Scratch - Skylark {Scratch}

Scratch Skylark Original Design / Scratch Built

Scratch - Skylark {Scratch}

Contributed by Matt Gillard

Manufacturer:

(Contributed - by Matt Gillard - 09/29/08)

scratch_skylark-mmx Brief:
A downscale of a British Skylark sounding rocket, designed on SpaceCad version three. A very high flyer as it’s a minimum diameter MMX motor rocket. Built for the EMRR 2008 challenge.

Construction:
Parts used were:

Handmade balsa cone
Polymorph nose cone
Body tubes BT 2.5
Three cardboard fins
Kevlar® thread.
Map pin

To build the kit I used:

CA gel glue
White glue
Model knife
Enamel paint
Black marker pen

I’ve never really been into scale modeling so this was a new challenge for me. I have a few sport scale and scale rockets such as two PMC V2s, an A-9, a Redstone, 2x Saturn V, Little Joe II and a Terrier Orion. I spent a good few hours looking for a rocket that I could reproduce within my abilities, had not been done as a kit before and hopefully made a bit closer to home. British rockets are limited. Initially I set about trying to copy a Congrieve rocket. But as this was a Neapolitan warfare rocket, it did not have fins and used a stick for guidance, SpaceCAD only allows a minimum of three fins. My final choice was a British Skylark sounding rocket. Internet searches yielded several articles about the last launch of a Skylark and several video clips of the rocket firing, but always at a distance and with nothing close up that I could get measurements from. Eventually I found two scanned pages from Peter Alway’s book “Rockets of the World” on the Skylark, although it did not say which version of the rocket it was. I intend to build a few versions of the Skylark, including one with a Raven or similar booster. The first version is this MMX version.

SpaceCAD is very easy to use, although I have never used Rocksim to compare it against. I have SpaceCad version three. Entering the data is quick and not at all difficult. Within 10 minutes the design was complete, luckily enough it was stable.

Space CAD

The nose cone was sanded out of a balsa dowel. The fins cut out from the cardboard back of a reporter’s notepad. The body tube was from a Fliskit rocket. The rocket was built in under an hour. With the mass being so low, I went for break apart or nose blow recovery.

There were no reliable images of the Skylark that gave any markings. To make things harder, the Skylark seems to change its look a few times, especially as other countries bought it. In the end, I found a model rocket that someone else had scratch built (I had hoped I was the first) and went for his paint scheme.

The balsa was sanded sealed and resanded.

One coat of grey primer. Two coats of white enamel paint. Black felt tip marker for the fins and surrounding area. The rocket was finished off with two coats of silver spray paint for the nose cone area.

scratch_skylark-mmx_tubelaunch Flight:
Given how small the rocket was, I decided not to add a launch lug and use a tube to launch the Skylark from. The rocket was launched on a calm day and with more luck than skill, I was able to catch a photo of the Skylark coming out of the top of the tube. It seems to be tilting off to one side which probably explained what I heard. The rocket seemed to be unstable and moved about the sky. I heard the ejection charge fire about thirty feet to my left and approx a hundred feet up. I saw it just as it landed. With the light mass of just over two and a half grams lift off weight means I’ll probably never get to see a MMX Skylark flying.

SpaceCAD suggests a height of 180 foot. I doubt that it got that high. Also, it gave the stability at just over 1 caliber. As the rocket was unstable, SpaceCAD's calculation was wrong.

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