SSTO Problem

[SteveD80]

I am trying to build an SSTO, and am struggling with gaining altitude.  It seems to top out around mach 1 and even with a TWR > 1 it slows down if the nose is pointed up.

[Gaarst]

Pics. They help.

[bewing]

Mach 1 is an important crossover point for all the engines. If you can get through it, suddenly your engines start gaining tremendous amounts of power and thrust. Generally, if you have that problem you want to climb slowly to 8 to 10km altitude (if you can get that high, climbing at 200 m/s or so) -- then crank it up to full power and go into a shallow dive to get through that Mach 1 boundary.

[Justicier]

^ What bewing said. However, since your craft has a TWR greater than 1, I have a couple questions. What kind of engines are you using... RAPIERs? A Combo of Whiplash+Rocket motors? And what about the intakes... Shock cones? Radial air intakes? This is important because different engines will be more or less capable at different altitudes and speeds. The type of intake is also very important as some will not provide much if anything for the engines at supersonic and hypersonic speeds.

Generally speaking, if you want your plane to go to space today, you should consider using a minimum of Whiplash jet engines for getting your speed and angels (altitude), then rocket motors (preferably aerospikes) for the last push from high altitude to orbit when the air has gotten too thin and the jets cough out. If it is available, the RAPIER engine used in conjunction with Shock Cone intakes is probably your best bet since that combo has the best high-altitude, hypersonic performance (well, in KSP terms).

This is of course all assuming that your plane is nice and aerodynamic... I hope you're not trying to get a brick to orbit

Edited October 15, 2016 by Justicier

[ForScience6686]

I believe aerodynamics pay a bigger role now.  My understanding is pointy and blunt objects relate to drag more realistically.  And if you're having trouble at the mach barrier I would assume this is your problem.  Reducing unnecessary radially attached components and minimizing air intakes is key.  However, with the thrust you claim to have, improper engine our intake selection could be a problem.

 

Pictures will help immensely.