Had a go at the new Experimental Darkstar challenge and it was genuinely so much fun! Reaching Mach 9 was quite cool and flying into the outer atmosphere.
Why does my Darkstar only speed up to 0.98MACH?
You might need to do a nose dive whilst you’re 40,000ft up high I reckon?
And I can’t use this mission to fly this jet. the fps will drop down to lower than 10fps.
but it works well out of this mission.
Wait, can you use the plane on a normal flight?
Yes, you can. Just made a flight over the northpole……with refuelling 
Oh lovely, wasn’t able to find the aircraft on the normal flight aircraft selection
yes…it can
New York to Rome: 1h 30m at mach 10. Amazing.
And in the middle of Atlantic the rise of the sun with the blue of atmosphere and the black of the space. It was the best flight that I ever made. WOW
Thank you Asobo and Microsoft for this wonderful gift.
It would be nice that be possible to flight over 275000 feet (now we are slight under karman line that delimite the outer space, 100 km), maybe at the height of the International Space Station, what a vision that would be.
But already now is a fantastic vision! 
275000 is a limitation of the game not the plane, if you build a rocket and flew it straight up it too would stop climbing at 275000’.
I’ve had that one exact same problem. Did you maintain +1.2 Gs until 20° during the pull after the unloaded roll to upright?
Not sure if this is on VR on just PC non-vr. Either way set your rendering quality to low-end on graphics options on the msfs . Otherwise find a better GPU PC. Also set your windows mixed reality settings (headset display) to performance instead of quality.
Yes, but realize no auto pilots, IFR nothing. But i guess it doesn’t matter as you can cover a 10 hour flight in 1 hour and one good thing is the VFR built in map on the plane helps a lot . Without it totally lost.
If you’re above mach 3 below 30K ft, the plane will be destroyed (especially if crash damage setting is hard). Make sure you’re above 20-25000 ft and then start pushing down slow 0.5g -0.8g to 10 deg or close to 0. You’ll see speed pickup. Then push down further below 0 to nev 10 deg until you speed stops or slows down . Keep it that way with optimal speed increase and then close to 2.50 mach pull up slowly 1.0-1.5g to + 10 deg above horizon and you’ll see speed increase quickly to mach 3. turn on scramjet and fuel cell . And you should start climbing fast to 8-9 mach. You’ll face the same problem at this speed. Repeat the same procedure above at this time push and pull until you hit mach 9.9 or 10. Important : Make sure you’re at 120000 - 150000 ft before you try to get to mach 10 when you’re between mach 8-9. So it gives enough room to climb before you hit 275000 ft. If you hit max altitude before reaching mach 10, you will be stuck at whatever mach number when you hit 275k ft. The only way to correct then is to dive down to 220K ft and then climb up using the same procedure above.