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Old Jun 08, 2015, 06:41 PM
jackerbes is offline
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Jack
USA, ME, Ellsworth
Joined May 2008
18,033 Posts
No insult was intended, I was trying to make the point that the inherent stability of the design is pretty well proven by this thread.

And when I say "builder" I am referring to the person that built it and prepped it for flight and made the flight you describe.

And, as I said back on page 1300, that was a very nice build!

But something was obviously not right if it was always unstable on the roll axis and I don't think that is a design fault.

I don't see anything obvious in the images you posted and you had a well proven and much used power system with the often used Silver Wonder class motor.

If the CG was about right (2.3" to 2.6" back from the leading edge) and there was no great lateral imbalance (no "heavy" wing to either side) I would expect that plane would have floated out of your son's hand and into levelflight with a gentle level push and about 1/4th to 1/3rd throttle.

Sorry it did not go better for you...

Jack
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Old Jun 09, 2015, 04:22 AM
Yachtie04 is offline
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Joined Jun 2014
154 Posts
No offence at all taken Jackerbes. :-)
Yes - I was the builder and one who installed the electronics etc.

In calm air the plane would fly normally straight and level, but if it encountered a bit of light turbulence the plane would suddenly roll maybe 30 or 40 degrees either way and take some time to right itself fully.

Even small amounts of rudder would make it roll a lot quickly - yet I had the pushrod on inner hole of servo arm and outer hole of rudder horn (minimum throws).
I really don't know or understand why it behaved that way.
It doesn't make any sense to me.

Longitudinal pitch was fine and stable - just rolling was a problem.
The 32 inch span BYOB by comparison is very stable only rolling a few degrees with the same turbulence and then quickly righting itself. In fact considering it's very low wing loading it is exceptionally stable.

My only suspicion is that maybe I had the vertical centre of gravity too low causing pendulum effect which over-rode the natural righting moment of the wing dihedral.
My undercarriage wire was a bit heavier than shown on the plans and also a bit longer.
It is a pity it crashed before I got a flight with the battery mounted higher - so will never know if that had any effect on the rolling.

I have just too many other planes on the go at present that I am not prepared to spend time rebuilding the plane and doing further flights.
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Old Jun 09, 2015, 05:46 AM
jackerbes is offline
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Jack
USA, ME, Ellsworth
Joined May 2008
18,033 Posts
Just to show you how I got started, here is my first BB 33 build. It had less than 30 seconds of flight it at that point.

I was a pretty new pilot and started with a KFm3 wing with low dihedral and ailerons. And probably was not ready for it. I patched that up with some side plates but it did not last much longer. I quickly moved on to wider monobloc version and started "building to crash" with what I called my BBIS or Industrial Strength Blue Baby builds. Those had a CF arrow shaft embedded in the monobloc and it extended back to tail so I broke no more fuselages.

Certainly have no regrets about the time spent on the BB's, still have one this is flyable and several wings but have not flown it lately.

Jack
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Old Jun 09, 2015, 06:38 PM
Yachtie04 is offline
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Joined Jun 2014
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I have to agree with you that if I ever built another Blue Baby I would use CF reinforcing in the fuselage.
I had a crash earlier and broke the fuselage off ahead of the tailplane.
I was ably to glue everything back together and get her flying again - but this last crash did a lot more damage.
I can salvage the U/C, radio gear and servos, pushrods etc for another plane later perhaps - but with so many planes to complete and fly it may be quite a while.
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Old Jun 09, 2015, 09:15 PM
jackerbes is offline
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Jack
USA, ME, Ellsworth
Joined May 2008
18,033 Posts
As most of us went to the 2" wide monoblocs it really helped on the fuselage strength. And I made longer monoblocs and tapered them to tail too. And when I drilled a hole down them with a tube drill and put a CF arrow shaft in there with foamed up PU glue, that was my BBIS build!

Good luck with it, there are so many good planes for us guys that like to build and so little time...

Jack
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Old Jun 20, 2015, 11:20 AM
tarcher3d is offline
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Canada, ON, Port Perry
Joined Mar 2015
2 Posts
Hello all
I am currently building a BB42 with $tree foam & kfm3 wing with ailerons. Getting back into the hobby and need something for my front yard (3 acres).

Just want to send out a big thanks to Don at strongarm rc, ordered 2 dsm2 receivers last sunday got them Thursday

I know!!! Will post pics when done

Tom
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Old Jul 15, 2015, 09:50 AM
lanre is offline
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See me! I dey fly!
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Yenago, Bayelsa State, Nigeria
Joined Jul 2004
46 Posts
Wow! Been out of the building game for a very long while. See how long has grown!
Me need to get me a new BB32!
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