"Fav'rit 2 B" - Build and Flight Log

Cl(VII) said:

The big thing I learned between start of this project and today is to never overlook how stability changes over the course of the flight, and don't assume it starts where the little dot in OR is and gets better as fuel burns off, tha little dot is I think related to the max velocity, not the just cleared the rod velocity. This is a big deal for small fins, and I fear I came very close to doing some skywriting.

Click to expand...

How far off was your stability at rod clearance? I noticed on a project I have been working on that OR (in the stability vs. time graph) shows stability at .87 calipers at launch rod clearance, and achieving 1.0 calipers less than 0.1 sec into flight. Is that what you are referring to, or something more significant? What is the minimum acceptable stability at launch rod clearance? 1.0 cal?

Sorry for my own Noob questions and jacking your thread, but I guess that is why we are on the forum.

Mr Rocket said:

How far off was your stability at rod clearance? I noticed on a project I have been working on that OR (in the stability vs. time graph) shows stability at .87 calipers at launch rod clearance, and achieving 1.0 calipers less than 0.1 sec into flight. Is that what you are referring to, or something more significant? What is the minimum acceptable stability at launch rod clearance? 1.0 cal?

Sorry for my own Noob questions and jacking your thread, but I guess that is why we are on the forum.

Click to expand...

In the extreme case for the motors I had on hand for the flight with the rocket pre-noseweight, i.e. how I originally built it, H112J: the static picture that OR shows as you build the rocket was 1.5 cal stable. The flight as it cleared the rod -0.30 cal (stability versus time graph you talked about), Yikes! It didn't theoretically achieve 1 cal until about 1 sec into the flight, but I doubt it ever would have got up the airspeed to achieve that.

Now there appears to be a little difference of opinion in what is acceptable, and how much time after rod clearance you need to attain the magic 1 cal, but there is no way negative cal is going to be good. I solicited some advice on this exact thing in the below thread before deciding to add nose weight.

https://www.rocketryforum.com/showthread.php?64355-Opinion-on-Stability

Also, no problem on the question, again glad this thread has been useful.

Yikes is right!!!

I never realized there could be that drastic of a difference in stabilty as the rocket leaves the pad. I knew there could be some, but I never would have expected 1.8 cal. The stability vs time is a function I recently discovered while working on a spin stabilized low power rocket. I definitely will be looking at it more now on conventional rockets.

Glad that your diligence paid off with the successful flight!

I think I'm going to use this thread like a flight log, so Flight #2.

Gunter, TX
4-26-2014
AT I-245G
Alt: 2148 ft

This was the first flight in full DD mode, and it went pretty well. It looks like from the altimeter data that the backup main charge is the one that blew the NC. I did ground test and 0.8 g was fine, but then I did the emergency nose weight addition and never retested. The backup was 1.0 g, and strangely did not shear the pins, but stripped them from the NC. I think I will change to 1.0 and 1.2 for future flights. Other than that and the long walk it was good.

Pics curtousy of Nick V (TRF's "Talon"), and posted with permission.

qquake2k said:

Looks like a nice flight! What motor was that?

Click to expand...

Aerotech I-245G. The little one's favorite color is green, so I couldn't resist. I heard about the green fire for two days.

I lost track of this thread some time back...

I love what you did with the thing...

Congrats on your Level 1!!!

Cl(VII) said:

I think I'm going to use this thread like a flight log, so Flight #2.

Gunter, TX
4-26-2014
AT I-245G
Alt: 2148 ft

Click to expand...

This was a great flight. The photo doesn't capture the green of the flame. And the finish looks even better in person. "Intergalactic Space Pimp" is right. The rocket needs a ring of little pompoms around the nose cone. And some fuzzy dice.

AlfaBrewer said:

This was a great flight. The photo doesn't capture the green of the flame. And the finish looks even better in person. "Intergalactic Space Pimp" is right. The rocket needs a ring of little pompoms around the nose cone. And some fuzzy dice.

Click to expand...

Fuzzy dice may make an excellent anti-zipper device...hum.

Thanks for amending post #1 to include the OpenRocket files, thats a great looking rocket, sort of reminds me of what would happen if you crossed a Thrustline Arapahoe-E with a Madcow Prion.

rharshberger said:

Thanks for amending post #1 to include the OpenRocket files, thats a great looking rocket, sort of reminds me of what would happen if you crossed a Thrustline Arapahoe-E with a Madcow Prion.

Click to expand...

Funny you should mention the Arapahoe.

Cl(VII) said:

Funny you should mention the Arapahoe.

Click to expand...

I know I followed that build pretty closely myself, and am planning to do a L2 capable one someday, which nose cones did you use for the NC and which did you convert to at TailCone on your Arapahoe-J.

Edit: Nevermind I found the info in post #7 when you listed the parts.