[1.0.5] Advanced Jet Engine v2.6.1 - Feb 1

[NathanKell]

Speaking of...

camlost: if you're ever bored, I'd love actually-different settings for the Avon Mk301 and the J57 (rather than just rescaled J79s), and also the Tumansky R11 (for now I'm using the J93 you made). Also maybe some really early jets like the Derwent and the Jumo 004, since rescaling the J47 obviously doesn't feel right. :]

[plausse]

3. If removing HR makes it work that's probably compatibility problem from Tweakable Everything, Throttle controlled avionics , etc.

I have (had both). And I really like them. After removing tweakable everything AJE seems to work fine. Tweakable is now history, until I find a way for them to happily coexist (remove the bits about jet engines maybe?). AJE is ace, in parity with your quick and helpful reply. Thanks!

[camlost]

@Dragon01, What do you think are appropriate? GE-90 is way bigger than 2.5m in diameter.

@NathenKell, I'm busy researching/ coding for the propeller and rotors. Could you open AJE/AJE Tester and use that .NET program I made to config something for yourself? The picture and text file should be clear enough

@plausse, you should suggest that authors of Tweakable and other mods that involves adjusting engine thrust be using a "EngineWrapper" class, in order to support MEFX and ME at the same time. You can find example from Honeyfox's EngineIgnitor or AJE's source code.

[NathanKell]

camlost: Sure, no probs. Hence the "if you're bored."

[Guest]

@Dragon01, What do you think are appropriate? GE-90 is way bigger than 2.5m in diameter.

Well, I kind of hoped for a GE-90... The real thing has a fan diameter of about 3.2m, though, making it too big. On the other hand, I don't really know of any other turbofan engines of that scale.

EDIT: Maybe a JT-9D? Or perhaps a D-18T from An-225 and An-124.

Edited April 26, 2014 by Guest

[Hodo]

So I finally figured out AJE, jet engines, and made a single stage to space plane.....

Still working on the orbit part.

But using the B9 SABRE-M and that is it, I was able to get it to mach 5.1 before and and altitude of 24-26km (Realism Overhaul with real sized Kerbin/Earth) before I had to switch to closed cycle and blow the craft to space. The trick is not burning up on climb out. It maxed out at an altitude of 141km before it began its decent back to Earth.

But I figured out with a few tests before the craft attempted to go to space.

Engine power on the SABRE and the RAMJET are based on airpressure more or less.

Using Mechjeb to read the velocity, and FAR to read the air pressure in kpa, I was able to watch the engine power change as the aircraft went higher but not faster. The air pressure dropped so the power of the engines dropped even though the aircraft never really slowed down. Once the aircraft accelerated and increased the air pressure on the front of the aircraft the power increased on the plane. Thus making it increase power, almost in some cases to the extreme. (NOTE do not put 4 SABRE-M engines on the back of something that only weighs 45tons)

[camlost]

A tip for those making SSTO under RSS: check out the specifications of Skylon on wikipedia. It weighs 300ton+ at take off and 85% of the weight is LH2 and LOx. That fuel fraction is required if you want to reach orbit speed.

I made a 150-ton SSTO with two SABRE Ms. The fuselage was made of procedural Parts, and carries 120 tonnes of fuel. 1/3 of the hydrogen was burnt in the air-breathing mode. The SABREs were just powerful enough for the take-off.

So those SABRE Ms still need buff. Multiply its "acore" by 1.5 or 2 times for yourself. I don't think that's cheating since the SABRE is only on the paper

[Hodo]

A tip for those making SSTO under RSS: check out the specifications of Skylon on wikipedia. It weighs 300ton+ at take off and 85% of the weight is LH2 and LOx. That fuel fraction is required if you want to reach orbit speed.

I made a 150-ton SSTO with two SABRE Ms. The fuselage was made of procedural Parts, and carries 120 tonnes of fuel. 1/3 of the hydrogen was burnt in the air-breathing mode. The SABREs were just powerful enough for the take-off.

So those SABRE Ms still need buff. Multiply its "acore" by 1.5 or 2 times for yourself. I don't think that's cheating since the SABRE is only on the paper

I have made 2 working SSTOs under RSS already, but none with the AJE mod. I hadn't had the time to really try till recently. Right now I am doing some test flights to see how the engines have changed what their peaks are, and how they respond at different speeds and altitudes. The biggest thing I can take from most of the air breathing jets is they overheat instantly at any speed beyond mach 4. So may have to start adding more airbrakes to my typical SSTO design just to get them to slow down enough to switch to air breathing engines.

Javascript is disabled. View full album

This is the X-4 it was the first SSTO with RSS for me.

Javascript is disabled. View full album

And this is the X-6 the second SSTO with RSS.

Both worked fine, but I needed to refine them a bit more but stopped after a few days of designing because life happened. When I got back to it I decided to give your mod a re-try, and went full realism down to the actual Earth Solar system.

[Tidus Klein]

The only thing I don't like about the sabers now is that they chug liquid fuel in closed cycle mod.

Correct me if I'm wrong but that doesn't feel right.

Shouldn't it burn more ox then fuel?

Also I found be using the b9 turbo jets to get up to speed (Mach 2.5)

And then turning them off with action groups before they blow is pretty effective.

[camlost]

The only thing I don't like about the sabers now is that they chug liquid fuel in closed cycle mod.

Correct me if I'm wrong but that doesn't feel right.

Shouldn't it burn more ox then fuel?

Also I found be using the b9 turbo jets to get up to speed (Mach 2.5)

And then turning them off with action groups before they blow is pretty effective.

Of course they use LH2+LOx, are you sure you have all mods correctly installed, including MM?

[AndreyATGB]

Is this supposed to be able to go so fast?

It easily gets Mach 1 in maybe 6-7 seconds and as you can see it maxes out at 2.7 due to overheating. This doesn't happen at high altitude.

[MAKC]

Is this supposed to be able to go so fast?

It easily gets Mach 1 in maybe 6-7 seconds and as you can see it maxes out at 2.7 due to overheating. This doesn't happen at high altitude.

I think there is a problem with AJE or a conflicting mod.

With this

@PART[B9_Engine_Jet_Turbojet3]:Final
{


@title = Soloviev D-30F6 afterburning turbofan
@mass = 2.416
@description = The Soloviev D-30F6 is a Soviet-era two-shaft low-bypass afterburning turbofan engine used in the MiG-31 interceptor. Powered by NASA EngineSim
CoMOffset = 0, 2, 0



@EFFECTS
{
@powerflame
{
@MODEL_MULTI_PARTICLE_PERSIST
{
@emission,0 = 0.0 0.0
@emission,1 = 0.6666 0.0
@emission,2 = 0.6667 0.4
@emission,3 = 1.0 1.6


}

@AUDIO
{
@volume,0 = 0.0 0.0
@volume,1 = 0.6666 1.0
volume = 0.6667, 1.2
volume = 1.0, 1.5
@pitch,0 = 0.0 0.2
@pitch,1 = 0.67 1.0
pitch = 1.0 1.0
}
}
}



@MODULE[ModuleEnginesFX]
{
!PROPELLANT[IntakeAir]{}
@PROPELLANT[LiquidFuel]
{
@name=Kerosene
}
}
@MODULE[ModuleEngines]
{
!PROPELLANT[IntakeAir]{}
@PROPELLANT[LiquidFuel]
{
@name=Kerosene
}
}

MODULE
{
name = AJEModule
IspMultiplier=1
defaultentype=2
acore=5.5
byprat=0
prat3=20
tt4=3000
tt7=6200
abflag=1
fhv=18600
eta7=0.8
tinlt=1300
tfan=1500
tcomp=2700


}

engine I can easily hit Mach 4.3 @ 23 km without the overheating bar even showing up. The engine temperature at that speed and altitude is a measly 660 degrees. Also, I'm not getting proper afterburner effects with HotRockets, the engine just glows normally.

Edited April 27, 2014 by MAKC

[Hodo]

AndreyATGB, Yeah I imagine it would accelerate fast, that is a sub 10 ton aircraft with an engine that cranks out over 200kn of thrust.

Camlost, did some more testing last night. This time on the RAMJET.

Built an aircraft that runs 2 J93s as its primary engines and 2 RAMJETs as its secondaries. Took off with all 4 engines on, the RAMJETS kicked on at .3mach as expected. Climbed to 11km altitude proceded to accelerate to mach 2.5, where I turned off the J93s, at that point the RAMJETs started to lose power and the craft began to slow down, only making it worse the RAMJETs continued to lose power till I hit .3 mach where they just turned off. If you are using ramjets on an aircraft and it is going mach 2.5 shouldnt it be going fast enough for the ramjets to generate enough power to continue to accelerate on their own at that point?

I was doing this test to see if using RAMJETs in place of SABREs is a more practical application for lower altitude acceleration of a space plane. The current issue I am having with a SSTO space plane with the Realism Overhaul and AJE is the SABREs burn WAY to much fuel just accelerating to mach 4. And they die at mach 4.5, when they should continue to make power up to mach 5, as that was the Skylons switch speed.

[camlost]

@AndreyATGB, seems your TWR is too high. First you need to bring much more fuel, as you have used 1/3 of fuel in 22 seconds. Secondly, the stretchy tanks are way lighter than any real fuselage. I recommend you add "basemass=-1" to fuesalge cfgs in RealFuel folder and use those.

@MAKC, I don't see why you're not getting the effect. I use all your mods except for timeControl.

@Hodo, The aircraft's performance is not solely based on engines. If you strap two ramjets on a B747 they will not accelerate to M2.5. The only purpose of AJE is to bring realistic engine data to the game , not to guarantee the success of certain designs. However, during my own play I find most of the RL-mock up aircrafts, with AJE and FAR, perform reasonably close to their real-life counterparts. For example to blackbird-like ramjetter in the album linked in OP was totally capable of M3.0 flight.

The SABRE TWR and isp are from the paper I linked in OP. The reason that you feel like burning too much fuel is that with out AJE, the fuel consumption calculation was wrong, by a factor of 16

Besides to Skylon is only on the paper. Who is to guarantee it will reach M5? Even if it does, I think an error of M0.5 falls into the "reasonably close" range

Edited April 27, 2014 by camlost

[Hodo]

Camlost,

I am aware of that, the aircraft is not a Boeing 747, not even close. According to the FAR and Mechjeb, it generates very little actual drag. The cd on it is low, real low, but not manned missile low.

The issue I am having is the RAMJETs are creating over 100kn of thrust at the time of switch over, which is according to MJ at a TWR of 1.01:1 for the aircraft. It should by all accounts it should continue to accerlate, but instead it starts to slow down and lose power. The aircraft is flying mostly level, with a 500mm/s rate of climb (yes that is milimeters a second). Instead of continuing to push past mach 3, it suddenly starts to lose power and slow down.

When I get home I will post pics of the craft and let you figure it out.

[Hodo]

Here is the pictures I said I would post.

I think I figured out the ramjet, but it still doesnt fell right.

Javascript is disabled. View full album

The first aircraft is a larger aircraft but should still operate quite well with the ramjet engines. Unfortunately it does not, it loses power to the ramjets as soon as I switch off the J93 jet engines.

The second aircraft is the only one that works with the Ramjet engine, but it seems to be limited at mach 4.4-4.5. I maybe able to get it to go faster if I went higher, but the engine does not produce enough power to climb under the ramjet engine alone.

[camlost]

What are you complaining about? The engines are working as intended. The "lose power" phenomenon you described is exactly what should happen. Jet engines' thrust are proportional to the gas flow through it. So whenever you climb higher the thrust decrease since you suck in less air. In stock KSP they don't lose thrust in that fashion, which is wrong and overpowering, which is the whole point of AJE.

Your heavy plane above is clearly not powerful enough to compensate its drag. I think you should try three ramjets. If you feel the drag is too much you should tell ferram4 about it really. Your light plane above however is too powerful IMO, which probably means its range is too short.

I think the ramjets and turbojets have reasonably realistic performance. It is for the players to try out different designs (What speed, altitude, range, maneuverability do you want and optimize toward it)

[NathanKell]

I have somewhat similar issues, actually; With a RATO-boosted ramjet-powered X-15-alike I got up to M5.5+ but with a similar 2x Jet, 2x ramjet aircraft as soon as I throttle back the overheating (~M2.4) I lose ground. I will keep streamlining and testing.

I did not think that my X-15alike had that much less surface drag than my twinjet, but apparently so.

(Not complaining; merely surprised at the result)

[camlost]

I have somewhat similar issues, actually; With a RATO-boosted ramjet-powered X-15-alike I got up to M5.5+ but with a similar 2x Jet, 2x ramjet aircraft as soon as I throttle back the overheating (~M2.4) I lose ground. I will keep streamlining and testing.

I did not think that my X-15alike had that much less surface drag than my twinjet, but apparently so.

(Not complaining; merely surprised at the result)

I think the after 0.13 FAR has zero drag on inlets and engines, unless there's something weird going on. Could you get some pictures and data then ask ferram4 about it? I mean the drag of engines and inlets don't show up in right-click menu so what's going on for them.

[Hodo]

What are you complaining about? The engines are working as intended. The "lose power" phenomenon you described is exactly what should happen. Jet engines' thrust are proportional to the gas flow through it. So whenever you climb higher the thrust decrease since you suck in less air. In stock KSP they don't lose thrust in that fashion, which is wrong and overpowering, which is the whole point of AJE.

Your heavy plane above is clearly not powerful enough to compensate its drag. I think you should try three ramjets. If you feel the drag is too much you should tell ferram4 about it really. Your light plane above however is too powerful IMO, which probably means its range is too short.

I think the ramjets and turbojets have reasonably realistic performance. It is for the players to try out different designs (What speed, altitude, range, maneuverability do you want and optimize toward it)

If you look through the album I posted, the 5th picture I posted, the aircraft is making 300+kn of thrust from the ramjet engines, but it is actually slowing down. When in fact it should be going faster because of the power generated by the engines.

[camlost]

If thrust>drag then aircraft accelerates, if thrust<drag then aircraft deccelerates.

[Hodo]

If thrust>drag then aircraft accelerates, if thrust<drag then aircraft deccelerates.

Thrust is greater than drag, aircraft was not accelerating, that is the problem.

Did you even bother looking at the album or are you just talking out of your fifth point of contact? I understand how aircraft work, I understand how thrust vs weight vs drag works. It is the same principle in auto racing, and I have built sub 8second in the quarter mile cars.

[ferram4]

Hodo: Thrust was not greater than drag. Since you had the FAR Flight Data window up, we can prove it.

In pic 5, the ramjets are creating 328.4 kN each, for a total thrust of 656.8 kN. As for drag:

D = Q * Cd * A

D = 218,680 Pa * 0.035 * 133.7 m²

D = 1023.3 kN

So in pic 5 you've got a 366.5 kN deficit.

In pic 6, the ramjets are creating 289.8 kN each, for a total thrust of 579.6 kN. ANd your drag:

D = 162,330 Pa * 0.035 * 133.7 m²

D = 759.6 kN

So in pic 6 you've got a 180 kN deficit.

In both cases, FAR's drag overpowers the engine's thrust and you should decelerate. I'm curious, what method were you using to calculate drag that gave you answers less than your thrust?

Whatever the case, you're flying way too low in both of those cases. Frankly, the fact that you got a plane that big up to Mach 2 at those altitudes is astounding in itself, considering the only plane of comparable size was the Concorde, and that needed to get above the altitudes you're at before it even went supersonic.

Edited April 28, 2014 by ferram4

[NathanKell]

...and ferram ninjas my half-completed math post saying the same. Well, best to be ninja'd by the master. :]

[Hodo]

Hodo: Thrust was not greater than drag. Since you had the FAR Flight Data window up, we can prove it.

In pic 5, the ramjets are creating 328.4 kN each, for a total thrust of 656.8 kN. As for drag:

D = Q * Cd * A

D = 218,680 Pa * 0.035 * 133.7 m²

D = 1023.3 kN

So in pic 5 you've got a 366.5 kN deficit.

In pic 6, the ramjets are creating 289.8 kN each, for a total thrust of 579.6 kN. ANd your drag:

D = 162,330 Pa * 0.035 * 133.7 m²

D = 759.6 kN

So in pic 6 you've got a 180 kN deficit.

In both cases, FAR's drag overpowers the engine's thrust and you should decelerate. I'm curious, what method were you using to calculate drag that gave you answers less than your thrust?

Whatever the case, you're flying way too low in both of those cases. Frankly, the fact that you got a plane that big up to Mach 2 at those altitudes is astounding in itself, considering the only plane of comparable size was the Concorde, and that needed to get above the altitudes you're at before it even went supersonic.

Awesome, good to know then MJ drag reading is off. As it said I was only generating a few hundred mm/s of drag.