The Atom Special

[Martin McIntosh]

I have built a couple but don`t remember there being a plan.

You will need electric power since a), acceleration on take off has to be gradual to allow the rotor to build up speed, otherwise it will leap off prematurely and tip over to the right, and b), power needs to be coordinated with pitch, roll and yaw throughout the flight, c), it needs to be gradually reduced for landing, not abruptly cut.

This has probably put you off the idea!

[thunderstreak.keith]

thanks martin but not put off. so how is it hoppity was basically the same design but control line?the rotor was spun initialy by hand and then a take off from the ground and hopefully a landing with the 049 still running.(or a crash occured apparently)surely it would work on the same principal? was a plan included i cant remember? still havnt found one in the masses of rcme plan archives in the w/shop

[Alan Gorham_]

The A4 centre spread contains all the detail you need apart from the rotor drawings. There is no other plan to look for so don't bother!. Rich Harris the designer has a pdf of the rotor plan in his photo gallery but it's a bit small to read easily - you could pm him and ask for a copy - he's a helpful sort of chap!

Re power, I think an 049 will not be enough. If you read the thread, there are a couple of examples that have a .12 glow installed and of course they are throttled.

Edited By Alan Gorham_ on 16/05/2018 13:11:22

[David P Williams]

Yes there wasn't the normal pull-out plan, the parts were printed on the magazine pages. I made an electric powered one to the plan and article (and extensive thread on here), and then enlarged the plan by 10% and built second powered by an OS15. Both fly well.

[Richard Harris]

The Atom was designed quickly specifically for the Special and to fit within a few pages of the magazine, there was no full plan only the templates and the instructions. The whole concept of template/write up worked as there were well over 100 examples made around the time that I knew to.

I agree with the above, just don't think an 049 will have enough power. No reason at all why you couldn't convert the Atom to control line, though there is no need for a flapping head as per the RC version.

My Dad still gets his control line stuff our from time to time and we were working on a profile Kayba that could be switched from CL to RC, the CL version works well but the RC version never progressed past the design stage through one thing or another.

The head is fixed at around 7 degrees rearward tilt (I can get a more accurate measurement for you if you like?), the blades are profiled and are rigidly fixed to a blade holder with negative incidence machined in. The blades rotate in a clockwise direction and  will automatically try to make to machine roll left keeping the lines taught.

Motor fitted is an OS 40 with a throttle operated off a servo through an old 35 meg receiver, he has utilised 35 meg innards of Futaba challenger transmitter which he holds in his left hand. You will notice there is a rail sticking out of the fuselage, this is a guide to keep the control wires away from the and as per the fixed wing CL is located on the CG.

Hope this lights the wick and please let us know how it goes?

 

Rich

Edited By Richard Harris on 16/05/2018 15:22:22

Edited By Richard Harris on 16/05/2018 15:23:10

Edited By Richard Harris on 16/05/2018 15:24:31

[thunderstreak.keith]

ok all, well I will still have 4 o49 in boxes. but i do have a lovely.12 brand new in box. Other than that the mag is complete so I can get on with it. a nice interestin project . will the 12 be big enough do you think?

[Hendi Bosman]

Hi all. Hope you guys are well. So, in 2015 I started building the Atom, but everything came to a halt after the birth of our twins. Recently, after being stuck at home after an operation, I decided to unpack my building stuff. All that was left to do, was make blades and cover the atom. The blades are getting me under though. Seriously. The three "blanks" weigh 27g, 26.9g and 25.8g. So, wood selection was okay. Off to shape them to profile. Dimensions are 60mm x 450mm. Actually not as difficult as I thought. Then I came to finding the chordwise Cog. And this is where I am stuck. The chordwise CoG is just too far back. Instead of the triangular FG plate I made the revised one from a pdf that I got from another site from Rich H. If I understand correctly, the mounting hole should be 430mm from blade tip, 1mm behind the chord wise Cog. In saying that, I suppose every blades' mounting point should be the same? I don't want to sand down too much more towards the rear of the blades, out of fear for losing profile. The Centre mark of the blades were all within 3mm so obviously my initial sanding was not too bad. Please help?

[Hendi Bosman]

[Martin McIntosh]

I found that by far the best way is to buy the ready made blades. There is very little work required. Other than that, make sure that your L.E.`s are completely flat with no rounding off or you will need to increase the negative packing pieces considerably.

[Richard Harris]

Hendi,

Glad to hear you are back on track with some modelling, it has been the same story with myself. Our daughter was born in 2016 so modelling has been put on the back burner, now she is on her own two feet I have managed to get out to the field once or twice. As for designing and building the urge is starting to come back but time is the limiting factor right now.

Regarding your blades, you have made a good job on their profile and your weights are very close, any chance you could take a photo of where your CG lies please? If it is a mile out there are a few tricks we can use to bring it into a more useable position.

Unfortunately AJ blades went out of business so the Atom blades are no longer available, that said, I am willing to make up sets at cost for anyone who requires a set but would need notice to get materials.

 

Rich

Edited By Richard Harris on 15/06/2018 12:25:04

[Hendi Bosman]

Hi Rich. Thanks a lot for your reply. Sadly I am in South Africa so I won't even consider asking you, but I appreciate the offer. Out of frustration I reduced the width of my blades from 60mm to 52mm, which I got from Steve Jones 2's posts on page 7. Even though this did bring the CoG forward slightly, it is still too far back. I will take a photo and put it on. I was so excited about finally finishing my Atom. I will order some more wood as soon as somebody can bring some, as I live in a very small town. Maybe the weight of the spruce was too light compared to that of the balsa?

[onetenor]

Re rolling in to the left> I presume you fly clockwise. Is that so?

[onetenor]

You might find the head you want here---- https://www.google.co.uk/search?q=helicopter+parts&oq=helicopter+&aqs=chrome.2.69i57j69i65j0l4.17509j1j1&sourceid=chrome&ie=UTF-8

Loads on this page

[lee pering]

Hi all

looking for advice on the amount of control throws people are using on the Atom.

[bees]

Hi, Iam in the the process of building the Atom and was wondering it would be okay to fly with out the canopy leaving a open cockpit, Thank you.

[Martin K]

Hi bees,

sure, it will fly just fine without the canopy. At least mine does

[bees]

Thank you, could you please comfirm that the blades are 600mm chord wise but what length regarding span wise

[Richard Harris]

Bees,

60mm chord, 430mm long. As Martin has said the canopy makes no difference to the flight characteristics of the Atom.

There are a few PDF's HERE that may come in handy? just scroll down to the Atom blog and you will see them.

Good luck with yours, any questions just ask!

Rich

[bees]

Okay thank you.

[John T]

Ever since I got my Autumn 2014 RCM&E, the Atom has been on my 'build' list, but what with one thing and another I never quite got around to it. A few weeks ago I found I had a bit more building time available than usual due to the unfortunate present situation, and I've finally made one.

I've used a C30 Razor autogyro head from Malcolm at Coolwind Models and fixed the receiver behind the mast on F4 as it seemed a bit too 'cosy' under the canopy. The motor is an Airmax 2826 1000Kv with a 9 x 4.5 prop, According to my Watt meter this combination is pulling about 122W maximum.

Will this be enough or should I buy a 9 x 6 prop? The ready to fly weight, including battery is 610g.

[Richard Harris]

John,

Good to hear that you have got round to building your Atom, these extra building hours are perfect for trying something different.

I think you will be ok with your power output but there really is only one way to find out!

Please add a few photos if you get chance?

Rich

[John T]

Thanks for the reply Rich,

Here are a couple of photos taken in the back garden. As you can see, I've shamelessly nicked the colour scheme from your original article. The tail booms were supposed to be red from an old Wilco rattle can, but for some reason the last dregs came out as brown.

It may be some time before I get the chance for any flying shots...

[Richard Harris]

John,

You have made a nice job of your Atom I look forward to hearing how the maiden goes when ever that may be.......

Rich

[John T]

Well, my Atom finally got its maiden flight yesterday, though with somewhat mixed results...

On the first attempt I gave the rotors a spin by hand, but even with full back stick while moving slowly into the breeze the rotors seemed a bit reluctant to spin up. After about 50 yards they suddenly seemed to speed up, so I released the back stick and with a bit more throttle it was flying.

There seemed to be plenty of power available with this set up. However, it was wanting to roll to the right despite having about 3 - 4 degrees of left tilt on the rotor. I was also having to fly with a lot of forward tilt.

After about half a dozen circuits I'd managed to kid myself that I was in control, so I decided to try and land it to sort the trim out. That's when I discovered it wasn't a good idea to bank it too steeply as it dropped out of the sky into some long grass. Much to my amazement there was no damage.

Before the next attempt I lowered the left hand control rod slightly, thinking this would give a bit more left roll and also reduce the rotor pitch at the same time. After another long take off run it was airborne again and I realised the boundary fence around the patch was very close. Without thinking I banged the throttle wide open, and before I knew it it was three quarter of the way through a loop.

I wasn't so lucky this time and broke the mast and the prop. Other than that there was no damage, but as I didn't have a spare mast with me I called it a day.

Before I try again do you think it would help to increase the shim thickness at the back of the rotor blades a touch? I wonder if this would help the spin up and also reduce what appears to be excessive lift a bit.

I can see why this autogyro lark is so addictive. It's a totally different ball game from fixed wing flying.

[Richard Harris]

John,

Its addictive isnt it?

If you are going to add extra shim to the blades use masking tape strips and do it gradual until the sweet spot is reached.

Looking forward to another flight report

Rich