Diamond Cutter build thread

Final weight without parachute = 4.5 oz, or about 0.15 oz higher than last measurement. So the nose cone retainer + Future = 0.15 oz.

Measured CG comes in about .6 calibers further aft of OR's prediction. That's enough difference that it makes margin a bit tight with a D engine; I'm very glad I had a bit of extra margin built into the design (and I'll be sure to include extra margin in my future designs as well.) An altimeter in the payload section will restore order; if flying without an altimeter I might even put in a very small bit of nose weight.

FINALLY launched it today.

Here it is on the launch pad:


Here I am with it:


In case you're wondering, I did not intentionally wear clothing to match the paint color.

Here it is climbing the rod:


Unfortunately that's the last good look, because it cocked heavily off the rod and sort of waggled its way up. All in all a rather lousy flight, but I did get it back in perfect condition and will try again in the future. I don't know if it hung on the rod or what; on a D12 it certainly should have zoomed a heck of a lot quicker than it did.

On a side note: this was my first Top Flite thin-mil parachute. I *love* it, and will probably use it for all my future LPR builds. It folds *really* small.

:clap::clap: Woohoo! She flies!

Must feel great to let it stretch its legs a bit. Might be a bit of sticky residue on the rod or even a little ding in the rod tip.

So glad to see it recovered safely too.

The pictures don't do her justice
She's awesome !! (did I hear UP-SCALE?)

Too bad I missed the flight

Good to see you again Neil

I said this in The Watering Hole post; it looks to need more impulse. Like an E20 single use or maybe an E18 reload. It cocks off and waggles due to not enough speed off the rod for the fins to stabilize the flight at the start.

If you're confident in your CG/CP relationship then heck yeah, let's see it go on an E20! Congrats on getting this in the air; the picture of it next to you gives a much better impression of its size; bigger than I thought it was. Very cool design!

dave carver said:

I said this in The Watering Hole post; it looks to need more impulse. Like an E20 single use or maybe an E18 reload. It cocks off and waggles due to not enough speed off the rod for the fins to stabilize the flight at the start.

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I agree that's how it looked (with my eyes as well as from my description), but I'm having a hard time making sense of it. It's about 5 oz without engine, which is very close to the Solar Warrior, and the Solar Warrior scoots off the pad in a big old hurry on a D12. A D12 should not have any trouble with a 5 oz rocket on a 6 ft rod.

Thinking back at it, I'm becoming more convinced that it must have somehow stuck on the rod, which caused it to come off more slowly than expected. I actually spent a bit of time there making sure the lug felt smooth on the rod, but maybe I still screwed it up.

Thanks to all for the kind words. It is a nice looking rocket, although even before it launched it looked like it had been through a war. Gotta learn to handle things a little more gently during the build and finishing process I guess.

BTW, if swatkat were here he'd be recommending an F44.

sticky rods are always a possibility, as is a bit of paint inside the lug (or even a slightly undersized lug).
Rex

dave carver said:

I said this in The Watering Hole post; it looks to need more impulse. Like an E20 single use or maybe an E18 reload. It cocks off and waggles due to not enough speed off the rod for the fins to stabilize the flight at the start.

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+1.

Rex R said:

sticky rods are always a possibility, as is a bit of paint inside the lug (or even a slightly undersized lug).
Rex

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Yeah, I'll make sure the inside of the lug is really clean before the next launch.

The Diamond Cutter went up on a D12-5 yesterday at BARC. In contrast to its first flight, this one went perfectly and it went arrow-straight and quite high. Deployment was perfect, no problem with recovery, everything is in perfect condition.

I had planned to fly it a second time, but the wind started picking up later in the day and after a *very* long walk to recover Biohazard (after thinking it was lost) I decided to exercise some discretion and retire DC for the day. But she will fly again next opportunity, once I get some more engines.

So I'm just going to write off that first flight as a weird fluke.

Pics to come soon I hope. Here's one: