Is achievingorbit that easy?
 

I was doodling an SM+3 design for a reentry* vehicle using Spaceships when the possibility of using it for relaunch occured to me.

Basically, reentry capable only, would be 1 armour, control in both cores for one crew, 3 passenger seats (15 spaces), a soft-landing system and a combined fuel/power and drive section to achieve de-orbit.

But, if you replace 2 passengers with fuel tankage, a streamlined winged design can achieve orbit in a couple** of minutes? I must be doing the arith wrong...

*emergency, sport or military stealth unit.
**eg 2/3 g for approximately 2 minutes.
PS: I understand Spaceships is less accurae below SM+5 but it's not likely I'll be making any reentry vehicles.
PPS: you could replace passenger seats with hibernation or nanostasis modules and travel around waiting for rescue.

Re: Is achievingorbit that easy?
 

I haven't read what you refer to (no clue what SM+3 design for reentry refers to), but it's sounding like a winged design. You can't use wings to reach space. The higher you go, the lower the air pressure, and therefore the less lift wings can produce. If the air is thin enough, it just won't support the winged vehicle anymore.

Re: Is achievingorbit that easy?
 

What type of drive did you stick in the little guy? What TL is it? Both of those are rather important questions.

Re: Is achievingorbit that easy?
 

I refer to my own doodlings and guesstimates/ extrapolations from Spaceships tables.

According to Spaceships, on page 37 and 39, you can make it to orbit in an atmosphere if you have wings. It provides formulae for time taken. I think the idea is that by the time your lift medium is gone, you're high enough that your thrust exceeds gravity at that altitude, but I'm just guessing.

I started out to design a cheap tin-can for escapes from spacestations and ended up discovering a space-taxi.

Re: Is achievingorbit that easy?
 

The atmosphere is an almost unimportant, super thin film when compared to orbital distance.

Re: Is achievingorbit that easy?
 

Funnily enough, neither are relevant. They only alter cost and time taken to achieve orbit, and whether you need fuel or power plants...
It's all just guesswork for SM+3 but the same ratios apply as if it were an SM+6 design using SM+5 subsystems for drive (plus lots more passengers).

What befuddled me was, according to the numbers I played with, I could build it as 53% fuel tankage, 2/3g of thrust from a subsystem HEDM rocket and fly to orbit in something like 4 minutes? And there'd be fuel to spare.

Re: Is achievingorbit that easy?
 

I think you've either misread what orbital velocity is or simply broken the system by trying to stretch it too far.

To reach orbital velocity in 2 minutes you'd need to pull a steady 6 Gs and wings don't change that.

Re: Is achievingorbit that easy?
 

Aha. We now see. Yes, if you have HEDM rockets, getting into orbit is trivial. Sadly, we don't have HEDM rockets today, nor do they look all that likely in the near future.

Re: Is achievingorbit that easy?
 

When either or not a spaceship has wings, fins or about any other design feature makes no difference to achieving orbit. (Baring weight/air resistance).

The main reason an atmospheric plane etc cannot achieve orbit is the fact that jet engines and propellers do not work in a vacuum.

Else its simply a matter of thrust vs gravity.

There are space ships today that use jet engines to get as high as they can like a plane then hit the rocket engines to go the last mile as it were.

Re: Is achievingorbit that easy?
 

Actually, it does -- a spaceship with wings can in principle achieve orbit without every having thrust exceeding 1G, a spaceship without wings cannot.