MotionRC FlightLine Corsair design flawAuthor: Dave Date: 04.10.24 - 8:58pm So the MotionRC FlightLine 1600mm F4U-1A/D Corsair retracts landing gear (SKU: FLW304082) is a pretty fragile design. A friend has already gone through like 5 of these in 5 days of flying :( The flaw lays in the cross pin you see sticking out of the main shaft. This pin presses against the side of the case and rotates the tire as it comes out of the body of the plane. The flaw is the pin is to large of a diameter leaving to thin of a side wall on the main shaft and it will break off very easily. The main shaft is quite a hard steel which also leaves it brittle. Maybe this was designed as a tear away part to save the structure of the wing, not sure, but at $22 a pop, its just to fragile. I contacted support to see if just a replacement pin was available. Seems like buying these in bulk would be reasonable, but only the complete unit is for sale. They are also frequently out of stock since everyone is breaking them :( Soooo, we are playing around with redesigning the part some. Below is the replacement we came up with. Common grade of cold rolled steel with a 1/16" roll pin. I cant see it breaking again at this spot, but will see if it shifts the damage to some other part of the plane or if its a win. I will update this post as we experiment more. Below are some picts and dimensions. Not hard to fabricate, just a bit fussy with the small dimensions. Also worth mentioning, if the side you need is out of stock, only the die cast block has a R/L side to it. Everything else is interchangable so you can swap pins with your broken one and get back in the game. 
If you are putting one of these on a servo tester, the electronics will trigger with only a min or max signal. Then the device will operate fully until it reaches its limit switch and stops. I might need to put a bushing around the rollpin to bring it back to the expected 3mm diameter to keep the wheel rotation correct. In practice the diameter difference of .12" vrs .0625" or .030 per side probably wont matter. Time will tell. Unfortunately the relief on the die cast block doesnt give us any room to enlarge the hole for a larger main shaft. You would need some 1/4 steel rod, a 2.5mm tap, metal lathe, 1/16" roll pin, calipers, and a file to make this part. Comments: (0) |
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