The MachingBird Challenge!

[numerobis]

Where do you need landing gears?

For the takeoff

If you're not landing again, you could always put Jeb on a ladder for your speed run, save yourself the mass of the cockpit! You could also save on fuel tank mass by using an Oscar B for your final run. You should get a few m/s out of that.

Another few centimeters per second you can grab by reducing the safety margin: try 0.1% once your vertical speed is under control, or even 0.01%

[m1xte]

It shows on flight report if "someone on somecraft went EVA". So consistent flight report = no worries about cheating.

I just tested "for the lulz" if one could just hop out and push the craft into stable orbit.

Thanks to numerobis for his throttle code and for pinalollo for his intake spamming technique.

256 intake version made it to 2344m/s

http://imgur.com/a/Orjqz

I think this challenge needs only two categories

Man and the machine category for pilots

No mods, no staging and landing

Engineer and robot category for builders

Mechjeb, staging and no landing

Otherwise awesome planes and piloting just get overrun by intake spamming.

[pinolallo]

I think that we need:

Full flight speed record under 36.000 with KSC landing: flying very fast under the 36.000 need piloting (also with mechJeb), the landing back need an almost efficient plane, fuel, landing gears.

So no matter the number of intakes you are fitting if it is or if it is manned or not, you need to think about how to land back and you must safe land back with the same plane that takeoff from runaway. I hope that this will push to design matching birds that can be used and shared. This WITHOUT excluding concept planes: without free experimental craft we don't discover nothing...

Edited May 14, 2013 by pinolallo

[KinkyFerrets]

It shows on flight report if "someone on somecraft went EVA". So consistent flight report = no worries about cheating.

I just tested "for the lulz" if one could just hop out and push the craft into stable orbit.

Thanks to numerobis for his throttle code and for pinalollo for his intake spamming technique.

256 intake version made it to 2344m/s

http://imgur.com/a/Orjqz

I think this challenge needs only two categories

Man and the machine category for pilots

No mods, no staging and landing

Engineer and robot category for builders

Mechjeb, staging and no landing

Otherwise awesome planes and piloting just get overrun by intake spamming.

Not gonna lie, feeling a tad entitled here since I reached my speed with 4, reasonably placed intakes EGO BOOST, AWAAAAAAAAAAY!

[SmallChange]

Looks like Sal_Vager got the thread rating system back up and running! This thread gets a 5 in my book!

Remember to rate the good challenges!

[numerobis]

2344, awesome! I once calculated an absolute top speed around 2360 under some simplifying assumptions (engine, no fuel tank, infinite intakes), so I bet you're almost at the real limit for manned flight. A kerbal on a ladder has some mass, and every drop counts in this challenge.

I quite like the under-2km speed challenge as well; you could have challenges at various altitudes. 36km is already going to be an intake-spammy altitude: 1 intake takes you to 21 km, so 36 will require e^3 intakes (about 27) for full throttle.

[Stelith61]

Broken 2105m/s. [Mach 6 Club][stock]

^{Ignore the flameout there...}

To explain the ~70km highest point, this wasn't a ship initially designed for this challenge nor was i set out to compete when I made this flight. That's this ship's ability to fly vertically, hit 100km if I try hard enough, and then keep flying. (I made it as a stunt plane)

Album with runway shot: http://imgur.com/a/CZrpJ#0 (Note runway shot was different flight, I hadn't taken a screenie. Identical .craft files.)

The ScraperJet safely landed at 39* 8' 49" N 136* 32' 39".

.craft file here

Edited May 16, 2013 by Stelith61
forgot runway shot, in album

[Stelith61]

Second attempt, slightly faster.

Same craft, Still [stock][Mach 6 Club]

Identical on runway and in flight, same runway screenshot in album applies.

Edited May 17, 2013 by Stelith61
Second image links to larger version for more readability

[TheHengeProphet]

Stelith61, I'm impressed with those speeds, considering you are using a multi-engined craft, especially since you are just over 25 km in maximum altitude!

m1xte... you continue to baffle me. That thing is horrendously fast.

[Stelith61]

Stelith61, I'm impressed with those speeds, considering you are using a multi-engined craft, especially since you are just over 25 km in maximum altitude!

When I get up higher, I disable the outer engines with an actiongroup. But the trick isn't high altitude, it's going as fast as you can, rising at the slowest speed you can. The pressure difference between 21km and 26km isn't enough to warrant the altitude until nearing Mach 6. I have to shut off the outer engines at ~25km, and when I'm landing I use the outer engines and have the central pair running for more roll stability. If you flameout with more spaced engines you run a higher risk of losing control when spinning out.

You have to remember that this plane can get to a 75km ap as well, it's light and powerful. (But that only works pointing straight up)

[Stelith61]

If you're not landing again, you could always put Jeb on a ladder for your speed run, save yourself the mass of the cockpit! You could also save on fuel tank mass by using an Oscar B for your final run. You should get a few m/s out of that.

Another few centimeters per second you can grab by reducing the safety margin: try 0.1% once your vertical speed is under control, or even 0.01%

Landing gear has no mass, OSCAR-B's have Oxidiser (a dead weight) and they have the worst fuel-to-mass ratio of any part.

Jeb would probably be thrown of by g-forces. Can't wait until kerbal seats!

Edited May 18, 2013 by Stelith61

[numerobis]

For any fixed configuration, your top speed increases until the intakes can no longer maintain enough airflow for max throttle. Higher than that, to a first order approximation, you can maintain the same top speed at any altitude. A few effects modulate this: the Isp goes down with increasing altitude, which means you need more airflow as the air gets scarcer, which lowers your top speed -- but this is a small effect at the altitudes we're talking about: Isp is in the low 1200s no matter what, so we're talking single-digit percentages. Also, gravity goes down, which changes how well you can maintain altitude in ways that I've never carefully calculated. And throttle goes down, which means it takes longer to burn all your fuel, and it takes longer to accelerate to your top speed.

Because you can basically fly at whatever altitude you want, you can fly high enough to be where Jeb barely needs to hold on at all. A simple calculation shows that if your jet engine is pushing itself (ignore fuel tanks, intakes, and Jeb) at a steady 2340 m/s at full throttle, that means the engine is accelerating itself at 14 m/s^2, and drag is exactly counteracting it. Fly 5 km higher and the force Jeb feels on that ladder is equivalent to half his weight.

The Oscar-B has awful dry mass for its size. However, even when full, it is lighter than any empty jet fuel tank. That makes it a great choice for a record-setting run. You can drain the oxidizer on departure by setting up a small rocket engine that burns that fuel and disabling the liquid fuel. Decouple that rocket and head on your merry super-fast suicidal run.

[Stelith61]

When turning and pitching, the forces can exceed 10g, at least on some of my faster planes.

[numerobis]

You will get best results by avoiding such maneuvers when you have a kerbal holding on to a ladder.

To be clear, my proposal was that m1xte set up their plane such that Jeb gets out of the cockpit and onto a ladder once up to speed. Then decouple from the cockpit and all the fuel tanks except the single oscar. Given the current aircraft is getting 2344 with a cockpit attached and a heavy fuel tank, ditching should allow several meters per second speed improvement.

[Stelith61]

You will get best results by avoiding such maneuvers when you have a kerbal holding on to a ladder.

To be clear, my proposal was that m1xte set up their plane such that Jeb gets out of the cockpit and onto a ladder once up to speed. Then decouple from the cockpit and all the fuel tanks except the single oscar. Given the current aircraft is getting 2344 with a cockpit attached and a heavy fuel tank, ditching should allow several meters per second speed improvement.

He'd probably get slung off by wind resistance. Ever tried eva-ing when flying a plane? It's almost never ends well (in my experience).

Unless, of course, you are special agent Kirrim.

But: New personal best! 2184.4m/s. Mach 6.42. Just short of the next best. [Manned][stock][Mach 6 Club]

http://imgur.com/BSenBM6,lzTkrc8#0 High res

I'm getting good at these gliding landings.

Identical craft, but with 2 more intakes and struts. Because re-entry effects on struts look awesome.

Edited May 19, 2013 by Stelith61
corrected speed, was only 2184.4, not 2184.5

[TheHengeProphet]

Updated the speeds.

numerobis, I don't know what maths you use, but it impresses me.

I really need to get around to making a new plane to actually compete with you guys...

[numerobis]

The math is simple: when flying at top speed, your engine's thrust exactly balances drag on the airframe. Right-click on the engine to see its thrust. Divide by the mass. Bingo, you have a good approximation of the drag that Jeb will experience.

To do this without right-clicking requires knowing the thrust curve. Thrust goes from half of the engine's rating at 2 km/s down to zero at 2.4 km/s. So now we know the thrust.

In fact, I'm way off on the mass of m1xte's "plane" given I ignored the hundreds of air intakes (and the cockpit and the fuel tank). The drag Jeb would feel is far lower than what I wrote.

And then the other bit is that drag is linear in air pressure, but so is air supply, and thus throttle (and therefore thrust). So they cancel out: you can fly at any altitude at the same speed, as long as your throttle isn't maxed out. That means that if you're worried drag is too much, just fly higher -- drag will be less, and you won't lose speed.

Stelith seems convinced this is impossible, but the lightest manned lifters off Kerbin and Eve have Kerbals on ladders all the way, even in the low atmosphere.

[m1xte]

For the science.

Exploitter 2344.craft

(mechjeb removed)

I dont mind if someone makes new record with this craft or its modification. It is for the science.

edit... And skill

Not to forget numerobis throttle code and pinalollo intake spamming.

Edited May 20, 2013 by m1xte

[MR4Y]

Maybe a category without using air hogging? I know it's not possible on 0.19, but all you see is planes with a million air intakes at the first pages.

[numerobis]

I ran a vegetarian Maching bird challenge: 1 intake per engine. All of one (1) person flew in it, at just over 2100 m/s.

[Goddamnit- Clown]

http://imgur.com/a/uMMSI#3

I was messing about with Ferram Aerospace Research having just installed it when I remembered this thread, so this ended up being a manned FAR run that hit 2,208 m/s before a totally preventable flameout which i wasn't paying enough attention to prevent sent me into a spin.

Mods used only pWing (much love for pWing) and the landing gear from TT wheels. Oh, and if the plane needs a name, I christen it The Yellow Dart

[localSol]

http://imgur.com/a/uMMSI#3

I [did] a manned FAR run that hit 2,208 m/s [...] ..Mods used only pWing (much love for pWing) and the landing gear from TT wheels. Oh, and if the plane needs a name, I christen it The Yellow Dart

Can you upload the craft file? I'd like to try it too. Are they only turbojets? I didn't think FAR engines were capable of that speed..I got near it with TV's ramjets though, which are fun but they don't do much below mach speeds really and aren't allowed for this challenge. I didn't think of embedding the wing like that, maybe it makes wings more effective since the would be fuselage is treated as more of a wing. I guess you'd need part clipping or a smaller part behind to do that though?

[Pbhead]

omg. I got this. excuse me while I take my maximum airhog plane, strip off the emergency parachutes and rocket engines... oh ya. I got this good.

[Pbhead]

Hurrg. so close. 4 m/s short! Though it was a really bad run really. going to try again... and add a droptank I think.

This is all I need, right? (plus the drop tank staging if i add one)

[m1xte]

Hurrg. so close. 4 m/s short!

Try polar orbit.

My best runs usually comes when coming down from 75-90km apoapsis to 55km periapsis.

Sweet spot seems to be around 55-60km running with only 1/3 throttle. (200+ intakes)

Under 55km my craft starts losing speed.