F4 Phantom
Join Date: Mar 2008
Location: Outside the Fence
Age: 71
Posts: 373
Likes: 0
Received 5 Likes
on
4 Posts
With the FGR2 if you found yourself a bit tight on the finals turn I found that switching to 12th stage could tuck you in nicely thus avoiding the embarrassment of flying through the centreline.
Originally Posted by wiggy
Must admit it's going back a long time and my memory might be playing tricks but I have the hazy recollection that the F-4Ms (FGR 2s) retained the feature but with the option to switch it off or manually overriding it.
If I remember rightly the bleed system was locked in 12th stage with full flap selected to avoid changing stages on approach. On the FG Mk 1 aircraft I think when the nose leg was fully extended, 12th stage was overridden automatically and the system was locked in 7th stage so that maximum thrust was available on the catapult. In normal flaps up, and I think half flap, the system operated in 7th stage when the pressure was above 85 psig and 12th stage when it was below that figure.
In the mid to late 80's I attended at meeting at Boscombe Down to discuss a hot weather trial in Cyprus to extend the maximum all up weight for approach conditions. I can't remember whether this was for single engined or twin engined approaches but one of the problems was that at high AUW and high OAT you could end up needing a thrust somewhere between Mil power and Min reheat which was quite a big step. The proposal was to play tunes on the bleed stage selection in order to try and bridge the gap. I got a bit concerned about what was being proposed for the trial as there seemed to be some risk that the pressures could drop to the point where boundary layer control (BLC) became ineffective. In this respect I was being overly cautious by drawing on my 'other aircraft' background which was the Buccaneer, where loss of BLC pressure on approach could be catastrophic.
Don Headley politely told me to get back into my systems engineers box and leave the handling aspects to him and the aerodynamicists. ( I think he was a bit concerned about the prospect of missing out on a trip to Cyprus) However he was quite right. In the Buccaneer it was primarily the trailing edge of the wing that was 'blown' and loss of BLC pressure resulted in the aircraft pitching up, increasing the angle of attack and aggravating the stall. In a Phantom it is primarily the leading edge of the wing that is blown so loss of BLC pressure is much more benign since the aircraft will pitch down rather than up.
I was also involved in a major investigation into failures of the engine bleed off-take ducting, a piece of pipework known to us as the Dalek duct which sat under the engine and connected to the trailing edge BLC duct outboard and the leading edge and ECS ducting in the keel. This duct used to break at the trailing edge connection resulting in hot air leaks and fire warnings. There were also failures of the brackets holding the bleed air ducts inside the bypass casing.
Rolls Royce proposed a joint trial at Holme on Spalding Moor where they would strain gauge their brackets and we would strain gauge the off-take duct. The instrumentation strain gauge data would be transmitted directly back to Derby over the telephone system for analysis. This was state of the art rocket science around 1980. The strain gauged engine and duct were fitted and we ran the aircraft but the phone system would not transmit the data fast enough so the proposed trial was initially a failure. However in co-operation with the Rolls Royce rep, Alan Shinwell, we proposed an alternative method to fix a number dial gauges under the engine on a dexion bridge and observe the movement of the ducting during an engine run. The Rolls Royce Derby instrumentation engineers were horrified at this idea, saying this was a development engine and much too dangerous. However we said if they had been happy enough to fit this engine in our aircraft, albeit only for ground runs it could not be that risky.
The ground runs took place and it quickly became clear what the problem was. At high power setting the engine moved forward slightly under the thrust loads and twisted about the inboard thrust mount. The core of the engine expanded backwards and the result of these two effects was that the bleed offtake duct was being loaded in torsion, i.e. twisted, but the bellows at the trailing edge connection were not designed to tolerate torsion, only bending. As a result of the trial we proposed a modified bleed offtake duct which had a sealed bearing and would allow the torsional movement. However MoD decided it was too expensive and persisted with the occasional failure of the original duct.
Standing directly under a Phantom Spey running in max reheat was always an exciting event. I can remember Alan Shinwell telling me that the pressures and temperatures inside the bypass duct on the Spey were higher than in a Lancashire boiler, which was I think typically about 20 times thicker than the bypass duct.
Walbut
In the mid to late 80's I attended at meeting at Boscombe Down to discuss a hot weather trial in Cyprus to extend the maximum all up weight for approach conditions. I can't remember whether this was for single engined or twin engined approaches but one of the problems was that at high AUW and high OAT you could end up needing a thrust somewhere between Mil power and Min reheat which was quite a big step. The proposal was to play tunes on the bleed stage selection in order to try and bridge the gap. I got a bit concerned about what was being proposed for the trial as there seemed to be some risk that the pressures could drop to the point where boundary layer control (BLC) became ineffective. In this respect I was being overly cautious by drawing on my 'other aircraft' background which was the Buccaneer, where loss of BLC pressure on approach could be catastrophic.
Don Headley politely told me to get back into my systems engineers box and leave the handling aspects to him and the aerodynamicists. ( I think he was a bit concerned about the prospect of missing out on a trip to Cyprus) However he was quite right. In the Buccaneer it was primarily the trailing edge of the wing that was 'blown' and loss of BLC pressure resulted in the aircraft pitching up, increasing the angle of attack and aggravating the stall. In a Phantom it is primarily the leading edge of the wing that is blown so loss of BLC pressure is much more benign since the aircraft will pitch down rather than up.
I was also involved in a major investigation into failures of the engine bleed off-take ducting, a piece of pipework known to us as the Dalek duct which sat under the engine and connected to the trailing edge BLC duct outboard and the leading edge and ECS ducting in the keel. This duct used to break at the trailing edge connection resulting in hot air leaks and fire warnings. There were also failures of the brackets holding the bleed air ducts inside the bypass casing.
Rolls Royce proposed a joint trial at Holme on Spalding Moor where they would strain gauge their brackets and we would strain gauge the off-take duct. The instrumentation strain gauge data would be transmitted directly back to Derby over the telephone system for analysis. This was state of the art rocket science around 1980. The strain gauged engine and duct were fitted and we ran the aircraft but the phone system would not transmit the data fast enough so the proposed trial was initially a failure. However in co-operation with the Rolls Royce rep, Alan Shinwell, we proposed an alternative method to fix a number dial gauges under the engine on a dexion bridge and observe the movement of the ducting during an engine run. The Rolls Royce Derby instrumentation engineers were horrified at this idea, saying this was a development engine and much too dangerous. However we said if they had been happy enough to fit this engine in our aircraft, albeit only for ground runs it could not be that risky.
The ground runs took place and it quickly became clear what the problem was. At high power setting the engine moved forward slightly under the thrust loads and twisted about the inboard thrust mount. The core of the engine expanded backwards and the result of these two effects was that the bleed offtake duct was being loaded in torsion, i.e. twisted, but the bellows at the trailing edge connection were not designed to tolerate torsion, only bending. As a result of the trial we proposed a modified bleed offtake duct which had a sealed bearing and would allow the torsional movement. However MoD decided it was too expensive and persisted with the occasional failure of the original duct.
Standing directly under a Phantom Spey running in max reheat was always an exciting event. I can remember Alan Shinwell telling me that the pressures and temperatures inside the bypass duct on the Spey were higher than in a Lancashire boiler, which was I think typically about 20 times thicker than the bypass duct.
Walbut
Join Date: Oct 2003
Location: Somewhere
Posts: 502
Likes: 0
Received 0 Likes
on
0 Posts
Amen to that Walbut. Had a bypass duct blow on me in a 92 Sqn F4 on a Taceval mission. Bust some fuel lines, causing my wingy to ask me if I had burner lit. On replying negative, he said "well, in that case, you're on fire then". We legged it to Laarbruch, jammed it into the cable. By the time I was down the ladder, my trusty WSO was already halfway through his first fag on the grass by the rwy........
Join Date: Jan 2010
Location: Forres
Age: 67
Posts: 185
Likes: 0
Received 0 Likes
on
0 Posts
I am researching the use of the F-4 Phantom by the USMC and hope to make contact with those who flew it to gather recollections and information. If you think you can help me please send me a private message and I will give you details of what I want to know.
Join Date: Jan 2003
Location: Leicestershire, England
Posts: 1,170
Likes: 0
Received 0 Likes
on
0 Posts
The USMC F-4 group on facebook might be worth a try?
https://www.facebook.com/groups/268388301611/
-RP
https://www.facebook.com/groups/268388301611/
-RP
