Mach-1 Industries Hawaiian Sling Plan

Mach-1 Industries - Hawaiian Sling {Plan}

Contributed by Keith Smith

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstar_borderstar_border
Overall Rating: starstarstarstar_borderstar_border
Manufacturer: Mach-1 Industries

PlansBrief:
This is a single stage rocket with unusual deployment. 1/8" ID tubes conduit the ejection charge from the sealed main BT to three pods on the end of 3" fins where there is a 12" chute in each pod. The nose cone does not come off.(click picture to enlarge)

Construction:
The biggest problem with this model is buying the 4" length, 1/8"id tubes to build the 'deployment' system. I ended up getting the three 4" 1/8"ID tubes from Sigma Rockets in Canada. I have yet to find another supplier as I plan to kit up three more rockets. The BT-60, BT-50 tubes, the BT-60 nose cone, BT-50 nose cones and shock cord are easy to get.

I used paper centering rings reinforced with epoxy. Paper centering rings are easy to find. One can order the 'balsa ply' sheets directly from Mach 1 or Balsa Machining Services. One can use RockSim, describe the fins and have them made by BMS along with the centering rings. The 'balsa ply' requires patience and care to cut square.

The most difficult construction step is slotting the tubes and cutting the hole for the ejection tubes. The hole in both the main BT and pod BT must be positioned such that the tube rests flat on the top of the fin, or you have to fill in the 'gap'. I numbered each slot and numbered each fin and fitted each one individually. One must make sure the hole is the correct size. Do not make the hole for the ejection tube too large. The pressure of the ejection charge will blow through any glue joint. I found out the hard way.

I used 30 minute epoxy for the entire model. This models weighs in at 10.5oz. A D12-3 is just right. I found after construction and before adding the chutes the model would roll when the 36" BT was laid on a table and fins allowed to hang over the edge. This roll indicated to me that the rocket might have a precession during flight. I added weight at the bottom edge of the fins, like adding weight to tire, to balance it. This is level 3+ kit due to the cutting of slots and holes in the body tubes.

Finishing:
This model finishes normally. I painted it the color of a Hawaiian T-shirt. In other words, lots of loud colors.

Construction Rating: 4 out of 5

Flight:
I was only able to get two flights. The first flight was perfect. With a D12-3, the rocket is right at the weight limit of the motor. The rocket roars longer because it doesn't go very high. The deployment saw all three chutes open and the rocket came down gently to the ground.

On the second flight there was no deployment. The rocket lawn darted into the ground, crimping badly at the nose and the motor mount. Examination showed that the ejection charge had blown through the BT at the tube joint. The ejection tubes were not extended into the BT enough as well as the hole for ejection tube no being made a good fit. I plan to kit three more models and try different techniques of sealing the ejection tubes and joints.

Recovery:
I used swivels on all three chutes and the deployment was perfect. No tangles and the three chutes did not tangle up with each other. I used Kevlar® shock cord and bowlines to tie the ends.

Flight Rating: 3 out of 5

Summary:
An unusual rocket. Definitely well designed, if built properly. Neat when it works. Bad when it doesn't.

Plans are at Mach1 Website (now out of business).

Overall Rating: 3 out of 5

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