Space Plane Assent

[Slam_Jones]

Some more great information thanks people.

My desire to try using Whiplash engines for the initial climb seems fruitless, unless I "cheat" and dump them at around 10km, with plenty of speed for the Rapier engines.

I solved the problem of having the CoM so far back, gear attachment became an issue, by simply switching to the inline cockpit (doh!)

One problem I sometimes have - deorbiting with little fuel and electricity, the plane can flip then go into a flat spin which is a real challenge to get out of. Is this a result of pilot error or having the CoM to near the centre of the vehicle?

At the moment, my space planes are only "recoverable" with a large clean up team with brooms!

That would be a result of your COM moving too far, causing instability. Think of an arrow: fins helping to stabilize the back, heavy tip at the front. Try moving your remaining fuel around just before re-entry. Try putting it all at the front for one attempt, then try putting it all at the back for another attempt. It should help you figure out where you want the weight on re-entry.

On the bright side: tumbling through the atmosphere slows you down a LOT quicker than going in flat. But you also usually die.

Edited August 27, 2015 by Slam_Jones

[Alshain]

I did get one to orbit, finally, but with barely enough fuel to get back at 75km. I switch out the Rapiers for TurboJet/Aerospike combo. I guess the Rapier is just dead weight now, ISP is far too low. This will be my last plane, It's just not fun anymore, the only cargo I was able to carry was a fuel tank full of fuel, to deliver the empty to space. Maybe I'll see if I can find an old copy of 0.90 with FAR.

[Red Iron Crown]

I think you're giving up too easily, Alshain. They can be made to work, and Rapiers actually yield better payload fractions than hybrids. The Isp nerf to Rapiers is somewhat insignificant, they've gone from incredibly awesome efficiency to just awesome efficiency.

But if they're not fun for you, I guess that trumps everything.

[Alshain]

I think you're giving up too easily, Alshain. They can be made to work, and Rapiers actually yield better payload fractions than hybrids. The Isp nerf to Rapiers is somewhat insignificant, they've gone from incredibly awesome efficiency to just awesome efficiency.

But if they're not fun for you, I guess that trumps everything.

Then why can't they get to orbit? It makes no sense, I can't get a 23 ton craft with 2 freaking rapiers to orbit. It's not like I'm some beginner at this, I've been making planes with FAR since 0.23.

[Slam_Jones]

Then why can't they get to orbit? It makes no sense, I can't get a 30 ton craft with 2 freaking rapiers to orbit. It's not like I'm some beginner at this, I've been making planes with FAR since 0.23.

The two biggest factors for me have been ascent profile and fuel ratio. Just getting one of them right doesn't seem to do it... I've done a nearly perfect ascent, just to realize I packed way too little oxidizer to complete orbit... and vice versa (not reaching orbit because it was too heavy due to excess fuel).

I've done two launches (same plane, same payload, same engines, same fuel) right after each other, and had orbital dv differences of nearly a hundred dv.

It's just a much finer line that it used to be, is what I guess I'm saying.

[Alshain]

The two biggest factors for me have been ascent profile and fuel ratio. Just getting one of them right doesn't seem to do it... I've done a nearly perfect ascent, just to realize I packed way too little oxidizer to complete orbit... and vice versa (not reaching orbit because it was too heavy due to excess fuel).

I've done two launches (same plane, same payload, same engines, same fuel) right after each other, and had orbital dv differences of nearly a hundred dv.

It's just a much finer line that it used to be, is what I guess I'm saying.

That assumes you only want a 75km orbit. It should not be that fine a line if you want to go any higher than that. It doesn't work. I want to do more then go to barely orbit. I want to rendezvous with a station at 300km, while carrying cargo or personell for it, but if the line is that fine, then it isn't possible. I'm sorry, they really ruined planes in this game. I'm done.

[Starhawk]

Then why can't they get to orbit? It makes no sense, I can't get a 23 ton craft with 2 freaking rapiers to orbit. It's not like I'm some beginner at this, I've been making planes with FAR since 0.23.

The thrust and drag curves make the ascent profile extremely sensitive to small changes. A few degrees difference at the wrong moment can mean not going to space vs. getting there with dv to spare.

The ascent profile used now bears no resemblance to that used in stock 0.90. I can't speak to FAR since I never used it.

I think piloting a spaceplane to orbit is much more interesting, challenging, and quicker now than it was pre-1.0.

The absolute key in my ascent profiles is to run hot and level during the optimum power band of the engine. I try to level out and get the vertical speed between 0 and 10 around 12 km altitude, activate SAS and let the vehicle slowly and naturally pitch up as the speed climbs. I try to get 1400 to 1600 m/s top speed before switching to rockets.

Happy landings!

[Slam_Jones]

That assumes you only want a 75km orbit. It should not be that fine a line if you want to go any higher than that. It doesn't work. I want to do more then go to barely orbit. I want to rendezvous with a station at 300km, while carrying cargo or personell for it, but if the line is that fine, then it isn't possible. I'm sorry, they really ruined planes in this game. I'm done.

I know the feeling, trust me. I had just started to get good at SSTO's in 0.90, and then 1.0 dropped, and nothing worked. I was actually pretty mad (well... more than pretty mad, honestly). I completely stopped playing for a few months even. I may have vowed to never make another SSTO again, to give you an idea of how I felt.

Gradually I got back into it, but it's been a slow climb. If it's too frustrating, I say take a few weeks off and let the dust settle a little. At least that's what I did Another thing I did was turn off re-entry heat, as it was a mechanic I just did not like, nor wanted anything to do with.

The SSTO I posted could make it to the station at the orbit you mentioned. I agree, though, that it's a lot more difficult than it really should be. I'd love to get my Mk3 line of station-building SSTO's going again, but I kinda feel like it might be impossible with my skill level. Maybe if I really fine-tuned them, but it seems it may be more trouble than it's worth. Pick your battles and all that jazz.

Good luck!

Edited August 27, 2015 by Slam_Jones

[GoSlash27]

Has anyone built a true SSTO spaceplane. I can't seem to find an ascent that works at all. I can build an SSTO jet assisted rocket with wings that looks like a plane, but does anyone have a plane with sea level TWR <1 that reaches orbit? Because, if not, there seems to be no point to spaceplanes in this game anymore, aside from shuttles. I just can't find a way and still have any fuel once I get to suborbital speeds.

There's a huge supply of SSTO spaceplanes with TWR <1. We've got them in the K prize thread and pro builder challenge. I'm sure there's loads of them on the craft exchange also.

The Mainway Adobe is a very low t/w SSTO with large payload fraction. Also low- tier tech.

It weighs 36 tonnes and is powered by 2 Whiplashes, 18t per engine. sea level t/w .72.

LTP II:

Something I arrived at helping someone else optimize their spaceplane.

126 tonnes, powered by 6 Whiplashes. 21t per engine, sea level t/w .62.

The easy way to do it is this:

Build a spaceplane with nothing but fuel and oxidizer. Optimize the ascent profile to get it to your desired orbit with as much fuel and oxidizer left as possible.

Whatever fuel and oxidizer is left can be considered "payload", so now build another one where you replace the leftovers with useful payload.

As you do this, experimenting with ratios and parts, you will quickly work out rough guides of what you need to make a spaceplane for whatever payload.

Best,

-Slashy

Edited August 27, 2015 by GoSlash27

[Greenfire32]

The easy way to do it is this:

Build a spaceplane with nothing but fuel and oxidizer. Optimize the ascent profile to get it to your desired orbit with as much fuel and oxidizer left as possible.

Whatever fuel and oxidizer is left can be considered "payload", so now build another one where you replace the leftovers with useful payload.

As you do this, experimenting with ratios and parts, you will quickly work out rough guides of what you need to make a spaceplane for whatever payload.

Best,

-Slashy

Man I never though of doing it like this...Thanks Slashy, maybe this will re-invigorate my currently-shutdown space plane assemblies!

[GoSlash27]

Greenfire32,

Thanks! It's responses like this that make all the mucking about worthwhile.

Go forth and space like a rockstar!

Best,

-Slashy

[bigcalm]

Halp. Yeesh, I'm finding SSTO's really hard. I've built some successful Mk2-based SSTO's on a smaller scale that can orbit, de-orbit, and land successfully. I'm now trying to scale up to a Mk3 variant and I'm really struggling - either the wings break off on de-orbit, or I spend an inordinate amount of time and fuel breaking the sound barrier, or everything just heats up and then bits start breaking off. Or it gets uncontrollable at 23k or desperately wants to touch noses with the ground on re-entry.

Essentially, I'm trying to build an SSTO suitable for Laythe that can be docked to my standard shunt (max weight ~60 tons -- assume unfuelled as I send tankers in the same flotilla). My criteria here are: Must be able to work on Kerbin ; Must have mining and refining facilities ; Must have some crew capacity ; Must have science gubbins ; Must be under 60 tons unfuelled).

Here's the payload:

So that's a Mk3 long cargo bay with everything I need in it.

My current plane that goes around this utilising 6 rapiers looks like this (craft file):

I'm oscillating between a "nearly working" solution - which I then need to tweak just slightly and end up with a completely new problem which requires a complete redesign.

I think I'm looking for maths more than anything -- for every x tons of weight I need x TWR, y liquid fuel, z oxidiser and to use a certain ascent profile.

Here's the most succesful so far -- but the docking port snapped off despite struts on ascent and it didn't have enough PB-NUKs to do anything useful. A small tweak and it stopped working.

Halp.

[Geschosskopf]

Ok, my bad. I mean a useful plane. It needs to have a purpose beyond getting a pilot to orbit, such as cargo hauling or even a crew cabin.

I build spaceplanes with at least 1 Mk2 crew cabin and a probe core. Or 1 cabin and a cockpit, or 2 cabins and a probe core. This (and a docking port and RCS to dock with) are the minimums I consider as making a "useful" spaceplane. I don't do payload spaceplanes as most of the payloads I launch won't fit in even a Mk3 cargo bay.

Anyway, designs using 2 crew parts (cabins and/or cockpits) and just 2 RAPIERs typically have a TWR of about 0.8 in jet mode. You can get such a thing to orbit provided you're willing to spend about 20-25 minutes of your life on it. You spend about 2/3 of that time SLOWLY climbing to about 13-15km at 150-250m/s, then you spend a couple minutes in a shallow dive from there back down to about 10km, which is necessary to break the sound barrier and exceed 400m/s. Then it's several more minutes in a very shallow climb from 10km up to 23km or so where the jets fall dead and you switch to rocket mode, then a minute or so rocket burn to get above the air. Once there, however, you can warp ahead the 3-5 minutes to your circularization/rendezous set-up burn.

Because of this, I REFUSE to build any more "useful" spaceplanes with just 2 RAPIERs. It's just way too time-consuming to launch them, not just in actually doing it but also in redoing it a bunch of times until you figure out how to make it work after numerous not-quites. Plus, they tend to be rather bigger because the engines (both in jet and rocket mode) have to run for a long time. I find it much better to use 4 RAPIERs and get a TWR > 1.

[Clipperride]

I did get one to orbit, finally, but with barely enough fuel to get back at 75km. I switch out the Rapiers for TurboJet/Aerospike combo. I guess the Rapier is just dead weight now, ISP is far too low. This will be my last plane, It's just not fun anymore, the only cargo I was able to carry was a fuel tank full of fuel, to deliver the empty to space. Maybe I'll see if I can find an old copy of 0.90 with FAR.

It can be done! (But if, as mentioned, its not fun then it may not be worth it)

The "Brute" I built can get into orbit with 1560 fuel and 880 Oxidiser left. With two LV-N and two Rapier engines in line with the CoM, that's quite a bit of delta V to play with. Each new version of my space plane is a little better than the last. Well, until I tried the Mk3 parts, but that's another story...

The little test plane I built is (front front to back)

CH-J3 fly by wire avionics hub.

NCS Adapter

Mk2 to 1.25m Adapter

Mk2 Inline Cockpit

Rocket Fuselage.

Bicoupler

2x Engine Precoolers

2x Engines I want to test

A couple of AV-T1 Winglets on the Precoolers

Big S Delta Wing (usually half full of fuel) with Elevon 1 and 4 at the end of each wing.

Landing gear.

I must have flown 50+ ascents over the last couple of days, trying different techniques. Bollting on a couple of Structural Pylons, Preschoolers, Shock Cone and additional engines for comparison.

But, for me, a lot of the fun of KSP is the trial and error along with the sense of satisfaction when that darn thing actually performs how you planed it! :-)

- - - Updated - - -

Good thinking! I never remember to shuffle fuel around on my winged beasties. It's become second nature to check on rockets after an unfortunate incident with faulty fuel line placement on leaving Minmus

[Nich]

Alshain have you considered that your physic.cfg is messed up? If you really do have that much experience you may be running with 1.0.2 drag with 1.0.4 ISP which would make SSTOs nearly impossible IMO

If you really want a challenge try a wheesly SSTO(and yes I was successful). I spent a month trying to make one of those. Then tried a rapier build and it was SSSOOOO easy.

[GoSlash27]

I must have flown 50+ ascents over the last couple of days, trying different techniques. Bollting on a couple of Structural Pylons, Preschoolers, Shock Cone and additional engines for comparison.

But, for me, a lot of the fun of KSP is the trial and error along with the sense of satisfaction when that darn thing actually performs how you planed it!

Clipperride,

I suppose it's just another example of "diff'rent strokes". I'm with you; the trial and error/ experimentation/ note taking/ failure/ eventual success and deeper understanding... For me, that's the *most fun* part of KSP. I always seem to enjoy it more when I'm in the laboratory fighting to understand than I do just managing missions I've already sorted out.

I suppose this is just another part of KSP's broad appeal.

Best,

-Slashy

[Val]

That assumes you only want a 75km orbit. It should not be that fine a line if you want to go any higher than that. It doesn't work. I want to do more then go to barely orbit. I want to rendezvous with a station at 300km, while carrying cargo or personell for it, but if the line is that fine, then it isn't possible. I'm sorry, they really ruined planes in this game. I'm done.

I made you an SSTO, so you can try something that works.

To launch it to orbit follow these steps.

1. Full throttle, SAS on, Stage.
   
2. Let it use the full length of the runway, then set the nose 5 degrees above horizon.
   
3. When speed reaches 300-350 m/s lift the nose to 10 degrees above horizon.
   
4. Don't touch anything until it reaches 24 km altitude.
   
5. At 24 km press 1 to switch Rapier Mode
   
6. At 27 km set the SAS to follow Prograde.
   
7. Throttle down when AP is above 80 km.
   
8. Coast to space and circularize.
   
9. Plan a Rendezvouz with your station.
   

Javascript is disabled. View full album

Craft file

Edit: Fuel lines are only there to help MJ see the correct dV.

Edit 2: And I only just now noticed that KER and MJ don't report the same dV. I wonder which is correct?

If you feel up to trying something bigger and a bit more complex then you can give this one a go: SSTO H-6 Drone Mk.3

Edited August 28, 2015 by Val

[Nothalogh]

Bolting on Preschoolers

I try to keep them in the passenger compartment, myself

[Geschosskopf]

I'm a fan of the Cherry Poppin' Daddies so "Go Slash" reminds me of one of their songs. Is that relavent to your handle?

Anyway.....

I suppose it's just another example of "diff'rent strokes". I'm with you; the trial and error/ experimentation/ note taking/ failure/ eventual success and deeper understanding... For me, that's the *most fun* part of KSP. I always seem to enjoy it more when I'm in the laboratory fighting to understand than I do just managing missions I've already sorted out.

As a holder of an engineering degree, I groove on this myself. But OTOH, my engineering degree is Industrial/Manufacturing Engineering so I have balance pure geeking out on technicalities with a quiche-eating MBA's concern for budgets and schedules. So I put a value on the time I spend bashing stuff into flyable form. Doing KSP R&D requires "mass quantities of alcoholic beverages" for inspiration but there's a break-even point down that road. Eventually, it's just easier to slap however many boosters under your payload and be done with it. Or, in the spaceplane realm, slap however many engines on it will get it there, But usually it''s the rocket that wins.

I suppose this is just another part of KSP's broad appeal.

No doubt. I think there are a few folks who play KSP while sober

[GoSlash27]

I'm a fan of the Cherry Poppin' Daddies so "Go Slash" reminds me of one of their songs. Is that relavent to your handle?

Actually, no (though good guess). It's a reference to Kordell "Slash" Stewart; the Pittsburgh Steelers' quarterback from the mid- 90s to early 2000s. I was 27 years old when I adopted it (roughly when dinosaurs ruled the Earth) and I've kept the same handle ever since.

My nick is probably older than most members of this forum

Best,

-Slashy

/get off my lawn!

[peachoftree]

Ok, my bad. I mean a useful plane. It needs to have a purpose beyond getting a pilot to orbit, such as cargo hauling or even a crew cabin.

Sure. in FAR, I have a plane that can deliver a modest payload (confined more by the mk2 form factor than by weight) all the way to minmus orbit, or to the surfice if it can refuel there:

Plane:

The lander is on the right:

Sorry I don't have a better pic of the plane, travelling atm and don't have a KSP-worthy computer on hand.

Edited August 28, 2015 by peachoftree

[Clipperride]

. Preschoolers are much cheaper than qualified mechanics! (Pesky auto correct!)

- - - Updated - - -

Clipperride,

I suppose it's just another example of "diff'rent strokes". I'm with you; the trial and error/ experimentation/ note taking/ failure/ eventual success and deeper understanding... For me, that's the *most fun* part of KSP. I always seem to enjoy it more when I'm in the laboratory fighting to understand than I do just managing missions I've already sorted out.

I suppose this is just another part of KSP's broad appeal.

Best,

-Slashy

Reaching for pen and paper is always a sign that I'm enjoying a game. When I start printing off forms to record data, then I'm hooked. The good Lady wife commented the other day that my KSP paperwork is far more organised than such trivia as the household accounts. OK, I admit the colour coded paperclips may be taking things too far

[Geschosskopf]

My nick is probably older than most members of this forum

Hehehe, you young whippersnapper, my moustache is older than your nick . I reckon I got a good decade on you.

[KerikBalm]

Then why can't they get to orbit? It makes no sense, I can't get a 23 ton craft with 2 freaking rapiers to orbit.

They can... please provide pics of your craft.

https://scontent-mxp1-1.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/s720x720/11896172_10103816242975313_2719409978987052993_n.jpg?oh=b78ea2803225c6a9ac74da2c48022c72&oe=5639D17B

https://scontent-mxp1-1.xx.fbcdn.net/hphotos-xaf1/v/t1.0-9/s720x720/11822430_10103801336797413_628457289837148052_n.jpg?oh=e03d901905c4e6cc6d1015dc9181bea3&oe=563A9279

https://scontent-mxp1-1.xx.fbcdn.net/hphotos-xtf1/t31.0-8/s720x720/11402323_10103689531740643_2498072407316109652_o.jpg

^ no, this was not there to refuel at the station (even if it was, it takes more dV to get to Mun, capture, and rendevous, than it does to get into a 300x300 km orbit), in fact, it can even make "deposits" at the station (many of my early SSTOs to the Mun station would deposit excess oxidizer, until I started flying with less oxidizer because my station was full of Oxidizer... they can also deposit excess LF - but LF is relatively expensive, and once I got ISRU running, I like to come back with a nearly full load of LF)

[Clipperride]

Hehehe, you young whippersnapper, my moustache is older than your nick . I reckon I got a good decade on you.

The first game that hooked me was Pong at 5p a go - does that put me in the running for oldest in thread? Lol

Although good too see the senior players can still juggle gaming with life's responsibilities.