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Reinstalling Our EDO 2425 Floats
We put about 20 hrs of wheel flying on our Stinson before we were overcome with the urge to reinstall our EDO 2425 floats. The camping season was well upon us and I wanted to finally see for myself what kind of performance we would have when loaded with the family and gear. The hydraulic hoist we used to lift the aircraft when we started the project was inadequate, or at best marginal, to lift the fully assembled aircraft. We decided to resurrect our old reliable 4x4 A-frame for the job. Installing the floats is a two-man job. My wife Storm and I had the floats installed in about 6 hours. We spent the next day building new cables for the water rudders. If you don't have to build new cables and you start early enough, you could complete the job in one day.
I used a 2-ton come-along and heavy chain secured to the engine mount to support the bulk of the load.
Before taking up the slack in the hoist you have to lift the tail a good 6 feet. Once you start lifting the wheels off the ground you'll be transferring around 200 lbs onto the tail so use an adequate support.
Removing the rudder will allow you to use a heavy ladder to support the tail. We secured the tail with ropes in the event the winds picked up.
You'll have to remove the front seats and under seat floors to gain access to the landing gear hinge pins. Hoist the wheels off the ground and remove the lower bolt securing the shock struts. Now you can remove the landing gear hinge pin and carefully remove the gear leg assemblies.
With the struts removed from one side of the floats, carefully slide the floats into position. Ensure that the remaining struts are secured snugly to the floats to prevent them inadvertently falling against the fuselage! It's happened to me and it creates a beautiful hole in fabric.
Lift the aircraft high enough to secure the diagonal and rear struts. Keep all ball joints and pull blocks snug but free enough to move.
Continue hoisting the aircraft until the front struts can be secured. Snug up all the strut mounting hardware but not so tight as to prevent movement. Install your brace wires and square your installation. A good place to check your level is to measure the distance from the front strut up to the bottom of the wheel gear mounting holes. Once your wire braces are tightened and locked you can tighten and lock-wire your strut hardware.
Install your water rudders and you're off to the races.
You're going to have to manufacture your own water rudder arm. Here's my solution and some pictures of others around our airport.
You'll have to make the new arm long enough to achieve full water rudder deflection.
My setup consists of a welded steel insert which is secured to the rudder and an alum. arm which is riveted to the insert. This setup has withstood many years use.
This is how most of the Cub owners have chosen to construct their rudder arm. This type of setup would mean you wouldn't have to remove your original arm when changing over to floats. I don't believe this is an option for the cast arm used on the Stinson 108's.
There's a down side to extending the rudder arm. This is a picture of another Stinson seaplane (not mine). The additional torque required to move the water rudders will cause a strong twisting force on the rudder resulting in cracks in this area of your rudder. A doubler must be installed in this area to reduce cracking - see pictures or my rudder above.
I can't tell you how impressed we are with our Stinson - now that we've installed the 210 hp Continental. On my solo test flight, I was off the water in 9 seconds... access the WMP (Windows Media Player) format video through our menu bar link "Stinson Video Clips." After takeoff, it's no longer necessary to retract flaps or accelerate to 80 mph to start your climb out. I will say that the aircraft is a little more nose heavy then with the Franklin. Not surprising with the constant speed prop. Solo and lightly loaded the aircraft is at the forward c of g limit. This isn't too bad considering the battery is still installed under the pilot's seat and I didn't have to install any ballast on the tail post! The effect of this forward c of g is not that significant. On wheels I noticed that the applying heavy brakes could lift the tail off the ground - even with full up elevator... this is something I never experienced with the Franklin and Goodyear wheels and brakes. On floats I noticed the bow of the floats ride a little lower in the water - they come up immediately with the application of takeoff power but, I pickup a bit more spray when taxiing on rough water. On final approach, one requires a little more nose-up trim. At idle power settings - you might even need full up trim... not the norm, as you drop like a rock. There is no tendency to pitch forward on touchdown. All in all it's a damn-fine float plane!
Flights with the family aboard (520 lbs.) are of no concern regardless of the conditions. Hot, calm weather - no problem. We've operated the plane for over a year now on floats and have made trips from lakes at density altitudes of over 4000 feet. Gross weight take-offs, even at this altitude, were not a problem. Fuel consumption at cruise is around 7.5 to 8 gph v/s 10 gph with the Franklin. Oil and cylinder head temperatures are low. In fact I'm thinking of installing a cooler baffle for cooler days. HP Speed Floats IO-360 rpm/mp / Pwr / fuel flow Franklin 165 Pwr 157 hp 115 mph 25/25 75% 11.5 gph (us) 95% 138 hp 110 mph 24/24 65% 10 gph 85% 111 hp
102 mph 23/23 53%
8 gph
66% Dave Miller
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