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Old Oct 14, 2012, 04:27 PM
flyin' fool
goldguy's Avatar
Vancouver Island, Canada
Joined Jul 2003
7,257 Posts
I was going to go for an Atom, but looking at my stock of raw materials, I though I could come up with something waaaaay cheaper. Just the airframe build cost me about $10 CDN. HK models are great prices, but the shipping kills your wallet. The Atom really isn't an under $30 model, more like $55 to my door. I posted the Pup since anyone interested in an Atom might want to consider scratch building a 'similar' design.

And yes, it flies great, I flown it in the park, on the slope and even indoors.
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Old Oct 16, 2012, 04:15 PM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
4,034 Posts
Installed the 3.7 g servos and here are the pictures for anyone interested. Will post flight report and video once I've given them a spin
Andy
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Old Oct 19, 2012, 12:38 PM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
4,034 Posts
Maiden flight completed and the aileron servo mod was a total success. It now tracks really well and there is no need to input opposite commands to straighten her out. I think HK should junk the rudder and install ailerons instead as it's much better behaved and would be easier for a newbie to fly. It coped with the extra weight although the power produced from the stock brushed motor is never gonna get my pulse racing. It will even roll albeit not very axially and such stunts are best performed with some height as it tends to drop somewhat.
It was getting dark so vid is too grainy to post but I will try again over the weekend.
Andy
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Old Oct 19, 2012, 01:49 PM
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Joker 53150's Avatar
United States, WI, Muskego
Joined Sep 2012
834 Posts
We finally got to maiden ours as well today after three weeks of waiting for calm winds.

It's my son's plane, but he had me go first to make sure it worked and to trim it up for him. I started with a completely stock plane (does removing the epoxy from the elevator pushrod mean it's no longer stock?). The hand-launching was completely uneventful. No thrust-roll, no diving for the ground, nothing but a nice & easy start to the flight. I kept feeding it trim but never did get it to fly straight with neutral sticks. Possibly lack of rudder authority or maybe some slight wing-warpage others have mentioned on previous posts?

Either way, it flew. I tried to gain some altitude so I could turn the radio over to the boy, but noticed that it had a really hard time gaining any substantial altitude. I was running the stock 250 mAh 15C Li-Ion battery and figured it could just be maxed out. Even at WOT it was hard to gain any altitude, so I landed it and swapped batteries. My back-up batteries are Zippy 500 mAh 20C LiPos. They take up quite a bit more room in the nose and I was concerned with balance due to the extra weight. After launching it I can honestly say I didn't notice any difference in how it flew, as it still had a hard time gaining altitude. Most of the flight was spent screwing around with the trim and getting used to the new plane. We both got in multiple flights on the original battery and one of the two Zippy batters I brought.

Landings were a little more exciting than I had expected, mainly due to the constant turning. We cart-wheeled it a few times, the boy ran one wing into a soccer goal, and a couple landings were smooth as silk. If/when we get the turning issue figured out I think it'll be a dream to land.

The last "landing" by the boy ended in a minor cart-wheel, which bent the prop. I didn't bring the spare, so we called it a day. When I tested the battery later I found it was down to about 45%. The 250mAh was around 80%, but this battery saw very limited use before I swapped it.

Here are a couple other observations:
- I am going to add some clear packing tape to key areas for strength. It worked wonders on my Super Cub. The trick here is limiting it to avoid the weight penalty.
- Maybe a brushless upgrade in the future? The stock motor/prop is just too weak. I'd rather have power and not use it instead of constantly flying at WOT and wishing for more.
- The nose split from one of our more "aggressive" landings. Possibly due to the wider/heavier battery I stuffed in there. Either way, it's an easy fix.
- The stock rudder gives crap for control. It's going to be enlarged to give the plane some authority in turns. Ailerons would be preferred, but I'll skip that for now.
- Elevator seemed fine for the style plane. There wasn't enough authority to do a loop, but with this style plane I'm not planning on needing that much throw.
- The 500 mAh battery gave us plenty of time to fly compared to the stock 250.
- One landing resulted in a damaged prop, so we're down to the last one that came with it. Time to place another order with HK!
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Old Oct 19, 2012, 02:32 PM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
4,034 Posts
Nice flight report. Ailerons are super easy to install and turn it into a much nicer model. I agree that's it's underpowered so I've got a b/less motor standing by which i'll install shortly
Andy
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Old Oct 19, 2012, 04:01 PM
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Joker 53150's Avatar
United States, WI, Muskego
Joined Sep 2012
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Thanks, I might just "accidently" place an order with HK today for a new motor and ESC.

In the meantime it was time to fix some of the issues that came up today on the maiden. First the split nose was epoxied back into shape. Some strips of clear packing tape were added to strengthen it and to give a smoother bottom for landing. I also added a little to the leading edge of the wing and some around the prop.

The big change was the increase in rudder area. As said earlier, the stock rudder sucks. Well, I didn't say it quite like that, but I'll stand by that statement. Even with the trim at max it wouldn't stop the turn. With the increase in rudder size I expect that problem to go away. To make it happen I carefully removed the stickers and extended a line following the stock hinge line. I tried creasing it similar to the stock hinge, but it was still too thick and hard to move. "Plan B" was to trim a little extra foam from the hinge which let it flex very easily. Some packing tape on one side was added to strengthen the thinner foam and the stickers were then replaced.

At this point I essentially had two rudders, one high and one low. At first I was going to add a thin strip of carbon fiber between the two of 'em, but I didn't have the right size piece. The piece I have turns out to be the same width as the vertical stab, so I just cut it to length and epoxied it on the trailing edge of the rudder. A small piece of packing tape wrapping it holds it all together nicely while the epoxy dries.

I tested it a few times and it bends just like it was made that way. I can't wait to give it a shot!
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Old Oct 19, 2012, 04:08 PM
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Joker 53150's Avatar
United States, WI, Muskego
Joined Sep 2012
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Oh, and for giggles I put the Watt Meter on the plane after doing the work this afternoon. It's pulling about 3-1/2 amps and 27 watts.
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Old Oct 19, 2012, 05:10 PM
Silly n00b
TuMadre's Avatar
United States, NC, Charlotte
Joined Sep 2011
647 Posts
Quote:
Originally Posted by Joker 53150 View Post
Oh, and for giggles I put the Watt Meter on the plane after doing the work this afternoon. It's pulling about 3-1/2 amps and 27 watts.
It's no wonder it doesn't get your heart racing.

I like the rudder mod - let us know if it improves handling.
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Old Oct 19, 2012, 07:18 PM
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United States, WI, Muskego
Joined Sep 2012
834 Posts
A racing heart would be nice, but what would be better is the ability to climb! I "accidently" placed that order with HK... To make it more fun I ordered two different motors and four different size/pitch props. Whatever doesn't get used now will find a home on a later project!

The original brushed motor and ESC will probably find a home in a scratch-built foam-board plane.
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Old Oct 19, 2012, 08:44 PM
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United States, WI, Muskego
Joined Sep 2012
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My son took some video of the maiden flight, expecting some destruction.

Atom Maiden (0 min 47 sec)
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Old Oct 20, 2012, 01:29 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
4,034 Posts
Brushed v brushless

Quote:
Originally Posted by Joker 53150 View Post
Whatever doesn't get used now will find a home on a later project!
Spoken like a true scratch builder

The original brushed motor and ESC will probably find a home in a scratch-built foam-board plane.
No it won't! When you feel the superior power output from brushless motors of half the weight that redundant brushed motor and esc will be filed in that gray box on the floor. Been there, done that.
Andy
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Old Oct 20, 2012, 06:26 AM
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CPMBOY's Avatar
Malaysia, Sabah, Kuala Penyu
Joined Aug 2011
721 Posts
motor & ESC...

which motor & ESC are you guys planning to install on the atom?....gonna re-maiden mine soon....it's maiden was not succesfull and its been in the plastic bag for quiet some time...now begging to be released...emm...both the aileron & the rudder mod seems like a good upgrade/improvement
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Old Oct 20, 2012, 09:36 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
4,034 Posts
This is the motor I'm going to install http://robotbirds.com/catalog/produc...oducts_id=2195 and will run either a 4x4 or 5x3 prop and 10 amp plush esc.
Andy
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Old Oct 20, 2012, 10:17 AM
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taz101's Avatar
Australia, QLD, Oxenford
Joined Oct 2010
2,027 Posts
This is the one I am going to go with!!
http://www.hobbyking.com/hobbyking/s...nner_10g_.html


LURCH
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Old Oct 20, 2012, 11:05 AM
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Joker 53150's Avatar
United States, WI, Muskego
Joined Sep 2012
834 Posts
So is it typical to mount the new firewall to the end of the original pod, or do people also just cut the pod up to push the prop farther forward (closer to it's original location when stock)? On the setup Taz shows it looks like you'd gain a little more clearance for a larger prop, but does it also change the flight characteristics as well??
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