Shuttle Challenge v4 - The STS thread [Stock and Mod Friendly] [THREAD CLOSED 06.08.17]

[michal.don]

On 20. 2. 2017 at 7:21 AM, Speeding Mullet said:

Ah yes then someone comes along and blows the scoring out of the water hehe.  Was it a mistake to remove the 168t fuel pod?

Well, I think in a few weeks there will be many more entries lifting the pod to the SOI boundary - as soon as people start designing their interplanetary shuttles. When you have to do the burn to Laythe from LKO (cca 2000 m/s) with a lot of equipment stowed in the cargo bay, taking 40 tonnes to high Kerbin orbit seems like a walk in the park

About the 168t pod - I'm not really sure. It is a lot of weight, and requires the shuttle to have insane amount of Delta-V in the tanks, as well as high TWR to even lift prom the pad. Compared to even the 80t pod from v3, it is way more difficult - while I managed to take the 80t pod to the SOI boundary, I didn't manage to take the 168t to LKO. So, if you want a challenge that only the best shuttle designers and pilots can complete, then this might be the one. If, on the other hand, you seek something that most people can achieve with their regular shuttle, I'm afraid that this one will be too difficult for the most of them.

Michal.don

[53miner53]

2 hours ago, michal.don said:

Well, I think in a few weeks there will be many more entries lifting the pod to the SOI boundary - as soon as people start designing their interplanetary shuttles. When you have to do the burn to Laythe from LKO (cca 2000 m/s) with a lot of equipment stowed in the cargo bay, taking 40 tonnes to high Kerbin orbit seems like a walk in the park

About the 168t pod - I'm not really sure. It is a lot of weight, and requires the shuttle to have insane amount of Delta-V in the tanks, as well as high TWR to even lift prom the pad. Compared to even the 80t pod from v3, it is way more difficult - while I managed to take the 80t pod to the SOI boundary, I didn't manage to take the 168t to LKO. So, if you want a challenge that only the best shuttle designers and pilots can complete, then this might be the one. If, on the other hand, you seek something that most people can achieve with their regular shuttle, I'm afraid that this one will be too difficult for the most of them.

Michal.don

I have an idea: how about we have STS-1b use the 40t fuel pod(which I think is out of the payload capabilities of the actual space shuttles BTW) and have a STS-1c with an 80t fuel pod and a STS 1d with a 160t fuel pod.  

Edited February 25, 2017 by 53miner53

[michal.don]

4 hours ago, 53miner53 said:

I have an idea: how about we have STS-1b use the 40t fuel pod(which I think is out of the payload capabilities of the actual space shuttles BTW) and have a STS-1c with an 80t fuel pod and a STS 1d with a 160t fuel pod.  

Well, it was along these lines in the v3 of this challenge. So it's quite possible that Speeding Mullet will make these sub-missions again. The thing that bothered me a bit wat that the 168t pod was a clipped nightmare of several ore tanks so it could fit in the standart MK3 bay

To be honest, I take these bonus missions just as a thing to do in the meantime, before the next full mission is released, so If this is the way it goes, I don't really mind.

Michal.don

[swjr-swis]

On 2/20/2017 at 7:21 AM, Speeding Mullet said:

Was it a mistake to remove the 168t fuel pod?!

Well, if you guys decide it was a mistake and want it back...

Spoiler

https://kerbalx.com/swjr-swis/SWiS-STS-168t-Ore-Pod

 

 

[BubbleWrap]

Since there is a 40 day lead time on the asteroid I ordered for STS-9, I thought I'd send out Mun STS-1 so I could get the album ready. Unfortunately, I miscalculated the fuel usage across the three sets of engines on the orbiter, and compounded the problem by not lowering down to the orbit I'd calculated fuel requirements for before landing.... so Orbiter Number 10 is currently stranded on the Munar surface. At least they have a base, I guess? Now I have to launch a rescue mission within 18 days. Orbiter 7 is on a Minmus flyby trajectory, Orbiter 8 is docked to the space station, and Orbiter 9 is en-route to the manned orbital observatory, and none of them are VTOL capable anyway. I guess this calls for some careful thought. On the plus side, Orbiter 10 worked perfectly for the actual landing and deployment, so a revised follow-up attempt shouldn't have any issues.

[53miner53]

28 minutes ago, swjr-swis said:

Well, if you guys decide it was a mistake and want it back...

  Reveal hidden contents

https://kerbalx.com/swjr-swis/SWiS-STS-168t-Ore-Pod

 

 

I think I may have to launch this after I complete STS-4, because of my use of the first launch as a test mission for a larger fuel tank for the LR orbiter

[SolidJuho]

Hey again. I just added my shuttle to KerbalX, and as you can see, only one part was from mods. Mechjeb.

https://kerbalx.com/SolidJuho/Solid-Shuttle-02

 

[sdj64]

On 2/24/2017 at 9:33 PM, vladd148 said:

Howdy!

I did see your shuttle in the V3 challenge thread, and I must admit I was inspired by the design. However, I never downloaded it, I created my own from scratch. And since I could never quite figure out how to get the external tank on top, I re-designed it and turned it into a Buran style shuttle.

*image*

Oh, cool.  I like the redesign with the four nukes.  It should do very well on the Mun and Duna.  

The top tank uses a clipped decoupler and the fairing's longer attachment nodes to float it in front of the nose.

[vladd148]

Finished the "Duna" mission 1 with my own little twist to it. In the Galileo Planet Pack, the closest planet is Niven, a Venutian planet.

 

The Delta V required is slightly more than Duna, making it a slightly more challenging mission. Due to it's atmosphere, landing on it will be a significant challenge!

 

Mission album:

http://imgur.com/gallery/KM5oD

And some teasers:

[regkoestoer]

Hi, this is my first post! I saw this exciting thread and thought one of my old designs might be up for the challenge for STS-1a. It's called the Extension Mk.2. It has a simple traditional shuttle layout (nothing fancy yet). Originally, I made it for Duna missions, hence the nuke engines.

album link is here: http://imgur.com/a/iuRNS

Mods used:

- MechJeb (for ascent guidance and delta-V calculations)

- BD Weaponry is installed (but not used)

- apart from that, the shuttle is stock

The mission was fairly straight-forward. Ascent final inclination was 45 degrees and the craft was circularized at 200 km altitude (all using the launch vehicle). At that point the orbiter separates and we start to look for a de-orbit point. After that we did the de-orbit burn. I lost some control at the end of the long re-entry run and recovered, but we overshot the KSP a bit.

Some teasers:

 

So I landed at the island airstrip. I had to use the main engine a bit to avoid stalling on the approach. But it was all good and we landed. I parked the shuttle in the fighter squadron hangar.

I think I can claim the Commander badge (landing at the island airstrip is ok, right?)

Gonna do the next missions and perhaps also retry the STS-1a with weirder designs. I want that Skunkworks Badge!  

Edited February 28, 2017 by regkoestoer

[AeroGav]

On 28/02/2017 at 3:52 PM, regkoestoer said:

Hi, this is my first post! I saw this exciting thread and thought one of my old designs might be up for the challenge for STS-1a. It's called the Extension Mk.2. It has a simple traditional shuttle layout (nothing fancy yet). Originally, I made it for Duna missions, hence the nuke engines.

album link is here: http://imgur.com/a/iuRNS

Mods used:

- MechJeb (for ascent guidance and delta-V calculations)

- BD Weaponry is installed (but not used)

- apart from that, the shuttle is stock

The mission was fairly straight-forward. Ascent final inclination was 45 degrees and the craft was circularized at 200 km altitude (all using the launch vehicle). At that point the orbiter separates and we start to look for a de-orbit point. After that we did the de-orbit burn. I lost some control at the end of the long re-entry run and recovered, but we overshot the KSP a bit.

 

So I landed at the island airstrip. I had to use the main engine a bit to avoid stalling on the approach. But it was all good and we landed. I parked the shuttle in the fighter squadron hangar.

I think I can claim the Commander badge (landing at the island airstrip is ok, right?)

Gonna do the next missions and perhaps also retry the STS-1a with weirder designs. I want that Skunkworks Badge!  

Ah 3 nervs at the back !   I kind of like the idea but makes it so tail heavy.   With empty cargo bay CG must be in the middle of that short liquid fuel fuselage section or something?    

Which then raises the issue of how do you control pitch.  The elevons are going to be so close to your CG as to be useless.

I have a new idea though. 

Attach elevons to the front edge of the strakes, set them to control pitch, and the elevons on the back of the wing to do roll only.    The elevons on the front edge of the strakes will be quite far forward so will have leverage, also when flaring for touchdown, they will be helping to lift the craft rather than pushing it into the ground like aft mounted controls.  You'll need to set their authority rating to a negative number in the tweakables however or they'll move in the wrong direction.

When you've invested so much mass  (12 tons!) in a high efficiency, fairly high thrust propulsion system, it's tempting to size the booster/ext tank to only get you to 1700 m/s and have those NERVS push you the rest of the way.   Needs a good lift/drag ratio for that though,  the CG will also move way forward when you load the cargo bay, which is going to need a way to keep the nose up without killing aerodynamic efficiency.

 

Edited March 5, 2017 by AeroGav

[regkoestoer]

2 hours ago, AeroGav said:

Ah 3 nervs at the back !   I kind of like the idea but makes it so tail heavy.   With empty cargo bay CG must be in the middle of that short liquid fuel fuselage section or something?    

Which then raises the issue of how do you control pitch.  The elevons are going to be so close to your CG as to be useless.

I have a new idea though. 

Attach elevons to the front edge of the strakes, set them to control pitch, and the elevons on the back of the wing to do roll only.    The elevons on the front edge of the strakes will be quite far forward so will have leverage, also when flaring for touchdown, they will be helping to lift the craft rather than pushing it into the ground like aft mounted controls.  You'll need to set their authority rating to a negative number in the tweakables however or they'll move in the wrong direction.

When you've invested so much mass  (12 tons!) in a high efficiency, fairly high thrust propulsion system, it's tempting to size the booster/ext tank to only get you to 1700 m/s and have those NERVS push you the rest of the way.   Needs a good lift/drag ratio for that though,  the CG will also move way forward when you load the cargo bay, which is going to need a way to keep the nose up without killing aerodynamic efficiency.

 

Thanks for the feedback! “Tail Heavy” is the right word for this design. Even under load, the CG rarely moves forward beyond halfway of the length of this 44-ton craft. For STS-1a I tricked out the fuel loadout a bit so I only had a bit of fuel in the wing strakes and the other tanks were empty. So I moved the CG to the front slightly. Even then. it was just slightly ahead of the liquid fuel tank.

The problem with CG so far in the back is that it needs a (very) steady hand during re-entry, any excessive AoA (usually above 10 deg) will flip the plane over, spin uncontrollably, and then it’ll fly backwards in atmosphere. I used a bunch of RCS thrusters to control the nose for that problem (barely).

Actually the pitch control felt quite OK (I only used the inboard Elevons for pitch and the outboard ones for Roll, and that was OK so far) as long as we keep the AoA in control (i.e. don’t get into a spin). Maybe its because the CL is very close behind the CG, almost like super-maneuverable fighters. But you have a great point there with the Elevons on the front strakes. Does it mean they function kinda like Leading Edge Slats? Anyways I’ve added it to the “Extension Mk.2B” version and I’ll try it out tomorrow!

Yes, the booster stage I used for this mission was kind of overkill (it can get the shuttle to LKO on its own, with fuel to spare). You’re right, for LKO missions I only need 1700 dV from the booster stage and then the craft has enough dV (3900) to circularize and everything. Next time I’ll try a more efficient launch with SRBs rigged for 1700 dV instead, as long as my TWR can carry me! (the 3 Nervs only makes 0.4 TWR so I hope it climbs)

[53miner53]

46 minutes ago, regkoestoer said:

Thanks for the feedback! “Tail Heavy” is the right word for this design. Even under load, the CG rarely moves forward beyond halfway of the length of this 44-ton craft. For STS-1a I tricked out the fuel loadout a bit so I only had a bit of fuel in the wing strakes and the other tanks were empty. So I moved the CG to the front slightly. Even then. it was just slightly ahead of the liquid fuel tank.

The problem with CG so far in the back is that it needs a (very) steady hand during re-entry, any excessive AoA (usually above 10 deg) will flip the plane over, spin uncontrollably, and then it’ll fly backwards in atmosphere. I used a bunch of RCS thrusters to control the nose for that problem (barely).

Actually the pitch control felt quite OK (I only used the inboard Elevons for pitch and the outboard ones for Roll, and that was OK so far) as long as we keep the AoA in control (i.e. don’t get into a spin). Maybe its because the CL is very close behind the CG, almost like super-maneuverable fighters. But you have a great point there with the Elevons on the front strakes. Does it mean they function kinda like Leading Edge Slats? Anyways I’ve added it to the “Extension Mk.2B” version and I’ll try it out tomorrow!

Yes, the booster stage I used for this mission was kind of overkill (it can get the shuttle to LKO on its own, with fuel to spare). You’re right, for LKO missions I only need 1700 dV from the booster stage and then the craft has enough dV (3900) to circularize and everything. Next time I’ll try a more efficient launch with SRBs rigged for 1700 dV instead, as long as my TWR can carry me! (the 3 Nervs only makes 0.4 TWR so I hope it climbs)

I was having the same problem with CoM/CoL because I wanted to avoid my usual problem with planes being too stable and being unable to pitch up at 100m/s. I ended up moving some of my wings backward so the CoM would stay in front of CoL no matter what I did with fuel load. Just don't forget to check with the tanks at the nose empty if you have some.

[AeroGav]

@regkoestoer  TWR  combines with lift/drag ratio to say whether an airplane can gain energy (accelerate or climb).  Eg.  If you have 0.4 to 1 TWR but your L/D ratio is 4 to 1  then you're going up.    However a shuttle clone won't manage that L/D ratio.    My baby shuttle series get about 2.5 to 2.8 to 1 in supersonic/hypersonic flight.     I have no external RCS ports  , nothing radially attached except aero surfaces,  and i have attached nose cones to the back of my engine's attach nodes to reduce drag. I've also got a 2.5m nose cone on the  unused 2.5m node of the mk3 engine mount.  Oh and did i tell you my wings are angled up with about 4 degrees of incidence, so i can glide with the body at zero aoa?   Also I angled the strakes up a few degrees more than the  main wing, for two reasons  a) they stall first, making it nose down when you get near stall  b) it trims the nose up for level flight without having to push "down" with the rear elevons, which improves gliding efficiency.

Still there's one more factor working in your favour, orbital freefall effect will be supporting most of the weight of the craft already by 1500 m/s,  so the amount of lift we need is less.   In practice this means you'll be really high up and still at low aoa, so drag will be greatly lessened. 

[AeroGav]

OK, I'm finally ready to move on from the STS 2a badge I earned back here -

Next compulsory mission is the Hubble telescope mission.   This was quite a problem for my "baby shuttle", since it is the full length of a CRG100 bay and baby shuttle only had CR50 worth of space, due to carrying its fuel internally.  Stretching the fuselage would mess up the proportions, making it too long for the wings.   I came up with this Block 2 prototype, which was able to 

offer CRG50 plus CRG25 space thanks to the wing tip drop tanks.    But even that was not enough for the telescope,  so two separate variants were developed in parallel.

The first leverages the considerable LF capacity of its wings and strakes.  Two side mounted NERVs are combined with two droppable Whiplash jet engine boosters and some jettisonable Terrier motors to bridge the gap between the Whiplash and NERV operating regimes.  I was able to complete the mission with block 3a,  and it was easier to fly than the vertically launched brethren due to not having to master tricky gravity turns, however it does require patience, powered flight lasting 10 to 15 minutes longer than the rocket-only craft.

However,  I felt this was getting a little too far away from the spirit of this challenge, taking off horizontally and using jet engines.   It's not an SSTO , because it decouples engines and fuel tanks, but it's still too SSTO-like for comfort.    

Baby Shuttle Block 3a flying to orbit -

Baby Shuttle Block 3a deploying and assembling the telescope (not very interesting vid, click spoiler if you really want to see it)

Spoiler

 

..  

.

 

This design has probably been chopped around too much and is getting buggy.   The "can't undock" Kraken hit this ship and the only way I could resolve this was to install Kerbal Inventory System and send an engineer with a power screwdriver up to detach the offending port.  Rather than land his capsule,  I had him hitch a ride on the shuttle back. The cockpit already had 4 Kerbals, so we improvised.  Did he make it?    Sort of..

I'm incredibly proud of how the re-entry went, considering the starting point.

_{To begin with, I had never tried to hit the space centre from an inclined orbit before, not only would we need to come down with our PE in the right location with respect to east/west , i'd need to make that coincide with the point our inclined orbit crosses the equator.   Then to cap it all,  i started aerobraking from 650km with my PE on the dark side of Kerbin (another night landing?) and continued to make passes in a high drag attitude until my AP and PE were down to 120 and 40km respectively, before realising i better check the location of the space centre.     As it happenned,  my previous PE had been directly overhead the space centre and due to the rotation of kerbin, each subsequent PE was going to end up further east of the space centre.}  

_{At that point i set the nose for best glide and tried to stretch the re-entry, hoping to somehow stay aloft till kerbin rotated completely around again.   After the 120km/40km skim, we left the atmosphere again  just as the sun was setting over the meteorite crater.    Our AP and PE were now just 71 and 29km, peaking just over the space centre (surely the worst place !) , falling back into the atmosphere in the "badlands" continuent east of KSC at sunrise.  Due to lift, we started up again at 41km rather than our 29km PE and in fact just made it over 47km , giving the cockpit a brief respite from heating.  This occured over the ocean halfway between  "badlands" and "big desert" continent,  our PE now at -50km due to lost velocity.} 

_{Maintaining the hypersonic glide as we passed over the impact crater again, we enjoyed brief pause in our descent at 36km over the mountains marking the western edge of the big desert, just as night fell.   Halfway across this desert, at 32km and mach 5.4, peak termperature of 92% was reached in the cockpit.  By 28km,  we were still over the desert and it was clear no more bounces were forthcoming.   In danger of undershooting, i added a little power from the NERV engines to stretch our glide.   This worked far better than anticipated , consuming only 200dV. Unfortunately our inclined orbit was going to peak at its furthest north point as we reached the space centre's longditude.   I would need to stay hypersonic and above 20km while somehow executing a 135 degree turn to the south.   Yet this too worked well,  making a wide arcing turn at a 35 degree bank without creating excess drag.    On final approach we had rather too much height.   Two 360 degree orbits were made , then an attempt was made to sideslip  (full left rudder with full right aileron - plane doesn't turn but drag is made as the rudder and ailerons fight each other ).  We didn't loose control, but didn't loose much height either.    Finally, i lost patience and just rolled the orbiter inverted and performed corkscrewing manuver.  Very risky - but it worked !}
    

Now, like I say, I felt Block 3a was too much of an airplane, so i developed a vertical launch version.   I don't think a Space shuttle type vehicle, launching with solid fuelled boosters and a liquid fuelled higher ISP upper,  makes any sense in a universe where jet engines are so utterly awesome.   In reality, turbo ramjets get you to about mach 4 which is only 16% of orbital velocity, not 55-60% like in KSP ! 

So for Block 3b ,  I treat the Whiplashes as experimental Scramjet engines that cannot be used for takeoff, so we have SRBs to boost us over 15% of orbital velocity, which is the lowest speed at which scramjets can start to work.   After the scramjets are done, we are back to Terriers and Nervs.    

I only flew this one to 650km, but it got there with the same payload and slightly more leftover fuel, so I think you can accept that this mission could also be accomplished with Block 3b, if you feel 3a is invalid.

Operating economics

Baby Shuttle Block 1   

Cargo Bay  -  CRG - 50

Launch Cost (3 kickbacks)  11,880 Funds 

Baby Shuttle Block 2

Cargo Bay - CRG - 75

Launch Cost  16,314 Funds (2 external tanks & 2 srb not recovered, one srb with chutes - recovered) 

Baby Shuttle Block 3a

Cargo Bay - CRG 100

Launch Cost  10,602 Funds (2 whiplashes and 2 terriers staged off) 

Baby Shuttle Block 3b

Cargo Bay - CRG 100

Launch Cost  44,694 Funds (4 whiplashes, 4 Terriers, 12 Hammers and 12 Fleas  staged off) 

3a and 3b could have been made cheaper still by hanging on to the air intakes (they are light), but i put them on the Whiplash nacelles for the sake of realism.

I'm still not convinced with 3b either TBH,  it's getting a bit too "Kerbal" in my opinion, I think this all stems from my reluctance to use an external tank on account of balance issues, but i've ended up tying myself in knots trying to get enough cargo onto a properly proportioned orbiter that also has to carry fuel internally.

Fortunately , I have an idea for overcoming the centre of mass issue.  I'm going to use vacuum engines on the orbiter, and atmo engines on the bottom of the external tank.   As fuel burns off, CoM will move closer to orbiter, so the pitch up moment from the engines on the tank get stronger.  But, at the same time the orbiter is getting higher , so it's vacuum engines get stronger relative to the atmo engines on the tank and boosters, counteracting the effect.  I am also arranging it so that half the external tank's engines can be decoupled when the pitch up effect gets too strong.    Still tuning it but looks to be a wild ride.   So far we're talking 6 kickbacks,  6 Reliants, 3 terriers and a NERV.   The ET is made of Kerbodyne parts, the launch cost of this thing's going to be staggering.  Just as well we're in Sandbox eh!

Edited March 1, 2017 by AeroGav

[53miner53]

STS-4 Complete! Do I get extra points for landing the rescued shuttle at the island runway?

https://drive.google.com/open?id=0B0eMT8zRijNmSWhWSXQxWVNRRFE

I also launched another 40t fuel pod to 350km. 

I used this as multiple tests at once: how much delta v can I get from the LKO design, can I do a direct reentry from 350km without a heatshield, new Saturn Shuttle launch stack for the LR shuttle, and I ended up losing control during the aerobraking with the LR shuttle and stretched the glide back to the KSC instead of using the quicksave I had made. 

[Scabank]

Hello, i want to get Badge 9 as well. There is not an aswer yet on my 4-8 post i linked before... anyway ;)... I think it is approved so i will post the last challenge for me atm, eventually i will come back in a few weeks with more. Greetings

 

OMG !!  HAVE YOU EVER WANTED A CONTAINERSHIP GO TO SPACE SO BADLY YOU JUST BUILD 2 GIANT FISTS OUT OF FIRE AND THUNDER TO PUNCH IT RIGHT THROUGH THE SKY !!

 

 

[Speeding Mullet]

Hi everyone just dropping in quickly to say WOOOT WE MADE THREAD OF THE MONTH!

Thanks to you all for helping make this happen.  Without you all designing and flying wacky contraptions this wouldn't have been possible so again thanks to you all, and its definitely a we, not me!

I'm just having a busy couple of days with some bosses in town but wanted to let you all know that I am still here, and will review every single post ina big catch up this Saturday.  Looking forwards to a badge spree .

SM

[53miner53]

I found taking the 168t fuel pod to LKO to be easy, though my shuttle was designed entirely for the purpose of taking whatever will fit in the cargo bay to LKO. 

https://drive.google.com/open?id=0B0eMT8zRijNmM1VCZ3NFYjBVZ3c

I think this should be a section of the challenge again.

[wrench-in-the-works]

5 hours ago, Speeding Mullet said:

I'm just having a busy couple of days with some bosses in town but wanted to let you all know that I am still here, and will review every single post ina big catch up this Saturday.  Looking forwards to a badge spree .

Glad to see you're still alive, and good luck with that massive review, I have a four hour video.

[Shadow dream]

 

 

Congratulations to Thread of the Month!

 

My Mission #09 is going well so far. I have a Craft in Orbit waiting for an Asteroid Class B to arrive. Actualy I'm playing Poker right now because I will try my "old" shuttle again. (Many complications with new designs... U__U ) At least I'm pretty lucky with that Asteroid since it comes in at about 500km and should be small enough to not wreck my shuttle at reentry. I have tested flight with much heavyer Ore tanks and it seems ok so far. Let's see if I can do a Runway Landing with the least aerodynamic payload too...

Here are some teasers from planing: What I have done is to build a small probe which I can dock onto the Asteroid. To keep it real (following Mission #03) I also have a MMU onboard to place that docking claw. Beyond that I thought the only thing I might need is more dV, so I tossed in some ejectable fuel tanks. Still got 1200dV left in parking orbit - fingers crossed!

Spoiler

 

[StahnAileron]

Good Day All,

I don't mean to take this thread on a tangent, but it's the inspiration for what I'm attempting to do: build a working Shuttle System. (I won't be entering the challenge.)

I built a shuttle (actually, a couple; explanation upcoming) that launches quite well. I spent time tweaking it for the major stages of launch: initial launch, SRB burnout > SSME-only phase, orbital insertion. In a nutshell, it flew as intended. I just needed to control pitch-over, AoA, and flipping over before dumping the ET. For the most part, it was far more stable during launch than I originally thought I could get it.

Note I mentioned stable launching. Recovery is a whole other matter for some reason. I seem to be facing either trans-/supersonic instability (does stock aero do this?) or I'm facing some horrible body lift issues with the MK3 design I'm using while at high speeds. The CoL is a good distance behind the CoM and DCoM (per RCSBuildAid). However, I did notice during a few re-entry tests with F12 on that the MK3 bodies were generating a lot of body lift. Re-entry is usually fine if I keep a reasonable AoA, but if I hit a critical angle of some sort, it flips and either flies backwards or becomes uncontrollable. Nothing I do helps (if anything, making it worse) until I hit lower speeds. Typically this is under 200m/s or so. I've tried to replicate this, but I apparently need to go stupidly fast in relatively thin atmosphere for this to kick in. (Thin enough that natural CoL won't affect changes in prograde fast enough, but still thick enough that my control surfaces still work and create body lift on the MK3 parts.)

Have any of you had to design around/take into account body lift issues with shuttle designs? I'm more used to Mk2 designs where the "body" lift is already accounted for in the SPH (since MK2 bodies are treated as wings.) I think the body lift at high speeds is screwing me over whenever I try to do any maneuvers at those speeds for my MK3 design. (Honestly, this is the first time I've bothered this much with a MK3 design.) The CoL is about a small MK3 fuel tank behind the CoM. My re-entry tests have been with mostly full tanks coming back down. I'm suspecting the body lift is enough to shift the CoL ahead of the CoM. (Relevant parts ahead of the CoM are just a large MK3 Cargo Bay, a small MK3 Cargo Bay, and the MK3 cockpit. Not much, really.) F12 showed those parts generating some absurd body lift during a few of my tests, IIRC.

I'll post pics of the design if you think it might help... Or you're just curious what kind of design I made. I have a modded install. I started with a mostly stock design. The exceptions were the ET (FuelTankPlus parts to mimic the actual STS ET) and separation motors (from BlueDogDesign). It's got more modded as I iterated the design: more FTP tanks and a switch to OPT wings. (The switch in wings was to test my instability problems... That, plus extra fuel and lift.) I only have the most recent design though. I wasn't saving versions, unfortunately.

[53miner53]

9 minutes ago, StahnAileron said:

Note I mentioned stable launching. Recovery is a whole other matter for some reason. I seem to be facing either trans-/supersonic instability (does stock aero do this?) or I'm facing some horrible body lift issues with the MK3 design I'm using while at high speeds. The CoL is a good distance behind the CoM and DCoM (per RCSBuildAid). However, I did notice during a few re-entry tests with F12 on that the MK3 bodies were generating a lot of body lift. Re-entry is usually fine if I keep a reasonable AoA, but if I hit a critical angle of some sort, it flips and either flies backwards or becomes uncontrollable. Nothing I do helps (if anything, making it worse) until I hit lower speeds. Typically this is under 200m/s or so. I've tried to replicate this, but I apparently need to go stupidly fast in relatively thin atmosphere for this to kick in. (Thin enough that natural CoL won't affect changes in prograde fast enough, but still thick enough that my control surfaces still work and create body lift on the MK3 parts.)

Have any of you had to design around/take into account body lift issues with shuttle designs? I'm more used to Mk2 designs where the "body" lift is already accounted for in the SPH (since MK2 bodies are treated as wings.) I think the body lift at high speeds is screwing me over whenever I try to do any maneuvers at those speeds for my MK3 design. (Honestly, this is the first time I've bothered this much with a MK3 design.) The CoL is about a small MK3 fuel tank behind the CoM. My re-entry tests have been with mostly full tanks coming back down. I'm suspecting the body lift is enough to shift the CoL ahead of the CoM. (Relevant parts ahead of the CoM are just a large MK3 Cargo Bay, a small MK3 Cargo Bay, and the MK3 cockpit. Not much, really.) F12 showed those parts generating some absurd body lift during a few of my tests, IIRC.

I was having the same problem with instability, though it was occuring when I was hypersonic. I had pinned it down to the fact that my testing hadn't taken into account that I would drain the monoprop tanks during a mission. I found that a good solution was to make sure my CoL was behind my CoM when the nose tanks were empty and the tail tanks were full. 

[Ribby Kerman]

I may try this but seeing as all my previous shuttles have failed miserably because of wings exploding it will be a challenge (I'm still in 0.90 because I'm not sure my CPU can handle 1.2 and I don't want to lose my progress). I might try the rescue one because I already have 1 broken shuttle in a lopsided orbit. Is it allowed to be in 0.90? Also can i save all my rockets and space stations and put them into a new version or do I have to start from scratch? Thanks a lot. Expect to see some of my shuttles soon.

 

-Ribby Kerman

[zolotiyeruki]

Argh!  The Kraken has struck my install, and one of my two Duna shuttles has disappeared.  The other is probably short on fuel to get home as well.  And there are some issues with the design as well, so I'm going to have to start those two missions over.  Grrr.