Fastest aircraft possible

[Pro100kerbonaut]

 

3:23-3:25 1751m/s

[Pro100kerbonaut]

http://imgur.com/rbNqgj2

1752 m/s

On 28.06.2016 at 1:00 PM, Gman_builder said:

 

5. It is required to fly for at least 15 minutes before running out of fuel.

 

Do gliding count as "flying"?

[*MajorTom*]

16 minutes ago, Pro100kerbonaut said:

http://imgur.com/rbNqgj2

1752 m/s

Do gliding count as "flying"?

p6 challange rules. 6.You must record your speed run as a LEVEL flight. I.E. No diving to gain speed or dropping out of orbit.

[Pro100kerbonaut]

attempt 2 is level flight

 

[*MajorTom*]

8 hours ago, Pro100kerbonaut said:

attempt 2 is level flight

 

I only have top speed 1702 m/s in 1.2.2 and average speed 1680 m/s . Something changed in 1.2.2 . I think even old craft can't  do they old results 

 

[Gman_builder]

@Pro100kerbonaut That was pretty quick but it broke 2 of the rules. did not fly for 15 minutes under power and you were descending in order to reach that speed. Level flight my guy. No cheating.

 

@*MajorTom* Same goes for you my dude.

18 hours ago, Stargate525 said:

When you say it needs to be able to fly for fifteen minutes, is that at full burn, or can we ramp up to speed, then pull back for the duration portion?

Well your craft will go faster with less fuel anyway, but honestly if your plane cant fly at full speed for only 15 minutes im gonna disqualify it. tbh its not that hard to do.

Edited December 24, 2016 by Gman_builder

[*MajorTom*]

12 minutes ago, Gman_builder said:

 

@*MajorTom* Same goes for you my dude.

Well your craft will go faster with less fuel anyway, but honestly if your plane cant fly at full speed for only 15 minutes im gonna disqualify it. tbh its not that hard to do.

yep, you are right in 3:11 fuel only for 6 minutes for top speed ... it can be in air for half of hour, but not in top speed... so I can try to build bigger ship  but later  

 

ps: i look at: "5. It is required to fly for at least 15 minutes before running out of fuel." and suppose it only can be in air for 15+ min and gain top speed in this interval... so sorry my facepalm

[Stargate525]

On 12/24/2016 at 2:30 PM, Gman_builder said:

@Pro100kerbonaut That was pretty quick but it broke 2 of the rules. did not fly for 15 minutes under power and you were descending in order to reach that speed. Level flight my guy. No cheating.

 

@*MajorTom* Same goes for you my dude.

Well your craft will go faster with less fuel anyway, but honestly if your plane cant fly at full speed for only 15 minutes im gonna disqualify it. tbh its not that hard to do.

Well yes. But it's less the fuel and more 'my plane will burn to a crisp at about 4 minutes.' xD

[Gman_builder]

1 hour ago, Stargate525 said:

Well yes. But it's less the fuel and more 'my plane will burn to a crisp at about 4 minutes.' xD

So then make it less flammable. Gotta follow the rules.

[foamyesque]

I've broken 1800m/s in level flight, but sustaining that for fifteen minutes is a real challenge.

[tseitsei89]

17 hours ago, foamyesque said:

I've broken 1800m/s in level flight, but sustaining that for fifteen minutes is a real challenge.

Wow! What sorcery are you using? All my tests indicate that rapier has a flame-out speed of 1751.8m/s. That is what I always achieved no matter what I did  Looking forward to see what you are doing to get 1800+m/s.

But for now I have this craft that can reach 1751.8m/s momentarily and maintain ~1748m/s speeds for a long time. And without any user input once leveled out too. If you are in level flight at ~20km and click prograde on SAS it will hold itself between 19.5km and 21km and between ~1746m/s - 1751.8m/s

I present you the Bat Out of Hell:

Video of 30 minutes flight and I still have fuel remaining and I only took ~1/3 of my fuel capacity on board to start with so this could go on for a long long time. The batteries that are about to blow up are completely unnecessary, I just forgot to take them out. So overheating won't be a problem for even longer flights either.

https://www.youtube.com/watch?v=OaY8s6iYOW4

Kerbal is in a command chair inside a fairing since cockpits got really explosive at those speeds...

Edited December 27, 2016 by tseitsei89

[foamyesque]

41 minutes ago, tseitsei89 said:

Wow! What sorcery are you using? All my tests indicate that rapier has a flame-out speed of 1751.8m/s. That is what I always achieved no matter what I did  Looking forward to see what you are doing to get 1800+m/s.

Going low, to take advantage of the higher speed of sound. The trouble is that the RAPIERs overheat...

[tseitsei89]

1 minute ago, foamyesque said:

Going low, to take advantage of the higher speed of sound. The trouble is that the RAPIERs overheat...

Ah, ok. I thought that would increase drag too much but apparently I was wrong

[foamyesque]

1 minute ago, tseitsei89 said:

Ah, ok. I thought that would increase drag too much but apparently I was wrong

Nah, it's thermal effects that are the killer. Also you burn fuel like crazy. :v

[Dynastic Labs]

On 24.12.2016 at 1:35 AM, Gman_builder said:

Do it then. I doubt it can break Mach 5.8   XD

It went 1400+ m/s before left engine mount blew up. Rip dude.

But Colossus 2 is in development.

Edited December 30, 2016 by Dynastic Labs

[Redshift OTF]

I've got a craft that can run at sustained speeds of 1850 m/s without blowing up however it wouldn't be able to run for 15 minutes as it has to fly under 500m and would run out of fuel too quickly. Running on infinite fuel the only thing that stopped it was when it flew into the next continent.

[Gman_builder]

On 12/27/2016 at 3:36 PM, foamyesque said:

Going low, to take advantage of the higher speed of sound. The trouble is that the RAPIERs overheat...

That makes no sense. Going lower would just increase drag, increase heating, and increase speed of sound. Which in turn would reduce your max Mach number. You should technically go slower or just explode unless you were in a dive and "reached your max speed" at the bottom of the dive.

[foamyesque]

1 hour ago, Gman_builder said:

That makes no sense. Going lower would just increase drag, increase heating, and increase speed of sound. Which in turn would reduce your max Mach number. You should technically go slower or just explode unless you were in a dive and "reached your max speed" at the bottom of the dive.

Engine thrust keys on Mach number. The same Mach number ASL corresponds to a higher indicated airspeed, and the thrust curve of the rapiers is such that their thrust increases faster than drag as you get closer to sea level as a result of both that and the altitude adjustment.

[Redshift OTF]

Here is my latest attempt. Top speed was 2016.1 m/s but it could probably go faster.

It does have wings, 2 x Wing Strakes, but I had to move them in to keep them protected by the heat shield. They are enough to allow the craft to take off from the runway so they should count. As you can see from the video, thrust drops dramatically after 2000 m/s which extends the flight time beyond 15 minutes.

Any questions or if anyone wants the craft file just ask.

[tseitsei89]

1 hour ago, Redshift OTF said:

Here is my latest attempt. Top speed was 2016.1 m/s but it could probably go faster.

It does have wings, 2 x Wing Strakes, but I had to move them in to keep them protected by the heat shield. They are enough to allow the craft to take off from the runway so they should count. As you can see from the video, thrust drops dramatically after 2000 m/s which extends the flight time beyond 15 minutes.

Any questions or if anyone wants the craft file just ask.

Damn! Just as I was uploading my ~1800 m/s entry

Well done!

[Redshift OTF]

1 hour ago, tseitsei89 said:

Damn! Just as I was uploading my ~1800 m/s entry

Well done!

Thanks! I think if you use the same tricks I did you could do a faster one, especially if more engines are used. The main thing is the drag model is based on which attachment points parts are connected to while the heat model is based on which part is at the front. Adding a cone to a heat shield and then moving it back somewhere safe gives good heat protection without the heat shield creating much drag.

[tseitsei89]

23 hours ago, Redshift OTF said:

Thanks! I think if you use the same tricks I did you could do a faster one, especially if more engines are used. The main thing is the drag model is based on which attachment points parts are connected to while the heat model is based on which part is at the front. Adding a cone to a heat shield and then moving it back somewhere safe gives good heat protection without the heat shield creating much drag.

Yep and that is the exact reason why I wont try to beat it. It is starting to need part clipping and 'cheating' the physics engine.

And 'cheating' the game engine isnt something I like doing. I like finding the limits but limits for me are the ones without any of this funny business like clipping and/or hiding the drag of some parts.

But as I said well done. I appreciate what you have done but it isnt something I'm interested in doing since you are using tricks that I consider forbidden in my own game because of some "RP" reasons.

[*MajorTom*]

On 31.12.2016 at 3:33 PM, Redshift OTF said:

Here is my latest attempt. Top speed was 2016.1 m/s but it could probably go faster.

It does have wings, 2 x Wing Strakes, but I had to move them in to keep them protected by the heat shield. They are enough to allow the craft to take off from the runway so they should count. As you can see from the video, thrust drops dramatically after 2000 m/s which extends the flight time beyond 15 minutes.

Any questions or if anyone wants the craft file just ask.

and it burn 1 poin of fuel every sec at top speed... so it burn all 600-700 in 10-13 min (not 15). It great speed craft! but not for this challange I think is in it? And if you slow down and it burn lesser fuel can it normal fly (lift force) and at what speed to fly 15 min?

[tseitsei89]

8 hours ago, *MajorTom* said:

and it burn 1 poin of fuel every sec at top speed... so it burn all 600-700 in 10-13 min (not 15). It great speed craft! but not for this challange I think is in it? And if you slow down and it burn lesser fuel can it normal fly (lift force) and at what speed to fly 15 min?

Even though your numbers are a bit off I believe you might be actually correct...

If we look at the very end of the video(where the F3 menu is visible) we see that:

1. Craft has 618 units of LF left

2. The craft is burning 0.84424 units of LF per second (see the RAPIER window on the left and notice that it also approves with the number on the top right corner).

3. The craft has been flying 2minutes and 35seconds at this point.

No let's see. 618 units / 0.84424units/s = 732.019s = 12.200min = 12minutes 12seconds.

And flight time to that point is 2min35s and the remaining flight time is 12min12s so total flight time would be 2min35s + 12min12s = 14min47s which I think is still reasonably close to 15min so we could assume that it is capable of that flight time BUT once we notice that it took more than 1min30s to actually reach top speed we can pretty safely assume that the craft runs out of fuel before it has remained it's top speed for 15mins.

And the other possible problem I noticed while taking a closer look are possible overheating problems. It only has 172 units of ablator left at the end of the video and is using 0.39units/s so that means it only has ablator left for about 172/0.39 = 441s = 7mins 21s. Now I dont know if the heatshield is capable of surviving those speeds without any ablator left for several minutes of flight still remaining, but at least that is a very possible problem and needs further testing/proof.

EDIT: @Redshift OTF I'm not accusing you of cheating or anything I just think these might be some things you honestly missed during testing.  But if I am wrong for some reason with my calculations/reasoning I apologize...

Edited January 4, 2017 by tseitsei89

[Redshift OTF]

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.