The MachingBird Challenge!

[clapanse]

I present the Hopeless Triangle Thing:

https://www.dropbox.com/s/4cygnjzfksaqm0k/OnRunway_1inlet.PNG

It's pretty much impossible to fly by hand, so only MechJeb makes it possible, but it will do 2 km/s on completely stock parts (aside from MechJeb) with only one engine and one inlet. It makes a pretty nice fireball too...

https://www.dropbox.com/s/t8rg9do2q8odzhq/inflight_1inlet.PNG

https://www.dropbox.com/s/d88iinknomqo8ic/flight_summary_1inlet.PNG

Sadly, it's about 25 m/s short of the mach 6 club - I may try to squeeze a bit more performance out of it at some point, but it's not too bad for now...

Edited May 7, 2013 by clapanse

[TheHengeProphet]

Awesome entries, everybody! Sorry for the delay, I've been having some serious internet issues at home.

occar, you could probably improve your speed a bit by making sure that all of your intakes are facing directly forward, otherwise they just cause drag without allowing full benefit.

[longbyte1]

Challenge accepted...

I was somewhat inspired by the air intake abuse and made a bit smaller plane.

Pics are here: http://postimg.org/gallery/zli5wpq/

On runway:

Max speed (2296.5 m/s indicated, 2287 m/s on post-flight, beating clapanse and soo cloose to beating pinolallo):

Landing (out of fuel):

In SPH:

Some of you may be asking what that thing on the bottom is for. It's just a booster to raise the jet a few meters above the ground so that it can perform a more nominal takeoff. I guess you can take off without it, but that would involve skidding across the runway, and I haven't tried it out.

No .craft file yet!

Edited May 7, 2013 by longbyte1

[occar]

occar, you could probably improve your speed a bit by making sure that all of your intakes are facing directly forward, otherwise they just cause drag without allowing full benefit.

I'm actually trying a more sane design that doesn't use quite so many intakes. I don't know if it's feasible though. It has no real wings, other than the wing connector things, and some winglets.

I'm letting mechjeb fly it. So far, it has only gotten up to 2232 m/s, so it's not looking good.

edit: yup, the only way to do this is as many intakes as possible. doh. new model. It's scary looking, but you have to have a lot of surface area if you aren't part clipping to fit those things on. The thing is the most unstable plane I've managed to get up in the air before... Mechjeb only here.

Edited May 8, 2013 by occar

[pinolallo]

MechJeb manned

Another try (this has a name: drakken)

2.303

(but the flight was for the highest periapsis challenge.

click to enlarge

(I did the max speed at 5 min after takeoff, i guess this bird can do better than this with less fuel on board)

I do love this bird that is amazing maneuverable.

[clapanse]

Here's a 2288m/s manned plane, all stock except for MechJeb (kind of a basic, generic, high-speed design). It could probably do 2300+, but I'm not patient enough.

https://www.dropbox.com/s/mykcialhhltuxfn/2288_takeoff.PNG

https://www.dropbox.com/s/fmuuwv47f0c0ys4/2288_inflight.PNG

https://www.dropbox.com/s/4ihpholzwepnuum/2288_summary.PNG

Also, I took a look in the config files, and I'm pretty sure mach 7+ is not possible. This bit of code is in the part.cfg file for the turbojet:

velocityCurve

{

key = 0 0.5 0 0

key = 1000 1 0 0

key = 2000 0.5 0 0

key = 2400 0 0 0

}

I would tend to interpret that as stating that the engine makes 0 thrust at 2400 m/s (relative to atmosphere), which is somewhat corroborated by the seeming upper limit of 2300 and a bit seen in the results above.

Edited May 8, 2013 by clapanse

[clapanse]

Yep - that's definitely the right config file and data. I tweaked it as shown here:

velocityCurve

{

key = 0 0.5 0 0

key = 2000 1 0 0

key = 3000 0.5 0 0

key = 3400 0 0 0

}

And this was the result:

https://www.dropbox.com/s/x0lk0opl3wrutuk/cfg_edit.PNG

(No other changes from the previous post were made, and that is exactly the same craft)

Actually, given that the hard upper limit in stock KSP is definitely 2400, some of the results are impressively close to the maximum.

[occar]

No one has come within 60 m/s of that point anyway, so....

My second design monstrosity ended up with nearly the same speed as my first, so I'm not sure. It may not be possible to get much more than in the 2320s with a manned ship, and 2330s with a pod.

[TheHengeProphet]

Yes, it is not possible to reach 2402 m/s on jets alone, and this saddens me. I'll try to get around to updating the boards. What I am really curious about is how engines measure speed, as in which measurement do they use?

longbyte1, I'm sorry to inform you that your take-off mechanism disqualifies it from having a horizontal liftoff AND jet-only use. I'm sure it can take off in skid-mode, but you need to be sure not to pull up before the runway ends (yes, you need to go off the end for that to work).

[m1xte]

Ok i upload my old craft. It goes to the manned stock category.

I think i call it the exploitter.

2336m/s

Takeoff

Staging

Report

Pictures are from three different flights.

Does it gualify or should i start grinding the top atmosphere again?

[TheHengeProphet]

I remember that thing!

Anyways, the first picture is mainly there to prove the plane can make a horizontal take-off, and while I would prefer all pictures are from the same flight, I'll make an exception here.

No one has come within 60 m/s of that point anyway, so....

My second design monstrosity ended up with nearly the same speed as my first, so I'm not sure. It may not be possible to get much more than in the 2320s with a manned ship, and 2330s with a pod.

If you look at the old leaderboard, you'll see my top speed was 2332 m/s, which was in a manned craft. I got 2330 in it the other day, again, but I guess I forgot to screenshot the flight record, so it looks I'll be flying it again.

Edited May 11, 2013 by TheHengeProphet

[m1xte]

I'll be flying it again.

Be carefuf. The challenge is getting hotter in .19.

[KinkyFerrets]

In .19, manned, jet fuel only. Second screenshot is of gear jettison. It ejects so fast I was worried I wouldnt capture the gear in the shot XD.

I guess its called Weight Stripper. (Obsessive drag and weight reduction. I have another version that looks much prettier )

http://imgur.com/a/z8Bsu#0

[numerobis]

I take it you believe the SPH that says that gear has mass -- but actually it's weightless.

[KinkyFerrets]

I take it you believe the SPH that says that gear has mass -- but actually it's weightless.

Huh. Weird, since its placement affects the CoG according to the marker, and has a noticeable difference in flight...

[TheHengeProphet]

When the gear is open, it has weight, but that goes down to zero when it is closed. This is to simulate drag caused by open gear, but they had to do it this way because of how drag is simulated.

[KinkyFerrets]

When the gear is open, it has weight, but that goes down to zero when it is closed. This is to simulate drag caused by open gear, but they had to do it this way because of how drag is simulated.

Ah, that makes more sense. Thank you.

[Nao]

When the gear is open, it has weight, but that goes down to zero when it is closed. This is to simulate drag caused by open gear, but they had to do it this way because of how drag is simulated.

From what i know "small gear bay" don't have mass as well as drag in both open and closed configurations. The mass is shown in VAB and moves CoG there, but it isn't used in flight. That means the true CoG in flight isn't in the place indicated by VAB CoG.

Also while building some small ships i noticed that the gear bay does add it's mass to rotational inertia calculations. (can be wrong on that one thou)

edit: forgot to congratulate m1xte for his awesome manned 2336m/s. Nice job!

Edited May 12, 2013 by Nao

[m1xte]

I bolted mecjeb v2 in to the upgraded exploitter.

2340m/s modded manned

Getting ready

Chariots of fire. Set course 315

Staging is always exiting event with this craft.

More staging.

Result

[Nao]

LoL, nice! How many intakes is this ?

There is no way i'm using this much but i have an idea on how to beat that (done 2343m/s manned in testing) but it will take a while before i succeed with an actual mission.

Anyways, Kudos!

edit: as always im dumb there is a resource tab ... 192 intakes, hmm lower than expected.

Edited May 12, 2013 by Nao

[clapanse]

Yes, it is not possible to reach 2402 m/s on jets alone, and this saddens me. I'll try to get around to updating the boards. What I am really curious about is how engines measure speed, as in which measurement do they use?

From what I can tell, based on some experiments with prograde, retrograde, and polar flight paths with high speed jets, the engines really only care about speed relative to the air, and it doesn't seem that there are any high altitude winds (so basically, relative to the ground). Going retrograde makes it a bit easier to avoid accidentally going into orbit, but it also means you have to stay in the lower atmosphere, since you have to make more of the lift yourself, and I wasn't able to get any more speed going retrograde as compared to prograde.

[KinkyFerrets]

http://imgur.com/a/Ibl1R#0

Weight Stripper MKII

2188m/s with a drop tank release stage.

[m1xte]

FASSSSTERRRRR GODDDDDDDDDDDDDDDDDDAMMMIT!!!!!!!!!!!!!!!

Where do you need landing gears?

For the takeoff

[SmallChange]

Got an entry for the stock manned category.

No mods were used, only mod I have installed is SubAssembly.

Looks like I topped out at 2,209m/s. I'd never had anything close to this degree of success with a plane before! Dang things are tricky!

If I missed or forgot something, lemme know!

[TheHengeProphet]

Awesome entries folks!

I just have to say... m1xte... what? That thing is horrifying!

On a side note, I want to figure out how many intakes before it becomes too many intakes.

Also... I hate that it technically isn't provable (particularly if the person crashes) whether or not someone got out and pushed while on a sub-orbital hop, but would like to express that it is against the rules. Humorous, however it may be.