MAGNESIUM SUMP
Howdy folks. Been a while since I posted. Had some other things in life I needed to tend to. I have not really had a chance to fly the Cub all that much. Gave a few rides to the neighbors and that is about all. But I'm back at it so thought I'd bring you up to speed a bit.
GRT - After we got home from Oshkosh the GRT was working fine but Buck and I re-crimped a new pin on the power wire to the GRT and it has been fine ever since. It was working before we did that, so again, I am not entirely sure that was the fix, BUT it has worked every time since with no problems.
ECI makes a magnesium sump for the 0-320 and 0-360. I managed to get one thanks to some help from Airframes Alaska. Its a long story. Airframes does not sell these sumps, you will need to talk to ECI. Outright they run about 1000 bucks, but if you get it as part of your engine kit I think the additional cost is around 500 dollars. It saves right at 7 pounds. The sump I took off my engine weighed 14.55 pounds. The magnesium sump weighed exactly 7.55 pounds for a savings of
Exactly seven pounds. I am still in the process of swapping the sumps out but taking seven pounds right off the nose with something like this is great. It is not like we have gone to a radical battery that you are not sure of, or electronic ignition that some folks are not comfortable with, or things like aluminum cylinders. This is a sump. It is not structural, it does not rotate, store energy, etc. This is a no risk weight savings. Pretty darn cool.
FOLKS - Make sure your carb and intake locations match the Magnesium sump locations. There are a lot of different sump configurations. They will all bolt to the case but if you are retrofitting this new sump, and it does not match up, you could find yourself building a whole new cowling.
The old sump coming off.
The old sump in red and the magnesium sump in gray.
The new sump going on. I was at 1059 empty weight. Theoretically this would bring me to 1052 empty weight. I am going to try to do another full weight when I go to floats so it will be interesting to see what has changed.
FLOATS
I have a set of Wipline 2100A amphibious floats. I am working on the install now. One of the things I had to do first was make a spreader bar for the hoist and also get a hoist. Here is what I did and what I learned.
I purchased a 3/16 thick by 2" square 3 foot long steel tube from the local steel supply company. 14 Bucks. I purchased a Gibralter Shoulder eyebolt # 73108219 from McMaster-Carr (MSC Supply). This is for the center of the lift bar that the hoist attaches to. This eyebolt is rated at 5000 pounds with a safety factor of 5X. Then I purchased two eyebolts # 73108144 for the ends. These attach to the lift rings on the Cub Via 1/2" quick links part # 67785606.
I also got two eyebolts for the Cub # 73108144 rated at 1400 pounds each, again with a 5X safety factor.
I did a little homework on the net and I don't think you want to get a Harbor Freight Hoist. I went to a company called CM and as best as I can tell they make a good hoist (actually they have several lines/grades), and I got the Hurricane (Line/series) Hoist. Cost about 320 bucks. Then I had to make sure the rafters in the hangar would support all this so I had a civil engineer look at my hangar truss system and run some stress analysis to make sure I was not going to pull the hangar down when I lift the Cub. Then I mounted a 4X6 beam in the rafters, per the engineers recommendation, to attach the hoist to. Whew. Takes a lot of work to mount the floats, and I haven't even done anything yet.
This is all the stuff that normally goes in the Cub for the Amphib floats. Weight around 17 pounds. Electric motor drives a hydraulic pump with a reservoir, lots of limit switches, relays, check valves, pressure relief valves, and a manual back up pump system. It also includes a gear indication system with lots of micro switches and also a gear warning system as well. It is quite sophisticated and works well. But it is pretty complicated.
I tend to go for the light and simple.
So I am going to have a manual pump, valve and reservoir. And thats all. There will be no back up. If it fails (there is not much to fail) then I will have to land accordingly. If the gear fails down I will have to land on land. If it fails up I will land in water, or perhaps grass on the float bottoms. I don't see this as a big deal. Also, I can't envision a situation where I would want to raise and lower the gear more than once per flight. I don't see myself doing a touch and go on the water, then one on land, then back to the water, then back to land etc. You take off, raise the gear, go play in the water, come back, put the gear down and land. So I will manually pump the gear up and down, probably once per flight.
The back up (manual) pump that comes with the Wip float system takes about 100 strokes to raise or lower the gear. That is too many for a primary system. Fine as a back up but not for every flight.
I purchased a Parker 914 series pump. This pump is a little larger than the Wip unit and it takes 25 pumps to extend the gear and 22 to raise it.
My pump will be mounted under the front seat something like this. I will post more detail as I work this out, and weld it up, in the next day or two.
The floats basically have two hyd lines per float. One line pushes fluid behind the piston to push the piston out and extend the gear. The other line is on the front side of the piston and as the piston goes out (extends) the fluid on the front side of the piston is pushed out of the way and back into the reservoir. To raise the gear we reverse the flow of the fluid so that the fluid goes under pressure to the front side of the piston and pushes it back. This then forces the fluid behind the piston back in to the reservoir. The pump has two openings. One supplies fluid to the pump. The other is the high pressure fluid going out. The pump is a double action, meaning that it pumps out when the handle is going down and when the handle is going up. So basically we take fluid from the reservoir and push the piston, when we do so fluid is flowing back into the reservoir at the same rate it is going out.
This was my test set up. Pump, valve, and the gallon of hyd fluid acting as the reservoir. I measured the fluid going back into the reservoir and what I got was 16 oz goes into the reservoir when extending the gear (this would be the fluid that was in front of the piston)and takes 25 strokes. It dumps 19 oz into the reservoir when retracting the floats and takes 22 strokes. This means the pump is putting out about .75 oz per stroke.
I have ordered a Parker 910 series pump which should be very similar to the one above (914series) but it is supposed to put out 1 oz per stroke so this should reduce the strokes required to about 19 and 17 respectively. I think. I'll let you know.
There is absolutely no doubt when the gear is fully extended or retracted. The pump handle just instantly locks up. You can't move it either up or down. Hydraulic lock because there is fluid on both sides of the piston. Because of this you don't need a pressure gage. You could only over pressurize it if you intentionally massively FORCED it. For the same reason you don't need a relief valve. It operates at about 500 PSI but the lines, pump etc are rated at 1700 to 3000 PSI. So again you will never get there unless you force the pump. The handle takes about 15 pounds max force to move the gear and I'll bet it would take well over a hundred to move it after you hit the stop.
This is the valve I'm using Whitey 40 Series 1/8"FNPT 1 piece 4 way ball valve SS-43YF2.
This is what the plumbing looks like. The pressure goes into the valve from the pump. It is a two position valve. In one direction it pumps the gear down and allows the return fluid to go into the reservoir and in the other direction it retracts the gear and again allows the return fluid to go into the reservoir.
Hope all this makes a little sense. I'll keep posting more info as I go. I think this system is going to work well - light, reliable, and simple.
Hope this helps
Bill