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Apr 19, 2020, 04:58 PM
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Hey guys, where do you run the CG on these round planes? Any problem getting it forward enough? Tried an Ellipse type plane a while back, and needed a bunch of lead to get the CG forward. Don't like adding weight to a plane....

Steve
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Apr 19, 2020, 05:27 PM
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dbacon's Avatar
Post # 10 says:
The center of gravity is back 25% of the cord but this is not 25% of the wing area. On a 24" circle the CG is back 6" from the front of the circle.

I hate weight, To minimize the weight behind the CG, I put the servos far forward and used thread for pull-pull operation of the controls. If you can find Dacron thread, it will hold up best and isn't stretchy.
Apr 19, 2020, 05:33 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by Flyboy Steve
Hey guys, where do you run the CG on these round planes? Any problem getting it forward enough? Tried an Ellipse type plane a while back, and needed a bunch of lead to get the CG forward. Don't like adding weight to a plane....

Steve
All the info is on page #1 of this thread . To get a proper CG without adding lead , place all the components ( motor , ESC , servos , receiver , battery , landing gear , etc ) as far forward as is reasonably possible . If that doesn't do it , get a heavier battery .
Last edited by balsa or carbon; Apr 19, 2020 at 05:39 PM.
Apr 19, 2020, 06:29 PM
Registered User
Oddly enough, all my snowballs have ended up nose-heavy. I have from 1/4 to 1/2 oz of lead at the tail. But I like the CG aft of the usual 25%. And with the battery stuck into the pylon, I can’t just slide it aft to fine tune the balance. So I just live with the extra weight. None of my Snowballs are flyweight anyway.

Cheers,
Dave
Apr 20, 2020, 08:02 AM
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Thanks, guys. Appreciate the guidance.
May 12, 2020, 11:16 AM
Registered User
I built yet another Snowball...

I wanted one to fly off water. Earlier this spring I played around in a parking lot that was partly flooded from snowmelt. Used my pink styrofoam ‘ball since it’s the only one I have that doesn’t get waterlogged or fall apart when it gets wet. It worked, had no trouble getting off the water, but its 10” prop was too close to the surface and sprayed water all over the top of the plane, which caused me some worry over my electronics.
So I decided to build a lighter Snowball, with waterproof foam, that could fly with a smaller motor/prop combo. Finished it last night, flew it off grass this morning. Seems like it may be the ticket.
It’s 24” diameter, powered by a 2208 1450 kv motor, unlabeled but I think a Suppo. Currently running an 8x4.5 prop. May try others but it flies great as it is. I first flew it with a 1000 3s pack, and it had so much power I rarely got over 25% throttle. Switched to a 1300 2s and liked it better. Still more than enough power. It weighs 10.5 ounces with the 1300 2s, an ounce less with an 850 2s. Pretty light for a 24 inch Snowball, my EPP and pink foam versions weigh close to a pound.
I used DTFB with the paper peeled off, doubled the front 40% to add stiffness, and glued strapping across the bottom. I made the floats longer than my others to hopefully help out on the water. Also added an equipment nacelle to protect the receiver and ESC from spray. Not totally watertight though, so if I turtle it they’ll get wet.
Love the way it flies! It just floats and dances, just like my latest nutball. It would probably be better with a lower kv motor; I have some 1100kv 2208s but they’re in other planes at the moment. My heavier EPP version is still better in wind, no surprise there, being half again heavier.
So, just waiting for a chance to try it on water. Will let you all know how it goes. Maybe take some video.

Cheers,
Dave
May 12, 2020, 11:42 AM
Learning to make
That is LIGHT
Under 300g with a 1300mAh pack must mean super long flight-times?
May 12, 2020, 01:19 PM
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dbacon's Avatar
Yeah that lightness is wonderful!

On prop size, you can reduce the prop diameter by 15-20% and add another on the shaft in an X fashion, and it seems to produce the same pulling power with the same current draw.

It also allows selections of props with a shallower pitch.
May 12, 2020, 04:31 PM
Registered User
As to flight times, I flew for 9-1/2 minutes and my battery checker indicated 55% remaining. I’m charging the battery now, so I’ll see how much it actually takes.

I’ve got an 8x3.8 prop I may try, and I might also rob a lower kv motor off one of my other planes to try it out. I think this plane would fly well with a blue wonder, lighter plane allows lighter motor, less current draw allows smaller battery, the lightness just starts adding up. Or subtracting down, or whatever.

Just floated it in the hot tub, and the prop has a good inch and a half clearance to the water.

Never tried putting two props on one motor. Wouldn’t work with a prop saver but with maybe with a normal adapter. I have a 3 blade prop, 6-3 or maybe 6-4. I should try it...

Cheers,
Dave
May 12, 2020, 04:49 PM
Registered User
Battery just finished charging, took 552 mah. Well under half of a 1300. Looks like I could fly it almost 20 minutes if I wanted to.

I started with electrics in the early ‘80s, with big heavy can motors and nicad batteries. Back then it was a big deal for a sport plane to get a 4 or 5 minute flight. Now we have many times the performance, for less money, and we can fly long enough on a battery to get bored.

We’ve got it pretty good.

Cheers,
Dave
May 12, 2020, 05:59 PM
Registered User
dbacon's Avatar
Yes Electrics have matured. I had a Mirage 500 much like you said brushed can motor, NiCad, one of us knew how to get his motor to perform, but it wasn't me. I ended up putting a 40 or a 45 in the Mirage, and then I really loved it.

I tried to find this plane with a short search, but couldn't come up with it. It was a yellow high wing, tail dragger, maybe 46" span...
May 12, 2020, 07:46 PM
Light flies right!
dbacon, would it happen to be this? https://outerzone.co.uk/plan_details.asp?ID=9648

Nice looking plane!

Also, I really like the double prop idea. Been having some trouble with prop tip strikes on uneven ground, and I'm sure water flying would be problematic too, if I had I pond to fly from.
Last edited by Aer0naught; May 12, 2020 at 08:54 PM.
May 12, 2020, 11:51 PM
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dbacon's Avatar
Aer0naught,

Yes! That;s it! My search was 50 short of the real thing, Such perception, you have.

I have used the double prop configuration for a long time. On all my old IC "slimers" and recently on my electrics. With the electrics it was easy to see that my "X: prop was truly equivalent, because i could measure thrust RPM and Watts, Of course it is only static thrust, but what the heck.

I was after pulling power and not speed so it served me well.

Thanks for finding an old friend.
Last edited by dbacon; May 13, 2020 at 01:21 AM.
May 20, 2020, 08:19 AM
Registered User
Got a chance to try my latest Snowball off water. It flew fantastic! A bit over half throttle had it off the water in about 10 feet. Taxiing on step took well under half, once it got on a plane. It was super fun flying it close in, right off the end of the dock. I enjoy flying off water, but It can be nerve wracking with some planes. Not this one, totally relaxing and stress free.

Flew 10 minutes and used less than half a 1300 2s. Put in a 1000 2s (almost an ounce lighter) and flew another 9-1/2 minutes and still had 45% remaining. But by that time the black flies were starting to find me.

I’d call the water maiden a complete success. The foam I used is unaffected by the water, and with the 8” prop, not a drop of water got onto the top of the plane. I like it! It’ll be nice to have a flying toy for when we go to the lake this summer.

Cheers,
Dave
May 20, 2020, 08:45 AM
Registered User
dbacon's Avatar
I see a long antenna on the Tx, not the Rx ???

Glad to see the solid foam floats, but in my experience blue and pink and other foams slowly absorb water. Others have differed with me about this, but I carefully weighed these foams before and after immersion, and it was true!

So I built floats out of sheet Depron, and the plane (Capricorn) was lighter, but after many flights started veering over on takeoff.

I found the seams were leaking, so I opened the back of the float, and it drains immediately upon acceleration.

I will ask my friends about MPF to see if it is impervious to water, it has a lot of other major advantages too.


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