Tango

This was exactly my finding, too. Drag too high and/or thrust too low. Try gliding at idle - you'll find the drag to be too high (very high sink rate/short glide distance). Chart is on the bottom of page 12. Best regards, Tango.

Hi, My first approach was borked because I started on final and haven't flown today, but the rest is just to show you that it doesn't matter how poorly you fly, so long as you get the speed and thrust correct, you can land off most approaches without problem. Best regards, Tango. MiG-21 Landing Approaches.trk

Wow... hmmm. Let me make a track for you. Best regards, Tango.

How do you figure the time allowed to accelerate? Best regards, Tango.

I think he means the update that is imminent. They locked the files so some changes will appear in the update after. Interesting comment on distance calc. 870 kph = 470 kts. For the stated condition of clean this should be easily attained within this time period, and comfortably so with some load I would have thought. With boosted afterburner, it has a power to weight ratio close to 1 at takeoff. Best regards, Tango.

Hmm - what if the climb is conducted at 600 kph IAS, accelerating to 870 kph TAS, then TAS climb when 600 kph IAS == 870 kph TAS? Best regards, Tango.

Oh... I see what you mean... In that case, will the sim climb in 60 km distance? Best regards, Tango.

Why not? Example: 7000 m, 4 mins 10 sec, 40 km (climbing at 870 kph TAS) Ground speed at sea-level: 870 kph Ground speed at 7000 m: 870 kph The reason for the same value is because in zero wind conditions at ISA, ground speed = TAS. Average vertical speed: 28 m/s Average climb angle: 9.92 degrees This should be easily within the capability of an aircraft like the MiG-21. Best regards, Tango.

Hi, Thanks for the explanation. Whilst it is understood that high altitude and small wings are a bad combination, we can't escape the fact the manual states climb profiles, time and distance to altitude, that we can't match (we end up with climb distances over double the stated values). There can be only one of two possibilities: * Either the FM needs tweaking or * The manuals are wrong I also checked glide performance from a modest 7000 m, and far from matching 70 km, I managed only 20 km. This strongly suggests a problem with the drag of the FM. Best regards, Tango.

It's still no clearer. The "no brake turning" ability seems to be airspeed derived. I tried applying a high power setting (80%) with the brakes fully applied, released the brakes, then applied rudder before the aircraft accelerated, and I didn't see any turning until the aircraft passed ~25 kph. In the posts above, was the suggestion that differential wheels brakes are automatically applied with rudder, and that the turn is still brake induced even though we are not pulling the brake lever ourselves? Best regards, Tango.

BLC system increases lift by promoting laminar flow over the wing/lifting devices. The result is that it reduces the AoA experienced by the wing, and increases lift (you can see this effect on the AoA indicator - it reduces by approximately 2 degrees in the case of the MiG-21 when the system is operating). A stall is because the air flow is disturbed, and separates from the surfaces. This flow seperation is turbulent, and adds drag as well. Best regards, Tango.

Nice job! 8) Best regards, Tango.

System is activated when: * Flaps landing position * Speed < 380 kph IAS It is definitely modelled - if you reduce power to idle, she drops out of the sky faster than the speed bleeds off. Best regards, Tango.

Fixed! :P Best regards, Tango.

You are mixing multiple things. DIFFERENTIAL BRAKES are linked to the rudder, and require use of the brake handle, period. NOSE WHEEL STEERING LINKED TO THE RUDDER is something else entirely, and the aircraft behaves like this only connects at speeds > 40 kph (to me it seems more like 25 kph). Thus, when taxiing VERY SLOWLY, the ONLY way to turn is with DIFFERENTIAL BRAKING. At high speed (let's say 100 kph) then NOSE WHEEL STEERING is available. I'm very intrigued as to why it doesn't have full-time nose wheel steering, and how the system works. Best regards, Tango.

@Corrigan: as interesting as that would be, it doesn't explain why 3 AFM aircraft by 3 different developers, written years apart, all have the same basic problem with high altitude flight. The common element is DCS itself. Best regards, Tango.

There is one commonality between them all (don't forget A-10C has the same problem with high altitude flight): physics integrator of DCS. It also explains a rather intriguing behavior with our very own L-39. Best regards, Tango.

Thanks! Best regards, Tango.

I stated them several times now. It is the profile the manual assumes for the table data. Again: * Takeoff using full reheat to 600 kph IAS * At 600 kph IAS, cancel reheat * Accelerate to 870 kph TAS * Climb to altitude at 870 kph TAS Note carefully IAS and TAS!!!!!!!! MANUAL STATED CLIMB PERFORMANCE FROM POST #1 Clean: * 7000 m, 4 mins 10 sec, 40 km * 10000 m, 7 mins, 82 km 2x R-3S, 1x 490 L center-line drop tank: * 7000 m, 4 mins 40 sec, 47 km * 10000 m, 8 mins 10 sec, 98 km Once achieving cruise alt at 870 kph TAS, reduce power to maintain 530 kph IAS max range cruise speed. Allow me to state it again: in the current build that we have, it is impossible to maintain cruise speed without reheat. In addition, the climb distances are waaay off. I'm reaching 8000 m at a distance of 120 km, and unable to reach the cruise altitude following the climb schedule, which should be easily achieved. Interesting that no-one commented on my track yet. See my post here: http://forums.eagle.ru/showpost.php?p=2185785&postcount=42 Best regards, Tango.

@159th_Viper: I'm interested to know what is different, if you are running the same build as us. Can you attach your mission file used for testing? Best regards, Tango.

I use SAU for the level flight testing. There is even a table for the altitude loss incurred by activating it. Best regards, Tango.

I don't doubt you - question is - what is different then? I tried the "best case" scenario - clean jet. I can't do it. Best regards, Tango.

Well, with the build I have, I can't. I lose airspeed, and eventually stall. Best regards, Tango.

No, sorry - Viper. He wrote: Regardless of zoom climb - it is (currently) not possible to maintain speed at full power (no reheat). I posted a screenshot series further up demonstrating this. Best regards, Tango.

You are forgetting the *very specific conditions*: * Takeoff using full reheat to 600 kph IAS * At 600 kph IAS, cancel reheat * Accelerate to 870 kph TAS * Climb to altitude at 870 kph TAS Note carefully IAS and TAS!!!!!!!! Best regards, Tango.