Level 2 Certification

My Level 2 rocket is an extension and enhancement of my Level 1 rocket. Details of that rocket are on my Level 1 page.

(test flights)
(cert. flight)
NameRadio Flyer
Diameter10.2 cm (4 in)
Length192 cm (75.6 in)
Rail buttonsTwo 1010
Motor mount38 mm
Parachute (drogue)45.7 mm (18 in) nylon
Parachute (main)147.3 mm (58 in) nylon
Mass2992 g (no motor)3547 g3643 g
CP147 cm
CG (at launch)122 cm123 cm
Caliber (at launch)2.52.3
Thrust-to-weight (average)9.010.8
Thrust-to-weight (end of rail)13.318.3
Speed at end of rail22.9 m/sec28.7 m/sec
Apogee772 m873 m
Vertical speed at landing6.3 m/sec6.4 m/sec
OpenRocket fileZephyrMRM-L2.zip

I was very happy with the Apogee Zephyr kit and wanted to do dual deployment for my Level 2, so I ordered Apogee’s Dual Deployment Conversion Kit, which consists of an avionics bay, a drogue chute and protector, and an additional body tube to hold the main parachute. Another well thought out kit, although I was surprised they didn’t go with forged eye bolts. That was easily fixed, though.

Apogee Dual Deployment Conversion Kit (Apogee Components)

The avionics bay build was simple, so the avionics themselves were the main action for this build. I went with redundant flight computers from different manufacturers: primary is the Featherweight Blue Raven, secondary is the Missile Works RRC2L.

The Blue Raven is an amazingly capable device in a very small package. It can control four events, and collects a massive amount of data on each flight. Configuration and data download are via Bluetooth and a well-done smartphone app.

The terminal block on the Blue Raven is tiny, so I also ordered an Additive Aerospace Simple Circuit Terminal Expansion that brings the Blue Raven pins out to larger terminal blocks and in a more traditional layout.

The RRC2L is a simpler altimeter with a very good reputation around here for reliability.

I plan on all research avionics for my next rocket, so I decided against buying a COTS GPS tracker. A Transolve Rocketry MiniTransBeep will help with finding the rocket in the tall grass.

Everything is staked in accordance with NASA-STD-8739.1B (in the spirit of, anyway).

The batteries are secured by zip ties and wooden blocks glued to the sled. There is a very interesting article on the results of testing a bunch of 9V batteries at the Missile Works site: https://www.missileworks.com/9v-success.

Bulkhead (aft)
Bulkhead (fore)

Deployment test #1. There are three 2-56 nylon shear screws at each of the two separation points. The drogue is an 18″ nylon chute, main is a 58″ nylon chute. I used RockSim’s recommendation: 2.5 g for the drogue, 1.5 g for the main. The ejection test was exciting, too exciting! The nosecone remained attached after the drogue separation event, though. I’m going to try again with 2.0 g and 1.0 g. Also, some of the shear screws didn’t shear, they bent and pulled out of their holes. I’m going to reinforce the holes to try to get shearing.

Deployment test #2. Holes for shear screws resized and reinforced with CA. All the screws sheared perfectly this time. 2.0g of black powder turned out to be great for the drogue separation. I tried 1.0g for the main, but that wasn’t enough. 1.5g seems to be perfect. The only bad news is that I got the drogue in its Nomex protector too close to the ejection charge; the charge blew a few little holes through the Nomex and melted a few holes in the drogue. They can be easily patched, though. Next time, lots of dog barf!

According to OpenRocket, the flight profile with an AeroTech I284W looks like:

Flight Profile with AeroTech I284W motor (OpenRocket)

And this one I painted!

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