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Old Mar 13, 2010, 03:13 PM
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Cox Micro Warbird spitfire on floats

I have started up a new kitbash of a COX/Gravity micro warbird. This time I will attempt to put the Supermarine Spitfire on floats.

I made a Rufe out of a Zero kit before. Although it was a good flyer, it never was much good as a float plane. The material of the float was to soft and the wingfloats didn't have enough buoyency. In other words, with a little wind it tipped over and it fried the electronics.

This time I'll start with ready made floats and using two floats I will have enough floatation and lateral balance. I have not yet decided how to proceed but I made a first setup to get inspiration.

Here are some preliminairy photo's.

Robert
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Old Mar 14, 2010, 07:23 AM
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Work on the tail

The rudder section of the plane is quite different from the original plane. Also the subfin is pretty important for a plane like this. I started work on the tail section today.

Robert
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Old Mar 14, 2010, 10:13 AM
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Hey Robert, looking good. One thing I would be careful about is the float pylons, even with the enlarged tail fin and subfin, those pylons you have right now have an awful lot of area in front of the CG. I was thinking if I ever do one of moving the pylons slightly back to help stability.

just a thought,
Angelo
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Old Mar 14, 2010, 02:07 PM
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Float pylons and canopy

Hi Angelo,

The current pylons are not scale or anything. They are there for the general idea of the plane. The final pylons are to be extended to after the CG like the 3-view shows. I dont think it will hurt the looks if I let them start a bit back from the leading edge of the wing. I need them to be pretty wide because I will use a carbon rod at the front and the back of the pylon as the support for the plane. If they are to close to each other it will probably not be strong enough.

I will connect the floats with carbon rods to prevent them moving apart and get wobbly on takeoff or landing. I might add a little carbon rod at the back of the floats to the fuse to give extra strength to the construction. I intend to keep the additional rods black so the will not be noticable there.

I take it from your remark that the presence of the vertical surface in front of the CG (the filling of the pylon) will cause problems in flight?

As for construction, I have made a plug for a clear canopy. I need to do a little more sanding to get it finished but it is looking pretty good already.

Robert
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Old Mar 16, 2010, 01:10 AM
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THe plug for the canopy is ready and a canopy has been pulled. The result is pretty OK.

Robert
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Old Mar 16, 2010, 07:25 PM
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Quote:
Originally Posted by Rotatorus View Post
I take it from your remark that the presence of the vertical surface in front of the CG (the filling of the pylon) will cause problems in flight?
That's what I was thinking. The enlarged fin and sub fin will definitely help, but those pylons are so flat, I would think the placement would be very critical, and putting them a little farther back, as you're suggesting, couldn't hurt.

With those pylons, she'll probably knife edge real good!
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Old Mar 19, 2010, 02:27 PM
outstanding in the left field!
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cool

I like the aircraft.

The super marine could do over 400 MPH which is awesome for a seaplane.

Thanks for posting,

Mike
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Old Mar 21, 2010, 05:29 AM
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Ailerons & floats

I got around doing some building last night. I installed ailerons and I did some work on the floats. The ailerons still need to be hinged with something else as maskingtape.

I am thinking about water rudder(s). They should be on the floats but I don't yet know how to make that work. I might go for an easy solution by extending the tailrudder into the water. I don't know how effective that will be... suggestions?

Robert
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Old Mar 21, 2010, 12:24 PM
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Hey Robert. What are you using for aileron likages? Is that shrink tubing? If so, aren't you worried about it wearing through and cracking with use? Just curious.
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Old Mar 21, 2010, 01:35 PM
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Hi Angelo,

It is shrink tubing. I have used it on all my aileron conversions and it has not failed me once. I use two sizes Shrink tubing over each other at the bent. This way if one gets punctured the other one takes over. I also make sure only to heat the bent just a little in order to keep that part flexible.

It works very well, it is light and durable.

Robert
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Old Mar 26, 2010, 11:39 AM
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Hiya!
I saw your post and expect that thing to fly REALLY great!
I modified a Micro cub with floats and the flying is better than stock!!
The floats almost make the plane seem like it has a gyro in it...
The weight of them keeps it flying level!
However, we did A LOT of R&D to get 'em to ROW!!
(More power, larger elevator, rough water)
The mounting ANGLE of these floats seem to be the most critical.
If you go super-scale looking they will be too low in front.
(As you rise off the water, if the last part touching is the nose of the float you flip it over!)
(You just can't seem to flare it enough to get the angle required when landing either)
(What's great, is the Cub just floats on it's wing-tops and you can just pick it out, shake it off, and fly it again!)

Keep us informed on your progress.
I'm really interested in more info!

Thanks
Brian-
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Old Mar 26, 2010, 11:46 AM
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Also,
The Cub taxis awesome!
I added rudder area, like the elevator, and as long as you get enough air going over it the plane has excellent directional ability in the water.
So no we added no water rudder... Didn't need it!

Brian-
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Old Mar 26, 2010, 04:56 PM
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Hi Brian,

Thanks for the input. I will let you all know what I've been up to and what the results are. This week has been very busy at work and the weekend will not allow me to do any building I expect. When something gets done it will be posted here.

At what angle would you mount the floats in comparisson to the wing? What is the distance your step sticks out aft of the CG? How wide is your wing (not wingspan)? I would like to get an idea of your cub's configuration.

I have replaced the brushed motor with a brushless one (2000 RPM) and I hope it will do the job. I have had quite good results in the past so I expect it to be enough to ROW. The floats will be made smooth and covered with liquid sheeting (see WOW-planes) to get a plastic like smooth surface of the floats and pylons. It will add weight but I think it necesairy to get a real smooth float surface to pick up speed and get on step. The smooth surface could be waxed for some water repellant effect and to reduce surface suction.

So far just ideas which need to put to practise to see if it will work.

Robert
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Old Apr 05, 2010, 05:11 AM
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pylons

Hi all,

I have figured out how I will do the pylons on this bird. It will be a thin piece of plywood and two carbon fiber sticks. One at the front and one at the back. Then I will use thin plywood where the carbonfiber sticks will meet the wing to prevent them to damage the wing when force is applied. At the outside (under the wing) two pieces of balsawood will keep the pylons in position. I hope this will be study enough.

Pylons may be dressed in 3 mm depron to shape the pylons in a more scale way. Current weight with all items to complete the bird and a 3 cell lipo 350 mAh is 142 g. Add some for glue and paint, this warbird will be no more heavy as the other warbirds I have build and flown.
My set target weight will be under 180 g ready to fly. I hope I can manage that.

Robert
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Old May 12, 2010, 12:42 AM
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update

The plane is finished, floattrials have been done, it has tipped over, crashed, repaired and further reinforced...

I have posted pictures in the Gravity thread like here:
http://www.rcgroups.com/forums/showt...133454&page=46

The video of the floattrials:

spitfire floatplane floattrials final (4 min 28 sec)


I will add flight video when flow, filmed and ready.

Robert
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