How cheap are low-tech(panther) spaceplanes?

[Reusables]

2 hours ago, Wanderfound said:

Demonstrating possibilities:

  (snip)

 

This looks promising! How much cost does it spend? Also can it get to several biome at once?

[AeroGav]

16 minutes ago, Abastro said:

This looks promising! How much cost does it spend? Also can it get to several biome at once?

BTW, there's a thread in the challenge section where I flew this to Minmus.   Had about 400dV left over for driving over the surface.

I am now working on a "stretch" version of this craft to see if i can get to the Mun.

[GoSlash27]

I built a low tech Panther SSTO way back when it was new.

It was cheap enough, but the R&D time and difficulty involved in making it survive the trip back home made it not really worth the effort. The problem wasn't the Panther itself, but rather the other tech that was available at the time. The changes in the tech tree may have made it easier since then.

Best,
-Slashy

[Reusables]

14 minutes ago, AeroGav said:

BTW, there's a thread in the challenge section where I flew this to Minmus.   Had about 400dV left over for driving over the surface.

I am now working on a "stretch" version of this craft to see if i can get to the Mun.

Again, looks great! what is the (fuel) cost?

4 minutes ago, GoSlash27 said:

I built a low tech Panther SSTO way back when it was new.

It was cheap enough, but the R&D time and difficulty involved in making it survive the trip back home made it not really worth the effort. The problem wasn't the Panther itself, but rather the other tech that was available at the time. The changes in the tech tree may have made it easier since then.

Best,
-Slashy

Wow...  That series of spaceplanes for each tech looks gorgeous.

How much does the fuel cost?

[Wanderfound]

1 hour ago, Abastro said:

This looks promising! How much cost does it spend? Also can it get to several biome at once?

About 2,000 credits to fill the tanks.

Two biomes on Minmus are easy, three are possible if you push it. One is probably as many as you'll get on the Mun. Reentry is tricky; that Science Jr really isn't built for anything but a low orbit aerobrake.

Swap the Sci Jr for an inline docking port (or put a shielded port on the nose), add some drag chutes and refuel it in orbit and it'd make a good Duna ship.

It might be worth putting the Sci Jr and the contents of the service bay into an inline fairing.

Edited April 16, 2017 by Wanderfound

[AeroGav]

1 hour ago, Abastro said:

Again, looks great! what is the (fuel) cost?

 

OK here is the stretch version - I added three more LF tanks and quite a few extra wing parts.  It's more leisurely getting up to speed and i have to run the nukes a bit longer to get supersonic.   Weight is about 30T now.    

At the Mun, two nukes give >4:1 TWR.

It is difficult to clamber back in the cockpit.   Val gets stuck in a falling animation and slid the whole length of the fuselage between the side and main stack.  I reckon if i offset them outward a bit she won't get "stuck in the groove".

I moved the Vernor thruster up to the nose so i can pitch the nose up easier on takeoff.  Not necessary as it also has a reaction wheel, in fact i kept tail striking.   In the end i took off by pitching the nose up a little while stood still,  just below the tail strike angle, then locking that angle with SAS.    Apply full power and off we went. 

The longer nose and larger wings shield the cockpit even better from heat.

Wanted to see how slow it'd stall, the combo of Reaction Wheel and Vernor thruster let the nose go way up into a true stall if you keep pulling.    Val busts her tail off, literally as well as figuratively.

2488 Funds for the fuel used in the Mun mission.    

The non-stretched Auto Ray  costs 1632 funds to fill the tanks.

Early access for the Stretch Ray here - https://www.dropbox.com/s/t4uwzh5t6kqhaht/Stretch Ray.craft?dl=0

[Reusables]

Thanks for showing me your magnificent works!

Though, it seems that Panther spaceplanes won't worth it, as I can do it in competitive cost with reusable rockets.

 

Let's think about crew section with basic science experiments.

- Mk1 Crew pod + Mk16 Parachute + 1.25m Service Bay + Probodobodyne HECS + 3 x LT-1 Landing Strut: 1.25t.

- Science Jr. + Mystery Goo + Thermometer + Barometer + Accelerometer + Communotron 16-S + 2 x Solar Panel : 0.29t.

- Adding 2 Delta-Deluxe wings will grant it Shuttle-type reentry with 100% recovery. Let's say 0.16t.

So 1.7t in total.

 

For Minmus>

Attaching single FL-T400 & single Terrier to above gives wet mass of 4.45t and dry mass of 2.45t.

Dv budget : 2.02km/s, which should be capable of landing twice or several suborbital hops on minmus, and back to kerbin. (Suicide burn)

Cost: 4.45t * 380/t + 2t * 91.8/t = 1874.6

 

For Mun>

Attaching FL-T400 + FL-T200 + Oscar-B & single Terrier to above gives wet mass of 5.8t and dry mass of 2.6t.

Dv budget : 2.72km/s, which will be capable of mun landing once with suicide burn, and back to kerbin.

Cost: 5.8t * 380/t + 3.2t * 91.8/t = 2498

 

It will cost more in real applications, but it will be hard to design and fly Panther-based SSTO as well.

Also, for both cases, the TWR is obviously overpowered. It could be better & cheaper with 2 sparks. Moreover, Apollo-style landing is possible with this on Mun.

12 hours ago, Wanderfound said:

About 2,000 credits to fill the tanks.

Two biomes on Minmus are easy, three are possible if you push it. One is probably as many as you'll get on the Mun. Reentry is tricky; that Science Jr really isn't built for anything but a low orbit aerobrake.

Swap the Sci Jr for an inline docking port (or put a shielded port on the nose), add some drag chutes and refuel it in orbit and it'd make a good Duna ship.

It might be worth putting the Sci Jr and the contents of the service bay into an inline fairing.

Is it really capable of Mun landing? It costs significantly more dv to do so. Then I should take a look on this one.

11 hours ago, AeroGav said:

 

OK here is the stretch version - I added three more LF tanks and quite a few extra wing parts.  It's more leisurely getting up to speed and i have to run the nukes a bit longer to get supersonic.   Weight is about 30T now.    

At the Mun, two nukes give >4:1 TWR.

It is difficult to clamber back in the cockpit.   Val gets stuck in a falling animation and slid the whole length of the fuselage between the side and main stack.  I reckon if i offset them outward a bit she won't get "stuck in the groove".

I moved the Vernor thruster up to the nose so i can pitch the nose up easier on takeoff.  Not necessary as it also has a reaction wheel, in fact i kept tail striking.   In the end i took off by pitching the nose up a little while stood still,  just below the tail strike angle, then locking that angle with SAS.    Apply full power and off we went. 

The longer nose and larger wings shield the cockpit even better from heat.

Wanted to see how slow it'd stall, the combo of Reaction Wheel and Vernor thruster let the nose go way up into a true stall if you keep pulling.    Val busts her tail off, literally as well as figuratively.

2488 Funds for the fuel used in the Mun mission.    

The non-stretched Auto Ray  costs 1632 funds to fill the tanks.

Early access for the Stretch Ray here - https://www.dropbox.com/s/t4uwzh5t6kqhaht/Stretch Ray.craft?dl=0

I should say that I like this one. Also it's cheaper than the figure I got with reusable rockets.

But it's hard to use, I think...

[Wanderfound]

2 hours ago, Abastro said:

Is it really capable of Mun landing? It costs significantly more dv to do so. Then I should take a look on this one.

1,000m/s in the tanks when it lands on Minmus, and more than enough TWR for the Mun (especially if you save a little oxidiser for emergency landing boost). Land just uphill of a biome boundary and you can roll over for a second science grab.

PITA to reenter without cooking the Science Jr, though. I worked out the reentry handling issue, BTW; the rudder was still set to influence roll and pitch.

Edited April 17, 2017 by Wanderfound

[Reusables]

1 hour ago, Wanderfound said:

1,000m/s in the tanks when it lands on Minmus, and more than enough TWR for the Mun (especially if you save a little oxidiser for emergency landing boost).

Well, mun is much harder than minmus...

According to the dv map here:http://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet, Minmus landing takes 1270m/s while Mun landing and back takes 2630m/s. Even minmus landing and back only takes 1610m/s, so 1km/s more on minmus won't cut it...

Edited April 17, 2017 by Reusables

[AeroGav]

4 hours ago, Abastro said:

But it's hard to use, I think...

Probably highly subjective.   I've never flown a boostback rocket and the idea scares me,  i find gravity turning a normal rocket takes multiple tries to get right, and every time i change the design of the rocket i have to learn all over again.  Both aircraft I designed to fly on prograde lock within the atmosphere.  Action group 1 raises the nose a couple of degrees, action group 3 lowers the nose a couple of degrees, action group 2 is neutral trim.    Just a case of waiting.

Edited April 17, 2017 by AeroGav

[Reusables]

1 hour ago, AeroGav said:

Probably highly subjective.   I've never flown a boostback rocket and the idea scares me,  i find gravity turning a normal rocket takes multiple tries to get right, and every time i change the design of the rocket i have to learn all over again.  Both aircraft I designed to fly on prograde lock within the atmosphere.  Action group 1 raises the nose a couple of degrees, action group 3 lowers the nose a couple of degrees, action group 2 is neutral trim.    Just a case of waiting.

I never boostback, as it's more expensive for Kerbals. It's just matter of timing, with a bit of thrill for such a relaxing game.

And gravity turn is generous. Again, it's just matter of timing(Turn starting speed). Error of 5m/s is fine for this.

Also it's possible to correct a turn before the transonic region. (Remember that any part has a lift now)

[Wanderfound]

2 hours ago, Abastro said:

Well, mun is much harder than minmus...

According to the dv map here:http://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet, Minmus landing takes 1270m/s while Mun landing and back takes 2630m/s. Even minmus landing and back only takes 1610m/s, so 1km/s more on minmus won't cut it...

Try this version:

 

Craft file at https://www.dropbox.com/s/7ha864hb7iidm8o/Minmus Panther C%2B.craft?dl=0

Requires a bit of piloting precision for maximum fuel efficiency, but could do Minmus even if flown a bit roughly. Flight cost is up to 7,000 due to the droptanks, though.

Edited April 17, 2017 by Wanderfound

[Reusables]

16 minutes ago, Wanderfound said:

Craft file at https://www.dropbox.com/s/7ha864hb7iidm8o/Minmus Panther C%2B.craft?dl=0

Requires a bit of piloting precision for maximum fuel efficiency, but could do Minmus even if flown a bit roughly.

I like it, but it seems that it costs more than the fuel cost of my Aleph lander which carries a miniature rover in it.

I know, precision landing is impossible with this one, in the case I can add some wings.

It's definitely overpowered:

 

[GoSlash27]

20 hours ago, Abastro said:

Again, looks great! what is the (fuel) cost?

Wow...  That series of spaceplanes for each tech looks gorgeous.

How much does the fuel cost?

Abastro,

 It's been so long that I don't remember, but that's not what's important.

Fuel cost is pretty trivial no matter which way you go. The early Panther SSTOs are workable, but the lack of associated spaceplane tech makes them unattractive at best and catastrophic at worst. If you have just one break up on reentry, it wipes out any fuel savings you might have seen. Plus, spaceplanes are really for the mundane " milk run" missions that you have to do frequently. They don't really have a role at that stage in the career to justify the R&D effort.
 My advice is to wait until having a spaceplane is actually an advantage. By that time, you'll have better options.

My $0.02,
-Slashy

[AeroGav]

Can you link one of your TSTO re-usables?   Do you launch vertical only, or do a "once around" suborbital flight on the lower stage?

Getting the Whiplash won't make much difference to spaceplane economics for missions to minmus etc. because another 300 or so airbreathing velocity won't help much when the entire mission consumes loads of delta V.  If you're only going to LKO with cargo , makes a bigger difference.

However, that hypersonic tech also gives you the aerospike engine.   Have you seen the ISP it gets atmo and vacuum?  Got to be a huge improvement on whatever you're using now for a re-usable booster.

[Reusables]

1 hour ago, AeroGav said:

Can you link one of your TSTO re-usables?   Do you launch vertical only, or do a "once around" suborbital flight on the lower stage?

I'll upload the craft file, with some launch instructions. It's just TSTO rocket, with both stage are reused via parachutes.

1 hour ago, AeroGav said:

Getting the Whiplash won't make much difference to spaceplane economics for missions to minmus etc. because another 300 or so airbreathing velocity won't help much when the entire mission consumes loads of delta V.  If you're only going to LKO with cargo , makes a bigger difference

I think staged lander design is more efficient than SSTM which should haul the whole plane which is pretty heavier. And LKO with compact cargo becomes reasonable choice with Whiplash, this makes the difference. Also fuel/crew transport to LKO should be much more efficient as well.

1 hour ago, AeroGav said:

However, that hypersonic tech also gives you the aerospike engine.   Have you seen the ISP it gets atmo and vacuum?  Got to be a huge improvement on whatever you're using now for a re-usable booster.

I once though it's great engine, but it didn't take me much time to realize that it's niche engine for eve & spaceplanes.

As an atmospheric engine, it loses to Reliant. It has greater ISP, but it's much more expensive. Even with 98% recovery, you lose 77 per engine! And I typically get 94~96%. As its atmospheric thrust is only 154kN, it has hard time lifting 1.6t of payload per engine. (While Reliant loses 22 per engine and can lift 2t~2.5t)

As a vacuum engine, it loses to Poodle. 10s of ISP gain means less fuel consumption. Single Aerospike as a vacuum engine only has a meaning when it can lift 10t of payload,  A Poodle is only 0.75t heavier than an Aerospike, which is dwarfed by payload mass (typically near 10t for its thrust)

It's a bit better than Terrier, but the gain is not so much.

2 hours ago, GoSlash27 said:

Abastro,

 It's been so long that I don't remember, but that's not what's important.

Fuel cost is pretty trivial no matter which way you go. The early Panther SSTOs are workable, but the lack of associated spaceplane tech makes them unattractive at best and catastrophic at worst. If you have just one break up on reentry, it wipes out any fuel savings you might have seen. Plus, spaceplanes are really for the mundane " milk run" missions that you have to do frequently. They don't really have a role at that stage in the career to justify the R&D effort.
 My advice is to wait until having a spaceplane is actually an advantage. By that time, you'll have better options.

My $0.02,
-Slashy

Thanks! I'll unlock those spaceplane nodes after gravioli & refinery.

[AeroGav]

9 minutes ago, Abastro said:

I once though it's great engine, but it didn't take me much time to realize that it's niche engine for eve & spaceplanes.

As an atmospheric engine, it loses to Reliant. It has greater ISP, but it's much more expensive. Even with 98% recovery, you lose 77 per engine! And I typically get 94~96%. As its atmospheric thrust is only 154kN, it has hard time lifting 1.6t of payload per engine. (While Reliant loses 22 per engine and can lift 2t~2.5t)

As a vacuum engine, it loses to Poodle. 10s of ISP gain means less fuel consumption. Single Aerospike as a vacuum engine only has a meaning when it can lift 10t of payload,  A Poodle is only 0.75t heavier than an Aerospike, which is dwarfed by payload mass (typically near 10t for its thrust)

It's a bit better than Terrier, but the gain is not so much.

Surely a re-usable first stage will be flying above 10km though, where it's vacuum isp is WAAY better than on the Reliant?

Not really a rockets person though so i wouldn't know

[Reusables]

21 minutes ago, AeroGav said:

Surely a re-usable first stage will be flying above 10km though, where it's vacuum isp is WAAY better than on the Reliant?

It's ISP is always better than Reliant. The problem is its cost.

[AeroGav]

2 hours ago, Abastro said:

I'll upload the craft file, with some launch instructions. It's just TSTO rocket, with both stage are reused via parachutes.

I'd be interested to see how a properly constructed rocket flies.  Maybe it's just practice or maybe my rockets tend to have poor handling.

[Spricigo]

3 hours ago, Abastro said:

I once though it's great engine, but it didn't take me much time to realize that it's niche engine for eve & spaceplanes.

QFT. Even then quickly become less useful once you have access to Nerv and RAPIER.

So far I think you made the case for recoverable rockets. Have you considered TSTO spaceplanes/air launch to orbit, using drop tanks with stage recovery or using FMRS?

 

10 hours ago, AeroGav said:

I find gravity turning a normal rocket takes multiple tries to get right, and every time I change the design of the rocket I have to learn all over again.

Actually is not that different than relearning to flight a slight different spaceplane while is true that initial condition make much more difference for gravity  turn. What I do its to design my launch vehicles to lift a standard payload mass/size, and try to design my payloads with that size/mass. Often a smaller payload can be used for the 'rounding'. e.g adding a half ton satellite to a 4t payload to get closer to the 5t the LV is designed for.

Another point its that slight differences in a rocket usually just requires slight differences in the initial angle/thrust or how long until you adjust SAS setting.* It may seem complex but once you get used its not difficult to judge which adjustment is needed.

Anyway, I think that its enough out of topic. Maybe we can discuss it in another thread.

 

*disclaimer:

        A) I design my LV so my launch procedure is 1.launch 2. set SAS to prograde(or turn off) at a given speed or height  3.circularize at apoapsis. Maybe use the WASD keys when circularizing (doing it less and less often) but not before. Staging is handled by smart parts.

        B) playing in normal setting (which is what I do) allows for less than optimal LV cost wise, a few extra funds for some convenience is a fair price. In particular SRBs in first stage may be(and often are) tuned for better control at cost of efficiency.

       C) Like spaceplanes, rockets also have flight profiles. "reach 45° at 10 Km" is a common rule of thumb (but don't fit every single rocket out there). Also like spaceplanes abrupt change of directions are usually counterproductive. If you are fighting the rocket something is wrong.

    

[Reusables]

On 2017. 4. 18. at 5:09 AM, Spricigo said:

QFT. Even then quickly become less useful once you have access to Nerv and RAPIER.

So far I think you made the case for recoverable rockets. Have you considered TSTO spaceplanes/air launch to orbit, using drop tanks with stage recovery or using FMRS?

I don't like Stage Recovery & FMRS. They looks too overpowered to me.

 

@AeroGav, here are my lifters: https://www.dropbox.com/sh/13b2rchjw8hioeh/AAC6VwTb2nF4ZC4MUb5P_Ioba?dl=0

Generally, turn rocket 5 degrees around 60m/s works for my reusable rockets. The speed may vary per lifter. Hold to prograde after that.

(Start the pitchover 10m/s earlier than the speed, pitching 5 degrees is sometimes not so easy)

It doesn't like payloads far from aerodynamic shape, like ones with blunt edges.

 

If ship description persists, there will be flight instructions. In case it's lost:

The first stage would have to reach 100m/s with 5deg pitch, and should reach 340m/s with 70 deg pitch. Just before separation it must reach 60deg pitch. (near 700m/s)
After the first stage separation, set pitch to 45 degrees and raise apoapsis to 90km~100km  85~90km, and burn horizontally after that. This is to give the first stage time to fall. Burn till the first stage reaches 26km. Set throttle to zero and switch to the first stage just after that. (On the map view)
The first stage will fall rapidly, and parachute will slow it down just before hitting the water. Switch to the second stage at the very moment it gets under 1m/s.
After that, gain lateral speed with pitch on 10~15deg. This is to prevent falling to the atmosphere.

 

It should be similar with this one:

 

My 5t lifter is not finished(I thought bicoupler is not visual), but one may be able to lift both mun/minmus lander at once with modified 10t lifter. Spark instead of Terrier will shave some weight for that.

EDIT: I had a issue here; Those won't form orbit as high as 100km Ap.;

Edited April 25, 2017 by Reusables

[Spricigo]

 

I download it read the instruction and tried to use it. So far I have to say it requires some skill I seem to lack. Each time I either failed to recover the first stage before it vanished or to reach orbit (and once I managed to fail in both )

Was an intersting experice but I have no qualms about FMRS and normal difficult, so Im going back to my Fire&Forget Expendable LV. Maybe I try it again later.

 

[Reusables]

Welp.  I didn't know that I have some skills.

I think ll2 is slightly bugged, it might be the problem.

(Also it may be better to burn till Ap is on 85km and hold pitch to 10deg till 90km)

[Wanderfound]

Another option:

 

https://www.dropbox.com/s/eqreh7jzae53mln/Minmus Panther D.craft?dl=0

[Reusables]

Refueling? Ingenious! So you can reuse the whole plane over and over? I should have opened Panther!