Soviet jet engines of the past...

[Lucky13]

I keep hearing and reading, that Soviet jet engine designs was lagging behind the west, why was that, why did it take so long for them to get that intercontinental jetbomber, in this case the Tu-160, for which they tried to build since '50's?
What was it that made M-4 Bison, Tu-16 Badger, Tu-22 Blinder have such unsatisfactory fuel economy etc., etc?
Was it the material, engine or the whole design itself?

 

[MiTasol]

I keep hearing and reading, that Soviet jet engine designs was lagging behind the west, why was that, why did it take so long for them to get that intercontinental jetbomber, in this case the Tu-160, for which they tried to build since '50's?
What was it that made M-4 Bison, Tu-16 Badger, Tu-22 Blinder have such unsatisfactory fuel economy etc., etc?
Was it the material, engine or the whole design itself?

My suspicion is that the Soviets lagged for so long because they had no turbocharger technology.

This may sound a strange reason but, if you look at the development of the jet in the US and the UK, turbocharger technology was the crucial factor in the rapid catch-up and development of jet aircraft by the USA.

Whittle started design and production in 1930 with no government, and very little industry, support.

The British government started funding the Whittle engine in 1937, only after Whittle actually had a running engine, but the Brits did not get their first jet aircraft into the air for four years, May 41.

The US government did not start funding jet engine development until mid September 41 and the US had their first jet aircraft flying just 12 months later.

Much of the credit for the rapid manufacture and development of the jet engine in the US belongs to Sanford Moss at GE.

As a student at Cornell, Moss wrote his PHD thesis on the theory and design of gas turbine engines. His concept from day one was a turboshaft engine for producing electricity.

He ran his first gas turbine engine before WWI but it did not produce any useable power - and no he was not the first to run a gas turbine – that honour goes to Frenchman Armengaud Lemale in 1906, who also wanted a turboshaft for electrical power.

The Moss thesis attracted interest at GE and that got him a job with them where Moss first concentrated on centrifugal compressors used in blast furnaces and on steam turbine development. The experience he gained in these fields resulted the National Advisory Committee for Aeronautics asking him early in WWI to find a way to give military planes more power. Moss's solution was the turbocharger.

Part of his test rig was a flame tube/combustion chamber that took his compressed air and heated it to produce the required high temperatures for testing the turbine. When people suggested that the output could be used to produce power his response was basically "been there, done that, forget it".

In the period between World War I and World War II Moss also developed the geared supercharger using design principles that have since been followed on most aircraft engines.

Although 65 at the time, he returned to GE at the outbreak of World War II and went to work refining the turbocharger.

When the US got the Whittle plans under reverse Lend-lease Moss was given the task of producing the engines. Given his experience on turbochargers he had no problems with materials or with designing the tooling and processes to produce the Whittle engine and quickly recognized how to make improvements to it.

In 1845 the Soviets on the other hand were basically in the same position Whittle was in 1930. No industry manufacturing aircraft turbochargers or the materials and tooling required, and little knowledge of the aerodynamics involved.

What knowledge they did have mainly came from old technology centrifugal flow Rolls Royce Nene engines they purchased.

To quote Wikipedia "The Soviet aviation minister Mikhail Khrunichev and aircraft designer A. S. Yakovlev suggested to Premier Joseph Stalin that the USSR buy the conservative but fully developed Nene engines from Rolls-Royce for the clandestine purpose copying them in a minimum of time. Somewhat logically, Stalin is said to have replied, "What fool will sell us his secrets?"
However, he gave his consent to the proposal and Mikoyan, engine designer Vladimir Klimov, and others travelled to the United Kingdom to request the engines. To Stalin's amazement, the British Labour government and its Minister of Trade, Sir Stafford Cripps, were perfectly willing to provide technical information and a license to manufacture the Rolls-Royce Nene. Sample engines were purchased and delivered with blueprints. Following evaluation and adaptation to Russian conditions, the windfall technology was tooled for mass-production as the Klimov RD-45."

Klimov then developed the RD-45 into the VK-1, which differed from the Nene in having larger combustion chambers, a larger turbine and about 15% greater airflow through the engine while still fitting inside the same fuselage.

This resulted a far more reliable engine with greater thrust than the Nene. Having worked on both I definitely prefer the VK-1 because attention has been paid to getting standard tools on nuts, bolts and fittings. Like the MiG 15 it was designed to be maintained by conscripted tractor mechanics with the minimum use of special tools. The turbine blades at 2000hrs still look like new whereas the Nene ones definitely look worse for wear by just 300 hours.

From the MiG engines the next step the Soviets had was to design an axial flow engine probably using a mixture of captured German WW2 technology and Nene technology - aerodynamically not a small step.

As for fuel consumption - I have no idea and cannot remember the fuel burn on the MiG and Canadair T-33. I do remember that the MiG-15 range is dramatically affected by altitude though.

I also wonder how much of the information on the Soviet engines is propaganda. Certainly if you look at many "authoritative" sources (like the Flight Magazine cutaways) you will see that the MiG-15 has a one piece fuselage and wing. The reality is the wings come off virtually flush with the side of the fuselage and are held on with just four bolts each side (not 100 odd like the Sabre) and its flight controls are almost purely aerodynamic - not irreversible hydraulics with no manual reversion like the Sabre.

Hopefully many others will add their thoughts both for and against my suppositions.

Mi

 

[nuuumannn]

The Rolls-Royce Heritage trust has produced a superb little book titled Early Russian Jet Engines; the Nene and Derwent in the Soviet Union and the evolution of the VK-1 by Vladimir Kotelnikov and Tony Buttler. Worth getting your hands on as it gives good info on the first Russian jet engines.

The Rolls-Royce Heritage Trust: Early Russian Jet Engines

 

[MiTasol]

Thanks Nuuuumannn

Mine is ordered - the RRHT site has several other good books so is worth looking at for other items - for me 'Rolls-Royce Hillington - Portrait of a Shadow Factory' by Peter Sherrard is a must have

Mi

 

[kool kitty89]

The Russians had lots of pre-war gas turbine development going on and many, many attempts at mating their turbochargers to aircraft engines, but had continual troubles apparently mostly due to manufacturing and industry technology limitations in the USSR. (both in terms of metallurgy and mechanical engineering, they had a lot of good engineers capable of working with things in theory, but had to make many more compromises when executing them in practice)

This was worse than the German situation with material shortages (and skilled labor shortages) due to their industry having more advanced manufacturing techniques (including alloy production -including higher quality alloys of similar metal composition, but also things like bearings, among other things) and thus could use smart engineering compromises more effectively in practice.

Russian engineers also had issues with being relocated to the Urals early war and delaying most of their work substantially, this included Lyulka's turbojet work. (though their abandoning of the 2-stage centrifugal design in favor of an axial one later on probably didn't help matters either, at least as far as getting into reliable production)

Of course, then there's Stalan's purges and inspections and incarceration of some of the more potent talent in the industry. (and in some cases, still exploiting that talent from work camps ... but any engineering achievements done there would obviously be of questionable quality compared to proper working conditions -and motivation) This all, of course, being hardly limited to gas turbine design.


The Soviets did appear to manage reasonable reliability in manufacturing their BMW 003 and Jumo 004 copies, albeit apparently without the up-rated/refined models entering production at the end of the war, or about to. (Jumo 004D and E should have performed better, at least) Though may have made other changes like replacing some mild steel components with stainless steel. (I haven't seen solid evidence either way, but lots of supposition on the post-war copies at least having much longer service lives/time between overhaul than the war-time 004B -the 003 already managed very good TBO with its mild steel combustion chamber, and also already featured overrev capability for emergency power as implemented with the He 162)


As far as native Jet engine development went in Russia, there was also the issue of only have one major engineering effort both pre war and into the late 1940s with Lyulka. Though they probably would have relied more on those designs, particularly the refined version of the TR-1, had it not been for reverse engineering Rolls Royce's designs. The TR-1 had relatively poor fuel consumption and thrust to weight ratio, but still better than the copied German designs by a significant margin while also being more powerful through sheer size (roughly in the size/weight/performance range the HeS 011 had been intended for, incedentally, though better than that engine ever actually reached in testing, and a simpler all-axial design at that). Reliability was initially an issue, but that seems to have been addressed with later refinement while the lacking thrust to weight ratio and fuel consumption were the real reasons it was abandoned over the RD-500 and VK-1. (of course the initial RD-45 had its own reliability problems anyway)

Without access to the Nene and Derwent V, I think it's reasonable to assume Soviet designs would have pressed on with twin-engine fighters oriented around the TR-1 given it was still their best option available. The designs built around the Derwent/RD-500 might have attempted single engine TR-1 configurations, at least once reliability was good enough, but I'd think twin RD-20 powerplants would make more sense there, like the MiG-9 used -003 copies-, leaving the RD-10 (004 copies) the odd ones out and not really fitting into a useful gap between the TR-1 and RD-20. (particularly assuming the RD-20 achieved similar higher reliability and serviceability advantages to the german counterparts, and 2 RD-20s had similar thrust and lower frontal area to a Derwent V though double the weight and about 30% higher fuel consumption)

Another option for a MiG-15 sized/powered aircraft would be three RD-20s (still lower frontal area than a Nene, and slightly higher thrust, or substantially higher with overrev, higher than a pair of TR-1s actually), but of course weight and specific fuel consumption would be higher. (good low-drag airframe design taking advantage of the smaller area and optimizing the placement of the 3 engines to maximize that might have compensated for the fuel consumption issue, plus keeping the intake and exhaust length short would improve thrust losses and real-world specific fuel consumption, more like the MiG 9's engine arrangement and less like the MiG 15 or F-80/84/86)

On that RD-20 thought, those smaller, lighter, slimmer (probably more reliable) engines probably would have fit the Su-9 better than the RD-10 did, particularly given its smaller size and wing area than the Me 262. (top speed may not have improved, given the reduced thrust, but the lower drag and weight should have helped handling, stall speed -and consequently take-off and landing performance, range, and possibly rate of climb) If the RD-20 could overrev like the 003E could, take-off and emergency top-speed would have improved even more. (plus with those engines it would have looked a little less like a Me 262 and been less easily stigmatized politically as the Su-9 supposedly was)