Trebucket, It's pronounced bouquet

[Moesly_Armlis]

 

The trebuchet was something I never built before.  A pivot point seemed to be missing.  The first attempt used launch clamps and a whole lot of struts.  While it did function problems were stability and transportation.

Started searching for bearing and most involved wheels and now with 1.1 those ideas seemed unlikely.

  @Majorjim thread

was the idea for using thermometers and which now had inspired me to push further.  The need for a pivot that could handle hundreds of tonnes of mass started me to ponder on using different parts.  After shopping through the part list it was staring right at me. The structural fuselage.  Now to find a suitable pin for the sleeve.  The choice was the Modular Girder XL.

 + = AWESOME!

The sleeve is attached temporarily to the girder using a stack separator.  Then using the translation tool to place in into position.  Once in the field the separators are staged and there are now two separate craft.

 

This was the first version that functioned.

 

The Ion plane Research Challenge was were it all began.

 

Go for broke edition.

 

Animated gif of functioning glider launcher.

http://i.imgur.com/iYac5ZR.gifv

 

For the longest time during this process it seemed the trebuchet was ordered from the acme parts catalog and I would hear meep-meep as another failure happened.

So here another chapter begins.  The creation of a functioning trebuchet.  It will be portable, re-settable and be able to chunkin pumkin.

 

 

This thread can also be for further research into using this pin and sleeve bearing.  As you can tell this bearing can support some mass and the uses of a proper bearing are countless.

 

Edited May 5, 2016 by MoeslyArmlis

[Moesly_Armlis]

Been improving the design and having too much fun.

Here is the craft file.

File to edit Trebuchet Ion Glider.

File to just launch, already positioned.

 

Warranty void if unpackaged.

Edited May 5, 2016 by MoeslyArmlis

[Majorjim!]

That is absolutely extraordinary! 

 It was amazing to watch it in motion man. Nice work!

[esinohio]

This is just great!  Wondering just long it will be for the first Kerbal flinging video to appear using this device.  

[pTrevTrevs]

You might want to take a look at mine: 

The bearings aren't fancy, but they work and don't add to many parts. It's got a working hinge and a sling (although it requires KAS). It can launch a Stayputnik probe core several hundred meters.

Edited May 5, 2016 by pTrevTrevs

[Moesly_Armlis]

17 minutes ago, pTrevTrevs said:

The bearings aren't fancy, but they work and don't add to many parts. It's got a working hinge and a sling (although it requires KAS). It can launch a Stayputnik probe core several hundred meters.

I was checking out what you have done earlier, very impressed and was ready to give up on stock  Would you want to convert yours to stock?  Place it here.

Had never used this structural fuselage part ever before and was not sure that placing parts inside would not summon the kraken.

Can some one check and see if this is possible in 1.0.5

[katateochi]

That is very cool Sir!
A long long time ago I made a thing that I called a trebuchet, someone corrected me, saying that it was infact a mere catapult, by hey, it flung Kerbals and that's all I cared about!  Yours is considerably more impressive in design and uses a more conventional approach (mine used engine thrust as the "counter weight"). And you launch a glider with it! That's very cool.
anyway, here's my ancient vid if you're interested

[GoSlash27]

Or as we called it, the "tree- bucket"

A few years back, squirrel launcher videos were all the rage. I got the idea to build the ultimate squirrel launcher (don't worry, no *actual* squirrels were harmed in the process).

I designed and (with the aid of a few friends and copious amounts of beer) built the "tree- bucket"; a floating axle trebuchet that used a bucket to fling the critters into a tree down the block.

There's a series of videos on Facebook covering the design, assembly, and testing, but no way to share it here. Good times... It ended up being horrifying how far the thing would fling a "squirrel simulant", so we wisely decided to scrap the project.

*edit* Here's some really crappy frame stills from one of the videos:

http://s52.photobucket.com/user/GoSlash27/slideshow/Tree-%20bucket?sort=9

Here's a video of a floating arm trebuchet in action. Food for thought?

Best,
-Slashy

Edited May 6, 2016 by GoSlash27

[Moesly_Armlis]

1 hour ago, The_Rocketeer said:

I enjoyed watching this.

You're right about the counter-weight pivot, but actually I think for better results you want a second pivot in the throwing arm (labelled 'Sling' below - not my artwork).



 

This is interesting.  My experiments led me to use the flex that are on each part.  The longer "kickbacks" make for stiffer sections , the "thumper" for mid flex then the girders for the most flex.

The three point pivot should make for some interesting engineering.

2 hours ago, esinohio said:

This is just great!  Wondering just long it will be for the first Kerbal flinging video to appear using this device.  

As long as no kerbals are hurt I totally approve. 

Plus I am about to finish off a design for kerbals to ride inside, called the "Bueller".  The design has a feature based on another experiment performed with the new bearing.

 

[pTrevTrevs]

2 hours ago, MoeslyArmlis said:

I was checking out what you have done earlier, very impressed and was ready to give up on stock  Would you want to convert yours to stock?  Place it here.

Had never used this structural fuselage part ever before and was not sure that placing parts inside would not summon the kraken.

Can some one check and see if this is possible in 1.0.5

Unfortunately a stock trebuchet simply will not perform as well as a modded one. I tried to keep it as mod free as possible (even the finished version only has two modded parts, only onw of which is actually on the machine itself). You may consider the extra features such as the counterweight hinge and sling as frivolous, unnecessary, or simply not worth the effort, but they are essential parts to making the most efficient trebuchet possible. The hinge relieves stress on the throwing arm and reduces the amount of energy wasted overcoming the weight's inertia. The sling is possibly even more important, as it transfers as much energy as possible to the projectile itself, increases the velocity of the projectile at the time of release, and allows you to release the projectile at just the right time, allowing for the desired release angle and maximum velocity. Real trebuchets need slings because that's the most efficient way to get a reliable, consistent release without using some sort of computer or having a person pull a trigger.

The beautiful part about building trebuchets is that the ideal length and weight ratios have already been figured out. Trebs have been around since the 4th century BC (in the form of the traction trebuchet) in China, and I think they came to Western Europe around the 1100s AD (also around the time counterwight trebuchets were invented). Considering how widely there were used, it only makes sense for their construction to have been narrowed down to a science. Once you figure it out, it's pretty easy to repeat it.

Sorry for the long post to answer such a short question, but if you're going to build a trebuchet, you'll want know the reasons for the different parts of one.

[Moesly_Armlis]

The title refers to a show my nurse watches.  When she was reading trebuchet to me she so cutely said tree bucket.  Laughing and the first thing that popped in my mind was "it's pronounced bouquet".  I immediately replied, trying to mimic Hyacinth.  Then my lovely nurse just laughed.

 

Here are some images of the bearing assembly.

 

 

Currently been testing the bearing by stressing angular momentum.  It cranks very fast and stable.  Keep in mind testing has only been in the horizontal placement.

 

Was this bearing style able to function back in 1.0.5?

Is this magic?

Did the change over to Unity5 open up this bearing possibility?

 

What name should it have?

Pin and sleeve is how I have been referring to it.

 

@pTrevTrevs Thanks for that explanation.  My siege warfare experience within a computer sim was back a few years ago and that was the closest I have ever been to this style of equipment.

[pTrevTrevs]

In case you were wondering, the ratios I typically use when building a trebuchet are as follows:

Throwing arm length/counterweight arm: 5:1 (although I've heard that 4:1 is also used)

Projectile weight/counterweight... weight(?): 1:133. Sounds like a lot, but if you clip a bunch of ore tanks or fuel tanks together you can get that ratio or an even greater one.

Sling length: 80% of throwing arm length. There are other small things you can do like adding wheels to allow the entire frame to rock back and forth as the counterweight swings, it further negates any energy wasted in fighting inertia.

[Moesly_Armlis]

On 5/6/2016 at 11:54 PM, pTrevTrevs said:

In case you were wondering, the ratios I typically use when building a trebuchet are as follows:

Throwing arm length/counterweight arm: 5:1 (although I've heard that 4:1 is also used)

Projectile weight/counterweight... weight(?): 1:133. Sounds like a lot, but if you clip a bunch of ore tanks or fuel tanks together you can get that ratio or an even greater one.

Sling length: 80% of throwing arm length. There are other small things you can do like adding wheels to allow the entire frame to rock back and forth as the counterweight swings, it further negates any energy wasted in fighting inertia.

That is some very under clear guidelines.  Thanks.  Having more than one pivot point was tackled.  Also maximum torque has to be further investigated.

 

The multi point rotation was up for examination and testing went well.

 

However, now there is a Bueller on the tarmac.

 

 

Here is the craft file.

Bueller

Warranty void if used with kerbals.

Edited May 7, 2016 by MoeslyArmlis

[Moesly_Armlis]

The idea of a a square peg rotating in a round hole seems to just grind my gears a little.

 

The potential parts that need investigation for pin and sleeve combinations. 

I am about to try the MK0 Fuel tank and the Structural Fuselage. Reports will follow.

[Moesly_Armlis]

Bearings are not Borings

 

This has the MK0 fuel tank and an adapter for smooth operation.

RPM = not slow.  Best guess over 2400 revs. Smooth and not jittery like the girder was.  The focus should have been on the command chair and then the RPM could have been determined.  The panels are deforming and separating at high RPM.

 

Craft File

Not recommended for kerabal attachment.

Bueller Smooth

 

Considering the part potentials; the MK1 Command pod and the structural fuselage are next for testing.  These parts might provide omnidirectional operation with higher impact tolerances.

Edited May 6, 2016 by MoeslyArmlis

[Moesly_Armlis]

Trying to improve the bearing by increasing the diameter of the pin.  Results were terrible.  The pin being closer to the sleeve would pop out of the Structural Fuselage and rotation almost would stop.  The wobbles then would be next and the whole thing is then a mess.

Having the contact point smaller than the sleeve is the best so far.

 

The free style counter weight was tested.

 

This did not use any of @pTrevTrevs advice and since the testing went well the next build should have more of those fine details.