|Jan 24, 2013, 01:48 PM|
Electric Retract recommendation needed
I am building a 40-sized trainer and would like to put electric retracts in it. I do not have any experience in this area (retracts), so I could use some specific recommendations.
The issues that I see are:
- tricycle gear
- the mains are splayed and attached to the fuselage
If possible, I would like for the gear to splay outward in the "down" mode and retract up into the fuselage in the "up" mode.
Here are a few pics to help you...help me.
|Jan 24, 2013, 02:59 PM|
Is that the F-14 "TameCat"?
I finished my G/P F-15 last spring and tried to work out the geometry for retracts with no success. Nose gear was no problem since I moved the fuel tank to the CofG, but the engine nacelles were not large enough to fit the main wheels if I wanted to follow the original wheel track width. With the angle between the gear legs and axles the wheels come into the wells on an angle. the G/P F-14 has wider nacelles large enough to accommodate that angle. A multi-link setup to maintain wheel alignment was the only solution, but deemed far too complex for this model and hard to rig with servoless retracts.
As for the proper set of servoless, you have options based on aircraft weight and sweep angle. Most common I've seen are in the 85-90 degree, with I believe 100 degree also available from some.
I'm a big fan of E-flite servoless as the larger 60-120 units capable of working up to 15 lbs use strong alloy frames. I would imagine your 40 size craft would be in the 6 lb range and you should be able to work with the more common plastic frames up to that.
I do have a set of mains only RCLander retracts capable of up to 13-15 lbs. Basically new other than I countersunk the mounting holes. Their motor orientation did not allow them to fit the intended application.
No struts on mine, just 5mm wire.
I'd be interested to see if and how you solve this one.
|Jan 24, 2013, 03:27 PM|
Yes, that is the Jeff Troy's F-14 TameCat 40 trainer. It has yet to be built, but I will be doing an electric conversion and would like to work in retracts.
|Jan 25, 2013, 09:38 PM|
helped a little, but not much. It probably would have helped someone with a bit more experience or knowledge, but that is not me.
Flying weight is 5.6 lb / 2560 g / 2.56 kg
I was thinking that I would need something like this (since the main gear is splayed), but I really have no idea. I'd hate to make a $150 mistake.
|Jan 27, 2013, 06:28 AM|
Try something as a pattern first to see if the wheels actually fit. I formed a simple wire leg with the angles that had the wheels in the original position, then working backwards tried altering the retract mounting angles, location and geometry to have them fit within a general area of concern.
Basically that meant to start I bent a wire identical to stock, at least at the bottom. I had the fuse inverted with a cardboard former off the wing to indicate where the stock main wheels were designed to be, then bent the upper angle in the wire to simulate the main legs of the retracts. Holding them in that axis I would swing the legs through 90 degrees and watch what happened when the wheels came up. This is how I discovered the wheels/axles angle required at the start interfered in the retract position, regardless of where and how I mounted the retract units. That angle was not set in stone and was varied, (and if you get multi-link geometry units this is moot) all with the intent the main wheels would at least be close to original location. You may vary track width a bit, but always try to have them stay at the same height and station to continue the ground handling of the original.
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