Angelfire Recovery

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Click on any photo below to see a larger image of it.

The recovery harness flame shield for Angelfire was cut from a bolt of 8 oz Kevlar cloth. This photo shows how I used a metal pin, a string and a Sharpie pen to mark the cloth in a circle.

I got the Kevlar cloth from Thermostatic Industries, Inc. Their part number for it is 8K-60. It was $100 for 3 yards x 60 inches (45 sq ft). To cut Kevlar cloth I use some special shears that look like scissors and are available from CST for $17.95. (Part number E814.) They work really well!

The outside edge of the flame shield was sewn with an overcasting stitch that prevents the raw edge of the cloth from fraying.

I got my Kevlar thread from McMaster-Carr. The part number was 8800K81. It is trade size 69, 0.014" diameter, 375 yard/spool for $13.50.

Two tubular Kevlar anchor straps pass through a small hole near the edge of the Kevlar flame shield. Then a water knot is tied into each end and some epoxy is added to the loose ends to keep the tubular Kevlar from fraying. A triangular metal "quick link" is added to each end to allow connections to the U-bolts inside Angelfire. The tubular Kevlar webbing is available from various rocketry vendors for about $1.25 per foot. One such vendor is Giant Leap.

The triangular metal "quick links" shown above are type 316 stainless steel. They are 1/4" material and available from McMaster-Carr as part number 3709T33. For the main parachute harness (not shown) I also used a square "quick link" connector with 1/4" material, also from McMaster-Carr. It is part number 33785T65.

A simple water knot is used to create a loop in the end of the tubular Kevlar anchor strap. This photo shows the first step in tying that knot. Double the end back along the strap for about 6-8 inches.

Then just execute a simple overhand knot and pull all the webbing neat and tight. The loose end is then just touched up with some epoxy to keep the Kevlar from fraying. The knot itself is very strong. Don't add epoxy to the knot itself.

I used 1" wide tubular nylon (TN) for the drogue and main parachute harnesses. Again with a water knot tied into each end as shown here. (The photo shows the knot just before it should be pulled tight.)

The drogue harness uses about 50 feet of TN so that the two halves of Angelfire will separate by a large distance and hopefully slow down a bit before the TN comes tight. The long length also helps give a low probably of them hitting each other. The drogue is a SkyAngle 24" drogue parachute.

The main parachute (not shown) is a SkyAngle Cert-3 XL. It only needs about 15 feet of the 1-inch TN. This is plenty long enough for the nosecone to hang below the main parachute without hitting the body tube. The nosecone is connected using a four foot length of TN.

The main parachute is also wrapped "burrito" style in a large rectangular piece of 8 oz Kevlar cloth to protect it from the flame and heat of the black powder ejection charge. (Not shown).

Shear Pins

Angelfire uses three small nylon "push-in rivets" as shear pins on both the drogue and main parachute compartments. These rivets come from McMaster-Carr as part number 90218A116. They are designed for a 0.128" hole diameter and are 0.330" long. This seems to be just right for Angelfire. The rivets must extend through the body tube wall and the coupler tube wall.

Here is a close-up view. Some places call these things "canoe clips" or "arrow clips" because of their shape.

The head on these clips does not protrude very high so they mount fairly flat against the body tube. They can also be removed if needed.

Here we see a rivet ready to be installed into a hole in the body tube.

Half way in.

Rivet fully inserted. The head is down tight against the body tube.

Angelfire uses three rivets for the drogue and three rivets for the main parachute compartment joints. Ground testing showed that 4.5 grams of black powder was optimum for both compartments. It gives a nice forceful ejection without being too violent.

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Click here to see how Angelfire was painted and how the decals were applied.