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Michael and Gayle's RV-7A
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Date: 6-22-2008
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Number of Hours: 4.00
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Manual Reference: 10-2
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Brief Description: Brake line to Brake cylinders
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Ran the short piece of tubing to finish connecting the brake lines to the brake cylinders. This step actually caused quite a bit of research regarding the proper brake fluid as well as validating if the brake assembly from Van's would be correct for this aircraft. The easy issue first: Found the correct fluid to be: Royco 782-1GL (meets MIL-H-83282), available at: http://commerce.acilubes.com/SearchResult.aspx?CategoryID=7 in gallon size for ~$35.00. Now, to make a long story short, I've decided that I will upgrade the brake assembly (shortly after the Phase1 period -- prior to full loads) to the 30-181 specs. This aircraft's gross weight will likely be in the 1875 LB range.
Here are some calculations from Cleveland Wheel and Brake (CWB):
KE = (.0443 x W x (V x V) ) / N
Where: KE = Kinetic Energy per wheel-brake assembly (FT-LBS); W = Design Landing Weight (LBS); V = Aircraft Speed in Knots. V must not be less than VSO (The poweroff stall speed at sea level, design configuration); N = Number of wheels with brakes. From Van's with RV-7A finish kit: Brake Assembly Ship Set number: 199-102. KE capacity per wheel-brake = 117,500 FT LBS. Note: Van's RV-7A VSO at Gross weight of 1800 is 58 MPH or 50kts.
Example 1: W = 1875lbs, V=50kts (58mph), N=2. Required KE per wheel-brake = 103828 <=== Okay with Van's parts. Example 2: W = 1875lbs, V=53kts (61mph), N=2. Required KE per wheel-brake = 116661 <=== Okay with Van's parts. Example 3: W = 1875lbs, V=56kts (64mph), N=2. Required KE per wheel-brake = 130242 <=== Exceeds Van's parts!!! Example 4: W = 1875lbs, V=61kts (70mph), N=2. Required KE per wheel-brake = 154538 <=== Exceeds Van's parts!!!
For the upgrade, see Wicks URL: http://www.wicksaircraft.com/catalog/product_detail.php/pid=4614~subid=2951/index.html.
The KE per wheel-brake of CWB30-181 is 155,000 FT LBS. Also, at the same time, upgrade the Brake caliper seals to Viton 2-218V-75 available from: Ace Seal Inc http://www.aceseal.com in Santa Clara, CA.
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Right brake line down gear leg to brake cylinder
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A closer view
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