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Old Jan 05, 2013, 06:44 PM
Slipping the Surly Bonds
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Attica, MI
Joined Dec 2006
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Hi Moray,
The 2213 would do well for the 42. The 2826 is a bit weighty of a setup for the 33.

Sorry,
Ken
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Old Jan 05, 2013, 07:18 PM
Raikkonen for President
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United States, FL, Davenport
Joined May 2012
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Quote:
Originally Posted by Freddie B View Post
I have built multiple BB 33's over the last 3 years or so. Also been scratch building and flying most of my life (about 50 years????)

If you give your BB some extreme 20-30 degree throws, it can be twitchy, especially since it is Short Coupled, AND has a shotr wingspan. But I like mine that way. Short coupled, and a short and wide wingspan is all an important part of the design, and thousands of users have had so much fun and success with it.

I can snap roll mine with rudder/elevator only. It happens so fast and in about 2 or 3 airplane lengths of flight doing it! But with the high wing, the pendulum effect when self righting is a definite "twitchy' recovery. Turn up your control throws and experiance a lot more fun! Watch adding floats if you do because when it self rights out of a sharp banking turn, it will swing the undercarriage the opposite direction coming out of the turn!

Any short coupled airplane witll fly a bit more tame with a longer moment, and often a longer and thinner wing is recommended. You could also shrink the tail section sizes, but then we start to come up with a complete re-design. Keep it simple, but nothing is hurt by some small adjustments.

Fred
My Kfm3 33" blu baby snap rolls in a heartbeat and rolls like a drill with full width ailerons. Short coupling means it banks like crazy with rudder. Loops are possible at 1/3 throttle with 1700kv blue wonder on 3s. My throws are large, close to 45 degrees everywhere except ailerons which I set up differential on via my Dx8. But - let off the controls it doesn't right itself because of no dihedral but it absolutely STOPS flopping around the sky. For what it is it's ridiculously aerobatic. It's a great plane, I love it.
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Old Jan 05, 2013, 07:46 PM
Addicted to building...
Freddie B's Avatar
Omaha Nebraska
Joined Feb 2006
5,992 Posts
Quote:
Originally Posted by bhoov128 View Post
My Kfm3 33" blu baby snap rolls in a heartbeat and rolls like a drill with full width ailerons. Short coupling means it banks like crazy with rudder. Loops are possible at 1/3 throttle with 1700kv blue wonder on 3s. My throws are large, close to 45 degrees everywhere except ailerons which I set up differential on via my Dx8. But - let off the controls it doesn't right itself because of no dihedral but it absolutely STOPS flopping around the sky. For what it is it's ridiculously aerobatic. It's a great plane, I love it.
Now we're talking! Tons of fun from one simple little foamie aircraft design.

Fred
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Old Jan 15, 2013, 10:25 AM
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Joined Jan 2013
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what are the internal parts for this thanks ie the motor and how many servos it has

can some 1 plz give me a list of things i need thank you very much
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Old Jan 15, 2013, 12:30 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by daza1895 View Post
what are the internal parts for this thanks ie the motor and how many servos it has

can some 1 plz give me a list of things i need thank you very much
For a typical BB 33, right? Is that what you are asking?

These will work, as will anything like them:

motor (1) - http://www.headsuprc.com/servlet/the...trunner/Detail

ESC (1) - http://www.headsuprc.com/servlet/the...-10-Amp/Detail

battery (1) - http://www.headsuprc.com/servlet/the...mah-35C/Detail

prop - GWS 8043 slow fly prop - http://www.headsuprc.com/servlet/the...ler-ONE/Detail

9 gram servos (2 to 4) - http://www.headsuprc.com/servlet/the...9g-SG90/Detail

Two servos for RET and 3 or 4 to add ailerons also.

Jack
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Old Jan 30, 2013, 11:34 AM
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United Arab Emirates, Ajmān, Ajman
Joined Jan 2010
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Hello Guys, I'm totally a beginner and this is my first RC plane, I'm about to go for my maiden flight soon and would like to verify I made the right combination for my baby

Wing: 42" KFM3 2" dihedral
AUW : 580 gms
Motor: eflite 370 1200kv
Prop: APC 7x4
ESC: Hobbyking SS Series 15-18A
Battery: Zippy Compact 850mah,3S1P, 35C

The plane is tail heavy but I'm still trying to balance (so far it balances after adding dummy 25 gms after the motor!).

What do you think?
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Old Jan 30, 2013, 02:41 PM
treefinder
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SE MI
Joined Oct 2004
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Not familiar with the eflite motor, but if it's about a 40gm motor at 1200kv then you are in the ballpark, but the 7x4 prop sounds a bit small, the smallest I use on my 42" span BB is an 8x6, and more usually go to a 9". It'll fly with a lot bigger battery too, of course. depending on where you put the pack, that may help your balance as well.
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Old Jan 30, 2013, 02:56 PM
Raikkonen for President
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United States, FL, Davenport
Joined May 2012
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I found a 7x4 to be sluggish on my 33" blu baby, using blue wonder 1700kv. I suggest a bigger prop as well.
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Old Jan 30, 2013, 03:50 PM
The earth sucks! Thankfully.
Joined Jun 2003
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Quote:
Originally Posted by andalosy View Post
Hello Guys, I'm totally a beginner and this is my first RC plane, I'm about to go for my maiden flight soon and would like to verify I made the right combination for my baby

Wing: 42" KFM3 2" dihedral
AUW : 580 gms
Motor: eflite 370 1200kv
Prop: APC 7x4
ESC: Hobbyking SS Series 15-18A
Battery: Zippy Compact 850mah,3S1P, 35C

The plane is tail heavy but I'm still trying to balance (so far it balances after adding dummy 25 gms after the motor!).

What do you think?
andalosy:

One of the most common causes of crashed RC airplanes is the center of gravity, CG, not being properly placed. The weight you're adding is anoying but important.
Most importantly, make sure the CG is NOT AFT (rear of) of the recommended 3.44 inches (87mm) from the leading edge of the wing just next to the fuselage shown in the Blu Baby 42 inch KFm3 World Plan.pdf in post #107

In post #10600 and post #10601 are pictures of handy CG balancers.

- Jim
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Last edited by JimHSoars; Jan 30, 2013 at 04:12 PM. Reason: Clarification
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Old Jan 30, 2013, 05:49 PM
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United States, FL, Sunrise
Joined Jul 2011
194 Posts
Quote:
Originally Posted by springer View Post
Not familiar with the eflite motor, but if it's about a 40gm motor at 1200kv then you are in the ballpark, but the 7x4 prop sounds a bit small, the smallest I use on my 42" span BB is an 8x6, and more usually go to a 9". It'll fly with a lot bigger battery too, of course. depending on where you put the pack, that may help your balance as well.
I use a 370 park motor on my 42", with a 10" prop. I maidened with a 9" and 3s 800marh battery. Which flew well, but the 10 is better and I prefer using 3s 1300mah batteries as well. It allows better penetration in wind, bigger might still be better, but that's all I have. As noted by others make sure you get your C.G. right and mark where your battery is placed so you don't accidentally change it when you change/charge your batteries.
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Old Jan 31, 2013, 07:51 AM
Registered User
United Arab Emirates, Ajmān, Ajman
Joined Jan 2010
31 Posts
Thank to you all for this great advice, I bought today Great Planes CG machine, 9x4 Prop, and eflite 1350 mAh battery.

I balanced the plane at last after moving the new battery a little bit forward and vola everything seems OK. I attached the result.

Going to make the final power test for all the components.

Thanks again for all your support
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Old Jan 31, 2013, 08:30 AM
treefinder
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SE MI
Joined Oct 2004
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Looks good, I think you're gonna like her! (I was gonna comment to not forget to consider skis and floats in addition to wheels for future activities with your new plane, before I noticed where you're located! - maybe floats if you're close to the ocean, but I doubt you'll need skis)
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Old Jan 31, 2013, 09:05 AM
Registered User
United Arab Emirates, Ajmān, Ajman
Joined Jan 2010
31 Posts
Quote:
Originally Posted by springer View Post
Looks good, I think you're gonna like her! (I was gonna comment to not forget to consider skis and floats in addition to wheels for future activities with your new plane, before I noticed where you're located! - maybe floats if you're close to the ocean, but I doubt you'll need skis)
Well, I didn't find floats suitable for soft sands on rcgroups so far
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Old Jan 31, 2013, 02:46 PM
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United Arab Emirates, Ajmān, Ajman
Joined Jan 2010
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Quote:
Originally Posted by sixfins View Post
I use a 370 park motor on my 42", with a 10" prop. I maidened with a 9" and 3s 800marh battery. Which flew well, but the 10 is better and I prefer using 3s 1300mah batteries as well. It allows better penetration in wind, bigger might still be better, but that's all I have. As noted by others make sure you get your C.G. right and mark where your battery is placed so you don't accidentally change it when you change/charge your batteries.
Hi sixfins,

I just finished testing the park 370 with a 9x4 prop and it seems beyond the motor capability (Watt meter reads 11 amp at 85-90% throttle!). Would you please give more details about the type and pitch of the propeller you used?

Thanks.
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Old Jan 31, 2013, 03:31 PM
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United States, FL, Sunrise
Joined Jul 2011
194 Posts
I think it was a 9x6, can't really remember. What I use now are 10x4.7 and 10x6. I think they are GWS props, not sure. They're the cheapest ones at my LHS only $1 each. Really I only use about half throttle most of the time. With full throttle I have unlimited vertical and can take of with only a few inch roll out if any (well under 1'). With half throttle I can do loops and rolls, fly inverted and land after 8-10 minutes. The motor is always cool, not even warm, the esc and battery get warm, but not hot (about 95-97).
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