Mead 1430 Amphibs on 11-EX

Dan Gervae · May 21, 2022

I’ll keep a good eye on it..it has a hatch you can open and check before each flight and after. These marine trim motors/pumps live in bilge/engine compartments on boats pretty well… but you are correct…I must be diligent about it…I do like that when changing over it’s only the brake lines and wire harness to unhook. The floats have all hydraulics self contained. If I don’t like it after some time I could convert to a hand pump inside the cockpit.

TurboBeaver · May 22, 2022

Dan,
Did you ever get them mounted on your plane?
E

Dan Gervae · May 22, 2022

I just got the streamlined tubing to do so…I ordered some weeks ago but have not seen it yet. A friend had some so now I can proceed. Right now we are machining all of the end fittings for the tubing and the main gear attach blocks. I’ll hang the plane this week and get to fitting and cutting.

Dan Gervae · May 22, 2022

I know this plan will add 5 or 6 lbs to my setup, but I’m going to power the pump motor with a lightweight deep cycle 12v battery separate from my main electrical. The cycle time for this gear system is 20-25 seconds as the wheels go down and come up one at a time based on distance from the pump. I will put a throw over switch to my main 12v bus as a backup. Thinking something like the attached: I will test how many gear cycles it will take before going dead. I have a small wind generator and a solar panel for charging.

skywagon8a · May 22, 2022

Dan Gervae said:
I just got the streamlined tubing to do so…I ordered some weeks ago but have not seen it yet. A friend had some so now I can proceed. Right now we are machining all of the end fittings for the tubing and the main gear attach blocks. I’ll hang the plane this week and get to fitting and cutting.

I made my fittings from wood initially, since I expected there may be some changes. Then once I was certain everything was as I wanted it, they were made just once from aluminum. Changes were made. You will be surprised how little differences show up when you think you have it correct the first time. Just a couple of degrees angular difference in a fitting can cause you to tear your hair out.

skywagon8a · May 22, 2022

Dan Gervae said:
I will test how many gear cycles it will take before going dead. I have a small wind generator and a solar panel for charging.

When the gear approaches the end of it's travel the electrical loads go way up. With a battery only powering the gear, you may find insufficient power available without having a generator in the loop. Then sometimes when there is insufficient electrical power, it is possible to do some damage to the electrical components. Wirewenie can speak to this better than I. Sort of like driving up hill with a load without downshifting.

Dan Gervae · May 22, 2022

skywagon8a said:
I made my fittings from wood initially, since I expected there may be some changes. Then once I was certain everything was as I wanted it, they were made just once from aluminum. Changes were made. You will be surprised how little differences show up when you think you have it correct the first time. Just a couple of degrees angular difference in a fitting can cause you to tear your hair out.

Thats the plan, use the table saw, band saw, and jigsaw to mock up the fittings and then when satisfied..machine them from 6061

Dan Gervae · May 22, 2022

Noted. I’ve cycled the gear about 50 times with a battery I have in my hangar that I haven’t charged in 2 yrs…my little 8amp B&C probably would be insufficient so I’m going to charge the amphib battery with my 14A wind generator (I think)

Dan Gervae · May 26, 2022

mocking up fittings
out of trex. All dangled and cutting struts

skywagon8a · May 27, 2022

Just a small tip. Retract the landing gear so the floats are resting on their keels. Then line up everything. You will find it takes very little to move something changing your dimensions, climbing around, over and bumping into. So if the wheels are retracted that will be one less thing which could move. Moving the floats just a tiny bit can change dimensions and angles a lot without you being aware. The plane dangling from a hoist is enough wiggly. You need the floats rock solid on the floor. At least I do.

Looks good sitting above the floats. You must be getting very excited!

Dan Gervae · Jun 1, 2022

I smashed the ends of some EMT conduit to mock up rigging....punched holes and installed, now I have 2 pieces that need to be machined (front fuselage fittings) which we made of trex plastic as a mock up. getting there....More time into this than I expected. Step positioned at 22" aft of Leading edge, wing 4.5 degrees to floats (bottom of wing). Progress. Now I can cut my streamlined tubing and drill those....fit....then remove and paint.

skywagon8a · Jun 1, 2022

Dan Gervae said:
View attachment 61278

The load path of a strut should be a straight line between the center of the fuselage fitting to the center of the float deck fitting. The load path on your front fitting is passing above the center of the fitting. This is placing a twisting load on your deck fitting rather than a straight line path. The center of the fitting is the center of float fitting where the horizontal bolt holds the fitting to the float.

The bolt which attaches the strut to your new fitting should be an inch or more aft of it's current location. It's hard to tell the exact dimension when looking at the picture. It could be aft and down a bit.

This is true whenever designing structural load paths.

Dan Gervae · Jun 1, 2022

Front spreader bar is farther forward than my Baumanns by a lot making front strut long and at a shallow angle.

Dan Gervae · Jun 2, 2022

The offset front fitting should align the forces....(i'm an Electrical Engineer not Mechanical) but it looks OK....we had to make this fitting...but it's an exact copy of the Mead factory fitting...I was just missing one. Then the flying wires should help equalize the forces I assume?

skywagon8a · Jun 2, 2022

This is what I'm talking about. The dowel represents the load path.

.

Your diagonal is close. I would move the bolt hole a little bit aft.

The person who designed your Mead fitting needs to go back to engineering school.

The struts carry compression loads, the flying wires are under tension.

skywagon8a · Jun 2, 2022

Compare the load paths of these two installations. The first one exerts all bending loads on the fittings and bolts except for the one bolt which attaches the strut to the fitting. You can almost picture the first one tearing off in a bending motion.
The second picture shows all attach locations are loaded in shear. The loads are directed into the float deck where that final fitting is loaded in shear..
Strength is in shear. Bending is like wet spaghetti with no support.

. .

Dan Gervae · Jun 2, 2022

I see what you mean…here is a factory install of Meads on a CubCrafters Sport Cub…same thing. There are (4) AN5-33A bolts holding the deck plate through the spreader sandwiched by carbon fiber block. Maybe they tried to account for it some that way….still, what you say applies. Rear 2 deck bolts being forced in tension, front being pushed basically trying to tear deck plate out…but I wonder what the maximum force is as designed…I’ll never know since Phil Mead is dead.

Dan Gervae · Jun 11, 2022

struts are made…on to wire pulls. Boy, I have double the hours I thought I would into this. Lol. Plane is all plumb, step is 22” aft of leading edge, 4.25 degrees of incidence between bottom of wing and floats. I should finish before summer ends. Ha Ha….I’ll be at New Holstein for sure…I should have plenty of time for flight testing and tweaks ahead of that.

skywagon8a · Jun 11, 2022

Keep close tabs on that rear float deck fitting. The load paths for the two struts are nowhere near aligned correctly. I would never allow something like that to be pushed out the hangar door. I though I made that clear to you in post #75 & #76.

It may not fail due to the massive size of the fitting, no guarantees.

Look at this one.

View attachment 61405 If you wish I'll try to get a closer picture.

skywagon8a · Jun 11, 2022

This is a better picture.

You can fix yours by making a new deck fitting. The struts will not need any changes.

Dan Gervae · Jun 12, 2022

The only thing that makes me feel like this, although not a perfect design…is the fact that not only is there a very robust deck plate with 4 bolts going through an impressive structure….also the wire pull attaches to the AN6 bolt and the flying wire attaches there and back up to the fuselage fitting on the other side which will carry a lot of that load path…it’s the same on the rear fittings. Aerocet actually has a similar fitting, only the wire is attached to the 2 bolt deck plate. here are some photos.

mead wire pull

Aerocet 1500 floats design

skywagon8a · Jun 12, 2022

Look again at your rear float deck fitting and the alignment of the load paths with the deck fitting. Remember all of the landing loads are compression in nature through the struts in a straight path between their attachment bolts continuing straight through the bolt location. The junction of those multiple extended paths should all come together in the same location. Due to the vertical down force on every landing, the geometry of the front and diagonal strut will be attempting to expand the base of that triangle. The diagonal strut will be pushing the top of deck fitting aft. The rear strut will be pushing down behind the deck fitting. These two forces coupled together will be trying to roll/twist/peel the deck fitting aft. The resultant loads will be trying to break the deck fitting at it's forward side where the thin flange extends forward being held to the float deck with the two bolts. The rear side of that fitting will be trying to bend aft. IF you were to change the fitting which connects the two struts to the float deck fitting so that the two strut load paths are directed at the center of the float deck fitting, those destructive loads will be eliminated.

The cross wires are in tension and their only purpose is to maintain the alignment of the floats to the fuselage.

Dan Gervae said:
View attachment 61403.

Dan Gervae · Jun 12, 2022

Baumann did the same thing. They got the front fitting right though.

skywagon8a · Jun 12, 2022

I see why you did it the way you did. Why Meade and Baumann both did it contrary to proper engineering practices, I can not say. They both should have known better.

Dan Gervae · Jun 13, 2022

closer by the day

Dan Gervae · Jun 13, 2022

Now I need to wire controls…fabricate rudder retract cables, do weight and balance etc.

Dan Gervae · Jul 15, 2022

taxi tests show I need more nitrogen in front shocks ….it’s a bit of a pain to do too. After a setback with a major infection in my foot I finally got this done. Will report flight tests as weekend goes on

Dan Gervae · Jul 15, 2022

this just happened…almost taxied into a hanger….bummer. These were new stock Scott masters .I don’t feel too great about the other one now either. Not good. I was stepping pretty hard to turn on the amphibs, but this could have been trouble on a landing possibly

Gordon Misch · Jul 15, 2022

Ugh! Maybe look into Grove masters, the form factor is the same and very well built. Dunno how compatible they'd be with your wheel cylinders in terms of fluid displacement, but I bet Robbie Grove would.

skywagon8a · Jul 16, 2022

That brake failure is a bummer. It's good that it happened when it did and not when you really needed the brakes, as scary as it was. Was that an actual Scott master cylinder or a Chinese pot metal copy? I know it's a lot of work, but you could make one. I made one out of solid aluminum.

Amphibs do require a lot of dependable braking capabilities. The smaller the wheels, the greater the pressures required since the small diameter disk has less mechanical advantage. You have 5" wheels which are the worse. I suggest you add another brake disk to the other side of the wheel along with the appropriate wheel braking unit. Plumb the two sides together with a "T" in the brake line. I did this to a set of EDO amphibs which had 5" wheels. It made all the difference. Raisedbywolves has these floats now.

Also your nose strut needing air could contribute to the steering issues as the angle of the pivot can make turning difficult. It wants to keep going straight.

Mead 1430 Amphibs on 11-EX

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