At 01:39 AM 10/14/99 -0500, you wrote:
>Not caused by the extra ignition.. E engines have a SERIOUS problem with
>cracked grains, resulting in explosion.

Ah, I see. We had speculated that the gunpowder he added had actually not
gone in the engine, but had accumulated elsewhere in the rocket. I guess
your explanation is more likely.

>600's a BIT optimistic. 300 I'd believe.

Again, you are probably right. My guess was based on #1) I thought that
normal,light D-engined rockets reach nearly 340 kts vertically. #2) This
one had an E in a D body #3) It lost its fins -> much less drag #4) It went
horizontal -> no gravity to beat (not a big factor, I realize)

SO,I knew it was unlikely that it went supersonic,but I felt that it would
have reached lower transonic region.

>
>My toys start with H engines, and I'm certed through J. I've broken mach,
>but it took a few more logs on the fire than an E engine will give.

Where do you get the money? Doesn't that get expensive REAL fast?

>
>The mos hideous question we get is for a "schematic for a radio controlled
>launcher" or a "computer controlled launcher"...  It always sounds like a
>cool idea, until you understand the penalties for one wrong ignition.
>

Yeah, but it does seem to me that there would be ways to make it every bit
as safe (i.e., actually preventing power from reaching the unit until you
turn a key,etc.)

>I was at the meet here in muncie when AFAIK the first injury directly
>related to model rocketry occurred. A fellow was prepping his bird, and had
>his head over/inside the body, when the computer-controlled ejection malfed,
>blowing at least a gram of FFFF powder in his face.  We had an optometrist
>on him in seconds (damn good luck!) and an ambulance rolling in a few more
>seconds. His sunglasses saved his eyes.

I don't know what FFFF powder is,but this definately doesn't sound good!
I have never gotten into serious rockets,but I'd like to. (non-sequitor to
previous comment!)

>
>This computer controlled recovery system is commonly used, but apparently
>his safety interlocks weren't functional, and it blew.  They sense by
>barometric sensor, and it may be that a drop of sweat or conductive debris
>hit the controller board.
>

Sounds like we're talking some serious altitude! How high have you gone?

I think the US is one of the few countries that allows people to launch J
engined rockets to Mach 1 and 30,000 feet!!! (of course, you need clearance
first for such an altitude. Shound need clearance for anything over 18,000
(lower end of mandatory IFR airspace) right?

Sean

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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