7.5 Inch IRIS Project

6 hours of woodworking at my friend Jerry O'Sullivan's workshop.  Parts were in storage in my basement since 2005.

Dry fit of motor mount parts on the 6" motor tube.

Construction

Vacuum bagging the baltic birch fins which have been reinforced with a layer of 5.7 oz carbon fiber cloth and a layer of 3 oz fiberglass veil cloth.  This is where the work stopped on this project back in October 2005

Started working on this project again in May 2016.  Aligning centering rings with fin notches  Nuts and washers on either side of the centering rings for strength.

Closer look of the fin notches and centering ring joints.  3/8" fin root will need extra reinforcement!

Motor mount structure sitting on fin alignment template

Dry-fit of motor mount assembly

Tacking fins to 6" motor tube using JB Weld Clear Weld

Using a plumb line to keep the fins aligned.  Four 5/16" all-thread adapters epoxied into the aft centering ring and connected to the all-thread.  Will be used to secure motor adapters into the 6" motor tube.

Fins tacked to 6" motor tube using JB Weld Clear Weld

Fiberglass reinforcement tape before epoxy resin applied

Internal Fiberglast System 2000 epoxy fin fillets reinforced with fiberglass tape

Cutting fin slots in the airframe old school style.with a Dremel tool

External Fiberglast System 2000 epoxy fin fillets for strength

Successfully drop testing the strength of the recovery system attachment points in the zipperless design for the 37 pound lower section

Recovery system attachment points details.  5/16" all-thread passes through the entire length of the airframe.  Two are connected to the u-bolts via the pear shaped quick links.  Two are screwed to the bulkhead with cap nuts.

Inside removable electronics bay with electronics mounting board rails and 5/16" T-nuts for screwing sections together.

T-nut details.  Balsa used to conform to the curve of the airframe and to provide a secure place for the t-nuts to attach

Removable electronics bay with ejection charge holders and recovery system attachment points

Removable electronics bay with both sections of airframe attached.

Tube cutting jig for the airframe.  The airframe is rolled into the blade.  Stop block installed on left side of fixture to ensure 90 degree cut and proper length

Success!  The upper airframe is now the proper length to get the 62% scale or 150"  This is also the section of airframe that will create the payload bay for the main parachute and recovery system.

Safe/Arm switches to control altimeters installed in avionics bay. Switches are accessible through the airframe.

Fiberglast 1100 Lightweight Epoxy Filler used to smooth out the external fillets.

Internal view of avionics bay.  Extension wires on switch leads, altimeter mounting board installed and static ports drilled.

Ready for primer, paint and graphics.

Almost there!

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