SPACE SHUTTLES (Launch or SSTO)

[qzgy]

42 minutes ago, Alpha_Gametauri said:

I finished rebuilding the Shuttle, what now? How do i share it?

KerbalX is popular. Dropbox or google drive works, but I highly recommend KerbalX

You have to find the craft file. Go to saves, then click the save your craft is in. In that folder, there is a folder marked 'Ships' When you open that folder, you have to click the place where your ship is saved. After clicking through that, you find your craft file.

Which you can just upload

[Alpha_Gametauri]

Crap, i accidentally put a strut in there from KW Rocketry. Should i remove it and re-upload?

 

https://kerbalx.com/Alpha_Gametauri/Kerblantis/parts

Edited August 26, 2017 by Alpha_Gametauri

[Andetch]

So I have been working on a little physics tester vehicle.... It doesn't take passengers, or payload, it is purely to prove flight concept of asymmetrical design. The only mod is Mechjeb, but it is not needed so you can fly stock. I was just using mechjeb to look at figures.

It works like this;

Top stage weighs approx 50% of lower stage. Engines are both mainsails, top stage engine is restricted to just over 50% thrust output for launch - you will need to adjust the thrust of each engine in flight so pin both open!

Launch at full throttle, it should stay fairly stable, play with the top stage engine thrust to get it stable - it can also help with the grav turn. It should be 100% thrust fairly quickly. Stay below mach 1 under 8,000 M. Around 8.000 M you will start to notice the nosing up effect happening, especially at full throttle. This is where you start reducing the lower stage engine thrust to counter for the moving centre of mass. As the lower stage engine reaches around 50% thrust the bottom stage fuel should be spent. You should also be moving fast enough to coast for a while, and then at around 15 degree climb angle or 50,000 M you can hit full throttle and get into orbit. Coming back down was all going well until I let mechjeb take over and it instantly spun it out!

I appreciate this vehicle is not a proper shuttle replica, or cool looking like other submissions, however I feel it could be very valuable for people trying to create an asymmetrical craft; to use to understand the effects of changing centre of mass on the handling characteristics of a ship! If wanted the craft file can be posted!

 

[GRYPHUS-01]

10 hours ago, Alpha_Gametauri said:

Crap, i accidentally put a strut in there from KW Rocketry. Should i remove it and re-upload?

 

https://kerbalx.com/Alpha_Gametauri/Kerblantis/parts

Downloaded your craft just now. Dont worry i also use Kwrocketry

[GRYPHUS-01]

On 27-8-2017 at 4:11 AM, GRYPHUS-01 said:

Downloaded your craft just now. Dont worry i also use Kwrocketry

Okay so i took your model for a test drive, and honestly i dont know what flipping issue you have at reentry... i litterally just flew your shuttle 2 min ago into space, and aside from the bad balance between booster engines and shuttle engines in a space environment (due to you using canards for control during ascend and no angled shuttle engines) the thing flies decent. Nothing to do with its construction.

The 1st reentry i did with it was a succes and i landed your shuttle nice in some mountain land. Also during the reentry i watched the SAS axis corrections. seems your shuttle never reaches a max pitch/roll/yaw moment which indicates its balanced enough. If you flip over, are you trying to reenter at a AoA of 90°? if so thats your deathsentence. As you plummet downwards at a 90° vector. you have almost no airspeed in forward direction therefor all your wings do is create drag, but no control. That also counts for your hull resulting in a torque with no control from wings/controlsurfaces to counter and ultimatly a combination of "do a barrel roll" + "it's over 9000!"...

Anyway, try yourself but at an AoA of about 45-50° of Kerbin Horizon (navball). The real Shuttles lands with a AoA of about 90° from their Vector of Motion. But since its also travelling forward its not the same as 90° straight down. I think it's also about a 45° down. Therefor pitching 45° from horizon up result in its 90° vector for max drag while maintaining control. Easy, ain't it?

(Perhaps this might help?)

 

Edited August 29, 2017 by GRYPHUS-01
wrong term used, corrected

[Alpha_Gametauri]

On 8/26/2017 at 11:04 PM, GRYPHUS-01 said:

Okay so i took your model for a test drive, and honestly i dont know what flipping issue you have at reentry... i litterally just flew your shuttle 2 min ago into space, and aside from the bad balance between booster engines and shuttle engines in a space environment (due to you using canards for control during ascend and no angled shuttle engines) the thing flies decent. Nothing to do with its construction.

The 1st reentry i did with it was a succes and i landed your shuttle nice in some mountain land. Also during the reentry i watched the SAS axis corrections. seems your shuttle never reaches a max pitch/roll/yaw moment which indicates its balanced enough. If you flip over, are you trying to reenter at a AoA of 90°? if so thats your deathsentence. As you plummet downwards at a 90° vector. you have almost no airspeed in forward direction therefor all your wings do is create drag, but no control. That also counts for your hull resulting in a torque with no control from wings/controlsurfaces to counter and ultimatly a combination of "do a barrel roll" + "it's over 9000!"...

Anyway, try yourself but at an AoA of about 45-50° of Kerbin Horizon (navball). The real Shuttles lands with a AoA of about 90° from their Vector of Motion. But since its also travelling forward its not the same as 90° straight down. I think it's also about a 45° down. Therefor pitching 45° from horizon up result in its 90° vector for max drag while maintaining control. Easy, ain't it?

(Perhaps this might help?)

 

This is where i start getting confused. I re-enter at a 30' AoA, with my direction of travel is 10' below the horizon line. When i re-enter, the force required to keep it in a 30' AoA climbs as re-entry continues, and i either tumble and fly backwards into the ground, or flat-spin into it trying to fight the forces and keep it straight, even with RCS helping. Then when i adopted and straight in re-entry, components start to over-heat on re-entry and i explode about 28-23,000M in altitude.

 

Also take note this was my very first space shuttle design, my shuttle has many mods on it and this was a COMPLETELY stock version, but my tumble on re-entry problem still exists.

[AeroGav]

32 minutes ago, Alpha_Gametauri said:

This is where i start getting confused. I re-enter at a 30' AoA, with my direction of travel is 10' below the horizon line. When i re-enter, the force required to keep it in a 30' AoA climbs as re-entry continues, and i either tumble and fly backwards into the ground, or flat-spin into it trying to fight the forces and keep it straight, even with RCS helping. Then when i adopted and straight in re-entry, components start to over-heat on re-entry and i explode about 28-23,000M in altitude.

 

Also take note this was my very first space shuttle design, my shuttle has many mods on it and this was a COMPLETELY stock version, but my tumble on re-entry problem still exists.

I strongly recommend 

The graph it produces is really helpful -

If you look at the top one,  the horizontal axis represents your AoA and the vertical axis represents the pitching moment imparted by the aerodynamics of the craft in that situation.    What you want is a graph that always slopes "downhill" from left to right.   IE at negative AoA,  there is a pitching up tendency, which lessens as you get closer to prograde and at positive AoA a nose down tendency appears which gets stronger the further you get from prograde.   This helps to catch out airplanes that look stable according to the blue indicator but are only so because the canards are angled down a bit or the elevons are angled up a bit.    At high AoA, the surfaces at the back stall first and those at the front stall last, causing the craft to deep stall/swap ends.

A space shuttle lookalike has CG very far back, due to the weight of the vector engines.     There is a lot more fuselage in front of the CG than behind it and the stock blue indicator doesn't take into account fuselage lift.   So , this can result in the craft being unstable.    Also, most of the cargo bay is ahead of the CG so the shuttle can be unstable when unladen.

The engines of the real shuttle orbiter were much lighter relative to the weight of the vessel than they are in KSP, so it's CG was further forward.  Also the whole body of the orbiter was a lifting surface, so the centre of lift was further forward too.

Also,  in real aerodynamics the stalling angle of attack increases greatly at supersonic speeds.   Ferram Aerospace mod reflects this,  in the supersonic regime max lift occurs at 45 degree AoA or more.       In KSP it's 30 degrees in all conditions.     So the real shuttle didn't re-enter stalled,  but at an AoA a few degrees below max lift.     So maybe try coming in at 20-25 degrees tops.

Finally, look at what inputs SAS is making when trying to hold this nose-high attitude.    If your ship is aerodynamically stable,  you should see it making nose up inputs to try fight the tendency of the nose to drop.    If you see it making nose-down trim instead, watch out !  This means your craft is unstable.    The further the nose gets away from prograde,  and the deeper into the atmosphere you go, the more RCS will be needed to stop it flipping out. 

[Raptor9]

@AeroGav ninja-ed me while I was typing this, ha ha.

Players need to be careful when comparing KSP parts to their real-life counterparts.  The most often cited example is the fact that the Shuttle SRB's (in real-life) provided way more thrust then the Shuttle main engines, whereas the KSP versions it's just the opposite.

When you're comparing how the real-life Shuttle re-entered the atmosphere versus how any given shuttle design in KSP enters, keep in mind a few things.  First and foremost, the stock KSP atmospherics and aerodynamics models aren't completely accurate.  Second, to maintain aerodynamic stability when entering at extremely high angles-of-attack (ie above stall AoA), the center-of-mass and center-of-drag need to be fairly close to each other.  What does this mean exactly?

When an airfoil stalls, it's producing more drag than lift.  When airflow encounters a lifting surface at extreme AoA, like 90 degrees, the lifting surface is acting as an airbrake.  If you have a shuttle that has delta wings mounted on the back half of the fuselage, but the center-of-mass is in the middle of the fuselage length, the drag on the back half of the fuselage will cause the shuttle to "weathervane" into the direction of the oncoming airflow.  So you may want to make the tail heavier or move the wings forward.  However, this risks moving the center-of-lift forward as well, which risks making the shuttle unstable in forward flight or result in a tendency for the tail to "fall forward" during the reentry deceleration to make it unrecoverable.

Just with the ascent sequence, optimizing your shuttle's total airfoil solution is a balancing act between optimum glide performance and reentry stability & attitude control.  I prioritized glide performance first.  I try to keep a high AoA as long as possible during the reentry phase to create as much drag as possible (assisted with high-mounted airbrakes), but once the RCS and aero surfaces can't hold it, I stop fighting it and try to perform a series of gentle supersonic S-turns to bleed off more speed.  A lot of times the S-turns are unnecessary since I've already decelerated below 1400m/s by the time I hit the lower atmosphere and the heat becomes manageable anyway.

With my SSTO spaceplanes, which are large lifting bodies themselves in SR-71 style, I enter at 90 deg AoA at a much steeper reentry trajectory to use the entire underside as an airbrake.  By the time the air is thick enough that it snaps the nose back down in the weathervane effect, I'm already going slow enough not to overheat.

[AeroGav]

20 minutes ago, Raptor9 said:

Second, to maintain aerodynamic stability when entering at extremely high angles-of-attack (ie above stall AoA), the center-of-mass and center-of-drag need to be fairly close to each other.  

The way I like to explain it,  you still need to have positive aerodynamic stability - even after the fuel burns off, the cargo gets unloaded and even allowing for forces acting on fuselage parts - or the plane will want to flip out.      However, you can't have too much stability or it won't be possible to hold high AoA.    

For comparison, this is my "Baby Shuttle" re-entering from 300km

Note that

1. It has a much lighter engine package (and is very reliant on its SRBs as a result!).   One Poodle, 3 terrier, 3 puffs.   So the CG is pretty much dead centre of the cargo bay which means handling is the same laden/unladen.   Makes it much easier to strike the right balance between too much and not enough stability.

2. The wings have built in incidence angle of 5 degrees, so make lift at 5 degrees even when the body of the craft is following prograde.  Best glide ratio is found at this angle.

3.  The strakes are angled up a little more than 5 degrees, providing built in nose up trim so it holds prograde or just slightly above with no control input to the elevons.   This is important for glide performance, because the elevons raise the nose by pushing down on the tail, ie. by generating negative lift.   They create additional drag doing so, and because they are so close to CoM they have to press down pretty damn hard to get any effect.

4.  You can see a little dihedral for roll stability too.

5.  I'm adjusting my aim point by setting SAS to prograde when undershooting (best glide ratio) and raising the nose above optimum glide if the re-entry looks like overshooting.   You can see that the SAS is close to maxed out just holding the nose 10 degrees above the horizon.

6.  I've got cones clipped to the back of the engine nozzles to work around the open node drag problem. OK the final glide performance and landing distance are a little implausible.... but that's KSP aerodynamics!

 

5 minutes ago, AeroGav said:

OK the final glide performance and landing distance are a little implausible.... but that's KSP aerodynamics!

Actually, come to think of it, the gliding angle is actually very close to the real one.   Real world lift.drag ratios at subsonic speed are much better than possible in KSP.    

As for the touchdown and stop...  it would give a Fieseler Storch a run for it's money.  Not quite realistic !

[Alpha_Gametauri]

I went back to 1.2.2 until i get a stronger PC and FAR comes out. Harder to design a Shuttle in it for me, but when i get it right, it's a majesty.

[Andetch]

Heh, you really got me started on perfecting a shuttle design.... Re-entry is really easy once you get the hang of it and the build right, but tail-strike on landing is my biggest issue. I got my fleet sorted now, the shuttles can put x2 kerbals at a time onto either Min or Mun - by deploying their payload. Once carries a runner kit, the other a large fuel tank that is needed for Mun returns. 

Kerbal X: https://kerbalx.com/hangars/22952

I will release a demonstration video shortly.

[Andetch]

Andetch Shuttles Promo Video

 

 

[hurdurdur]

So my 160 science space shuttle has been waiting a long time to get on video, now it is. Nice little symmetrical space shuttle, not like the weird megatankered ones that NASA built.

 

[Thor Wotansen]

There's been a lot of talk on this thread about 'conventional' shuttles, but I noticed the SSTO bit in the title and had to drop by.  One of my favorite SSTOs is the Róta.  I designed it to haul a full Rockomax Jumbo 64 tank (big orange) to an 80km orbit, and it has surpassed that mark, albeit only slightly.  The design is such that the COM doesn't change with fuel or payload loading and I built a 15 degree incidence into the wing to improve drag characteristics for both ascent and descent.  This also has the added benefit of lower takeoff and landing speeds, and higher controlability at low speeds.  What Raptor9 and AeroGav have said about KSP reentry mechanics holds just as true for an SSTO as for a shuttle, and having the COM and the COL properly positioned at all fuel and payload loadings really does make or break the flyablility of a craft.

[KerbalTween]

On 8/16/2017 at 4:22 PM, NSEP said:

I honestly prefer a dreamchaser like spacecraft doing a regular in-fairing launch than a 70 ton brick glider slapped right next to a rocket. Its much easier to build. Also, a Maks type system is also quite neat, bassicly a small shuttle launched from a plane with a big fuel tank.

My Saying `Weak People Choose Dream Chaser Over The Harder American Space Shuttle`

[KerbalTween]

And Btw This Is My Shuttle that am using currently for Sat launchs Atlantis https://imgur.com/a/a3wuC It can Land And I Will Put Up the Ability to get this craft Recommended Mods are AA Mods Used Is Procederal Parts and Kw Booster and If You Have Stage recovery the Boosters will recover It Can Land Because I Clipped Tanks In the front And One In the back To Balance It Out It Lands greatly If You have the skills And Its stable at Launch and Landing Low torque Is responisble for that Like Only 10 torque for This Config with the sat One danger I Noticed If You don`t Let Your Shuttle On the Top of the Orange Tank At 40m It will Not be Very stable And Mechjeb Manuvers and Normal Are don`t work the best P.S Has rudder Tail

 

Edited October 22, 2017 by KerbalTween

[NSEP]

5 hours ago, Kerbal Tween said:

My Saying `Weak People Choose Dream Chaser Over The Harder American Space Shuttle`

My saying: Experienced people choose Dream Chaser because they already built the space shuttle and realize its too bogus for its job.

Don't judge a book by its cover!

By the way Buran>Shuttle.

Edited October 22, 2017 by NSEP

[AeroGav]

For some time I've been telling people that if you don't want to go pure SSTO,  rocket launched shuttle is not the only way.      Jet boosters are also a possibility and in my opinion,  easier, more elegant and less wasteful  (fewer parts end up in the ocean).      But,   this message works better with examples.      So,   I took the rocket launched stock Learstar craft and made it into a jet boosted MSSTO (Mostly Single Stage To Orbit).       

https://kerbalx.com/AeroGav/Learstar-A2

Here is the stock Learstar, for those that haven't had the pleasure 

 And here is my version, with the booster jets

The crew and cargo capabilities are the same. 

Is there  a proper term for this kind of vessel?    It's not really a Space Shuttle (uses air breathers, discarded hardware is less than 15% of launch mass),  but it's not an SSTO  either..

[selfish_meme]

4 hours ago, AeroGav said:

For some time I've been telling people that if you don't want to go pure SSTO,  rocket launched shuttle is not the only way.      Jet boosters are also a possibility and in my opinion,  easier, more elegant and less wasteful  (fewer parts end up in the ocean).      But,   this message works better with examples.      So,   I took the rocket launched stock Learstar craft and made it into a jet boosted MSSTO (Mostly Single Stage To Orbit).       

Is there  a proper term for this kind of vessel?    It's not really a Space Shuttle (uses air breathers, discarded hardware is less than 15% of launch mass),  but it's not an SSTO  either..

I'm not sure, my shuttle SSTO hybrid uses Rapiers on the shuttle part, so can SSTO from Laythe

[A Soviet Tank]

I made a really tiny shuttle a while ago. (modded as hell) I used it to transfer experiments and crew between Kerbin and my Minmus base.

https://i.imgur.com/yjpLfut.png

I don't have a picture of the launch stage, but it was pretty much a mainsail and a couple kickback SRBs. The shuttle was mounted on the very top of the launch stage, not on the side.

[53miner53]

On 10/22/2017 at 3:29 AM, NSEP said:

My saying: Experienced people choose Dream Chaser because they already built the space shuttle and realize its too bogus for its job.

My saying: Crazy people build a 160t orbiter, and build a lifter that makes it able to lift 160t payloads! 

[AeroGav]

Here's another space plane that discards its jet engines.     By definition,  it is not an SSTO, so I guess i belongs in this thread rather than the SSTO one.

I have been developing Spaceplanes for a rescaled Kerbin system.      I'm using a rescale factor of 3.2  which is the same as @eloquentJane is using in her career save.       This greatly increases the difficulty, since orbital velocity is now mach 14 as opposed to the mach 7 or so you get in stock KSP.    But still not as hard as real life, orbital velocity mach 21 !

Also note, the atmosphere is scaled up by 40% too.   28km with rescale is more like 20km in stock atmo,  and the boundary of space is 98km.

I managed to get into orbit with a 7 seat SSTO here 

but it only had 400dV left over in a 110km orbit, which would make rendezvous slow.

The Whiplash-discarding version only has 5 seats,  but it does have 55 units of oxidizer and a full vernier rcs system for docking, and reached a higher 125km with over 1400dV remaining,   so is probably more usable.    These whiplash engines only cost 2200 funds each, so compared to the value of the discarded external tanks and boosters of an STS style system (especially, the monstrous type of one that could launch a shuttle on rescaled Kerbin)  this is not too bad.

 

https://www.dropbox.com/s/v3enet77pm1jl5i/Starion2.craft?dl=0

[Guerra]

So you say you like launched space shuttles huh?

Edited November 21, 2017 by Guerra

[septemberWaves]

@Guerra That has got to be one of the strangest shuttle designs I've ever seen. Very nice.