Ion glider collier trophy!

[GoSlash27]

Just to clarify on this challenge, would a run with Kerbal Engineer Redux installed for performance monitoring be acceptable?

Viragos,

Any mod which does not alter the performance of the stock parts or physics would be fair game. So long as your craft *could* be constructed and flown in a 100% stock installation with 100% stock parts and get the same result, you're good to go.

Best,

-Slashy

[Viragos]

Cheers, thanks for the reply

[The_Rocketeer]

I've had some fun trying to beat this challenge, but here are the cold hard facts:

All wing parts have the same drag (0.02), so the best wing for the challenge is the one with the highest lift:mass ratio.

These are the best 2 wings:

Delta Wing

Lift : 2

Mass : 0.1

Lift:Mass : 20:1

Swept Wing

Lift :1.6

Mass : 0.05

Lift:Mass : 32:1

(I know which I'd pick).

At 46,000m the atmospheric pressure drops below 0.0001 atmospheres. That means at an equivalent airspeed and angle of attack, those wings are producing less than 1 10,000th of their lift force at sea level. In other words, they're dead weight.

The 2kn PB-ION engine can't lift it's own weight (let alone fuel, wings and probe core/pilot) until it's at an altitude in the precise region of 50,000m.

To reach 50,000m, at a downright optimistic climb-rate of 25m/s (I don't think I've ever sustainably climbed faster than this in an ion glider, at least as high as 25,000m) you would need to keep flying for over 30 minutes. For a single PB-ION engine at full throttle, that would require almost 1000 Xenon, or 1 PB-X150 and 1 PB-X50R. Remember this isn't counting what you need to make the last 20,000m. Adding more tanks adds more deadweight, pushing that 50,000m mark ever higher (in practice at a guess I'd say about 53,000m just allowing for the mass of empty-ish tanks and a pair of wings).

I'm NOT saying this challenge is impossible (although I leave that door wide open for a better mathematician), but I am saying it is at best torturous. Even with autopilot mods it would still take an incredibly tenacious soul to stick at it long enough to near success.

It goes without saying that I will applaud the loudest of anybody when someone manages to pull it off.

Edited November 4, 2014 by The_Rocketeer

[GoSlash27]

I've had some fun trying to beat this challenge, but here are the cold hard facts:

All wing parts have the same drag (0.02), so the best wing for the challenge is the one with the highest lift:mass ratio.

These are the best 2 wings:

Delta Wing

Lift : 2

Mass : 0.1

Lift:Mass : 20:1

Swept Wing

Lift :1.6

Mass : 0.05

Lift:Mass : 32:1

(I know which I'd pick).

At 46,000m the atmospheric pressure drops below 0.0001 atmospheres. That means at an equivalent airspeed and angle of attack, those wings are producing less than 1 10,000th of their lift force at sea level. In other words, they're dead weight.

The 2kn PB-ION engine can't lift it's own weight (let alone fuel, wings and probe core/pilot) until it's at an altitude in the precise region of 50,000m.

To reach 50,000m, at a downright optimistic climb-rate of 25m/s (I don't think I've ever sustainably climbed faster than this in an ion glider, at least as high as 25,000m) you would need to keep flying for over 30 minutes. For a single PB-ION engine at full throttle, that would require almost 1000 Xenon, or 1 PB-X150 and 1 PB-X50R. Remember this isn't counting what you need to make the last 20,000m. Adding more tanks adds more deadweight, pushing that 50,000m mark ever higher (in practice at a guess I'd say about 53,000m just allowing for the mass of empty-ish tanks and a pair of wings).

I'm NOT saying this challenge is impossible (although I leave that door wide open for a better mathematician), but I am saying it is at best torturous. Even with autopilot mods it would still take an incredibly tenacious soul to stick at it long enough to near success.

It goes without saying that I will applaud the loudest of anybody when someone manages to pull it off.

Rocketeer,

Actually, the wings do not have the same drag. They have unique induced drag numbers as well as parasitic drag and the induced drag is a quadratic function of speed. The swept wing was clearly the way to go in .24, but...

This is complicated by the new offerings from the .25 update, which contains some wings that look very promising on paper (hint, hint)...

The Kollier trophy challenge is almost completely an engineering exercise. All the exciting stuff happens before the plane is placed on the runway, and the actual flying is about as interesting as watching paint dry.

Right now, the competition is just to be the highest and fastest. But speaking from experience, it's not a linear slog to orbit. The first 10 km takes forever with seemingly no gain other than altitude. Then 25 km happens in the blink of an eye and you're going so quick you have stability issues. 25-30 KM is like a wall, where you are seemingly unable to gain any more speed or altitude. If you get north of 35 km, you're almost assured orbital velocity *if* you have enough fuel and daylight left.

Best,

-Slashy

[MabDeno]

OK, here is the Bi-Tri Plane.

12 Wings, 4 engines with 8 fuel tanks and one small reaction wheel (I got sick of the minute balancing dance)

I ran out of fuel just before running out of sunlight.

Without the middle set of wings it couldn't get over 28k altitude.

Javascript is disabled. View full album

[Laie]

But speaking from experience, it's not a linear slog to orbit. The first 10 km takes forever with seemingly no gain other than altitude. Then 25 km happens in the blink of an eye and you're going so quick you have stability issues. 25-30 KM is like a wall, where you are seemingly unable to gain any more speed or altitude. If you get north of 35 km, you're almost assured orbital velocity *if* you have enough fuel and daylight left.

reposting my picture for emphasis:

Red/Green: altitude at mission time

blue/purple: climb rate at mission time

These stalled out early; at about 32km, the climb rate picks up again.

I know little about KSP aerodynamics. But I know that the red/blue vessel had more wings: these were an encumberment early on, and only really became useful at 23-25km. But then tey proved to be so useful as to make up for all the losses they inflicted early on, and remain useful at least up to 35km (meaning that a glider with more wings/lower TWR would climb faster at high altitudes).

The 30km trough had the same depth for all of my vessels, but MOAR WING meant that it wouldn't be as wide.

Ion SSTO should be possible if you take off from a mountain.

[GoSlash27]

The 30km trough had the same depth for all of my vessels, but MOAR WING meant that it wouldn't be as wide.

Laie,

You definitely want enough wing to clear the wall, but any more than that is a liability once you get past it because it's dead weight.

MabDeno,

Cingratulations! You just broke the 1K barrier! I'll get the leaderboard updated in a bit, gotta head out to work.

Best,

-Slashy

[The_Rocketeer]

Looking into this...

Edited November 4, 2014 by The_Rocketeer

[Laie]

Laie,

You definitely want enough wing to clear the wall, but any more than that is a liability once you get past it because it's dead weight.

Sorry, it's been a while. I stand corrected:

(mislabeled it -- it's altitude, not airspeed).

This are ascents with two engines, 12/14 wings, wings not angled, five xenon tanks. Again altitude and climb rate vs. mission time. Climb rate at 29km was a mere 0.5m/s.

Fewer wings were quicker to fall into the hole, but they also recovered better.

It became slightly better when I removed a tank. Flight only lasted 48 minutes instead of sixty, but peaked at a slightly higher altitude due to a faster climb along the way.

Edited November 4, 2014 by Laie

[GoSlash27]

MabDeno,

I got the leaderboard updated. Are you still running .24? Those landing gear pods are worth like a ton and a half with .25 update.

Best,

-Slashy

[GoSlash27]

Aand ol' Slashy is officially on the board. 37,082M at 1,858M/sec. No control surfaces at all and +10% no battery bonus. I think I'm gonna make orbit!

Spirit of Kerbin City .craft

Flight profile:

Launch eastbound at dawn

Pitch up until best speed is achieved, then engage SAS.

At 27 Km altitude, pitch to maintain 5-10 m/sec climb

At 20* pitch, maintain 20* pitch until fuel exhausted.

-Slashy

Edited November 5, 2014 by GoSlash27

[Pds314]

Managed to fly mine into Jool in FAR. It's amazing where 70 kg of Xenon can take you once you are in orbit.

That being said, it wasn't exactly the king of efficiency. It took about 7.4 km/s of Delta-v just to reach orbit. (It got into an unstable orbit with the Apoapsis on the dark side, and fell back down to 36 km before I could send it back into space, flying upside down). Keep in mind that this is in FAR, where normal rockets can reach orbit in under half that.

In total, the thing had about 11.7 km/s of Delta-V, but after reaching orbit, only 4.3 km/s.

The biggest problem for me was figuring out how to avoid racing the sun and winning. I determined that flying until I was at 8000 m altitude and 115 m/s, then banking into a 180 degree turn and going retrograde into orbit was the best solution. The thing is surprisingly nimble at 8000 meters, probably more so than most, if not all, fighters.

I do admit that I used the FAR wing mass/strength scaling to basically neutralize most of their mass though. Granted, they still weigh about the same as stock ones would. (edit: by about the same, I mean like 35% lighter).

Edit: trying to make larger version, 12 ion engines, 13 tonnes, 2 Kerbals, and $300,000. So far, it seems to be extremely finicky. If it goes into a steep dive, pulling up becomes impossible.

On the flip side, it only uses $145000 worth of Xenon, making it more expensive than even conventional rockets.

Edited November 5, 2014 by Pds314

[MabDeno]

Im on .25, does the landing gear weight count now? Doesn't seem to show any change in Ker unless I'm missing something.

[Pds314]

Im on .25, does the landing gear weight count now? Doesn't seem to show any change in Ker unless I'm missing something.

The gear weight doesn't count in .25.2. (else my FAR orbiter would be screwed, having 2 tonnes of gears for 0.85 tonnes of plane) It might count in .25, which would make this exceedingly difficult.

Edited November 5, 2014 by Pds314

[Viragos]

Ok time to post up my work even though I'm nowhere near the milestones

http://imgur.com/a/nZY7l

Not sure what Im messing up on my flight profile, I'm running out of fuel around 25k and cant seem to get enough climb rate to improve that

[The_Rocketeer]

Manned attempt.

Topped the table for altitude, but speed wasn't quite there. I've included screens with max speed ascent and max speed descent.

Javascript is disabled. View full album

[GoSlash27]

The gear weight doesn't count in .25.2. (else my FAR orbiter would be screwed, having 2 tonnes of gears for 0.85 tonnes of plane) It might count in .25, which would make this exceedingly difficult.

That must be what it is. I'm running 25.0.642. All of my old gliders were broken due to the gear. I balance beamed them and they weigh half a ton each!

That's why my latest entry uses no landing gear, just angled wing stubs to serve as skids.

I'm so close to orbit now, I may as well just tough it out.

Best,

-Slashy

Edited November 5, 2014 by GoSlash27

[GoSlash27]

Ok time to post up my work even though I'm nowhere near the milestones

http://imgur.com/a/nZY7l

Not sure what Im messing up on my flight profile, I'm running out of fuel around 25k and cant seem to get enough climb rate to improve that

I think, perversely, that you're running out of fuel because you're carrying too much of it. You may also not have enough wing for the job, but I'm still a newb at using porkjet parts for ion gliders.

If you reduce your xenon tanks from 6 to 3, I bet you'll do better.

In the meantime, do you have a name for this craft?

Best,

-Slashy

Edited November 5, 2014 by GoSlash27

[GoSlash27]

Rocketeer,

I love that the new manned attempts with the command chair are actually competitive with the unmanned drones. Does this craft have a name?

-Slashy

[Viragos]

I think, perversely, that you're running out of fuel because you're carrying too much of it. You may also not have enough wing for the job, but I'm still a newb at using porkjet parts for ion gliders.

If you reduce your xenon tanks from 6 to 3, I bet you'll do better.

In the meantime, do you have a name for this craft?

Best,

-Slashy

No name as yet, and the other issue I think is messing it up is flight path, I tried to roughly follow Yakky's flight plan (North to the pole while climbing then run south along the terminator bearing east to add speed at the end) but every bit of thrust not going to orbital velocity is basically wasted. I'll try cutting fuel and adding wings to see what happens.

Thanks!

[kookoo_gr]

goslash i have a question. I want to build a ship that has docking ports to drop the landing gear in order to reduce weight. is that considered/allowed staging?

[GoSlash27]

goslash i have a question. I want to build a ship that has docking ports to drop the landing gear in order to reduce weight. is that considered/allowed staging?

It would be illegal and also unnecessary. No dropping parts for any reason other than boarding a command chair.

Landing gear are massless and dragless in the latest update, so you'd gain nothing by dropping them anyway. The parts required to drop them would actually add mass and drag to your craft.

Best,

-Slashy

[The_Rocketeer]

Rocketeer,

I love that the new manned attempts with the command chair are actually competitive with the unmanned drones. Does this craft have a name?

-Slashy

I called it the BION II ('Bi-wing'-'Ion' - happened to be the II revision. III revision has 3x the fuel, climbrate stinks but goes like a Duracell bunny).

Also, am I being thick using an OKTO and an EAS-1? Am I right in thinking the chair doesn't make any torque?

Edited November 5, 2014 by The_Rocketeer

[GoSlash27]

All,

My cursory analysis of the new wings was confirmed by last night's flight. The best wings to use now are (in order)

1) Wing Strake M 0.025 Cd 0.2 Cl 0.75

2) Structural D M 0.012 Cd 0.08 Cl 0.25

and

3) the original swept wing M 0.05 Cd 0.6 Cl 1.6

Mathematically modeling their implementation on a previous winning design shows that an installation sufficient to lift the glider over the wall with strakes is just barely heavier than using swept wings (2% heavier), but total drag is slashed by 25% making the strake the clear winner.

The structural D wing lowers drag even more, but it comes with a significant weight penalty.

-Slashy

[GoSlash27]

Rocketeer,

That is correct; the command seat has no control torque and also draws no electrical current.

You might want to consider stepping up from the OKTO-2 to the small reaction wheel. It's only 10 Kg heavier, but puts out 10 times the torque.

Best,

-Slashy

Edited November 5, 2014 by GoSlash27