15 km and back Juno race.

[Pds314]

The aim of this challenge is to take off from the runway in a plane powered only by Junos, reach an altitude of 15 kilometers, and then return to the runway in as little time as possible.

 

Rules:

1. To limit the efficacy of engine spam, the thrust limiter setting on the Junos must be set at or below the square root of the inverse of the engine count. I.E.

1 Juno = maximum thrust limiter of 100%

2 Junos = maximum thrust limiter of 70.5%.

3 Junos = maximum thrust limiter of 57.5%.

4 Junos = maximum thrust limiter of 50%

5 Junos = maximum thrust limiter of 44.5%

6 Junos = maximum thrust limiter of 40.5%

7 Junos = maximum thrust limiter of 37.5%

8 Junos = maximum thrust limiter of 35.0%

9 Junos = maximum thrust limiter of 33.0%

10 Junos = maximum thrust limiter of 31.5%

and etc and etc.

 

2. You may not discard or break engines or cockpits. Everything else is fair game. You must have a Kerbal in a cockpit. Not a chair or a probe.

 

3. You must takeoff and land horizontally, and must start and end at below 1.0 m/s on the runway. Note that this doesn't mean you can't use the grass or water as a takeoff landing site, just that if you do, you need to taxi to/from the runway.

 

4. No parachutes.

 

5. Limit clipping to the sensible. Don't clip full fuel tanks deep into full fuel tanks or engines deep into engines.

 

6. No aero exploits. This means that if there's a big flat surface facing into the wind, it should be generating drag like one. Anything where you rotate or offset parts to obstruct a node in an unreasonable manner is an aero exploit. You should of course feel free to optimize aerodynamics as much as you like in non-exploitative ways.

Edited November 14, 2020 by Pds314

[ralanboyle]

Ok cool, 

My first try comes in at 3:53. Beat it so I have an excuse to make it better. 

 

[AHHans]

3 hours ago, ralanboyle said:

My first try comes in at 3:53. Beat it so I have an excuse to make it better. 

Not sure if it can be done. I added a pair of small nose cones + junos to what I think your craft is (What Is your main wing? A modded part?) and got a lower TWR after setting the thrust limiters.

[ralanboyle]

30 minutes ago, AHHans said:

Not sure if it can be done. I added a pair of small nose cones + junos to what I think your craft is (What Is your main wing? A modded part?) and got a lower TWR after setting the thrust limiters.

No modded parts. My wing is a pair of the small  triangles attached in symmetry and slid together. One could shave some seconds off my run with my ship with a better approach and landing. There is probably also room for a higher TWR which will get you up and down faster. 

[AHHans]

38 minutes ago, ralanboyle said:

No modded parts. My wing is a pair of the small  triangles attached in symmetry and slid together.

Ah, O.K. It looked like one part to me. But two of those together have the same lift and mass as one Small Delta Wing which I used, so my results don't change.

Saving a few seconds through an optimized flight profile is probably possible, but a higher TWR is going to be hard!

[Pds314]

7 hours ago, ralanboyle said:

Ok cool, 

My first try comes in at 3:53. Beat it so I have an excuse to make it better. 

 

Wait whoops I must've deleted the rule about requiring the use of a cockpit while formatting the OP. I'm so sorry.

 

Unfortunately I cannot qualify this entry even though it fit rules as written because it would be clearly unbeatable and the rules as written wouldn't have been very interesting and would essentially just be a probe weight saving fight and nothing else. You're not supposed to be able to just go straight up with a TWR of like 5 or there would be little point.

 

The goal of the challenge isn't just to make a tiny drone with perfect execution and fly it a second faster than someone else in a sounding-rocket-like vertical ascent profile but rather to climb with a crewed airplane that can't just go straight up except maybe at sea level. So you need to be concerned about many factors besides TWR and going straight up from the ground just won't be possible, since the best sealevel TWR you could probably achieve with horizontal takeoff is about 2.0, and that will drop to below one at even 8 km altitude. But if you just make a minimalist cockpit with engines sort of plane you will have a lot of difficulty ascending any further, thus is born a trade off between having a high TWR, having a high maximum speed, having a good L/D, being able to convert horizontal speed into altitude, functioning well both at sea level and in the rarefied atmosphere of nearly 20 km up, and being able to actually land the thing quickly. Among other things like what profile you should actually fly.

Edited November 13, 2020 by Pds314

[ralanboyle]

@Pds314 Are you sure this is possible? 

[Pds314]

5 hours ago, ralanboyle said:

@Pds314 Are you sure this is possible? 

I seem to recall doing missions with those settings and very minimal numbers of Junos but alas. It might be too difficult. I can't maintain level above 14 km.

 

Maybe I will change the challenge. 

Ok. I adjusted it because I don't want it to be only hyper-specialized giant-winged monstrosities. Climbing to 15 km is definitely doable for most Juno aircraft. Or, well, of they're at all designed for the mission. Replicas might struggle.

Edited November 14, 2020 by Pds314

[ralanboyle]

4 minutes ago, Pds314 said:

I seem to recall doing missions with those settings and very minimal numbers of Junos but alas. It might be too difficult. I can't maintain level above 14 km.

 

Maybe I will change the challenge. 

Ok. I adjusted it because I don't want it to be only hyper-specialized giant-winged monstrosities. Climbing to 15 km is definitely doable for most Juno aircraft.

Perfect, I think this will be more competitive. If 20km is possible within your requirements, it'll only be achievable to a very few pilots. The Juno flames out at just over 18km, so it's all inertia after that. 

[Pds314]

1 hour ago, ralanboyle said:

Perfect, I think this will be more competitive. If 20km is possible within your requirements, it'll only be achievable to a very few pilots. The Juno flames out at just over 18km, so it's all inertia after that. 

Yeah. Kinda funny because crafts using a trio of Derwent Vs in RP-1 can easily do straight and level at supersonic speeds and 19 km even with pretty heavy craft. Although the atmospheric pressure is an issue in early cockpits. I guess Earth's atmosphere and FAR probably help a lot.

Edited November 14, 2020 by Pds314

[Pds314]

Ok. I have an entry. It should be pretty beatable though. 11:23

I used a 5-engine plane and my first attempt to zoom climb to 15 km was about 350 meters short, so I got there on my second attempt.

Edited November 14, 2020 by Pds314

[ralanboyle]

very nice, what kind of ascent profile did you use? Apparently i suck at this. 

[Pds314]

7 hours ago, ralanboyle said:

very nice, what kind of ascent profile did you use? Apparently i suck at this. 

Ok so I pretty much just flew straight until 300 m/s, then ascended at constant-ish speed to 9000 meters, and did a failed zoom climb, flew back down to 12000 meters and regained to 280 m/s before a second zoom climb.

Edited November 14, 2020 by Pds314

[Flying dutchman]

10:28

 

3 juno engines and just enough fuel, i took off in the 90 degree direction and when i was at about 12km i turned around so that when i hit 15km i would be fairly close to the ksc and could pretty much just dive straight down. then at the very last moment i used a split rudder as an airbrake to slow down and land safely

 

Edited November 14, 2020 by Flying dutchman

[swjr-swis]

I'm not sure how I missed this one , but seeing as I was just tinkering with fast little Juno planes for another challenge, I might as well file an entry to this one too.

The Juno15K II, a dual-Juno plane that races to 15km and back to a safe stop on the KSC runway in exactly 10:00.

The flight profile is a low climb rate (by holding SAS Hold) off the runway in favour of acceleration, and only pitching up slightly once enough speed is built up to exchange for altitude (around 8km going Mach 1.4). Then just haul back full throttle and use the eye-popping airbraking capabilities of an opened service bay to slow down at the very last moment.

 

 

 

Full album of this speedrun, including the flight summary: https://imgur.com/a/FwDycvZ

Craft file: Juno15K II (hosted on KerbalX)

Edited February 20, 2021 by swjr-swis
flight profile