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报告翻译问题
讨论规则及指引
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The LV-N only uses liquid fuel, no oxidiser - that's where its efficiency comes from.
Fuel flow rate = thrust/Exhaust velocity = thrust/(Isp*9.81)
LV-909 "Terrier" flow rate = 60kN/(345*9.81) = 17.734kg/s (fuel and oxidiser)
LV-N "Nerv" flow rate = 60kN/(800*9.81) = 7.648kg/s (fuel only)
Burn time = qty of fuel/ fuel flow rate
FL-T800 tank, 1800kg fuel + 2200kg oxidiser
LV- 909 "Terrier" Burn time = 4000/17.73 = 226s
LV-N "Nerv" Burn time = 1800/7.648 = 235s
in an atmosphere they both suck
LV-909 Isp = 85, thrust = 14.783
LV-N Isp = 186, thrust = 13.875
LV- 909 "Terrier" Burn time = 4000/17.735 = 226s
LV-N "Nerv" Burn time = 1800/7.607 = 237s
The nerv esentialy has half the fuel since it doesnt ued an oxidiser but double the Isp so I would expect them to have roughly the same burn time.
Testing
http://steamcommunity.com/sharedfiles/filedetails/?id=487347870&fileuploadsuccess=1
Measured result matched theory +/-1s due to human clock watching
The engines are performing as described
I just wish that when you unlocked the nuclear engines they would have given you some fuel tanks to go with it. Imostly ignored aviation in my game and have no fuel only tanks as yet.
The nerv using fuel only is correct as it is based on the nuclear engine in this Scientific American article. Fission Reactor heats gas and spits it out at velocities higher than what is capable by combustion.
{链接已删除}http://$$www.mediafire.com$view$ab8xb78q2p6s51w$Electric_Propulsion_in_Space.pdf
(replace $ with \)
They give you similar DeltaV:
29 times FL-T100 (Ox+LQ) with Terrier around 6684 m/s (1305 LQ)
29 times FL-T100 (LQ only) with Nerv around 6662 m/s (1305 LQ)
3 times MK1 Liquid (LQ) with Nerv around 7445 m/s (1200 LQ)
2 times MK1 Liquid (LQ) + 3 times NCS Adapter with Nerv around 6717 m/s (1040 LQ)
THIS MEANS:
when you have less than 1305 Liquid Fuel in mixed (Ox-LQ) tanks the LV-909 Terrier is better than the Atomic Rocket
with the all-LQ tanks you need at least 1040 Liquid Fuel for the Atomic Rocket to be better than the Terrier
I have yet to unlock aircraft fuel tanks and dont use fuel mods
The title was "Is the LV-N ISP Messed Up?"
I was just showing that the Isps are as advertised, well for atmosphere at lease.
I will have to redo the test in space to confirm through experimentation that they are as advertised in vacume and thet the Nerv does have a wopping Isp of 800
Yep Terrier is more efficient when pushing small masses for exactly the reason you stipulated but for large masses you can't beat Nerv. (well you can with banks of ion) How many times are you going long distances with small masses, you need a certain amount of fuel just to get there?
Sooner or latter you will need a ∆v that is impossible for terrier. Give it infinite fuel there is a brick wall limit.
http://steamcommunity.com/sharedfiles/filedetails/?id=487455681&fileuploadsuccess=1
Also look at launch weight, The nerv is often much lighter overall and thus easier to get into orbit
I am not trying to sell you on nerv, I mix and match depending on the mission as there is no magic super engine for all purposes except in mods. Then there is VASMIR
https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket
Personally the biggest pain with nerv is that you cant asparagus it with normal rockets
Tested in space, spot on the numbers
Although I did spin jeb so fast he threw up
Or am I completely wrong in my reasoning here? I'll admit I'm not a mathematicion, not a rocket scientist.
As per the thread topic "Is the LV-N ISP Messed Up?"
I tested the specific inpulse of each engine, on the ground and in space.
Not comparing one to the other so actual fuel quantities don't matter, I just did bothe together to save time.
As for oxidiser, its not fuel per say but it is part of the reaction mass ejected out the engine.
Isp is thrust generated per unit propellant flow rate. I guess it just what the German rocket scientists chose as their definition way back when.
Anyway test showed that the LV-N's Isp is not messed up, it's Isp is 800 as per advertised in the game.
Hydrogen/Oxygen is pretty much the limit for chemical rockets when it comes to Isp, you can only get so much enegy out of the chemical reaction, only so much exaust velocity. That why they look at accelerating stuff in magnetic fields of heating it up with microwaves etc.
Hydrogen/flurine is slightly more enigetic than Hydrogen/Oxygen but no one want to deal with that stuff.
Explosives release there energy quickly and destructivly but their actual energy density is much smaller than burning fuels. Even petrol has way more energy density than nytroglicerine for example.
Better at the same number of tanks. BUT the tanks are twice as heavy and expensive for the 909. So you found the point the Nerva is better than the 909 with HALF the fuel.
The breaking point is at 18 FL-T100 + Nerva and 14 FL-T100 + LV-909 (roughly same mass and dV).
For liquid-fuel only tanks, youll need altleast 2 (1.3) mk1 fueltanks.
Because Oxidizer has mass. For chemical rockets you need two types of fuel. They both costs money and they both have mass. Thats is the reason you cant nullify the oxidizer, like you can do with intake air.
dV is depended on the mass of the full tank over the mass of the empty tank. What or how many types of fuel you use doesnt matter. Just their mass (and the ISP of the engine ofcourse).