Monday, April 14, 2014

New water rocket launcher

I just received a launcher and two screw-on fins sets from StratoFins. I had considered building a Clark cable tie launcher for some time but somehow never got around to it. So, when I saw one for sale, I couldn't resist. Another good toy for the grand-rocketeers!

I bought a mostly pre-assembled launcher because I'm lazy and I was hoping to use it this week. As it turns out, it arrived days early (ordered from Amazon) and the weather on the target launch day may not be conducive for water related sports. I will freeze here tomorrow tonight and we might even see some flakes. :eek:

The only assembly required was to screw the launch tube into the base. The PVC threads came covered with Teflon plumbing tape to eliminate air leaks. I test fit a fin unit and it seems to operate well. If you want to see how this type of launcher operates, I'll refer you to StratoFins' and/or AirCommand.

The four piece fin units are easy to assemble and appear to be sturdy. They screw onto standard soda bottles (2L and below, at least) and have a lip to mate with the launcher. The base of the hub also is threaded so it will mate with the quick-connect fittings that are used on the Quest water rocket launcher.

StratoFins also sells a parachute and describes an interesting way to connect it to a water rocket. Each pair of riser cords are looped over one of the fins. The cords are then brought together at the top of the rocket and are cinched with a cable tie. The 'chute is folded and set on top. A nose cone is made by cutting the top off another bottle. At apogee, the nose merely falls off and frees the 'chute. This almost sounds too easy and I'm wondering if the nose will occasionally (often?) fall off while the rocket is boosting. However, StratoFins offers a few videos of this set up working. I suppose I'll eventually try to find a mechanical timer to make a more positive release mechanism.

Sunday, April 13, 2014

Saturday, April 12, 2014

Extending a motor mount

First some background. A couple of flying seasons ago, I lost two 24/40 RMS casings and, so far, haven't replaced them. That grounded a few of my rockets that required more thrust than a D12 or E12. I have a 29/60 case and, while the main body is the same length as an E12, the charge well extends further. And, unfortunately, several of my rockets use spring motor retainers and/or engine blocks. The 29/60 doesn't fit in these. (I never used blocks on HPR and ditched them a long time ago on my 29mm MPR builds. However, I continued to use them on 18mm/24mm kits and some scratchers.)

I decided to figure out a way to adapt one of my earliest post-BAR 24mm birds, the BNC-R1, for the 29/60. I first Dremeled-off the spring retainer. I found that a BT-70/24mm plywood centering ring was about the same diameter as the body tube. Thus, it would work well as both a thrust plate and a mounting point for an Estes PVC retainer. I mounted that retainer to a short piece of BT-50 and the ring, just as if it were the end of any other rocket. I then sectioned another piece of BT-50 and slid it over that tube. This sectioned piece was measured to it would overlap the existing motor mount. I also found that the packing tube from 38mm CTI reloads was close to the ID of the BNC-R1's body. I added a short section to provide more 'bite' between the new bulkhead/centering ring and the old one.  All these parts were epoxied together and, tadah, the BNC-R1 will accept the 29/60 and anything shorter.

Luckily, the old rocket was stable enough to accommodate the extra parts, larger  motor, etc. 

Friday, April 11, 2014

Launch Report 2014-3

Location: Higgs Farm, Price, MD (Red Glare XVI)
Weather: 75 degrees max, partly cloudy and dry, wind 5-10
Total flights: Today - 6; YTD - 15
Total motors: Today - 10; YTD - 19
Motors by class YTD: MMX-1, A-2, C-3, E-5, F-5, G-2, H-1

This was the first day of Red Glare. The weather forecast had oscillated between good and bad and good won out. The launch rate started ligh but got heavy between about 12PM and 3PM.

My Flights:
  1. Landshark on a G64-4 - Nice flight with a little 'bonus delay'.
  2. Thoy Snipe on 3 x E9-4 - Great boost. The 'chute came out on cue but about 2/3 of the way down the body dropped off. This is a vintage kit that includes an elastic shock cord. However, it wasn't the elastic that failed. It was the Kevlar leader that connects the stainless steel wire mount to the elastic. The landing was 'one point' with one fin stuck in the dirt. No damage.
  3. Public Enemy Ultra Fat Boy on a G115-6 - Nice boost with late ejection. Long walk.
  4. Estes Mega Mosquito on an F15-4 - Nice flight with ejection a fraction of a second early.
  5. Talos, Block 2 on an E16-6 and two C11-7 - Nice boost until the booster motors' ejection charges went off. My plugging wasn't sufficient. One booster mount disappeared and the other on blew apart.
  6. Whirlygig38 on an H100 - This spun like crazy and rose fast (see video in the photo set linked below). Near max-Q, one fin came off and took the tube with it. This caused a large pucker factor in the crowd but the fin fluttered down harmlessly just a few feet from me. An analogy to this flight was the old saying, "the operation was a success but the patient died." A G-80 would have been a better choice. Oh well.
All my photos can be found [here].

Thursday, April 10, 2014

Lockheed NF-104 Starfighter

Click through to the original image to read a short history of this rocket-boosted variant of the F-104 Starfighter.

Tuesday, April 08, 2014

Retro, rocket, girls

I found and subsequently lost a new retro photograph blog. Oops. Anyway, here is what I found.

A retro pyrogen wrapper.

Proof that 4 out of 5 spectators don't pay attention when the RSO yells 'heads-up!'???

The History of Space Guns

I found a nice article via TRF: Space Guns - A history of the least subtle way of getting into orbit. The author, Duncan Geere, starts with Newton and ends with the current status. He focusses on conventional canons and compressed gas guns and, unfortunately, there is only one brief comment on rail guns. Here is a cool photo of the HARP 16" gun firing.

Sunday, April 06, 2014

V-104: The Good, the Bad, and the Ugly

Well, I finished painting the fins and attached them melt glue. I had a hard time bonding to this plastic when the F-104 was an F-104 so I thought I'd try something new. I figure the worst case is a fin cleanly pops off on recovery. I ran some design sims and find I likely need a quarter of an ounce of nose weight. The resulting rocket should fly well on an A8-3, B6-4 or C6-5. Yay.

The Good: The resulting rocket is an altogether satisfying V-2-like object. And, a good way to honor the F-104's memory. Check out the shot with it between a Semroc BT-55 V-2 and my scratch-from-plans BT-50 Mini V-2.

The Bad: There is not much recovery room given the found parts that I used and the base of the fins are not perpendicular to the rocket's longitudinal axis. I failed to consider the base when sanding the Semroc V-2 fins to fit.

The Ugly: I had 3 extra, unused cans of Rustoleum flat black when I started. The first wouldn't spray even though is was brand new. The 2nd can worked fine for the first side of the fins but began to clog and splatter on the 2nd side. I have never had this happen on a can that is less than a season old. Some cleaning and 10x the shaking and I kinda, sorta, mostly got 2 coats of paint on. The result looks OK from 10'. But hey, this me, what else would you expect? And, third spare can will be returned.

Despite the bad and ugly, the Good won out big time :)