Jetboat Speed Record.

[Pds314]

How fast can you get a boat powered solely by jets to go? Must be crewed. Crew and jets must survive.

Aerodynamic surfaces are allowed, but please ensure you are not even close to lifting off.

Records:

1. 1333 m/s, provisional, Platopoes

1. 354 m/s, purpleivan

2. 125 m/s, Platopoes

 

Edited May 23, 2020 by Pds314

[doggonemess]

I have never made a boat that worked. I made a submersible drone once, and it mostly worked. I'm not sure what I'm doing wrong that makes the boat destroy itself the instant it gets into the water. I can't imagine going 10 m/s, let alone 240.

[Pds314]

3 hours ago, doggonemess said:

I have never made a boat that worked. I made a submersible drone once, and it mostly worked. I'm not sure what I'm doing wrong that makes the boat destroy itself the instant it gets into the water. I can't imagine going 10 m/s, let alone 240.

1. Don't enter the water at high speed or steep angles.

2. When in doubt add bigger/more floatation devices.

3. Make sure the boat is not going to fall over by putting floats on all sides of the center of mass.

4. Once you have a boat, minimize the number of parts touching the water, especially those mostly submerged, to make it faster. Fairings, especially sizes bigger than 1.25m because you can autostrut then effectively, work well.

Edited May 18, 2020 by Pds314

[doggonemess]

Thanks for the info! I'm going to give it another shot.

[doggonemess]

How about mods? I love the parts in OPT, some are perfect for boat-like shapes. If not, no big deal. It's fun either way.

[Pds314]

4 hours ago, doggonemess said:

How about mods? I love the parts in OPT, some are perfect for boat-like shapes. If not, no big deal. It's fun either way.

Eh. I would say probably not mods. Sorry. You can always show a pic of a mod vehicle but many mods are not balanced.

[purpleivan]

After @Pds314 extolled the virtues of farings as boat hulls in the Kayak Club thread, I decided to have a go at this with an "everything in the fairing" type of design. That did mean of course that Jeb was flying blind.

I managed a speed of 354m/s which was at the moment the fuel ran out, which was pretty lucky as that's the limit of this boat before it transforms into shrapnel.

I had a go at letting the thing run as fast as it can and see what happens. Turned out that at 355m/s the fairing shatters, followed soon after by the rest of the boat.

It looks like at that speed the thing becomes unstable and gains air for a moment, as KER's Situation display changes to "Flying Low" for a split second befor the thing shatters.

Edited May 22, 2020 by purpleivan

[doggonemess]

8 hours ago, purpleivan said:

It looks like at that speed the thing becomes unstable and gains air for a moment, as KER's Situation display changes to "Flying Low" for a split second for the thing shatters.

It would be like tripping on the surface of a super-Earth. One moment you're standing, the next you're a pile of goo.

[Klapaucius]

On 5/19/2020 at 2:51 AM, doggonemess said:

I have never made a boat that worked. I made a submersible drone once, and it mostly worked. I'm not sure what I'm doing wrong that makes the boat destroy itself the instant it gets into the water. I can't imagine going 10 m/s, let alone 240.

If you have Making History, the Mission Builder allows you to place a craft directly on the water. It saves you heaps of time in testing and eliminates having to do the tedious taxi down the runway.

[Pds314]

4 hours ago, Klapaucius said:

If you have Making History, the Mission Builder allows you to place a craft directly on the water. It saves you heaps of time in testing and eliminates having to do the tedious taxi down the runway.

You don't need MH. Even 1.9 stock set position cheat will do.

16 hours ago, purpleivan said:

After @Pds314 extolled the virtues of farings as boat hulls in the Kayak Club thread, I decided to have a go at this with an "everything in the fairing" type of design. That did mean of course that Jeb was flying blind.

I managed a speed of 354m/s which was at the moment the fuel ran out, which was pretty lucky as that's the limit of this boat before it transforms into shrapnel.

I had a go at letting the thing run as fast as it can and see what happens. Turned out that at 355m/s the fairing shatters, followed soon after by the rest of the boat.

It looks like at that speed the thing becomes unstable and gains air for a moment, as KER's Situation display changes to "Flying Low" for a split second for the thing shatters.

Really impressed you managed that on just 3 Panthers. That's over mach, on water, with a sane number of jets.

Edited May 22, 2020 by Pds314

[purpleivan]

This is what's under the fairing. The front tank had a small amount (120 units I think) of fuel when dropped in the water, the others were empty. I started out with a lot of fuel (no idea why), then didn't get around to removing or replacing the empty tanks later. The big SAS module is in there with the idea that it wouldn't hurt to have it... except for the mass of course.

[Platapoes]

First attempt - 125.0 m/s, I'll update when I get better lol. I've never made boats before so I'm learning as I go.

 

 

Edited May 22, 2020 by Platapoes
Image embed didn't work previously, added image

[Platapoes]

Got to 310 m/s and decided I could do better, here's the result:

 

Just shy of 1333 m/s! I've hopefully got a video coming soon

 

Careful analysis of the video reveals the fairing actually disintegrated at 1303.9 m/s, after that it fell to the water. The highest speed should be 1303.9, and not 1332.9 m/s. Whoops.

[Pds314]

10 minutes ago, Platapoes said:

Got to 310 m/s and decided I could do better, here's the result:

 

Just shy of 1333 m/s! I've hopefully got a video coming soon

 

Careful analysis of the video reveals the fairing actually disintegrated at 1303.9 m/s, after that it fell to the water. The highest speed should be 1303.9, and not 1332.9 m/s. Whoops.

Is that with jet engines and did the jets and Kerbal survive???

[Platapoes]

It's using 4 Whiplash engines and the crew capsule did survive. I'm going to try and get a recording of it today. Once I pass around 340 m/s the engines become more efficient and it really accelerates. I might back off to try and guarantee survival, last time it took a lot of tries to get it right, although the engines sit lower than the capsule so they seem to take the impact.

Oh whoops I missed the jets surviving part  I'll have to get it again now anyway

[Platapoes]

I've gotten to 655 m/s and down again with everything (and everyone) surviving, using the same build.

[Platapoes]

 

Here's the last successful attempt - 731 m/s. Anything past that seems to crash as soon as I slow down!