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Originally this question asked about using blimps and electricity in replacement of boosters. As written then it was no good and got down votes. I had a few question marks and each question really needed there own question. I have split up the question into other questions and apologize if your answer does not perfectly align with this question anymore. I hope this is a better question? Below in the links are questions pertaining to this one. Thanks and Enjoy.

In the picture below the Stratolaunch plane is towing a rocket in place of using stages. Could the Stratolaunch Plane shown belowenter image description here be replaced with a wing shaped blimp with an electric turbine make a launch stage that would follow a floating electric power line?

enter image description here

https://aviation.stackexchange.com/questions/31370/could-a-plane-with-an-electric-turbine-engine-generate-enough-lift-as-an-alterna

https://worldbuilding.stackexchange.com/questions/88075/sky-train-blimp-plane

https://robotics.stackexchange.com/questions/11449/can-high-voltage-power-lines-provide-a-super-highway-for-drones

Would a balloon pop if dropped from space?

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    $\begingroup$ @Muze. the issue is not only the size, it's also the weight. A blimp large enough to hold a ROCKET would be incredibly heavy. And you would need to carry all that weight to mars. $\endgroup$ – Antzi Dec 5 '16 at 3:42
  • $\begingroup$ @Muze, Do you want to know about landing on Mars, or on Earth? Or would the blimp be used during the launch on Earth? The question seems to mix all of these. $\endgroup$ – Hobbes Dec 5 '16 at 15:24
  • $\begingroup$ The current answers are not out of date. There are no recent events that would change physics to make this possible or useful. $\endgroup$ – Rory Alsop Jan 10 at 9:00
  • $\begingroup$ The existing answer(s) talk about Mars. It appears you have significantly altered the question since they were written. $\endgroup$ – Organic Marble Jan 10 at 13:20
  • $\begingroup$ @OrganicMarble This question is less chaotic then before. It had to many questions and I have divided the questions into new ones. I wish it could be deleted altogether . $\endgroup$ – Muze Jan 10 at 13:32
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Using a blimp for takeoff is pointless.

The hard part of going to space is not the distance you travel to get out of the atmosphere. It is the speed. To get to space and stay there, you need to travel at 28,000 km/h. Once you have a vehicle capable of doing that, making it travel 200 km upwards is trivial.
Using a balloon doesn't save fuel, it doesn't make the launch easier and it doesn't make the rocket cheaper or easier to build.

You also can't just add rocket engines to a blimp. A rocket engine generates a huge amount of thrust (to get to 28,000 km/h in a reasonable amount of time), and no balloon is built to withstand this acceleration so the balloon would collapse.

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    $\begingroup$ Any atmosphere dense enough to provide buoyancy provides enough friction to burn up a large, thin structure like a balloon. $\endgroup$ – Hobbes Dec 5 '16 at 16:35
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    $\begingroup$ @Muze You don't have time to wait to accelerate because of gravity drag (google it). Any second spent under orbital speed equals to a loss of 9.8m/s of delta v. $\endgroup$ – Antzi Dec 5 '16 at 16:36
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    $\begingroup$ You don't get anything for free. What you will gain in buoyancy you loose in drag. What you gain in lift you lose in drag. $\endgroup$ – Antzi Dec 5 '16 at 17:39
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    $\begingroup$ Honestly forget about the blimp. To have any effect you need a volume so huge that it is impossible to make it move fast. You cannot harden it because it would make it too heavy. $\endgroup$ – Antzi Dec 5 '16 at 17:44
  • $\begingroup$ @Antzi not at 50+ km in altitude it could behave like a rocket. In an ideal gas/atmosphere the blimp can dump its air breathing fusion reaction engines and launch? $\endgroup$ – Muze Jan 9 at 15:15
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Context

Mars density is less than 1% of earth's. This is what earth looks like from 30 000 meters high (where air is about as dense as Mars)

enter image description here

It's going to be too heavy

Using this book as a reference, we can see that to lift 1T to 30 000m we need a 10T balloon (accounting for balloon and lifting gazes).

Of course you'll need more since you'll want to produce positive lift before touching the ground.

An empty (without payload and fuel) Ariane 5 is 50T.

To lift it to 30 000m, the blimp + rocket would be already 500T!

Now that you are at 30 000m, you need to accelerate the whole 500T by 13 500km/h just to reach mars (And I'm not even counting any deceleration).

In order to do that, you would need an incredible amount of fuel, that would in turn increase the mass of your blimp, making the whole thing unsustainable due to tyranny of the rocket equation.

To go to space, you don't need to get really high, you only need to get really fast.

It would not survive reentry

Assuming that you succeeded to sent your blimp to mars (no, you did'nt), you are moving at a an incredibly high speed.

As a reference, the heat shield for the mars exploration rover was 78kg for a 1T payload. To survive the aerodynamic forces (>15G for curiosity), you would need a really strong structure, which can only translate to more mass, which translate to even more mass when the blimp and rocket equations are factored.

Conclusion:

It is impractical because

  • The blimp itself would be much too heavy
  • Mars atmosphere is much too thin
  • It offers no advantage compare to a rocket

And that's using very optimistic numbers and discounting many factors who would, by themselves make it fail.

When mass is a premium, you don't want to carry around a heavy blimp.

In orbit, your mass is still the same as it was on earth, and a the blimp that initially lifted you up of the atmosphere is actually heavy.

Tl;dnR

No.

How big would be a blimp if you wanted to lift at 1atm ?

Since your title question seems to be slightly different, let's try to answer it.

The Hindenburg could lift 10 000kg for a volume of 200 000m3. A falcon 9 fully fuelled is 750 000kg.

Therefor you need 200000/10000*750000 = 15 000 000 m3 to lift the rocket. the cruise altitude was 200m, so don't expect going much higher than that.

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    $\begingroup$ One of the largest blimp (the Hindenburg) we ever made had a 200000m3 capacity. Only the lifting gas (h2) weighted over 16 tonnes. This is vastly insuffisant for your rocket, and already more than the capacity of our heaviest rockets today (~4T). What part exactly do you think is wrong? $\endgroup$ – Antzi Dec 5 '16 at 8:51
  • $\begingroup$ I have revised my question. Your answer may be slightly off. Sorry $\endgroup$ – Muze Feb 4 '18 at 20:33
  • $\begingroup$ You are trying to solve an exponential equation using linear patches. $\endgroup$ – Antzi Feb 5 '18 at 0:22
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    $\begingroup$ +1 "Tl;dnR" ;-) $\endgroup$ – uhoh Jan 9 at 6:08
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    $\begingroup$ @Muze you have two answers, so you really should not change the question. This idea of getting some answers and then revising your idea is not the right way to use Stack Exchange, even though it is convenient for you. $\endgroup$ – uhoh Jan 9 at 15:42

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