|Oct 26, 2012, 01:57 PM|
Joined Oct 2012
I'm reading this thread for the first time today. Love what you're doing with this Zero. I've been trying to write a story about Rufes duelling with a Catalina in WWII. Consequently, I was delighted to come across this thread.
|Oct 26, 2012, 02:26 PM|
As for your floats, perhaps a sliding rail system secured by magnets. On the top of the float brace, an "I" beam. On the wing a "C" beam and the float slides in front to back and rests against a stop at the rear, all secured by a shear mounted magnet... I've had great success so far with varied magnet and pin arrangements.
Here's a bit of inspiration to keep you rolling, pics of the George...
Again, I'm watching this with great enthusiasm.
|Oct 26, 2012, 07:16 PM|
I took the day off. Nominally, I prepared for the approach of Hurricane Sandy. I had much to do in the Garage!
I decided to permanently fasten the tip floats to the wing as she's getting a bit portly. AUW, ready to fly, with battery (3S 800mAh) is 520 g!
I'm glad I didn't reduce the wing area to closer to scale and I hope the floats hold her up. She's too big for the bathtub.
Motor is a Grayson Hobbies 2208-14, 1450 kV, rated at 12 A (60 sec surge).
ESC is 18A.
prop is 7x5 2-bladed.
The combination at WOT pulls 12.1 A generating 135 W.
If she'll float, she will fly!
I need to move the motor about .5 cm to get the prop centered better in the cowl; and, I'm going to paint the firewall and oil cooler duct black.
Then, I think its time for some panel lines, weathering and some marking.
|Oct 26, 2012, 10:27 PM|
About adding a shaped tail to the GWS float that would taper it to the scale point. It would also add some more buoyancy, aft.
If she sits tail down, in the water, after setting the CG, I will add a layer of foam to the bottom of the main float afterbody. The step is so high that I think it would not matter.
|Oct 27, 2012, 09:23 PM|
Made a trip to the lake, today.
Did some taxi tests... here's what I learned.
1. I was a bit tail heavy; about 1.5 cm, as I thought... I've already made modifications enlarging the battery tray/tunnel forward, allowing me to move the battery almost to the fire wall. I have to attach a piece of nylon line to the battery so I can pull it out of the tunnel.
2. The asymmetric modifications to the tip floats work very, very well... too well. When a float would be in the water, it would actually turn away from the float. I've decided to remove some of the tip floats' keelson and semi-flatten the bottoms. This will also help the wing stay on top the surface.
3. I do need a water rudder. There was a bit of breeze blowing on to the land and the air rudder did not give enough directional control. I am going to extend the transom of the GWS float to a point, giving me more displacement aft of the CG and a sternpost upon which to hang a water rudder. Now for running it. I'm thinking of putting a ultra micro servo in the added section of the float and running three small enameled wires to the upper surface of the wing, when I would plug it into a rudder servo "Y". I could paint the wires into place.
4. I'm going to change the prop from one with less pitch and enough diameter to keep the motor/ESC loading balanced and high. I want more of a "climb prop" to get the aircraft up "on step" quicker.
5. I have to learn to resist using elevator to get the plane on step. The plane broke surface and I had a "Spruce Goose" moment. Unfortunately the up elevator I'd been applying caused an appalling snap loop about 2 feet off the water. Cutting the throttle and yanking the ailerons over Immleman'd the plane level as it stalled and the plane "plopped" into the water, about 20 degree nose down. The engine dunked and there were a few drops of water in the cabin but, no foul. It was quite dramatic.
A friend was taking photos and as soon as I get them, I'll post.
I'm actually very gratified by the testing.
|Oct 27, 2012, 10:08 PM|
Pictures from today.
|Nov 01, 2012, 08:00 PM|
I had gone overboard to avoid pinwheeling into the down float by putting scale toe-in (2.5 degrees) and curving the keel of the tip float. The combination proved too much and the plane actually turned away from the down float.
I've shaved off some keel from the tip floats.
I've also moved the battery forward to put the CG where she should be, and am adding some length to the main float, tapering it to a point (as scale) and now I'm configuring a water rudder. I'm also (Main float mod phase 2) going to move the step back about an inch and square it off, per scale.
Once this is done and better weather comes, I plan to water taxi test again. I'm also going to up the motor size and go to a climb prop, including some three blade prop testing.
If that doesn't cut it, I believe I will try aaronredbaron's suggestion of stepping the tip float. It shouldn't take much.
|Nov 02, 2012, 09:11 PM|
I carried out Phase 2 on the main float modification.
-- I added a single layer of MPF to the after section of the float; added 1.5 inches to the forward body at the step; and, squared off the step.
I moved the battery as far forward as possible, performing some internal surgery to assist.
-- I cut out the battery shelf in the cockpit; added a shelf below it; and, carved the internal battery area until I could push the 800 mAh 3S almost to the firewall.
She now balances on the step!
I also cut an air conduit from the battery shelf inlet down into the avionics bay.
I made a rough drawing of the internal changes.
|Nov 06, 2012, 03:29 PM|
I was able to hang the water rudder. I made it by sandwiching a piece of 1.5 mm Styrene between two 3 mm pieces of foam. I used two left over hinges from the GWS kit to mount it.
I used lightweight spackle on the bottom of the float and will sand it down tonight. If I finish the sanding, I'll also add a control horn to the water rudder and, depending on the time of even, will paint the float.
I've also started scribing the panel lines in the aft fuselage.
I may be ready for second taxi test by the weekend.
|Nov 08, 2012, 03:03 PM|
Hi David! She's looking marvellous!
Alas, between real life, the rubbish weather and the fact that my "paint shed" consists of standing out on my 3rd storey balcony and hoping that the wind is such that not too much paint winds up on me, I haven't made a heck of a lot of progress.
I too had originally pondered a water rudder which is why in my first iteration of this project I was working towards a built-up float with a servo buried inside it and the servo cable running up inside the center pylon. If I find I still need to go this route, I'll just dig out a small pocket in the foam, plunk the servo in that and away we go.
I really haven't done or even thought about deviating from scale to make things easier, to me the point of doing a scale subject is learning and mastering the peculiarities of it but again, nothing a little retro-engineering can't fix.
Having flown my old GWS Zero in the landplane configuration I made sure this time to hollow out the battery compartment up to the firewall before joining the fuse halves so I should be good in that respect.
I'm really glad to see how well your project is going! It's very much an inspiration for mine
Keep up the great work!
|Nov 08, 2012, 03:33 PM|
Thanks for the encouragement. In my first taxi tests, I had almost no directional control in the water.
I'm in an apartment, too. I rent a garage on the first floor. But, more to the point, I also sculpt and occasionally use power tools, generating a lot of dust. I created a "glove box" from a large, translucent tote. I turned it upside down and cut its bottom off at a diagonal. I bought a piece of plexiglass, a couple of hinges and weather stripping and made a hinged top. I cut two holes using a coffee can as template. I put my tools and piece in the box, close the lid, put long gloves on, wrap a dish towel around each wrist and stick my hands into the box to work.
Later, I added a fitting to attach the hose from my shop vac and use a small broom to move the dust towards the vacuum.
it was a simplified version of the design here
Perhaps something similar would help contain the paint overspray.
|Nov 08, 2012, 04:22 PM|
Bless your heart David!
Alas, such a box would eat up valuable hangar space! My place is like yours, but minus the garage. Besides, it's not a biggie to vacuum up wood and aluminum shavings when you're going after the cat hair!
Also, my birds seem to be getting bigger these days, my 48" Windrider Hurricane case in point, so spray painting must remain an outdoor activity. I often tape black garbage bags to the deck and along the railing to keep things in check, but even so weather is still a factor.
Did you leave your tip floats bare foam? Or did you glass them? I glassed the fuse and wings on my Rufe but it was such a pain in the butt and I want to make sure the bottom of the tip floats are nice and smooth, so I may just surface the bottom of them with silkspan and Z-poxy... I sealed the gap between the plastic bottom of the main float and the foam with clear silicone. Hopefully the paint won't dislike this too much.
Anyhoo, I'll try and post a very meager few pics in my thread when I get home to prove that I am not dead
|Nov 08, 2012, 07:40 PM|
Ready for 2nd series of water handling tests
I throw a painter's canvas on the floor under the table, to catch the shakings.
I build a box for each of my birds, so I can put them on a shelf without worry. They can be almost as fun to build as the plane. I unfolded the box that came with my PZ Champ Ultra Micro and created a spreadsheet that tells me all the various dimensions, given a specified interior volume. Then, I made friends with the manager of a nearby mattress store, who lets me know when he has boxes he can give me.
I haven't glassed a thing. Some lightweight spackling and paint. I may put a coat of clear WBPU but I'm at 540 grams ready to fly.
I've learned from my Polaris seaplane that when properly balanced, just ahead of the step, these planes can get up on step and into the air pretty quick... no more than 3 or 4 plane lengths. I switched to a climb prop; more diameter and less pitch that pulls about the same wattage. The top speed will be less, but the efficiency at low speed should be better; like flying in 2nd gear instead of 3rd.
|Nov 11, 2012, 12:00 AM|
2nd Taxi Tests
I had some great tests, today.
I did a really good job improving the buoyancy of the after section of the main float; so much so that the water rudder was 80% out of the water!
I think that, rather than remove material from the float and repainting, I will extend the water rudder a bit deeper.
Also, I have some asymmetry in the rudder and elevator movements. I realize I set the servo horns at a right angle to the centerline, rather than normal to the control rods. I'll be fixing that and will post a photo.
She taxied very well... and I had a Howard Hughes moment when she lifted off and I learned of the elevator asymmetry as she went for a another dunking; this time ending up inverted in the water. She floats well!
I'm preparing some videos... here is the first.
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