I picked up two LOC 4" nose cones, 38 mm centering rings, 3/16" 4 ply birch plywood, and two 4" dia paper tubes cut to 6" lengths. First construction step was to glass the body tubes with two wraps of 2 oz. SIG fiberglass.  Then I cut the fins and cut the tail cone and the nose cone. Built the Altimeter bay and finally, assembled the rocket. Easy as igniter wire laced thermalite eh.

Follow my construction below.
 

It sounds easy - just cut off about two inches off the top of one LOC 4" nose cone. Use a piece of 54 mm motor tube as a marking guide. Slip the motor tube over the nose and trace around the edge. Viola a 54 mm opening. The hard part is actually doing the cut. HACK. I traced the line with a pen knife first, and then scored the cut deeper with a hacksaw. Save the clipped nose piece for the shock cord mount. Also, cut off the shock cord mount side of the cone leaving only 1 1/4" of the shoulder.
 

Since I was now a pro at cone cutting I turned to cutting the other LOC 4" cone for the fins. Cut the fins first to make sure the fins match the tail cone cuts. The original V2 article includes fin templates and a template to the wall cut. I used the fin and traced it onto the tail cone instead. I used 3/16" 4 ply birch plywood for the fins.. I traced the fin outline and cut the fins on my trusty router / jigsaw table. Cut the 38 mm motor tube to 11 inches. Enough for over hang at the top and bottom of the tail cone..
 

The motor mount and fin can are one in this model. No building the mount and then insert into the rear.  I used two old rings lying around to make this mount. First I sanded a 1/8" 2.56" 29 mm ring into a 2.5" 38mm ring. Then I sanded a 3.9" ring down a little to just fit inside the lip of the fin can. The rings are spaced to just fit the fin edge and to make contact with the motor tube. (The lip is the area just inside the cut off shock cord mount.) This created a  recessed area in the fin can of about an inch. All the more room for cord and chute. Add in a "u" bolt and there you have it.
 

Using a LOC 4" nose cone, cut off the existing shock cord mounting area. Leave at least a 3" shoulder on the cone. hen use the 2" long nose portion clipped off earlier - run a 1/4" x 8" eye bolt through the old piece and secured it with washers and nuts. Next, rough up the forward end inside of the nose cone with a rasp. Epoxy the eye bolt assembly into the forward end of the nose cone.  The assembly provides extra mass in the cone typically needed with a V2 and it provides space necessary for the main parachute in the payload compartment.
 

 Top View of Altimeter Bay
 in Payload Section

This was the whole trick to the project. I decided early on I wanted to do this as a dual deployment rocket. The problem being space. I somehow had to retain a 12" body tube length. So I crafted a 3" altimeter bay in a 6" paper tube coupler by laying the altimeter on its side. I am using an Olsen M2 altimeter which has a barometric G switch and not mechanical launch detection. It is sized just right to mount and lay on its side. Also, instead of mounting the ejection can exterior to the can I am mounting it opposite the altimeter. I epoxied in an 18 mm motor tube to hold a Blacksky safe eject can. I would like to add a remote safe switch. Assembling the bay I will use thin dense foam strips to help seal off between the altimeter mounting board and the eject can area. ( In the photo at left the eject can will mount in from this side and protrude down out into the payload half). 

Construction was with a 6" paper coupler. Mount half way in the coupler a 3/16" bulk head cut for the inside of a coupler. That will be the top of the bay. The bottom was crafted gluing a 1/8"x3.9" bulk head plate (cut for the inside of a coupler) to another 1/8"x3.9" bulk head plate. This will be the bottom of the bay. Add U bolts, two all thread connecting rods, and top with wing nuts.

Note the photos at left. The upper photo is the coupler upside down. The bulk head plate is only half way in the coupler. The second photo shows the payload section right-side-up. The payload body tube added on. There is 2 3/4" depth in the payload section down to the coupler plus the 3" of coupler to the bulk plate.. The nose cone shoulder has been cut to match the 2 3/4" depth.
 

It is a tight package - but that is the design!

Total weight with chute, cords, protectors, quick links and altimeter is 54 oz.

5/21/01

Day two of the National Sport Launch NSL2001.
I loaded a Dr. Rocket 38/600 case with an I-284w-14.  This motor will really power the rocket up. next I loaded a BlackSky Easy Eject Canister with an igniter wire and 1.5 grams of 4f. Setting these aside I set the Olsen altimeter for the flight.  The Olsen works great in this situation as I have turned the altimeter on its side to fit in the 3" deep altimeter bay. I programmed the unit to activate upon barometric pressure change instead of "g" switch.  Attach all parts together and load the 30" drouge and 45" main chutes, cords and altimeter bay. Ready to launch.