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Post by lumpy on Feb 8, 2013 22:57:26 GMT 12
I seem to remember the RAAF was involved in a modification programme on the T-56 engines in their fleet to reduce the exhaust smoke. Mods to the combustion cans altered/improved the airflow through the hot section and I guess, improved the burn characterstics. As Raymond says, these engines aren't new - in fact the design turns 60 next year! I worked on both models of the RNZAF T-56 and the civil Allison 501 during my time with SAFE Air. A truly superb engine. I remember the compressor of an industrial T-56 visiting the shop for a dynamic balance. It was much beefier than the aeronautical version and was used in some sort of powerplant capable of 8000hp and designed to run for months on end. I was also involved in performance testing these engines at the Air NZ engine centre in Auckland. The test bed was at nearing the end of its life but its history was quite fascinating. It was, at the time, purely for testing the T-56 but there was clear evidence of its past. Our control console was at the same level as the big engine when it was bolted to its mountings. We were able to observe the engine through a thick double glazed window. In a room below was a console that was used to start, run and test the Iroquios Lycoming T-53 many years earlier. Inside the 'cave' itself were mountings that used to support the early P & W turbo jets from the DC-8. In the room where we tested the T-56, we sat with our backs to the Bristol Hercules test console which was still complete. It even had a large set of scales that held an oil tank. Somehow, this was used for accurately determining the oil consumption of the engine on test. The whole facility was nearing the end as it had been earmarked for conversion to another purpose. We would often base two or three engineers in Auckland for several days testing repaired and overhauled engines. If the squadrons weren't demanding engines in a hurry, we'd have a handful of engines up there at a time and chip away at them until they were all serviceable. Good times. I can lay claim to pushing the throttle on a J52 ( Skyhawk ) to ever 90 percent ( in the test bed ) , as an ATC cadet . Turned out the guy I went to work for years latter , may well have rebuilt that same engine . ( he came to the "dark side " I didnt " follow the light " ;D
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Post by davidd on Feb 9, 2013 10:57:16 GMT 12
People have been noticing the smoke trails left by P-3s for a very long time. Who remembers Sir Francis Chichester? In his autobiography (published about 1970?, which I unfortunately do not possess a copy) he had a portion devoted to detailing his around the world solo voyage in his small yacht (named "Gipsy Moth" or similar) and whilst south (?) of New Zealand he was pleased to see an RNZAF P-3 roaring overhead (perhaps deviated from their assigned patrol to say hullo, although I have a funny idea he may have been battered by a storm and concern had been expressed as to his general condition). Regardless, he noted that he thought that this aircraft needed its carburettors adjusting as in his opinion a modern aircraft should not leave such long trails of smoke behind each engine. You got the feeling that Sir Francis had not followed aviation developments in great detail since he departed the aviation scene in the mid-1930s, but he did know his original Gipsy Moth never smoked that much. David D
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Post by alanw on Feb 11, 2013 13:34:23 GMT 12
The Soviets called US aircraft from the 60's era (probably early 70's to) "Smokers", owing to the trails they left behind
During Vietnam, the exhaust trails often allowed the "eyes" on ground to give missile sites or fighters, vectors, due to the Smoke trails remaining for some minutes after aircraft had gone by.
From my reading etc, the worst "Smokers" were the F4 Phantom. this youtube shot is of a Hellenic F4 but you get the idea
This shows a USN F4 even at a distance you can see the smoke
Interestingly once the British changed their F4's to the RR Spey the smoke disappeared.
The B 52 (D/G/H) doing a full alert take off can make a mess. Check out this youtube video -water injected takeoff
Can you imagine a B 52 doing a take off like that here? Certain folk would have conniption fits ;D ;D
Regards
Alan
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Eng
Flight Lieutenant
Posts: 81
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Post by Eng on Feb 15, 2013 19:53:42 GMT 12
There is a very valid reason why there are quite visible smoky trails behind the Orions . It apparently stems from the practice first acquired from the RAF Beverly Blackburn aircraft -a bloody great hulking transporter which when one was fortunate enough to be a passenger in was similar to attending a service in St Pauls Cathedral minus pilots notes. The engines on the Blackburn were of the external lubrication type. The oil was sprayed on the exterior of the crankcase and sort of seeped in to where it was bacly needed, the excess just dropped off and in most cases exuded through the cowlings. The navigators on this aircraft had it fairly easy. They only had to plot the course to the destination then the pilot just followed the oil slick home . The Orion navigators being rathere crafty and not really relying on their personal Tom Toms follow the same procedure. I trust this has been of some help. Eng
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Post by ngatimozart on Feb 16, 2013 13:50:18 GMT 12
B52 at full noise. Pinched the photo from the Military Photos Facebook page.
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Post by suthg on Feb 16, 2013 15:58:55 GMT 12
Someone left the choke on... LOL! Or was he burning bunker fuel? Nice pic -well found!
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Post by beagle on Feb 16, 2013 16:16:56 GMT 12
pretty sure I haven't seen an orion that bad. Think the MFC would be scratching his head if it got that bad.
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Eng
Flight Lieutenant
Posts: 81
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Post by Eng on Feb 16, 2013 16:45:02 GMT 12
That marvellous pic of the Orion with the smoky Joe tail looks very much like he has just completed a very successful "Prince of Wales feathers" demo. Not too sure where the other three got to ! Wifes washing ruined . Eng
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Post by ngatimozart on Feb 16, 2013 18:24:08 GMT 12
That B52 looks like its burning West Coast coal. ;D
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Post by mumbles on Feb 16, 2013 23:04:27 GMT 12
Someone left the choke on... LOL! Or was he burning bunker fuel? Nice pic -well found! It was mostly the earlier turbojet engined models of B-52 and KC-135 that did this, thanks to the water injection used to provide extra thrust at full throttle. It resulted in patches like this: faito.net/gallery/random/burnwaterHere is the turbojet version Minimum Interval Take Off from 1963 in a clip from "A Gathering of Eagles": And the 2009 equivalent with turbofan powered B-52H models: As to the F-4, this is one of my favourite youtube clips for a number of reasons, but one is that you can tell when he is in and out of afterburner, because in afterburner the smoke disappears. I understand that in Vietnam some F-4 crews would fly in minimum afterburner as a routine when in a combat area to reduce the smoke signature.
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Post by skywarrior on Feb 24, 2013 17:02:10 GMT 12
On a serious note the airforce is still seriously considering a mod to these engines but it is slow going. As has been stated the problem lies in the old combustion can design and its inability to efficiently burn the fuel. So a new can design is being considered that will allow more air to mix with the fuel and produce more efficient burning. But again it is slow going.
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fergi
Flying Officer
Posts: 55
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Post by fergi on Feb 24, 2013 19:20:43 GMT 12
But the engine is so successful why change it now, could understand if we needed to be covert but in modern times there is no real problem.
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