7/14/2023 0 Comments Micro warbirds rcNote also that some glow engine props can't easily be trimmed because of material their made from so be sure to check prop manufacturer's recommendations and warnings before trimming. A bench test set up helps with the work to optimize prop selection. Be sure to ALWAYS balance your props, particularly after trimming. ![]() Because of prop efficiency losses I tend to go a little high and trim prop diameter back. Using the 7x3=21 prop example, increasing 21 by 16% yields a disc of 24.4. To account for this factor, I tend to round up to the next available diameter and/or next available pitch. This disc can be increased by at least 16%.actually more because of prop efficiency factor - losses. For example, if a 7x 3 prop was used at sea level the prop disc is 7x3=21. In your case, using the same prop at elevation as at sea level results in an approximate 16% reduction. I fly at 6,500 ft MSL in Colorado and this method works for me.įor our purposes, power (thrust) and velocity decrease with altitude (elevation) proportional to the square root of the ratio of air density at sea level to the air density at elevation. In your case, flying at 10,000 ft MSL the following might help with your prop selection. As a note, this is also reason for the gull wing - to provide additional ground clearance for the prop.įor our models, 3 and 4-blade props are sometimes difficult to get in the proper size, and always more expensive so using a 2-blade prop and increasing diameter and/or pitch to suit power available is often the choice. ![]() Engine was so powerful a 2-blade prop had to be too large a diameter to use power available that the 2-blade prop would hit the ground so they changed to a 3-blade prop of smaller diameter. ![]() what the 2-blade prope would be because you're adding 1/2 or doubling the capacity with the additional blades. However, a smaller diameter is typically used vs. Convention is for higher power available from the motor, using a 3-blade or 4-blade prop will provide more thrust than the 2-blade prop. Effect of additional blade is as your test demonstrates - more thrust.
0 Comments
Leave a Reply. |