Fastest Plane under 1.000m. [WE HAVE REACHED MACH 5!, Tidus Klein at 1,714 m/s]

[TheHengeProphet]

This challenge is truely the philosophical opposite to the Maching Bird Challege... It's not about how much air you can force through you, but how much you can force yourself through the air!

I've been trying my hand at this, and I have to say that it is quite difficult to get some decent speeds AND remain below 1000 meters. 854 m/s amounts to my best effort, and that was with wings literally made of Saber-S engines... I destroyed that craft file, because I don't want to look upon that horror ever again.

As a result, I have found that a singular radial intake is enough to feed upwards of twelve engines of any aspirated variety, at this altitude.

On another note, I have found that lifting bodies do function, with FAR, and it is possible to make a plane that uses them, but as such would violate your rules for not using "wings" in a more traditional sense.

I must say that lifting bodies can be tricky to land, but it's possible.

[Hejnfelt]

This challenge is truely the philosophical opposite to the Maching Bird Challege... It's not about how much air you can force through you, but how much you can force yourself through the air!

I've been trying my hand at this, and I have to say that it is quite difficult to get some decent speeds AND remain below 1000 meters. 854 m/s amounts to my best effort, and that was with wings literally made of Saber-S engines... I destroyed that craft file, because I don't want to look upon that horror ever again.

As a result, I have found that a singular radial intake is enough to feed upwards of twelve engines of any aspirated variety, at this altitude.

On another note, I have found that lifting bodies do function, with FAR, and it is possible to make a plane that uses them, but as such would violate your rules for not using "wings" in a more traditional sense.

I must say that lifting bodies can be tricky to land, but it's possible.

Absolutely agree on the philosophical opposite and I have learned so much new about aircraft design simply by being part of this challenge, pushing the boundaries.

About the radial intake, it can actually support more than 12 depending on the engine of course. As speed increases, so does the efficiency of the intake.

In my 1029 m/s video you'll see that I support 16 engines at takeoff whereafter 1 engine flames out and then comes back on again later as the efficiency of the intake increases with speed for a total support of 17 engines.

[m1sz]

This challenge is truely the philosophical opposite to the Maching Bird Challege... It's not about how much air you can force through you, but how much you can force yourself through the air!

I've been trying my hand at this, and I have to say that it is quite difficult to get some decent speeds AND remain below 1000 meters. 854 m/s amounts to my best effort, and that was with wings literally made of Saber-S engines... I destroyed that craft file, because I don't want to look upon that horror ever again.

As a result, I have found that a singular radial intake is enough to feed upwards of twelve engines of any aspirated variety, at this altitude.

On another note, I have found that lifting bodies do function, with FAR, and it is possible to make a plane that uses them, but as such would violate your rules for not using "wings" in a more traditional sense.

I must say that lifting bodies can be tricky to land, but it's possible.

Yes, im so proud of everyone trying out this challenge. Newcomers will surely feel overwelmed by the current records, and the masive competition between Sevant and Hejnfelt, two truly speedmonsters.

Btw, there is a rule so any plane has to have atleast 2 lifting surfaces, to avoid atmospheric rockets taking the place here!

About the land in the runway,if the plane seems undoubtedly capable of landing, is good enough!, in real life, they would have drag chutes (wich you can use with realchutes mod I think!)

[leaderboard updated at night! (CET time-european)]

[Sevant]

An hour of tinkering and I can go 5 m/s faster...the law of diminishing returns is rearing its ugly head.

[TheHengeProphet]

Query: Is the Procedural Dynamic Wings mod allowed? I figure it would fall under Procedural Dynamics.

Also, is it allowable to climb above 1km after achieving maximum velocity to facilitate greater ease in landing?

[m1sz]

Query: Is the Procedural Dynamic Wings mod allowed? I figure it would fall under Procedural Dynamics.

Also, is it allowable to climb above 1km after achieving maximum velocity to facilitate greater ease in landing?

Yes, pwings are allowed, and yes, you can climb abobe 1km after archieving maximum velocity, but then you have to show proof of your speed using video or pictures. It's not allowed to dive, but anyway, at the current speed record, I dont think it's possible to dive at all

[Hejnfelt]

Yes, pwings are allowed, and yes, you can climb abobe 1km after archieving maximum velocity, but then you have to show proof of your speed using video or pictures. It's not allowed to dive, but anyway, at the current speed record, I dont think it's possible to dive at all

I'd like to point out that slowing down from above mach 3.5 below 1000km is becoming even more of a challenge than actually achieving the speed. At present moment I have designs which can reach mach 4 but cannot slow down due to instability from sudden lack of thrust and resulting complete disintegration

Allowing people to climb above the 1km ceiling, greatly reduces the complexity of this challenge as all you have to do is climb until either your engines lose thrust or it is safe to slow down in thinner air. Then head back to the KSC. Half of this challenge is simply making it back to KSC and landing safely as is aptly pointed out in Sevant's crash videos.

My suggestion is to keep enforcing the hard ceiling as it has been so far.

[m1sz]

I was not planning on doing that, and is not stated in the rules!, but I see your point, slowing down is hard fighting your way in this thick air!

Anyway, about the speed record under 1.000m, I'm not so sure about forbidding going over 1.000m, it makes easier the comeback, but the thing is all about going as fast as possible under 1.000m with something able to land horizontaly.

What do the other contestants and public think?

[Visari]

I too believe the 1km limit should be abided at all times, even after max speed.

Also, to further the competition, I've been doing some more testing..

I think proper use of pfairings will determine the winner here.

I've found pwings can be highly abused, as previously demonstrated by my illegit craft.

It would be up to m1sz to ban these 'exploits' or allow them to be used.

As it is, shrouding the front of a tank + engine to reduce the frontal drag on the tank, doesn't seem to require the interstage adapter to be as large as the fuel tank, you could probably make it as small as you wish.

In addition, you require only one fairing, not 4, to remove frontal drag from the interstage adapter, the part directly behind the interstage adapter and everything inbetween the fairing and the interstage adapter.

this would reduce overall drag.

[snip]

YJ-91 operates at > mach 4.5 at just 20 meters above sea level.

[snip]

another issue is engines, which probably do not have the thrust capable of pushing an actual plane to > mach 4.5 below 1000 meters in KSP

Indeed, we'd require ramjets to go anywhere beyond mach 4.2 I think.

I noticed the turbojets with afterburner seem to die at about 1350+ m/s.

Anyway, I've been toying around trying to beat the record, but my install is starting to get unstable with bugs everywhere, especially b9.

I'm gonna keep myself in the background, theorycrafting while you speed devils murder the air

Edited February 7, 2014 by Visari

[m1sz]

do you mean procedural fairings?, I dont see the problem with procedural wings!

The fairings..., I'm taking that intoo consideration, and is shown in the leaderboard.

The spirit of this challenge is about creating a fast plane, any kind of exploit that looks ridiculous shouldnt be allowed.., but we alrdy allowed some planes with air intakes behind the fairings, so I think that we could do another leaderboard for those planes that uses fairings, will that be ok to everyone?

ill set the rule to be under 1.000m at all times, and ill update leaderboard now

[Sevant]

Indeed, we'd require ramjets to go anywhere beyond mach 4.2 I think.

I agree, but I don't just want ramjets (they stop helping at about mach 6), I want scramjets too so we can shoot for mach 24

...of course that would mean leaving orbit in a matter of seconds once you got up to speed--or rather before you got up to speed.

[palker]

Now we just need a real aerospace engineer to build something that goes 1500 m/s...Although we're not doing too bad. Today alone we improved the top speed from 1,090 m/s to 1,205 m/s. Considering that I thought I was reaching the limit of what could be done when I hit 928 m/s, I think progress is still racing along pretty quick.

Things may pick up pace with the next patch too. Supposedly, they are working on improving connection points to allow for building more rigid aircraft/rockets. That could make large planes with a ton of engines stable enough to fly at the speeds needed for this challenge.

I do not think that real aerospace engineer would hide intakes inside fairings

[Sevant]

I do not think that real aerospace engineer would hide intakes inside fairings

I don't think that's necessary for reaching mach 4.5...that said, more powerful engines or stronger joints may be necessary. That, or some uncommon genius.

[TheHengeProphet]

I don't think that's necessary for reaching mach 4.5...that said, more powerful engines or stronger joints may be necessary. That, or some uncommon genius.

While I have been actively monitoring drag on all of my parts, I have made an observation that while the intakes have remarkable drag--so far as FAR goes--having them covered has made no noticable impact on my speed. I'm still trying to determine the appropriate craft shape that can net me Mach 2, while still looking like a reasonable plane. Eventually, I'll try to run the numbers on thrust efficiency at these altitudes, because the given engines seem to make a remarkable difference in performance (so far the F119s seem to be the best).

[palker]

So i decided to build really small aircraft for this using the TV PP small engines and fuselage parts. The first iteration weighted around 800 kg and it was so small that it had to be launched from the clamp as it was barely larger than the smallest landing gear bay.

Current craft shown on the video weights 1549 kg. It contains two 0.625 fuel tanks two 0,625 structural fuselage sections 3 small turbojets one radial engine mount with air intake smallest probe core procedural fuselage shrouds to make up for the lack of decent 0,625 m nose cones. Wings are procedural as well as the all moving horizontal tailplanes. Vertical stabilizers use control surface and small wingtip from TV PP.

This thing is absolute ***** to fly it is extremely twitchy at high speeds mainly in roll the tiniest input and you are flying inverted and i cannot do anything about it without compromising elevator authority(well separate control surfaces for everything would help but also would cause more drag).

Another thing is that the thin high aspect ratio high sweep wing has murderous stall characteristics as you can see in in the video at about 3 minute mark crossing the critical AOA is death so you have to be really gentle with the controls and that also means very high turn radius.

Another side effect of that is that low speed flight is very difficult so landing is nearly impossible even though the aircraft is mostly landing gear when you look at it. Touch down speed is over 100 m/s and that combined with how the KSP landing gear behaves at high speeds especially on aircraft with narrow landing gear causes wobble that most of the time ruins the aircraft. The last segment of the video shows this. I tried drogue shoots, different landing gears but the results are always same - explosions. Few times i managed to bring the aircraft to full stop but never it was standing on the 3 wheels and always there was at least one bit missing. So technically it is possible to land it but you have to be really lucky. It is also quite difficult to actually slow down to that speed because drag of that thing is so low and TWR is about 11.

Again most of this could be sorted out with bigger wings and some flaps but that would get in the way of speed.

[TheHengeProphet]

So i decided to build really small aircraft for this using the TV PP small engines and fuselage parts. The first iteration weighted around 800 kg and it was so small that it had to be launched from the clamp as it was barely larger than the smallest landing gear bay.[snip]

This leads me to wonder if anything has been done (for anyone using FAR) to fix the poor entry in his code that causes the stock engines to have a peak velocity of 41800 m/s? Not saying yours isn't legit... I'm just saying that it's an issue that should probably be addressed for FAR users.

If there is any question to why I ask this:

Javascript is disabled. View full album

Edited February 8, 2014 by TheHengeProphet

[Sevant]

So i decided to build really small aircraft for this using the TV PP small engines and fuselage parts.

Are those small engines in a separate mod or have I just never noticed them in B9?

I liked your plane, though I have a few suggestions for making it easier to land.

1) Reduce the amount of fuel you have on take-off. You should only need about 20 fuel units to fly the mission, and your craft will be easier to land when it's empty of fuel weight.

2) Try putting your rear landing gear on your wings. It will let the plane sit lower to the ground and give you a wider wheel base. (As a bonus, it will pitch the plane up on takeoff such that it will take off by itself without pitch input.)

3) Try not to touch down until you're going less than 100 m/s...might not be possible if your plane stalls above that speed.

4) Watch my videos to see how not to land, then seriously question taking any advice from me

[palker]

This leads me to wonder if anything has been done (for anyone using FAR) to fix the poor entry in his code that causes the stock engines to have a peak velocity of 41800 m/s? Not saying yours isn't legit... I'm just saying that it's an issue that should probably be addressed for FAR users.

If there is any question to why I ask this: http://imgur.com/a/7phCZ

The small parts are Taverios Pizza and Aerospace http://forum.kerbalspaceprogram.com/threads/15348-0-22-x-Taverio-s-Pizza-and-Aerospace-v1-5-1 (TV PP for short) and incidentally the same mod fixes the bug in FAR that causes engines to not to lose thrust at high speeds because it modifies the engines as well. Thrust cuts of at about 1100 and to go faster you would need ramjets.

[m1sz]

I've never used Taverios, so I'm not familiar with what it does to the physics.

If it fixes that bug, will it cause planes to go slower?, or it's all about higher mach speeds in upper atmosphere

[m1sz]

This leads me to wonder if anything has been done (for anyone using FAR) to fix the poor entry in his code that causes the stock engines to have a peak velocity of 41800 m/s? Not saying yours isn't legit... I'm just saying that it's an issue that should probably be addressed for FAR users.

If there is any question to why I ask this: http://imgur.com/a/7phCZ

I guess everyone is using stock FAR, no modifications

[palker]

So i tried a redesign unfortunately the plane is still quite impossible to land. I will try to make something that can land later today. Hopefully it will stay above Mach 2 at least.

[Hejnfelt]

1,402 m/s - MACH 4.134 - B9 and Procedural fairings with FAR

Equivalent of 5,047 km/h or 3,136 mph

Well... First the proof:

Top speed @ 1:05

Landing @ 10:30

Now for some comments.

Flying the craft

You may find it odd that I chose to fly the aircraft from the angle shown in the video. This is however fully conscious as flying it from a chase perspective gave me very little visual input regarding the position of the plane - i.e. the direction of thrust - in relation to its prograde vector. This is crucial since deviating outside or even close to the edges of the prograde vector on the nav-ball at >mach 3 speeds, will end in catastrophic failure. Observing the plane from a backwards facing fisheye perspective allowed me to use the conic fairings as a very precise indicator of the planes positional direction in relation to the prograde vector in combination with the navball.

Craft design

Initial design credit goes to user Sevant. This craft design is very suited for fast flights.

Engines

More engines means more thrust. But it also requires more air. I tried several designs featuring 2 radial intakes on the sides of the craft, but they generated so much drag that achieving +1200 m/s was a challenge. The centered radial intake in the front took many tries to perfect. Just a few steps up or down in the SPH and the intake would generate drag either pulling the plane towards the ground or towards the sky, making it impossible to fly above 500 m/s.

There has been talk about engines in this thread and the fact is that the stock TurboJet is the best for > 1000 m/s flight. The B9 engines all cut out between 1100 - 1430 m/s meaning at 1000 m/s they are at 1 thrust multiplier and at 1430 they are at 0. The stock Turbojets however 0 out at 2400 m/s and achieve multiplier 1 at 1000 m/s. This means that when the B9 engines cut out, the TurboJet still enjoys around 75% of its thrust capacity.

If you wanna go fast you must use the stock TurboJet. Anyone who wants to know more should check out the followign imgur album by user Tarvert.

http://imgur.com/a/hyuPE#0

Tarvert is a source of amazing information and if you like looking at graphs like the one for the atmospheric engines, you will enjoy some of his other work submitted to Reddit:

http://www.reddit.com/r/KerbalSpaceProgram/search?q=tavert&restrict_sr=on

Stability

Stability is another issue. As explained in my flight note, simply deviating outside the green prograde vector on the navball at speed will end in complete disintegration due to drag forces applied to the craft parts. Some parts even explode due to the impact with the air. My design features control surfaces for the purpose of stabilizing the craft at speed. These also help move the center of lift back slightly which helps tremendously in landing the craft and flying it at slower speeds. Stability is even more of an issue on the return flight as this design is very rear heavy. This is also why I drop the engines - or at least tried to with the reduced weight, it is easier to fly and land.

You may think putting rudder(s) on your craft will achieve stability and you'd be right, but it puts unnecessary drag on your craft and your top speed will likely be < 1300 m/s.

Craft shape

I have tried long thin and circular designs and none of them match up to the wide and flat design initially shown by Sevant. I have also experimented with different fairing shapes and while the length of the procedural fairings do not seem to matter for speed, the longer fairings can help move the center of mass forward. The conic fairings work best for visual clues about the direction angle of the plane when looking back on it during flight.

Landing

You want to switch off braking on your front landing gear. If you find yourself landing at 100 m/s, braking on the front wheel can - more like will - be catastrophic.

Also make sure your rear landing gear is somewhat spread out. With a think shaped plane you'll want to place your landing gear farther out on the tip of the delta wings than I have. Due to the wide footprint of my craft I put them closer to the body of the craft to decrease drag in flight and decrease flex upon landing or the belly of the craft may have impacted the ground.

Conclusion and suggestions for other competitors

Use TurboJets. Consider fuel necessary. Make sure you have some control surfaces for stability at max speed. Use the COM and COL indicators in the SPH during construction. Be extra careful during slowdown or this happens

Failure @ 1:10

Edited February 8, 2014 by Hejnfelt

[m1sz]

1,402 m/s - MACH 4.134 - B9 and Procedural fairings with FAR

Equivalent of 5,047 km/h or 3,136 mph

Well... First the proof:

Top speed @ 1:05

Landing @ 10:30

AWESOME new record!!!, im so glad you two are making so many entries, the improvement is so good!, I wonder if we will find another magic shape that will allow us to go even faster!

Im gonna do some tries this weekend!, so I can upload my entry to keep it always under 1.000m

[Hejnfelt]

AWESOME new record!!!, im so glad you two are making so many entries, the improvement is so good!, I wonder if we will find another magic shape that will allow us to go even faster!

Well it's a great challenge and anyone trying it will definitely learn something about aircraft design.

I know for a fact, faster is possible. The Turbojet's velocity curve looks like this

The thrust multiplier decreases very slowly in a non-linear fashion from max 1.0X at around 1000 m/s to ca. 0.5X at 2000 m/s. Meaning at 1400 m/s I was still enjoying around 80% of max thrust and definitely had not hit the limit on thrust needed to overcome drag.

With weight optimization (fuel mostly) one can go even faster.

But most importantly! I didn't make full use of my air on this design. Theoretically the radial intake should keep even more TurboJets running so perhaps someone will come up with an even better design. But then... You also have to fly it. And that's easier said than done

Edited February 8, 2014 by Hejnfelt

[Hejnfelt]

I don't think that's necessary for reaching mach 4.5...that said, more powerful engines or stronger joints may be necessary. That, or some uncommon genius.

It's not and yes the joints are becoming an increasing problem. So is impact force with the air if you can't keep your prograde vector and aircraft nose direction aligned.

While I have been actively monitoring drag on all of my parts, I have made an observation that while the intakes have remarkable drag--so far as FAR goes--having them covered has made no noticable impact on my speed. I'm still trying to determine the appropriate craft shape that can net me Mach 2, while still looking like a reasonable plane. Eventually, I'll try to run the numbers on thrust efficiency at these altitudes, because the given engines seem to make a remarkable difference in performance (so far the F119s seem to be the best).

The F119 is most efficient and seems good, but the TurboJet is king above 1000 m/s. The F119 won't even reach 1200 m/s as it cuts off before then.

that causes the stock engines to have a peak velocity of 41800 m/s? Not saying yours isn't legit... I'm just saying that it's an issue that should probably be addressed for FAR users.

41800 m/s seems really really fast. Like >mach 100 fast. I experience thrust velocity curves that follow the cfg files to the letter.