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Old Sep 19, 2014, 08:12 PM
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Idea
Retractable Nose Gear for Floats

After previous unsatisfactory efforts, I started over in the effort to get retractable gear for 40 sized floats. This latest functioning mock-up actually seems to work and holds real promise. There are lots of details to resolve concerning installation, etc. but this one has functioned without flaw now for many dozens of cycles.


NoseGearVideo1 (0 min 45 sec)
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Old Sep 19, 2014, 10:03 PM
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# Scale is a way of life
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thought about engineering these too,, what locks it in the down position?
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Old Sep 20, 2014, 10:41 AM
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thought about engineering these too,, what locks it in the down position?
Hi Scale,
I will send some pictures a bit later. After trying everything else, I concluded that the guys who designed the full-sized retracts knew best.

The servo is Firgelli, connected to a hinge pin, which in turn is connected to a solid brass nose trolley. The hinge pin axle runs through the Firgelli rod end connector, and is supported on each end by 4mmx8mm ball bearing rollers.

The trolley has two axles, one fore and one aft, each also on bearing rollers. Exactly as in the full scale version, on extension, the trolley, which has the nose spring (strut) attached moves forward in the horizontal bearing channel, until the forward trolley bearing falls into the downward slanted channel. The aft trolley bearings follow the nose spring downward. The hinge pin bearing however does not travel downward, because of the hinge, but continues horizontally into a channel notch at the very end of the servo extension travel. The rollers in the notch provide the positive lock-down for the entire gear assembly when extended.

This is long-winded, but when I send the photos, the simplicity of it will be far more apparent. They sure do work, and every time without fail.
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Old Sep 20, 2014, 12:46 PM
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Here are a couple of photos of the side channels, with hinge pin, trolley, and one with the nose spring.

Note that these photos show the fore axle with slide blocks instead of bearings. I discarded the slide blocks and replaced with roller bearings in the working model.
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Old Sep 20, 2014, 12:57 PM
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A blurry top view of the pushrod operation working. I apologize for the quality.

NoseGearTopView (0 min 14 sec)
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Old Sep 20, 2014, 01:39 PM
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# Scale is a way of life
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Cool, thanks,, look forward to seeing how you waterproof the system,,,
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Old Sep 20, 2014, 06:14 PM
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Cool, thanks,, look forward to seeing how you waterproof the system,,,
After the previous projects it will be little challenge. It is also the reason the full-scale are built in a box just below the float deck. The box drains back out the nose, with a sweeper behind the stop block.
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Old Sep 20, 2014, 08:27 PM
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# Scale is a way of life
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in my mind's eye of preliminary engineering, I was thinking a Lado style jack screw with a longer threaded coupler that would have a non threaded rod area where an rubber grommet would separate the electronics from the wet "box" as you put it,,

those Firgellis are to pricey to risk getting wet,,

good work so far
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Old Sep 21, 2014, 08:58 AM
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I hope they work every time, and you remember to retract them every time if water landing --


Float Plane forgets "wheels up" when landing on water (0 min 11 sec)
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Old Sep 21, 2014, 10:24 AM
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I hope they work every time, and you remember to retract them every time if water landing --


https://www.youtube.com/watch?v=-48V1m_MZxE
Darn those checklists. Where did I put them?
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Old Sep 21, 2014, 10:36 AM
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Originally Posted by scale_only View Post
in my mind's eye of preliminary engineering, I was thinking a Lado style jack screw with a longer threaded coupler that would have a non threaded rod area where an rubber grommet would separate the electronics from the wet "box" as you put it,,

those Firgellis are to pricey to risk getting wet,,

good work so far
We tried to avoid the Firgellis because of the very high expense (About $90.00 for the long-throw, and $70.00 for little ones), but finally gave up, as the Firgellis solved so many problems. Of particular note, they have built in resistance stops which halt operation in case of obstruction without burning up the servo or damaging the gear. I haven't worked up the nerve to do the Corrosion-X soaking of my one Firgelli to test yet, but I believe it to be advisable no matter what other waterproofing procedures are undertaken.

We looked at jack-screws too for a bit, very doable, but requiring end-point switches, etc.

Haven't conquered the main gear design yet either, also discarding several attempts. As an additional challenge, the mains will require differential braking.
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Old Sep 21, 2014, 04:45 PM
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# Scale is a way of life
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We tried to avoid the Firgellis because of the very high expense (About $90.00 for the long-throw, and $70.00 for little ones), but finally gave up, as the Firgellis solved so many problems. Of particular note, they have built in resistance stops which halt operation in case of obstruction without burning up the servo or damaging the gear. I haven't worked up the nerve to do the Corrosion-X soaking of my one Firgelli to test yet, but I believe it to be advisable no matter what other waterproofing procedures are undertaken.

We looked at jack-screws too for a bit, very doable, but requiring end-point switches, etc.

Haven't conquered the main gear design yet either, also discarding several attempts. As an additional challenge, the mains will require differential braking.
Lado and Wingspan actuators both have built in electric end stops, no switching needed,, one actuator connected to both main and nose is what I envisioned

simple mains design here
http://www.ronleclerc.net/floats02.html

good luck
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Old Sep 22, 2014, 02:51 PM
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Lado and Wingspan actuators both have built in electric end stops, no switching needed,, one actuator connected to both main and nose is what I envisioned

simple mains design here
http://www.ronleclerc.net/floats02.html

good luck
Definitely need the luck, Scale, though it seems like I have made all possible mistakes so far.

Gaaack! those LADOs are more expensive than Firgellis! Though if you could design so a single actuator handled both nose and mains it would help alright. I am puzzled as to how it could be done unless nose and main rod throws were of equal length?
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Old Sep 24, 2014, 09:58 AM
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# Scale is a way of life
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in my mind,
if the actuator was mounted to the mains, then the jackscrew extended forward to the nose gear it would kinda float between them during the cycle. The mains have such a short travel, shouldn't be a problem. just needs clearance in the nose for the jackscrew when in the retracted position. The trolly would have to be engineered differently than what you got started, but in theory no reason you couldn't connect the mains the back to those Firgellis and let it float too, if they have enough travel?,

just thinking out loud
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Old Sep 25, 2014, 03:02 PM
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Very cool! I'm working on my design for the same thing. Just like yours, I referenced the rear thing for the mechanism. Aerocet and Wipline have publications and details online if you look enough. Ebay was a good resource as well for seeing the actual parts. I agree that this mechanism is the best option for a nose gear. My main worry is the torsional stress around the pivot point.

My design is a bit larger than yours (going on a 95" Cessna 182) so I've opted for air retracts. The main gear actuator is easy enough but the nose gear calls for something special as it requires a long stroke. I found a company, Bimba Manufacturing, who can produce an air cylinder in any length you desire down to the thousandth of an inch. Even better, they're dirt cheap! A 3.495" stroke cylinder costs about $30.

Good luck with your design, can't wait to see it come together.
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