Hi altitude in the 21?

Hi, sure I must be doing something wrong, but is it possible to get high and fast in the 21?

I've tried to get >9000 meters, and have just had no luck, even with less than 1000 in fuel, no stores and full AB, I cannot get past 700km/h flying level at that altitude. Even 5 deg of climb will induce a stall at those heights.

Seems to climb fine in mil up to about 8000 meters, and after that it just wont climb much no matter how much power is applied. Was under the impression it could do mach 2 at higher altitudes, but not sure how.

It's very easy, just use your afterburner without any extra load/tanks and stay fast, first you will climb like a rocket, later the climb rate will be a bit lower but at really high altitudes the aircraft should even climb at Mach 2. Also at some point you should use the Mach number instead of IAS in your cockpit but never go below 500kph IAS. With that it should be easy to get to 15 - 20km at Mach 2.

Hi, sure I must be doing something wrong, but is it possible to get high and fast in the 21?

 

I've tried to get >9000 meters, and have just had no luck, even with less than 1000 in fuel, no stores and full AB, I cannot get past 700km/h flying level at that altitude. Even 5 deg of climb will induce a stall at those heights.

 

Seems to climb fine in mil up to about 8000 meters, and after that it just wont climb much no matter how much power is applied. Was under the impression it could do mach 2 at higher altitudes, but not sure how.

With a center fuel tank, you should be able to reach 15K meters comfortably.

Takeoff. Do not climb immediately. Instead, maintain level flight until your TAS is right around 1200 km/hr. At that point pitch up 10-15°. Keep an eye on the TAS. If it's increasing, slowly increase you pitch further. If it begins decreasing, slowly decrease your pitch. The goal is to hold the TAS right around 1200 km/hr on the way up. When you reach 15,000 level off gently and enjoy the view.

FWIW, with 2 missiles and a centerline tank, 11,000 m should be attainable with ease as well.

15,000 meter track attached.

High Altitude Climb.trk

I just watched a vid on a retired Finnish pilot relating how the Mig 21 had to be put into a climb at full AB to stay below 2.08 M or thereabouts, as that was the max speed. It was neat seeing the same behavior in the DCS version of the mig.

The problem you may be having is the fact that it just takes a long time to climb. For me to get to 60k feet and 2.1 M, it takes the distance from Tsibilisi, to Kobuleti. I drop my tanks around 40k, and then crawl up the remainder, trying to get stay as fast as possible. Eventually, I get to 2.1M with about 1-2000L of fuel remaining (after starting with three drop tanks). It is possible to climb slowly to about 71k, but beyond that altitude, It will flame out.. It always flames out if you exceed 2.1 M.

The highest Ive ever taken the mig is 97, 400 feet in a zoom climb, which was pretty cool. Have to start the climb in at around 50000 feet as fast as you can to get that though.

I just tried the 1200km/h climb and it got up to alt and max mach way faster than my usual plodding climb speeds. Was cruising at max half way to kobuleti from tiblisi this time. That was in a clean config.

Does anyone know the best climb speed with three tanks? Was barely climbing at 1100. Hard to reach 1200. It climbed a bit better at 900km/h, but still pretty slow. Anyone know the majic number?

I just tried the 1200km/h climb and it got up to alt and max mach way faster than my usual plodding climb speeds. Was cruising at max half way to kobuleti from tiblisi this time. That was in a clean config.

 

Does anyone know the best climb speed with three tanks? Was barely climbing at 1100. Hard to reach 1200. It climbed a bit better at 900km/h, but still pretty slow. Anyone know the majic number?

When acceleration and deceleration is 0, at a certain rpm and pitch set up with any load, that is your magic number.

I just tried the 1200km/h climb and it got up to alt and max mach way faster than my usual plodding climb speeds. Was cruising at max half way to kobuleti from tiblisi this time. That was in a clean config.

 

Does anyone know the best climb speed with three tanks? Was barely climbing at 1100. Hard to reach 1200. It climbed a bit better at 900km/h, but still pretty slow. Anyone know the majic number?

First of all, what altitude are you expecting to get to with 3 external tanks? I'm guessing that 10K (±2K) would be the top. Haven't tried it myself. That's why it's a guess. But somewhere in there should allow level flight at 550 km/hr IAS which is about as slow as you want to get (even though I sliced it a bit thinner in my flight because I wanted to reach 15K).

And, because your speed is less with those tanks attached on the way up, it will be slower getting there.

First of all, what altitude are you expecting to get to with 3 external tanks? I'm guessing that 10K (±2K) would be the top. Haven't tried it myself. That's why it's a guess. But somewhere in there should allow level flight at 550 km/hr IAS which is about as slow as you want to get (even though I sliced it a bit thinner in my flight because I wanted to reach 15K).

 

And, because your speed is less with those tanks attached on the way up, it will be slower getting there.

Expecting to get to about 10k meters in altitude. But what I was really wondering is how to get there the fastest way possible. When you said before to climb (clean config) at 1200kph, I was surprised because I didnt expect best climb speed to be that high. It was really cool to get up to speed and altitude so quickly compared to the speeds I was flying before.

When I tried fast speeds with the 3 tanks 900-1100kph, it climbed really slowly. So I burned through my gas very quickly at low altitude (secondary AB lit). If I can find the best climb speed, then I can get up into the thin air quickly and really stretch the range.

How it is done in RL BIS and works very well in DCS also (Flight for maximum MACH or maximum ALT from RL BIS manual), it needs some training:

It is important to know, that you need to get past Mach 1.4 for the engine to start to bite. From 1.4 to 1.6 acceleration will get better, and once over 1.6 and the intake starts to move, then you'll be over mach 2 very quick.

My profile is to get to 8-10 km altitude subsonic, drop the tanks, then accelerate in a shallow descent to M 1.4 (careful not to induce a flameout with too high IAS). Over 1.4 start shallow climb, once over 1.6 you can increase rate of climb.

Once over Mach 2 you do need either to throttle back or climb or turn otherwise you hit the max Mach and engine will flame out.

What the documents mentions about supersonic speeds is quite a hint, the MiG-21has a high Q limit, meaning you can’t go supersonic below about 5k meters. It really is best to get it supersonic at 10k. I always find it breathtaking how well it can sustain high speeds(in a straight line). Even with four missiles I think it can still reach Mach 1.8. You’ll get there. Thing is, I don’t think three bags is a recommended load out, I think it’s suppossed to be two on the wing or centerline, but not all three. Sure it’s nice because afterburner time, but the drag penalty starts to add up,

When reading the IRL manual, keep in mind that in peace time supersonic flight was not allowed below 10000 m due to the sonic boom. So that instruction to climb and maintain 10km might not be for performance reasons...

True. As long as your above about 5k meters it should be possible

1200 km/h indicated at 10000m is just Mach 1.6, thats the speed I mentioned when the engine really comes to life. You can get there faster if you descend during acceleration initially. Just don't exceed that hard coded IAS limit.

I find that between M 1.1 and 1.4 it is a struggle, once over 1.4 it is getting better, over 1.6 it is a rocket.

How it is done in RL BIS and works very well in DCS also (Flight for maximum MACH or maximum ALT from RL BIS manual), it needs some training:

 

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Thanks for this. Hopefully I'll have an opportunuty to put it into practice later this week.

When reading the IRL manual, keep in mind that in peace time supersonic flight was not allowed below 10000 m due to the sonic boom. So that instruction to climb and maintain 10km might not be for performance reasons...

On my flight I noticed a sudden increase in thrust at around 7-8K meters. I had accelerated without lowering my pitch and thought: That's interesting. I wonder what that's all about. I'll have to check it out the next time I'm up. Now I guess I know.

I’m loving the info and comments in this thread. As an aside, I tend to prefer physics based simulation, as opposed to one that run primarily off of tables (aka, scripted) like DCS...but that flight manual excerpt goes to show how much of aviation really is actually scripted. And the cooler the plane, the tighter the script. That linked except reads like a play! Deviate from the script at your peril!

Funny, all of aviation is like that. So many tend to think of aviation as giving you freedom of flight. Then you get into it for real and get surrounded quickly by procedures and checklists. Not that I’m complaining, as that is what keeps you alive and develops competency.

I guess you can get that feeling of freedom of flight, but it happens in those short in between moments, and you can never linger there...because the script awaits!

Tabular data <> scripted.

Aerodynamics is far from being simple linear equations and real-time computational fluid dynamics of any accuracy aren't even possible on a PC. Tables provide two key aspects to real-time flight simulation: 1) looking up a number in a table is much faster than calculating one and 2) given sufficient dimensions/resolution, tables of data derived from emprical data are far more accurate than any real-time physics calculations that can be performed on a PC, especially for transonic and supersonic aircraft.

Name one flight simulator available to consumers that doesn't rely on data tables. Don't say X-Plane, because its blade element theory is far from accurate and anyone doing serious training/research using X-Planes' engine is inserting their own flight model, which is typically going to be comprehensive tabular data from real flight tests, wind tunnel tests, or advanced computational fluid dynamics.

+1 That's one of best description about tables and the blade element theory I've ever read!! :thumbup::thumbup:

How it is done in RL BIS and works very well in DCS also (Flight for maximum MACH or maximum ALT from RL BIS manual), it needs some training:

 

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Finally had an opportunity to fly this profile—though I didn’t include the turn back toward the airfield. Great fun! The climb ended at 20,760 m and settled in to level flight at around 19,500. Didn’t take long to get there either.

Thank you again.

Tabular data <> scripted.

Aerodynamics is far from being simple linear equations and real-time computational fluid dynamics of any accuracy aren't even possible on a PC. Tables provide two key aspects to real-time flight simulation: 1) looking up a number in a table is much faster than calculating one and 2) given sufficient dimensions/resolution, tables of data derived from emprical data are far more accurate than any real-time physics calculations that can be performed on a PC, especially for transonic and supersonic aircraft.

 

Name one flight simulator available to consumers that doesn't rely on data tables. Don't say X-Plane, because its blade element theory is far from accurate and anyone doing serious training/research using X-Planes' engine is inserting their own flight model, which is typically going to be comprehensive tabular data from real flight tests, wind tunnel tests, or advanced computational fluid dynamics.

This. There's a reason why a -ton- of science is done by tabulating models before hand rather than calculating everything on the fly each time.

My record was 22 km. The aircraft was ballistic by that time as none of the controls were effective. Just had to wait until it starts to fall back into thick air. At the top of the trajectory I had a zero gravity and engine flamed out. Relit it around 12km and returned safely. Did all this with no stores and full internal fuel.

Tabular data <> scripted.

Aerodynamics is far from being simple linear equations and real-time computational fluid dynamics of any accuracy aren't even possible on a PC. Tables provide two key aspects to real-time flight simulation: 1) looking up a number in a table is much faster than calculating one and 2) given sufficient dimensions/resolution, tables of data derived from emprical data are far more accurate than any real-time physics calculations that can be performed on a PC, especially for transonic and supersonic aircraft.

 

Name one flight simulator available to consumers that doesn't rely on data tables. Don't say X-Plane, because its blade element theory is far from accurate and anyone doing serious training/research using X-Planes' engine is inserting their own flight model, which is typically going to be comprehensive tabular data from real flight tests, wind tunnel tests, or advanced computational fluid dynamics.

All very good points about the use of tables. The reason I prefer “physics based” is probably coming from left-over bad impressions from early iterations of MSFS. I can be kind of obsessive about stuff. I’m the type of guy that can fly nearly the same flight 100 different times just to explore and feel out how the model behaves in slightly different situations. I remember being like that forever with flight sims.

My moment, the thing that almost made me gag, was when I tried to hover the Bell Ranger in the earlier versions of MSFS, and realized it always “stalled” (like airplanes do), approaching zero knots. Not knowing anything about computers or programming at the time, that is when the curtain was pulled away and I saw “through” the flight sim, and it lost all believability. It scarred me for life :smilewink: Shortly there after, because of that, is when I learned about the tables in the config files for each airplane model.

While DCS can’t be compared to that level of horridness, sometimes it feels like I can still see the man behind the curtain. For example, the ultra reliable flameouts at set speeds on the mig, or the shudder of the Mi-18 as moves in/out of translational lift. I realize those things happen in real life, but they seem to happen in exactly the same way in the sim, every time. But both models have so many other convincing characterstics, that it doesn’t hurt the soul like MSFS’s early attempt at helicopters. Thankfully, eagle dynamics has improved some with modeling landings and landing gear loading, because the earlier attempts (probably 10 years ago) had some generic behavior and animations that by themselves kept me from really liking Loc on, or Flanker (whatever it was at the time)

Your point about “given enough resolution” does point to something important. With enough data points, with enough contingencies, a flight sim can be made to be convincing. I would have no problem with a tabular approach to modeling, as long as I cant tell. I suppose that is where the “art” lies in flight modeling and sim design.

(As an aside, just to give you an idea of how weird I am with this stuff, one of my favorite flight sims to this day was A-10 Cuba! Why? Because the plane modeled the entire landing, compression stroke, everything. It was totally convincing. I could land that thing alll day long just to see how the landing gear would take different loads. And it crashed really well. Emergency off field landings were always different every time. It was predictable, but not totally predictable, if you know what I mean. Ironically, the real A-10 may not actually behave that way, but it had me fooled. :D)

http://starfighter.no/hi-alt.html

Climbing to altitude at low speed, diving to reach > 1.3 Mach and then climbing while staying supersonic was done by 104s in real life, so that behavior definitely makes sense for the DCS Mig 21

That link on the starfighter was an interesting read over a cup of morning coffee. Very cool.

Over the last week or so I’ve been messing around more with the Mig21. I am now pretty consistent with fast climbs to 100,000 feet or a smidge more. Flight profile is pretty simplistic, but very touchy since it’s running near to max IAS or Max mach near the whole way.

Basically I take off with no tanks, full reheat (w secondary), and accelerate to 1250-1300kph and maintain at that speed in climb. Eventually, Mach number will climb to M2.0, and if you are precise, the IAS will also still be between 1250-1300. When those two parameters meet, you should be a little higher than 10,000 meters. At that speed and and altitude, mach2.0 will increase very quickly to 2.1., so you need to pull up smoothly but quickly at maximum AOA until you are near vertical, trimming back to get full elevator range to aid in the last portion of the pull up (Full AoA requires full stick deflection in the middle part of the pull up) Then, as you maintain vertical, simultaneously trim forward towards neutral so you dont end up plowing through the air while the wings are still biting. Sit back and enjoy the ride. If your fuel was below 1000L at pull up, you should coast past 30,000 meters.

If you dont make it in the first run, you may have enough fuel for a second attempt (if you dont mind a deadstick landing on the way home).

The A-12s and SR-71s also did the subsonic climb, pushover to supersonic then supersonic climb profile, too.

https://www.sr-71.org/blackbird/manual/6/6-12.php