SpudFiles

I'm gonna build an All-terrain RC vehicle with a combustion on it. (no, i'm not gonna release ANY details on it anytime soon ) I was wondering what angle I should I place the barrel to achieve maximum distance with a variety of ammo?

45% is the theoretical angle in a vacuum but in reality for rifled projectiles it's closer to 35% and for drag stabilised projectiles usually 55% - I would go for the latter as it's more applicable to spudguns.

Even in vacuum, 45° isn't the optimal launch angle to maximize distance if your launcher is elevated above the horizontal. Probably won't make that much of a difference on top of an RC car, but there's that.

Use GGDT and a measured drag coefficient to calculate your optimal launch angle.

@JSR: Where did you find those figures? The optimal launch angle is always below 45 degrees, regardless of how the thing was stabilised.

The best angle for most projectiles is 30 to 35 degrees I find.

@markf11hq: Or he could tell me some basic data, and I could calculate it much better than GGDT will.

Ragnarok is right, the launch angle that maximizes range is only 45 degrees in a vacuum. In air it is always less than 45 and usually in the 30~35 degree range.

Since flamerz14 asked about the launch angle for "a variety of ammo" it probably isn't necisary to calculate the angle any more accurately than that.

The 55 degrees rule applies to guns powerful enough to reach the thinner air in the upper atmosphere where drag is reduced, apologies for the misquoted data.

I gather that there is however a difference between rifled and non-rifled projectiles, as they retain a different attitude in flight.

I haven't decided on the specs of the gun, but it will be a combustion, small sized(not a mini). ammo will be 25mm beads or marbles and ping pong balls filled with paint

why don't you just use servo's or pnuematics or something so that you can remotely move the barrel up and down?

it just makes sense