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The Atom Special

A simple to build, tough autogyro with racy looks

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Hendi Bosman06/12/2015 14:29:11
8 forum posts
1 photos

Thanks Bob!

Ozgur Sar01/02/2016 06:58:37
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28 forum posts

My latest Atom Autogyro flying of this year...

https://www.youtube.com/watch?v=6Dp3Sk6KeRs

Richard Harris03/02/2016 21:09:53
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1907 forum posts
1735 photos

Ozgur,

Your Atom flies well, I like the landing. Thanks for sharing thumbs up

Rich

Ozgur Sar04/02/2016 08:48:12
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28 forum posts

Rich,

Thank you for your comment. Yes it flies well but currently very inadequate power due to the excessive reinforcements I have made on the model. I guess it is close to double the weight it should be but I don't have time to build a new light one.

But in spring I'm looking forward to building a pusher model from scratch 1.5x size of atom.

Hendi Bosman03/04/2016 09:15:15
8 forum posts
1 photos

Hi all. So since I last posted, and sadly, built, I have spent 4 months away from home for work. And then also been getting the nursery ready for our twin boys who should be arriving shortly! Okay so 0.8mm sheet for the head received from HK. Also, laminated my 6x6 spruce and balsa for the blades last night. So here is my next question. Actually two questions. Firstly, Steve Jones 2 has some pics early in the thread on his blades. At the root I see they are not square but runs slightly diagonaly from TE to LE. Dete Hasse I see yours is square? May I ask why please? And then is there a template somewhere for how the blade narrows towards the root?

Regards

Hendi

Steve Jones 203/04/2016 10:09:00
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476 forum posts
349 photos

Hi there Hendi

The angle at the root I think is designed to create a slight blade angle change as it bends up. The more experienced auto it's will fully explain I am sure..

For this size it probably does not matter if left square , I have both

As for the width at the root I usually use the reinforcement plate width then find a dinner plate and blend z large radius , again not critical.

Look forward to seeing the finished model and successful flights

Steve

Hendi Bosman03/04/2016 10:33:29
8 forum posts
1 photos

Hi Steve.

Thanks so much for your reply. Okay so at first I will stick to a square root and see how that goes. I found some pdf's on another forum for a slightly modified FG plate on the head. Instead of a triangle its slightly more square where the 3 blades attach. But for now it is blade making for me. As a real life heli pilot the concept of making blades boggles my mind as I know how precise they have to be. Actually had a bery scary experience just last week with a heli tune where one blade's tracking was waaaay out. But anyway, thats me off topic. I will post some pics of my blade attempt soon.

Regards and happy landings

Hendi

Steve Jones 203/04/2016 10:47:49
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476 forum posts
349 photos

Glad to help, yes the other head plate was drawn up by another Atom builder to give the blade root and in particular the shim strip a greater area to text on. The flex of the plate was not affected. Malcolm at Coolwind Models offers these revised plates CNC cut, I have one and they are great as they are a bit more tricky to cut out accurately. The standard triangular are perfectly OK.

Making blades is straight forward, remember the leading edge must be sharp, not rounded, as this help with spin up. Most critical is balance as you know . It will fly if not but the model shake is not good.

Steve

Tomas Dunker07/04/2016 04:42:20
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70 forum posts
83 photos

I discovered that my fiber glass head plate is 1 mm thick (even though I ordered 0.8 mm).
Is that why my Atom is so difficult to fly? Head plate is too stiff?
If so, can I modify it in any way?

Ozgur Sar07/04/2016 04:57:52
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28 forum posts
My blades were extremely bending in air so I doubled my plate.

However I am sure some that flexing is required for proper flight
Steve Jones 207/04/2016 20:45:17
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476 forum posts
349 photos

Thought I would start new thread to keep whippit one clean..

So my blades on my 2 blade Atom are as follows:

Length 550mm, width 57mm, bolt hole 20mm from root, root width 40mm, weight 47g, span cog 225mm from tips.

Weights 2x 90mmx3mm plumb solder glued 15 in from tips. Weights 5g each giving 10 per blade.

Construction leading edge 6x6mm spruce , remainder 6mm firm balsa

Rotor hub 1.5mm GRP, 140mmx 30 with blade holes 100mm apart. Who's glued to hub 0.8mm

Hope this helps

Steve

Edited By Pete B - Moderator on 24/04/2016 18:16:35

Tomas Dunker08/04/2016 22:06:41
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70 forum posts
83 photos

Suddenly it looks very strangely out here on the forum, what happened?

Pete B - Moderator24/04/2016 18:18:52
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Moderator
7349 forum posts
694 photos

Thanks for the report, Tomas - I've taken the formatting out of Steve's post and it seems to have fixed it....thumbs up

Pete

Tomas Dunker24/04/2016 18:50:47
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70 forum posts
83 photos

What happens with the flight characteristics when the head plate is 1 mm thick instead of 0,8 mm?

Steve Jones 224/04/2016 20:02:53
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476 forum posts
349 photos

Great, sorry I messed things up with my iPhone post , you beat me to it as I was going to ask to delete of fix things. Will try and be more careful

Steve

Richard Harris25/04/2016 18:06:35
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1907 forum posts
1735 photos

Thomas,

You should'nt really see a difference between 0.8mm and 1mm thick FG plates, but if you feel the 1mm is significantly stiffer just increase the size of the triangle by about 10mm, remembering to move out the blade mounting hole positions.

Here are a few snaps of Steve's 2 bladed Atom taken yesterday at Thames Valley and district MFC, it flew viceless thumbs up

img_8985.jpg

img_8991.jpg

img_8992.jpg

Rich

Tomas Dunker26/04/2016 06:25:21
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70 forum posts
83 photos

What happens with the flight characteristics when the head plate is stiffer?

Richard Harris26/04/2016 21:58:51
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1907 forum posts
1735 photos

Tomas,

A stiffer plate reduces the lag angle which causes the nose to pitch upwards with a tendency to have a more central (in some cases right roll trim with an anti clockwise rotor) rotor disc due to asymmetric lift. A free flapping hinge has a lag angle of 90 degrees, stiffen the hinge and it reduced this angle.

 

Basically it will push its nose upwards, sometimes over the top (and don't ask me how I know that! embarrassed)

 

The best heads are those that are  fully free flapping hinge (as per Cierva) with the cone angle being controlled by the mass of the blades. Go back 10 years and this type of head was the norm in the rc world, Fibre Glass sheet is a relatively newer and simpler idea.

 

Rich

Edited By Richard Harris on 26/04/2016 22:00:33

Steve Jones 226/04/2016 22:20:16
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476 forum posts
349 photos

Thanks Rich, great pictures as ever.

Yes the 2 blade set up from your plan goes really well , smooth to fly and hardly any power to fly level. The 3 blade set up is more responsive if you want to have some fun but I love the 2 blade as it sounds great and is a joy to cruise about with those low passes

Steve

Tomas Dunker27/04/2016 06:58:05
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70 forum posts
83 photos

Thanks Rich, now I understand why my Atom is so 'unruly' in the air.
Instead of making a new plate (hard to get 0.8 mm glass fiber in Sweden) I am considering to drill small holes
(1-2 mm dia) according to attached picture, to get my 1 mm plate more flexible.
Could it be a good option?
1mm plate.jpg

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