Team Tempest Future Fighter from the UK

Since this thread appears to be otherwise dead, I’ll dare to continue the variable cycle discussion.

Feel free to check. for Kaveri

“Kaveri engine has been specifically designed for Indian environment. The engine is a variable cycle-flat-rated engine in which the thrust drop due to high ambient, forward speed is well compensated by the increased turbine entry temperature at the spool Kabini altitude test speed. This concept has been already demonstrated with high temperature and pressure condition in DRDO’s High Mach Facility. Kaveri engine is controlled by Kaveri full authority digital control unit {KADECU), which has been developed and successfully demonstrated at DRDO’s test bed.”

https://www.drdo.gov.in/drdo/pub/tec…000/Kaveri.htm

As i’m no expert in engines and technical english is a bit hard to me, i’ll give you a link about M53. Feel free to explain me

http://www.institut-strategie.fr/Moteurs_10.htm

Well, let’s say the bypass ratio variation from the wider speed/altitude envelope is 1.5x greater on the M53 than the CFM56 – i.e. we only consider the altitude effect because it has variable inlets to take care of Mach number. In the CFM, we have a 12% BPR fluctuation, so a very crude estimate for the M53 (without accounting for the adjustable mixer) comes to 18%. A 0.32 to 0.4 difference is actually a 20% range, so the supposed variable cycle technology may well be responsible for a mere tenth of the bypass ratio variation. And that assumes the surge characteristics of the M53 fan even accommodate a mixer area schedule which optimizes fuel consumption. For all we know, its primary function of maintaining stable flow forces it to close down at operating conditions where for best efficiency it should really open up (or vice versa). BTW, a similar solution (rather blandly called the “Variable Area Nozzle”) was prepared by P&W for the bypass stream on PW1000G geared turbofan due to its low pressure ratio fan – it turned out to have adequate stability margins with a fixed bypass nozzle though.

As for the links you supplied, the French author is unequivocally wrong on the claim that the M53 is the first ever variable cycle engine to enter service (that honour belongs to the J58, as mentioned), so what makes you think his assertion on it being a VCE at all is any less hyperbolic? People make preposterous exaggerations occasionally – it’s a fact of life. In the case of Kaveri, the English used on that page is pretty tortuous and other technical terms are used incorrectly as well (for example “pressure Combustion Chamber Liner ratio”, whatever that’s supposed to mean). The author may be refering to something entirely different from the accepted sense of variable cycle, for example “dual mode” as in dry/reheated.

Another thought on variable cycle engines – the STOVL F135 can most certainly be thought of as one. In cruise mode its BPR is about 0.6, but in powered lift configuration with the shaft-driven fan engaged (where it essentially becomes a geared turbofan like the PW1000G) it will be well above that – not sure how high, but I’d guess comfortably more than 3.0. Unlike what may be the “conventional” idea of variable cycle it’s a binary thing here (there are two distinct modes without smooth variation), but the BPR range is bound to be extremely wide.

What is the need for a more refined mock-up? Your not one of these people who judges the weight of a programme by the quality of the perspex used in the mock-up are you?

Curvature Group. https://www.instagram.com/p/BnRwReoHmWF/?utm_source=ig_share_sheet&igshid=19u8s9tg8jsap
Let’s hope the second mock-up is a little bit more refined.

The company that produced the Tempest mockup have now completed some revisions to it and the second mockup that has been made.

Which company made the mockup?

Yes, but no demo…

Will be that during the Belgian Air force days on the next w.e? The F-35 will be there too.

The company that produced the Tempest mockup have now completed some revisions to it and the second mockup that has been made. They will be used in a global tour of defence exhibitions and air shows (etc) over the next couple of years.

First stop Belgium.

This according to an Instagram post on their site.

Sorry.

More related. FT not so optimistic about Tempest program…

https://www.ft.com/content/a83265d0-b045-11e8-99ca-68cf89602132

Verging on thread drift here…

Kaveri? I doubt it.

Feel free to check. for Kaveri

“Kaveri engine has been specifically designed for Indian environment. The engine is a variable cycle-flat-rated engine in which the thrust drop due to high ambient, forward speed is well compensated by the increased turbine entry temperature at the spool Kabini altitude test speed. This concept has been already demonstrated with high temperature and pressure condition in DRDO’s High Mach Facility. Kaveri engine is controlled by Kaveri full authority digital control unit {KADECU), which has been developed and successfully demonstrated at DRDO’s test bed.”

https://www.drdo.gov.in/drdo/pub/techfocus/aug2000/Kaveri.htm

As i’m no expert in engines and technical english is a bit hard to me, i’ll give you a link about M53. Feel free to explain me

http://www.institut-strategie.fr/Moteurs_10.htm

[QUOTE] If the ATAR family is associated with the first generations of French jets and in particular the Mirage III, IV, the M53 is the engine of the Mirage 2000. However, originally it was not intended for such versatile aircraft which explains as we will see, its original and unique formula.

At the end of the 1960s, a new concept of twin-engine aircraft emerged with the idea of having to intercept supersonic transport aircraft such as the Concorde, the Tu 144 and bombers of similar performance (B1).

Snecma was therefore starting to study a new engine capable of reaching Mach 3 – 3.2, or more, by combining it with a ramjet.

Such an engine had to have a low compression ratio (<10) to avoid high compressor outlet temperatures.

This was not advantageous for low subsonic standby and partial thrust regimes, hence the idea of incorporating a limited double flow effect which also provided the benefit of cold air to ventilate the PC channel.

With a compression ratio of 10, there is no need for a double-body compressor and no need for variable displacement: a simple and economical solution. Thus was born the monocorps double flux formula of M53.

The Mach maxi requirements quickly fell back but the original M53 formula remained attractive for M = 2.2 – 2.5 by its simplicity. The reduction of the Mach made it possible to switch to an almost all-titanium engine and, of course, eliminated the cooling system for the turbine cooling air.

The M53 was intended to replace the ATAR 9K50 in the Mirage F1 single-engine “Market of the Century” then, this one having been won by the F16, the M53 was finally retained to motorize the Mirage 2000 launched in 1975.

It should be noted that the M53 was originally intended for twin-engine aircraft. The switch to the Mirage 2000 single-engine application led to two studies: an increase in thrust by changing the CoBP and the introduction of a largely analogue full authority redundant electronic regulation associated with hydromechanical back-up. This regulation gives the pilot an engine with no limiting instructions in the entire flight domain: as is the rule for Snecma engines.

The Mirage 2000’s versatility requirements have also led to one of the M53’s most original features: the variable section secondary flow regulator, which makes the M53 the first variable cycle engine ever put into service.

This system makes it possible to introduce variability in the dilution rate. When closed, it increases the engine’s specific thrust at maximum speed, especially in supersonic conditions. Open, it favours an optimisation of the Cs at partial low altitude cruising or standby speeds.

Translated with www.DeepL.com/Translator[/QUOTE]

Pg. 39 – http://www.barringer1.com/pdf/ASME-Dec-2013.pdf

BTW Hallow – ADVENT is NOT an ENGINE.

Anyone noticed that ADVENT is NOT the first variable flow engine? Old M53 and indian Kaveri are…

J58.

Kaveri? I doubt it. And the M53 is not really a variable cycle engine either. It has an adjustable bypass/core exhaust mixer area, but that’s a transient stability measure for the fan. Because of the unique single shaft configuration with the LP & HP compressor rotating at the same speed, it needs a means of regulating fan back pressure to maintain adequate surge margin in some operating conditions. All in all, the range of variation in BPR is what, from 0.32 to 0.4, IIRC? Too small to make a significant impact in fuel consumption.

Consider also that a common or garden variety CFM56 will have its BPR fluctuate between about 5.2 and 5.9 over the course of a typical airline flight, solely due to changes in speed, altitude and power setting. As a percentage that is a narrower range than on the M53, but the latter also has a *much* wider Mach/altitude envelope (~3:1 ratio in terms of speed, ~1.5:1 with respect to altitude between M2000 & A320). I would not be surprised if the vast majority of the 0.08 bypass ratio variation in the M53 is simply down to that, rather than the adjustable area mixer!

Anyone noticed that ADVENT is NOT the first variable flow engine? Old M53 and indian Kaveri are…

Obviously BiO.

At the highest classification level the norm is to require US citizenship to be part of these projects unless of course the OEM can demonstrate absolute need. You (engineering working on such a project) are then personally liable for divulging thigs that are protected even if it is to a parent entity outside the US. You can’t really stack a classified project by folks who work for your foreign entity in the hope that the US government will fund some nice S&T/R&D expereince and have them go back and apply it on those projects. Again, as I said these things are protected based on both mutual trust and laws and regulations.

@BiO: we don’t know for sure if those “ppl” were British citizen brought in the US because of their assigned prior work or from the US. In the first case they would be legally allowed to continue their work initiated prior to their US assignment given that they both fulfill their confidentiality clauses and the IP rights they would re-use. If bound by some kind of NDA that make them unable to work on similar project afterward, those ppl would have to be compensated, which often means that there will still be on the payroll of the same entity in the US. Hence the speculations stop here. So IMOHO, in every case If there is a subject its because there is a project, no matter if that is under case a or b.

But none of that takes away from the fact that Rolls Royce still has a lot of people who are now knowledgeable of the thermodynamics, fluid dynamics, and such of a three stream process. And, no, there is nothing that prevents those people from using that knowledge elsewhere.

Mobility of knowlege is indirectly protected by making individuals liable for their conduct if they have been involved with sensitive or classified US programs. If an ADVENT team member from the RR NA team goes to work in the UK on an adaptive engine program, he will surely come under scruitiny too see he is not sharing technology and knowhow that is protected. RR North America for the purpose of the US DOD is a US entity and therefore any exchange of human capital to non US entititles will involve complex regulations that are set to prevent flow of protected work and knowledge unless excplictly sanctioned.

Same with BAE…they can go ahead and hire Lockheed’s top stealth guy if they pay him/her enough but they can’t then ask the person to go to work for the parent entity abroad on a project that would require the same set of expertise without coming under scruitiny. As I said, doing this systematically is not the main intention of seeking direct investment in US strategic sectors. The reason is marketshare and profit.

Of course RR has people in Europe who are knowledable in fields you mentioned.

Also, because I’m kind of tired of repeating this, here’s a couple examples of their continuing work on distortion tolerant fans – a key component of an adaptive cycle engine because you are intentionally inducing some distortion by suing the third stream.

https://www.ainonline.com/aviation-news/defense/2009-06-15/rolls-royce-research-ucav-powerplant

https://www.stratpost.com/rolls-royce-debuts-new-advanced-military-fan-at-aero-india-2015/

You can’t place limits on knowledge. That’s why they are soldiering on.

@Sintra:
No. It started with an underlying competitive process to power the UCAS that was then finalized by an agreement to put an M-88 core into the then combined Fr-UK proposed solution. This means only that whatever the Brits had in mind was modulable enough to be scaled and paired to a foreign design (foreign as non-integrated). Once again this reflect the above underlined points.

B/w someone wrote this at the time:

The timeline is spot on. Decade and a half is precisely the expected timeframe for delivering hardware (whatever hardware FCAS becomes), on top of that, one of the biggest players in every major “Pentagon Jet war” for the last decade has been Rolls Royce Liberty Works, and while i dont have doubts that there are restrictions between RR North America and RR Uk, i would be more than a bit surprised that a great part of the development work done by Liberty Works in things like the F136/ADVENT/etc wouldnt cross fertilise the UK future programs (pretty much what P&W and Snecma did three decades ago with the likes of the TF30/TF306/M53).

Cheers

…

We’re discussing two completely different things, bring-it-on. I’ve already said that if they are contractually bound (and, like you said, they likely are) then all of the hardware, design software, and recorded data, measurements, simulations, and such cannot be used. But none of that takes away from the fact that Rolls Royce still has a lot of people who are now knowledgeable of the thermodynamics, fluid dynamics, and such of a three stream process. And, no, there is nothing that prevents those people from using that knowledge elsewhere.

That’s why I said it would set them back a good ways but it doesn’t put them back at the very beginning. They already have a core team who has a pretty good idea how to approach the problem (in new ways). The setback is in having to duplicate/modify what they did before.