Nasa AD-1 (pivoting wing jet)

[wossname]

Stumbled on this earlier today: http://en.wikipedia.org/wiki/NASA_AD-1

This aircraft is a variation on the swing-wing concept - the difference being that one wing sweeps forward and the other wing sweeps back by the same amount.

In other words the wings are on a turn-table on the roof!!!

RULES OF CHALLENGE:

1 - no cheats.

2 - FAR is ok as long as you declare you are using it, we'll have 2 leaderboards, one with one without FAR as is customary by now .

3 - Kerbal Attachment System and/or Infernal Robotics mods are allowed (probably necessary?!).

Basic challenge:

1 - Your MANNED (Kerballed) aircraft will take off from KSC runway with wings in normal configuration (both wings at 90 degrees to fuselage).

2 - Attain a stable altitude of 5000m and then swing your wing (clockwise or anticlockwise, whichever you like) by at least 45 degrees. 60 is preferable. This will be "eyeballed" from a well-positioned screenshot!

3 - Hold steady level flight for 2 in-game minutes without altitude changing by +/- 500metres.

4 - Return to normal flight wing-sweep and return to KSC runway for a safe landing. No damage is permitted to the aircraft.

5 - The plane needs to have at least a passing resemblance to the NASA AD-1 experimental aircraft. Scale is not important.

Bonus points for:

BEHEMOTH - heaviest plane to complete the challenge gets 100 pts bonus. (marked in leaderboards with "MASS").

SONIC BOOMERANG - reach 1000m/s at any altitude while wings are pivoted at least 45 degrees from normal. 100 pts. (marked in leaderboards with "BOOM").

PARTS BIN SPECIAL - plane with fewest parts to complete the challenge gets 100 pts. (marked in leaderboards with "RUSTBUCKET").

LOW AND SLOW - plane with lowest horizontal (surface) speed at touchdown at KSC runway after mission. 100 pts. (marked in leaderboards with "CHILLIN").

Leaderboards:

Non-FAR Mode

1 -

2 -

3 -

FAR Mode

1 - hoioh - 300 points - At the moment Behemoth, Parts Bin Special, Low and Slow

2 -

3 -

Notes:

This is my first challenge, I hope it is amusing to someone. I had fun with this one. My first attempt was actually surprisingly stable, perhaps BECAUSE of KSP's aero limitations rather than in spite of them. This should be regarded as an "easy" challenge, at least for the basic requirements. I hope it has some scope for larger constructions.

Those aiming for the "BEHEMOTH" challenge can waive the "passing resemblance" constraint if they declare "BEHEMOTH" in their posting. e.g., if you want to have 8 sets of pivoting tri-plane wings - then you win the internet for a day.

Edited April 6, 2015 by wossname

[Feradose]

Is infernal robotics allowed?

[wossname]

Yeah, actually I think that's what I meant when I wrote the above post. Do'h, I'll edit it now, thanks.

[Astrofox]

Already did that in 0.25, here's a pic.

I might use that old craft; i just have to pull it into my ships files.

[hoioh]

I just rebuilt the plane using a lot of B9 parts simply because it looks better than stock. (There's no strict stock requirement in the rules as far as I can see.)

In the stock souposphere it flies like a brick the moment you start sweeping those wings, it tumbles towards the side where the wing is swept backward. So I filmed what happens to the center of lift inside the SPH where you can clearly see the center of lift remains in the middle of the plane, except according to KSP it moves backward. This is really what we want in order to gain balance at higher speeds, except I couldn't manage a speed above 160m/s with the current design. Oh and I botched the landing, so this isn't really a worthy entry, just wanted to share my experience, maybe someone else has a good idea on how to fix these problems without adding a whole pile of SAS modules to the craft (which would be wasteful).

First I'm going to try it in FAR and see if it responds any better that way and if that doesn't work a rebuild will be required.

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[DancesWithSquirrels]

Hoioh - Looking at your airplane, I would suggest making your wings fore-aft symmetric. In the current configuration the center of lift for the front wingtip will move forward less than the rear wingtip COL moves back, which would produce the lift shift you mention. And the COL for the front swept wing will be further from the fuselage, which would cause a roll towards the rear wing.

[wossname]

I just rebuilt the plane using a lot of B9 parts simply because it looks better than stock. (There's no strict stock requirement in the rules as far as I can see.)

Yeah that's totally fine. The rules are deliberately pretty relaxed, I just want people to have fun really.

[hoioh]

Hoioh - Looking at your airplane, I would suggest making your wings fore-aft symmetric. In the current configuration the center of lift for the front wingtip will move forward less than the rear wingtip COL moves back, which would produce the lift shift you mention. And the COL for the front swept wing will be further from the fuselage, which would cause a roll towards the rear wing.

I'll try that this weekend, let's see if that fixes my problem, it sounds logical enough.

[hoioh]

It works, but in Stock atmosphere it still won't behave because it thinks the center of lift moves backwards a lot when I twist the wing. It behaves better in FAR, but I'm still struggling with making it fly proper before I post a movie here.

[hoioh]

Well, let's just say it works better in FAR, but not exactly like the real thing, unfortunately.

In the VAB I noticed the Center of lift moves in an even stranger way than with stock earo, it takes on a sort of water-drop shape path, starting with the spherical end, then outwards sideways only to return a little ways on and then stay in the center of the fuselage a little ways backward from where it started. Not nice, but manageable.

It only handles in any way pleasant at high speeds, low speeds just suck no matter what you do with the wing.

Vidoe upload takes a while, I set it to publish as soon as it's done.

And here's the craft if you're interested in trying, required Infernal robotics, B9, and FAR mods to work.

Craft file

Edited April 5, 2015 by hoioh

[wossname]

I'm happy to add this to the scoreboards if you can provide me with the stats. My broadband speed isn't good enough to read your airspeed from the video.

[hoioh]

Stats, well, mods used: IR, FAR & B9

Top speed before freaking out completely: 541.6m/s

Width: 32

Length: 32.3

Height: 8.1

Parts: 62

Weight: 23.1t (Includes 990 units of fuel)

Dry mass: 18.2t