Sunday, July 27, 2014

NARAM 56 is LIVE!

Chris Taylor is once again bringing NARAM LIVE! to computers everywhere. Photos, videos and live streaming (I haven't looked at the later).  Here's a teaser that I lifted from the Saturday album.


F15-4 --> F0-0 (a.k.a. you can't light clay)

As I reported yesterday:
I started trying to fly an F15-4 in the Cheetah. After the stock igniter failed to light it, I tried a Q2G2. No go. I decided that maybe there was some clay over the nozzle. I scraped it lightly and tried another Q2G2. Still no joy. More scraping and a home grown igniter. STILL it sat on the pad. I decided to go at the nozzle with a drill bit. After it was way in there and I was still getting clay, I figured out that something was really wrong. I ended up putting it on a static test stand and burning it from the top end. As expected, the nozzle remained plugged. I need to take some measurements, fill out a MESS form, and contact Estes. And, inspect the other motor from the pack! I'll do a separate post as a follow up.
Last night I inspected the motor in question and performed some measurements. Using a caliper, I found the plug, which is clearly visible from the top, is about 3.4 inches down. I measured another spent motor and its nozzle is about 3.9 inches down. This implies the 'bonus plug' is about a half inch deep.

I inspected the other motor from the pack and all my other 29mm E/F motors and found you can see the propellant in the nozzle. That's a good thing. I filled out a MESS form and emailed Estes.



Saturday, July 26, 2014

Launch Report 2014-10

Location: MDRA, Central Sod Farm
Weather: cloudy turning to clear, wind 0 -5, around 90 degrees max
Total flights: Today - 8; YTD - 80
Total motors: Today - 9; YTD - 70
Motors by class YTD: Water-17, MicroHybrid-1, MMX-1, A-3, B-4, C-12, D-6, E-17, F-14, G-9, H-2

The day started poorly with a 30 minute delay on the bridge due to beach traffic. Haven't seen it this bad for over 5 years. Add 15 more approaching the 50/301 split. It was also unexpectedly spitting rain but that quit and the day turned out great. 

I had one weird thing happen. I started trying to fly an F15-4 in the Cheetah. After the stock igniter failed to light it, I tried a Q2G2. No go. I decided that maybe there was some clay over the nozzle. I scraped it lightly and tried another Q2G2. Still no joy. More scraping and a home grown igniter. STILL it sat on the pad. I decided to go at the nozzle with a drill bit. After it was way in there and I was still getting clay, I figured out that something was really wrong. I ended up putting it on a static test stand and burning it from the top end. As expected, the nozzle remained plugged. I need to take some measurements, fill out a MESS form, and contact Estes. And, inspect the other motor from the pack! I'll do a separate post as a follow up.

My Flights
  1. NCR Archer on a G106-5 - Excellent sparky flight with a short walk!
  2. Madcow Jayhawk on a G74-6 - Nice flight, I'm really digging the EconoMax motors!
  3. Big Daddy 29mm on a G74-9 - I drag raced Dave Greger's Old Bay Daddy and Coors Light Daddy, which flew on CTI F motors. They both lit faster than mine but the Daddy really rocked. It also stuck the landing :)
  4. AquaShuttle water rocket (300mL @ 80psi)- Everything worked and it held together. The performance sucked.
  5. FTC-1 water rocket (400mL @ 90psi) - Nice flight with touchdown parallel to the ground.
  6. Mega Mosquito on 3 x E9-6 - I was really nervous about this flight.  All three motors lit and it wobbled a bit on the way up. Perfect recovery. YAY!
  7. Aerotech Cheetah on an G74-9 - Very high with bean patch landing.
  8. Cohete Gigante on an E9-P - Fins were too floppy. It arced over and POP! RIP.
I have a few photos [here] and expect a video of the AquaShuttle as well as stills of the Mega Mosquito and Cohete Grande.

Thursday, July 24, 2014

NASA provides 3-D printable models

Via io9, I see NASA has released 3-D printable models of several satellites, a couple of asteroids, and section of the Moon's surface: 3D Models - 3D printable. They have a disclaimer about some of these requiring tweaking by the user and the longest dimension is about 4".  I immediately hoped for models of rockets and rocket-related parts. On their main 3-D Models page, they have various rockets including Shuttles and Shuttle parts. While they eventually make them printable, at 4 inches these would only be suitable for desktop display. I wonder if CAD-enabled rocketeers could take these, scale them, cut them into parts that fit on their printer bases, and add the required motor and parachute holes? In any event, the Mercury capsules might be nice at 4" high:


Wednesday, July 23, 2014

"Terror in the Sky" Airfest (updated with a discussion of tolerances in design)

Braving the 100 degree humiture, I traipsed out this afternoon to a local park to fly a couple of low tech water rockets and my Blade 180-QX Quadcopter. My drone piloting skills suck...hence the name of the 'launch'.

Things started poorly when I realized I hadn't reloaded the battery in my camera. And I had gotten all fancy by bringing out the tripod. Rats!

Water rocket-wise, I mainly wanted to see if the 1980's vintage hand held water rocket, which I adapted to the Quest launcher, would be suitable for the grand rocketeers.



As expected, this small volume pressurized fast with my electric pump.  Faster than I had hoped for. 50 psi was the lowest I could get it and I ran up to 100 psi.  The performance was unimpressive and I am a little scared to run those pressures around kids. So, this will be retired.  At least the old rockets are tough. My kids bounced this one off the pavement more than once before the pump gave out. The new models are not nearly as robust...at least not the $2 variety. This was a CATO, not a lawn dart:

20140719_104728

I also brought a 1L rocket with the Quest fins and bumper. This is where things went down hill.

I had recently bought some replacement nozzles knowing I was going to chop one up for the rocket shown earlier.  Well, something was up with the nozzle/launcher.  I flew several times at 80 and 100 psi. Most of the time, it wouldn't release without some nudging from my thumb. Not good for seeing the flight or staying dry. Glad I brought safety glasses. Once it launched spontaneously at 100 psi. Then it needed nudging again. I'm going to measure the nozzle and maybe lube it lightly?

At that point, the heat got to me and I scrubbed the quadcopter practice. Probably was a little too windy for this novice anyway.

UPDATE:  Well, I investigated the Quest nozzle issue further. This is all qualitative since I couldn't detect any differences with my calipers. Variations were beyond what I could reliably measure.

  • Original nozzle that came with the kit and is now on the red rocket above.  This is clearly the loosest fit.
  • The one that was on the other rocket that I flew. This was much tighter as it was full seated in the launcher. It slides in and out much better once it was lubed.  Is it loose enough?
  • The second new nozzle that I tried slides in and out easily. Very close if not the same as the original.
  • The third new nozzle was the tightest of all! I removed the O-ring and is was still just as tight. Enter the Dremel. Now that it is ground and lubed it its loose. Loose enough?
It appears there are variations in the molding process, possibly in the thousandths of an inch. My next solo outing will include testing all three of the new nozzles.

Tuesday, July 22, 2014

Cohete Gigante (a.k.a. Son of The Dude)

A while back I bought one of these for the grand rocketeers - $1.50 at Michael's. It is a rocket shaped Mylar balloon. The fins are held on with 2-sided tape. I glides pretty well and is indoor safe (i.e. light). On the drive home the gears spun up to speed and I decided I wanted one for my own devices.



When I got mine, it was on sale half off. I fashioned a card stock and foam board mount with a 24mm motor hole. This slides on the back end and holds the fins. The thing is so light that this extra weight brings the CG to almost the middle of said motor mount assembly. Per Rocksim, I needed about 2.5 oz to get it stable. To this end, I poured lead shot along strips of duct tape, folded them over and taped them to the front. The resulting 42" long, 4.5" diameter rocket comes in at about 5 oz unloaded.

This real time build is not iffy. I wanted to fly this on a mild D5 but it it a tad heavy and draggy. I'm worried the the Mylar body will buckle under even a D12. Then it is now nose heavy enough to lawn dart. I may yet try the D5 and see what happens. It will fly off a high power pad.

Local Nike Ajax display

The attached photo is the upper stage of a Nike Ajax, which is on display at a local high school. They are the "Rockets', due to a Nike Ajax battery that was located nearby. When the school was rebuilt, the missile was removed and refurbished. A shop class painted it the school colors vs. its natural scheme. I don't know if the missing fins are due to vandalism or just to make mount it easier. I don't remember how it was mounted before it was relocated.