Build an Assymetric SSTO!

[Heretic391]

Asymmetric aircraft's are fascinating so build an ssto out of it! I intend to try this myself one day as it's interesting. 

 

Noob level: Make it fly.

Bob level: Create an orbit around Kerbin. 

Jeb level: Land on the Mun.

Val level: Land on the Mun then return to Kerbin.

 

Here is a real life assymetric airplane for reference Blohm & Voss BV 141.

 

[Vanamonde]

I'd have to be able to build a symmetrical one, first.

[Racescort666]

Ah, asymmetric aircraft, here's a good one:

 

I'm interested to see what people might come up with for this.

[Heretic391]

Would love that, but is it confirmed that we will be getting propellers in KSP 2? 

[Syvwlch]

Here's my entry for the Bob level (flown by Bill, oops):

Wheels up

Saying goodbye to the KSC

Mode switch altitude and speed

Coasting to apoapsis

Circularization

Barely made it but it counts!

Note I have waaaaay too much methane on board, so can probably improve the dV in LKO by just leaving 3 tons of CH4 at the KSC... but not enough to attempt the Jeb level challenge.

[GalileOh-No]

Now you have to balance it by putting a payload on the other side!

[Syvwlch]

  

2 hours ago, GalileOh-No said:

Now you have to balance it by putting a payload on the other side!

Nooooo! 

Edited April 15, 2023 by Syvwlch

[Syvwlch]

After a little bit of tweaking and adding some more methalox tanks, got to 1km/s dV remaining in 80x80 LKO:

That main fuselage is starting to look ridiculously long and you have to baby it a little more off the runway, but still flies very sedately.

[GalileOh-No]

Some questions for my edification (I am worse with planes than I am with rockets):

Is the side tank radially attached to the fuselage and simply offset?

Did you have to adjust the side tank's thrust off parallel with the main or are you able to balance the yaw with drag only (different size wings, etc)?

Gimbal lock, control axis editing at all?

When do you plan on flying that thing under a bridge?

[Syvwlch]

Yup, the outboard pod is radially attached and then moved into position. 

All three Rapiers are parallel to main fuselage, but the thrust limiter on the outboard one is adjusted down to move the position of the thrust vector in line with CoG. The various wings are sized and placed such that the CoL is also in line, and only slightly aft of the CoG.

Main difficulty is finding a fuel tank layout that does not move the CoG as either fuel type drains (methalox and methane). I basically laid it out so the outboard pod has 1/2 the number of tanks and roughly half the dry mass to keep things simple. As fuel drains the ratio of the vehicle's mass in either part stays the same and the COG doesn't move .

The only control surface tweaking is reducing the authority to keep SAS from oscillating which at best is inefficient but usually results in a tumble and explosion. 

Edited April 15, 2023 by Syvwlch
Clarified that the dry mass ratio is also 2:1 between fuse and pod.

[Syvwlch]

Jeb level entry - Landed an Asymmetric SSTO on the Mun!

Again, barely made it (definitely don't have enough to get back to orbit) but it counts... Elbas volunteered, I swear!  

Here are (large) screenshots showing we started with 2km/s dV in LKO and where we landed with less than 100m/s dV left:

Spoiler

This is a complete rebuild from scratch, using some larger methalox tanks as a starting point:

Here's our target!

Caught a weird double intercept but since we captured on the first pass, it remained theoretical.

Looked at the planned landing spot from orbit before initiating descent.

Caught Kerbinrise on our way down!

I managed to get one screenshot during the actual landing because I was rather busy with the usual SSTO vacuum landing: zero velocity relative to ground a few meters up, and pitch nose down to land on gear. 

[Heretic391]

On 4/17/2023 at 8:36 AM, Syvwlch said:

Jeb level entry - Landed an Asymmetric SSTO on the Mun!

Again, barely made it (definitely don't have enough to get back to orbit) but it counts... Elbas volunteered, I swear!  

Here are (large) screenshots showing we started with 2km/s dV in LKO and where we landed with less than 100m/s dV left:

  Hide contents

This is a complete rebuild from scratch, using some larger methalox tanks as a starting point:

Here's our target!

Caught a weird double intercept but since we captured on the first pass, it remained theoretical.

Looked at the planned landing spot from orbit before initiating descent.

Caught Kerbinrise on our way down!

I managed to get one screenshot during the actual landing because I was rather busy with the usual SSTO vacuum landing: zero velocity relative to ground a few meters up, and pitch nose down to land on gear. 

Wow great job!  How long did it take for testing? 

[Syvwlch]

Thank you!

Going by the name of the craft the eighth launch is the one that made it to the Mun. Took maybe a day of off and on tinkering?

The tweak it took me a while to realize I needed to do was sizing the two canards so that they did not induce a roll when used to raise/lower the nose, especially on takeoff. Wasted some time believing it was a thrust imbalance.

Edited April 28, 2023 by Syvwlch

[Heretic391]

This was actually a fun build:  https://kspbuilds.com/build/Assymetric-Spaceplane-v22-+-Secret-Rover

The only problem is once we consume fuel, its a big guessing game on where the COM is at... Also, if anyone wants to build one, you'll have some trouble with the game being confused about symmetric part placement.

Stats:

DV: 10,000

Parts: 340

Total Mass: 250t

[Real rocket manufacturer]

POV: Noob

 

I'm just adding a radial parachute on the other side!