the engines were not lasting as long between overhauls as they expected. at the time the overhaul interval was very short because of the engines was new to the inventory. The stagnation problems were causing the engines to be removed even more often. To reduce wear &tear they retuned the engines at about 97%. The stagnation problems were fixed and things stayed hunky-dory. Then about 1980 there was a SEVERE engine shortage. TheCarter administration had made deep cuts in spares procurement and in long leadtime procurement for new aircraft. Then there was a labor problem either at Pratt & Whitney or one of there major suppliers. The pipeline for F-100 engines dried up completely. At one point we were removing engines from existing aircraft and sending them to St Louis to be installed in new aircraft that were coming off the assembly line. You see engines are GFE (government furnished equipment) and the Air Force had to provide them to keep from being charged for storage of the A/C. At one point our wing ( and I was told every other F-15 wing) had to send 23 aircraft to Warner Robins AFB to have all removable systems like radar radio, ECM, and engines stripped from them 'temporarily' to restock the supply system. We finally got the planes back about a year later but some of them never were 'right' again. It was easy to tell which planes had been used for this, most of the fleet had 4,000+ hours on the planes these birds had about 1,500. Anyway in the midst of the 1980 engine shortage the word came out to detune the engines to about 95% to extend the time between overhaul. The first detuning caused some smoke on some engines but the second one caused most to smoke. But the problem is relative. a smoky F-15 puts out only a little more than an F-4 with the new 'smokeless' engine mod. and the F-15 can be fixed on the trim pad in about 2 hours peacetime ( 10 minutes if the engine troops know that it's the real thing). I know planes that were preped for exercises like Gallant Eagle and Red Flag to 100% aand the smoke went away ( as well as markedly better performance according to the pilots) of course there were no official records kept of this since the book required the lower settings. The short answer is smoky engines last longer in peacetime flying since the engines aren't being stressed to their limits. But if the whistle blows the engines will be back to clean & mean. Bob Smart (bsmart@verdix.com)