RAPIERs and Turbojets are amazing in 1.0.3

[Falkenherz]

Well, to just turn down the steam a bit, my second-frequently used spaceplane still runs fine. It seems that all we have to do is add more trust, to compensate for the new early, low-altitude weakness. OFC some designs might find it difficult to have more engines added, mine thankfully still have some space on the wings for another nacelle. Ah, yes, the Mk1 fuel tank needs to be removed and re-added in order to update to the new fuel amount.

I would nevertheless be grateful if Squad could drop a hint whether they are now fine with the atmospheric model or still tinkering about. My career save is very much behind with its projects because I like to fly planes and spent a lot of time on designing and trying them instead of just pushing that timewarp button for your next upcoming transfer window or SOI change.

Edited June 25, 2015 by Falkenherz

[Old Foxboy]

add more trust

mmd

[herbal space program]

FWIW, after claiming haughtily that the new aero nerfs rather than improves SSTO performance, I was humiliatingly shown a 1.0.4 SSTO plane with a higher payload fraction on LKO than anything I was able to make in 1.0.2. Going back to the drawing board, I found that hugging the ground for the first 20 seconds of so after takeoff and before pulling up made all of the difference. In 1.0.2, my takeoff speed was such that I could just pull up to 30 deg right off the runway and motor into the sky with 4 RAPIERS pushing 47t. Now that's just a no-go, and what would really work best is another km or two of runway to gain speed on the ground with those wimpy engines, but grazing the water for half a minute before pulling up seems to do the trick well enough. You just want to get your speed north of 200m/sec before particularly pointing your ship towards space. You also want to do your flaming hyper-thrust transonic acceleration lower down than before, at maybe 17km instead of 19.With those two changes and some moar wings I was also able to get to a better deltaV on LKO than I could in 1.0.2.

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I haven't tried it yet, but does it help to add some engines? It feels like it's needed, as my profile were mostly running of air before reaching what felt the RAPIER top speed. But maybe the extra weight is too much to help...

Moar wings and less climbing right after takeoff is what you need.

[Wjolcz]

Two RAPIERs and a bunch of wing parts seems to be just enough to reach space.

[eddiew]

Two RAPIERs and a bunch of wing parts seems to be just enough to reach space.

Interestingly minimal - what sort of cargo can you shift with that?

[Wjolcz]

Interestingly minimal - what sort of cargo can you shift with that?

Haven't determined that yet. Flew it only twice to orbit and back to test basic things and apply few tweaks here and there.

E: Here's a thread (and shameless self promotion) for anyone who is eager to try fitting as much payload as it's possible in the thing: http://forum.kerbalspaceprogram.com/threads/126716-The-Superbird-MKII

Edited June 26, 2015 by Veeltch

[selfish_meme]

A single Rapier and some very small wings was enough to SSTO in 1.02-3, have not tried in 1.04 but I expect it to work. This is my Jool GT Lander, and overly complex Kerbal deposit infrastructure.

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Yes, I know about Take Command, now

[Captain H@dock]

Moar wings and less climbing right after takeoff is what you need.

I was refering to the last moment of the hypersonic on air-breathing.

From something like 1100 (and accelerating) at 9K-11K, I am either:

A. Climb at 20-25 degrees, but peaking around 1400 at 25K.

B. Climb at 10-15 degrees, thus peaking around 1475 at 25K.

A is not maxing what I could get from air-breathing, but B is quite shallow a climb, which means quite a lot of time in draggy territory (25K-35K) on rocket mode. I feel I could benefit from getting the B scenario speed with a A angle of climb. And that would only be possible by increasing TWR, hence my question...

[Red Iron Crown]

Things have definitely improved, even with the nerfed Isp. In 1.0.2 I struggled to get a nuclear plane to orbit with 4km/s of dV remaining, in 1.0.4 my first attempt got over 5km/s with a design that wasn't even optimized much and had a fairly sloppy ascent. More wing and fewer Rapiers plus better mass ratios in Mk1 fuselages add up:

[eddiew]

http://i.imgur.com/SkGpFfp.jpg

Quoting myself to re-link this image

This plane works under both 1.0.4 stock, and FAR, which is interesting. More interesting still is that FAR gives it barely 10% more delta-v in LKO, but makes it a lot harder to land due to doubling the take-off speed.

Anyone else been running any comparisons with nu-nuStock aero vs nuFAR? Much as I respect FAR (and played with it for a good 4 months), it doesn't half slow my career down due to the long and iterative design process required. If the changes to 1.0.4 stock are consistently this compelling, I might have to take the easy option this time round ¬_¬

[herbal space program]

I was refering to the last moment of the hypersonic on air-breathing.

From something like 1100 (and accelerating) at 9K-11K, I am either:

A. Climb at 20-25 degrees, but peaking around 1400 at 25K.

B. Climb at 10-15 degrees, thus peaking around 1475 at 25K.

A is not maxing what I could get from air-breathing, but B is quite shallow a climb, which means quite a lot of time in draggy territory (25K-35K) on rocket mode. I feel I could benefit from getting the B scenario speed with a A angle of climb. And that would only be possible by increasing TWR, hence my question...

Sorry for the misunderstanding. I replied as I did because the actual TWR bottleneck in 1.0.3 is at the bottom of your flight profile not the top, so you definitely don't need more engines at the top vs. 1.0.2. Based on what you said, I'd say what you need is more intakes and not more engines, because 25km is too low to be switching over. My best current plane is 50.2t runway weight with 4 RAPIERs (i.e. 12.5t/engine) and a nuke. I think based on what RIC posted I could actually go somewhat higher, to maybe 15t/engine. The best ascent profile I have been able to come up with for that goes something like this: Hug the ground after takeoff for 15-20 seconds, building speed to >200 m/s, then pull the nose up to ~25-30 degrees, for a low atmosphere climb rate of ~80-100m/s. I maintain this attitude until ~12km, then pitch down to 5-10 degrees to go transonic. Once my speed gets to >425m/s, I pitch back up to maybe 20 degrees, until I get back to a climb rate around 100m/s, usually around 14-15km. I then put my nose right in the middle of the prograde marker and burn until I hit my maximum air-breathing speed, around 1450-1460 m/s at around 21km. I then pitch up to around 20 degrees again, letting my velocity drift down to around 1400 m/s at 25km. At that point I engage my nuke engine for a little extra thrust. Holding in that attitude I can typically get to 29-30km on air, with right around 1300m/s velocity and maybe 175m/s of climb at switchover. I then burn rockets at 20-35 degrees pitch until I get to maybe 33km, then nose back down to 5-10 degrees and try to get to >1900 m/s before cutting the RAPIERs. If I do everything right, that gets me to an apoapsis of around 60km, which I try to circularize with the nuke such that my apopapsis reaches 70km just before my periapsis does. If I convert the oxidizer I schlep to orbit into fuel, a good ascent following that profile would theoretically get my ship on orbit with around 4500dV remaining. RIC just recently managed 5000, so clearly there is still room for improvement from that.

[Brotoro]

Things have definitely improved, even with the nerfed Isp. In 1.0.2 I struggled to get a nuclear plane to orbit with 4km/s of dV remaining, in 1.0.4 my first attempt got over 5km/s with a design that wasn't even optimized much and had a fairly sloppy ascent. More wing and fewer Rapiers plus better mass ratios in Mk1 fuselages add up:

https://dl.dropboxusercontent.com/u/61004449/KSP/1.0.4/screenshot280.png

Why do you RAPIERs have cones on them?

[Fenris]

Why do you RAPIERs have cones on them?

Coolness factor +1. My guess anyway.

[Red Iron Crown]

Why do you RAPIERs have cones on them?

Drag reduction. It's a Rapierspike, as shown here on the forums by Levelord; adding a small nosecone or a shock cone intake (as shown) to the back of a Rapier greatly reduces drag compared to the Rapier alone. Doesn't interfere with the thrust or overheat.

[herbal space program]

Drag reduction. It's a Rapierspike, as shown here on the forums by Levelord; adding a small nosecone or a shock cone intake (as shown) to the back of a Rapier greatly reduces drag compared to the Rapier alone. Doesn't interfere with the thrust or overheat.

Hmm..... Smells a bit of trickery to me, but I guess I'll have to try it now!

Edited June 26, 2015 by herbal space program

[selfish_meme]

My best current plane is 50.2t runway weight with 4 RAPIERs (i.e. 12.5t/engine) and a nuke. I think based on what RIC posted I could actually go somewhat higher, to maybe 15t/engine.

My Payload Fraction challenge entry from last night (which is no record breaker) is at about 16.5t per Rapier.

[Yakuzi]

Nao designed a craft with a single rapier bringing 18.27 t to orbit with a payload fraction >50%.

I've been testing a bit but noticed mixed results depending on length and type of inline parts while keeping mass and engine layouts the same. I'll post the results after some more thorough testing and analysis (and time/motivation).

Edited June 27, 2015 by Yakuzi

[Brotoro]

I was playing a lot with RAPIERs today... and I can't say I noticed anything amazing about them. The yet-again lowered thrust is annoying. Is there some magical realm of altitude and velocity where they display their wonderfulness?

[eddiew]

I was playing a lot with RAPIERs today... and I can't say I noticed anything amazing about them. The yet-again lowered thrust is annoying. Is there some magical realm of altitude and velocity where they display their wonderfulness?

Well, yes, that's what thrust curves are about Rapiers only really deliver their good performance upwards of mach 2. They'll handle at least 16t per engine, with a streamlined build.

If you're struggling with rapier-only builds in 1.0.4, my suspicion is you're climbing too fast. Suggested flightplan:

- leave the runway at 5 degrees and stay low until 250m/s or better.

- ascend to 10-12km carefully. Sharp stick movements make drag, don't pull up so hard that you slow down.

- lower the nose gently until you reach level flight and/or pass 400m/s*. Rapiers will now be delivering nearly double your runway TWR.

- ascend carefully again, making sure you don't lose speed.

- watch your AP and plan ahead so's to completely level off at 20km. That usually means lowering the nose around 17-18.

- rise super-slowly through 20-22km. You'll probably enter this band about 700-800m/s - you can leave it at over 1400. This is the magic realm

- keep an eye on your AP as the TWR drops off, and avoid switching to rocket mode until your time to AP is reducing. Odds on it'll be upwards of 28km by this point.

- if you pull up, again, do so gently. By this point you'll be fast enough that the curve of Kerbin is taking you to space, so it's not mandatory.

* if you can't break mach 1 in level flight at 12km, you've built a drag-monster and need to review it and/or ask for advice

[herbal space program]

Well, based on all that, It seems like I must have a drag monster on my hands. I'm at 14.75t/RAPIER, and while the high end looks fine, breaking Mach 1 has gets too time-consuming if I go above that ratio. Adding the shock cones to the backs of the engines did make a pretty noticeable difference though. Before I did that I couldn't manage more than 12.5t/RAPIER. Now I'm getting on orbit with 30.76% of takeoff weight in fuel, for about 4700 dV, 5100 theoretically if I convert my oxidizer to LF. I'm getting a total PF on orbit of 34%, which is not bad based on RIC's PF challenge thread but can clearly be improved upon.

http://imgur.com/d7qFRLo

Edited June 27, 2015 by herbal space program

[Red Iron Crown]

herbal, I bet it's those bicouplers. One of the Mk2 adapters and the Mk2 bicoupler would be less draggy, I think.

[waterlubber]

Yeah, the bicouplers are drag monstrosities. Occlusion may be broken on them. I would make the outriggers Mk2 instead.

[herbal space program]

herbal, I bet it's those bicouplers. One of the Mk2 adapters and the Mk2 bicoupler would be less draggy, I think.

Thanks, I'll give that a try. It would also generate some lift where I need it, so I could drop some wing area.

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Yeah, the bicouplers are drag monstrosities. Occlusion may be broken on them. I would make the outriggers Mk2 instead.

Thanks for the tip. I think that what RIC suggested would be better than just making the whole outriggers MK2, because those MK1 fuselages now have a really good ratio of mass/drag. Perhaps I'll try it both ways...

[GoSlash27]

Holy schnikeys!

I just dabbled in 1.04 for the first time tonight, and the RAPIER is hitting nearly 1500 m/sec on open cycle!

This is going to make SSTO spaceplanes a fair amount easier than 1.02, even with the Isp nerf.

Best,

-Slashy

Edited June 28, 2015 by GoSlash27

[LittleBlueGaming]

I made an SSTO spaceplane that can actually carry cargo! Up until now they have only been crew transport.

10t cargo, 35t at launch.

I'm sure it's a mixture of me getting better, and the new changes.