Welcome, Guest. Please Login
SLINGING.ORG
 
Home Help Search Login


Page Index Toggle Pages: 1
Send Topic Print
New trebuchet (Read 4408 times)
HurlinThom
Interfector Viris Spurii
*****
Offline


Leverage artillerist

Posts: 1458
New trebuchet
Jun 23rd, 2011 at 11:52am
 
Built a half-size prototype of one I intend to enter in this Fall's pumpkin event at Cal State Fullerton. Finished the frame yesterday, fitted it with an existing arm, sling, and counterweight to test for function. Here's a still from the video I shot. Performance was not great, but the working parts were pretty mismatched.

If the wood seems assorted, it is. I used a bunch of boards that had been sitting around taking up space, some out in the weather.
Back to top
 

MVI_2064.jpg (56 KB | )
MVI_2064.jpg

When all is said and done more will have been said than done.
 
IP Logged
 
Bill Skinner
Forum Moderation
*****
Offline


Slinging Rocks!

Posts: 3292
Re: New trebuchet
Reply #1 - Jun 23rd, 2011 at 8:35pm
 
Looks like a neat job to me.  Do the neighbors ever complain?  Bill
Back to top
 
 
IP Logged
 
HurlinThom
Interfector Viris Spurii
*****
Offline


Leverage artillerist

Posts: 1458
Re: New trebuchet
Reply #2 - Jun 23rd, 2011 at 10:49pm
 
Thanks. Bill. All angles and lengths were calculated pretty carefully, and cut as precisely as I could. I'm trying to make this one as close to half the big one as I can, within the bounds of practicality. This one is for practice, to make sure the calculations are valid. I really don't want unpleasant surprises when I get the 2X6s I actually paid for cut.

No neighbor complaints, but they're mostly pretty cool. I limit myself to tennis balls so no real damage gets done.

BTW, I made a couple of minor changes and increased throwing distance around 40%.
Back to top
 

When all is said and done more will have been said than done.
 
IP Logged
 
Masiakasaurus
Forum Moderation
*****
Offline


mah-SEE-a-kah-SOR-us

Posts: 6069
Alabama, USA
Gender: male
Re: New trebuchet
Reply #3 - Jun 24th, 2011 at 10:31am
 
HurlinThom wrote on Jun 23rd, 2011 at 10:49pm:
BTW, I made a couple of minor changes and increased throwing distance around 40%.

What were the before and after distances?
Back to top
 

Pikåru wrote on Nov 19th, 2013 at 6:59pm:
Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. 
~Engineers like to solve problems. If there are no problems handily avialable, they will create their own problems.~
WWW elsabio04  
IP Logged
 
HurlinThom
Interfector Viris Spurii
*****
Offline


Leverage artillerist

Posts: 1458
Re: New trebuchet
Reply #4 - Jun 24th, 2011 at 10:52am
 
Guesstimated 80 feet to indirectly paced-off 115.  Wink First shot hit my roof short of the ridge, second one was recovered in the jasmine ground cover in the front yard. The greater distance might have been impeded by a small tree, but bounce and roll are unlikely. Both release angle and velocity were visibly better on the later throws.

Might not sound like much distance but the frame is barely over 2 1/2 feet tall, and nothing "trick" has been tried yet.
Back to top
 

When all is said and done more will have been said than done.
 
IP Logged
 
Bill Skinner
Forum Moderation
*****
Offline


Slinging Rocks!

Posts: 3292
Re: New trebuchet
Reply #5 - Jun 24th, 2011 at 12:00pm
 
Where do you go to test fire? If your treb is like a sling, your ammo limits your range, which can be a good thing, but don't you really want to know what it is capable of doing?  Bill
Back to top
 
 
IP Logged
 
HurlinThom
Interfector Viris Spurii
*****
Offline


Leverage artillerist

Posts: 1458
Re: New trebuchet
Reply #6 - Jun 24th, 2011 at 12:19pm
 
Well, there's a park I go to, but I have to wait until the off-leash dogs clear out. Legally the dogs ought to be on-leash, but that's ignored. Since most of my trebs are small I can use the back yard for early development. I have around 130 feet to play with before things exit my yard. The better efforts do wind up on the lawn across the street. I may have hit that house on occasion, but tennis balls have almost no energy left after traveling that far. As I find more ways to increase performance I build smaller to avoid problems/confrontations.

Just stuck a video up on YouTube, for those who are interested.

http://www.youtube.com/watch?v=LP5yq45nO_A
Back to top
 

When all is said and done more will have been said than done.
 
IP Logged
 
Curious Aardvark
Forum Moderation
*****
Offline


Taller than the average
Dwarf

Posts: 13965
Midlands England
Gender: male
Re: New trebuchet
Reply #7 - Jun 24th, 2011 at 1:13pm
 
Quote:
but I have to wait until the off-leash dogs clear out.


lol you miss a trick there - just get the dogs to bring the balls back Smiley

like the video too.

So what weight you got on that ?
Back to top
 

Do All things with Honour and Generosity: Regret Nothing, Envy None, Apologise Seldom and Bow your head to No One  - works for me Smiley
 
IP Logged
 
Morphy
Slinging.org Moderator
*****
Offline


Checkmate

Posts: 8102
Re: New trebuchet
Reply #8 - Jun 24th, 2011 at 5:16pm
 
Maybe I'm looking too far into this but it seems like the treb's arm in the picture is about the same length as the sling portion? Is that correct and is there a certain golden ratio that lets you know the most efficient length for each in proportion to one another?
Back to top
 
 
IP Logged
 
HurlinThom
Interfector Viris Spurii
*****
Offline


Leverage artillerist

Posts: 1458
Re: New trebuchet
Reply #9 - Jun 24th, 2011 at 6:10pm
 
Morphy, the golden ratio is whatever works best. In other words it's situational. If the arm is fast (light, low moment of inertia, light projectile, or heavy counterweight) it sling needs to be shorter. And a longer sling goes with a slower arm. You're trying to get sling release at the point where as much of the energy as possible has transferred from the falling counterweight into the ball. There's some disagreement as to the particulars, and it's likely really a boring subject unless you're actually trying to optimize a treb's tuning.

CA, that's 20 pounds (iron, not Stirling). About 9 kg to those in the modern world. Plus a couple for the attaching gubbins. Matsu isn't much of a tennis ball chaser. Can't be bothered with piddly little stuff like that. As a youngster she did try to catch a Saluki, pretty amazing; they circled the park a few times until the Saluki kicked in the afterburners and left her. That's supposed to be the fastest breed in the world.

Ah, you meant the dogs in the park. Dog slobber all over my nice tennis balls? I think not. Plus they'd "fetch" the balls to their owners, not to me. 
Back to top
 

When all is said and done more will have been said than done.
 
IP Logged
 
Masiakasaurus
Forum Moderation
*****
Offline


mah-SEE-a-kah-SOR-us

Posts: 6069
Alabama, USA
Gender: male
Weapon of Medi(a)eval destruction
Reply #10 - Jul 26th, 2012 at 12:54pm
 
Off topic replies have been moved to This Thread
Back to top
 

Pikåru wrote on Nov 19th, 2013 at 6:59pm:
Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. 
~Engineers like to solve problems. If there are no problems handily avialable, they will create their own problems.~
WWW elsabio04  
IP Logged
 
ChuckRocks
Senior Member
****
Offline


Leverage Artillery Design
Engineer

Posts: 292
The Florida Outback, USA
Gender: male
Re: New trebuchet
Reply #11 - Jul 29th, 2012 at 9:06am
 
HurlinThom wrote on Jun 23rd, 2011 at 10:49pm:
No neighbor complaints, but they're mostly pretty cool. I limit myself to tennis balls so no real damage gets done.


They don't dare.
They all think he's one of the Capitol One Vikings.
Back to top
 

(AKA Walker / Visit my Facebook page: at http://www.facebook.com/pages/SiegeMasters/168138883205859 )
WWW  
IP Logged
 
xxkid123
Past Moderator
*
Offline


Hallo, ich heiße kartoffel

Posts: 4807
new to california
Gender: male
Re: New trebuchet
Reply #12 - Jul 31st, 2012 at 6:40pm
 
ChuckRocks wrote on Jul 29th, 2012 at 9:06am:
HurlinThom wrote on Jun 23rd, 2011 at 10:49pm:
No neighbor complaints, but they're mostly pretty cool. I limit myself to tennis balls so no real damage gets done.


They don't dare.
They all think he's one of the Capitol One Vikings.


Grin
Back to top
 

There's no break, there's no end, just a-living on;&&Wide awake, with a smile, going on and on.
xxkid123 tanma101  
IP Logged
 
HurlinThom
Interfector Viris Spurii
*****
Offline


Leverage artillerist

Posts: 1458
Re: New trebuchet
Reply #13 - Oct 20th, 2012 at 2:48pm
 
Little update on the small one. I just finished a very light arm (using up some materials that were taking up space in the shop) and put a small video of an ealy shot up on You Tube.

http://youtu.be/diml-21PIY0
Back to top
 

When all is said and done more will have been said than done.
 
IP Logged
 
Page Index Toggle Pages: 1
Send Topic Print
(Moderators: Bill Skinner, Curious Aardvark, Rat Man, Chris, Masiakasaurus, David Morningstar, Mauro Fiorentini)