Single Tank Tylo: A mission on the edge of possibility?

[Lirtosiast]

Back in 2016, Hazard-ish used a nuclear engine with edited thrust and I_sp values to land on Tylo and return, with the only source of fuel being a single large fuel tank. Here is a tentative stock, optimized version of this mission, using a mix of Hazard-ish's numbers, my own dV estimates, and Kerbin-Jool numbers shown to be possible in the past. The craft is like Hazard-ish's but with a large Mk3 fuselage, 5 stock nuclear engines, and an unknown optimized Kerbin ascent stage. Payload/structural mass is assumed to be 1.5 tons. There appear to be fewer possible approaches for this mission compared to SSTO Tylo (which given the other thread seems impossible)

My mission profile with dV estimates is as follows:

Maneuver	dV (m/s)
Put the vehicle into orbit. Must use less than 13.5 tons of liquid fuel. May be doable with electric propellers. Remaining mass: 60.15 tons.	-
Use Mun-Mun-Eve-Kerbin-Kerbin gravity assists to get a Jool encounter in 1011 m/s a la PLAD. Difficult because the max acceleration of the craft is only 5 m/s^2.	1011
Use a Laythe assist to capture in low Tylo orbit for 1020 m/s. (Capturing at low Tylo orbit from anywhere always costs 810 m/s)	1020
Do a 400 m/s horizontal landing on Tylo. High dV because your starting TWR is only 0.83 (landing TWR 1.15). Hazard-ish managed 150 m/s, already an impressive feat.	2500
Take off from Tylo horizontally at 500 m/s, dropping all but a single engine along the way. There is a slightly difficult calculation to determine exactly when the engines should be dropped; the optimum is to drop the last pair when the craft reaches 1700 m/s.	2533
Use a Laythe assist to get back home. For the last 100 m/s, use the EVA pack to push a 0.625m heatshield with a chair strapped to it. Use the Kerbal's parachute to land.	810+100
Total	~8050

I can't tell if this mission is possible or not. Margins are basically zero, so all of these difficult feats are necessary. It basically comes down to whether the Kerbin ascent, horizontal landing, and pushing the reentry vessel at the end are possible, but I'm not a good enough player to test any of those (only landed on Tylo once, and inefficiently at that, nor am I an expert on SSTOs or propellers). So my two questions are:

1) Will this mission plan work, if one can pilot the bloody thing? If not, why not?

2) Can anything be optimized further? I thought of a 300-400 m/s touch-and-go at Tylo, which probably makes the mission doable but isn't quite the same as a full landing.

Here's the analysis in spreadsheet form:

https://docs.google.com/spreadsheets/d/17JtG4sQc_FvpHZovDfvPAZIKkyoFxo45DA5bv964Zjw/edit#gid=0

(I'm new here so please move if this is the wrong subforum.)

 

Edited March 19, 2018 by Lirtosiast

[Dman979]

Hi, @Lirtosiast, and welcome aboard! This seems like a bit of a challenge, so I'm gonna move it to the challenges subforum.

I think it's gonna be fun to see if it's possible!

[AeroGav]

Single large mk3 liquid fuel fuselage.

Liquid fuel only launch from Kerbin.

Panthers and Rapiers (airbreathing only).     Panthers help us get supersonic , when they flame out - punch em off.     

When we hit airbreathing top speed - punch off the Rapiers.

When we pass above 50km - loose the wings.

After liftoff from Tylo, with safe AP reached, jettison most of the NERVs (space is full of radiation anyway,  what's crashing a few nuclear reactors between friends)

In 1.3 I built this liquid fuel only cargo ssto that did 50% payload fraction,   so if we're allowed to start dumping parts, we can potentially do quite well here.

 

I've been out of the game a few months and don't have much time to play today, or i'd probably knock up an entry!

 

 

[EpicSpaceTroll139]

ACK! Sorry for the double post. For some reason this didn't load earlier, so I thought I must have accidentally canceled the post, and made a new one.  

 

Edited March 19, 2018 by EpicSpaceTroll139

[Lirtosiast]

3 hours ago, EpicSpaceTroll139 said:

Heh. I actually had a conversation myself way back with Hazardish after the big fiasco thing regarding the Tylo  one tank possibility. He seemed to think it was at the edge of possibility, that he had resorted to the edits after banging his head against a wall "UGH THIS IS SO CLOSE TO WORKING!!!!", and I ended up working on some crafts that could theoretically achieve it [...]

Oh, interesting. Yeah, I decided the Mk3 tank would be the only possible approach pretty early on. What's your structural/payload mass? I've just been using 1.5 tons.

As for the gravity assists to Jool, I think we can just use the 1011 m/s number and find a route when we need to . PLAD said under 997 m/s is impossible anyway.

Did you take into account the low TWR on Tylo landing/ascent? It makes a pretty big difference; I don't think Tylo ascent will be achieved for under 2500 m/s or so with such a low TWR, and adding more than 5-6 engines reduces your delta-V budget too much.

Edited March 19, 2018 by Lirtosiast

[EpicSpaceTroll139]

Heh. I actually had a conversation myself way back with Hazardish after the big fiasco thing regarding the Tylo  one tank possibility. He seemed to think it was at the edge of possibility, and I ended up working on some crafts that could theoretically achieve it. I went for designs similar to Hazardish's original first, working on shaving every possible kilogram off the thing. Eventually I came to @AeroGav's conclusion that the large Mk3 fuselage with its liquidfuel would be a better tank to use, as with the large kerbodyne tank the oxidizer is only used during the initial ascent from Kerbin, and the empty oxidizer part of the tank is now dead weight. A much greater fuel fraction is achieved when we only use liquidfuel from a liquidfuel tank.

I could dig up the craft files and look at them. I recall I abandoned the thing because I realized I wasn't great with SSTO's, 

It also occurs to me that the addition of stress limits to the wheels in a KSP update since Hazardish did the thing could make it 10x harder to do the Tylo landing.

 

It occurs to me that significant fuel savings could be achieved during ascent from Kerbin if something similar to this helicopter/centrifugal-catapult montrosity by @Stratzenblitz75 could be made, only with much greater lifting capacity:

 

 

As for the "low" 5m/s^2 acceleration being a problem for the transfer, even lower accelerations can be dealt with use of multiple periapse kicks, though that's only applicable to the initial escape from Kerbin. It does require lots of planning ahead, as you have to account for the time it takes for the multiple orbits made inbetween the kicks.

Edited March 19, 2018 by EpicSpaceTroll139

[EpicSpaceTroll139]

2 hours ago, Lirtosiast said:

Oh, interesting. Yeah, I decided the Mk3 tank would be the only possible approach pretty early on. What's your structural/payload mass? I've just been using 1.5 tons.

<Snip>

Did you take into account the low TWR on Tylo landing/ascent? It makes a pretty big difference; I don't think Tylo ascent will be achieved for under 2500 m/s or so with such a low TWR, and adding more engines reduces your delta-V budget too much.

I'll take a look at the mass ratio of my craft in the morning.

As for the TWR, yes, you will want a decent TWR during ascent from Tylo, but keep in mind that a decent amount of fuel will have been used during the transfer an landing, bringing the TWR up. It should also be possible to, as in the video, gain a decent amount of velocity with the engines parallel to the surface, for which the TWR isn't as important.

Though I see... You're right that you might want decent TWR for the horizontal landing too. *Thinking*

 

Another: I believe my designs had 3 nuclear rockets. Should be interesting to see how TWR affects landing and takeoff on Tylo.

Perhaps for testing we could hyoeredit designs to low Tylo orbit with a given amount of fuel and test them. Granted this would probably take a while given how hard a 400m/s landing on hilly Tylo is, but it's better than doing the whole thing only to find the landing doesn't work.

Edited March 19, 2018 by EpicSpaceTroll139

[Lirtosiast]

@EpicSpaceTroll139 3 nuclear rockets? My spreadsheet gives a Tylo landing TWR of 0.96 with three engines, payload of 0.6 ton, and droppable landing gear of 1 ton. Of course you're landing at up to 500 m/s, which reduces effective gravity, so your effective TWR is 1.03ish... still, by the time you land you're pitching up at csc^-1(1.03)=80 degrees just to maintain altitude. If it's possible to land with acceptable dV from that it would be quite a challenge.

Testing is definitely a good idea. It would be a shame to have to cheat in unbreakable parts, because if horizontal landings don't work this mission is probably futile.

5 m/s^2 in Kerbin orbit isn't too low, but it's low in comparison to PLAD who used a spacecraft with approximately 30 m/s^2.

EDIT: Assuming 0.6t payload and 1t gear my calculator gives 2498 m/s with 3 engines compared to 1981 m/s with 5 engines for theoretical best Tylo ascent, and the additional mass makes it impossible to land. If the payload can be made as light as 0.6 tons, 4 engines might be the sweet spot.

Edited March 19, 2018 by Lirtosiast

[EpicSpaceTroll139]

Yah I think you're right that more engines will be needed for the Tylo landing. 

Anyways, this is one of the set ups I had:

I have now realized that the twr would be a problem, especially with the low-gear configuration. My idea on this thing was to bring in the landing similar to hazardish's, and at the last second pivot forward (backward? It's all weird when you're flying backwards) and land at an angle of 15 degrees or so on the forward wheels.

After takeoff the landing gear tray and eventually the outer two nukes (probably 3 or 4 in a working version) would be ditched and there would just be the center nuke.

My original idea was to have the whole thing aerodynamically stable when empty going retrograde, and use the rest of the craft as a sacrificial heatshield on return to Kerbin, but I think your idea with the kerbal pushing the 0.625m shield on EVA would work better.

Edit: This configuration's non-tank/engine mass is less than 500 kilograms.

Edited March 19, 2018 by EpicSpaceTroll139

[AeroGav]

7 hours ago, EpicSpaceTroll139 said:

Yah I think you're right that more engines will be needed for the Tylo landing. 

Anyways, this is one of the set ups I had:

I have now realized that the twr would be a problem, especially with the low-gear configuration. My idea on this thing was to bring in the landing similar to hazardish's, and at the last second pivot forward (backward? It's all weird when you're flying backwards) and land at an angle of 15 degrees or so on the forward wheels.

After takeoff the landing gear tray and eventually the outer two nukes (probably 3 or 4 in a working version) would be ditched and there would just be the center nuke.

My original idea was to have the whole thing aerodynamically stable when empty going retrograde, and use the rest of the craft as a sacrificial heatshield on return to Kerbin, but I think your idea with the kerbal pushing the 0.625m shield on EVA would work better.

Edit: This configuration's non-tank/engine mass is less than 500 kilograms.

My concept  was going to use the large size landing gears.   Tylo's terrain is pretty rough,  if you're planning any kind of rolling takeoff/landing i can't see the small ones surviving.  Given that each nuke weighs 3 tons,  this could  be the wrong place to scrimp.

With my space plane designer perspective, the above fuselage is horribly draggy (I am of course, rubbish at exo-atmospheric manuvering).     The abrupt end of the mk3 fuselage will cause much drag,   I was planning to put a mk3 engine mount on the back.   It has three 1.25m nodes and a 2.5m node in the center.     I was planning to put nukes on each 1.25m node  and then a 2.5m tri coupler in the middle with 3 more nukes.    A 2.5m decoupler can be used to dump half the nukes once takeoff from Tylo is assured.   That might be overkill ofc.

What to put on the front ?

Mk3 cockpit?   Heavy & heat sensitive.

The most aero option is actually another mk3 engine mount, so long as you fill all its 1.25m and 2.5m nodes and start all of those "fingers" with something pointy.  

mk2 pod on the 2.5m node and 1.25m nose cones on the small nodes?  Heavy but roomy...    or are we going with command chairs in service bays?

From a space plane perspective,  I should be able to reach orbit with the tank still 60% full at the very least.   In fact I might be able to bust 75%.    But even building a single stage lander to go from low tylo orbit to the surface and back again is very challenging and I flying the damn thing harder still (if it hasn't got wings, i struggle).

 

[EpicSpaceTroll139]

32 minutes ago, AeroGav said:

My concept  was going to use the large size landing gears.   Tylo's terrain is pretty rough,  if you're planning any kind of rolling takeoff/landing i can't see the small ones surviving.  Given that each nuke weighs 3 tons,  this could  be the wrong place to scrimp.

With my space plane designer... <snip>

...still (if it hasn't got wings, i struggle).

 

We might be able to go with the large stearable gear, and that's probably advisable given the wheel stress limits, but I think the Mk3 engine mounts would add too much dead mass during the rest of the trip (aren't they like 200kg each?). If possible it might be better to go with fairing caps (or one around the whole thing) which can be decoupled in near-space.

As for the Kerbal accommodations I have little doubt that seats will be used. We won't want to carry any service bays to Tylo though, so perhaps the seat as well should be under a fairing. 

Edit: but I'll look at what deltav margins the mounts would leave, maybe they're worth it if you think we could still have 75% fuel in orbit

Edit2: perhaps on the wheels, the medium gear should be used for the ones that touch down on the surface first and bear most of the weight, and the small gear can be used for the stability, or "nose" wheels.

Edited March 19, 2018 by EpicSpaceTroll139

[Lirtosiast]

I finished working out the math. First thing to note is that 5 engines is optimal, as I had guessed. 4 engines is theoretically better if the craft is extremely light, but 5 is probably realistically better since with higher TWR it's easier to land, easier to do gravity assists, and easier to circularize in Kerbin orbit.

Assuming there are 0.6 tons of payload and 0 tons of landing gear dropped on Tylo ascent, our Kerbin ascent budget is at MOST 20.2 tons of liquid fuel to get the craft into Kerbin orbit. This means a 59.6% full tank.

• For every ton of landing gear, we lose about 2.3 tons of ascent fuel (4.6% more fuel)
• For every extra ton of payload, we lose 2.9 tons of ascent fuel (5.8%)
• For every 100 m/s below 500 we land and take off at, we lose 2-2.5 tons (5%).

These numbers are fairly close but may change with piloting error.

So if we include the 0.7 ton Mk3 engine mount as payload; and also include 3 medium landing gear (0.75 tons), we will need a 67.1% full tank in orbit. Keep in mind this is with perfect piloting* and assuming we can land and take off at 500 m/s. If we can only land and take off at 400 m/s, we need 72.0% fuel in orbit. My spreadsheet (here) is fairly user-friendly now if anyone wants to plug in other values.

Should I start a separate "highest % fuel left in orbit" challenge so we can get an idea of the maximum possible fuel left in Kerbin orbit?

 

 

EDIT: Got the Euler's method approximation working for Tylo ascent. Next is the Tylo landing one. Turns out Tylo ascent takes slightly less fuel than I had calculated before.

EDIT: Works for Tylo landing now too. Calculations updated accordingly.

* EDIT again: However, I'm assuming a constant altitude takeoff, which is not quite optimal when engines are dropped. Here's what I mean: Attached is a graph of the pitch for a constant altitude ascent as a function of horizontal velocity. The sharp spikes are artifacts, but notice how the pitch abruptly rises when we drop the first pair of engines at 1050 m/s, and the second pair at 1650? Smoothing the pitch out to something like the red line would prevent cosine losses. In piloting terms, this means using the extra power of 5 engines to loft yourself up a bit so that when your TWR drops, you don't smash into the ground.

I'm not sure how much mass this would save though, and it's really difficult to calculate because now rather than optimizing for one variable, we're optimizing for a whole function: pitch as a function of velocity. Empirical testing with an actual Tylo lander is probably best.

https://imgur.com/a/qtMhQ

Edited March 20, 2018 by Lirtosiast

[EpicSpaceTroll139]

Considering we want to do 400-500m/s landings and takeoffs from Tylo, we should definitely look into the height map of Tylo. I have a kOS script that can find high and low points on a given body, and it shouldn't too hard to adapt it to look for places of a certain elevation, and then adapt that to look for flat areas. However I get the idea it might be better to have something looking at the height map from outside the game.

Anyways, my point is, we need to make sure that a place long and flat enough exists to do this.

[Ultimate Steve]

Hmm... this is interesting as well as most likely beyond my piloting abilities. I can build and run some numbers, though... electric props for initial Kerbin ascent will be useful, though.

If you were considering a parachute, then it's not necessary for two reasons - 1, the new personal chutes in 1.4, and 2 - Kerbals can survive a fall into the ocean at terminal velocity.

EDIT: 2 questions, what's the max speed and altitude one can feasibly reach with electric propellors, and how many rapiers do y'all think will be needed? I have three installed, more will probably be necessary.

Edited March 21, 2018 by Ultimate Steve

[FleshJeb]

@Lirtosiast I just replied to your PM with a novel. I should have checked your baseline level of knowledge first. 

As I said, expect to double the landing dV--It really starts running away below TWR 1.5.

I'm not likely to finish my KRPC CAL script anytime soon. I WAS going to do some testing with Throttle Controlled Avionics to do consistent, repeatable piloting.

[Ultimate Steve]

Anyone have a download link for a good electric propeller? I've been trying to make my own but it's not working out well.

[EpicSpaceTroll139]

57 minutes ago, Ultimate Steve said:

<snip>

EDIT: 2 questions, what's the max speed and altitude one can feasibly reach with electric propellors, and how many rapiers do y'all think will be needed? I have three installed, more will probably be necessary.

If you go back and take a look at the first few minutes of the video I posted by @Stratzenblitz75, you can see a contraption he made, which is effectively a large centrifugal catapult lifted by a quad-rotor, which is able to lift his relatively small spacecraft up to an altitude of 26500m or so and hurl it at a velocity of 1km/s.

It would be hard, but not impossible to build a similar contraption with higher lift capacity, swapping out the ion engines that spin the arm for reaction wheels, or maybe rapiers if we think it's worth the fuel. I believe increasing the lift capcity enough might just be a matter of replicating design, but with 8 rotors instead of 4 (I imagine the arm itself is significantly heavier than his spacecraft), so doubling the rotors would do a lot more than double the capacity) and reinforcing the central bearing. I believe autostruts take enough of the weight that the arm itself wouldn't need to be redesigned much.

I might try working on one of these, and I'll try to optimize the part count.

[Lirtosiast]

38 minutes ago, EpicSpaceTroll139 said:

[...] It would be hard, but not impossible to build a similar contraption with higher lift capacity, swapping out the ion engines that spin the arm for reaction wheels, or maybe rapiers if we think it's worth the fuel. [...]

Rapiers wouldn't be worth the fuel if the arm is significantly heavier than this craft. Besides, the thrust would be near zero anyway when stationary at 26000 m. Reaction wheels don't have increased leverage when you put them on the outside of the arms. I think the best approach is secondary propellers on the arms, fairly close to the hub but still far enough away to get leverage (if the arm tip velocity is 1 km/s, and propellers are only effective below 250 m/s or so, we need them 1/4 of the way down the arm). Part count would be a challenge though.

EDIT: They should probably be contra-rotating to avoid gyroscopic effects.

Edited March 21, 2018 by Lirtosiast

[EpicSpaceTroll139]

10 hours ago, Lirtosiast said:

Rapiers wouldn't be worth the fuel if the arm is significantly heavier than this craft. Besides, the thrust would be near zero anyway when stationary at 26000 m. Reaction wheels don't have increased leverage when you put them on the outside of the arms. I think the best approach is secondary propellers on the arms, fairly close to the hub but still far enough away to get leverage (if the arm tip velocity is 1 km/s, and propellers are only effective below 250 m/s or so, we need them 1/4 of the way down the arm). Part count would be a challenge though.

Yah I knew reaction wheels provided constant torque, hence why I suggested the rapiers.

I imagine on Strat's design a significant portion of the part count is batteries for the ion engines, which we won't need so that would slash the part count a good deal.

Perhaps props could be used to get the arm moving, but I kind of doubt they could get it going to a tip speed of 1km/s. Perhaps a single rapier at the tip of the counter weight beam could be activated once the arm is moving at high enough speed for it to generate some thrust.

Keep in mind the arm was heavy, but that was only relative to his small craft, and he was turning it with several ion engines. I don't think we would need to keep the rapier on for long, and it's at high altitude so it probably wouldn't use too much fuel.

Alternatively the nukes could be used, if we feel the rapier isn't worth it, or would have too little thrust. Remember as long as we are accelerating on the arm, we don't have to angle up to fight gravity, so it might be worth expending a small amount of fuel to accelerate while still on the arm.

Edit: I downloaded the Helios 4 and took the batteries and decorative wings off the arm. I haven't even removed the ion spacecraft or 20 or so ion engines and still the part count got cut by over 100.

Edited March 21, 2018 by EpicSpaceTroll139

[Ultimate Steve]

12 hours ago, EpicSpaceTroll139 said:

Yah I knew reaction wheels provided constant torque, hence why I suggested the rapiers.

I imagine on Strat's design a significant portion of the part count is batteries for the ion engines, which we won't need so that would slash the part count a good deal.

Perhaps props could be used to get the arm moving, but I kind of doubt they could get it going to a tip speed of 1km/s. Perhaps a single rapier at the tip of the counter weight beam could be activated once the arm is moving at high enough speed for it to generate some thrust.

Keep in mind the arm was heavy, but that was only relative to his small craft, and he was turning it with several ion engines. I don't think we would need to keep the rapier on for long, and it's at high altitude so it probably wouldn't use too much fuel.

Alternatively the nukes could be used, if we feel the rapier isn't worth it, or would have too little thrust. Remember as long as we are accelerating on the arm, we don't have to angle up to fight gravity, so it might be worth expending a small amount of fuel to accelerate while still on the arm.

Edit: I downloaded the Helios 4 and took the batteries and decorative wings off the arm. I haven't even removed the ion spacecraft or 20 or so ion engines and still the part count got cut by over 100.

I don't have much time today, but tomorrow I'll download that craft as well and attempt to modify it. I've also built the in-space part of the ship and optimized it the best I could. I solved the aero issue by putting it in a fairing, but that might be too heavy.

[0something0]

On 3/19/2018 at 5:47 PM, EpicSpaceTroll139 said:

As for the Kerbal accommodations I have little doubt that seats will be used. We won't want to carry any service bays to Tylo though, so perhaps the seat as well should be under a fairing. 

Edit: but I'll look at what deltav margins the mounts would leave, maybe they're worth it if you think we could still have 75% fuel in orbit

Are the fairings even worth it? Can't we just put the seat at the rear end of the ship next to the engines.

[KingDominoIII]

I wonder, what about those new Saturn V replica tanks?

[Lirtosiast]

They have the same mass ratio as the 3.75m parts (so the same payload fraction to orbit etc. would be needed); also they're LFO tanks, so nukes are out. This doesn't completely rule it out, but anything with the large tanks would have less payload fraction than a NERV design.

Edited March 25, 2018 by Lirtosiast

[AeroGav]

Well guys,  I finally spent a couple hours doing my own take on this.

The mk3 tank has a mk3 mount at both ends for streamlining purposes.  Unfortunately the stock game does not have a mk3 decoupler, so these must come all the way to Tylo and back.

The 3 small nodes on the front adapter has nukes on them.   I used the rotate tool to make them face backwards rather than forwards , and the offset tool so their exhaust clears the hull.  The medium size, central node has a 2.5m nose cone with stack separator, so we can get rid of this cone once we're in space.

At the back, we have 2 big reaction wheels then a tri coupler mounted to the big centre node, and in turn we have 3 more nukes on that tri coupler.

There is a stack separator to blow off the tri coupler, and its 3 nukes, once we're safe in ascent from Tylo and no longer need the thrust.

For the small nodes on the rear facing mk3 mount, we have two occupied by nose cones , again on decouplers,  and the top one has a mk1 lander can for cosseting Jeb.   The back of this can has a 1.25m parachute.   It should impact nose first and the nukes will certainly smash , but there'll be plenty of crumple zone between the hard stuff and our little green friend.

Thus, my own OCD, and the Kerbal Gods of Aerodynamics are satisfied.

Hypersonic airbreathing propulsion comes via 3 rapiers,  and sordid business of actually getting through the sound barrier is aided by a quartet of Panthers.

I haven't played Kerbal for months and the game has updated since,  and i haven't bothered to rerun drag tests on different parts.  Also,  Correct CoL  aerodynamics aid does not appear to work on the latest version, so I had to resort to trial and error to balance the thing.      This is the first flight that actually got above 300m altitude.   All the other test filghts were aborted right after liftoff, when i realised it flew like a pig or kept pulling to one side.    I'm currently in the grips of an MMORPG addiction so won't get time to make this as polished as my other products.

But anyway . of you're brave of heart, the craft file is here.   

https://www.dropbox.com/s/yvmyktobdyauk7m/tylo thunder.craft?dl=0

 It's actually reasonably tame to fly around but the landing gear design could use some work, it is prone to "wheelbarrowing" and flipping over on takeoff.   I like my spaceplanes to hold prograde within 0.2 degrees no matter how much thrust the engines are making or how much fuel is burned off, this one is less accurate but acceptable.

Action group 1 toggles afterburner.

Action group 2 deploys trim flaps that lower AoA by about 1.7 degrees.

Action group 3 retracts trim flaps.

Action group 4 is nose up trim.

 

Alternatively if you just want the save file after reaching orbit, to see how it handles itself in space, save here -

https://www.dropbox.com/s/gwusik0pe47jzje/TYLO SPACE.sfs?dl=0

 

Video of the test flight here -

As you can see , the left rapier snagged on the fin and we ended up dragging it most of the way to orbit.  Probably made a lot of drag too, since it wasn't aligned prograde anymore.

Best solution is to move the vertical stabilizers  outboard, shifting that engine up or down will mess with centre of thrust and cause drag from the plane not holding proper prograde/be a pig to fly. In turn you'll need to shift the Panthers out a bit, but that should be straightforward as they're in a symmetrical pair, unlike our radial Rapiers.

In space, we had a bit over 5800 dv.    You get about another 200 by blowing off the landing gear.  Separating the 3 rear nukes takes our dV up to 7800+.

We're definitely close.  Obviously it's against the terms of the challenge, but if you actually filled the wings, strakes and nacelles with fuel (i left them empty), that's   another 2000 LF right there.

Feel free to borrow anything from this design you like,  I got MMO characters to level.  Good luck guys !  

 

[AeroGav]

Any suggestions on how my design can be optimised ?  Obviously, relegating Jeb to a chair is one thing.     Forgoing the mk3 engine mounts is another - but drag will increase a lot.  That means more jet engines, which do have a mass that must be accelerated to 1500m/s / 25km.    More to the point,  that horizontal, hypersonic cruising climb to orbit on NERV power might not be efficient with higher atmospheric drag.   Maybe try a zoom climb out of the atmosphere, and conduct the final acceleration from 1500 to orbital velocity above 60km and separate the aerodynamic parts before doing so?   However that means even more jet engines to get the necessary TWR.   If the zoom climb wasn't quite sufficient, the NERVs will suffer gravity losses thrusting upwards trying to keep us from falling back into the atmosphere.