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Old 10-12-2019, 08:48 PM   #1
Two8nine
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Default 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.
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Old 10-12-2019, 08:56 PM   #2
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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.
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Old 10-12-2019, 11:23 PM   #3
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Quote:
Originally Posted by Two8nine View Post
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.
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File Type: trk High Altitude Climb.trk (1.83 MB, 22 views)
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Old 10-12-2019, 11:24 PM   #4
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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.
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Old 10-13-2019, 04:53 AM   #5
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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?
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Old 10-13-2019, 10:03 AM   #6
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Quote:
Originally Posted by Cgjunk2 View Post
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.
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Old 10-13-2019, 03:30 PM   #7
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Quote:
Originally Posted by Cgjunk2 View Post
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.
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Old 10-13-2019, 04:32 PM   #8
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Quote:
Originally Posted by Ironhand View Post
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.
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Old 10-13-2019, 07:56 PM   #9
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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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Last edited by Dr_Arrow; 10-13-2019 at 07:59 PM.
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Old 10-13-2019, 08:05 PM   #10
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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.
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