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Double Diamond

C of G conundrum

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Dwain Dibley.28/08/2016 18:05:08
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1270 forum posts
1265 photos

Hello Folks,

It's been a while since I posted, and about a year since I did anything model wise. Good to see some familiar names still here.

In my workshop I have a Ben buckle Double Diamond, Electrified and all ready to go.

The problem is if it balances on the spar I have to add about 500g of ballast at the front. I am pretty sure that the tail feathers that came with it ( it was already built when I got it) are not correct. They are way to big and heavy.

There are two options,

1. Find a plan and build a new set and replace the ones I have fixed on.

2. Find the correct C of G and just add the lead.

So, to the question, has anyone got the info on the C of G or a copy of the tail feathers plan they can email across.

Cheers,

D.D.

Dwain Dibley.28/08/2016 18:24:01
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1270 forum posts
1265 photos

[IMG]http://i147.photobucket.com/albums/r290/Crewie3fords/IMG_20160828_174524_zpskdhxmqpd.jpg[/IMG]

[IMG]http://i147.photobucket.com/albums/r290/Crewie3fords/IMG_20160828_174612_zpssvrjcisq.jpg[/IMG]

[IMG]http://i147.photobucket.com/albums/r290/Crewie3fords/IMG_20160828_174459_zpswfeumnmr.jpg[/IMG]

[IMG]http://i147.photobucket.com/albums/r290/Crewie3fords/IMG_20160828_174547_zpsoyr9oax3.jpg[/IMG]

Dwain Dibley.28/08/2016 18:27:10
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1270 forum posts
1265 photos

[IMG]IMG_20160828_174524_zpskdhxmqpd.jpg[/IMG]

Dwain Dibley.28/08/2016 18:29:08
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1270 forum posts
1265 photos

**LINK**

bert baker28/08/2016 18:31:23
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1482 forum posts
305 photos

Looks to me like the c-g should be further back of the main spar.

Basickly on the side frame there are windows

The forward side window rear bar that slopes towards the front, will give you and Idea where it is the lowest edge take a vertical line up to wing seat.

Denis Watkins28/08/2016 18:39:46
3929 forum posts
61 photos

If this is the 8 foot wingspan model, with the recommended 60 motor on board, then the 500 gram front end was catered for in the design, and the model has the ability to carry such weight.

bert baker28/08/2016 18:46:51
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1482 forum posts
305 photos

Give Colin Buckle a ring he will be able to tell you.

Dwain Dibley.28/08/2016 18:49:20
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1270 forum posts
1265 photos

Hello chaps, the span is 88".

img_20160828_174459.jpg

img_20160828_174524.jpg

img_20160828_174547.jpg

img_20160828_174612.jpg

As you can see from the last pic the tail plane is not as per plan, and is bigger and heavier. I will see where that comes out re the window frame.

Dennis, are you saying adding the weight will be ok ?

Just figured out how I used to post pics LOL.

Cheers

D.D.

Dwain Dibley.28/08/2016 18:50:56
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1270 forum posts
1265 photos
Posted by bert baker on 28/08/2016 18:46:51:

Give Colin Buckle a ring he will be able to tell you

That's too east matey......LOLwink

Cheers

D.D.

Dwain Dibley.28/08/2016 18:53:49
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1270 forum posts
1265 photos

Also , if a sixty was the recommended engine, my leccy alternative is probably way lighter even with the lipo.

frown

I have also built this, a Great News, which flys beautifully.

img_20160725_122418.jpg

Cheers

D.D.

bert baker28/08/2016 18:59:08
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1482 forum posts
305 photos

Even if it were rubber band propelled the c-g is the c-g.

Looks nice plane you have there.

Denis Watkins28/08/2016 19:22:19
3929 forum posts
61 photos

Yes DD and Bert, C of G goes where it belongs. Old 60s could weigh a pound, 1lb, so I was just adding that BB expected the model to fly with quite some weight already up front. Lightweight electric gear may need additional weight, also it will maintain authority in the air

bert baker29/08/2016 17:35:00
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1482 forum posts
305 photos

Great News,LOL..

I understand where you are coming from my old Flair Fokker Tri plane had half the local church roof up front.

Edited By bert baker on 29/08/2016 17:36:40

Dwain Dibley.29/08/2016 23:53:44
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1270 forum posts
1265 photos

Found this Guys.

4.jpg

bert baker30/08/2016 09:12:08
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1482 forum posts
305 photos
Posted by bert baker on 28/08/2016 18:31:23:

Looks to me like the c-g should be further back of the main spar.

Basickly on the side frame there are windows

The forward side window rear bar that slopes towards the front, will give you and Idea where it is the lowest edge take a vertical line up to wing seat.

That was what I was talking about,, probably not the best way to say

Dwain Dibley.31/08/2016 23:47:11
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1270 forum posts
1265 photos

You were right Bert, and many thanks to you and Dennis for the good advice. Also if you notice on the plan it says an even more rearward C of G helps the glide. Local vicars can sleep peacefully in the knowledge I will not be scampering over their roofs. angellaugh

I will post as to how the maiden goes .

Cheers

D.D.

Dwain Dibley.06/02/2017 11:36:33
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1270 forum posts
1265 photos

I have just (yesterday) crammed 500g of church roof into the front of the Double diamond.

I cut a hole and put 250g either side in the nose, fixed with screws. I then squirted in some expanding foam, sealed the hole with balsa and covered with red solartex.

No excuses now.

will it fly ??????????????

D.D.

Dwain Dibley.10/02/2017 00:20:47
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1270 forum posts
1265 photos

I put the double diamond on the balancer only to discover it still needed some ballast to achieve the (alleged) correct C of G.

Another 120 g to be precise.

So surgery was performed once more and said lead was inserted in the nose.

img_20170209_110529.jpg

img_20170209_110555.jpg

img_20170209_112004.jpg

 

Edited By Dwain Dibley. on 10/02/2017 00:28:44

Dwain Dibley.25/05/2017 00:11:10
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1270 forum posts
1265 photos

Ok Chaps........

Thread resurrection in progress...........laugh

Today I can proudly announce the Maiden flight of the Double Diamond was without trauma, and I have video evidence to prove it.......

Thanks to all you Guys for your help and advice, and thanks to my mate Johnny for his assistance with the rebuild and help today at the field. thumbs upthumbs up

Enjoy the Crazy video, the local accents and the mental Bee Storm. We were suddenly engulfed in a massive swarm of Bees, they weren't bothered by us and they just bounced off but it was a tense moment or two.

Pics and vid in a bit.

D.D.

Dwain Dibley.25/05/2017 00:23:11
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1270 forum posts
1265 photos

img_20170524_101708.jpg

Tranny on wing for scale.

img_20170524_101739.jpg

Couple of scenic shots of where we fly.

img_20170524_094932.jpg

img_20170524_095211.jpg

Vid. Enjoy.

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