SpaceX Grasshopper rocket launch filmed from aerial drone

Shawn Knight

TechSpot Staff
Staff member
Ever wondered what a 10-story-tall Grasshopper Vertical Takeoff Vertical Landing (VTVL) rocket looks like when it’s taking off – from above? Me either, but after watching the clip below filmed from a six-propeller hexacopter drone flying high above I can...

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9Nails

TechSpot Paladin
That was mind blowing. Had to watch it twice and I still can't believe what I'm seeing is real. It was worth watching every second of the video.
 
G

Guest

Oh my effing god was that awesome!! Simply incredible footage!! Wow
 

St1ckM4n

TS Evangelist
I thought the whole point of rockets burning up on re-entry was because of the sheer amount of fuel required to escape gravity. 700m is not escaping gravity. Then, more than double the fuel payload to ensure enough thrust for a safe descent.
 
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Guest

You don't need more than double the amount of fuel. As you're climbing, air gets thinner and you burn fuel, meaning you encounter less resistance and you're lighter. As you're descending, the thicker air at the bottom will actually help slow you down for the same reason.
 
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captaincranky

TechSpot Addict
I thought the whole point of rockets burning up on re-entry was because of the sheer amount of fuel required to escape gravity. 700m is not escaping gravity. Then, more than double the fuel payload to ensure enough thrust for a safe descent.
You don't need more than double the amount of fuel. As you're climbing, air gets thinner and you burn fuel, meaning you encounter less resistance and you're lighter. As you're descending, the thicker air at the bottom will actually help slow you down for the same reason.
You're both somewhat right, and somewhat wrong about this

The vehicle will be a great deal lighter after attaining orbital velocity, true. However, most orbital launch vehicles are multi-stage. If this is supposed to be a single stage booster, you obviously lose payload capacity by virtue of the fuel required for re-entry braking. Still, because of lightening from burn off, the braking fuel required would be much less than the launch fuel.

However, the reason we burn up rockets instead of using them over in the first place, is simply because of the sheer quantity of fuel required to lift "X" quantity of payload.

Rocket fuels have, (at least until now ?), have a fixed energy to weight ratio, and we haven't come up with anything more energetic than liquid hydrogen mixed with liquid oxygen. Which is why they tacked that big a** tank full of that cocktail onto the space shuttle, and lit it.

And yes, the atmosphere will slow you down, and burn you up in the meantime. Google "space shuttle Columbia" if you don't believe me.

So, over the past few decades, military projects for VTOL, or STOL have been rife with huge failures. The only two salient surviving projects are the V-22 "Osprey, and the AV-8 "Harrier" jump jet (*), which incidentally uses so much fuel when vertical takeoff is required, it's effective range is less than half that of a conventional jet fighter.

So, these videos have been produced over the years, and you have to be impressed with how much money has likely been bilked out of the government by them. As to the end product, a few times it didn't even materialize. And speaking of cost overruns, The VTOL V-22 Osprey has been grounded time and again for safety issues, and I'm guessing cost maybe 4 times the original estimate.

(*)The Harrier isn't really an American effort, it's by British Aerospace industries.

For some additional reading on rocket fuels see "hydrazine" at wiki: http://en.wikipedia.org/wiki/Hydrazine Versatile stuff, they use it to make "spandex", and power rockets.
 
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