Aircraft General Discussion

[Martin ConnellyParticipant @martinconnelly55370]

I saw the BBMF 80th anniversary flight heading back to Coningsby this afternoon after their flypast in London. They must have done a few other flypasts on the way back for me to see them. I am not near a line drawn from London to Coningsby.

Martin C

[martin perman 1Participant @martinperman1]

I was at my Brothers with my sister and our wives and husband in Olney Bucks when the BBMF passed over his house at 12:45 approx on their way home.

Martin P

[Michael GilliganParticipant @michaelgilligan61133]

Wasps using pitot tubes : **LINK**

https://www.smithsonianmag.com/smart-news/australia-wasps-pose-danger-airplanes-180976424/

MichaelG.

[Martin ConnellyParticipant @martinconnelly55370]

Odd contrails in the sky yesterday. Reports are it was air to air refueling practice involving Typhoons.

Martin C

[Cornish JackParticipant @cornishjack]

Martin – Possible, but AAR practice is usually done on a 'race-track' tow-line in the Wash area. We (N Norfolk coast) seem to get daily 'one-on-ones' overhead.

rgds

Bill

[Robert Atkinson 2Participant @robertatkinson2]

Looks like the ends of 3 race tracks to me so AAR seems likely. Only the end of the racetrack is in the contrail area.

Robert G8RPI.

[Michael GilliganParticipant @michaelgilligan61133]

A nice landing : **LINK**

https://www.bbc.co.uk/news/av/world-us-canada-55184326

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Ar234

**LINK**

https://www.smithsonianmag.com/smithsonian-institution/lightning-speed-and-agility-germanys-ar-234-blitz-jet-bomber-was-success-ultimately-failed-180976581/

MichaelG.

[JAParticipant @ja]

Posted by Michael Gilligan on 21/12/2020 09:30:04:

 

Ar234

**LINK**

https://www.smithsonianmag.com/smithsonian-institution/lightning-speed-and-agility-germanys-ar-234-blitz-jet-bomber-was-success-ultimately-failed-180976581/

MichaelG.

A very busy pilot and bomb aimer (same person, possibly with very few flying hours), one half ton bomb and could only fly flat out (the engines were likely to flame out if throttled back and there were no air brakes). So this was the German super bomber. Not wonder they never hit the Remagen bridge.

Don’t think about the ME262

JA

Edited By JA on 21/12/2020 13:26:21

[Ex contributorParticipant @mgnbuk]

So this was the German super bomber

Don’t think about the ME262

Given the conditions that they were operating under at the time, it is quite amazing that such advanced projects actually made it into limited operation at all. Had it not been for misguided interference at the very top substantially delaying the project, the 262 could have made more of an impact earlier.

IIRC the Me262 had received an updated, automated, engine control system before the end of the war to improve engine life by operating the engines such that they didn't overheat or flame out when handled harshly. And with a life of between 10 and 20 hours due to the lack of exotic metals, I guess that an improvement in life was desirable – though with the overall situation at that point, it was probably academic.

I think that there is a wartime built 262 currently being rebuilt to fly with it's original Junkers engines. These have been rebuilt using modern, proven, metals in the highly stressed areas. There are a number of 262 replicas flying, but these use modern engines mounted inside "look-a-like" housings.

Ultimately it is the axial flow Junkers design that proved to be the best option for development into what we regard as the norm these days, rather than Whittle's centrifugal design.

Nigel B.

[Neil WyattModerator @neilwyatt]

It is remarkable that the German jet engines has flight times measured in hours, but there are Meteors and Vampires still flying today.

Neil

[SamsarandaParticipant @samsaranda]

Neil

The meteors and Vampires flying today are definitely not flying with their original engines, they will have been changed a few times but certainly their engines far surpass the life of the ME 262’s.
Dave W

[JAParticipant @ja]

Ignoring the lack of high temperature alloys there was an aweful lot wrong with the German jet engines.

The major one was the decision to develop the jet engine to start with. This was forced on the Germans who had no access to very high octane fuel which limited the development of their piston engines. The jet engine appeared to be the obvious solution. It was also considered to be simpler and cheaper to make. The result was an aeroplane like the ME262. The lowest relative speed between an ME262 and a B17 would have been around 270mph. The ME262 had four cannons each with a rate of fire of 700 rounds/min. If the pilot of the ME262 opened fire at 1/2 mile that makes a total of 28 rounds fired before it passed the B17.

The axial compressor was the Achilies heel of the Jumo and other German engines. Its pressure ratio was just over 3:1 compared with a Goblin's of 3.5:1 and 4:1 for a Whittle or Rolls-Royce compressor. The main problem with an axial compressor is starting it (not the engine). When running at and below idle the compressor is far from its design point: The front of the compressor is trying to swallow too much air and the compressor is likely to stall/surge. This made starting the engine very difficult and surging was alwaysa possiblity at any speed other than its design speed. This was the cause the engine's handling problem. The Allied axial compressors being developed during the war had a blow-off valve half way down the compressor. Later on variable guide vanes and two spool compressors also came into use.

The early Allied engines used centrifical compressors because of the known technology, superchargers, and ease of handling. The Allies problem with the jet is that they did not know what to do with it. They had air superiority any way.

It is interesting to note that only one country tried to evolve an engine from the German engines and that was France. It took them years. The Russians soon gave up and restarted the development of an pre-war engine. As a stop-gap they built Rolls-Royce Nenes and Derwents.

I think you will find that many Meteors and Vampires are still using original engines although I have to admit my working knowledge of such things is from over 15 years ago. I would sooner trust a Nene or Goblin than an early RR Avon as used in most of the Hunters.

Rant of the day over.

JA

[JAParticipant @ja]

Posted by JA on 21/12/2020 20:11:53:

Ignoring the lack of high temperature alloys there was an aweful lot wrong with the German jet engines.

The major one was the decision to develop the jet engine to start with. This was forced on the Germans who had no access to very high octane fuel which limited the development of their piston engines. The jet engine appeared to be the obvious solution. It was also considered to be simpler and cheaper to make. The result was an aeroplane like the ME262. The lowest relative speed between an ME262 and a B17 would have been around 270mph. The ME262 had four cannons each with a rate of fire of 700 rounds/min. If the pilot of the ME262 opened fire at 1/2 mile that makes a total of 28 rounds fired before it passed the B17.

The axial compressor was the Achilies heel of the Jumo and other German engines. Its pressure ratio was just over 3:1 compared with a Goblin's of 3.5:1 and 4:1 for a Whittle or Rolls-Royce compressor. The main problem with an axial compressor is starting it (not the engine). When running at and below idle the compressor is far from its design point: The front of the compressor is trying to swallow too much air and the compressor is likely to stall/surge. This made starting the engine very difficult and surging was alwaysa possiblity at any speed other than its design speed. This was the cause the engine's handling problem. The Allied axial compressors being developed during the war had a blow-off valve half way down the compressor. Later on variable guide vanes and two spool compressors also came into use.

The early Allied engines used centrifical compressors because of the known technology, superchargers, and ease of handling. The Allies problem with the jet is that they did not know what to do with it. They had air superiority any way.

It is interesting to note that only one country tried to evolve an engine from the German engines and that was France. It took them years. The Russians soon gave up and restarted the development of an pre-war engine. As a stop-gap they built Rolls-Royce Nenes and Derwents.

I think you will find that many Meteors and Vampires are still using original engines (engines are frequently changed in aircraft so original means type) although I have to admit my working knowledge of such things is from over 15 years ago. I would sooner trust a Nene or Goblin than an early RR Avon as used in most of the Hunters.

Rant of the day over.

JA

Apologies for double posting.

Edited By JA on 21/12/2020 20:15:36

[Andy StopfordParticipant @andystopford50521]

The Nazis had a curious infatuation with wacky super-advanced gadgets, see all the projects for advanced aircraft, jet aircraft (often multiple designs to do the same job), ultra complicated engines, radio control, even flying saucers for goodness' sake.

Most of these weren't even wanted by the services who were going to use them, and never got beyond the prototype stage, but they represented an ongoing drain on resources.

It's said (haven't got a ref to hand, but its an oft-repeated view) that the expenditure on the V-Weapons was comparable with the Manhattan Project, but it was too late to do anything to significantly affect the outcome, and strangely there was little enthusiasm for building the device to put on the top of the V2 which would turn it into a real game-changer. Dodgy Jewish science and all that.

Although the Allies had their share of wacky ideas, they were kept under control, so that the vast majority of design and production resources were devoted to churning out effective, good-enough designs. As Stalin said, "Quantity has a quality all of its own"

As for the reason for this blindspot, it might be down to romantic delusions of 1000-year Reichs bristling with Wagnerian weapons, but another factor might have been that they didn't have a formal system of reserved occupations, so that if you were a geeky, techy youngster you had a very real prospect of being sent to the Russian Front, no matter how good your abilities at science/engineering, etc, and no matter how lamentably un-military your character.

So the reason for some of this stuff may well have been down to kindly departmental heads putting in a good word to the authorities about young Hans' flying saucer ideas and saving him from a pointless fate at Stalingrad.

[JAParticipant @ja]

Thanks Andy, agreed.

JA

edit: It is worth seeing what Britain offered the USA under Lend-Lease.

Edited By JA on 21/12/2020 21:54:02

[Ex contributorParticipant @mgnbuk]

It is remarkable that the German jet engines has flight times measured in hours, but there are Meteors and Vampires still flying today.

But nobody manufactures centrifugal engines any more – a stepping stone that got around some early difficulties, but ultimately a technological dead end ? But still useful to Martin Baker for low level testing of ejector seats in a modified Meteor due to their better resistance to birdstrikes.

I'm pretty sure the German designers / engineers would have been aware of the shortcomings of their engines and, had the materials been available (nickel, chrome, other exotic metals) in suitable quantities, worked to rectify them. But, under the circumstances, better to have a short life engine than non at all ?

Possibly for the best that the Germans had such a chaotic system for weapons design, procurement & testing that wasted resources and delayed development. The rigid requirement for dive bombing capability on the He177 being one that effectively denied the Luftwaffe a strategic bomber. Yet they still managed to get the first guided missles, cruise missiles, intercontinental ballistic missiles etc. into (limited) service & their development work on ground to air and air to air missiles apparently formed the backbone of the development of these systems in the Cold War – on both sides.

The technological transformation in the mid-30s to mid-40s is an interesting period to study – with the benefit of several decades distance. So much change in such a short timeframe – from front line biplanes to jets in less than 10 years.

Nigel B.

[JAParticipant @ja]

Posted by mgnbuk on 22/12/2020 07:55:34:

But nobody manufactures centrifugal engines any more – a stepping stone that got around some early difficulties, but ultimately a technological dead end ? But still useful to Martin Baker for low level testing of ejector seats in a modified Meteor due to their better resistance to birdstrikes.

Nigel B.

Almost all helicopter gas turbine engines use centrifical compressors. They are still very much around in small engines and are very much not a technological dead end.

It is worth thinking what the Allies managed to develop during the war: Centimetre radar, DDT (OK it had serious environmental problems), antibiotics for a start.

JA

[Martin ConnellyParticipant @martinconnelly55370]

The talk of engine life in hours makes it sound as though that was a historical fact and only applicable to old engines. The Adour engine used to power Hawks, as used by the Red Arrows for example, had an identification plate and 10 modules (one was the gearbox and pumps pack that went on the outside). The other 9 modules were stacked to form the engine. I spent some time in an RAF engine bay working on them and we often built up an engine with single digit hours of remaining life on a module. The engine was then tested, put into an aircraft, run for a small number of hours and removed to be stripped down to change the module out.

Martin C

[Cornish JackParticipant @cornishjack]

The following may be of more interest to Andrew, but for anyone interested in fliying, unpowered or powered, there are lessons to be learned.

Two people owe their continued existence to the (lack of) height of a geographical feature and the stress capacity of a set of wings!!!

**LINK**

Festive wishes

Bill

[SamsarandaParticipant @samsaranda]

Martin C

Re: the adour engine fitted in the Hawk, I inspected many of them in situ, there was a problem with the trailing edge of second stage compressor blades cracking, which could lead to disastrous consequences if not detected in time. We used to inspect the engines at I think every 20 flying hours if my memory serves me right. The only way to inspect the engines while fitted in the aircraft was to be fed down the engine intake with your eddy current equipment to test the blades. If you ever see a picture of a Hawk aircraft just look at the size of the engine intakes, they are not very big, safe to say that I was a lot thinner in those days, the early 80’s, and lying prone with your arms over your head inspecting the blade trailing edges, in the dark, and if your unlucky the aircraft has not long landed so you have the heat coming from the engine, not the best sauna I have had. Just one of the interesting jobs that came my way during my 22 years in the Air Force.
Dave W

[Martin ConnellyParticipant @martinconnelly55370]

I did spend about a year on the Hawk line at Brawdy.

Martin C

[SamsarandaParticipant @samsaranda]

Martin C

My time on Hawks was at Chivenor but also worked on Hunters at Brawdy, I was NDT at the time.
Dave W

[Andy StopfordParticipant @andystopford50521]

Posted by JA on 21/12/2020 21:50:14:

Thanks Andy, agreed.

JA

edit: It is worth seeing what Britain offered the USA under Lend-Lease.

Edited By JA on 21/12/2020 21:54:02

Interesting. I didn't know about Reverse Lend-Lease, I suppose I always had some vague assumption the Americans just paid for the British stuff they used.

re. the glider into IMC video – wow, sobering stuff. For those interested as to how they got themselves into this situation, there's an analysis here:

[Michael GilliganParticipant @michaelgilligan61133]

Another interesting bit of history : **LINK**

https://www.nationalgeographic.com/history/2021/01/remembering-night-two-atomic-bombs-dropped-on-north-carolina/

MichaelG.

[Author]

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