During the construction of an RV-6A quick build kit, EPM.AV was confronted with the classic problem of "How do they keep hot vapors and flames out of the cockpit should a fire occur in the area of the engine/cowling?"
Aluminum is definitely not suitable for this function since aluminum loses substantial mechanical strength in the temperature range 500°F to 600°F and melts in the range of 1220°F. Stainless type 304 exhibits good structural service at 1600°F and a nominal melting point of 2600°F.
They conducted initial high temperature studies of 304 stainless as a replacement for aluminum units currently available. These test results were quite clear and pointed them in the direction of producing an all 304 stainless steel heater valve. NO thin wall stainless tubing in the thickness range of 0.025" or less was found. In fact, standard small stainless tubing starts an an O.D. of ¼" with a wall thickness O.D. of 0.035".
The final solution was to create their own thin wall 304 stainless tubes and flat sections. The initial shapes were formed with hardwood tooling to create proof of product concept parts. At this point a new group member Paul Bowmar, an experienced machinist and tool designer, stepped in to design in house permanent hard tooling. Paul also initiated experimental high temperature testing of the initial 304 stainless products and previous aluminum parts using a 1200°F to 2000°F propane blowtorch impacting on a stainless firewall mockup.
• All parts are 304 STAINLESS STEEL, increasing
safety in the unfortunate event of an engine fire.
• Tube has lip to ease attachment of scat tubing.
• Tube has hose bead helping to resist detachment of
scat tubing.
• Cross drilled control cable attach bolt included.
• Spot welded for strength and integrity.
• Same bolt pattern as aluminum unit sold by kit
builder.
• Easy replacement. |
