Propeller Speed Record

[ralanboyle]

If someone has already created this, please post a link. I looked. 

Just a straight speed challenge: How fast can a prop driven electric craft move?

Rules: 

Craft must be ELECTRICALLY powered.  - This is for standardization. 

What goes up must come down, in one piece. No dropping parts. 

Your craft must land in one piece. I understand you might be a long way out over water or very high after completing your speed run, so it is acceptable to just fly around KSC and land to show that it can land without falling part.

This is not a test to failure, if your craft falls apart trying to achieve high speed, then it doesn't count. The idea is to be repeatable. 

Your speed must be recorded in LEVEL flight. So, your screen shot needs to show your speed and your attitude. 

No additional propulsion is allowed. Just electric motors. No glitch drives or exploits, including the heatshield lift exploit. 

No extreme clipping/offset. Parts need to visibly attach. This is intended to cover a range of aero exploits... don't go looking for exploits, that's not the point. 

No physics/parts mods. DLC required.

 

Edited January 29, 2021 by ralanboyle

[fourfa]

Might need rules to exclude this type of contraption...   will be watching with interest though, I’d very much like faster and more usable prop-driven craft for career. The biggest problem for me is not raw speed but weird physics glitches when using physical time-warp

[ralanboyle]

31 minutes ago, fourfa said:

Might need rules to exclude this type of contraption

Updated to specifically outlaw this silliness. Like you, I want to see some practical aircraft. I generally find no reason to use propeller craft, which is too bad since I love them IRL. 

[camacju]

I think Bradley Whistance got a prop plane to 1200m/s using reaction wheels and wings. Not sure how much better it's possible to get without using heatshield lift

[ralanboyle]

14 hours ago, camacju said:

I think Bradley Whistance got a prop plane to 1200m/s using reaction wheels and wings.

Are you talking about motors and propellers, or some kind of glitch powered device? Got a link? 

I've never seen an airplane built with the Breaking Ground parts go faster than 230m/s.  I'm hoping some of you can do better than that because I feel like it should be possible. 

Also, is my signature displaying correctly?

Edited December 7, 2020 by ralanboyle

[fourfa]

All the speed record planes I’ve seen (claiming this or that on youtube) use props that are offset way out into open air, not visibly connected to the craft.  Typically needing some tall launch tower for ground clearance, or VTOL routines diverging pretty far from reality.

I’ve got a 300+m/s ducted fan craft I can throw up later, since we seem to just need a stake in the ground to get this rolling

[ralanboyle]

7 minutes ago, fourfa said:

All the speed record planes I’ve seen (claiming this or that on youtube) use props that are offset way out into open air, not visibly connected to the craft.  Typically needing some tall launch tower for ground clearance, or VTOL routines diverging pretty far from reality.

I’ve got a 300+m/s ducted fan craft I can throw up later, since we seem to just need a stake in the ground to get this rolling

edited regarding clipping. 

[fourfa]

Alright just for a point of reference:

https://kerbalx.com/fourfa/Ducty

314m/s.  This was an experiment on a stowable ducted fan / turbine as launch stage for a nuke-only SSTO; still working on shielding the fan blades from drag when the service bay closes.  Perhaps a bit clippy for the IRL-alike spirit of the rules so far; but this accidentally became my fastest prop

Generally I have the sense that the motors and prop parts were not extensively tested for balance before release (and the early update patches).  The motors are WAYYYY to powerful for realistic-looking planes, they just make more and more power as you slap on more and more blades. For 2-3-4 blades you only need like 2% on the motor size slider, and  you'll struggle to make 100m/s.   Speed record planes are likely to have lots of fuel cell power, lots of blades, but only a couple full-power motors

Edited December 8, 2020 by fourfa

[fourfa]

For instance this is all motor, 4 fuel cell arrays running full blast.  The medium size ducted fan blades seem to be goldilocks between RPM and thrust per blade.  So... 323m/s

Edited December 8, 2020 by fourfa

[doggonemess]

16 hours ago, ralanboyle said:

Also, is my signature displaying correctly?

In case nobody else let you know, your signature is not showing. Just the 2G planet at the end and four 'minus' images before that.

[fourfa]

The obvious next step (double the power) gets 334.6m/s.  Interestingly the max seems to be Mach 0.955 independent of altitude - as altitude increases, density decreases, speed decreases a little, but Mach number stays exactly 0.955

Scraping sea level (<100m) same craft gets 336.2m/s

Edited December 11, 2020 by fourfa

[fourfa]

OK this got fun.  I noticed that even with 3 rows of 8 props per motor on the craft above they're all still at max RPM.  Also that the leading-edge motors have a lot more drag than the trailing edge motors.  I built a new airframe for minimum drag and maximum props per motor, and looking more like an experimental speed platform.  I didn't get the motor to slow down until 8 rows of 8 props each.

https://kerbalx.com/fourfa/Speed-Demon

351.1m/s ...  and Mach 1.016!!!

Edited December 11, 2020 by fourfa

[ralanboyle]

3 minutes ago, fourfa said:

8 rows of 8 props each

How are you attaching all of these? I assumed that they would not actuate if not attached to the attachment nodes. 

[fourfa]

All surface attached; I've never seen any problems doing that.  A little offset nudging to pack them all in but all still on the spindle.  Looks kinda evil like real turbine blades - but feel free to make a challenge rule if it's questionable

[ralanboyle]

2 minutes ago, fourfa said:

All surface attached; I've never seen any problems doing that.  A little offset nudging to pack them all in but all still on the spindle.  Looks kinda evil like real turbine blades - but feel free to make a challenge rule if it's questionable

No rules, this is the sort of thing I was hoping for. I never considered surface attaching them. Are you still able to adjust pitch in flight be assigning a command group? 

[fourfa]

Blade pitch assigned to H/N (translate forward/back), motor torque on Main Throttle.  There's so much power, it's like 8G of acceleration when taking off!  It's really a thrill to fly

[ralanboyle]

I may stack about a bajillion of these in a row to make a KSP "electric Turbofan." (Yes, I know that's not really a thing.) I've got a couple other challenges I'm working on at the same time, so i may not do it tonight. 

[fourfa]

I suspect mounting the blades on the larger-spindle large motor variant may achieve more lift and higher speed.  Just needs a different tail section for clearance if we're avoiding visible clipping

[ralanboyle]

1 hour ago, fourfa said:

if we're avoiding visible clipping

Reasonable clipping if fine. 

[Arco123]

One sec. Let me get my ship engine. 

[king of nowhere]

On 12/7/2020 at 12:50 AM, ralanboyle said:

 I want to see some practical aircraft. I generally find no reason to use propeller craft, which is too bad since I love them IRL. 

The plane i show here has a top speed of 235 m/s (the highest i have in a screenshot is 220, which is a bit safer). It won't make a speed record here, but it was enough to go all the way around Laythe to collect science from every single biome in a few hours (and it is stable enough that i can point it in the right direction and leave the game running in the background, checking only every few minutes). It has infinite range with rtg electricity, it lands and take off from water, and it goes back to orbit too. It also works on Kerbin. It flies on Eve, but it can't survive reentry and it can't return to orbit.

I'm not competing for speed, but if you want a practical aircraft, this may be the vessel for you

[fourfa]

355.6m/s, Mach 1.033

larger spindle motor was a bust. Working on drag and mass reduction got a few more m/s here

Edited December 12, 2020 by fourfa

[ralanboyle]

@fourfa, you mind putting this craft on Kerbalx? Id like to see some of the fine points of how you've got the props angled etc. Clearly you've got it figured out. 

[Dman Revolution]

4 hours ago, fourfa said:

355.6m/s, Mach 1.033

I got you beat by about 8m/s. 12 blades per rotor, 4 rotors, each clipped inside a fairing. This was also with the torque overclocked significantly.

[fourfa]

Alright!  FYI in the future you should make sure  to zero out that vertical speed - even just that little negative 5.7 m/s dive would have given me a few extra m/s.  But I have no doubt that craft would have mine beat in level flight regardless.

Did you find maximum power just scraping the water?  Some of mine did, though the last two I showed seemed to gain speed up to about 1500m and I always found my best pass with them in a very slow climb, so it would rise slowly through its ideal altitude band

And we’ll need a ruling on using KAL1000s to boost power over stock for this challenge

Edited December 12, 2020 by fourfa