Sunday 26

Any 1 out to play later perfect at the moment clear blue sky

Hope to be there before two Gary

I'm hoping to have a couple of hours out playing later this afternoon, got a present for you Rich

Andy

no present for me Andy

I'm sure he'll give you one if you like

I can't make it up today as I've slipped a disc.
2 nice flying days missed now,GRRRR.
I maybe up in the next couple of days.
Have fun guys.

Danny.

You didn't miss much Danny, just some really nice sunny weather, not much wind, some cracking planes, and a buffoon being rather successful in shortening a foot long Rocket into a space about an inch long

Andy

The guy who was at the field with a camera early on has just emailed me a couple of shots of my Ultimate, here's one, not bad as I don't think he had an exceptionally long lens
By the time I got back to the pits parked the model he was gone I didn't get chance for a chat

Yep nice guy, lives in Abergele.

Will Bertoni received his "B" certificate from Richie today having past his test about three or four weeks ago. Well done Will

Good effort Will, well done.

well done Will

Good afternoon flying, right up to the point i spanked my Yuk!, Ahh well

Bri's Ulti looks like its going well now with plenty of power on tap, Nice to see Mats out to play and the rocket man.

M

Did a quick calculation whilst "Holding the Baby" last night at about 3am, and that little rocket that hit the ground a bit hard was doing approximately 280mph when it hit the ground, based on the trajectory and engine size....

Andy

PS, well done Will

Andy Sayle wrote: was doing approximately 280mph when it hit the ground, b

Andy

At last!, Usfull mathmatics!

post the equation so I can run through it,

was it something like this



or this

It's not amazingly complex. I know the motor burnt for 2 seconds, and I know the impulse of the motor (16N/s) I know the weight of the rocket, and I know the motor hit the ground just as the motor burnt out. So I split the flight into two sections. The going up bit, and the going down bit. Now just use the equations of motion (see here: http://en.wikipedia.org/wiki/Equations_of_motion) and plug in the numbers to see how high it went, and how fast it was hitting the ground from there.

Of course there are assumptions, such as that the model went stright up and stright down, when in fact it went sideways a fair bit, and that the thrust from the motor was constant over it's entire burn. Those tend to cancel each other out though, so the calc is good enough for me

Andy

I got it to 267.3mph

You forgot to take into account the air temperature and pressure at the time......

Andy

Ahh bit i did calculate the curveture of the earth

The curvature of the earth would have been completely negated by the length of the grass at the impact site, and I bet you forgot to take into account the 0.2m starting height on the launch pad

Andy

What about wind direction and velocity?

Oh, and humidity and dewpoint!