Reads with Scotch ’s Comments (group member since Mar 14, 2008)

Reads with Scotch ’s comments from the Axis Mundi X group.

I can see an eye injury coming from your suggestion Charissa.

Are you having trouble sleeping at night? I think it is because you know I am here all alone, desperate for conversation, but that’s ok Charissa, stay in your comfortable bed. I don't mind. I have plenty of math to do.

I wish I could play an instrument... I couldn't hold a note or carry a tune in a bucket however {:-/

My wife is tiny, 5’1 maybe 5’2 if she stands on a book. At any rate, our goodie cupboard is above the fridge… Don’t ask me why, I think my wife just likes to boss me around to get her goodies… One day I was outside working on a project that wasn’t a trebuchet and I hear her yelling like her life is about to end, So Being the alpha male type I run inside with my manly post digger ready to rain down some pain on whatever/whoever is causing my wife distress. What do I find when I get inside? She is half on the counter, one hand on top of the refrigerator one foot on the floor, and the rest of her somehow wedged between the counter and fridge… women, you guys are hysterical and adorable all at the same time.

I knew that cartoon was lying to me.

I will close my back to back postings with this. My brain is completely fried now, after 3 intensive hours being submerged in physics and math that I have not seriously used in years. I think I pulled something, I don’t feel right. I need to go back to work, and do some mindless menial task for a couple of days. Remind me on wed, not to over do this again when I get home and can unleash my full intellect and resources against this problem of physics.

Johnny I will require your feedback from time to time, so you may want to conduct some small scale building of your own… this project has a lot of potential of inflicting serious injury should any mistake/accident occur.

I have discovered this evening that trebuchets, are not vary practical for ridding one self of an old car or pesky neighbor. The size of the equipment is just too large in relation to the size of the projectile. What did I expect from technology from 400 B.C.? I am still going to build many of them, and have some real plans in place for "Big Bertha" in the summer of ’09.

I will start small and work my way up to a size that can safely launch no less then a 300lb object at lest 300 meters. This should be manageable. Large, scary looking to my neighbors, and really fun to play with.

http://www.algobeautytreb.com/

http://heim.ifi.uio.no/oddharry/blide...

I can't access youtube from my work computer. I'll check it out when I get home... 4 days woot!

Johnny, I am swimming... then I got sidetrack on this extremely interesting discussion on launching spacecraft from trebuchets, then on to balloons. Check it out if you’re interested

http://forums.seds.org/archive/index....

Am I showing my inner geek?

http://www.ripcord.ws/theory.html : Ok after further research and some more math, I now know that throwing the Bx van is beyond my capabilities, even by next summer. Heavy heart. So I think scaling back our projectiles to 300 lb we should be able to achieve a couple hundred meters no problem. The trick is maintaining structure integrity, and maintaining 600 fps for at lest 2 seconds after launch. This will be a lot harder then it sounds.


Found this in a discussion group about the physics of trebuchets:

I think it would be most beneficial for unmanned operations to use the ballista idea, or a giant electromagnetic crossbow. If we built a 20km track that could accelerate a shuttle at say 5G's, we are looking ab mach 4.1 at the end of the track. 40km track and we get mach 5.8. Even if it is only 17% of earth's escape velocity, it is a dramatic improvement over what we are looking at now.

Just out of curiosity's sake, what would happen if we could accelerate that load at 8G's? The 20km track would hit mach 5.1, and the 40km track would hit mach 7.5. Now we are looking at 23% of escape velocity, and if we had the track at an angle, we could be looking at even more. 40 miles, or 63.3km, would hit mach 9.4, or 29% of escape velocity. This is all assuming the vehicle has no propulsion of its own. If we give the vehicle it's own propulsion, we might not even need to get it going that fast. Just fast enough so that it can get out of the atmosphere under it's own power.

I just don't think a trebuchet is the right idea for a job like this. First off, getting the energy direction correct would be quite difficult. Second, where the heck are you going to find a counterweight big enough to hurl a 50-ton (if not more) vehicle into space?? The record I've seen for trebuchets is a 50,000 lb. counterweight that launched an old Buick over a quarter of a mile. Unless you totally redesigned the trebuchet and gave it a much longer counterweight arm, you wouldn't be able to get what you need to launch this massive thing into space.


Not completely relevant but useful information.

Trebuchets don't "scale up" like I knew it wouldn’t, they should damn it.
Parameters (weight of the counterweight, arm lengths, sling lengths, mass of projectile, I think I now have a project of math all night for the rest of my work week... The math is not trivial for this system several coupled differential equations. I am so out of practice. All well, I have a year of trial and error right; let’s just hope I don’t kill my self messing about with this childish dream of smashing box trucks.

About the only thing I think I got right on my initial calculations was that the height of the “tower” would need to be around 50 feet. But after crunching the numbers I think I was a little too ambitious. We would need a counter weight closer to 27800lb to launch 3000 lb 300 meters. I don’t think I need to point out that, this is a lot of weight flying around on a structure built by armatures… Truth be told I think Flinging a projectile with a mass off 1000lb might be beyond my capabilities. Fear not I am not giving in, just seriously re-thinking my strategy. As I said, I am going to start this summer on smaller more manageable scale and see where I end up.

Ok, I think I messed something up... That doesn't seems like an awful lot of counter balance, Time to re-work.

I think I am actually going to build a series of them working my way up to the Big Bertha. Big Bertha can be the queen of next summer.

After some brief touching up, ( http://www.comfsm.fm/~dleeling/physic... ) I think the biggest problem will be scaling up the Sling to withstand the tension of 3000 lb. None the less I think about 22ooo lb. should give us enough force for a successful launch. Again, what I am worried about is the whip or arm snapping. I don't think a back firing trebuchet would be a good thing.

Haven't you ever just wanted to have something cool, Lori? Well I personally think a trebuchet IS pretty fucking kewl. And so will my Neighbor when a 3000 lb. Toyota is sitting in his bedroom.

I just want to know what the hell is going on. I have been up all night all week, and everyone shuts up at 9, now it is 1113 and people are still talking... ZOMBIES!


**runs away**

I didn't know you had a dog. What kind.

August would be a bit late in the year (for Alaska)... '09 would be good; plenty of time to make a few prototypes, and Charissa can fly up or drive up and take the ferry.

I will be talking to the misses in a little bit, and get confirmation for the whole project. I think I will push for a week just in case, you never know, once we have successfully launched one car we may not be able to stop.