I just posted several videos to the Rocket Calculator site demonstrating how to use many of the calculators. The videos are from version 1.3, which should be available within the next week. This upcoming update has the following changes:

• Input option for elevation and temperature to compute correct air density. Used in altitude prediction as well as parachute and streamer descent rate calculators.
• Changed altitude prediction calculator input field ‘Motor case mass’ to use ‘Total motor mass’ instead. This was more intuitive, allowing the user to enter initial motor weight and propellant weight.
• Changed default descent rate for streamer calculator from 3 m/s to 4.5 m/s.
• Added missing Cesaroni motors.
• Changed app icon.
• Changed app-launch image.
• Minor bug fixes.

Here’s a pic of the new icon.

The App Store approved my latest update yesterday. This adds a motor look-up option to the Altitude Prediction->Data Assistant screen. It also fixes a minor issue on the Static Pressure Port calculator screen.

Here’s a screen shot from the motor look-up screen.

My latest update was just approved for the App Store. This adds a body tube look-up feature to the Altitude Prediction calculator. There is a new button on the Data Assistant screen which will provide a list of tubes to pick from. After selecting a body tube, the tube’s diameter and area will be populated back to the Data Assistant screen. I’m working on a motor selection feature too. I hope to have that out soon.

Here’s a screen shot of the body tube selection screen.

Here’s video from two cameras of epic fail 3.

Against good judgement I made a third launch attempt (I was bored waiting for the phone company to fix my DSL). I had four Q2G2 igniters left, so I dipped the tips in pyrogen. I then attempted a wadding tape method, which I think worked fine, but probably taped them in too well.

I wired them up and used my Go Box. All igniters lit, but only three motors fired, and they didn’t all fire at once. It got hung on the pad while the first two burned. Then the other two igniters lit, with one motor firing, and the other pulling out too early. At this point it left the pad.

I really need to build the relay launcher. (And order more igniters and motors) The three motors that fired blew out of the back too, so my retention method needs work. I don’t have enough spacing to wrap tape around the motors and mounts. I have some tiny screws and nuts than might work. I would need to dremel off the head of a screw and glue between the four motor tubes, then screw a nut on after the motors are installed. I haven’t checked the fits yet, but is what I’m going to look at next.

I had a great first flight. The video stills aren’t too great. I used my Aiptek 720p video camera with lens set for macro. I think it was set a little too far back. Here is video and liftoff shots:

I finished the detailing and re-did my launcher to accommodate clustering. After re-checking CP in Rocksim, I added 3 grams of weigh to the end.

This affects my predicted altitude by about 90 feet.

I made two launch attempts, but each time only one motor lit. I need to reworking my clustering arrangement again. I will probably make a tiny clip whip, or wire a bunch of clips to a terminal block mounted on the launcher.

I don’t have a lot of streamer stuffing room. Originally I wanted to use 1 3/4 in crepe paper, but had to cut it down to 1 1/4 in. I originally calculated an 18.64 ft/sec descent rate with a 20 in x 1.25 in crepe streamer.

After adding the nose weight, and using the same streamer I should get a 21.31 ft/s descent rate.

Here are all the pre-launch pics:

Motors loaded:

Next to the deuce:

The new launcher:

I originally estimated 344 ft.

After adding nose weight, I should get only 253 ft.

Here are some pics of the failed flights. They still look pretty cool with only one motor going (at least for the first 10 feet).

Flight 1:

Flight 2:

The rest of the build went really well. I still need to finish it. Here are some pics:

Nose cone fins:

Booster square to round transition. For a detail description of my convoluted method to produce this see here:

BT2.5 booster tubes:

Booster assembly:

Making a BT-4 coupler:

Tapered 1/16″ basswood:

Bottom wrap:

Motor blocks:

I started working on the micro scale Nike Hercules. I ordered most of the parts from Fliskits.

I plan to fly the full stack as a single stage, four motor cluster. I did install a motor mount in the sustainer in case I figure a good way to stage it. I might fly the sustainer by itself if it’s not too heavy.

Here are some pics of the build so far.

Rocksim images:

The motor mount/tail cone assembly parts:

I steamed the tail cone wrapper to help form it.

Motor mount: (I’m getting used to these tiny parts)

Some pics of the tail cone assembly:

The new Fliskits NCB-5K nose cone is pretty close to the shape and length I needed.

Roughly holding it together here:

Fins:

I’m finally making use of my Ulf’s fin jig:

Starting to look really cool:

Bottom fins:

This will fly as a single-stage, 4-motor cluster. I’m leaving a motor mount in the sustainer in case I figure out a way to stage it.

I designed a MicroMaxx powered Nike Hercules. I only have the sustainer so far, but will add the rest soon. I have most of the parts to build, the rest are on order. The Rocksim file is available in the downloads section. I also have some templates on Google docs. The titles on the parts list aren’t all correct. For instance, the nose cone is the new Fliskits NCB-5K, but on the list it’s adding Sunward. Anyway, no big deal. The dimensions are there.