I made a trebuchet on a similar concept, except I had the sling increase in in length as the counterweight fell. I though increasing the weight would override viscous losses;however, this thing did not work according to plan.
I'd forgotten that I advertised efficiency for this treb. I regularly do it now for my more recent MURLIN trebuchet endeavors (see Dynamically Tuned MURLIN), but don't always advertise it.
My simulations show that you are right-on and that the extra rotations quickly gobble up energy with friction and aerodynamic drag. This is the main reason I haven't pursued MRTs any further.
Congratulations. This is the first trebuchet vid I've come across on Youtube which supplies enough info to let us calculate the efficiency.
I suppose 23% is not bad in the circumstances. I had a similar idea once once, but abandoned it when I realized that a system that needs multiple rotations is one where a large slice of energy is going to be eaten up in friction, especially air friction. I think the key to efficiency is to get the missile up to top speed and away as soon as possible.
It's probably not clear from the video, but there is a sling from the projectile up to the other end of the throwing arm. If you look carefully, you can see it. The sling deploys and actually spins the throwing arm backwards before release.
I made a trebuchet on a similar concept, except I had the sling increase in in length as the counterweight fell. I though increasing the weight would override viscous losses;however, this thing did not work according to plan.
Check out this trebuchet though -
youtube "klondike time trebuchet"
vanityemm 3 weeks ago
Hmmm...Are you asking how I can keep the projectile in place for 4 rotations and then release it?
ldvance01 4 months ago
1.21, how can you have 4.5 full rotations?
doctorgear63 4 months ago
I'd forgotten that I advertised efficiency for this treb. I regularly do it now for my more recent MURLIN trebuchet endeavors (see Dynamically Tuned MURLIN), but don't always advertise it.
My simulations show that you are right-on and that the extra rotations quickly gobble up energy with friction and aerodynamic drag. This is the main reason I haven't pursued MRTs any further.
ldvance01 7 months ago
Congratulations. This is the first trebuchet vid I've come across on Youtube which supplies enough info to let us calculate the efficiency.
I suppose 23% is not bad in the circumstances. I had a similar idea once once, but abandoned it when I realized that a system that needs multiple rotations is one where a large slice of energy is going to be eaten up in friction, especially air friction. I think the key to efficiency is to get the missile up to top speed and away as soon as possible.
ketmaniac 7 months ago
It's probably not clear from the video, but there is a sling from the projectile up to the other end of the throwing arm. If you look carefully, you can see it. The sling deploys and actually spins the throwing arm backwards before release.
ldvance01 10 months ago
i want to build a similar one, but with a sling. do you think that would increase the efficiency?
BigMackes 10 months ago