Space Shuttle Balance(key point is wing?)

[xxxwxl]

Q1:The decoupler can't hold solid fuel booster.

I used TT-38K to combine S2-17 solid boosters with Kerbodyne S3-14440 Tank.Then  boosters run away alone.Is the force too huge?

https://thumbsnap.com/f/gWXDGEoM

https://thumbsnap.com/f/KyguLA5o

Q2:Balance

So I changed my mind,put shuttle on the top of rocket.But it became unstable because of  aerodynamic force on the wings.

https://thumbsnap.com/f/tBFxZxB1

https://thumbsnap.com/f/eyyiF2J6

How to make a shuttle stable?

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With Rhomphaia's help,I didi it.

Then I did a experiment.Builded a total symmetrical vessle without wheels and tail fin,lauched it, failed.

I put the COT on the COM.It failed too.And even worse,it could't reach 2km.

https://thumbsnap.com/f/LwX15oVt

At last,I removed the wings.

The first design got into 70km orbit smoothly.The second design reached 20km, then lost balance.

It seems like the key point is wing.But,why?It is symmetrical. What can I do to deal with the aerodynamic force on the wing?

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Finally,I kown the key is Force Balance.What's i need is another Big-S Wing.The lower wing take force to balance the upper wing.

THX for all.

https://thumbsnap.com/f/FEagkSP9

 

 

 

 

 

Edited June 12, 2020 by xxxwxl

[Rhomphaia]

For the first I think the problem comes from "rigid attachment on", while it makes joins less wobbly, it does make them brittle, if they cant bend, they break.

Best for boosters to use "Autostrut to grandparent part"

[xxxwxl]

23 minutes ago, Rhomphaia said:

For the first I think the problem comes from "rigid attachment on", while it makes joins less wobbly, it does make them brittle, if they cant bend, they break.

Best for boosters to use "Autostrut to grandparent part"

Thank you very much! I did it!

https://thumbsnap.com/f/4pSD7NV3

[Spricigo]

Check your staging sequence. Looks like the engines just snap the craft from the not released Launch Stability Enhancer with the decouplers failing just before. 

Unstable Shuttle? ... that's an old recurring topic around here. 

The basic advice is:heavy stuff in front, drag stuff at back, thrust aligned with CoM at all times and control surfaces with enough leverage to actually work. 

 

[xxxwxl]

11 hours ago, Spricigo said:

The basic advice is:heavy stuff in front, drag stuff at back, thrust aligned with CoM at all times and control surfaces with enough leverage to actually work. 

 

I did a experiment,builded a total symmetrical vessle without wheels and tail fin,lauched it, failed.

Then I put the COT on the COM.It failed too.And even worse,it could't reach 2km.

https://thumbsnap.com/f/LwX15oVt

At last,I removed the wings.

The first design got into 70km orbit smoothly.The second design reached 20km, then lost balance.

It seems like the key point is wing.But,why?What can I do to deal with the wing?

 

[Spricigo]

1 hour ago, xxxwxl said:

It seems like the key point is wing.But,why?What can I do to deal with the wing?

Because those wings probably are the draggiest stuff there, the kind of stuff you want to put down at the very bottom. ... but then you have to figure out how to place the boosters in a way that keep you CoM at least within gimbal range of the line of thrust... and still avoid other shuttle lookalike design traps. 

 

 

 

[TheFlyingKerman]

The main problem with the design is with those blunt faces. This causes much drag in front. You should put 2.5m to MK3 adapters between the MK-1-3 pod and the crew cabin, also the MK3 fuel tank and engine, to smooth the profile. Then the problem with the wing is that it has no movable control surfaces, so the big wing would not help your re-rentry either. At least, put fins at the bottom so that the COL is way behind the COM.