Inside detail showing fin attachment
This rocket is being built in memory of the J-eater that was lost.
It is being constructed with a large 6in mount so I can fit it with many adaptors.
I will start by making two adaptors. One will have a single 3in MMT.
The second will be a cluster of 4 54mm MMT's.
Target weight is 20lb.
This is a link to a PDF drawing of its design(14.3kB)
Summary:
This is a basic 3FNC design.
It will have two 7.5in phenolic tubes for the body, each with a single wrap of fiberglass.
I will put a wrap of Kevlar on the end to make them zipper resistant.
The 1/4in fins will have a layer of CF on each side with fiberglass going tip to tip across the MMT.
This fin unit will be inserted into the BT which will have slots cut on my table saw.
The MMT is a 2foot long piece of phenolic tube.
Fin shape is my
standard modified trapezoid
so they have good strength to weight ratio and security in landing damage.
Rail guides will be installed using blocks glued to the upper and lower CR.
I will use a 7.5in coupler that mates the two tubes together.
This will have a bulk plate made for each end out of 1/2in ply.
These will have a 1/4in step in them so they seal the tubes.
Each bulk plate will have a u-bolt for harness attachment.
There will be two 1/4in threaded rods running through each bulk plate to hold them to the bay.
I will glue tee nuts to the inside of the bay so the upper
BT can bolt in place.
Fin can:
Because this rocket has a 6in MMT inside a 7.5in BT there was not alot of tab
inside the airframe.
Since there was not much tab I decided to reinforce the
inside using kevlar strips placed over the fillet at the fintab/MMT joint.
I
added this after I glassed the fins tip to tip across the MMT.
Inside detail showing fin attachment
Also because there was little space between the MMT and BT there was no room for a U-bolt so I used a loop of kevlar glued to the MMT and reinforced with a piece of kelvar.
Detail of harness attachment