Spaceplane Carrier to Duna (Looking for constructive criticism and tips)

[Edax]

I'm about to attempt my first mission to Duna, and I've built a Spaceplane Carrier to get my spaceplanes to Duna and Ike to collect science. Since I've never attempted anything like this before, I was wonder if there's any oversights or flaws in this Spaceplane Carrier that could doom the mission, any thoughts?

The front end of the ship (the orange tank with the mailsail engine) will be left behind as a refueling station for Kerbin, while the back two-thirds will head off to Duna powered by a Poodle engine. One spaceplane is for Duna, and the other Ike, and this will be a two-kerbal mission. The flight plan is essentially to launch at the prime launch window for Duna, put in an orbit, have Valentina fly the spaceplanes one at a time, gather rocks and data, return to the vessel. After the missions are complete, she will then fly back to Kerbin in the Spaceplane with the LV-N while Jagie will say behind and conduct research in the on-board laboratory.

(Remember, I've never left Kerbin's gravity well, so I'm not entirely sure what to expect)

Edit:

The results of my trip:

Edited July 21, 2015 by Edax

[Jimbimbibble]

I see two potential issues. First, Ike has no atmosphere so a spaceplane is not going to help much. A regular lander would be better. Second, your ship will not be able to aerobrake very well because it will wobble too much. Make sure you pack enough fuel for a powered capture.

[Yemo]

It looks cool, though for a first interplanetary mission, I d recommend going minimal first.

So (small) probes before kerbals to scout out the destinations and test basic concepts for those bodies.

Like a lander for Ike (no atmosphere) and what works on Duna (the atmosphere has no oxygen, so jets do not work, but eg electric probs from USI Exploration or KAX will).

Do it more like a real space program, unmanned and minimal first.

Edited July 5, 2015 by Yemo

[Reddeyfish]

Jet engines won't work outside of the Kerbin and Laythe atmospheres. The engines on those planes are going to be worthless.

[windows_x_seven]

Your main concern here will be delta-v and thrust to weight ratios. The main ship should have enough delta-v to transfer itself and the planes to Duna and come back. The planes need to have a thrust to weight ratio higher than 1 (although you're going to want something equal or above 1.2) on Duna (2.94 m/s^2) and enough delta-v to land, go back to orbit and rendezvous. Note how jet engines won't work on any planets except Laythe and Kerbin, so choose engines that have a decent specific impulse in both atmosphere and vacuum (I see you chose the toroidal aerospike). One thing that I've noted, though, is that you don't have a escape pod. I recommend getting a capsule with a heatshield and enough fuel to deorbit from Kerbin orbit docked to that ship, in case things go south or if you want to be careful about re-entry, mostly because of fuel imbalances that make the craft unflyable.

[Edax]

Jet engines won't work outside of the Kerbin and Laythe atmospheres. The engines on those planes are going to be worthless.

Those jet engines are for returning to KSC.

Your main concern here will be delta-v and thrust to weight ratios. The main ship should have enough delta-v to transfer itself and the planes to Duna and come back. The planes need to have a thrust to weight ratio higher than 1 (although you're going to want something equal or above 1.2) on Duna (2.94 m/s^2) and enough delta-v to land, go back to orbit and rendezvous. Note how jet engines won't work on any planets except Laythe and Kerbin, so choose engines that have a decent specific impulse in both atmosphere and vacuum (I see you chose the toroidal aerospike). One thing that I've noted, though, is that you don't have a escape pod. I recommend getting a capsule with a heatshield and enough fuel to deorbit from Kerbin orbit docked to that ship, in case things go south or if you want to be careful about re-entry, mostly because of fuel imbalances that make the craft unflyable.

The first spaceplane, I call Valkyria III (which has the LV-N) has 3939 Delta V with a full tank, and has already landed on the mun and Minmus several times and returned home. The second spaceplane, the Diabolus X has 2507 Delta V with the toroidal aerospike and is meant for Duna (is that enough Delta V to land and return?) Admittedly the jet engines are a bit of dead weight, but it is an SSTO that docked to the Carrier under it's own power and I only plan to reuse them for reentry. The spaceplanes both can function as escape pods, and I regularly dock mk1 pods with heatshields to transfer crew between the ground and the carrier.

I also have no idea how to calculate TWR.

I should also note that I'm trying to land on every planet and moon with spaceplanes, so that's a personal challenge I set for myself.

- - - Updated - - -

It looks cool, though for a first interplanetary mission, I d recommend going minimal first.

So (small) probes before kerbals to scout out the destinations and test basic concepts for those bodies.

Like a lander for Ike (no atmosphere) and what works on Duna (the atmosphere has no oxygen, so jets do not work, but eg electric probs from USI Exploration or KAX will).

Do it more like a real space program, unmanned and minimal first.

Good point, I forgot to pack probes onto the ship.

Edited July 5, 2015 by Edax

[windows_x_seven]

The first spaceplane, I call Valkyria III (which has the LV-N) has 3939 Delta V with a full tank, and has already landed on the mun and Minmus several times and returned home. The second spaceplane, the Diabolus X has 2530 Delta V with the toroidal aerospike and is meant for Duna (is that enough Delta V to land and return?) Admittedly the jet engines are a bit of dead weight, but it is an SSTO that docked to the Carrier under it's own power and I only plan to reuse them for reentry. The spaceplanes both can function as escape pods, and I regularly dock mk1 pods with heatshields to transfer crew between the ground and the carrier.

The Diabolus X has enough delta-v to land and return, but remember that it needs a TWR larger than 1 to take off vertically. As for the Valkyria III, I'd say it also has enough delta-v to return, so seems safe enough.

To know how much delta-V you'll need, use this:

http://forum.kerbalspaceprogram.com/threads/96985-1-0-4-WAC-s-Delta-V-Map-continued-OPM-now-included-%28July-4th-2015%29

[Edax]

The Diabolus X has enough delta-v to land and return, but remember that it needs a TWR larger than 1 to take off vertically. As for the Valkyria III, I'd say it also has enough delta-v to return, so seems safe enough.

To know how much delta-V you'll need, use this:

http://forum.kerbalspaceprogram.com/threads/96985-1-0-4-WAC-s-Delta-V-Map-continued-OPM-now-included-%28July-4th-2015%29

It's my plan to have the Diablous X take off Duna horizontally, assisted by two twitch engines. Are horizontal takeoffs viable on Duna? (I've only done that successfully on the Mun and Minmus with "puff" engines, since they had low gravity). Duna has atmosphere so maybe the wing controls will be enough to get the nose in the air?

[SpacedCowboy]

Don't you need two science kerbs to run the lab or did that get changed up? You must have hours and hours into the assembly. That's an awesome ship you've got there! It would be a pity to get there and not be able to run the science lab.

[Yemo]

Good point, I forgot to pack probes onto the ship.

I meant it more like, send probes first and then a giant ship with kerbals on board, not small probes on your giant ship.

My first interplanetary missions (probes) are usually below 18t and 30 parts (depending on installed mods of course), for the whole mission...

edit: I just built a 20part/6ton atmospheric lander probe with 5km/s dV (should be enough for Eve and Duna), lander legs, Com Dish, parachute and 4 light experiments (2 of them from DMagic), without upgrading R&D...

Edited July 5, 2015 by Yemo

[Edax]

I meant it more like, send probes first and then a giant ship with kerbals on board, not small probes on your giant ship.

My first interplanetary missions (probes) are usually below 18t and 30 parts (depending on installed mods of course), for the whole mission...

Eh, giving that the launch window for Duna effectively makes the delta V requirements as low getting to Minmus, getting to Duna orbit isn't my concern, it's the landing part that's got me nervous. I mean, can a plane glide effectively in Duna and slow down using wing imputs alone? Or do I need to fire the engine to slow down to a safe landing speed? Reason I don't want to send a probe first is that by the time it get's there, I'll have missed the launch window.

- - - Updated - - -

Don't you need two science kerbs to run the lab or did that get changed up? You must have hours and hours into the assembly. That's an awesome ship you've got there! It would be a pity to get there and not be able to run the science lab.

According to the wiki, it says I only need one.

[Yemo]

Eh, giving that the launch window for Duna effectively makes the delta V requirements as low getting to Minmus, getting to Duna orbit isn't my concern, it's the landing part that's got me nervous. I mean, can a plane glide effectively in Duna and slow down using wing imputs alone? Or do I need to fire the engine to slow down to a safe landing speed? Reason I don't want to send a probe first is that by the time it get's there, I'll have missed the launch window.

Well, gliding is possible depending on the mass to lift ratio. So you would have to test or calculate. Same goes for aerobreaking (I hope you have aerobrakes?), try or calculate/guesstimate, but the Duna atmo is very thin.

Failure is part of the fun. Though personally I try to minimize my costs of failure by limiting the scope when trying something new. That is why I recommended a minimal mission first. I just checked and I can build a complete Duna/Eve probe mission (4 experiments, landing legs and so on) with 20 parts and 6 tons.

For such small craft, launch windows especially to Duna are much less of a concern, since it is fairly easy to add another 1-2km/s dV.

But you already built that giant thing, might as well test with that directly.

If that is the challenge/mission you want, go for it.

Worst case, just load an earlier save and try something different.

[Edax]

Well, gliding is possible depending on the mass to lift ratio. So you would have to test or calculate. Same goes for aerobreaking (I hope you have aerobrakes?), try or calculate/guesstimate, but the Duna atmo is very thin.

Failure is part of the fun. Though personally I try to minimize my costs of failure by limiting the scope when trying something new. That is why I recommended a minimal mission first. I just checked and I can build a complete Duna/Eve probe mission (4 experiments, landing legs and so on) with 20 parts and 6 tons.

For such small craft, launch windows especially to Duna are much less of a concern, since it is fairly easy to add another 1-2km/s dV.

But you already built that giant thing, might as well test with that directly.

If that is the challenge/mission you want, go for it.

Worst case, just load an earlier save and try something different.

Hmm, maybe I should have stuck the engine on the front of the plane like it did with the Valkyria III, that way the wings would have been pointed in the right direction for gliding, and I'd have thrust slowing me down...

Guess I'll just have to see for myself.

[Edax]

So, now that the ship is fueled up, loaded with probes and 2 disposable fuel tanks for the spaceplanes, I think I'm ready to head to Duna. I think i'll just skip the launch window for now, it's only 250 extra Delta V at the moment.

Edited July 5, 2015 by Edax

[Edax]

Essentially what happened on my trip to Duna.

[Wanderfound]

Eh, giving that the launch window for Duna effectively makes the delta V requirements as low getting to Minmus, getting to Duna orbit isn't my concern, it's the landing part that's got me nervous. I mean, can a plane glide effectively in Duna and slow down using wing imputs alone? Or do I need to fire the engine to slow down to a safe landing speed?

They're a bit dated now, but for some more examples of the challenges of flying and landing on Duna, see:

(the Duna landing is in part 3)

Basically, flying on Duna is similar to flying at moderately high altitude on Kerbin. The hard part is the landing; no runways, low traction, low gravity. A wide and long wheelbase plus drag chutes or retrothrusters (for post-touchdown braking) are highly recommended.

Edited July 15, 2015 by Wanderfound

[Good_Cat]

So, now that the ship is fueled up, loaded with probes and 2 disposable fuel tanks for the spaceplanes, I think I'm ready to head to Duna. I think i'll just skip the launch window for now, it's only 250 extra Delta V at the moment.

http://i.imgbox.com/LbOqcwOH.jpg

I've put hundreds of hours in KSP nut never tried something like that, my spaceplanes are better than my rockets, rockets i've usually forgot something.

That looks badass, gotta give that a go myself.

I might have to try replicate this, download burn together and take 2-3 Mk3 SpacePlanes into orbit with full cargo bays, tweak a my Mk1 to fit a nuke on them.

I take it Duna with its thinner atmosphere needs are larger wing area???

[Sharpy]

The Diabolus X has enough delta-v to land and return, but remember that it needs a TWR larger than 1 to take off vertically.

You may take off horizontally on airless worlds that have large spans of flat areas (Minmus?) with TWR < 1. You just need to speed up near orbital speed horizontally. (OTOH I'm afraid Duna and Ike aren't exactly flat enough.)

[Edax]

I've put hundreds of hours in KSP nut never tried something like that, my spaceplanes are better than my rockets, rockets i've usually forgot something.

That looks badass, gotta give that a go myself.

I might have to try replicate this, download burn together and take 2-3 Mk3 SpacePlanes into orbit with full cargo bays, tweak a my Mk1 to fit a nuke on them.

I take it Duna with its thinner atmosphere needs are larger wing area???

If you watch my video, you'll see that I approached the ground pretty fast, about 140m/s with gear down and airbrakes deployed. I had to do a crazy rocket parachute landing to kill all the velocity and I probably strained the landing gear tolerance doing it. I recommend plenty of twitch engines, both pointed down and forward so you can both hover and slow down. Maybe bigger wings will help, but I think it's the lack of drag that makes landing so dangerous.

- - - Updated - - -

You may take off horizontally on airless worlds that have large spans of flat areas (Minmus?) with TWR < 1. You just need to speed up near orbital speed horizontally. (OTOH I'm afraid Duna and Ike aren't exactly flat enough.)

As seen in my video, taking off is a breeze if you have a nice smooth hill. You can expect to find the flattest terrain in craters, which is where my landing site was.

Edited July 23, 2015 by Edax