I was just curious what the top speed it could achieve at Sea Level was, because I remember hearing it was slower than other jets, but couldn’t recall the exact number. Wasn’t debating engine performance in that comment.
3 Likes
Except I’ve used sources and shown them here for everyone to see, but the sources he uses to backup are conveniently restricted, and from the ones I can find on Google none of them backup what he is saying. Like I said, he constantly lies and twists sources. I remember when the Gripen was on the dev server, and he was looking for sources to restrict its ability to pull G. He ended up linking a study about the G-regulator for the G-suit trousers the pilots wear…to say that “it seems early Gripens had problems with the G-regulator”. Comical.
edit:
the link for his “source” doesn’t work lol.I can’t remember which one it is from and what the context is.
3 Likes
Maybe the url went recently bad. Have you tried web archive? https://web.archive.org/
Paste the link in there, it may show up
@MiG_23M would you mind replacing the source with a non restricted one or giving us a reliable way of verifying the source other than “can be found in google”?
I think the thrust is about right.
It can be argued that it is using uninstalled thrust but many other planes are also using uninstalled thrust because the FM is tuned accordingly so bit hard of a report to be made without an actual source stating installed thrust in gripen.
Anyways, I dont think the problem of the gripen is the engine thrust curve.
8 Likes
If you want to message me in discord I’ll be more willing to discuss the materials there, of course you are welcome to criticize me for having not provided a source on this particular topic… but I did. The +200 degree improvement is mentioned in the Core II upgrade, which is part of what makes the -402 different from the RM12.
Everything I have provided does…?
In that case, the top speed is less than mach 1.1 at sea level iirc depending on armament. It will be one of the slowest top tiers in regards to top speed being only marginally faster than the F-5E… though it will have better acceleration. The top speed is primarily due to the sudden drop in thrust as the temperature limit is met more so than anything else.
I did share a source that was non-restricted for the +200 degree F increase in the Core II engine upgrade.
I agree, but my entire point is that the RM12 should not produce more thrust than the F404-GE-402. I don’t have any intentions on reporting the thrust on the Gripen (or making any reports at all, as of the moment)… but the discussion is centered around the real life performance of the two motors. It is clear to me, the -402 should have higher peak thrust than the RM12.
@simbadumba Regarding the source; I believe this link isn’t broken.
1 Like
Ignoring real world numbers for a second - I feel like increasing the Gripen thrust at speed and increasing the drag, would give it the same turning performance and speed, whilst eliminating the nuts SEP.
So the basis for you saying the 402 is better across the envelope, except for static thrust, is the 10 degree Fahrenheit difference? You say the 190 can only be used in short bursts, but I’ve not seen you provide any evidence of how short this special combat rating is. Then there is the fact that the RM12 has better airflow and pressure, factors which are going to give it better performance at all speeds, aren’t important?
There is reality and then there is your reality. I’m getting concerned with how little overlap there seems to be.
Would you mind quoting a few examples and giving context on how the references information doesn’t suggest what he is saying? “nothing, everything” is rather vague…
Thanks, it is working through web archive. @slowhandclap what do you think?
Just nerf the MER
The RM12 would reach the temp limit sooner due to the higher pressure ratio, and then drop off. The F-18’s engine would be able to produce higher peak thrust due to this since the temp limit is reached at higher speeds. You could argue that the RM12 produces peak thrust sooner, and then drops off sooner… and that both engines produce the similar or same peak thrust value and I would agree with that. However, to say that the RM12 produces 25%+ thrust over the -400 when the -402 produces at most +20%… is interesting.
We don’t have that information, it could be anything similar to a VMAX profile for the F-15 or just a higher trim rating such as 102%.
I have addressed these already.
Devs did tell users to just submit a report showing the statistical outlier over other top tiers and yet when I asked other tech mods they told me it likely would be closed on grounds that it isn’t utilizing sources… I guess statistical outliers according to the devs are okay for a report but tech mods aren’t on the same page?
Start by testing this for example:
https://community.gaijin.net/issues/p/warthunder/i/YKhI5oNKuwKG
3 Likes
30 minutes is higher than 50% but it appears to be roughly accurate to what they said they’d fix.
Maybe that aspect of the conversation better belongs in the Gripen thread, though.
30 minutes is full tank
50% is 15 minutes
How about you tell me how his sources do prove what he is saying? Here are the facts:
We know the RM-12 has a better static thrust than the 402.
We know it has superior airflow.
We know it has a superior pressure ratio.
We know that GE, the engine manufacturers advertise it as better than the 402:
If the temperature limit was the most important thing for envelope performance as mig23m suggests, why on earth would the manufacturers not include that along with the other engine characteristics on their website? Perhaps it’s because things like cooling have an effect, which was some of the key systems Saab upgraded…
FYI, his source on the Gripen aiming for 10-15% thrust over the 400, was from 1985 lol, well before they had finalised it. Yet he assumes the Swedish engineers didn’t overachieve like the US ones.
Long story short, the RM12 > 402.
1 Like
I’m not arguing for him and i’m not saying hes right, id just like to have context for your opinion so i can better weigh both of your opinions against each other
I argued all of these points. You say superior ratios, what you mean is higher. Higher ratios mean better static uninstalled thrust, but mean that the temperature limit is reached much sooner.
The -402 has superior flow through the core and a higher temperature limit. The peak thrust is shown to be 20% higher than the -400 according to the NSAID reports and the QNEP chart for the -400. What I said is that Saab had planned for 5% growth over the already 15% improvement. It is possible that both engines produce around +20% thrust over the -400, but the -402 does so at mach 1.2.
What we KNOW is that the -402 met the goal… 20% improved thrust at the speeds they were concerned with. What we KNOW is that the Gripen was aiming for improved thrust in the lower right hand corner of the envelope and what the data SUGGESTS is that it would run into the lower temperature limit sooner due to the higher compression of air and lower flow rate through the core.
By the way, the F404-GE-402 has a higher bypass ratio than the RM12 if I’m reading this correctly.
That’s fair enough.
The sources also say that the RM12 had improvements to the cooling system of the core.
If turbine inlet temperature is more important than mass flow and pressure ratio, why do they not include those on their advertisements/specs for the engines?
I don’t think you know the implications of that, otherwise you wouldn’t have said it.
1 Like
They probably don’t want to advertise the exact temperature limitations between the two engines as it will be highly dependent on the aircraft it ends up installed in? I don’t know why they didn’t include every single variable including the number of fan blades and zip ties holding the engine together in their advertisement. Generally, these are done to export to people and they want to advertise the most basic principles that would be determining factor as to which engine is chosen for a platform.
I said it for a reason. The RM12 is 0.31:1 and the -402 is 0.34:1.
Go ahead and explain what that means to you.
Oh. Like whether the plane is going to have one or two engines? Or if the plane is a Gripen or Hornet?
They include the important stuff for comparisons, generally, when making comparisons. If the performance of the 402 was completely unrepresentative of the dynamic thrust performance, it wouldn’t be a very good comparison for GE to put on their website, would it? Or is it a shadow-government scheme to stop people purchasing the “worse” 402 engine, so only Murica have those secretly superior ones?
I’m glad we’re making progress.
A higher bypass ratio means the 402 is sending more airflow to the bypass instead of through the turbine core…This gives better thrust at lower speeds, and worst thrust at higher speeds. It also gives the 402 better fuel economy.
For context, the F414 that powers the superhornet has a bypass ratio of ~0.25.
1 Like