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Convert Black Diamond

Black Diamond begging to be converted

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Tomas Dunker18/08/2014 16:04:02
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In RCM & E (Aug 2014), I read in Column Fly Electric by Nigel Hawes about Slope Soarer Black Diamond. I became curious and bought the plan on the model (RCM & E plan service ref. No. RC1661).
What made me most curious was that "Black Diamond begging to be converted to electric power."

- Is there anyone who has built and been flying the model? I've thought about doing it with twin motors and one (1) landing wheel under the body and two small support wheels under each wing tip (see sketch).
The model having no rudder, instead Diffrential thrust mix into the motors. Works very well on my latest project. See **LINK**

- Would be nice to hear what you think and feel.

Black Diamond Twin Sketch

Edited By Tomas Dunker on 18/08/2014 16:36:03

Trevor18/08/2014 17:12:58
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506 forum posts
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Hello Thomas,

When the original Black Diamond was built, Futaba 138s were the latest thing in servos, being less tall than the 128s - exciting stuff! If I were building another one now, I'd put separate aileron servos in each wing and separate elevator servos too. Then the elevators could be put on a V-tail mix to provide a rudder function.

That said, I agree that differential thrust is a viable alternative - I have a rudderless P38 which works the same way as your Bronco.

The idea of the twin motor configuration and mono wheel/outrigger undercarriage looks brilliant! I hope you will continue this thread as a build log.

Enjoy the build,

Trevor Hewson

www.bartonhewsons.me.uk

Tomas Dunker18/08/2014 18:50:18
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Thanks Trevor for your feedback.

To fit the battery (LiPo) in the body and get the CG right, I will build the wing completely finished with the motor (2), ESC (2), servos (4) and Rx. see
**LINK**
Then it will be easier to get CG right. The body I have to probably lengthen and make a little wider.

PS I'm not so good at English but I hope you understand what I mean?

Edited By Tomas Dunker on 18/08/2014 18:53:46

Trevor18/08/2014 19:40:03
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506 forum posts
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Yes, the nose on the original was designed to hold a pack of 4 AA cells so you will need to enlarge it to accommodate say a 3s 1500mah LiPo. It might even take a 2200mah pack to balance it so your idea of building the wing first then redesigning the nose accordingly is very wise.

Have you any thoughts on colour scheme? Something less reptilian than the original, I assume!

Trevor

Tomas Dunker20/08/2014 15:02:53
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black_diamond_01_1k2px.jpgDivided plan. Easier to scan the ribs for printing and making templates

black_diamond_02_1k2px.jpg
The very first ribs made!

Trevor20/08/2014 19:51:44
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Nice to see the project off to such a quick start Tomas! Luckily for you, it wasn't me who drew the plan. Instead a draughtsman friend of mine made the plans from my prototype, building another one as he went along in order to prove his drawings. I think there is a picture of the two prototypes together somewhere on my website.

So, whilst you might find a few places where you would have liked a bit more information, hopefully there won't be many actual errors.

I hope the build goes smoothly.

Trevor

Tomas Dunker23/08/2014 17:41:19
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black_diamond_s_mont_0k897p.jpg
As the ribs in the wing center section is mounted inclined, I made a tool to sharpen the angle.

Nigel Hawes28/08/2014 19:40:17
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Hi Tomas,

Great to see you are also building a Black Diamond with a view to electric power.

Please keep me informed of your progress, as it will probably be quicker than mine - I have a huge backlog to get through!

Nige.

Tomas Dunker03/03/2015 13:01:49
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Time passes and sometimes becomes a project put aside because others (Atom, Kwirl, Backyard Canard and NotForSale) come in between.
But now I'm back to the drawing at Black Diamond.
I have got the powertrain and thinking about how I will construct the engine nacelles?
This project can take its time...
black_diamond_03_1k2px.jpg

Edited By Tomas Dunker on 03/03/2015 13:05:46

Edited By Tomas Dunker on 03/03/2015 13:08:03

Tomas Dunker20/03/2015 08:19:34
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84 photos

black_diamond_04_1k4px.jpgThere were some trix to fit the ribs front angle to the false leading edge. You have to think in three dimensions, not a single 90 degree angle. I took a sanding block and used the plan as a guideline.
black_diamond_05_2k0px.jpg

Tomas Dunker22/03/2015 10:50:41
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76 forum posts
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Test assembly:
What about dihedral braces in the wing center? Needed them or not? Do you have any suggestions?
black_diamond_10_1k6px.jpg

Edited By Tomas Dunker on 22/03/2015 10:54:13

Dave Hopkin22/03/2015 11:50:07
3672 forum posts
294 photos

I would but then again I am paranoid about wings doing a golf clap at 100 feet blush

Trevor23/03/2015 08:48:10
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506 forum posts
61 photos

Hello Tomas,

It's good to see you are making good progress with your Black Diamond. The original had no dihedral braces, relying on the fact that the wing section is so deep at the centre and the fuselage pod and tail also provide some support.

Of course your motorised version will be a bit heavier and probably capable of flying faster which means that it will be possible to pull more g-force than with the original slope version, so there would be no harm in reinforcing all three dihedral breaks.

All the best,

Trevor Hewson

Tomas Dunker25/03/2015 19:03:25
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76 forum posts
84 photos

black_diamond_13_1k6px.jpg
Servo for one of the elevators.
black_diamond_12_1k6px.jpg

Tomas Dunker01/04/2015 16:07:53
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Glue together the inboard wing panels.
black_diamond_14_1k6px.jpg

Next comes the hardest part: Motor nacelles!
I have done nacelles earlier on a wing with constantchord and without dihedral, see my website >> **LINK**

On Black Diamond this becomes more difficult with all these angles!
First, I made templates from cardboard to see how and if it works?
black_diamond_16_1k6px.jpg

Edited By Tomas Dunker on 01/04/2015 16:11:54

Trevor01/04/2015 17:37:08
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506 forum posts
61 photos

Ah yes, the problem of no straight lines to refer to! I had a similar issue with the sponsons on my Aquabird and, like you, did a cardboard mockup first to get everything lined up.

http://www.bartonhewsons.me.uk/home/modelflying/sport/aquabirdprojectd.html#February

I'm really looking forward to seeing how this powered conversion works out.

Trevor

Edited By Trevor on 01/04/2015 17:41:19

Tomas Dunker06/04/2015 15:27:48
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The construction of the nacelles

black_diamond_19_1k6px.jpg
Outer nacelle-side in line with rib w5.

black_diamond_24_1k2px.jpg
Motor former and inner nacelle side.

black_diamond_27_1k6px.jpg
Test mounting motors.

Tomas Dunker16/04/2015 08:33:04
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76 forum posts
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black_diamond_29_1k8px.jpg
Dihedral braces between inboard / outboard wing panels

Tomas Dunker17/04/2015 17:00:31
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76 forum posts
84 photos

Question: 'The part' located between the aileron and inboard wing panel (see attached picture), what is its function? Can I extend the aileron so it ends against the inboard wing panels?
skevbredd.jpg

Trevor17/04/2015 18:20:22
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506 forum posts
61 photos

Hello Tomas. Extending the root of the aileron to the dihedral break will be fine. Good to see the build making steady progress.

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