why?
 

Why does the suction cup projectile-fired from a toy spring pistol--NOT turn around in flight and hit the target, travelling backward?
If you look at it - it looks like an arrow flying backward.

RE: why?
 

distribution of mass

RE: why?
 

Most of the mass of the dart is in that rubber cup. As long as the center of mass is ahead of the center of drag, it will be stable.
Air rifle pellets will also stay nose forward, even when shot from a un-rifled barrel, for the same reason.

RE: why?
 

OK- where is the cg?

RE: why?
 

I tried to research these things on the web - got nowhere except to find out there are some really weird people out there who are into shooting things at each other.
The business of having the mass forward - was apparant from the onset but the best relative aspect ratio and any serious analytical info was not found

RE: why?
 

With the mass forward the plastic stick itself acts like tail fins. Like if you take a stick of balsa and screwed on a metal nut to one end. That moves the CG toward the nut end and the stick itself has enough of an aerodymaic effect with the majority of the area behind the new CG to stabilize the resulting "arrow".

The cup itself obviously has a lot of drag and side area of it's own but apparently it is not enough to make up for the effect of the dart's tail that is behind the CG and has a longer tail moment arm to lever with and ensure the cup stays dimple frontwards.

And for the sake of simplicity in this forum we'll forget about the effects of excess spit on the cup and the assymetrical effects that produces...... :D

RE: why?
 

Well, there goes MY next question... :D;)

Blue skies,

DL

RE: why?
 

OK- I thot I would get formulas and wind tunnel data --
I guess Uncle Sam never took these things seriously.
The crazy thing is -- the reason most of out little models fly well-is just as simple but the data to explain what is happening is endless.
Go figger--------

RE: why?
 

BUT.....if you're standing on a conveyor belt moving exactly as fast as you can run, will the dart ever leave the gun, lol?

RE: why?
 

Hmmmm --- only if it has frictionless bearings.

RE: why?
 

I was stunned by the lack of logic I saw on that one!
Here's a toughie
Why don't chickens P ?

RE: why?
 

It's distributed in other mass.

RE: why?
 

Thanks Dick -----------Just dropped my beer when I fell out of my chair laughing :D

RE: why?
 

well that's 1 for 2 ----

RE: why?
 

Toy firework rockets have the motor at the front.. a big lump.. and a long stick at the back for stability.
The design dates back to William Congreve ... abt 1805
http://en.wikipedia.org/wiki/William...%28inventor%29
The "rocket's red glare" in the National Anthem refer to Congreve rockets fired by the Brits at Fort Sumter.

RE: why?
 

I haven't looked it up, just going from memory: weren't the Chinese first on that one? Say, about 1000 year b4, give or take a century or 2. Truth be known, I wasn't there, but I do remember reading that somewhere.

Something I haven't tried but might be worth a bottle rocket or 2, why not move the rocket down on the stick, hey Dick? I have a pretty good idea of what will happen, but heck it would be fun to do

MattK

RE: why?
 

yes -moving the C/G aft screws up Center of Pressure and instability sets in .
Rocket- airplane -car all same-
but not on chickens .
They are unstable till fried.

RE: why?
 

Jeez, does that hold for roosters too??

RE: why?
 

dick, are you trying to say chickens don't fly well cause their CG is messed up by a build up of P? :D

Ed M.

RE: why?
 

Aha -- the infamous P-factor!! Flying chickens can only go in tight circles because of this -- eventually dissappearing up their own fundamental orifices (orifi?). That's why you never (well hardly ever) see a flying chicken.

RE: why?
 

OK guys, I know it's winter and we're all suffering from Parked Airplane Syndrome but PLEASE! Enough with the potty humor. We're supposed to be a family friendly site about airplanes.

RE: why?
 

Po' folks hunt rabbits with sticks with a weight on one end. They learn to throw same accurately if they do not starve first.[:o] Chicken P is white and crystalline. Same is true for snakes and lizards. Amazing what you can learn on this forum, family oriented as it is. ;)

And yes, there are flying, at least gliding, snakes and lizards. :eek:

RE: why?
 

I'm really starting to love this place, we have an honest "normal" question/post and now we are almost talking about launching chickens up on bottle rockets and the main focus is upon how their bowl movements will effect flight, hehe, lmao....... :) Hope none of you guys are working for NASA.

RE: why?
 

I'm sure it was Gandalf who made the first fireworks, though the exact design is no longer known.

RE: why?
 

Dick,

I'm amazed we've had so many inputs----yet----everyone ignored the time honored reply to the question "Why?"

"Because" of course!