This question is similar to my previous ones but configuration is different and so is the question.

Could a modified electric turbine engine (E-Fan) plane create enough of its own lift not to burden an electric rail that is evenly supported by electric powered blimps and rail (similar to a 3rd rail of a train) while carrying a payload (like the space shuttle) to the edge of space? The problem with a high power electric engine is the is the supply of electricity and weight of the engine and battery . The blimps and rail are necessary to provide the amount needed without a huge battery. Rockets still can be used at the end of it.

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    $\begingroup$ I personally see this as being aviation related because the vast majority of the answer involves objects that are in the atmosphere, and could be considered aviation related (space is just the destination.) That being said, I worry the scope of the question is too broad. I would encourage the OP to take a closer look at the idea and see if there are individual pieces you could ask questions about, rather than throwing one huge idea onto the stack here... $\endgroup$ – Jay Carr Sep 9 '16 at 0:29
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    $\begingroup$ @RalphJ as a matter of fact, it has been crossposted :( $\endgroup$ – Antzi Sep 9 '16 at 4:07
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    $\begingroup$ The fundamental misconception is, to put something into orbit, most of the energy you need is to generate speed not altitude. So even if you are lifting the payload into orbit altitude cheaply, you only made less than 10% of the problem cheap. $\endgroup$ – user3528438 Aug 14 '17 at 13:49
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    $\begingroup$ You might also want to consider transmitting the power to the electric aircraft wirelessly, like microwaves. Simpler, and much more robust. One reason lighter than air ships are rarely built is vulnerability to storms. In the 1920's and 1930's, three major airships: the British R101 and US Navy Akron and Macon, crashed due to encountering storms. . $\endgroup$ – tj1000 Aug 14 '17 at 22:38
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    $\begingroup$ Please avoid heavily editing your question after it has been answered, it is not respectful towards the people putting effort in answering your questions. $\endgroup$ – Federico Feb 7 '18 at 15:03

Assuming maximum altitude for the highest blimp is 74,000 feet, and the rail to be angled at 15 degrees, it gives us a rail length of 285,000 feet. The HiSentinel stratospheric airship flew that high, and was able to carry only 36 kg.

The steel rail/rope would weigh roughly 5.5 million kg. Based on steel density and a good sized rope, to withstand the elements. So we'll need 154,000 blimps to carry the rail. That's 1 blimp every 2 meters. Blimps are huge.

While the idea is highly imaginative (good thing), engineering tends to solve problems, not create ones. Would the blimps (if they fit in the sky) power down between launches? Or stay aloft?

You might want to check out the Stargazer:

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[A] Lockheed L-1011 TriStar that was modified to be used as a mother ship launch pad for Pegasus rockets. As of June 2012, 35 rockets have been launched from it.

RE: How much lift could an electric engine powered plane provide if the power source was provided externally?

What you are asking is like having a plane not carry fuel and instead have a long fuel hose attached to a fuel pump on the ground. Ignoring all the problems associated with that, one will help you understand the problem: pumping the fuel.

Pumping electricity over such a long wire / rail will require high voltage / low current (just like power lines). Which means the E-Fan-like plane and all the blimps will need to carry their own super heavy transformers (as I wrote above, one high-altitude blimp lifts 36 kg, which we've already used for lifting the rail).

  • $\begingroup$ @Jen magnetic power generators like the ones in nuclear plants ? $\endgroup$ – Antzi Sep 9 '16 at 7:10
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    $\begingroup$ @ymb1: Tanks for cryogenic liquids are insulated with foams that require an exceptional authorization of use because they are (or produce) CFC (which are banned to protect the ozone layer). LOX is often produced by electrolysis, hence by converting electricity, and I won't mention solid boosters... So I wouldn't swear rocket engines are very clean either :-( $\endgroup$ – mins Sep 9 '16 at 9:08
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    $\begingroup$ +1 for "engineering tends to solve problems, not create ones", but also the rest, too. I propose to use aluminium for the rail, but that only mitigates the problem and doesn't solve it. $\endgroup$ – Peter Kämpf Nov 5 '17 at 20:19
  • $\begingroup$ Muze is right, they would not carry transformers. In fact applications similar to this already use high voltages for (AFAIK) the same reasons high voltages are used for power lines. $\endgroup$ – Ville Niemi Feb 14 '18 at 21:43

A basic problem you have with this design is weather - what do you do when a storm passes through? Due to their large surface area, your blimps at lower altitudes are going to be pushed around a lot by high winds, probably to destruction.

Storms, and the associated high winds, can extend upwards of 40k feet, in extreme cases.

You might think about getting the electricity to the aircraft by other means, perhaps microwave transmission.

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    $\begingroup$ So are you saying that you keep the entire fleet of blimps on the ground until you launch? Going to take a while to get all of them in position, and storms have been known to appear within a day. $\endgroup$ – tj1000 Nov 30 '17 at 16:04
  • $\begingroup$ You still a member? $\endgroup$ – Muze Sep 28 '18 at 1:07

Well, its going to be a question, not if one could do that, but whether it makes more sense to use a simpler system such as Paul Allen's StratoLaunch or Orbital's Stargazer / Pegasus systems.

First, let's ask ourselves why design an all electric powered aircraft to provide a mother ship for launching rocket payloads into orbit or beyond?

The primary advantages of a reusable mothership/daughtercraft runway to orbit system is it allows you to take advantage of the air in the atmosphere to boost your payloads through the lower layers of the atmosphere by using the existing air as a working fluid as well as making use of atmospheric oxygen to oxidize chemical propellants, reducing the need for large rocket engine and boosters to clear the lower atmosphere, greatly saving the amount of money it costs to launch a unit mass into orbit.

Adding an electric propulsion system potentially can create a more environmentally friendly launch system, depending on the methods used to generate the electricity to power the craft.

So supposing we use an all electric version of Allen's Stratolaunch system. It's powered by six PW4000 engines, each with a specific fuel consumption of 0.583 lb per hour / lb thrust. With the engines producing 56,750 lb thrust, this gives us a fuel consumption rate of 6 x 56,750 x 0.591 = 90,232 kg/hr of JET-A fuel. Typically for an electric motor, their power consumption is roughly 1/3 of that of a hydrocarbon engine per unit of mechanical power out of the driveshaft. Given this fact, assuming any a 100% efficiency for propellers and/or fans, as well as the energy density of JET-A fuel is approx 45 MJ, an electric aircraft of this type would be consuming about 1.35E12 J/hr = 376 megawatts of electric power to haul this kind of an aircraft and payload into launch position at high altitudes.

Typically electric power is transmitted by means of high voltage lines, operating in the 250,000 - 500,000 AC volt range. Assuming these lines and load offer a zero impedance load, this requires these lines transmit a 750 - 1500 amps of current to carry that kind of power. Typically Aluminium-conductor steel-reinforced cable heavy enough to carry that kind of power weight about 800 lbs per 1000 ft of cable. Using this and not taking into account for the additional structure needed to support and separate the lines to prevent flashover arcs and system failure, we will need a lifting system which can support approx 8000 lbs per mile of power lines needed (remember we need at least two lines). Assuming we use helium balloons to support these lines and helium has a lifting capacity of 14.49 cu ft per pound lifted, we will need balloons of approx 115,920 cu ft per mile of lines needed. This is roughly on par with a Goodyear sized blimp on each mile marker to support this system.

Another problem with balloons supporting the lines is there is no way to prevent the balloons from drifting together under the weight of the lines sagging, further defeating any effort to suspend the lines at altitude.

And this doesn't even begin to take into account for the problems of departing and maintaining contact with the line throughout the flight, effects of weather on the lines, servicing and maintenance, etc.

Bottom line, a scheme like this is physically feasible but its excessively complicated and expensive when there are far simpler alternatives for this kind of a space transport system.

Honestly with a complex design like this, you would be far better off simply launching the rocket and payload aloft under a helium balloon (it would have to be really big!), letting it reach 100,000 or so feet then releasing and igniting the rocket on its final flight into orbit. But even that is far less feasible then a hydrocarbon powered mothership. If you’re searching for a more environmentally friendly solution, I’d consider a Stratolaunch fueled using biodiesel. It would be a zero net carbon solution and would work well here. Abandon a crazy scheme like a sky rail; back of the envelope calculations just show it’s not feasible.

  • $\begingroup$ Outstanding.... It would make contact like a high speed monorail without the burden of having to support the weight. Would a nuclear reactor be able to power it or a solar grid? Cleaner? $\endgroup$ – Muze Sep 23 '18 at 4:39
  • $\begingroup$ Again, you can generate the electricity using nuclear power, but again you are faced with the problem of how to transmit this from a ground station to the aircraft itself. Nuclear powered aircraft have been examined by both the US and USSR in the 50s and 60s but found to be infeasible due to the radiation danger the reactor posed to the crew. $\endgroup$ – Carlo Felicione Sep 23 '18 at 4:41
  • $\begingroup$ The nuclear station is at the base of the tower not on the plane. The plane has no battery and if in a aborting god forbid the blimps would have plenty of surface area to act as a parachute but not without damage to the tower. $\endgroup$ – Muze Sep 23 '18 at 4:42
  • $\begingroup$ a tower on the ground or one which is held aloft by balloons? $\endgroup$ – Carlo Felicione Sep 23 '18 at 4:43
  • $\begingroup$ Well if you place it aloft using tethered balloons, that’s a whole new kettle fish, nuclear plants are quite heavy. As a yardstick the A4W pressurized water reactors on a Nimitz Class aircraft carrier weight several hundred tonnes each, not counting the weight of the power plant itself. That will require an balloon of 26,000 cu ft per ton lifted. Clearly this is not feasible. $\endgroup$ – Carlo Felicione Sep 23 '18 at 5:08

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