Jet Engine Speed Challenge.

[LocoCatpwnz]

can we use VTOLs?

[Haldane]

New craft, new top speed:

924m/s

[khyron42]

It\'s all about thrust AND drag. with lots of engines but very few fuel tanks I was getting better results. It just took creative arrangements that allowed all engines to power off of a single fuel tank for the final sprint.

I\'m amused by the mechjeb everywhere in these screenshots too, but it does save a lot on weight to not have an ASAS - I might have to retry this challenge again in a minute.

[Excalibur]

Record title: World Airspeed Record

Record statistic: 967.4m/s

Game version when record achieved: 0.15.2

Screenshots:

Mods used:

Tiberdyne Big Shuttle Wing

MechJeb

Craft name: Meteor Mk II

[khyron42]

Excalibur - Nice example of simpler is better.

For the other direction: The Flying Engine II. Switched to MechJeb since everyone else was moving to it instead of stock, and mk 2 fuselages for slight mass savings in the early part.

Liftoff...

Right before burn out...

Final Results after burnout:

Record title: World Airspeed Record

Record statistic: 989m/s

Game version when record achieved: 0.15.2

Mods used:

MechJeb

Craft name: Flying Engine II

[Excalibur]

Nice work mate! Lots of engines but fundamentally simple - I like it! Did that take a lot of testing? Usually takes me three flights or so to optimise a design, unless I strike it lucky I guess.

Now to see if I can crack 1km/s...

[khyron42]

I tried about 4 designs to get higher speeds, but all of them managed to get airborne and into the 900+ speed range. - based on past attempts I was pretty sure it would work. The main concern was whether having that much of the thrust coming from in front of the CoG would destabilize it, but it worked quite well.

I think with that number of engines wing lift may not matter; I should try it with 2-4 more engines and just canards on the sides. We\'re both trying for 1 km/s!

[Excalibur]

I tried about 4 designs to get higher speeds, but all of them managed to get airborne and into the 900+ speed range. - based on past attempts I was pretty sure it would work. The main concern was whether having that much of the thrust coming from in front of the CoG would destabilize it, but it worked quite well.

I think with that number of engines wing lift may not matter; I should try it with 2-4 more engines and just canards on the sides. We\'re both trying for 1 km/s!

I\'d have thought that thrust in front of CoG would make it more stable if anything else. Great design though, I never even thought of using the Mk2 fuselages for some reason. Like the name too, a lot of my previous designs could be described as such!

I think MechJeb is an essential tool in this application - just set the SURF heading/pitch to what you want and you get a nice smooth profile. The only mods I\'ve used for this challenge are structural and aerodynamic - I still think the stock options are a bit limited in that department. I always use the stock tanks and engines though otherwise it seems a bit pointless - I\'m sure I could edit the Turbojet .cfg and get silly speeds but that\'s not the point is it?

Anyway I hate to break it to you buddy but I just passed 1000m/s.

Got up to about 1005m/s but we\'ll go with the picture at 1002.3m/s.

Your move Sir Kyhron...

[Salda007]

Just throwing my hat into the ring, here.

2nd attempt, stock parts only, 946 m/s level flight. Can probably push it faster, but it\'s a very, very fickle craft. More info and attempts when I\'m not on my lunch break. 8)

[khyron42]

If you can post the 'F3' results from after burnout I\'d give you credit for 1005, which means I\'m in second place but still broke the 1 km/s level... the largest mess I managed to build that could actually survive takeoff only reached 1002.7.

[shhhilent1]

If you can post the 'F3' results from after burnout I\'d give you credit for 1005, which means I\'m in second place but still broke the 1 km/s level... the largest mess I managed to build that could actually survive takeoff only reached 1002.7.

Oh.

My.

GOD!

[Joshmo]

Madre de Dios.

[Phoenix Aerospace]

Wat. How can that even fly?

[Excalibur]

If you can post the 'F3' results from after burnout I\'d give you credit for 1005, which means I\'m in second place but still broke the 1 km/s level... the largest mess I managed to build that could actually survive takeoff only reached 1002.7.

That thing is absolutely beautiful! I love the first picture, that\'s an awesome piece of kit. No I never thought to take the \'F3\' shot so 1st place is actually all yours... for the time being...

You might be able to get a bit more out of that anyway... The first two flights with my craft were around 980-990m/s. I found the most efficient flight profile was to climb at 45 degrees and 1/3 throttle until I hit about 13km. Then gradually reduced the pitch to about 8 degrees whilst slowly advancing to 100% throttle position. That got me just above 1k. What profile did you use?

Wat. How can that even fly?

My guess is that it has so many engines it doesn\'t need many wings. I imagine the vectored thrust gives a strong lift vector.

[khyron42]

It also sits on the runway already angled upwards slightly, so the 'wheel drag' doesn\'t prevent it from getting the initial lift needed to get airborne.

I\'m going to try it again with less canards, later on.

----

My flight profile is 100% throttle the whole way, takeoff at 20 degrees up pitch, pitch down to 10 at 13 km, and then try to manage the pitch to level flight above 16.5 km. it seems that as long as you end your sprint in a sustained level flight, you\'ll get the same results no matter how you got there; you just have to be in level flight long enough for all acceleration and drag factors to have reached equilibrium. I reach 16km with 1/2 the fuel left anyway, and gain my last 200 or so m/s while levelling off.

I think the biggest thing holding mine back right now is altitude-related air drag; I just had a successful flight with only one set of canards and one more pair of engines, making this technically a jet-propelled projectile rather than an airfoil. However, I ended at a lower speed because my 'level flight' ended up at a 200m lower altitude. Time for work, but tonight I\'ll start trying for the 17-18km mark instead.

[Salda007]

I think the biggest thing holding mine back right now is altitude-related air drag; I just had a successful flight with only one set of canards and one more pair of engines, making this technically a jet-propelled projectile rather than an airfoil. However, I ended at a lower speed because my 'level flight' ended up at a 200m lower altitude. Time for work, but tonight I\'ll start trying for the 17-18km mark instead.

Sweet mother of chrome! That thing\'s absurd! I approve!

My little jet-bullet has really highlighted the factor that atmospheric drag plays. 15.7km = 945 m/s, 14.9km = ~875 m/s or so. On the other hand, drifting above the 17 km mark or so causes the engines to lose too much power, and you lose speed that way. The trick is keeping it in the sweet spot for long enough...

[Phoenix Aerospace]

Inb4 someone gets orbit. It\'s possible to get a >900 km apoapsis just by using one of the horrendously overpowered spider-tech scramjets.

[Excalibur]

It also sits on the runway already angled upwards slightly, so the 'wheel drag' doesn\'t prevent it from getting the initial lift needed to get airborne.

I\'m going to try it again with less canards, later on.

----

My flight profile is 100% throttle the whole way, takeoff at 20 degrees up pitch, pitch down to 10 at 13 km, and then try to manage the pitch to level flight above 16.5 km. it seems that as long as you end your sprint in a sustained level flight, you\'ll get the same results no matter how you got there; you just have to be in level flight long enough for all acceleration and drag factors to have reached equilibrium. I reach 16km with 1/2 the fuel left anyway, and gain my last 200 or so m/s while levelling off.

I think the biggest thing holding mine back right now is altitude-related air drag; I just had a successful flight with only one set of canards and one more pair of engines, making this technically a jet-propelled projectile rather than an airfoil. However, I ended at a lower speed because my 'level flight' ended up at a 200m lower altitude. Time for work, but tonight I\'ll start trying for the 17-18km mark instead.

My last craft sits on the runway pointing upward at about a 40 degree angle. Have to use full power on take-off as otherwise the engines overheat from friction with the runway and explode.

I did use your kind of flight profile in the past but I did find it slightly more fuel efficient to do a low-throttle steep ascent to altitude, then pitch down a little at a time and throttle up. Almost like a gravity turn when I think about it. Hard to describe though as I\'m not too precise about timings/altitudes for changing throttle and pitch. I generally just do it when it \'feels\' right.

Different craft may suit different profiles however I suppose.

[Phoenix Aerospace]

Not content with simply being the resident representative of the peanut gallery, I gave it a whirl. I give you my Squirrel Mk.1, with a final speed of 921 m/s at an altitude of ~17.5 km. Also, I\'m not really feeling the loss of power. It may just be that I\'m a total newb at this.

Edit: Tried again with seven engines instead of four. Got about 969 m/s out of it.

[khyron42]

Surely someone can break the 1010 m/s barrier? I\'ve tried a few times to improve on my 1002.7 speed but I\'m starting to think I did everything exactly right on that flight - I\'ve broken 1000 a couple more times but only gotten up to 1001.

Attempts with even more engines haven\'t gotten better results either, but my attempt at a 60-engine monster did rip itself to shreds entertainingly.

[Phoenix Aerospace]

Got booted off the PC, so probably not. Well, at least in my case. Anyhow, I think that by honing my skills, I should be able to break 670. Also, I found that sweet spot you were talking about. In spoilers to avoid ruining the fun of experimentation (goodness, that sounded weird ).

~17500 km.

[Salda007]

Hmm, most of my fastest runs have been lower down, around 15.7 km or so. That high up, my engines tend to choke and lose too much power. I hit 957 m/s in a shallow dive the other day (~936 m/s overland speed); probably could\'ve pushed it faster as I dropped back down into thicker air before finally running out of fuel at about 14.5 km.

Of course, since I\'m basically flying air-breathing rockets (wings? pfah! Who needs \'em!), my altitude tends to be not entirely stable, which I\'m sure is costing me some top-end speed. I need to find a low-drag wing configuration that allows for steady, level flight without tumbling aft-over-teakettle.

BTW, those of you cracking the 1 km/s barrier, are you flying stock, or modded?

[Excalibur]

BTW, those of you cracking the 1 km/s barrier, are you flying stock, or modded?

I\'m using stock tanks and engines, but use modded wings (Tiberion\'s Shuttle Wing Small) since they provide much more lift than the stock parts. I have managed to crack 1km/s with stock only though, however my fastest craft uses the modded wings.

Here are some examples of my latest designs:

Kkyron, I think 1010m/s will be VERY hard to attain with stock engines and tanks.

[Salda007]

Not to be a hard case, but given how important altitude management is to this challenge, I don\'t consider flying with Smart A.S.S. to be stock.

[Excalibur]

Not to be a hard case, but given how important altitude management is to this challenge, I don\'t consider flying with Smart A.S.S. to be stock.

I can see why you may think that, especially if you\'re coming from a hardcore-stock-parts-only viewpoint. In my defence I see this challenge more as a test of design acumen rather than piloting skill, so I think the use of MechJeb is fair in this context. It\'s a good way to ensure consistent results with a design and to also test a design to its limits.

If the challenge were to fly straight and level at 100m for 10km then I\'d say fair enough!