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I've been looking at the altitude boosted SSTO designs from the 90s that were designed to be lifted to launch altitude by modified jetliners and thinking about bumblebees and wondering if bioships used for surface-to-orbit cargo transfers could make use of insectile wings to gain altitude before using a liquid-fuel rocket to boost into orbit proper.

What I want to know is would it be metabolically worthwhile for a creature weighing some 15,000 metric tonnes fully laden to use biomechanical insectile wings, with a similar structure to and operated by the same muscle-based mechanism as, those of a bee, wasp, or dragon fly etc... they need not be materially identical in fact I'm reasonably certain they can't be (are such even materially possible on this scale at all?) to gain altitude before engaging a liquid hydrogen-oxygen rocket or would boosting directly from the ground be more efficient?

I believe that bumblebees have the most metabolically efficient wings of any organism but if you know that isn't so then use whatever does as the basis of comparison. Base the energy cost of fuel on electrolysis of water.

I've looked at this question on engine systems for bioships but I want to know whether it is worthwhile to use wings to gain altitude before using a particular engine, in this case a hydrogen-oxygen liquid fuel rocket motor.

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    $\begingroup$ "biomechanical insectile wings" what criteria makes something count as such wing? Looks? Technical parameters? Something else? $\endgroup$
    – Mołot
    Jun 30, 2019 at 15:12
  • $\begingroup$ @Mołot Does that clarify my intent? $\endgroup$
    – Ash
    Jun 30, 2019 at 15:22
  • $\begingroup$ I added flight because you're asking about a method of taking the ship from the ground to a higher atmosphere before blasting off into space. $\endgroup$
    – Cyn
    Jun 30, 2019 at 15:35
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    $\begingroup$ What answer? I just supplied a piece of elementary physics. The way insect wings generate lift simply does not work for objects larger than a hummingbird. It's not that it is inefficient: it does not work. Insect wings depend on being small, with dimensions comparable to the thickness of the boundary layer. Size is not everything, but it is really important. $\endgroup$
    – AlexP
    Jun 30, 2019 at 19:53
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    $\begingroup$ Bioships may be a staple of SF, but it is generally a terrible idea to use organic technology outside of its niche. $\endgroup$
    – Eth
    Jul 1, 2019 at 10:02

2 Answers 2

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As said many times here and in many other places, the problem with going to space is not about going high enough (a flight from Amsterdam to Tokyo travels more linear distance than a flight from Cape Canaveral to ISS, you could cover the distance to space in 1 day with a bike and a bit of exercise), but it's more about going fast enough.

Orbital velocity is about few kilometers per second. Insect wings can reach up what, few meters per second? And they would have to lift not only the body, but also all the fuel that the subsequent rocket stage would need.

The only advantage I could foresee would be to reach past the max Q zone before starting up the rocket. But the max Q height is about 11 km, way past the level where insects can fly.

Long story short, I see no advantage.

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    $\begingroup$ Yeah you haven't seen what happens when I try to ride a bike, that consists entirely of me falling over, but the point is taken distance isn't the issue and height isn't helpful until it is which is much farther into the trip than its feasible to go this way. $\endgroup$
    – Ash
    Jun 30, 2019 at 15:36
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    $\begingroup$ @Ash orbiting is of course the act of falling fast enough in the right direction and missing what you're falling towards. You've clearly got the right idea, you just need to up your speed a little... $\endgroup$
    – Starfish Prime
    Jun 30, 2019 at 19:21
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TL;DR: you can't make a space-shuttle sized thing fly like a bumblebee, because engineering isn't scale-independent.

In addition to the obvious issues (eg. you'll save very little over a conventional rocket launch) the other major problem is that bees are small and light, whereas things that are considered to be surface-to-orbit cargo vehicles are very much neither of those things.

The old quote about bumblebee flight being aerodynamically impossible is obviously a load of cobblers, but a bumblebee the size of a space shuttle clearly cannot fly in the same way as its tiny prototypes. Viscous forces on something that is tens of metres long and tens or hundreds of tonnes in weight can be largely ignored, but for insects they are very important indeed. Have a read of this physics SE answer on that subject.

Furthermore you're gong to come very unstuck when you start having to deal with issues of stiffness and the strength-to-weight ratios of the materials you're growing your bioships out of. To oversimplify: scaling things up either makes them unreasonably heavy or unreasonably flimsy (that good old square-cube law that has slain so many fictional megafauna and giant mecha). Whatever putative efficiencies you thought you'd start with will be long gone.

Finally... why bumble bees? They're not the strongest or fastest insects; they've got a neat trick of heating up their bodies so they can be active earlier in the day than other pollen-hunting flying insects, and they're moderately manoeverable and they can hover pretty well, but none of those features are very useful for something whose main job is to carry some heavy stuff upwards, transition to some totally different flight mode, and then reverse the process. Using a flight mechanism optimised for none of those things seems odd!

(oh, and finally finally, if you can make 15000 tonne artificially-designed biological constructs capable of self-powered flight and survival in space, surely you're capable of doing something much simpler like implementing one of the many means of non-rocket spacelaunch?)

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