Fastest aircraft possible

[tseitsei89]

34 minutes ago, Redshift OTF said:

Heh, don't worry, I can take criticism. At least the craft is interesting enough to get responses!

Regarding flight time, I was just going by what Mechjeb says. It says I have over 15 mins left of fuel at top speed and it had already flown for a minute and a half before that so I figured that was good enough for the 15 minute total flight time rule. Bear in mind that the craft will get lighter as it uses fuel which will make it go faster and this will lower the thrust meaning the craft shouldn't be burning the same amount of fuel later on.

The heat shield ablator will run out before 15 mins but it seems to still protect the rest of the craft from heat which is its main purpose. I don't know how long it will last before its own heat build up lasts which would destroy it and expose the rest of the craft but its internal temp is 3300 K which is pretty big. Perhaps I should have enabled the heat debug figures in the menu to see how fast it was heating up but it wasn't something I could practically test. The main problem with the craft is you have to fly low to get that amount of thrust from a Rapier engine and as you can't really steer a plane at near orbital speeds you end up flying into a continent before 15 mins is up.

And yes, you can fly the craft like a normal plane. A pair of control surfaces and 2 wing strakes are easily enough to fly something that weighs 8.455 tons. You can see the lift it generates on the runway as it is taking off.

Hope that helps. I think the craft was in the spirit of the challenge any how. And it was interesting to see what the upper limits of a Rapier engine can do.

That's good then

But speaking of the flight time I think that the craft getting lighter has quite a little impact here only. Because the area facing forward will remain the same the drag force trying to brake down the craft will remain the same. And since you are moving at constant velocity here you should counter that force with your thrust --> your thrust must also remain pretty much the same during the whole top speed part of the flight even though your craft IS definitely getting lighter.

 As for the overheating issues. Yes I havent tested it but that was just something I noticed and yes 3300K is very high but so is 2000 m/s at sealevel  But it might still be survuvable  

Very nice craft anyway.

[TheKorbinjer]

My F-104 Starfighter is capable of 1,550 m/s ASL. Uses 3 engines clipped into 1 :3

[NightshineRecorralis]

https://www.youtube.com/watch?v=f1qZzSExXSM

I'll upload my attempt soon, it can reach 1700m/s+. Hopefully a real contender once I trim the fuel load.

Edited January 16, 2017 by NightshineRecorralis

[Jarin]

1734 should get me on the board. Gonna try a different wing setup to see if I can squeeze out a few more m/s.

Edit: 1740, same craft 20 minutes later, passing KSC after having circumnavigated Kerbin.

 

 

Edited January 18, 2017 by Jarin

[Jarin]

Edit: I suspect I've found the top speeds physically possible in stock, which is kinda disappointing from a challenge point of view, but what can you do?

Edited January 20, 2017 by Jarin

[Cunjo Carl]

On 1/20/2017 at 1:26 AM, Jarin said:

Edit: I suspect I've found the top speeds physically possible in stock, which is kinda disappointing from a challenge point of view, but what can you do?

Yeah, unfortunately the rapier tops out at mach 6, all's we can do is come asymptotically close. Your mach 5.85 is quite good, by the way! There are a couple interesting wrinkles in the story, though...

The Wheesley doesn't drop to 0 at the end of its engine curve, so it can maintain thrust indefinately! Unfortunately, it doesn't work at altitudes high enough to make it feasible.

You can also make planes with NERV engines rather than air breathers. With NERV engines you can go so fast you actually need to use your wing lift to keep down on Kerbin and not fly off into orbit! It's not the most efficient way to fly around, but it's undoubtedly fun... Let me dig up that old challenge in case you're interested... Escape Velocity: The Hypersonic Race

Again, nice plane. It looks like you kept it just shy of melting during flight, must have been tricky!

 

 

[Jarin]

1 hour ago, Cunjo Carl said:

It looks like you kept it just shy of melting during flight, must have been tricky!

The real trick was keeping it from melting on ascent. Had to keep it at like 1/5 throttle below 17km. Once up high, it seemed to handle itself pretty well (once I found a fix for the little "mk1 cockpit exploding" issue anyway). Turning on infinite resources keeps the rapiers from cutting out, and I've pushed it close to 2200 (edit: can hit 2250, but eventually hits heat saturation as internal temp climbs)  without any structural failure. Interestingly, the rapier thrust curve actually goes up on the other side of its cutoff point. It takes a minute to accelerate from 1720 to 1740, but like 10 seconds to accelerate from 1780 to 2100. 

Edited January 21, 2017 by Jarin

[Cunjo Carl]

4 hours ago, Jarin said:

The real trick was keeping it from melting on ascent. Had to keep it at like 1/5 throttle below 17km. Once up high, it seemed to handle itself pretty well (once I found a fix for the little "mk1 cockpit exploding" issue anyway). Turning on infinite resources keeps the rapiers from cutting out, and I've pushed it close to 2200 (edit: can hit 2250, but eventually hits heat saturation as internal temp climbs)  without any structural failure. Interestingly, the rapier thrust curve actually goes up on the other side of its cutoff point. It takes a minute to accelerate from 1720 to 1740, but like 10 seconds to accelerate from 1780 to 2100. 

 

They actually properly set the thrust to stay at 0 on the rapier (unfortunately  )... It might be cutting over into rocket mode for you? If you have the infinite resources cheat on it might be able to do that even without Ox on board, I'm not sure.

On the other hand if it's not in rocket mode you've found a fantastic little bug! I haven't played anything since 1.1.2, so it could well be. That would be exciting.

[Jarin]

38 minutes ago, Cunjo Carl said:

It might be cutting over into rocket mode for you?

... can you have infinite of a resource that there's no storage for? I think I had it on manual switching, but I didn't even think to check, and that thrust kick would be consistent with mode-switch. 

Ah well, I was mostly trying to test heat tolerance, so knowing the design can handle anything airbreathing engines can do is useful. Now to toss on some mod scramjets to see how it handles.

[drtricky]

Well, this SSTO I built managed to achieve this speed on a service run with all NERV engines off, if that counts for anything. 

Spoiler

 

[Wanderfound]

Not quite a winner (1,743.8m/s), but up in the running and doing it with style:

Album at http://imgur.com/a/H3z2y

Craft file at https://www.dropbox.com/s/s7l2m9vkgcxot4f/Kerbodyne Fireball.craft?dl=0

[Nefrums]

Was there any rule about what planet you had to fly on?

 

[Fett2oo5]

I would like some help further developing a Transcontinental aircraft, and application for this challenge.  I've been trying to build a Mach7+ aircraft both stock and/or with mod parts (expressly the [1.3.0] OPT Space Plane v2.0.1 mod and it's Scramjet engine),  FAR mod not installed.
However I'm running into thermal problems.  Using OPT Scramjet engines, I can't get any cockpit to withstand the temperatures at around 2100-2150m/s

Below is the best I can get from stock parts  (KSP version 1.3.1).  Additionally, imgur album: https://imgur.com/a/yKLY0

 

Does anyone have some advise for me to:
1. Build a plane that will achieve Mach 7, 8, or 9, in atmosphere.

2. Build a plane that will achieve Mach 7+ and the cockpit not explode due to max temp.

I'm looking forward to your helpful advise.

p.s. I am aware it is possible and easier to go faster at higher altitudes, however, for the plane pictured above, this craft achieved a higher speed at low altitude with the RAPIER engines by a difference of 200m/s.

 

Edited April 4, 2018 by Fett2oo5

[Fett2oo5]

I may have found a limitation...
(If this information is accurate) I found this on the KSP Wiki for the RAPIER engine:
" On the other hand, it delivers better performance than the J-X4 "Whiplash" Turbo Ramjet Engine at high speeds (~1000 m/s and higher) and altitudes (~17 km and higher), making it a good choice for high-speed atmospheric flight. Top speed is ~2,100 m/s in kerbins atmosphere(mach 6.2) "

Does anyone have any advise for achieving Mach 7 and beyond?

[Gman_builder]

On 4/5/2018 at 8:48 AM, Fett2oo5 said:

I may have found a limitation...
(If this information is accurate) I found this on the KSP Wiki for the RAPIER engine:
" On the other hand, it delivers better performance than the J-X4 "Whiplash" Turbo Ramjet Engine at high speeds (~1000 m/s and higher) and altitudes (~17 km and higher), making it a good choice for high-speed atmospheric flight. Top speed is ~2,100 m/s in kerbins atmosphere(mach 6.2) "

Does anyone have any advise for achieving Mach 7 and beyond?

well it seems like 2,100 might be as fast as we can go. Id say getting as close to that as possible is a cool challenge.