P-42 World record climb to 12km

[jackmckay]

Hi,

I had a little challenge here. Was trying to recreate the P-42 record in climb that was set on March 20, 1987 committed on heavily modified Su-27 flanker and has set the score of roughly 55secs. The weight of the empty aircraft (without fuel and pilot) was 14,100 kg. The engine thrust increased from 12 500 to 13 600 kgf. Some parts removed and replaced by appropriate parts to achieve best starting position.

My setup included civilian Su-27 with total wight (ME calculated) of 17344kg with 1% of unlimited fuel meaning no extra fuel is carried. I was not able to remove pylons as there's no such options plausible in DCS Flanker right now what actually increased wetted/projected area by some 5% rude estimation. What I can do is reduce weight of fuel drastically to emulate weight loss to match the criteria of record plane which can also help to compensate increased thrust done on original test bed by 2.2t(2x1100kgf). For reference Su27 empty weight is set as 16,380kg by external source so the DCS ME(17250kg) difference in ~1 tone is not understood if you take the weight of pilot and accessories that would otherwise be included in weight estimation.

So the result was that it took me more than 2 minutes to reach 12km in comparison to P-42 55secs never reaching supersonic climb as on record breaking plane.

What do you think? Is DCS Flanker under performing?

Flanker Empty Climb.trk

[Wyvern]

no, its accurate. The P-42, had an heavily modified airframe (No Pylons, Shortened Vertical Stabs removed, specific antennas and the OLS removed, modified air intakes and the "Stinger" in the back was also missing.
The drag the plane produced was way lower, compared to what the Su-27S would produce.
You may be able to get the Thrust:Weight ratio to be as close as possible, but aerodynamics still matter a lot.

It is true that you cant remove the pylons and its stupid, as it only requires the same line 8 times in the Plane's lua (one on each pylon).

Once again I put out the request to ED here:
Unencrypt the FC3 planes's lua files.
The Full Fidelity planes, the A-10A and the J-11A are all (unencrypted) in the CoreMods folder, giving people the ability to make amazing mods for those planes.
Sure people could modify their files then, but they already can with a bunch of planes and Integrity Check is there to regulate it.

So please ED, unlock the locked up files for the F-15C, MiG-29s, the Su-25s and the two russian flanker.
Or tell us why they have been locked up.

[jackmckay]

28 minutes ago, Wyvern said:

The drag the plane produced was way lower, compared to what the Su-27S would produce

not that much as i'm concerned. the frontal projection of plane was reduced by roughly 5% even that sounds aggregated by shear area calculation. the wetted surface is degraded by tail boom removal also in 5% range as there's a big difference between effect of nose cone and tail section effect on aerodynamic forces. from one side i'm on 94kg of fuel and i assume P-42 needed at least 2t or 25-30% of fuel needed to reach that altitude in wetted AFB mode. The removed parts are in compliance with "civilian plane" box meaning no guns, no radar etc. which sounds like it has no effect on overall weight but i assume it should. My rude observation the setup 27 on 1% fuel should be like 5-10% close to P-42. The effect in time is 100% difference. Are we missing an engine in su27? If J11 is unencrypted that could be closer match to try P-42.

Edited May 29, 2023 by jackmckay

[Wyvern]

1 minute ago, jackmckay said:

 The removed parts are in compliance with "civilian plane" box meaning no guns, no radar etc. which sounds like it has no effect on overall weight but i assume it should. 

I dont think the game does that, it just removes the ability to load weapons, but it doesnt edit the plane. Check it, you still should be able to lock other planes. 
As far as i understand, If you set an plane to "Civillian" in ME, AI wont engage it and it wont give you points if you shoot it.

Also when talking about the files, you could look at the J-11A, it is identical with the Su-27 Performance wise, but is unencrypted

 

 

[jackmckay]

tnx for the tip. will try on J11. i think it has slightly better engines then Su27 which could come closer match to P-42. Lets see what happens.

Edited May 29, 2023 by jackmckay

[TheFreshPrince]

Look at how the P-42 started. It was held back by bulldozers so it could go full AB on the ground until it powered up to the max and then they let it go. Like a launch control on a car. You can't simulate that, it will cost you some seconds already.

[Wyvern]

i think you can with active pause

 

[HwyStar]

Or just use a really long runway? The time starts when the plane leaves the runway, correct? I'm not sure if DCS has any really long runways like RL.

Consider messing with the air pressure for your session too (QNH)? (lower is faster) If the Reno airport (RNO) is in the Nevada map it has long runways plus is at 4,300 feet elevation. Wink wink, nudge, nudge...

Don't ask me about the Bridge of Death...

Edited May 29, 2023 by HwyStar

[okopanja]

You can get rid of pylons on positions 3 and 8, by placing double racks and dropping them, but this sadly does not change drag. (measured this!)

Pylons are simply modeled in.

[Pavlin_33]

Unless I missed something, we've already concluded (here on forums), that the Flanker is slower to accelerate than a heavier RL Su-30 in that acceleration video, so yes it is underperforming, it's just a question by how much.

Since DCS Su-27 is capable of reaching above M 2.0, I would guess that the rate at which engines produce max thrust is the issue, and not the available thrust it self.

[jackmckay]

13 hours ago, Pavlin_33 said:

we've already concluded (here on forums)

do you have some links pls.

13 hours ago, Pavlin_33 said:

it's just a question by how much.

well i'm just trying to figure out exactly how much of acceleration is degraded. in last try I couldn't even reach 12km at 48deg climb.

btw, i was testing clean 1%f f16 and reached 15km in 75secs(P-42 has this height on 70secs). modding script(crosscountryrace) to get time and log to test most modules i got. This is quite intriguing state here.

J-11A.lua has thrust_sum_ab = 25000 but on wiki(https://en.wikipedia.org/wiki/Shenyang_J-11) its 2x132 kN which is roughly 26400 but dont know which thrust unit is used tbh.

[Ironhand]

3 hours ago, jackmckay said:

…in last try I couldn't even reach 12km at 48deg climb…

Then you are doing something wrong in your climb. And, if I understood you correctly in your first post, you were unable to reach Mach 1+ speeds in the first climb you reported. That’s another suggestion that there is something wrong in your approach. Not saying that there isn’t an issue. Just saying that the difference is probably less that what you’re seeing.

Edited May 30, 2023 by Ironhand

[okopanja]

1 hour ago, jackmckay said:

J-11A.lua has thrust_sum_ab = 25000 but on wiki(https://en.wikipedia.org/wiki/Shenyang_J-11) its 2x132 kN which is roughly 26400 but dont know which thrust unit is used tbh.

Likely kgf, DCS is metric internally.

Needs to be crosschecked...

[TheFreshPrince]

vor 17 Stunden schrieb HwyStar:

Or just use a really long runway? The time starts when the plane leaves the runway, correct? I'm not sure if DCS has any really long runways like RL.

Consider messing with the air pressure for your session too (QNH)? (lower is faster) If the Reno airport (RNO) is in the Nevada map it has long runways plus is at 4,300 feet elevation. Wink wink, nudge, nudge...

Don't ask me about the Bridge of Death...

 

As far as I understand the time starts as soon as the aircraft moves:

https://www.globalsecurity.org/military/world/russia/su-p-42.htm

"At the right moment, the castle uncoupled the cable, freeing the way for the aircraft, movie cameras and stopwatch turned on, and the P-42 made a swift attack on the storm of world records."

 

The active pause thing might do the trick though.

[bies]

P-42 drag reduction was huge compared to Su-27, it didn't resemble Su-27 performance. It was not only missing many elements of the structure, but also has been polished and sealed over the whole surface of the aircraft. No matter what you do you should never be anywhere near P-42 numbers, both drag and weight.

Modifications we know about were:

Engines uprated to 13,600kg/f each for additional ~2100kg/f of thrust
Weight reduced by few tons to 14,100kg
The aircraft was stripped of paint, polished and all drag-producing gaps and joints were sealed to reduced drag
Wing high lift devices keyed to reduce drag
Cut tail boom
Cut vertical stabilizers
Removed vental fins
Removed drag chute and fences
Removed the optical unit of the optical-location station
Removed wingtip launch rails
Air Intakes has been fixed
Keels Reduced in Height
Removed radar and weapon control system
Radar radome was replaced with a lighter metal nosecone

Edited May 30, 2023 by bies

[jackmckay]

2 hours ago, bies said:

Weight reduced by few tons to 14,100kg

this was empty weight without fuel and pilot. should go up by at least 2-3t by adding fuel and pilot. im on advantage here cos on less then 100kg fuel used and in total by DCS around 17t locked. should be close in t/w ratio if RL j11 engine data is used. all that work on polishing was about achieving extra 3% on previous record done by Strike Eagle, i assume ofc. ill try eagle too.

2 hours ago, bies said:

Engines uprated to 13,600kg/f each for additional ~2100kg/f of thrust

that is what J11 is closer to by engine performance so closest thing to p-42 is J11 in RL in matter of wet thrust. it can be tweaked in lua file IF it has any affect.

5 hours ago, Ironhand said:

unable to reach Mach 1+

in default su27/j11 i wasn't able to go above 600kmh. was using 48deg climb as used on mig31 previous attempts and that should be optimal.

i'll need few days to complete the scripting.

some patience pls. i think its gonna be interesting to see the difference.

[okopanja]

34 minutes ago, jackmckay said:

this was empty weight without fuel and pilot. should go up by at least 2-3t by adding fuel and pilot. im on advantage here cos on less then 100kg fuel used and in total by DCS around 17t locked. should be close in t/w ratio if RL j11 engine data is used. all that work on polishing was about achieving extra 3% on previous record done by Strike Eagle, i assume ofc. ill try eagle too.

that is what J11 is closer to by engine performance so closest thing to p-42 is J11 in RL in matter of wet thrust. it can be tweaked in lua file IF it has any affect.

in default su27/j11 i wasn't able to go above 600kmh. was using 48deg climb as used on mig31 previous attempts and that should be optimal.

i'll need few days to complete the scripting.

some patience pls. i think its gonna be interesting to see the difference.

Did you find any reference to the actual original climb profile.

While the П-42 was actually a serial production airframe, it was also modified heavily. That said Streak eagle was also heavily modified.

The way I see it you will end up creating a mod.

Edited May 30, 2023 by okopanja

[Ironhand]

1 hour ago, jackmckay said:

…in default su27/j11 i wasn't able to go above 600kmh. was using 48deg climb as used on mig31 previous attempts and that should be optimal…

I don’t know what’s optimal for the MiG-31 but an Su-27 is not a MiG-31. In my 2nd attempt, I reached 12,000 m in 1’ 27” starting with 28% fuel (the first took 1’49” with 30-something fuel) both of which suggest that your profile is suboptimal. In both flights speeds above Mach 1 were achieved.

EDIT: Also just occurred to me that the Su-27DCS has an acceleration drop in the transonic range that ED claims they have data for but is not demonstrated in publicly available data. So given the short time constraint involved, I suspect you won’t get all that close to the P-42 time.

Edited May 30, 2023 by Ironhand

[Pavlin_33]

9 hours ago, jackmckay said:

do you have some links pls.

It should be this one here:

 

1 hour ago, Ironhand said:

...

EDIT: Also just occurred to me that the Su-27DCS has an acceleration drop in the transonic range that ED claims they have data for but is not demonstrated in publicly available data...

Would be amazing if they shared this publicly with the rest of us.

[Exorcet]

If the issue here is Su-27 performance, comparing to the P-42 is not helpful.

I've seen some anecdotal evidence for Su-27 performance issues, I know that FC3 stores drag is not as well modeled as full modules, and I know that the AI Su-27 can't even keep up with the player one, despite AI generally overperforming. However all of this is unrelated to the P-42.

[Ironhand]

Made a few more runs. My best time so far from brake release to 12,000 m on the info bar rather than the HUD (the HUD gets to 12,000 m sooner) is 1’29”. My previous reported time of 1’27” was from wheels leaving the runway to 12,000 m. I hadn’t noticed TheFreshPrince’s post until after posting.

And this is where I’ll probably stop because I doubt I’ll be able to shave more than another few seconds off that time.

Edited May 31, 2023 by Ironhand

[draconus]

On 5/31/2023 at 8:24 PM, Ironhand said:

My best time so far from brake release to 12,000 m on the info bar rather than the HUD (the HUD gets to 12,000 m sooner) is 1’29”.

Nice, what was your flight profile? You can even use less fuel than 15% I noticed.

[Ironhand]

6 hours ago, draconus said:

Nice, what was your flight profile? You can even use less fuel than 15% I noticed.

That one was somewhat like the afterburner intercept flight program laid out in the real world manual.

Yesterday I made one more flight despite my promise to myself not to. That one came in at 1'21".

In this last one I used both active pause and jackmckay's 1% unlimited fuel. I hadn't expected much difference but there was. This time I followed the flight program (maintain M0.9-0.95) until I passed through roughly 7000m. If you continue to follow the program from that point, you have to start reducing your pitch angle to hold required Mach and I know from experience that it'll make the flight longer. So at that point I pulled into a zoom climb. It's fun flying with no fuel... Track attached.

Su-27 12000 m Climb_Unlimited-1-21.trk

Edited June 2, 2023 by Ironhand
Add TRK

[okopanja]

@Ironhandslighlty worse than you:

https://snapshots.raintank.io/dashboard/snapshot/Trofr6wHWdBKim7gP65TrFsmoD0rd2U2

[Ironhand]

1 hour ago, okopanja said:

@Ironhandslighlty worse than you:

https://snapshots.raintank.io/dashboard/snapshot/Trofr6wHWdBKim7gP65TrFsmoD0rd2U2

@okopanja I think that the difference is the climb angle to Mach 0.95. Judging from the plots of our speeds, your angle was steeper than mine. EDIT: That assumes our aircraft were set up identically.

Edited June 7, 2023 by Ironhand