TR Propulsion Systems

Yasar_TR

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Transmission is more critical than the engine, but still big!
S&T Dynamics’ automatic transmission failed in the durability tests six times for the K2 Tank.
A tank transmission must run for 320 hours without defects.
I'm more conservative, but lets see..
This issue was discussed here and the situation of Korean transmission was explained by @Baljak in detail. Just do an “Altay Transmission- Baljak” search and you will see the explanation.
According to @Baljak this was most probably a defective part that needed to be redesigned and remanufactured. And that this is now done. So the new transmission should work.
Apparently according to @Baljak , the MTU engine is a short stroke engine and the Doosan engine is a long stroke engine and has higher torque at lower revs. This introduces unforeseen stresses on the transmission. That may have been the underlying problem in the transmission coupled to a part‘s design defect.
 

Rodeo

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I have no clue as to what is outdated, perhaps you could give a detailed response to which I {or any other mod) can act upon and update as you've requested.
TTZA - 400hp
AZRA - 600hp
UTKU - 1000hp

These are the correct power outputs now.
 

Rodeo

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Tidbits from the video:
- TS1400 reached 1572 SHP in Jan 2022
- The 10.000th Blisk delivered for LEAP engines.
- PD222 reached 225hp power (test footage at 1:00)
 
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DBdev

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So GE pockets %46 of the TEI's profits but doesn't help with CAATSA and other US senate secret embargos? What a great partner.
 

RadarGudumluMuhimmat

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Despite CAATSA your collaboration not only with GE but with other American companies is still going on, what else do u need.
What do commercial products have to do with CAATSA? If the bilateral trade volume with America is not as it should be, who can guarantee that the merchant ships will not pass through the straits with a delay of 3 months?
 

Merzifonlu

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The road to the top of the mountain passes through the slopes of the mountain. Let's first design and manufacture the "ordinary" 5th generation engine that can produce 35.000 lb thrust.

On the other hand, IMHO he is right in the long run. Variable by-pass engines provide significant fuel savings.
 

Yasar_TR

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A turbojet engine is most efficient in higher altitudes where air is rarified. All the air sucked in through the fans in to the compression section, after helping burn the fuel in combustion chamber, is exhausted from the nozzle creating jet thrust. 100% of the thrust is generated by the air going through the engine.

A Turbofan jet engine works well and efficiently when there is dense air it can propel through the fan system to help develop more thrust. The air that goes through a low bypass fighter jet engine core, constitutes around 90 to 93% of the thrust. The rest of the thrust is provided by the cooler air sucked in by the fans and going around the engine.

At lower altitudes you need more of this cool-air thrust. At higher altitudes you need less of it and mainly the thrust generated by the engine core is needed.

By opening and closing the bypass ducts according to the outside air density you can give optimum maximum thrust at all altitudes. The engine that can achieve this is called a variable bypass or variable cycle engine.

GE is developing such an engine (XA100) for the F35. Tempest engine will be of the same tech.

1672058004485.png

When the valves are closed it is just a turbojet. When they are open then a turbofan.
 

Nilgiri

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Earlier post I made on the underlying issue:

Especially this part:

His implying ~1:1 bypass ratio for TF-6000 illustrates the MIUS basically will balance supersonic capability with payload/range/endurance curves as best as theoretically possible. Since going above this will make supersonic impossible and going well below it (and having lower bypass realm) will reduce the mass and payload efficiency of the platform.


and this earlier one:

Military turbofans that go supersonic also have to follow this constraint and are essentially fan augmented turbojets. There is more design expectation for such aircraft to perform in the subsonic realm (compared to say a concorde) so having/balancing as much as bypass as possible is a good advantage since you have more effective range/time that way.

But generally cannot go much above a bypass ratio of 1:1 if you want to have supersonic capability (you start to invest too much in the fan side of things and impose penalties on the core relative to the mission/design profile of the aircraft). i.e To better provide for supersonic capability at larger engine thrusts, simply the bypass ratio is often kept in 0.5 - 0.8 design range so as to not impose on having larger afterburner or having complex intake systems for the engine itself.


Essentially (variable cycle) allows engines of much higher bypass than 1:1 to go supersonic by the (flow management, ducting etc during specific regimes) summary that yasar gave a few posts above.

For commercial turbofans large scale market economics, supersonic is just not important at all compared to total thrust...so high bypass engines are name of the game (and they are impossible to go supersonic as result, given they gear towards moving large amount of air more slowly to develop their total thrust, whereas supersonic needs the bulk of the air to be supersonic i.e more core-based).

Where you have tradeoff is for aircraft that will have to operate in all regimes (subsonic, transonic, supersonic) and obviously fighter aircraft are in this realm.

More bypass is advantageous for efficiency at subsonic travel which the fighter aircraft overall spends most of its mission time life on (amount of time you can spend in air with same fuel onboard as more thrust is simply from the fan rather than core, which essentially "gears" the thrust more optimally), just like a higher gear setting available for car (say Overdrive or 5th compared to having just 4th and the lower gears).

Many other matters are also improved (engine cooling, long term performance and health and so on) by higher bypass thrust compared to something closer to a turbojet...given the problems of making large turbojets (as the Soviets especially would find out but were stuck with).

i.e The engine onboard a fighter plane starts to dip into all the advantages high bypass engines in commercial sector enjoy etc....but retains (more turbojet like) supersonic capability at same time.

The historic comparison of note here would be the US approach of developing essentially a related concept of variable cycle for the Blackbird (in that the turbojet was able to switch to something closer to a ramjet at higher speed regime) and compare that with the approach the Soviets took with the Mig-25 (just making a turbojet bigger).

The latter was "easier" route development wise but was baked in with serious problems as well...showing the dividends of having variable cycle even back then.


There are however a myriad of design challenges with variable cycle (it remains a frontier RnD area) compared to traditional "fixed cycle" gas turbines.

It is still early days in addressing them more optimally with the research we have progressed into in the last few decades.

That's why they are only likely to be somewhat mature for introduction in 6th Gen warplanes/drones onwards.
 
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Nilgiri

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This was the main post I made on MIUS thread about how traditional "fixed cycle/bypass" works:


SFC is most directly correlated to bypass ratio (which is also correlated to engine diameter by way of needing larger fan as you grow it).

Bypass ratio is by far the largest factor in increasing thrust of a jet engine efficiently since you are "gearing" air to move in larger volume at slower speed rather than vice versa (i.e smaller volume at higher speeds ....which uses far more energy to do, but is only option to increase thrust when you have zero bypass like in a turbojet, which is why turbojets have higher SFCs in comparison generally).

However if you want the engine to go supersonic (and have some range of supersonic past just mach 1), the bypass ratio can only be increased to a point as the effective jet exit velocity has to also be that supersonic velocity (and fans cannot produce supersonic air, as it is detrimental to have their blade tip speeds operate past supersonic which is a longer conversation to get into).

This is exactly why the concorde used turbojets (with no bypass) for example....as there was little to no design expectation for the aircraft to perform in subsonic role and harness any efficiency from that range of speed where a fan would be useful.

Military turbofans that go supersonic also have to follow this constraint and are essentially fan augmented turbojets. There is more design expectation for such aircraft to perform in the subsonic realm (compared to say a concorde) so having/balancing as much as bypass as possible is a good advantage since you have more effective range/time that way.

But generally cannot go much above a bypass ratio of 1:1 if you want to have supersonic capability (you start to invest too much in the fan side of things and impose penalties on the core relative to the mission/design profile of the aircraft). i.e To better provide for supersonic capability at larger engine thrusts, simply the bypass ratio is often kept in 0.5 - 0.8 design range so as to not impose on having larger afterburner or having complex intake systems for the engine itself.

To answer your query at the end, this generally results in military turbofans (be it for trainer size or TF-X size) being bounded to SFC of 0.6 - 1.0 , and that will be where Turkiye's future military turbofans (i.e those that intend to have supersonic capability) will also generally be....depending on their respective design profile balance.

Pushing below 0.6 (i.e growing the bypass ratio more) comes with consequences where the engine (given its resulting size and thrust) becomes more akin to one used for a supersonic bomber rather than a fighter etc when it comes to military use..... or for civilian use the first range of turbofans that can be used in business jets and generally smaller civil aircraft.

Pushing it even lower (than say 0.5, 0.4, 0.3 etc) needs drastically larger bypass ratios and you enter the realm of (fully subsonic) cargo aircraft and civilian aircraft.

Turbofan concept naturally orients (its growth by larger and larger bypass ratio and fan diameter) to subsonic use and using the larger thrust to simply propel larger aircraft (rather than using thrust to propel faster supersonic aircraft where you need to make the turbojet design/aspect better).

Turbojet concept naturally orients itself to supersonic use in comparison.... hence we have essentially a hybrid of the two concepts in (supersonic capable) military turbofans.

A variable cycle engine would essentially permit the SFC (specific fuel consumption) to reduce to below 0.6 while retaining supersonic capability....rather than current situation where supersonic capability (especially on a fighter aircraft size) essentially stops quickly below this number. i.e the 2nd half of that post.
 
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