What is the lowest spaceplane takeoff speed?

[Numerlor]

with one spaceplane I can takeoff at 50m/s, I suppose adding more wing area would lower that speed?

Spoiler

 

Edited February 18, 2017 by Numerlor
Added images

[Gaarst]

It could. Adding wings also increases mass and drag, reducing efficiency.

For a spaceplane, a takeoff speed of 50m/s is already pretty slow: if you can generate enough lift to take off at this speed you probably already have a lot of wing area weighing you down.

[Tex_NL]

And with enough thrust (TWR > 1) you can lift off vertically at 0m/s.

High lift craft can struggle to lift off with poor design. Low lift craft can be airborne before you realize it. Take off speed completely depends on craft design.

[Ultimate Steve]

This reminds me of the ion plane research challenge. I don't remember, but someone got a plane to glide at 20m/s before. The main obstacle from taking off at sea level is the poor thrust of the ion engines, and therefore a slow takeoff speed was required. I think the highest anyone actually got on the runway was 14m/s.

But my non-sea level ion planes did pretty well and had pretty low takeoff speeds, as most of the mass had to be wing.

[strigon]

Designing spaceplanes - like everything else - involves making sure you optimize the vehicle for what it has to do.

Since you called it a spaceplane, I'm assuming you want it to reach space? If this is the case, takeoff speed doesn't matter, and - as others have mentioned - decreasing takeoff speed comes at a cost to other aspects of your craft - specifically, speed and efficiency, which are important to a spaceplane. If anything, this is a sign that you should tone down your craft's wing usage.

Now, if you didn't intend for it to go to space, and you instead want a glider or low-speed, low-altitude plane, then yes, increasing wing area will decrease takeoff speed. But before looking into those options, I'd recommend switching to a more reasonable engine for that task (smaller), or decreasing fuel capacity, as those will likely have a more immediate effect for a lower cost.

[Numerlor]

11 minutes ago, strigon said:

Designing spaceplanes - like everything else - involves making sure you optimize the vehicle for what it has to do.

Since you called it a spaceplane, I'm assuming you want it to reach space? If this is the case, takeoff speed doesn't matter, and - as others have mentioned - decreasing takeoff speed comes at a cost to other aspects of your craft - specifically, speed and efficiency, which are important to a spaceplane. If anything, this is a sign that you should tone down your craft's wing usage.

Now, if you didn't intend for it to go to space, and you instead want a glider or low-speed, low-altitude plane, then yes, increasing wing area will decrease takeoff speed. But before looking into those options, I'd recommend switching to a more reasonable engine for that task (smaller), or decreasing fuel capacity, as those will likely have a more immediate effect for a lower cost.

Well that little "space" plane on image can get apoapsis above 90km so with little help it could achieve orbit and still can take off at low speeds (I just made it to test how much G-Force I can make with spaceplane) 

[natsirt721]

Wing area is important but so is shape. If you want an aircraft with a low stall/takeoff speed, build long thin wings (high aspect ratio). Beware that high AR wings will perform very poorly at Mach numbers greater than ~0.8 due to a proportionally large increase in drag. For reference, most of my spaceplanes need between 70 and 90 m/s before rotation, and although I'm certain you can do better, stall speed isn't a huge deal for spaceplanes in general.