Dom Hovering

[Forgotten Knight]

Sorry if this has already been posted, but about the Dom hovering. I would think that be a beast on gas, since it takes so much thrust to actually keep something that heavy floating, especially that close to the ground.

[Wingnut]

Seeing as the fuel it uses to make that thrust is simply air itself, it can use up all the fuel it wants to.

[Recon 5]

The Dom actually uses thermonuclear rockets according to the novels. Having said that, they should leave a trail of glass behind them as they melt the ground from all that heat...

[auriga]

However, I'd like to point out that the novels did not even set foot on earth. That description may be more applicable to the space-use Rick Dom.

[Forgotten Knight]

Seeing as the fuel it uses to make that thrust is simply air itself, it can use up all the fuel it wants to.

That's not exactly true. Jet engines use air just as a catalyst, it still requires a liquid fuel.

[Prana]

That's not exactly true. Jet engines use air just as a catalyst, it still requires a liquid fuel.

That's not eaxctly true either!

Standard jet engines use oxygen (normally from the air) as an oxidant for the combustion. Not all jets need air nor liquid fuel: i.e. solid propellant rockets.

Anyway, it is theoretically possible to have a jet propulsion using air as the propelling fluid and heating made not by combustion (but by any other kind of reaction: an example is the experimental laser-boosted rocket).

This approach is compatible (still theoretically) with the Dom using thermonuclear rockets, but it would be more complicated for the Rick Dom, since in space you don't have that fluid handy (so the Rick Dom would require some internal tanks).

Anyway I personally think the Dom hovering is one of the less believable technical feature of Gundam world.

[toysdream]

Standard jet engines use oxygen (normally from the air) as an oxidant for the combustion. Not all jets need air nor liquid fuel: i.e. solid propellant rockets.

Solid propellant rockets aren't exactly jets, are they?

Anyways, the inner workings of the Dom's jet engines were established in Gundam Century and have never really changed; this explanation is repeated even in recent sources like the Gundam Officials encyclopedia and the MG kit manuals.

-- Mark

[Laevatein]

Not all jets need air nor liquid fuel: i.e. solid propellant rockets.

Solid Propellant Rockets are not jet engines though. Their operation is simply that of a scaled-up firecracker. They're not jets that use the compression and thermal expansion of air to produce thrust. The air itself isn't just the oxidant - it is also the primary medium in which the jet engine creates the thrust necessary to propell itself.

[Prana]

Solid propellant rockets aren't exactly jets, are they?

That depends very much on what you define as Jet engine. If you mean (turbo)jet, yes it's an entirely different thing than a rocket. Jet engines are mistaken for being exclusively of the turbojet (or turbofan) type, but in principle a "jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's third law of motion."

An this definition I quote from wikipedia is not only because I read it now, but it's part of my background as an aeronautics engineer.

Thanks Mark for highlighting how the "real" Dom hovering engine is performing. Nevertheless, as for much of Gundam technology, you need a lot of suspension of disbelief to bear with it.

[deadtech]

I must come to the defense of my beloved Dom. i have always been under the impression that the Dom acted more like a Air Cushion Vehicle (or hovercraft) than something akin to a Harrier jet or the like. This observation is (retroactively) supported by the addition of what appear to be flexible skirts on the edges of the feet of the Dom Funf and Dom Tropen. Also, the same sort of skirts appear on both the feet and the gun unit of the Xamel. Which, according to this very site: "Equipped with a powerful hovercraft/hoverjet system in its legs and massive skirt armor, it could skim along the ground at high speed...". So even with the older non-skirted feet of earlier Dom models, I always assumed they were ACV, hence the big feet for greater ground coverage/lower ground pressure.

Remember also, even in the real world there are very large ACV and some that are very fast as well. So if we can suspend disbelief for big biped robots, I think ACV in some models isn't too far fetched.

Even if it is, Dom (series) is one of my fave MS designs

[domtropen]

The Dom actually uses thermonuclear rockets according to the novels. Having said that, they should leave a trail of glass behind them as they melt the ground from all that heat...

That's the problem since, according to the current tech explanation the expelled air should be extremely hot, yet I do not recall Dom burning anything by its propulsion system in animation though it make lots of cloudy dusts. Maybe it is not yet shown hovering through swamp yet...

[Dark Duel]

Well, that one jay-off Dom pilot in Lost War Chronicles does make an offhand comment about how anyone not wanting to burn to death should get away - as he was starting up his Dom.
So that seems to indicate they're hot...of course, LWC is not technically canon.

[ZeonfromHell]

The Dom actually uses thermonuclear rockets according to the novels. Having said that, they should leave a trail of glass behind them as they melt the ground from all that heat...

True, except there is more to glass than just molten sand. The whole thing in 08th team where the mega particle gun on the Apsulas left glass behind is kinda "suspended disbelief" unless UC beams have silica in them to mix with the sand; otherwise the sand would just cool and you would have a sandy-colored rock tunnel.

The same thing can go for the exhaust from a Dom's jet/rockets. Plus, although that exhaust is very hot indeed, I don't think it gets that hot. If it did, it would vaporize (or at least burn away) trees in the TV shows.

[Recon 5]

Umm... If I recall my chemistry correctly sand is composed mostly of aluminosilicates, which is why the cheapest glass, called aluminosilicate glass, is mostly melted sand.

[Gadget]

I wonder why are we worrying would the Dom's hot air fuse the sands into glass. I would be more worried that the heat will present the Dom's as an IR missile's target.

Anyway, the concept of passing hot gases through a nuclear reactor is actually a very old (as in the 60's) idea. The idea was drop as the hot gases (in the original concept was hydrogen) would be radioactive. (Nuclear fission, not fusion).

[Lans]

I think some people mistaken Rick Dom which is for space utility with the casual Dom for earth environment. They have different kind of propulsion. The Dom uses turbofan-like jet engines while Rick Dom uses thermonuclear propellant rockets. So you wont see Rick Dom with their thermonuclear rockets hovering on the earth burning grass and trees.

[toysdream]

I think some people mistaken Rick Dom which is for space utility with the casual Dom for earth environment. They have different kind of propulsion. The Dom uses turbofan-like jet engines while Rick Dom uses thermonuclear propellant rockets. So you wont see Rick Dom with their thermonuclear rockets hovering on the earth burning grass and trees.

The regular Dom uses thermonuclear jet engines. See the Gundam Century description for details.

-- Mark

[ZeonfromHell]

Umm... If I recall my chemistry correctly sand is composed mostly of aluminosilicates, which is why the cheapest glass, called aluminosilicate glass, is mostly melted sand.

My mistake, I had a Freudian slip. I meant to say sodium carbonate. That is not found in sand and has to be added in during production.

But back on topic, I still don't think a Dom's hovering system is capable of melting sand like that though. It would be too hazardus to other nearby suits, and we never see a big glowing orange trail in the anime or in manga or in games (even if games are notg cannon).

[toysdream]

My mistake, I had a Freudian slip. I meant to say sodium carbonate. That is not found in sand and has to be added in during production.

Now you're just nitpicking. It's well-known that, because sand is mostly silica, it melts into a glassy substance when exposed to intense heat; the same thing happened during the first nuclear tests. You wouldn't use it for your windows, but that's hardly the point.

Getting back on topic: I don't think the exhaust from a Dom's jet engines would really melt the ground beneath it, since the superheated hydrogen cools rapidly as it mixes with air. (The actual exhaust consists mostly of air, with the hydrogen serving mainly as a heat transfer medium.) But it would still be very hot - hotter than a conventional jet engine - and I certainly wouldn't want to stand near it!

-- Mark

[Forgotten Knight]

Getting back on topic: I don't think the exhaust from a Dom's jet engines would really melt the ground beneath it, since the superheated hydrogen cools rapidly as it mixes with air. (The actual exhaust consists mostly of air, with the hydrogen serving mainly as a heat transfer medium.) But it would still be very hot - hotter than a conventional jet engine - and I certainly wouldn't want to stand near it!

-- Mark

No that might hurt a bit.