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Old Nov 24, 2012, 11:25 AM
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Crash&Bounce's Avatar
Nevada, USA
Joined Jun 2004
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Quote:
Originally Posted by goldguy View Post
Crash&Bounce:

I realize yours is not symmetrical being a KF airfoil, but all airfoils need positive incidence to create lift, even a KF with the step on the top, bottom or both.

A tall rudder is more effective than a wide one in designs that use a rudder and dihedral to turn. So, cut it down and re-set the motor's down thrust after a study of the plan as posted back in the beginning. Following the plan will guarantee success and that's no mistake.

Frank,
Now I'm insulted. If you read my post, you would know that I did build it to the plan. I've been tweaking the downthrust literally for months, and no one was more surprised than i was to measure it out at 13+ degrees. I arrived at this one washer at a time, over many flights.

I wasn't expecting it to be twitchy at all. Nothing I read in the thousands of posts suggested that it might be. Some folks even suggested that it was a good beginner plane. I even avoided other "flying saucer" designs in favor of this one because of it's alleged stability.

I'm sorry if these posts sound like sour grapes. I am trying to salvage something from this build, and it's been extremely frustrating trying to get it to fly for more than a couple minutes at times.
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Old Nov 24, 2012, 12:58 PM
┌∩┐(⋟﹏⋞)┌∩┐ The FAA
nightfox7's Avatar
United States, GA, Cornelia
Joined Jan 2012
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Don't get onto frank, he's trying to help you out here. Either take his advice or move on.


Now, a few words from a newbie.(me) I've been flying for about 8 months. I built a nutball the first month I started flying, to go along with my first plane so I could fly it in my front yard. (Which is not very big) and I had an absolute blast with it. It few beautifully, and I didn't even have any down thrust or right thrust.(in fact, I didn't even know what that meant at the time) all I did was follow the plans. And yes I know you said you did too.

So my suggestions: increase your polyhedral, because from your pictures it looks like there isn't much, I think I had at least 2 1/2" on each side. (I would check for you, but my nutball is in nut ball heaven, it had a glorious meeting with the earth while doing the nutball "whompa whompa whompa". It was repairable but I decided to decommission it)

Or even better: just start over. It takes what, 15 mins to cut out the stuff?

If the above does not appeal to you, either get more stick time (you aren't the only one that needs this), or find another plane.

What is your flying experience? What have you flown before? Your flying style might not meld with the style that the NB needs, as everyone has said, its your throttle management.
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Old Nov 24, 2012, 02:44 PM
chuck
santa barbara, CA
Joined May 2009
3,957 Posts
well said, and i noticed the lack of dihedral also, but it is kinda hard to see for sure.
a airframe can be both stable and responsive ,and the n/b is, so again if it's to twitchy , turn down the travels.

chuck
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Old Nov 24, 2012, 03:16 PM
Registered User
United States, OR, Eugene
Joined Sep 2009
136 Posts
C&B,

I thought, too, that from your photos it looked like the dihedral was a little flat. I would:

1. Increase the dihedral
2. Build the vertical stab/rudder exactly to plans (from the picture your rudder looks a little narrow and too tall.)
3. Decrease the control throws until you're proficient at flying the NB.
4. Not expect it to fly like a pattern ship, nor glide like a sailplane. The "20 degree nose down glide" you described I think is typical for this plane, and a lot flatter than either of mine have been. As everyone says, use minimal throttle for "level" flying, which is usually at a much higher angle of attack than conventional planes. If you trim the elevator for "level" slow, low-throttle flight, it will always climb at full throttle.

5. Remember that _you asked_ for help after reading all 500 pages of people praising this design. Countless people have been having tons of fun and success with the NB and you can too, especially if you accept with a good attitude the help offered.

Don
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Old Nov 24, 2012, 04:12 PM
flyin' fool
goldguy's Avatar
Vancouver Island, Canada
Joined Jul 2003
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Quote:
Originally Posted by Crash&Bounce View Post
Frank, Now I'm insulted.
My advice to you was just that, advice and not meant to be insulting. I'm sorry you took it the wrong way.

You implied that building the NB was a big mistake and I was implying that from the look of yours, the height of the rudder is all wrong 'according to the plan'. As far as the motor's down thrust on yours goes, that much tells me there are other problems to sort out with your build.

I know if you get yours all sorted out, then you'll have loads of fun with it. I wouldn't like to see you give up and miss out on all the silly fun.
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Old Nov 24, 2012, 04:21 PM
flyin' fool
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Vancouver Island, Canada
Joined Jul 2003
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Another point to consider.................the amount of dihedral and the height of the rudder have to be tuned into each other. If you have more of one, then you need less of the other.

A too tall rudder will cause an overactive input and so will too much dihedral. The original design took this into consideration and has since been modified as guys got tuned into how it flew and wanted it tuned into how they liked to fly it.

The first rules of fine tuning a NB is low throttle and small inputs on the control surfaces. Once you get it sorted, then you can toss it around in an extreme fashion with 45 degrees of throw each way and always come out smiling.
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Old Nov 24, 2012, 04:38 PM
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Joined Sep 2011
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first , hello to all rc guys , can you tell me , how do i determinate the cg on a 19 inch , and 20 nutball , im a noobie , and i have started with the bluebaby , but now want to try to have a go on this one , it looks cool and fun . im in the uk and im from portugal , so excuse me for my bad writing . cheers .
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Old Nov 24, 2012, 04:45 PM
chuck
santa barbara, CA
Joined May 2009
3,957 Posts
25 % of the over all diameter from the nose to start.
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Old Nov 24, 2012, 06:13 PM
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Joined Sep 2011
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thanks , im gonna do a depron one , all electronics are around 4 1/4 oz with battery 3 ceel 1200 kv brushless and 9 gram servos , should i build the 20 inch with this specs , or the 17 ? the prop should be an 8x4 .
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Old Nov 24, 2012, 06:25 PM
chuck
santa barbara, CA
Joined May 2009
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need to know more on motor weight, battery size ect. but most likely go bigger.
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Old Nov 24, 2012, 06:40 PM
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motor is 16 grams , 500mha 3 cell , 18amp esc , sorry motor is 1200kv . thanks for your help .
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Old Nov 24, 2012, 07:11 PM
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Philippines, NCR, Manila
Joined Nov 2012
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Nb

Quote:
Originally Posted by goldguy View Post
I only speak English, but your first verbal expressions are truly universal. D

Frank

Yes my friend ask me what is the meaning of that NB its a nutball or you can call it NEWBIE because im a newbie it flies me like a PRO....to those who are not happy with there NB just stop salvaging this NEWBIE plane....
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Old Nov 24, 2012, 07:26 PM
chuck
santa barbara, CA
Joined May 2009
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Quote:
Originally Posted by aviao View Post
motor is 16 grams , 500mha 3 cell , 18amp esc , sorry motor is 1200kv . thanks for your help .
well from that info i think u could go either way , the motor is ideal for the 17 , the battery more for the 20. a 20 will be more on the slow and floaty side , the 17 faster and more wild. if u went 17 u could always go down in battery size to get it lighter.
the 9 gram servos are not needed on the 17 and would be better suited to the 20.

have i confused u enough?

chuck.
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Old Nov 24, 2012, 08:49 PM
flyin' fool
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Vancouver Island, Canada
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Build a 18 1/2" span then.

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Old Nov 24, 2012, 08:50 PM
flyin' fool
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Vancouver Island, Canada
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No, I really mean it.
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