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Old Jan 06, 2008, 04:29 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
Hi Robert,

Current plans are to put the battery in the wing. Once the nacelles are built I will have a better idea. The only thing planned for the fuselage is the rudder and elevator servos. The nose will be sealed once the servos are operational.

Len
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Old Jan 06, 2008, 06:23 PM
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DUNDAS CANADA
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Len, if I was you I would not put the batteries high above the C/G. The side sponsons might not be able to support the weight of the motors and the batteries. More likely, the model will tip over to one or other side when placed on the water surface.
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Old Jan 06, 2008, 06:37 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
LADDIE - Good point!

The motors will weigh 15 grams, the receiver and two servos for the ailerons and a motor controller around 25 grams. The battery is 45 grams. My first choice is to put all that up in the wing, but that and the wing is probably half to two thirds of the total weight.

Len

edit: If two of the new A123 1100 mah cells are used it will double the battery weight, but they could be sealed in the fuselage. It may require weight in the nose just to get it to ballance, better battery than lead. The power wires need to be routed, probably up the front wing brace. Maybe provisions should be made to switch to the 10 gram motors and the GWS three blade 5x3, just in case it continues porking up.
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Old Jan 07, 2008, 04:20 AM
Registerd Beaver
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Australia, WA, Warwick
Joined Jul 2003
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Len,
You've probably already looked into it, but I used winding wire for circuit wiring before.
You don't need all that PVC insulation which adds precious weight. this web site is an Aussie one but it shows the stuff I'm on about.

http://www.dse.com.au/cgi-bin/dse.st...uct/View/W3122

Phil
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Old Jan 07, 2008, 08:43 AM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
Phil,

Even though I wind my own motors and have a lot of the wire about, the thought of using it to route power in a plane had never crossed my mind.

Some 22 guage should more than handle the current.

Thanks!

Len
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Old Jan 11, 2008, 08:35 AM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
There is no real progress to report. There have been reports of running two of the ten gram motors with one of the 6 amp HobbyWing Pentium ESC, so naturally an attempt to run three of the 5 gram motors had to be made. Two would not run at the same time at the same speed. One would run normally and the other would run at what looked to be half speed. It was not the same one that would run normally each time. Sometimes one would not start at all. This just won't cut it, especially with a waterplane.

My current thoughts are to run the two outboard motors with their own Pentium 6 and use a Pentium 12 for the center motor. The BEC from the center motor ESC will power the radio and servos. The Pentium 6 only has a .8 amp BEC and the Pentium 12 is a 1.5 amp BEC. The power line will be cut coming back from both of the Pentium 6 ESC.

One of the motors caught a winding on a magnet and self destructed. The windings are not glued down and are easy to remove, but winding it again will be quite a trick. Fortunately I have four of the 5 gram motors and so there was a spare. The windings were counted as they were removed and they varied between 14 and 17 with the predominate count being 16. Two strands of something mighty fine were used. Using #30 wire I can get maybe ten windings all around, and even that will be a trick. I used my $3 Harbour Freight maginifier visor and my wife commented - "There are nerds, and there are super nerds and you just made super nerd."

One of the water wings is not perfectly horizontal and I am seriously thinking of redoing it. The carbon will be ok, but the ribs and skin will have to be replaced to get it right. Maybe it will be left for later. If everything else goes together and it flys, then maybe I will worry about improvement.

I want to get those three motors running then I'll feel like progress is being made again.

Len
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Old Jan 12, 2008, 03:44 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
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Each of the motors is running with it's own ESC. The cowls have been started and the center nacelle is roughly shaped. The piece under the cowl flaps has not been glued yet.

While looking for a source for the new 1100 mah A123 cells (plans are to use two sealed in the fuselage) I discovered that I could purchase a Black and Decker VPX 7 volt Lithium-Ion battery for $18.95 including sales tax from WalMart and by specifying "ship to store" it will be shipped to a store near me that I specify and they will email me when it arrives. I don't have to pay any shipping this way. What a deal. I figure it will last longer than the plane (people have run over 500 charge discharge cycles on A123 cells with little degrading). My plans are to bring out a wire connected between the batteries and that way I can charge each individually. I believe they weigh about 45 grams each.

http://www.elektromodely.sk/A123/APR18650M1_2007-05.pdf

Len
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Old Jan 12, 2008, 06:50 PM
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's-Hertogenbosch, The Netherlands
Joined Apr 2006
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Hi Len,

How are you going to attach the nacelles to the plane? Do you cut out a piece of the wing or do you cut a pice out of the nacelle and slide it over the wing?

Robert
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Old Jan 12, 2008, 07:58 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
Hi Robert,

My thoughts have been on that very subject. The bottom of the wing is covered. It might be easier to put on the nacelle afixing it to the forward carbon spar, install the electronics, put in some support around the nacelles and then cover the top of the wing.

The other approach would be to install the electronics, cover the top of the wing, slot and attach the nacelles while routing the motors and ESC.

The first approach would be easiest because of the wiring harness needed from the three ESC to the battery connector and to the receiver. That could be installed and the motors installed after the nacelles are installed but before the wing is covered.

An access hatch will be needed to get to the plug for connecting and charging the battery which will be on the wing or perhaps the side of a nacelle.

Very little of the center nacelle lies below the wing, but quite a bit of the outside two. Maybe that needs to be taken into consideration. I will get the two outside nacelles shaped tomorrow and think about assembling the wing, electronics and nacelles.

Any suggestions would be welcome!

Len
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Old Jan 13, 2008, 04:17 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
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Today the nacelles were cut, assembled and shaped. The ailerons were cut into the wing and the aileron attachment was glued in. It is easier to do before the top skin is on the wing as the aileron attachment will need to be sanded a bit to a taper. Here is a picture of one of the 5 gram motors and a GWS4530 prop. The ESC is OEMRC (HobbyWing) 6 amp that weighs 6 grams.

The ailerons and servos will be installed next, then the receiver and wiring harness. Then the wing will be covered, then the nacelles attached. I have decided to keep the wing sheeting as intact as possible. The nacelles will be slotted to fit the finished wing.

Len
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Old Jan 13, 2008, 04:28 PM
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's-Hertogenbosch, The Netherlands
Joined Apr 2006
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Hi Len,

it's looking good. If you use a dremel and a sanding tool you can hollow ou that nacelle even more. Be sure to check the servo's before you build them into the wing. How did you fix that prop to the 5 g motor? Did you put in some sort of tube? How does the prop motor colmbination perform?

Robert
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Old Jan 13, 2008, 04:54 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
Hi Robert,

The prop is pretty much friction fit on various sizes of heat shrink tubing carefully anchored with a spot of CA (tried some thread locker first - that is the discoloration). The prop is about perfect. 9700 rpm, 1.7 amps on a 2S 300mah. It will get hit with a black felt tip. It would be nice to find a three bladed 4" prop. The 10 gram motor will turn the GWS 5" 3 blade nicely. Four of those should do a China Clipper in a 48" span. I picked up the Cleveland Models plans for that and the PBY5A in a 38" span.

Len
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Old Jan 14, 2008, 04:47 AM
I NEED a micro seaplane lrf!!!
fabersum's Avatar
Torino
Joined May 2007
295 Posts
Len

I'm interested in small 3-blade props too... planning to need a counter-rotating couple one day (there's a Savoia SM 55X in my dreams).
I started to try drawing something to make with my CNC - here's a pic from Solidworks - maybe we could work together in trying to design something, then I could make a couple and send them to you for testings...

A.
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Old Jan 14, 2008, 03:36 PM
It's a Great Day to Fly
LenBFP's Avatar
Melbourne Beach, Florida
Joined Jan 2002
3,862 Posts
Andrea,

That would be great! GWS makes a pair of counter rotating 5 inch or 127 mm props, but that is as small as I know of. For this 5 gram motor perhaps a pair (actually I would need three) of 100 mm counter rotating props would be super. To began with we could start with three that when the top tip moves to the right (looking at the front of the plane from the rear) the model moves forward. That is what I would call a normal propeller. Its mate would be a reverse.

Len
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Old Jan 14, 2008, 04:21 PM
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's-Hertogenbosch, The Netherlands
Joined Apr 2006
1,419 Posts
Hi Len,

I have been looking at pictures and plans for the do-24. I don't think the original plane has counterrotating props. I think they are all right turn. If they were not, how would you have them rotate? LLR / RRL / LRL / RLR?
I take it from your post that you have not found the 9 cm props like the one I used on the me109? I think I can find some here. If you want me to look for you I can buy and send some. You and Fabersum could do some testing and developping and make a better one (just a bit bigger and more scale perhaps). Send me a pm if you want me to get you some props.

Robert
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