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An interesting discovery regarding an intake...

Unplanned Stoichiometry

By Unplanned Stoichiometry
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Unplanned Stoichiometry

Unplanned Stoichiometry

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I was doing some meter-level low flying with one of my more acrobatic jets. Eventually, of course, I crashed. However, I noticed that part of the jet kept on sliding, perfectly stably, along the ground at over 150 m/s. I threw together a quick jet sled, and yep: The Mk1 Diverterless Supersonic Intake is indestructible when sliding on its intake.

Here is that jet sled sliding along the ground at nearly 900 m/s (any more and the Panther would explode from overheating!).

 https://imgur.com/a/wJaKi

These intakes don't just withstand the tear-your-face-off levels of sliding. I've taken this sled for a jaunt around the KSC, including the hills to the west, and it can land on those intakes quite hard.

Has anyone else seen this behavior? Can someone confirm it? I'm running a mostly-stock install. My mods are Hyperedit, Kerbal Engineer Redux, Vessel Mover, and Tweakscale (not used for this sled). I highly doubt those would cause these intakes to be indestructible, so it should be repeatable. If it is repeatable, then I wonder if this has some application outside of setting sled speed records?

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Unplanned Stoichiometry

Unplanned Stoichiometry

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On 1/19/2018 at 8:03 PM, Dfthu said:

Isnt the polar ice caps perfectly flat? If so I think its not exploding because its not impacting the ground? so it should work with any part?

That's correct; I have tested with other parts. The unique thing about this one is that it is also highly resistant to impact. One can land on it after hitting the ground going 150 m/s and it'll be fine. I checked by using the hills to the west of the KSC as ramps. Slid right up like a champ and landed hard, perfectly fine (other than the nose cone exploding). There'll be some glitchy spasms, but the intake won't explode. The same can't be said about, well, anything else I've tried.

That impact resistance is necessary for high-speed sledding. When sliding along the ground, it's only a matter of time before one catches... something, causing a collision. Do those somethings possibly have to do with KSP's terrain-loading model? I don't know. In any case, other parts would explode long before they reach those speeds.

If you try this yourself (and you'll have to until I figure out how to insert videos), you may notice that the intake spasms, and it gets more frequent at high speeds. Since the same thing happened on impact with the ground after landing, I'm fairly certain that each one of those spasms is the intake catching a terrain feature and colliding with it at Mach 3, at which is slightly higher than the 10 m/s rated impact tolerance, and surviving. One might recognize that spazzy behavior from playing around with "Ignore Crash Damage".

Oh, another interesting thing is that if I try to pull up while sledding, at least one intake remains stuck to the ground. It would appear that it's not just not colliding - it's embedded in the terrain.

On 1/20/2018 at 1:07 PM, SpacedCowboy said:

That's pretty cool! You should be getting a slight amount of lift from those wing connectors. You ought to try that thing out on the Minmus flats.

BTW, Welcome to the forums.

Thanks for the welcome! I used the wings for stability. After what I described above, I don't think the lift makes a difference. But I think I can do you one better than Minmus's flats: I'll just turn off air drag and max temperature in the cheats menu! After all, on Minmus, past 150 m/s, even gravity wouldn't be strong enough to hold this sled down.

[1 minute later] Well, that didn't do much for speed - the microcollisions kept the sled at a mere 1000 m/s. :(

One issue with the sled is that if any other parts contact the ground (fairly likely, with the amount of spazzing) the entire sled RUDs. In addition, if any part of the intake except for the actual inlet touches the ground, the same thing happens. I'll try and devise some silly-looking runners to prevent that from happening, but for now, I think that's a good weekend's work.

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Shadowmage

Shadowmage

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This is caused by a quirk in the stock collision behavior.

Parts can have multiple separate colliders.  Only one of those colliders will trigger explosions.  So, in this case, the cylinder collider of the intake is likely the explosion-trigger, while the lower protrusion is likely non-exploding.

However in some instances, you can get a 'phase-through' effect, where the explosion-triggering-colliders will sometimes still register hits and cause explosions -- this depends on trajectory and velocity mostly (see - 'collider punch-through').

(I would term this as a bug;  I've already reported it to Squad back during the 1.2 update, and again during the 1.3 update; they ignored it completely both times... so perhaps it is an 'intentional bug' or whatever you would call it)

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