Turboshaft Helicopters

[Azimech]

Because racing improves the breed.

The idea is to improve my concept of the turboshaft and the principle of the KSP helicopter in general.

Want ideas? Take a look at my signature, download some helicopters, take them apart and learn how they work.

This challenge is aimed at stock aerodynamics. Building and Flying a helicopter using FAR is even harder. There will be a challenge for that in the future. Even after KSP 1.0 is released, old aerodynamics will apply for this one and a new challenge will be started.

Stock parts only. Whatever mod you use in the editor is your own business, except Tweakscale and Tweakable Everything.

Mods recommended are Part Angle Display, Kerbal Engineer, Editor Extensions. Eventually there will be a different challenge aimed at mod use.

I'm not interested in part count, size, mass or looks. Whatever it takes to get the job done. But, more parts means more drag.

The idea is that I test every craft and award points for the following:

Fuel Consumption(FC) at 500 meters: less is better. The max value will be multiplied by 100, then divided by 2 and subtracted from the number of points (example: 0.77 becomes -39 points).

Endurance (E): max flying time at max throttle, until tanks dry. Number of seconds divided by 10. If max throttle affects reliability or controlability, reduce thrust settings on the turboshaft.

Maximum Altitude (MA): amount of meters divided by 100. If the tanks run dry while it's still climbing, the altitude will be used the moment engines shut down.

Maximum Climb Speed (MC) at 2000 meters: meters per second multiplied by 2.

Maximum Horizontal speed (MH): SAS loss of control will occur above a certain speed. Meters per second multiplied by 3. Mechjeb will do the flying.

Reliability ®: -50 points for a jam, rotor strike or RUD during normal flight with a max horizontal speed of 5 m/s.

Survivability (S): 10 points for a soft landing with engines off. Testing starts at a ASL 500m at KSC. It's a measure of internal friction, auto-rotation saves lives.

Take off Throttle (ToT): measures the power to weight ratio of the craft. 100% minus throttle setting = number of points.

Lifting Power (LP): Measured with full tanks, 1 point for every 1000kg extra ballast, lift off at full power and a max climbing speed of 0.5m/s. It's a measure of strength of the construction and internal friction. No points will be subtracted if the craft fails. There must be a mounting point directly under the shaft. Even with multi-rotor designs, I want to test the engines/rotors, not the construction mating them.

Directional Precision (DP): amount of degrees deviation from selected vector, with zero roll (i.e. flying like a crab) at 5m/s horizontal speed and almost no vertical speed: subtracted from points.

SAS Stability (SS): does it get confused or does it want to fly in the same direction for 5 minutes. It's a measure of balance, more mass off center means it will accelerate, above a certain speed create extra lift on one side beyond max control input and start to roll or pitch. It's also a measure of tolerances: the more the shaft wobbles, the earlier the SAS recalculates it's control values and starts to deviate. 25 points using Mechjeb, 50 using stock SAS, for a max total of 75.

A way of braking to slow down/stop the rotation of the rotor(s): 5 points. My CTR2 can take up to 20 minutes to land from 5km without the brakes. I'm tired of waiting.

Twin engine: 10 points.

Coaxial: 100 points!

Most points will be awarded for a working cyclic/collective: 1000!

Required: an advanced probe core pointing up and a probe core pointing in the regular flight direction.

I don't calculate points for crashing or ease of landing, since pilot error is something different than flight performance. Helicopter flying is very difficult in real life and so is it in KSP.

Since testing this way takes a lot of time, don't expect quick results. If you want quicker results, post some screenshots of things like max. fuel consumption and ease of control.

Tip: twins and coaxial rotors are much more stable than single rotor designs!

Check regularly because rules may change!

Good luck & have fun!

---

Example: my CTR2 RC2:

Fuel Consumption: 0.68 -> -34 points

Max Altitude: 8083m -> 81 points

Max Climb Speed at 2000 meters: 14m/s. -> 28 points

Max Horizontal Speed: still testing

Survivability: 10 points, it sinks and touches down like a feather.

Reliability: no events

Endurance: 770 seconds - 77 points

Take off power: 20% throttle -> 80 points

Directional precision: still testing

Lifting Power: still testing, currently at 41 tons.

SAS stability: still testing

Coaxial: 100 points

Braking system: none

Preliminary results (check again in a few days)

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RS Gyro III

Fuel Consumption: 0.69 -> -34 points

Max Altitude: 6571m. -> 66 points

Max Climb Speed at 2000 meters: 8.6m/s. -> 17.2 points

Max Horizontal Speed: still testing

Survivability: still testing

Reliability: no events yet

Endurance: 2167 seconds -> 216 points

Take off power: 48% throttle -> 42 points

Directional precision: still testing

Lifting Power: still testing.

SAS stability: still testing

Coaxial: nope

Braking system: not tested yet

---

Spreadwing Vc

Fuel Consumption: 0.77 -> -39 points

Max Altitude:

Max Climb Speed at 2000 meters: 20.2m/s -> 40.4 points

Max Horizontal Speed: still testing

Survivability: still testing

Reliability: Engine two exploded at 4:30, 4800m. altitude. -50 points

Endurance: still testing

Take off power: 23% throttle -> 77 points

Directional precision: still testing

Lifting Power: still testing.

SAS stability: still testing

Coaxial: nope

Braking system: not tested yet

---

Edited February 17, 2015 by Azimech

[Tsevion]

Man, it may be time to update my Electric Helicopter... I was planning on revising it when 1.0 came out to see if was still possible in the new aerodynamics. I may need to start early.

But I think I'd win your scoring: Fuel Consumption: 0, Endurance: Forever = All the points.

Side note on your challenge, you may want to actually define what constitutes a helicopter (most notably VTOL, no engines angled down at all, rotation of some sort, and possibly a non-rotating body?). Depending on your definition some of my WhirlyGigs from early helicopter design might qualify. Or if specifically needs to be based on your design of turbo-shaft you should call that out.

[Azimech]

Yes, the focus is entirely on turboshafts. The reasons are simple: they're harder to build, harder to tune and overall more of a challenge since there are so many parameters. Plus we meet them everyday in real life. The real world electric helicopter prototypes have got nothing to do with what's possible in KSP. The Sikorsky Firefly can stay in the air for a max of 18 minutes. Even electric planes perform better.

It should be based on a turboshaft concept - turbine blades on an axle blown to rotate, thereby no thrust along the axle axis is allowed, since that is a form of cheating. All thrust should come from the rotation of the rotor blades. The rest is open. Want to build a reduction gearbox? I don't know how but fine. Use rocket engines to drive the turbine? Good luck, might score a lot of points in a few fields but not in others.

[Right]

Very cool designs. Much tuning I'm sure.

Gears are possible, just horribly inefficient.

[Redshift OTF]

Well I have my first submission for this thread. Trying to create a stock bearing that has a low part count, high durability and good performance is hard and this is the best I have so far. The overall design isn't pretty but I wanted a helicopter that was somewhat controllable.

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It is recommended you use MechJeb's UP ability in the Smart Ass surface section and I had to resort to using Vernor engines to make this machine steerable somewhat. You also need to roll left a lot to keep it going forward but it is pilot-able which is what I was looking for. Also the swept wings on the end of the rotors help with stability and remove unwanted stored directional energy in the rotors.

Download here.

Parts = 166

Mass = 32.5 tons

- - - Updated - - -

Oops, I forgot to place a forward facing cockpit on the design. You can attach one to the end of one of the SAS booms if you need it to validate the entry.

[Azimech]

I'll try to test it today, no promises though. I've got my girlfriend for the weekend.

[Tsevion]

they're harder to build, harder to tune and overall more of a challenge since there are so many parameters.

Can't say I agree with this... maybe true vs. something like an SAS powered spinner, but a proper wheel-powered electric helicopter is much harder. Jet engines are an easy source of power compared to wheels, much less finicky and much more powerful. But I can respect wanting to investigate turboshafts more... they're pretty fun to build and fly. So here's one I built for you. It's maneuverable, relatively easy to fly, can go 4 m/s vertical and 24 m/s horizontal, and can get up to 4km given its current fuel supply, then fall back down safely unpowered. It's also pretty easy to land on the VAB roof... all while still having enough power to spare to lift a full orange tank (36t).

The Spreadwing IIIc - powered by 2 Tsevion Enterprises Hexa-turbine IIIc.

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[Tsevion]

Well, after looking at your stats, I decided that wasn't good enough... so I built a new engine. Now I get some pretty extreme performance.

The Spreadwing V-c

Using 2 Tsevion Enterprises Quadrobine IIc Engines.

Climb Speed: 20 m/s

Horizontal Speed: 40 m/s

Max Altitude: 7 km

Max Lift capacity: 120t (yes, it can lift twice its own weight)

Weighs in at 308 parts and 60.2t

She's a bit of a beast.

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[Guest]

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[Jakalth]

My entry, and, my first WORKING Rotorcraft, the twin rotor, jet turbine Helli, The Jak-16 Albatross. <---download link

It's a bit of a heavy weight and not exactly the easiest to fly... But it is durable and can handle as much stress as you dare to throw at it. At least as much as I dared throw at it... Specs are as follows:

Part count: 597

Weight: 56.7 tons

Cost: 333,634

Max Altitude: 2,950m @ 100% power

Climb speed: about 6 m/s @ 67% power, about 8 m/s @ 100%

Max level forward speed: 55 m/s @ 1300m and 75% power

Control ability: fair

But, my true contribution to this contest is not the helicopter, but the rotor design used on it. The SAS controlled, reactive pitch blades. Basicly just blades that use sas control to dramatically increase lift AND rotor efficiency. Use these on your rotorcraft designs and you'll likely see at least a 50% increase in lift over the blades your already using while also reducing the amount of power needed to turn them.

At least it looks like a helicopter.

The rotors themselves are a hybrid-reactive rotor design that are quite small in size but are capable of generating a LOT of lift. By setting the rotation in the rotors sas module, to the opposite direction of rotation, it deflects the rotortip upwards, increasing lift dramatically, without increasing the amount of torque needed to turn them. This is a HUGE improvement over conventional lift rotors.

The rotors themselves can be powered fully electrically, using enough adv SAS modules(at least 3), to generate lift for a smaller rotorcraft.

To operate the Albatross:

1: Tap space bar to free the rotors, so they can spin.

2: Use [ or ] to cycle to both rotorblades and set their rotation too 100% counter rotate(left rotor should be Alt + E, right rotor should be Alt + Q, and hold until they are at full spin)

3: Switch back to the main body of the albatross and turn on SAS

4: Set your engine power to between one and two notches above 0%, so about 5-10% and then activate them

5: Let the rotors stabilize, they should come to a complete stop as the SAS and engines counter each other, before starting to turn the correct way.

6: Once the rotors are stable, and the engines are up to this idle speed, turn the power up to just past the first large notch, or about 1/2 power.

7: Have a good flight, and feel free to turn the power up as high as you want once the craft is airborne and stable.

[Tsevion]

But, my true contribution to this contest is not the helicopter, but the rotor design used on it. The SAS controlled, reactive pitch blades. Basicly just blades that use sas control to dramatically increase lift AND rotor efficiency. Use these on your rotorcraft designs and you'll likely see at least a 50% increase in lift over the blades your already using while also reducing the amount of power needed to turn them.

The problem is that this is because control surfaces are just broken, not because they're "smart". It's essentially infiniglide. I made a video describing the issue a ways backs. Now if you're trying to build the most effective rotor in the current aerodynamics system, warts and all, then you are correct... really the entire rotor should be made of control surfaces, you probably won't need an engine for it at all. But since this competition is trying to invent rotors powered by turbo-shafts, having a large portion of the power coming from the rotor blades seems out of contest scope.

[Jakalth]

That may be true Tsevion, but the rotors themselves want to spin backwards due to the control surfaces, even without the SAS module. Thus producing basically no lift on their own. Still you do have a point. I've just had no luck using conventional rigid rotors.

[Guest]

Designing a high rpm mini-rotor with turboshaft

[Azimech]

That's very cool!

I've tested a bit, not yet finished but i have a few results.

[Guest]

That's very cool!

Thanks!

New version, more compact and light still very high speed! (made with editor extension)

Edited February 17, 2015 by RevanCorana

[Majorjim!]

Thanks!

New version, more compact and light still very high speed! (made with editor extension)

http://i.imgur.com/T6bvpUm.jpg

http://youtu.be/2pkmRBJl6aA

http://i.imgur.com/jQbpk6V.jpg

Those wheels break @ 20m/s. Have you tried it with some weight on the shaft?

[burnoutforzai]

Whoa, those wheels look bloody reliable!

I might use them on some of my craft.

Edit: majorjim's right, didn't think about that.

[Guest]

The whole engine part is hidden inside the rotor

The rover wheels grants suspension so that the rotor blades can work with a bit of reactivity in awkward angles.

There's a docking port for warping speed

I didn't really test yet with weight on the blade though, but I'm trusting it may work with good struting and octogonal strut as structural base of the blade

Current state craft (preview):

https://www./?s0g5wolneeg5fjr

[Redshift OTF]

Thanks!

New version, more compact and light still very high speed! (made with editor extension)

http://youtu.be/2pkmRBJl6aA

This I am very impressed with! I'm surprised those rover wheels are up to the job. Don't feel bad that it jammed at the end, most of my designs jam without a load on the shaft. The centrifugal force of Props and rotors keeps the whole engine more stable. Have you got a download of that?

Edited February 17, 2015 by Redshift OTF

[Jakalth]

@ RevanCorana: You could try adding just 4 more wheels to your turbine design. One of the primary reasons they fail like that is the part your using to hold angular forces, the stayputnic, is able to slip between the wheels while under high stress load/speed. having a single set of 4 wheels, offset 45 degrees from those you already have on the top stayputnic, might be enough to counter this. these wheels would not even need to touch the stayputnic most of the time, only when it starts to wander off center. Worth testing at least.

btw: very nice little design there. I keep going overkill on durability myself, which is why my bearings tend to use landing gear and are a bit bulky and high on part count...

[Redshift OTF]

I'm trying those probe cores on my new engine and they are much more slippery than the white cone adaptors I was using. Unfortunately my engine spins so fast now it rips itself apart. More testing!

[Azimech]

Thank you for your effort, it's much appreciated! However, this is the helicopter challenge. If requested I could start a turboprop airplane challenge as well :-)

But I'll test your aircraft and look at your improvements. Which of my engines did you take to enhance, by the way?

Oh and about KSP crashing: I always power down the jets before switching scenes. I do it the quick & dirty way, with hyperedit: slam the fuel slider to zero.

[Lothsahn]

Sorry about that. I deleted the post. I meant to put it in your stock craft turboprops.

It's here:

http://forum.kerbalspaceprogram.com/threads/109511-STOCK-HELICOPTERS-TURBOPROPS-New-Yelling-Gazelle!?p=1742358&viewfull=1#post1742358

It uses the engine from the 77I-7A2O "Screaming Turtle".

[Lucky Luke]

This so incredible ! Congratulations, testing it right now

Could you explain how you came up with this design ? I would be fascinated to hear about how it works !

[Azimech]

Hi! Welcome to the forum!

It's a long story, I suggest you start with taking a look at my blog :-)