Electric orehauler racing

[Pds314]

Mission

The objective in this challenge is to race to the island runway and back using only electric charge stored in a battery for propulsion. The catch is that you must carry one unit of ore for every unit of electric charge you start with.

 

Rules

You don't need to come to a complete stop on the island runway, but you do need to turn around before taking off to go back to the KSC.

Your time starts when you begin moving and ends when you come to a complete stop (<1.0 m/s) on the KSC runway.

You may not break or decouple any nonempty ore tanks. Discarding absolutely anything else during the run is acceptable.

No jets/rockets/LF/glitch drives. Parachutes besides kerbal EVA parachutes are not permitted. No generating electrical charge.

No mod parts or physics alterations. DLC is allowed and very useful.

Leaderboard 1: best runs

1. mystifeid: 5:34 in the Fat Boy (1950 EC octa-engine push-pull conventional monoplane)
2. ralanboyle: 6:24 in the Electric Cargo 4 (3450 EC octa-engine push-pull blended delta monoplane)
3. Pds314: 7:30 in the Orecceleration (900 EC twin-engine pusher short-winged monoplane)
4. vyznev: 9:15 in the Electric Ore Hauler Mk2 (300 EC hex-engine tractor conventional monoplane)

Leaderboard 2: all runs

1. mystifeid: 5:34 in the Fat Boy (1950 EC octa-engine push-pull conventional monoplane)

2. mystifeid: 5:56 in the Fat Boy (1950 EC octa-engine push-pull conventional monoplane)
3. ralanboyle: 6:24 in the Electric Cargo 4 (3450 EC octa-engine push-pull blended delta monoplane)
4. mystifeid: 7:04 in the Nuthin Special (600 EC quad-engine push-pull conventional monoplane)
5. Pds314: 7:30 in the Orecceleration (900 EC twin-engine pusher short-winged monoplane)
6. ralanboyle: 7:34 in the Electric Cargo 3 (1200 EC twin-engine push-pull blended delta monoplane)
7. vyznev: 9:15 in the Electric Ore Hauler Mk2 (300 EC hex-engine tractor conventional monoplane)
8. vyznev: 10:06 in the Electric Ore Hauler (300 EC quad-engine tractor conventional monoplane)

Edited March 12, 2020 by Pds314

[vyznev]

Do I have to be on the ground while turning around? Because on my best run so far, I kinda wasn't.

(Came down a bit too fast, did a touch-and-go bouncing off the island runway, turned around in the air and managed to land on the second attempt. I did come to a stop before taking off again, but forgot to turn around a second time.)

Anyway, nice challenge. I was playing around with Breaking Ground electric props anyway (for an Eve ascent vehicle), so this was a perfect fit. I'm still trying to figure out exactly how to make the best use of all these DLC parts, so this plane probably won't be breaking any speed records. But at least I can set a baseline for others to beat.  

This thing is basically a small ore tank with wings and a tail. 300 units of ore, 300 units of electric charge. It flies just like any normal plane, and is stable enough that SAS is strictly optional. (I flew this mission without it, if only to conserve power.) Stage to start the engines, throttle controls torque. The main quirks are that there's no movable rudder, so steering off the ground is by roll and pitch only (which is how I tend to usually fly anyway), and that the H/N keys ("translate forward/back") adjust propeller pitch. For optimal thrust, you'll typically want to try to keep the prop AOA between 5° and 10°.

Spoiler

Final elapsed time: 10:06. I could've almost certainly got it under 10 minutes if I hadn't messed up the first landing.

More pictures: https://imgur.com/a/iY8LgRq

Craft file: https://pastebin.com/3erfS5GS

 

Edited March 4, 2020 by vyznev

[Pds314]

2 hours ago, vyznev said:

Do I have to be on the ground while turning around? Because on my best run so far, I kinda wasn't.

(Came down a bit too fast, did a touch-and-go bouncing off the island runway, turned around in the air and managed to land on the second attempt. I did come to a stop before taking off again, but forgot to turn around a second time.)

Anyway, nice challenge. I was playing around with Breaking Ground electric props anyway (for an Eve ascent vehicle), so this was a perfect fit. I'm still trying to figure out exactly how to make the best use of all these DLC parts, so this plane probably won't be breaking any speed records. But at least I can set a baseline for others to beat.  

This thing is basically a small ore tank with wings and a tail. 300 units of ore, 300 units of electric charge. It flies just like any normal plane, and is stable enough that SAS is strictly optional. (I flew this mission without it, if only to conserve power.) Stage to start the engines, throttle controls torque. The main quirks are that there's no movable rudder, so steering off the ground is by roll and pitch only (which is how I tend to usually fly anyway), and that the H/N keys ("translate forward/back") adjust propeller pitch. For optimal thrust, you'll typically want to try to keep the prop AOA between 5° and 10°.

  Reveal hidden contents

Final elapsed time: 10:06. I could've almost certainly got it under 10 minutes if I hadn't messed up the first landing.

More pictures: https://imgur.com/a/iY8LgRq

Craft file: https://pastebin.com/3erfS5GS

 

If you landed, skidded and bounced off the end of the runway, throttled back up, turned around in the air, and landed again the other direction then took off, that's allowed.

If you flew past the runway without touching down, then turned around in the air, and landed only once and immediately took off again, then that's disqualifying.

Very nice run. It looks like you did the former so I am counting your time of 10:06.

[Pds314]

Well... that didn't go as planned...

[Pds314]

Almost successful run in 7:24 with a 900 charge, 900 ore plane. Tailstrike on landing broke an ore tank.

Edited March 5, 2020 by Pds314

[Pds314]

YES! Finally I completed my own challenge. 7:30 I ended up losing around 13 seconds at the end from skidding off the side of the runway and having to crawl back onto it.

Pre-flight checks. Note that while I have a 1000 EC battery, it only has 900 EC in it.


The run itself:

Spoiler

Takeoff, albeit off the side of the runway by accident. At this rate I will burn through my entire battery in 4 minutes.


Cutting back throttle. It's more efficient to go 180 the whole way than be forced down to 150 after an initial burst of 210.


The island approaches.


Coming up on the runway, trim off. SAS on.


I failed to take pictures mid-landing due to the difficulty of landing this vehicle correctly and then braking down to a safe speed. The large ailerons double as spoilers to keep the craft firmly bolted to the ground with downforce and to slow it down.


We don't bother stopping, just doing a tight turn with the landing gear. We do need to reduce prop pitch for takeoff though. Halfway point and EC is at just over 55%.


We need speed for takeoff. Full throttle. This would drain our remaining battery in about 1 minute, 40 seconds.


Dropping down to avoid as much loss of speed. Gear up. Trim on. Accelerate to cruise speed.


Cut throttle to avoid draining the battery too fast.


Actually, we've got charge to spare. Full throttle!


Charge!


Trim off.


Fastest speed during the run.


Activate spoilers. The plane flares into a stall/cobra 100 meters above the ground and smashes into the air to slow down.


Final approach. Gear down.


Skipped off the runway and got stuck next to it.


Wasted several seconds getting back onto the runway.

Aaand stopped on the runway in 7 minutes and 30 seconds!

Edited March 5, 2020 by Pds314

[Koolkei]

which engine is the electric prop engine?

 

[vyznev]

After seeing your entry, I realized that my plane had way more wing area than it really needed. So I cut it down. I also added one more pair of engines after realizing I had over 100 units of EC left after my first test flight. At this point, I think the limiting factor is actually my own piloting skill. I could probably save well over a minute just by landing faster.

Anyway, here's my new run. Final time 09:15. This time I even recorded a video!

Craft file: https://pastebin.com/BWU3NzvH

 

Edited March 5, 2020 by vyznev

[ralanboyle]

Alright, here is my 7:34 run. Not quite good enough to take the top but I am very confident I can go sub 7 minutes and maybe sub 6 minutes. We shall see... 

Edited March 6, 2020 by ralanboyle
Edit

[mystifeid]

Jagged this the first time I tried recording it but you can be the judge of whether it is acceptable. Came to a stop at KSC after 7:04. With so much weight, the landings are damn tricky. Plane is called "Nuthin Special".

 

Edited March 7, 2020 by mystifeid

[ralanboyle]

Congrats @mystifeid on having the first manned run. 

Here is my new run, stopping at 6:24. I still think I can break the 6 minute mark with some stability fixes and more aggressive landings. 

 

Edited March 9, 2020 by ralanboyle
Edit

[mystifeid]

Jeb slides to a stop at 5:56 in "Fat Boy" and is pretty sure he can go faster.

 

[ralanboyle]

Dang,

Looks like I need to revisit this. Though the OP might be gone... 

I'm glad to see you broke the 6 min mark. I knew it could be done. 

[mystifeid]

2 hours ago, ralanboyle said:

Though the OP might be gone... 

I doubt that. Probably has a life and has to juggle that with a KSP addiction.

2 hours ago, ralanboyle said:

I'm glad to see you broke the 6 min mark.

I was pretty happy too. Now 5m 30s would really be something ... I already have a 5:53 but it's not enough of an improvement. Think it's time for a redesign - something seems to be missing. Oh yeah. Moar engines!

Edited March 10, 2020 by mystifeid

[Pds314]

On 3/9/2020 at 7:10 PM, ralanboyle said:

Dang,

Looks like I need to revisit this. Though the OP might be gone... 

I'm glad to see you broke the 6 min mark. I knew it could be done. 

Am not gone.

Updating the leaderboard now.

Edited March 11, 2020 by Pds314

[Pds314]

On 3/5/2020 at 3:53 AM, Koolkei said:

which engine is the electric prop engine?

 

It's in Breaking Ground. Motors and prop blades. You can, however, use stock reaction wheels to build a different kind of electric prop plane, although I don't know that it will be very competitive, but if anyone enters something highly, highly unconventional like that, I will consider making a separate leaderboard for non-DLC craft, or helicopters, or non-DLC helicopters, or whatever weird off-meta builds.

It does look like the challenge at least slightly favors the heavier designs. I might try building one with like 6000 EC and 6000 Ore and see if I can't get a sub-6-minute run. Although landing it will be slightly terrifying.

Edited March 11, 2020 by Pds314

[mystifeid]

1 hour ago, Pds314 said:

Although landing it will be slightly terrifying.

Not necessarily - I think it depends on the wing loading. Look at how slowly and easily @ralanboyle is able to land nearly twice as much ore compared to me. Top speed is important - probably something around 250m/s is needed for 6 minutes - but so is power or how quickly you can accelerate to top speed. After that, the precision of the flight is everything. How smoothly you can change prop pitch especially while taking off and landing. How quickly you can land and come to a stop. (When I started I cursed using a tail dragger because of the terrible braking but I soon got used to skidding and realized it was probably an advantage).

I've had a lot of fun with this challenge so thank you.

[Pds314]

Regarding  stock electric props, it looks like the torque efficiency of single axis reaction wheels is somewhat better than that of a small motor at 460 RPM.

Small motor requires 1.6 EC/s at 460 rpm. Generates 20 kN*m. Efficiency: 12.5 kN*m/EC/s @460 RPM.

Small reaction wheel using one-axis torque requires 0.25 EC/s at all RPM. Generates 5 kN*m. Efficiency: 20.00 kN*m/EC/s.
Small reaction wheel using two-axis torque requires 0.5 EC/s at all RPM. Generates 7.07 kN*m. Efficiency: 14.14  kN*m/EC/s.
Small reaction wheel using three-axis torque requires 0.75 EC/s at all RPM. Generates 8.66 kN*m. Efficiency: 11.55 kN*m/EC/s.

However, the advantage in efficiency is offset by the much higher complexity, mass, and physical size of these reaction wheel motors.

That being said, mass of any competitive entry seems to go into the wing and ore mass. Not the engine mass. The complex controls and higher drag are a concern, but just adding a few hundred kg of reaction wheels probably is not.

Additionally, stock props like to be at full RPM 100% of the time. They do not benefit in lower energy consumption at lower RPM, so you're better keeping it at 460 RPM ore even slightly higher to get good efficiency.

The large 2.5m reaction wheels have an even more impressive 50 kN*m/EC/s. But they are quite large, and are only about 50% more powerful than a small motor. They do maintain a very impressive 28.87 kN*m/EC/s when used on all 3 axes though, and this does give them a more adequate 51.96 kN*m of torque, over 2.5 times that of a small motor.


---------------------------------------------------------------------------------------------------

When you manage to build a 15000 EC, 15000 Ore plane with not enough lift, nor energy, nor speed....

Edited March 11, 2020 by Pds314

[mystifeid]

It has been a surprise to find how much more efficient the ducted prop blades seem to be compared to the conventional ones. Is that just me? Or is that a thing now?

Remember that prop speed challenge? Top speeds around 300m/s ? Here is Fat Boy sans ore in a slight but steady climb. 323m/s !!

Makes you wonder what's possible now.

Edited March 11, 2020 by mystifeid

[Pds314]

6 hours ago, mystifeid said:

It has been a surprise to find how much more efficient the ducted prop blades seem to be compared to the conventional ones. Is that just me? Or is that a thing now?

Remember that prop speed challenge? Top speeds around 300m/s ? Here is Fat Boy sans ore in a slight but steady climb. 323m/s !!

Makes you wonder what's possible now.

Ducted fan blades are better at high speed.

[sturmhauke]

I wouldn't want to try this with old-school stock props. They're much more difficult to control, especially once you start getting into multi-engine designs. The blades also have a greater tendency to extend to a huge radius at operating speed, which isn't exactly landing-friendly.

[Pds314]

2 hours ago, sturmhauke said:

I wouldn't want to try this with old-school stock props. They're much more difficult to control, especially once you start getting into multi-engine designs. The blades also have a greater tendency to extend to a huge radius at operating speed, which isn't exactly landing-friendly.

I think hybrid designs might be competitive. Certainly without OP BG prop blades they would suffer.

[mystifeid]

Couple more tips. Make the turn into final to the island runway slightly below or at the height of the runway. And if you are aiming to land near the end of the KSC runway, make the turn into final above about 150m - below this height it's very hard to see the runway as you are approaching and even harder judging when to make the turn. These two things alone can save a lot of time.

Best time now at 5:44. Still in Fat Boy. It's interesting that in my last video above I still had 49 units of EC after coming to a stop. In that attempt the engine size was set to 50% in the hangar. So I've been increasing the engine size 1% at a time and going faster each time. Now with engine size at 54% my time is at 5:44 and I still have 39 units of EC remaining. Time to try 55%. (Why have EC remaining ? Because increasing prop pitch is very effective at reducing speed.)

Edited March 12, 2020 by mystifeid

[mystifeid]

Wow. Engines at 55% and 260+m/s top speed in level flight. Finished at 5:38 with 48 EC remaining.

Edited March 12, 2020 by mystifeid

[mystifeid]

After some minor tweaks to the suspension, brakes and engines - now at 56% - Jeb slides Fat Boy in at 5:34. This time Jeb has 95 EC remaining so sub-5m30s is definitely possible especially considering how less than optimal the landing at KSC is this time. Jeb has pulled off a very aggressive landing at the island runway though, which has made all the difference. But these are pretty tricky and in fact the whole flight is starting to have to be moderately perfect. The tension is getting to Jeb. Since this is now close to a minute faster than his nearest rival, that might have to be the end of it. (Unless some real competition turns up).

 

Edited March 12, 2020 by mystifeid