[0.22] BT Engine Pack v1.3

[Chase]

This is a simple and yet useful ScramJet engine.

On the ground and at low speeds and altitudes, slow, and it guzzles fuel like a SUV from the 90s. You're lucky you can get anything out if it. But at high speeds an altitudes it is a golden god among jet engines. It's niche, if you will, is after your other engines cease working, to push you even closer to the edge of space without needing rocket engines or air hogging. Of course you still need rocket engines to circularize, but this should be able to push you out into space.

This engine only really starts to shine once you hit Mach 4, before that it can only provide limited thrust. But once you get above Mach 4 it starts to being able to produce usable thrust, hittings its peak at 1700 m/s. But even then its not even half the thrust of the standard Jet Engine. It's real benefit lies in its ISP at high altitudes, at about 8000 meters its ISP starts to sky rocket, allowing it to function at altitudes that your other engines couldn't hope to even with 4 times the intakes.

In short, as soon as you hit about 20 km and over 1350 m/s this engine starts to be somewhat useful, you have to find some other way to get it to that point however.

The engine is far more useful at 30 km and above 1500 m/s, as this is the point most other engines start to fail on standard intakes.

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Change Log

v1.3 - Nov 4 2013, 1:02 AM

Changed name from ScramJet Engine to BT Engine Pack.

Added the Merlin 1D rocket engine.

v1.2 - Nov 2 2013, 1:26 PM

Reduced the heat values on the engine, hopefully they are more compatible with mods like Deadly Reentry.

v1.0 - Nov 2 2013, 1:55 AM

Initial Release

Licensed under a Creative Commons Attribution 3.0 License.

Edited November 4, 2013 by Chase

[sidfu]

dont forget source. i would use but since using deadly reentry crew would be dead before it be of use

[Greys]

dont forget source. i would use but since using deadly reentry crew would be dead before it be of use

It's a part, it's it's own source

[rifter]

Deadly Re-Entry wouldn't have any problems with this, since you are already well above the lower atmosphere at relatively low speeds (in terms of heat generation) when it works best...it would be kinda funny to try and use on re-entry, where you usually want to slow down; mount them in reverse since they would lose power as you lose speed = victory:D

Regardless, I really appreciate having a scramjet model though, it looks really nice. What did you base the engine stats on?

Edited November 2, 2013 by rifter

[Chase]

My modeling isn't the best, but I guess I can put up the source .mb and .psd. I also add an .obj for those who can't open a .mb file.

Regardless, I really appreciate having a scramjet model though, it looks really nice. What did you base the engine stats on?

I actually based it off from a lot of research from various sources. Wikipedia, wind tunnel tests, the information on the X-51, speculation and stats on the new SR-72. But I also tried to balance it out so it was KSP friendly, and had a niche in aircraft design, but all that came as a result of the research, not the other way around.

Edited November 2, 2013 by Chase

[DigitalSoul247]

Tried this with Deadly Reentry. Got up to 1500 m/s at about 28 km, then kicked on the scramjets at full throttle. They glowed bright yellow for a couple of seconds, then the parts they were mounted on caught fire and exploded. The atmosphere isn't the problem, the engines themselves run HOT. We may need some kind of heat radiator.

[Galacticruler]

The atmosphere isn't the problem, the engines themselves run HOT. We may need some kind of heat radiator.

Puffin Tech/Inc./Ind.(i forgot which) was working on a set of radiators, check with OrbitusII or one of those guys.

[Chase]

Tried this with Deadly Reentry. Got up to 1500 m/s at about 28 km, then kicked on the scramjets at full throttle. They glowed bright yellow for a couple of seconds, then the parts they were mounted on caught fire and exploded. The atmosphere isn't the problem, the engines themselves run HOT. We may need some kind of heat radiator.

Well they do have a warning sticker. Heh, joking aside, these do run VERY HOT (just look at the emissive). The engines themselves can handle up to 6200, but still sometimes manage to make themselves overheat.

I have found that I have absolutely no skill when trying to play with Deadly Reentry. Try changing the part config as so, and tell me if it fixes it for you.

maxTemp = 2500
heatProduction = 480

Edited November 2, 2013 by Chase

[KhaosCorp]

My modeling isn't the best, but I guess I can put up the source .mb and .psd. I also add an .obj for those who can't open a .mb file.

You dont need to do this...the person that said this has no clue what they are talking about.....your only required to post a source for plugin code...keep your model originals yours!

[s20dan]

The engines themselves can handle up to 6200, but still sometimes manage to make themselves overheat.

Depending on what units KSP actually uses, that could be hotter than the surface of the sun (Approx 5505 C)

[KhaosCorp]

KSP uses its own units for everything....and it stands to reason that these would scale down as well.

A kerbal ton 'should' be 0.64 metric tons...and so on...

Based on this logic if the engines hit 6200 that would be 3968 C...still perty damn HOT! but not straping a sun to your jet at least..until it explodes....and all sales final btw =P

[Chase]

Okay I updated it to run slightly cooler (hopefully it's emissives still work correctly). See Original Post.

[Greys]

KSP's heat system works very poorly, it's best not to mess with it, you can still have it look that hot and get an overheat bar without actually making it that hot , and then you'll suffer less of the stand-in heat system's weirdness.

[AndreyATGB]

These things seem extremely underpowered. At 30km it generates 17kN. That's so bad, it has no chance of holding the plane in the air. Velocity was about 13 000 before turbojet cutoff.

[DigitalSoul247]

These things seem extremely underpowered. At 30km it generates 17kN. That's so bad, it has no chance of holding the plane in the air. Velocity was about 13 000 before turbojet cutoff.

You need to go faster. The power really starts to ramp up around 1400 - 1500 m/s. Less than that and you should use turbojets at low throttle to prevent flameout. Once you get up to speed, the scramjets are incredibly good.

I threw together a simple plane with two ram intakes, two scramjets, and one turbojet. It was able to cruise at about 36000 m at 2000+ m/s. The speed indicator kept getting confused and switching back and forth between surface and orbital speed. Circled the planet twice in about an hour, using less than 1/3rd of my fuel. Most of that went into the turbojet for initial ascent.

I wonder how these work with FAR...

[AndreyATGB]

It goes above 20kn? It says in the VAB max power is 20 which is pretty bad. I want to use these for transport not just for fun. That means the plane is quite heavy, maybe about 15-20 tons. I'll try again soon, see how exactly they work.

[rifter]

It goes above 20kn? It says in the VAB max power is 20 which is pretty bad. I want to use these for transport not just for fun. That means the plane is quite heavy, maybe about 15-20 tons. I'll try again soon, see how exactly they work.

The max output as listed in the .cfg is 60kN, which it reaches at 1,700m/s.

[Tobyz28]

The max output as listed in the .cfg is 60kN, which it reaches at 1,700m/s.

Yup, i've been able to achieve that thrust. Playing with Far and DR. Seems to work fine, only issue is ISP goes into the negative at low altitude and the engine cuts out. It would be nice if it had a bit more thrust though, hard to warrant using this engine when i could just use another turbojet on most planes

Edited November 2, 2013 by Tobyz28

[AndreyATGB]

Yup, i've been able to achieve that thrust. Playing with Far and DR. Seems to work fine, only issue is ISP goes into the negative at low altitude and the engine cuts out. It would be nice if it had a bit more thrust though, hard to warrant using this engine when i could just use another turbojet on most planes

Even though I think it's extremely underpowered, it's much better than a turbojet when it comes to efficiency. Already at about 30km it has 4k+ ISP, that's double a turbojet which you probably can't use at that height anyway.

[Tobyz28]

Even though I think it's extremely underpowered, it's much better than a turbojet when it comes to efficiency. Already at about 30km it has 4k+ ISP, that's double a turbojet which you probably can't use at that height anyway.

Yes it's definitely more efficient. I was thinking more about the real-estate and design cost on the plane for having it... mind you I just created a pretty nice plane with these and achieved 2500m/s at 39km!

[Pigbear]

It is meant to be used in the thinner atmospheric layers where you don't have nearly as much drag make it able to go faster and output more thrust while also being efficent. and less drag also means that your plane won't fall nearly as easily.

[Chase]

Well the real thing as I read has very nice ISP but rather horrible TWR, and it needs to be going fast to be of use (Mach 4+). That and KSP limits your maximum velocity at lower altitudes, requiring me to make this a high altitude part. Which also makes sense for the real thing anyway.

The one I read about only has a TWR of about 2, where as this one has a TWR of 60, which is 30 times higher then the real thing has.

Edited November 3, 2013 by Chase

[gm537]

TWR for real life stuff is in fact Thrust to Weight Ratio not thrust to Mass thus yours has a TWR of 6.1 not 60 which while still a bit high is reasonable.

[Chase]

Ah right, I didn't consider that. So I should reduce the output to 20 kN, or increase the mass to 3?

Edited November 3, 2013 by Chase

[gm537]

Okay so been looking at this engine and while I do like it quite a bit. The problem is that at nearly all velocities the stock Turbo jets are higher thrust and they peak out at 2400m/s vs. the scramjet at 2500. There's very little advantage to carrying this with you. I would suggest upping max Thrust to 90-ish and bumping mass to maybe 3 or 4 which will make the TWR closer to the real thing (but still balanced for KSP) Also make the effective velocity range a bit wider maybe 1250m/s to 2800m/s. Those are my recommendations pick and choose.