Foil. SSTM Crew Trainer.

[CrashTestDanny]

I agree about the name - plus a foil is a quick, fast, and light weapon - just like this ship.

[CrashTestDanny]

One quick note - the d/l file only has one solar array but your reference photos show two. Is that intentional?

[Redshift OTF]

Yes I just noticed that. I would also say this plane doesn't like yawing much. It seems that yawing to one side increase the lift on the vertical tail pieces that is greater than the input and it moves in the opposite direction. Apart from that it looks good.

[SpaceplaneAddict]

I just built a SSTM right now.

I feel happy that I could do something Rune could.

[Redshift OTF]

Going well, then one engine swaps to closed cycle without the other at 18km and ruins the whole flight. I have homework, so I'll try to learn how to flight straight later.

I think you should be able to get up to around 30km before you engage closed cycle.

[Camaron]

I think you should be able to get up to around 30km before you engage closed cycle.

I know. I have no idea why one engine switched like that. It didn't happen again.

Finally orbited the darn thing. I certainly don't have 5,000dv left, only made it to LKO with 1463 total LF. I won't become a skilled pilot overnight. Also, I'm not very patient with 20-minute ascents.

Also, after losing several life-and-death conflicts with the evil tailfin, I rebuilt it into a much more stable (and slightly lighter) version that I was able to get along with. It's a tad uglier tho.

This design tweak is overall a half-ton lighter than the original. Someone with pilot training could make some serious progress with that. Maybe we could actually crack 5k dv on orbit with a skilled flyer?

Later....(edit)

Dropping 0.703 tons or the dryweight makes an enormous difference! Managed to take 1821 LF to orbit this time with the same substandard piloting.

Here is my final modification before attempting to build my giant version, which I'm thinking of calling "Runebane".

Edited October 18, 2015 by Camaron

[Rune]

It's enough challenge building an SSTO and you made one to do this, definitely deserves REP but I can't rep you again yet and I am ok with that its a good thing to spread the love around, I'll catch you later on that rep

Thanks! And yeah, spread the love, plenty of amazing contraptions out there.

Very nice.

I just did a similar training run with my XP Bus.

Yours looks to be much less expensive though.......

As far as the name goes.... Foil for sure. Since a foil is in fact, a training implement to use to learn a rapier.

I agree about the name - plus a foil is a quick, fast, and light weapon - just like this ship.

Yup, I think an edit of the OP is in order, I also quite like the name.

One quick note - the d/l file only has one solar array but your reference photos show two. Is that intentional?

That is the kind of stupid mistake that comes from over-editing a file, you pick it upto move it, forget to set symmetry, and... I'll fix it ASAP!

Yes I just noticed that. I would also say this plane doesn't like yawing much. It seems that yawing to one side increase the lift on the vertical tail pieces that is greater than the input and it moves in the opposite direction. Apart from that it looks good.

Yeah, the anhedral on the tailplanes is actually intentional, but it didn't work the way I expected. The idea was that, although unstable in roll, yaw input would tend to roll the plane the right way for turning, unlike the more common dihedral tailplanes. In practice, though, unless you are good at tapping the keys just the right way (or have a joystick and/or tweak the control surface deflection), if you max out the yaw input you get a control surface reversal and yeah, it works crappy (tough gentle turns are manageable with practice). I think it is because it has too much static lifting surface and the moving control surfaces respond too much too soon to input. But it looks so good...

I just built a SSTM right now.

I feel happy that I could do something Rune could.

The good thing about KSP is that since we all have the same pieces, with a bit of practice and learning from one another, everyone can do the same things.

I think you should be able to get up to around 30km before you engage closed cycle.

I actually engage them at about 22kms(and ~1,350m/s), over that you start losing vertical speed and burn precious liquid fuel for a marginal increase in horizontal speed.

Snip

Yup, that is a sensible design tweak. But aesthetics! Also, those RCS ports, mind them: their temp rating is 1,500º, so you are going to see explosions if you aerobrake vigorously. And, KER is screwing with you on the dV readouts: you don't have quite 5km/s, but you have way more than 2, it is not counting the fuel on the wings and engine nacelles since you have to pump it to the Nerv manually.

Rune. Man I missed a full-fledged keyboard.

[Redshift OTF]

So this is a great challenge. Build an SSTM. But I am struggling to build something as good as yours Rune possibly because my ascent profile is poor. What's the best way to get this to orbit? Climb to 11-12km go horizontal until thrust is maxed out and orbital speed is around 1350 m/s then climb about 30 degrees on closed cycle? Or do you have a better way?

[Rune]

So this is a great challenge. Build an SSTM. But I am struggling to build something as good as yours Rune possibly because my ascent profile is poor. What's the best way to get this to orbit? Climb to 11-12km go horizontal until thrust is maxed out and orbital speed is around 1350 m/s then climb about 30 degrees on closed cycle? Or do you have a better way?

I actually go for minimal pilot input. I settle on about 10-12º AoA, which in this design means it will go transonic on its own below 10,000m. I might have to let it fall a bit to keep velocity increasing at all times on less sleek designs, or if I climb too steep, as Kerbin curves under me and AoA increases on its own. Once the velocity starts to ramp up seriously at about 12-14kms, I drop the nose again to about 10º with the prograde autopilot to maximize the time at full thrust and take vertical velocity down to about 50m/s. Once done that, back to normal SAS and touch nothing. As I speed up the vertical velocity and AoA increase on their own with minimal drag losses. When vertical velocity stop increasing at about 22kms and TWR 0.5, engage the RAPIERs in closed cycle to get outside of air quickly (again, don't touch the heading, by now your AoA will be closer to 15-20º over the horizon), and only engage the prograde autopilot once you are over 1,800m/s.

Also, lift and sleekness. The more you lift at lower AoA, the less drag you will have, which means the faster you will go, and also the smaller AoA you need to lift the same weight, so the less drag you have... it's a virtuous cycle.

Rune. Also, low wing loading allows low TWR, which allows a big mass ratio.

[CrashTestDanny]

I know. I have no idea why one engine switched like that. It didn't happen again.

Finally orbited the darn thing. I certainly don't have 5,000dv left, only made it to LKO with 1463 total LF. I won't become a skilled pilot overnight. Also, I'm not very patient with 20-minute ascents.

Also, after losing several life-and-death conflicts with the evil tailfin, I rebuilt it into a much more stable (and slightly lighter) version that I was able to get along with. It's a tad uglier tho.

This design tweak is overall a half-ton lighter than the original. Someone with pilot training could make some serious progress with that. Maybe we could actually crack 5k dv on orbit with a skilled flyer?

Later....(edit)

Dropping 0.703 tons or the dryweight makes an enormous difference! Managed to take 1821 LF to orbit this time with the same substandard piloting.

Here is my final modification before attempting to build my giant version, which I'm thinking of calling "Runebane".

Check my math post - 2700 is probably pretty accurate. and that being the case, you flew a much better ascent than I did. The 5k that MechJeb and KER reported for my flight was really more like 2400. But 2400 is plenty to do the mission that Rune built the ship for.

I think the best improvement you could make if you want to orbit with more delta-v would be to attach a pair of kickbacks to the wingtips!

Danny

[Rune]

There! The file updated with the right number of antennae and solar panels. And a ever so slightly lower anhedral on the tail to minimize the roll instability... not fix it. Damn it, I like how it looks too much! I hope you guys will forgive me?

- - - Updated - - -

Check my math post - 2700 is probably pretty accurate. and that being the case, you flew a much better ascent than I did. The 5k that MechJeb and KER reported for my flight was really more like 2400. But 2400 is plenty to do the mission that Rune built the ship for.

I think the best improvement you could make if you want to orbit with more delta-v would be to attach a pair of kickbacks to the wingtips!

Danny

You know, you made me run the tests myself and it doesn't take that long to install a couple of fuel lines on the SPH and fiddle with fuel levels... so now we have a definite answer! With 1766 units of liquid fuel (the ascent I showed on the album had 1770, so certainly doable), and the monoprop spent (always burn the lowest isp fuel first!), I clock 3,250m/s of dV on the nuke. Plus some change of actually burning the monoprop for something useful, or not taking it in the first place... call it 3.3km/s So, given the 1.43-2.15 TWR rating on Mun with such a fuel load, yeah, SSTM is certainly possible, and downright easy. Visiting both moon's surfaces on the same flight... iffy. You would definitely need some fancy piloting to do the Mun-Minmus transfer very efficiently. But hey, you could always land the kerbals on their backpacks and save ~300m/s from the mission budget, right?

Rune. The more you know...

[CrashTestDanny]

Dude - 3250 is with you flying it - not me... But I'm not complaining; this craft has the bank account to handle the mission you specified and come home with 800 or more to spare (with me flying it). While 800 does not get me a Munar insertion, landing, and ascent, it certainly gives me that fat margin that I love so much... And if I want to add to the mission, I know where the kickbacks are stored!

Danny

[Trios]

I actually go for minimal pilot input. I settle on about 10-12º AoA, which in this design means it will go transonic on its own below 10,000m. I might have to let it fall a bit to keep velocity increasing at all times on less sleek designs, or if I climb too steep, as Kerbin curves under me and AoA increases on its own. Once the velocity starts to ramp up seriously at about 12-14kms, I drop the nose again to about 10º with the prograde autopilot to maximize the time at full thrust and take vertical velocity down to about 50m/s. Once done that, back to normal SAS and touch nothing. As I speed up the vertical velocity and AoA increase on their own with minimal drag losses. When vertical velocity stop increasing at about 22kms and TWR 0.5, engage the RAPIERs in closed cycle to get outside of air quickly (again, don't touch the heading, by now your AoA will be closer to 15-20º over the horizon), and only engage the prograde autopilot once you are over 1,800m/s.

Also, lift and sleekness. The more you lift at lower AoA, the less drag you will have, which means the faster you will go, and also the smaller AoA you need to lift the same weight, so the less drag you have... it's a virtuous cycle.

Rune. Also, low wing loading allows low TWR, which allows a big mass ratio.

I just downloaded this craft and tried this precise ascent profile. Everything was going swimmingly, I had about 1300 m/s at 22k when the power fell off the rapier's, so I hit number 2 and engaged closed loop. My craft continued to accelerate and hit an apoapsis of....55k at flameout.

However, I think my game may be seriously bugged, because while writing this post and allowing the craft to come back down on prograde autopilot, the plane overheated and Val was killed. I can't see any SSTO overheating when it didn't even make it to orbit...

Strange behavior.

EDIT:

Tried again, got to orbit this time. I engaged the nuke along with the rapier's, and I got just outside of atmo when I ran out of oxidizer. Currently sitting in a 99 x 93 km orbit with 1783 liquidfuel left. After transferring what would fit into the central tanks, KER says I have 2305 m/s left, and it's not counting 444 units. So I don't think it's 3250 m/s, but it's close. Nice craft.

Edited October 19, 2015 by Trios

[Rune]

Dude - 3250 is with you flying it - not me... But I'm not complaining; this craft has the bank account to handle the mission you specified and come home with 800 or more to spare (with me flying it). While 800 does not get me a Munar insertion, landing, and ascent, it certainly gives me that fat margin that I love so much... And if I want to add to the mission, I know where the kickbacks are stored!

Danny

Well Trios just flew her better than I did on the test flight... It's not that hard it seems! But yeah, she is meant to have a huge margin on the reference mission, so you can fool around a bit and fail, and she will still take you home safely. Or, cut on travel time if you are feeling brave...

I just downloaded this craft and tried this precise ascent profile. Everything was going swimmingly, I had about 1300 m/s at 22k when the power fell off the rapier's, so I hit number 2 and engaged closed loop. My craft continued to accelerate and hit an apoapsis of....55k at flameout.

However, I think my game may be seriously bugged, because while writing this post and allowing the craft to come back down on prograde autopilot, the plane overheated and Val was killed. I can't see any SSTO overheating when it didn't even make it to orbit...

Strange behavior.

EDIT:

Tried again, got to orbit this time. I engaged the nuke along with the rapier's, and I got just outside of atmo when I ran out of oxidizer. Currently sitting in a 99 x 93 km orbit with 1783 liquidfuel left. After transferring what would fit into the central tanks, KER says I have 2305 m/s left, and it's not counting 444 units. So I don't think it's 3250 m/s, but it's close. Nice craft.

Well, I found out the dV for an ascent that left you with 1770 liquid fuel, so you don't have 3250m/s... you have slightly more. IF you burn the monoprop first, or dump it, if not you will have slightly less. Also, you just flew it to orbit better than I did on the test flight! You might have had some problems figuring out how the RAPIERs only kick you out of the dense atmosphere and you have to finish the trip to orbit on the nuke... but as you can see, it is not difficult at all once you familiarize yourself with the ship.

And I think it burned because it is so sleek on your failed try: as you went down with a small AoA, you didn't slow down at all, and you hit the lower atmosphere way too fast for that dense air. Just so you know what to do when reentering, pull the stick back until you are doing >45º AoA, and all of that wing surface will turn itself into one giant airbrake, slowing you down so high and fast, you might stall yourself out before you reach 20kms and see no temp gauges at all. Do it once with the aerodynamic force indicators open, and you will see what I am talking about, all the lift vectors suddenly become tiny and the drag vectors go huge.

Rune. Its funny how long the last drops of fuel will take you.

[Camaron]

...You know, you made me run the tests myself and it doesn't take that long to install a couple of fuel lines on the SPH and fiddle with fuel levels... so now we have a definite answer! With 1766 units of liquid fuel (the ascent I showed on the album had 1770, so certainly doable), and the monoprop spent (always burn the lowest isp fuel first!), I clock 3,250m/s of dV on the nuke.

Rune. The more you know...

With the modified version I was flying, I got a total of 3,912. I actually tested that by flying Rune's Sabrefoil To the Duna system. The first photo is from after reallocating fuel upon making orbit. The second photo is in orbit of Ike when that fuel ran out, and I took all of the remaining fuel to the center. I made it home but reentry is challenging. I didn't have the patience to work it out at the time, and started on my giant version.

Thank you Rune, this was the perfect plane to teach me how to build extreme-performance spaceplanes!

Edited October 19, 2015 by Camaron

[Rune]

I made it home but reentry is challenging. I didn't have the patience to work it out at the time, and started on my giant version.

Glad you made it! Next time, take the reentry flat on your belly pointing radial, it'll look scary but when you look at your speed/altitude, and notice that temp gauges are conspicuously absent, you'll thank me.

Thank you Rune, this was the perfect plane to teach me how to build extreme-performance spaceplanes!

I'm really glad that it took you on a building frenzy! That's the best thing I can inspire in people, so I'm happy.

Rune. It's short of returning the favor, after all.

[Camaron]

Glad you made it! Next time, take the reentry flat on your belly pointing radial, it'll look scary but when you look at your speed/altitude, and notice that temp gauges are conspicuously absent, you'll thank me.

In my modifications I caused the craft to be too forward-heavy for that sort of heavily angled re-entry, so I couldn't pitch up the way you had designed it.

[CrashTestDanny]

I figured out that KER and MechJeb both do the calculation of delta-V a lot better if you shut down the engines that are not in use...

Danny

[Rune]

In my modifications I caused the craft to be too forward-heavy for that sort of heavily angled re-entry, so I couldn't pitch up the way you had designed it.

Oh, that makes sense. You moved the RAPIERs forwards, and I always take extreme care in how I place my tankage so the CoM changes as least as possible with fuel levels. But if you move them backwards again, you should get the right weight distribution back.

I figured out that KER and MechJeb both do the calculation of delta-V a lot better if you shut down the engines that are not in use...

Danny

Yup, and they also take into consideration the staging order, so do put any unused engines of separate, later-firing stages.

Rune. I honestly didn't think this little bird would generate such a positrive response!

[arkcane]

I cant seem to get it into orbit, obviously i am doing it wrong i just dont know why, iv read the description from earlier and i still cant make it work. If anyone has or wants to make a video Id appreciate it a lot

[Rune]

I cant seem to get it into orbit, obviously i am doing it wrong i just dont know why, iv read the description from earlier and i still cant make it work. If anyone has or wants to make a video Id appreciate it a lot

In what portion of the ascent are you having issues? Mostly it's a hands-free ascent, so tell me which of these milestones you can't hit, and I'll tell you what you are most likely doing wrong:

-Go transonic at about 10,000m.

-Drop the nose enough, early enough during the supersonic ascent, that you get to 22kms with about 1,300m/s of speed and more than 150m/s of vertical speed. It's mostly a matter of hitting the right angle at the right time, then doing nothing.

-Manage the excruciatingly long climb to orbit without going past your apoapsis and start falling unknowingly. Happens to the best of us if you don't keep an eye on time to apoapsis.

Depending on which part you are having issues with, it could be a number of things, and I'll be glad to assist you so you master this low TWR type of ascent.

Rune. They are quite useful to know how to do!

[Redshift OTF]

Here's my best effort so far.

Javascript is disabled. View full album

Ended up with 3550 in a 100km orbit. Same payload, (Mk2 cockpit, passenger module and docking port with all the monoprop), but a heavier ship. 65.2 tons and 74 parts. I haven't added the RCS thrusters yet though. A slight difference is 2 of the Rapiers are angled down to provide more vertical lift at a shallower pitch reducing drag. Ascent was different. Go transonic at 10km reach speed of 1550 m/s @ 26km with vertical speed at 170 m/s.

This should be a challenge because it is not easy. But thanks for the inspiration Rune!

[Trios]

Here's my best effort so far.

http://imgur.com/a/OWkDc

Ended up with 3550 in a 100km orbit. Same payload, (Mk2 cockpit, passenger module and docking port with all the monoprop), but a heavier ship. 65.2 tons and 74 parts. I haven't added the RCS thrusters yet though. A slight difference is 2 of the Rapiers are angled down to provide more vertical lift at a shallower pitch reducing drag. Ascent was different. Go transonic at 10km reach speed of 1550 m/s @ 26km with vertical speed at 170 m/s.

This should be a challenge because it is not easy. But thanks for the inspiration Rune!

I love how the swept wings make it look like it has F-14 style variable-sweep wings. The lack of a vertical tail surface makes this thing look incredibly unstable in yaw.

[Redshift OTF]

I love how the swept wings make it look like it has F-14 style variable-sweep wings. The lack of a vertical tail surface makes this thing look incredibly unstable in yaw.

I did just have 1 tail fin and I found it was much more yaw than I needed so I swapped it for 2 small elevons to reduce drag and it flies fine. I'm still not sure if I've got the ascent 100% especially considering the DeltaV you had left in the Foil. What ascent do you use to exit the atmosphere just as the oxidiser runs out?

[Rune]

Here's my best effort so far.

http://imgur.com/a/OWkDc

Ended up with 3550 in a 100km orbit. Same payload, (Mk2 cockpit, passenger module and docking port with all the monoprop), but a heavier ship. 65.2 tons and 74 parts. I haven't added the RCS thrusters yet though. A slight difference is 2 of the Rapiers are angled down to provide more vertical lift at a shallower pitch reducing drag. Ascent was different. Go transonic at 10km reach speed of 1550 m/s @ 26km with vertical speed at 170 m/s.

This should be a challenge because it is not easy. But thanks for the inspiration Rune!

Looking good! But I feel obliged to warn you, those airliner wins will overheat quickly, their temp rating is ludicrously low. And them being in the leading edge, that could be an issue... Anyhow, regarding you sub-Foil performance: I think that RAPIER switch speed is waaay too high. How do you even go over 22kms and 1,350? The RAPIER thrust goes to hell! I recommend switching sooner to get a less shallow angle, you may be incurring huge gravity losses in the upper atmosphere. Oh, and this comment:

What ascent do you use to exit the atmosphere just as the oxidiser runs out?

You don't actually leave the atmosphere when the oxidizer runs out. But if you run out of air and switch RAPIERs to LFO (while turning on the nuke too!) at ~1,350m/s @ 22kms, as I said, and then touch nothing so the bird goes from 10º AoA to about 15º, then when they run out your apoapsis is already out of the atmosphere, or sufficiently close that keeping on thrusting with the nuke alone on that heading will push time to apoapsis up.

Rune. Oh, and angling the RAPIERs is giving you some cosine losses... may be irrelevant in airbreathing flight (or not), but it'll hurt you on the rocket climb.