Tech level 7 SSTO to Minmus surface and back

[ManEatingApe]

Finding the right ratio of Panther/Nuke is certainly an interesting problem!

I feel 2:1 Panther/Nuke is the most effective. 2:2 means you're carrying an extra 3 ton heavy nuke, I'd much rather have an extra 3 tons of fuel.

1:1 is essentially the same as 2:2 but much harder to design due to the asymmetry.

 

A stretched version of my original entry is able to make LKO with between 3000 ~ 3100 m/s dV (depending on piloting skill ) enough to make it to the Mun and back with some to spare.

Edited April 16, 2017 by ManEatingApe

[Wanderfound]

 

Craft at https://www.dropbox.com/s/zvxr4sfacamxgb1/Minmus Panther C.craft?dl=0

To be honest, it's a touch flippy on reentry. Move the wings back a bit if you want to use it.

Edited April 16, 2017 by Wanderfound

[AeroGav]

13 hours ago, ManEatingApe said:

Finding the right ratio of Panther/Nuke is certainly an interesting problem!

I feel 2:1 Panther/Nuke is the most effective. 2:2 means you're carrying an extra 3 ton heavy nuke, I'd much rather have an extra 3 tons of fuel.

1:1 is essentially the same as 2:2 but much harder to design due to the asymmetry.

 

I spent about an hour trying to build a panther/terrier/nerv , but it made my head hurt and i've run out of milk for coffee.  I am sure at some scale this is the best power plant but fitting all those engines in the right ratio into mk1 ship is hard.  Honestly, a methodical rocket guy type person, working backwards from mun delta v , could probably figure this out with a spreadsheet.   @GoSlash27 , over to you !

So,  I just stretched the Voodoo Ray.

I added three more mk1 liquid fuel tanks to get the delta v,  and a significant amount of extra wing parts to lift it all,  and kept the same  1 panther 2 nerv layout.

Check out that supersonic Lift/Drag ratio - 4.237 to 1 - Woof !

Val is about to learn about tailstrikes.    Oh well it's not like nukes cost much if you smash them, i'm sure it won't contaminate the environment or anything.

https://www.dropbox.com/s/t4uwzh5t6kqhaht/Stretch Ray.craft?dl=0

If you can use LF/O propellant to get from 750 m/s to 1550 , orbital freefall is supporting us and one nuke could push us the whole way.

The problem is, that's quite some boost it'lll need off the chem propulsion, will the mass of LFO + terrier/spark weigh more than you saved with only 1 nuke?  Well, the upside is by 1550 m/s all that heavy LFO will be gone and you'll only be dragging the tiny weight of LFO engine (s) up to the moon instead of a heavy second nuke.    But,  this extra takeoff weight may mean you need to go to 2 panther engines , so that's an extra panther you're dragging the whole way and back.

[GoSlash27]

10 hours ago, AeroGav said:

Honestly, a methodical rocket guy type person, working backwards from mun delta v , could probably figure this out with a spreadsheet.   @GoSlash27 , over to you !

AeroGav,

I'm afraid I'm the wrong guy to ask about this problem. I never design spaceplanes to go any further than LKO since airplanes make such lousy spacecraft. I can say that nukes are worth it from a mass perspective if the total vacuum DV is greater than 2 km/sec, and not worth it for smaller jobs.

 Since the Mun requires a lot more DV than 2 km/sec DV, I'd skip the Terrier entirely and just go Panther/NERV.

 I have done LF SSTOs in the past. My designs were based on the notion that vacuum engine thrust should be 1/2 of the air breathing thrust at Mach 1, so 2 nukes per Panther.

HTHs,
-Slashy

[pacovf]

PPE 1

 

@Wanderfound: Nice! I also really like the design of your craft  Adding you to the OP

@AeroGav: if you didn't use big S parts, that satisfies the conditions of the challenge. Can you tell me how heavy the craft was? Also, I assume a single landing on the Mun. Did you get any extra science, aside from the trifecta Crew Report / EVA report / surface sample?

 

If you want some numbers, you might want to use this plot. It shows how much liquid fuel you need to carry into orbit if you want to have the delta v specified in the legend, depending on the dry mass of your craft.

A few numbers to help out:

Payload: 

• Mk1 Inline cockpit: 1.0t
• Mk1 Command pod: 0.8t
• Science Junior: 0.2t
• Mystery Goo: 0.05t
• Service Bay (1.25m): 0.1t

Engines:

• NERV: 3t
• Panther: 1.2t
• Terrier: 0.5t
• Spark: 0.1t

Fuel:

• FL-T400: 2.25t full, with 2t of LF/O and 0.25t of container (other LF/O containers follow the same ratio)
• Mk1 Liquid Fuel Fuselage: 2.25t full, , with 2t of liquid fuel and 0.25t of container (Mk0 has a marginally better ratio, NCS Adapter considerably worse)

Lift/control:

• 1 unit of lift area: 0.1t
• 1 unit of control area: 0.2t
• Advanced Inline Stabilizer: 0.1t

 

 

 

On April 15, 2017 at 9:20 PM, ManEatingApe said:

Finding the right ratio of Panther/Nuke is certainly an interesting problem!

I feel 2:1 Panther/Nuke is the most effective. 2:2 means you're carrying an extra 3 ton heavy nuke, I'd much rather have an extra 3 tons of fuel.

1:1 is essentially the same as 2:2 but much harder to design due to the asymmetry.

 

A stretched version of my original entry is able to make LKO with between 3000 ~ 3100 m/s dV (depending on piloting skill ) enough to make it to the Mun and back with some to spare.

 

If you land it on the Mun and get it back, I will add you to the OP  Main question is whether you can actually land it on the Mun and then get it off there again, considering the low thrust of the NERV.

[AeroGav]

4 hours ago, pacovf said:

If you land it on the Mun and get it back, I will add you to the OP  Main question is whether you can actually land it on the Mun and then get it off there again, considering the low thrust of the NERV.

Surely not in doubt?  The Stretch Ray has a takeoff weight of 30T, has 4:1 TWR on the Mun with dual nukes - obviously by the time it reaches the Mun it will have lost a lot of fuel mass, and Mun has low gravity.      His ship might have half the nuke engines but unless it also has twice the mass it will be fine.    So long as it has the delta V it can do it.

My Stretch NERV is 30T takeoff, i did these designs in Sandbox so i can't tell what science you can get, I just limited myself to lowtech parts.

On Minmus you can drive over the surface to multiple biomes using very little fuel.    You can put small science instruments in the service bay.    On the Mun, hillier terrain, greater distances, higher losses from climbing the hills due to gravity make surface roving not worth the effort.

I suppose you could try putting a science junior on the ship but i'd say it's risky.  The launch profile has it flying long and fast in the atmosphere, it might blow up, detaching something critical.   Fuel tanks or engines in the same stack as this component would get moved significantly fore or aft due to its length, so i'd have to adjust the handling again.

I really don't think you need to though.  Consider the minmus mission -

Crew Report, EVA Report, Surface Sample, Temperature,  Pressure Scan from every biome.  You land on the flats and drive north to the polar region then takeoff and fly home.  So that's 5 biomes.    That is enough science to unlock Whiplash and Probably RAPIER.

[AeroGav]

Its kind of funny how much fatter my designs look compared with everyone else's

Edited April 17, 2017 by AeroGav

[ManEatingApe]

12 hours ago, pacovf said:

If you land it on the Mun and get it back, I will add you to the OP  Main question is whether you can actually land it on the Mun and then get it off there again, considering the low thrust of the NERV.

No worries, will this do? 

 

Same simple ascent profile as before, point nose at 17.5° initially then leave it. Stage the sparks and nukes at maximum air breathing speed.

Keep the nose pointing up until LF/O is exhausted, then lower nose slowly so that we "surf" just behind AP until orbit

60 kN of thrust from the nuke versus of craft mass of 13 tons gives a Mun TWR of over 2.5 making a regular landing straightforward...as we have some fuel to spare so let's see if we can liven things up a little.

I hope we remembered to set the parking brake...

To take off Bob had to perform the world's trickiest 3 point turn - those driving lessons paid off handsomely!

Many many aero-braking passes later, back at KSC

502 science / 21.385 tons on runway  = a score of 23.5

Full Album

Link to Craft file

 

@AeroGav Your designs aren't fat - they're curvaceous!  Seriously though, I'm impressed how much you can get to orbit with such a low TWR

Edited April 17, 2017 by ManEatingApe

[AeroGav]

On 16/04/2017 at 10:47 AM, Wanderfound said:

 

Craft at https://www.dropbox.com/s/zvxr4sfacamxgb1/Minmus Panther C.craft?dl=0

To be honest, it's a touch flippy on reentry. Move the wings back a bit if you want to use it.

Wanderfound, I really like the look of that ship,  I had a bit of a play with it to see if i could reduce drag and therefore the amount of engines.

I put reversed cones on the rear attach nodes of the rocket engines, to remove the drag of the unused attach nodes, and angled the wings and canards with 5 degrees of incidence.  I also got rid of the mk0 fuel tanks, they have quite a poor capacity to drag ratio (nearly as bad as mk2).    The Oscar Bs OTOH, have one third the drag and nearly as much capacity and are just stonking, however  after the cleanup it didn't need so much LFO anyway.  

Ft800 tank > swapped for two more mk1 lf tanks

mk 0 tanks > deleted

Oscar b tip tanks > removed 3 from each wing

Sparks > only two now fitted

Flight profile - fly with SAS off and let it do its own thing up to about 7/8km.  As airspeed passes 260 km, action group 3 for nukes, SAS on set to prograde hold.   At mach 1.3,  toggle nukes off again.    It will bob up and down a bit, zooming over 14km once or twice.  Once it bounces back up at 12km + and 750 m/s +, start the nuke.   At 18km, start the sparks.

Cockpit overheated with this method,  it's closer to the front than in mine, also smaller wings - climbs slower.   I've put the service bay ahead of the cockpit and a heatshield with a small amount of ablator ahead of it, hopefully will stop it heat soaking.

https://www.dropbox.com/s/aysgzf8b29i5k92/Minmus Panther C gav.craft?dl=0

[pacovf]

12 hours ago, AeroGav said:

Surely not in doubt?  The Stretch Ray has a takeoff weight of 30T, has 4:1 TWR on the Mun with dual nukes - obviously by the time it reaches the Mun it will have lost a lot of fuel mass, and Mun has low gravity. His ship might have half the nuke engines but unless it also has twice the mass it will be fine.    So long as it has the delta V it can do it.

Not in doubt, but the terms of the challenge are what they are. I am ok with being lax on other things, but I have to draw the line somewhere...

12 hours ago, AeroGav said:

My Stretch NERV is 30T takeoff, i did these designs in Sandbox so i can't tell what science you can get, I just limited myself to lowtech parts.

If you tell me what science instruments you had on it, we can figure out the science you would have gotten, and give a score to your craft

12 hours ago, AeroGav said:

I really don't think you need to though.  Consider the minmus mission -

Crew Report, EVA Report, Surface Sample, Temperature,  Pressure Scan from every biome.  You land on the flats and drive north to the polar region then takeoff and fly home.  So that's 5 biomes.    That is enough science to unlock Whiplash and Probably RAPIER.

Well, if you already have access to the parts required to fulfill this challenge, you've probably already gotten most easy science from Minmus.  Don't overthink things too much, the challenge is loosely based on Career mode, but with extra "unrealistic" constraints to make it more difficult/fun, and maybe learn a thing or two about Spaceplanes, Panthers, and flight profiles.

 

@ManEatingApe: That was absolutely awesome and I wish I had added a style points clause to the score. Adding you to the Hall of Champions OP.

[Cunjo Carl]

Yay! I've been distracted by Stardew Valley for a while, but I had some ideas that just wouldn't sit still, so I made a rocket with them. Much to my disbelief, they worked!

I finally worked the asymmetry to it's logical conclusion with this peculiar panther SSTO, which uses only 1 each of the panther, terrier and NERV. When it comes to maximizing deltaV with these engines, the fewer we can get away with the better! Only one of each was a bit of a stretch. I tried models that swapped the terriers for sparks or twitches, but the ISP loss was just a bit too nasty, and the deltaV advantages of the lower dry mass just weren't there with that 3 ton NERV needing to get lugged around. The single Panther is a hallmark of this design series, and demands a significant wing area to make up for the lack of thrust in air breathing mode. Because of some drag optimizations in this model though, it gets by well enough.

Drag was reduced significantly from the earlier design by removing a terrier, putting all the oxidizer into Oscar Bs (which just had a huge v1.2 drag reduction), and putting a side-drag smoothing faring on the NERV. Because of insane novel way the Panther is placed, it's not any easier to breakthrough the sound barrier than before- the plane still requires a break in the ascent to focus on gaining speed. But, the lower drag becomes much more apparent during the Terrier+NERV portion of the burn.

So is it all worth it, compared to more traditional designs? Nah. .  It's still a huge improvement over my earlier Mun shot with probably 600-800m/s extra. It could even be enough for an extra suborbital hop!

 

But for now, it's time to jump back to watering the cows and feeding the plants in Stardew Valley- Be back soon!

 

 

 

Oh, and @ManEatingApe, huge props on landing on the arch! Also, @AeroGav, I've been noticing you use NCS Adaptor + small cones pretty often. Are they superior to the standard cones in performance, or just in looks?

[AeroGav]

22 minutes ago, Cunjo Carl said:

I've been noticing you use NCS Adaptor + small cones pretty often. Are they superior to the standard cones in performance, or just in looks?

More heat resistant than standard cone, negligible extra drag - plus it puts more parts between cockpit and heat, so i use it for the main stack.  Engine nacelles sit further back so no need

[ManEatingApe]

13 hours ago, Cunjo Carl said:

It's still a huge improvement over my earlier Mun shot with probably 600-800m/s extra. It could even be enough for an extra suborbital hop!

If you're careful you could manage a round trip to Duna for about 3,200 m/s, just sayin'... 

[pacovf]

That's awesome. The way you placed the Panther to avoid roasting the Terrier stack is also really cool. Did the side fairing really help? 

Do you want a score to go with that? Since you already landed a similar design on the Mun, if you give me the mass of the craft, I will put you in the OP. But if you want to land it twice, I will need pics

[Cunjo Carl]

2 hours ago, pacovf said:

That's awesome. The way you placed the Panther to avoid roasting the Terrier stack is also really cool. Did the side fairing really help? 

Do you want a score to go with that? Since you already landed a similar design on the Mun, if you give me the mass of the craft, I will put you in the OP. But if you want to land it twice, I will need pics

Thanks! No score for this yet, please. I'll do another few rounds of design (adding sci bays) drag optimization and the dreaded reentry test before sending it off to the Mun.... or Duna. I totally wanna do Duna now! It has a wet mass of 30 tons, so it's definitely a heavyweight.

The side fairings really do help, though my tiny amount of experimentation with them a couple versions back suggested they wouldn't be worth the weight on most normal rockets. This is a fairly special case though where the drymass is unavoidably high (so the added mass doesn't matter), and the TWR is quite low (so the drag really matters). I'll be honest, I don't know the mechanism for how it works... those fairings can be funny.

I've just realized, that in my old experiments I never considered blowing off the fairing once I got to space... I should try that on a non-SSTO craft some time!

[AeroGav]

5 hours ago, Cunjo Carl said:

I totally wanna do Duna now! It has a wet mass of 30 tons, so it's definitely a heavyweight.

Put 2 or 3 downward firing Vernor engines in the belly, save an Oscar B tankfulll of  LFO the landing, you can reduce your landing speed to 50 m/s or so with the lift engines.      That's the only fuel you'll use after setting up the encounter with Duna because aerobraking and gliding approach will do the rest.    Should definitely be able to hit multiple biomes

[AeroGav]

Well,  I got round to flying a Duna mission on mine.    Beefed up the landing gear, added two Vernors, and 3 oscar Bs.   Each landing used about 10 units of oxidizer.    

Some stunning vistas,  but sadly we only had enough delta V to land at a couple places then fly to duna orbit.    I used a 130km parking orbit on kerbin which isn't efficient ( direct burn from launch is best if you take a few tries to get launch timing right).   But perhaps we're expecting too much from this level of tech to make a single stage round trip.

What i would do, is find some way to refuel this plane so it can do Duna properly - it has enough oxidizer for 6 horizontal landings, with only a little extra fuel it could have done all that and come home.     Easiest way is probably to put a junior clamp o tron on the nose  and have two of these airplanes meet in low orbit, have one give its fuel to the other.   Can always wear  a small nose cone to cover the clamp o tron on the way up, to save drag and stop it melting, then decouple it.

It can fly around on kerbin on dry power, so if you're ambitious you'd brim the tanks in orbit and send it to Laythe - could probably visit every island.

[pacovf]

Man, that's insane. Those landings were really scary too. To think that I originally posted that landing on the Mun and going back might not actually be possible...

[Wanderfound]

On 26 April 2017 at 11:17 AM, pacovf said:

Man, that's insane. Those landings were really scary too. To think that I originally posted that landing on the Mun and going back might not actually be possible...

Especially on Duna, drag chutes are your friend:

They allow you to keep your airspeed above stall while still coming to a rapid stop post-touchdown.

[pacovf]

Wouldn't airbrakes be more practical, if you are going that way?

[Wanderfound]

51 minutes ago, pacovf said:

Wouldn't airbrakes be more practical, if you are going that way?

Airbrakes can be handy for reducing speed while flying without needing to pull G's, but they'd contribute very little to post-touchdown deceleration. You want the plane stopped ASAP after touchdown, to minimise the risk of hitting a bump and losing a wingtip or somesuch.

My Duna ships are normally two-seaters: one scientist to reset experiments, one engineer to repack parachutes and a probe core in the cargo bay to handle the piloting duties.

[AeroGav]

The main thing I learned between my first two crash landings and the second two that were without damage, was that you need to have the wings level with respect to the slope on the ground at touchdown.    On my third landing attempt, the ground was sloping left to right so i had to bank 15 degrees to right to make both main gears touch down at same time.    If the mains dont touch down together, then the ground contact sets up a rolling torque that's propertional to your vertical descent rate on touchdown and as you can see from the first one, it can be pretty severe.

It's quite rare for things to go wrong once the wheels are solidly on the ground - i don't remember it happening, but a bounced landing, when you are still above flying speed, can get hairy.

[Aerospacer]

Wow, I didn't know about this challenge before..

So, here my SSTO and flight to Minmus for science:

One panther, no nuke, tech level=science160.

Launch mass 18.88t, science earned = 575.5.

[pacovf]

Well, I didn't think it would be possible to get anywhere without Nukes, but I guess I was proved wrong once more

Added you to the OP!