30 replies to this topic

[Ted Wayz]

The theory behind mechwarrior jump jets is pressure released from superheated compressed gas or fluid. So why do you not lose jump jets in combat and why are there not jump jet fuel explosions?

[Juodas Varnas]

Do you WANT to make them even more rubbish than they are now?

What the hell is wrong with you?!

[Alek Ituin]

Ted Wayz, on 05 July 2015 - 08:54 AM, said:

The theory behind mechwarrior jump jets is pressure released from superheated compressed gas or fluid. So why do you not lose jump jets in combat and why are there not jump jet fuel explosions?

I always understood jump jets as being vented reactor plasma...

At least, that's what would make the most sense.

[Questia]

Because... the fuel is from the fusion reactor itself? I'm no wiki guy, but I'm somewhat sure that's how it works (thus the infinite-through-regeneration fuel supply). And besides, puncturing a fuel tank doesn't exactly make it explode, either.

Balance-wise... well, yeah. It never exploded in TT, and honestly who wants them to explode?

[Coralld]

Alek Ituin, on 05 July 2015 - 09:00 AM, said:

I always understood jump jets as being vented reactor plasma...

At least, that's what would make the most sense.

I don't know if thats true or not but I do know that's how the Flamers are suppose to work.

Edited by Coralld, 05 July 2015 - 09:03 AM.

[Alek Ituin]

Coralld, on 05 July 2015 - 09:02 AM, said:

I don't know if thats true or not but I do know that's how the Flamers are suppose to work.

I know, which is why I'm always flabbergasted by their complete uselessness. Being coated by 4.5 x 10^6 (It might be 10^7) Kelvin plasma should tear your s**t up.

[darkkterror]

Ted Wayz, on 05 July 2015 - 08:54 AM, said:

why are there not jump jet fuel explosions?

Because jump jets don't use fuel? The jump jets work by superheating air. There's no combustible fuel there, unless the Mech is using a small amount of hydrogen for use in a vacuum, but the Mech could be using water or mercury instead.

[Ted Wayz]

MWO wiki explains it as a superheated gas or fluid. Don't think it would be a good idea to be venting reactor primaries into open air.

Reactors in of themselves cannot produce thrust. That involves the use of secondary systems.

And JJ's currently go above their intent of providing limited extra mobility and the handling of difficult terrain. So JJ users are currently in bonus time as it is. Using JJ's for flight, much like being able to knock down mechs with futuristic gyros, makes no sense.

[That Dawg]

darkkterror, on 05 July 2015 - 09:06 AM, said:

Because jump jets don't use fuel? The jump jets work by superheating air. There's no combustible fuel there, unless the Mech is using a small amount of hydrogen for use in a vacuum, but the Mech could be using water or mercury instead.

True, odd they dont get damaged however, like every. other. thing.

[Goose]

The do, just rarely …

[Mad Porthos]

Being a bit of an old TT grognard and familiar with the franchise, the somewhat informed reply to the OP on this is there are several explanations for jump jets, but none of them actually use innately explosive, or flamable fuels. One of the prime explanations of jump jets that I have seen people float is that it is vented high pressure engine plasma, just like for the flamer, venting out of the jump jets, which are the individual .5, 1 or 2 ton locations where this plasma is collected and kept under pressure for when you need that kick/burst. If you think about it, with each jump jet being 1200lbs, 2400lbs or 4800lbs of weight, it's still a fairly light engine/piece of equipment to be storing a huge amount of plasma that has been vented from the reactor, under super high pressure. So why not an explosion of some sort when the JJ is taken out?

The thing is... I don't actually recall this being the prime explanation of jump jets in TT. I think it has been assumed or borrowed from the flamer explanation, as to why fuel is not carried that could explode with flamers (why no flamer napalm ammo etc.).

The actual explanation I have seen put out in TT and books is rather that the JJ are actually just that... Jets, electric powered jets. A fuel powered jet would create thrust off of the ignition of whatever flamable fuel is available, which should create expanding gas which when vented from the reaction chamber downwards makes thrust for the jump. But the electric powered jet works off of ATMOSPHERE, that surrounds the jump jet carrying mech. The immense amount of electric power generated constantly by the fusion reactor allows an arc of electricity to superheat that atmosphere that is sucked into the jump jets. Once superheated it tries to expand and does so out the BACK of the jump jets, creating thrust. But those jump jets they have to quickly spin up and compress that atmosphere into a "charge" of fuel that is to be superheated and that will burst out of the jets as thrust. They cannot do this continuously, hence JJ have a maximum charge and it takes a moment to re pressurize those reaction chambers/thrust chambers with atmosphere that will then be superheated with electricity to create thrust.

What about a vaccum, in space for instance? Well, the lore in TT says in this case, these mechs carry a limited supply of on board reaction mass, like liquid mercury or somesuch, that could instead be superheated and vented to create thrust.

Now, likely some expert in newtonian physics could point out how flawed the TT ideas are, but that's basically why JJ's don't explode. They don't have aviation fuel, they don't even have stored reactor plasma sitting around under pressure. All they have is high pressure air/atmosphere that is flash vaporized by electricity to create thrust. You would have to hit the jj right as it was arcing and vaporizing it's fuel, at which point, it would already be running and venting the thrust, so it would not explode, instead just finish venting the thrust - possibly through the hole you made as well as through the engine thrusters.

[Ted Wayz]

Now that would be cool! To see a mech get hit and then have the pressure suddenly and uncontollably fling them across the map, much like when you knock the top off a nitrogen tank!

[C E Dwyer]

OMG
Just stop using logic and Rational Engineering.

We put auto canon ammo in our feet, which means it has to get past an ankle, knee, hip, waist, shoulder, and sometimes the elbow, without Jamming, it also travels past a 'cold' fusion reactor without exploding

Get real People Jump jets are powered by My little pony Farts, thats why assault mech can barely get over an oilpipe in caustic Valley

[Strum Wealh]

Alek Ituin, on 05 July 2015 - 09:00 AM, said:

I always understood jump jets as being vented reactor plasma...

At least, that's what would make the most sense.

Coralld, on 05 July 2015 - 09:02 AM, said:

I don't know if thats true or not but I do know that's how the Flamers are suppose to work.

"However, jump jets do not add plasma vented from the fusion engine, unlike fighters. Aerospace fighters are interested in maximizing their engine efficiency because they have to carry all their reaction mass onboard, and thus want the exhaust as hot as possible. On the other hand, jump jets usually have an endless supply of reaction mass and don’t need all the complexity of venting their fusion engine’s plasma. These jets thus usually capture air as their reaction mass through a system of turbo-compressors."
- TechManual, pg. 39

"Lighting up a jet when it’s filled with incompressible water generates high pressures that rupture even the toughened jump jet’s casing. Even jump jets trying to operate on stored reaction mass don’t work right with water plugging their nozzles."
- TechManual, pg. 39

As such, there is no real need to have Jump Jets produce damaging explosions - in the vein of, say, Gauss Rifles - if critted-out.

However, I would be in favor of JJs having incremental performance decreases as they are damaged (e.g. overall theust, overall burn time, and turn rates decrease as the components' health is depleted and individual JJs are damaged prior to being completely destroyed).
This would be generally in-line with the "Expanded Critical Damage Rules" found on page 75 of Tactical Operations.

Thoughts?

[ArchMage Sparrowhawk]

Because Jumpjets are engineered to be safe and explosion free.

[EmeraldSongbird]

Nevermind I made a dumb.

Edited by Doobles, 05 July 2015 - 07:44 PM.

[El Bandito]

Ted Wayz, on 05 July 2015 - 08:54 AM, said:

Why Don't You Have Jump Jet Explosions?

Because we do not have underwater maps. JJs explode only if the JJs intake a lot of water during use.

Edited by El Bandito, 05 July 2015 - 10:11 PM.

[Mad Porthos]

Strum Wealh, on 05 July 2015 - 12:35 PM, said:

"However, jump jets do not add plasma vented from the fusion engine, unlike fighters. Aerospace fighters are interested in maximizing their engine efficiency because they have to carry all their reaction mass onboard, and thus want the exhaust as hot as possible. On the other hand, jump jets usually have an endless supply of reaction mass and don’t need all the complexity of venting their fusion engine’s plasma. These jets thus usually capture air as their reaction mass through a system of turbo-compressors."
- TechManual, pg. 39

"Lighting up a jet when it’s filled with incompressible water generates high pressures that rupture even the toughened jump jet’s casing. Even jump jets trying to operate on stored reaction mass don’t work right with water plugging their nozzles."
- TechManual, pg. 39

As such, there is no real need to have Jump Jets produce damaging explosions - in the vein of, say, Gauss Rifles - if critted-out.

However, I would be in favor of JJs having incremental performance decreases as they are damaged (e.g. overall theust, overall burn time, and turn rates decrease as the components' health is depleted and individual JJs are damaged prior to being completely destroyed).
This would be generally in-line with the "Expanded Critical Damage Rules" found on page 75 of Tactical Operations.

Thoughts?

Good to have someone with a copy of the fluff to quote, and yes, I do recall the bit about no JJ in water. Technically for this reason, people I think would locate JJ in torsos in tt, because they would not be under water when using water as cover/cooling. Regardless of that, we have jj in legs in MWO and there's no reason for or against it, simply hasn't been a worry and it would rather be a bother to make JJ explode when someone was or was not in a puddle of water, or a lake, or just on the edge, or with ONE leg with JJ in water and the other on shore. That sort of nitpicking would be a waste of game detail and design resources. Further, for the realists - who I actually need to point out just enjoy VERSIMILITUDE, the semblance of reality... it's arguable whether a little bit of water should destroy a thruster. Especially since it has been pointed out in sci-fi and a few technical forums that water itself makes a great reaction mass if you have enough electricity to vaporize it into steam as thrust. So I'd ask, do we need to get into an arguement about how jump jets are fragile enough not to contain a steam explosion, but somehow could contain the thrust of atmosphere being blasted out after itself being compressed and then superheated into a plasma by electricity? You could argue all day. Pointless as no one will have the same answer.

[bad arcade kitty]

jump jets don't use any explosives afaik, they merely use air heated by the reactor engine

btw! it means they shouldn't work on hpg manifold - no air, no reaction mass, no propulsion... unless you carry a limited supply of some gas to be heated and thrown away;

also they kind of should cool down mechs when used

[Night Thastus]

Jump jets use an electric arc to superheat air into plasma, which is then vented out of the Jet, forcing the 'Mech upwards.

"Inside a magnetically shielded reaction chamber buried deep inside the 'Mech, an electron beam superheats a reaction mass and expels the expanding gases through nozzles located on the back of the 'Mech or in its legs. Reaction mass is commonly provided in the form of air forced into the reaction chamber by a system of turbo-compressors, but most 'Mechs have a small amount of alternate reaction mass, usually in the form of hydrogen, water or mercury, in order to facilitate operation in a vacuum and to reduce the wear on the jets from superheated oxygen when in an atmosphere that contains it^[2]. The reaction mass provided by an atmosphere is effectively infinite, but the supplementary reaction mass carried on-board is limited by the number of thruster assemblies installed unless additional tankage is added to the 'Mech"

Since they are just forcing regular old air (which cannot explode) through the jet, jump jet explosions would not be possible.
End of story.