My simple and fast spaceship: poletan.

[bzflater]

I reached top speed of 5468 meters per second with it. It uses no mods whatsoever and was made in KSP 0.9.0 x4.

Update: poletan v6 can reach top speeds of about 6125 meters per second thanks to significantly heavier boosters in the first stage. It is slightly less stable, though.

[imsabbel]

Nice way to use those strats as stabilizers. I never thought of it... but as they are constant weight, there is no penality to makeing them as long as you want...

[bzflater]

Nice way to use those strats as stabilizers.

Yeah, it is 16 times lighter than using SAS modules so I decided to cut down on mass by replacing them.

[bzflater]

Update: added poletans 22-3 and 24.

22-3 can reach the velocity of about 7300 meters per second and 24 is too laggy to properly test it on my PC. (I am too impatient for 21 engines to fall off considering the fact that I only get one new frame each 2-3 seconds on my PC and I start next engines too soon, which leads to the whole rocket exploding)

Depicted on screenshot: poletan v24 shortly after the beginning of its' flight.

[sirmonkey]

i tested 24.. while it works.. it doesn't work that great.. first stage works brilliantly.. release the SRB's and it continues going up on the liquids.. but thats where the problem starts.. even on the liquids it can barely hit 150m/s releasing the first stage of liquids/tanks.. it slows down so much that it starts falling almost instantly so that you can never fire the second stage without blowing up the entire ship.. it probably needs some SRB's on the second stage.. but that will probably add to much weight and nullify any use they would of been..

[bzflater]

i tested 24.. while it works.. it doesn't work that great.. first stage works brilliantly.. release the SRB's and it continues going up on the liquids.. but thats where the problem starts.. even on the liquids it can barely hit 150m/s releasing the first stage of liquids/tanks.. it slows down so much that it starts falling almost instantly so that you can never fire the second stage without blowing up the entire ship.. it probably needs some SRB's on the second stage.. but that will probably add to much weight and nullify any use they would of been..

I tried launching it despite awful lags. After disconnecting 21 liquid engines I waited the rocket to stop and only then ignited next engines. It flew perfectly fine then and reached top speed of about 8 km/s.