In Dr. Martin Schweiger's freeware spaceflight simulator Orbiter 2016, a very popular(but fictional) spacecraft is the Delta-Glider.


It is capable of take-off from a runway, has hover engines for VTOL in low-g planets/moons, and lands similarly. It has several variants, including DG-S (equiped with scramjet).

Here are the major specs(table from orbiter.wiki):


Do any of the figures sound unrealistic? How feasible is this?

EDIT: It is capable of flight in the atmosphere, but is mainly designed for orbital and interplanetary spaceflight.

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    $\begingroup$ There is a close vote about your question, because it seems to like more about atmospherical flights than spaceflights. I suggest to edit it to be about spacflight. We have about aviation.stackexchange.com . I also suggest to make it more clear, "how feasible" looks too broad. How feasible for what? $\endgroup$
    – peterh
    May 27, 2019 at 20:00
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    $\begingroup$ @peterh all the questions here about helicopters or planes or gliders or ballons on Mars and Venus would then have to be considered for closure as off-topic by the same logic. I think as long as this question is specifically about atmospheric flight on Mars, a planet were so far as we know, no atmospheric flight has ever happened, it is on-topic an d should remain open. $\endgroup$
    – uhoh
    May 28, 2019 at 0:48
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    $\begingroup$ If it were feasible, NASA would have already done it. (They put a lot of research into SSTO back 15-25 years ago, but nothing came of it.) $\endgroup$
    – RonJohn
    May 28, 2019 at 5:48
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    $\begingroup$ @uhoh My votes (up + "leave open") followed the same concept. $\endgroup$
    – peterh
    May 28, 2019 at 9:18
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    $\begingroup$ My feeling as something of a regular there is that this would be quickly closed on Aviation, as a combination of too broad, off-topic and primarily opinion-based. $\endgroup$ May 28, 2019 at 9:25

2 Answers 2


The specific impulse figure of 40kN•s/kg (i.e. exhaust velocity of 40km/s) and the 31.5km/s of delta-v achieved thereby is not achievable with current propulsion technology -- it’s about 10 times the fuel efficiency of modern chemical rockets.

That performance suggests something like a fusion rocket engine.

  • 1
    $\begingroup$ Gas-core fission rockets could also get similar isps, according to Project Rho $\endgroup$
    – qazwsx
    May 28, 2019 at 14:43
  • $\begingroup$ @qazwx: Just how would this not vaporize the nozzle if there was any decent thrust? H2 propellant needs to be heated to an average temperature of ~150,000K for a 40 km/s. Ok use a "cold shield" of gas to protect the engine's walls and/or magnets. But dealing with >>10,000 times the radiant flux of the sun's surface doesn't sound easy. $\endgroup$ Feb 4, 2020 at 2:53


The extremely high Isp (about a factor of 9 above what is achievable today) enables it to perform feats of derring-do beyond our current imaginings. Apart from that, it seems feasible.


As noted by others, the Isps cited suggest a nuclear engine of some sort.
The Isp is around nine times that of the Space Shuttle main engines (!)

It has SSTO capability beyond anything we could build today.
It could "go to earth orbit" from a standing start (with tanks partially filled).
On full tanks, it cannot quite lift from the earth's surface. Even with tanks almost empty, it would be a sluggish climb to orbit for a terran launch.
But once in LEO its capabilities are astounding. Mars surface to orbit would be 'easy'.

Converting N to kg with a factor of 10 ("naughty" but makes comparisons easier)

Main engine thrust is 24,000 kg.
Empty weight + all fuel brings thrust:mass to about 1:1 but the extraordinarily high Isp allow an earth LEO delta V on well less than "a full tank".

This table shows the delta V in km/s required to go from locations in the left-hand column to locations in the top row. From Wikipedia - Delta-V budget. If you launched from earth to LEO on just enough fuel to get you there and then "tanked up" in LEO you could 'wander around' the Earth-Lunar-Lagrange environments in astounding style.

enter image description here

It gets better!

You can do Mars return from LEO on Hohmann transfer orbits with ease. And so probably greatly reduce Earth-Mars-Earth journey times with non-Hohmann trajectories.

enter image description here

But wait!
It gets better still.

You can dive into the sun! - or sun graze and just start to get back.
With full tanks from LEO you can maybe manage Jupiter or Saturn return,
easily achieve Mercury, Venus or Mars return,
And make a one-way journey to anything past Saturn.

enter image description here

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    $\begingroup$ "On full tanks it cannot quite lift from the earth's surface." -- this design is for horizontal runway takeoff, like an airplane, so it's using wing lift rather than thrust to get off the ground. $\endgroup$ May 28, 2019 at 17:19
  • $\begingroup$ @RussellBorogove Yes, I agree. I was (attempting to) address the "fact" that it is 'sold' as a 'spaeplane' but not as a planetary surface craft - as addressed in the discussion to the question re possible voting to close. On Terra the wings are "useful". On Mars, hardly at all. On Mercury, not at all. On Venus you don't want to find out :-) - but you can easily go there and back again (with or without Hobbits). I have not looked at how short an eg Mars return may be achievable pulling its max 2g each way for as long as possible on the available high Isp fuel capacity, but ... :-) $\endgroup$ May 28, 2019 at 21:57
  • $\begingroup$ All the VTC are way off base. $\endgroup$ May 28, 2019 at 22:00
  • $\begingroup$ @RussellBorogove All your base are belong ... :-). I'd be pleased for more detailed comment from you if the following is not sufficient. I assume you mean that the velocities in the table are wrong. This may well be the case - it is Wikipedia sourced after all :-) - BUT it may be that their meaning is not clear. eg in the interplanetary table "v exiting LEO" is the velocity after the single orbital burn (sufficient presumably to produce a Hohmann transfer trajectory, ... $\endgroup$ May 29, 2019 at 7:49
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    $\begingroup$ VTC = "votes to close" $\endgroup$ Jun 21, 2019 at 0:06

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