Recent content by kjr

What would a typical lift to drag ratio for an RC model aircraft be? I'm currently getting 8-10, which seems a bit low.

Sad to see him go. I was just reading about his work a few days back :/

Hi everybody, From my previous experience this is the place to find very smart people with tons of experience, so i turn to you guys (and girls) for some help. I've got a new coursework project and i'm trying to make sense of it all. I'm dealing with flight management for the first time time...

Just thought i would report on the competition. I didn't manage to get the consistent results from testing as i planned, so just decided to use what i have and it wasn't too bad. Our team was only about 5cm off to the side from the targets, with the distance pretty much perfect. I think the...

Redesign isn't an option at this point :/ It's a shame we were given these as-is. I would have loved to design my own catapult. Some issues i'm having with this one drives me and my group crazy (especially the release; or more specifically the lack of one)... Since i'm massively running out of...

That's what i'm thinking now. I determined the spring constant by running it through the tensile testing machine, the graph it produced is quite standard and fits Hooke's law. However, only small extension was used during the test, so that's not going to prove that that it behaves linearly...

I'm not sure about that. There isn't a great deal of it to be fair. I don't think it would cause such a big difference. The arm is pinned through two pylons on either side of it with an M6 bolt (the catapult is really small, total arm length - 330mm, height - 200mm, powered by two parallel...

Thank you, Tommy. Well, i've incorporated a hard stop for the catapult. It's a bit crude (a pin inbetween the supports, constant release angle 40deg). I've built the mathematical model using the energies as i've stated before. I've got a strange issue though, it's dead accurate when firing from...

Thanks for all your input, i didn't even think about the slowing down of the arm. If the cradle wall is tall enough, the lever should maintain the trajectory, whilst it's not providing any more 'push' past the horizontal, as Tommy said. So if i find out the difference in energy when the...

Hi everybody, I have a little catapult project, the physical thing is given to us and we need to build a mathematical model to predict the range of the projectile. I'm attaching a sketch of the problem. If i know the velocity and the angle that the projectile leaves the catapult, it's quite...