Helicopters

[Maikie_G]

With the damned aerospace plugin, it\'s possible to build helicopters.

I\'ve built several, and tried several I saw in spacecraft exchange, but they all seem to have on big problem in common.

I can\'t fly them at all.

Could anyone give me a few pointers on this?

[power5000]

ditto/bump

[mockingking]

I built a working one once.

It was pure luck, though. I only just coincidentally hit the centre of mass with the engine :\'(

(Now, helicopters that only go up and down straight, and maybe use RCS to move, are fairly simple. SAS/ASAS and MechJeb can go a long way for those).

[Excalibur]

Before 0.15 hit the the shelves helicopters were actually quite easy to construct. Alas now I\'ve found making a successful one is rather tricky.

I did find that small wings, usually placed very close to the centre of thrust (i.e. adjacent to the rotors) do help with control.

I\'ll try make a stock/damned/mechjeb one for you...

[Excalibur]

Here we go, thirty minutes in the making; I present the Ko-AXE.

Totally stock aside from the Damned Aerospace plugin it can be flown entirely without SAS. To aid in controllability it has a small wing forward, and large canard tail surfaces but no RCS.

Although it is very definitely flyable as you can see, it\'s still a bit of a b*****d to fly and will devour great sods of earth should you allow it.

On take-off only use very low throttle settings, or you\'ll end up like a stuck turtle. You have been warned! Enjoy!

http://youtu.be/tcujF-grU-Q

Craft file attached.

Let me know what you think, plus if you manage to improve it - particularly it\'s vertical landing characteristics.

[power5000]

Really nice i made one that is pretty stable (still in the works) make take a few tips form your design =)

[Excalibur]

Sweet, be my guest. I find the hardest part is getting the rotors directly above the centre of gravity. Takes quite a lot of trial and error to get that right. Another issue is when the wings start producing lift it also screws up the balance; the catch is I\'ve found you do need them for both stability and control.

The current basic lift model used by KSP makes it very hard to do any vertical landings because they still generate a daft amount of lift at slow speeds. This makes it difficult for you to hover with no horizontal velocity. When the lift model is updated to introduce stall parameters things should be a lot more fun interesting.

[power5000]

yeah i noticed that with my VTOL prototype

[colmo]

Taking a few tips from Excaliber, I managed to build a working chopper.

http://kerbalspaceprogram.com/forum/index.php?topic=13711

It\'s much bigger than his, using lateral tanks, but those come in handy for tuning the centre of mass, which is easier to move than the centre of thrust (the rotor).

When I tried the Ko-AXE, I found it tended to heel backwards and crash - I didn\'t see the throttle warning though!

My own design heels forward slightly, but well within trimmable limits, and requires no SAS, as that makes it a pig to turn.

As there is no tail rotor, we\'re forced to use control surfaces to make yaw manoeuvres, and as we\'re moving slowly, we need a lot of them!

Placing floodlights on the underside really helped in landing - it gives a much better perception of how far away the ground is.

A few things I learned were:

1) Keep your mass central - I had a MkI that had lateral tanks on trusses, which liked to go into a flat spin. Removing the trusses improved that handling a lot.

2) Keep the mass low. Most of the upright control surfaces are below the centreline of the craft. This may require using hardpoints to lower landing gear, which will lower CoG even more.

3)If the chopper likes to pitch fore or aft, place wings at nose and tail. If it\'s reluctant to pitch, move those surfaces into the centre.

4) Use plenty of upright control surfaces to prevent spinning.

5) Use a joystick to fly it! You really do need fine throttle control (as the pitch of a chopper directly impacts lift) and you can\'t do that while controlling the orientation of the craft at the same time without major remapping of keys.

[Twinky827]

I made this bigger helicopter.

[Alias]

I managed to create a stable easy to fly chopper. I attach lasers to it and use it to clean up debris. I included the craft file

[colmo]

I managed to create a stable easy to fly chopper. I attach lasers to it and use it to clean up debris. I included the craft file

It sure ain\'t pretty, but that thing flies a treat. My only (very slight) dislike is that it doesn\'t turn when you bank, it just leans.

I also note that ASAS is far more effective than the avionics unit, which led to me checking their configuration files and discovering they are setup entirely differently. I\'ll get to it configuring a chopper-specific ASAS. Any thoughts on what part to use? I was thinking a Mk1 to Mk2 adapter piece, as I\'m fond of the Mk2 look. Same weight and specs (aside from handling mods) as an ASAS otherwise.

[Alias]

I tried really hard to get the banking down but I found it impossible. This is the best I could do and if you roll and pull up pitch it does as close the the same thing as I could accomplish. But like you said it flies really well and I consider that a win

[colmo]

I tried really hard to get the banking down but I found it impossible. This is the best I could do and if you roll and pull up pitch it does as close the the same thing as I could accomplish. But like you said it flies really well and I consider that a win

Give my choppers ago - I released three this morning/last night (depending on how you define those terms )

To get a chopper to turn when you bank, you need the centre of lift and/or side-profile drag to be behind the centre of rotor thrust. It doesn\'t have to be far, and it might only work if your attitude is slightly nose-down (thus tilting the rotor forwards to get the angle). All my choppers behave this way, and thanks to the X-wing style winglet formation you used, they handle better than they did.

When placing the rotor (or tweaking the front-rear weight bias), I prefer a chopper than will lean a hair forward rather than a hair backwards. It\'s almost impossible to nail it absolutely neutral, but it\'s easier to control and land a chopper that wants to go forwards.

I haven\'t started work on a helicopter ASAS unit yet. The current one is more like an autopilot, but you have to turn it off to make meaningful manoeuvres.

[Alias]

Your helicopters fly great GJ. I\'m going to be working on a new chopper taking some tips from yours.

[Alias]

Colmo, after studying your designs I have created a new chopper. Check it out tell me what you think. Just go easy on take off the nose likes to drag. But once in the air it flies perfect

[colmo]

My latest creation - a dual-rotor!