Launch 2-12-05

Here I will get a chance to try my new delay grains for real.  
They have performed well in static tests, with only a couple of significant failures in quite a few tries.  
But a couple is a lot.  Note that the launch rod is tipped away from the spectator area, just in case.

In addition, these cases are loaded with the new case liner/propellant grain packages that are so easy to load.  

Here is the "Little A" which is my red Ariel minus its payload bay, set up on pad 10, ready to launch.  This launch is using motor ejection in the 38-480 casing, with a 2-inch long dual diameter delay grain.  This delay took up a bit of room in the propellant area, so the impulse was more like that of a fully loaded 38-360 casing.

Glad I took this photo, as it shows the dry patch of grass behind my rocket.  The significance of that fact will soon become clear.

(Click the photo for a larger picture.)

Click the picture for a movie of this flight.
(Beware, 5 meg file, 25 seconds of flight to apogee and parachute ejection.

Do you know the Alt/Enter trick?  
Hold the Alt key and press Enter to make the video full-screen.

Esc makes it small again.

As the rocket descended toward the sod, someone yelled "Fire! ....  Jimmy!  You started a fire!"  

Someone else said:  "How many rocket scientists does it take..."

So I yelled back something unbearably clever, like:  "Good!  It will give you a chance to play with the fire extinguisher."

Someone did.  Fire was out in a minute or so, and I went off for my rocket.

It landed about 1000 feet away, a nice walk on this very pleasant day.

Loaded and ready to go again.  This time using an uninhibited grain in the 38-480 casing.  It is still not quite full length because the delay grain is 1.5 inches long.  Thus it extends into the casing about 5/8ths inch, taking up a little propellant space.  This will be a short burn, but should achieve about the same altitude as the last launch.

Note the burned grass on lower right. That was my fault.  And yes, it was downwind.  Note the way my hair is blowing.

Thanks to Stephen Kiss for this photo!

Click this photo for a movie of the flight. (4.7 meg file for a 20 second movie.)

This motor used an uninhibited grain, so the burn time is very short
.  I have fired so many of these in static tests, I just had to see how they worked in flight.  Pretty well in terms of heaving the airframe upward, but I miss the Doppler effect of a long burn.

1.5 inch delay grain was perfect, ejecting right at apogee.  The airframe didn't even get to turn around.
 Hope I can do that again!

After the launch equipment had been stowed and most folks had left, I crept back to the launch site to see "the spot."   Good news is that it was an isolated patch of dry grass, and the would not have gone anywhere if it had been left to burn out.  Many farmers around here burn their fields this time of year to help the grass grow back.  

Bad news is that I owe the club a fire-extinguisher recharge!  And I must endeavor to be more cautious with the launch site from here on, especially when firing Ti-enhanced propellant.      

Another fine launch, thanks to the NEFAR folks.  
The loads performed well, the delay grains worked, and the airframe is still intact.
Accidental grass ignition did not result in injury, property damage, or severe humiliation.

Maybe I'll try it again!

Jimmy Yawn
Recrystallized Rocketry