Post-Build Modifications to Custom Rocket Company “Aztec”

[brockrwood]

At the last launch of my Custom Rocket Company “Aztec”, two-stage rocket, the rocket seemed to make a hard left turn off of the pad. (Is that a hook or a slice?)

It is pretty short (15 inches) for a two stage rocket, even with the swept back fins.

I am putting a bit of clay in the nose to move the center of gravity forward.

Also, the streamer recovery lets the model come down pretty fast. The sustainer with a spent engine in it weighs in at 50 grams. I put a small parachute in instead.

Pics:






The stock, wide, 1/4 inch elastic shock cord took up a lot of room in the sustainer body tube, which is only 9 inches long. It is a tight fit to get the wadding and shock cord and recovery wadding and the nose cone all into the body tube. (The shoulder of nose cone is 1 1/8 inch long.).

Dear rocket kit manufacturers: Please add a few inches of length to your short rockets so we can get the laundry to go in without having to cram everything in tightly.

Anyway, I cut off most of the elastic shock cord and tied on longish piece of kevlar cord as the shock cord. Takes up much less room in the body tube:



Moral of the story: A kit rocket is still YOUR rocket. You can modify it any way you wish if you think you can improve on the designer’s ideas. You can even modify it after you have built it. Hack away!

PS: Yes, that is dental floss for the parachute shroud lines.

 

[bjphoenix]

I don't know what causes the hard left turn. It's possible that if it has a lot of stability it could be reacting to wind. Or maybe it doesn't have enough velocity at the top of the rod. Do you have a sim of it that shows the amount of stability margin?
Last year I launched an Estes HiFlier XL on a D12. It flew straight up. Later in the day I launched it again and it did a hard right turn a little bit off the rod. The conditions were the same for both launches so I don't know what happened. The HiFlier XL has a big margin of stability but there was very little wind that day.

 

[Sooner Boomer]

One thing that will help in rockets where they don't seem long enough to pack every thing in, is to use a paper chute protector instead on dog barf or wadding:



I had a real problem with my Mega Rebel. I couldn't fit enough wadding/barf in to keep from getting the chute scorched. I used one of these at Airfest, and it worked great! (sized appropriatly for body tube). I coated the area "INTO MISSILE BODY" in the picture with two layers of yellow glue to give extra protection (this is on the outside of the piece, closest to the engine)..

 

[brockrwood]

One thing that will help in rockets where they don't seem long enough to pack every thing in, is to use a paper chute protector instead on dog barf or wadding:

View attachment 538330

I had a real problem with my Mega Rebel. I couldn't fit enough wadding/barf in to keep from getting the chute scorched. I used one of these at Airfest, and it worked great! (sized appropriatly for body tube). I coated the area "INTO MISSILE BODY" in the picture with two layers of yellow glue to give extra protection (this is on the outside of the piece, closest to the engine)..

Do I use flame resistant crepe paper, parchment paper, or some other type of flame resistant paper?

 

[Sooner Boomer]

Do I use flame resistant crepe paper, parchment paper, or some other type of flame resistant paper?

I used plain typing paper. For larger diameters, I may go to cardstock. The two layers of yellow glue seem to flameproof it pretty well. You could alternatively glue a cardboard disc to the same area (disc small enough to easily fit down body tube).

 

[cls]

hey the paper chute protector is great! I'm going to try that soon.

 

[bjphoenix]

Do I use flame resistant crepe paper, parchment paper, or some other type of flame resistant paper?

I've been using plain cheap crepe paper for my reusable wadding. I made a pompom similar to what some people made out of teflon plumber tape and it worked great for BT60 size rockets. At the last launch I couldn't find it in my box but I also had a crepe paper streamer in there with a loop on the end so I just stuffed it in the tube before the parachute and it worked perfectly.
I've wanted to try those chute protectors. I was thinking I would mix up some of the flameproofing solution and make some of these out of paper towels but for most of my launches the crepe paper works perfectly. But I have a Big Daddy and an Estes V2 (made from a Silver Comet) and neither of these has much body tube length to fit in sufficient wadding or dog barf or whatever so for those the disposable chute protectors would work well. But come to think of it if I could get bigger sheets of crepe paper I would use that.