I'm pretty sure this is already planned considering the ongoing rework of the F-16C and F/A-18C radars, but it's definitely worth saying. The differences in radar modeling between modules are very visible and going back to an older (or just worse) implementation is quite painful.
Because that's where the bombers flew. Flying high gives you a much better range and - as you noticed - makes you difficult to intercept. So that's what the B-29s did. The MiG-15 was built to deal with this threat and so high altitude intercepts were the bread and butter of MiG-15 pilots. Take off, make best climb into the stratosphere and catch the guy before he gets away or you run out of fuel. Just like BFM or making carrier traps it requires thought, practice and knowing your aircraft well.
I encourage you to get familiar with chapters 8 and 9 of the flight manual as well as the concept of "coffin corner":
https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)
There are several things that work against you at high altitudes. Firstly, your engine can generate (significantly) less thrust in thin air. You cannot maintain airspeed in turns or recover it as well as down low.
Secondly, there is the "coffin corner".
when it comes to airspeed, your low limit is 300km/h indicated (citing the manual):
Your high limit is officially Mach 1:
but really, you'll be experiencing serious controllability issues much earlier:
Notice how your low limit is expressed in kilometers indicated and your high limit is a Mach number (true airspeed). As you get higher a given indicated air speed corresponds to a higher true airspeed/Mach number. If my online calculator hasn't lied to me, at sea level 300km/h indicated corresponds to Mach 0.25, while Mach 0.86 (so the Mach number where controllability starts to suffer) is 1050km/h. That's a difference of 750km/h to play with. And you get plenty of engine power to boot. At 15500m 300km/h is now Mach 0.7, while your upper limit of Mach 0.86 corresponds to 378km/h. That's less than 80km/h of difference! In other words, at 15500m you are almost stalling and at the same time almost out of control because of being too fast. And you can barely maintain that speed because your engine is at its limit.
The good news is, the Sabres aren't much better. They can go a little faster without losing control but their engines are weaker and their ceiling should be lower (it was IRL, I haven't done any extensive testing in DCS).
So what can you do at or close to the ceiling? Now I'm no expert, but here's what I do:
- Keep your airspeed indicators in your scan at all time. Pay attention to both your indicated and your true airspeeds.
- Forget about aggressive maneuvers, particularly in the vertical. Lazy turns and shallow dives and climbs only.
- Practice identifying overspeeds early and getting out of them. Read the manual, practice how your ailerons, rudder and elevators react at high Mach numbers. You probably will end up messing up and overspeeding from time to time, but if you can catch it early, you can often correct the problem without a huge loss of altitude.
- Pay attention to your fuel state. In order to climb to the service ceiling and stay there you will need to be flying at full throttle. You really won't have much time before you have to turn back.
In the end, like everything in DCS, it comes down to practice. Practice efficient climbs to stratosphere altitudes, practice how the aircraft behaves at 8000m, 10000m, 12000m, 15000m. Shoot down some non-maneuvering targets first, then move on to maneuvering ones...
Good luck!
