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Old Aug 29, 2010, 05:11 PM
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Ontario, Canada
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Originally Posted by ade h View Post
Mystery 12A Brushless Speed Controller (Blue Series)
Those Mystery Blue Series ESC's are re-branded models of another well known mfg. Although a bit older technology wise, they work very well. I have similar ones under a different brand name in 3 of my planes. If you buy one of these, let me know as I know if 2 different places to buy programming cards for them.
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Old Aug 29, 2010, 09:04 PM
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United States, WA, Olympia
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I am going to make a BB33 tonight. I couldn't find any small pieces of pink foam at Home Depot. I plan to use stacked EPP foam I have from shipping supplies for the monoblock and 6mm depron for the rest. Will I be able to bend the depron enough for the UC wing or should I make the Kfm3? Thanks
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Old Aug 30, 2010, 12:50 AM
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Might be able to roll or heat to bend the 6mm Depron for UC wing. It would slow down the best on landing, etc.

The KFm3 wing will be heavier, won't slow down as well.

Your choice? Both fly good, both have merits. I think one should build both!
Pick one, and go for it. Make the other one tomorrow...

Fred
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Old Aug 30, 2010, 08:48 AM
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Ive finished my BB33, and am wondering where the G.G is located? All help appreciated !
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Old Aug 30, 2010, 10:08 AM
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Originally Posted by FJK_12 View Post
Ive finished my BB33, and am wondering where the G.G is located? All help appreciated !
The CG on the BB33 with UC wing is 2.3" to 2.6" from the LE. The marks are shown on the BB33 World Plans:

http://www.rcgroups.com/forums/showa...mentid=1971823
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Old Aug 30, 2010, 05:57 PM
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Joined Jun 2007
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Trouble with my BB

Hi guys.
First, I want to thank Tony65x55 for the design. I've stall crashed it pretty hard three times already and it looks brand new.

I was super excited to finish my BB last night, so I took it outside for a quick taxi. I built a tail wheel in, and it drives just like one of my RC cars. I think I'm having more fun on the ground than I am in the air!
On the maiden flight today, it took off very smoothly from the ground but began to roll to the right in to some trees. I'm accustomed to just flying with elevators and ailerons, so I tried to roll out of the slow turn, but the ailerons did nothing! By then it had crashed, but no harm was done.
I gave up on the ailerons thinking that my control surfaces were two small. They are approximately 1.5" by 10", spaced closer to the center of the wing.
To make flying easier, I switched the rudder control with the aileron control so I would only have elevators and rudder on the right stick.
I flew it again, this time I trimmed my rudder to compensate for the roll. Things went smoothly until I tried to make my first turn. I pulled right on the rudder and the tail dropped, sending the plane in to a stall. I throttled up, but the stall stuck. It looked like some sort of fish flopping around in the air until I brought it down carefully on it's tail.
By this point I was stumped. I thought the CG might be too far back, causing it to stall like that. However, I tested the CG on the ground and found it to be about 2.5" back from the trailing edge, just what the plans called for.

Fully loaded, the plane weighs a feather over sixteen ounces. My current electronics setup is pretty static, so could I just add ballast somewhere?

Did anyone else have the same aileron issue on their BB? Looking at it now, I'm realizing that (since both ailerons are controlled by one servo) they have more travel going up than they do going down. Perhaps at the low speeds I was flying at, it was the down travel that I needed.
I just want to add that this a standard asymmetrical airfoil, the one called for in the plans. I'm tempted to try out one of those KFm airfoils though!

I'd post pics, but my camera is on the fritz.

UPDATE
I just tested it again with about an ounce of weight on the nose. That shifted the CG about .1" forwards Absolutely no change in performance.
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Old Aug 30, 2010, 07:03 PM
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SE MI
Joined Oct 2004
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Generally UC wings don't allow ailerons to work very well. When I added ailerons, I made a new kfm3 wing and she flys nice. I did have to achieve what I think you already have: lots of aileron differential- aileron going up travels much farther than aileron going down. That's good, as it compensates for and eliminates adverse yaw, where you try to roll to the right and tail goes right instead. I also put ailerons on right stick with elevator, rudder on left for 4ch, and rudder on right with elevator on 3 ch plane. That way, the actions are the same whether i'm flying rudder elevator with dihedral or aileron/elevator/rudder with a less dihedral plane. Flying 3ch with dihedral, the rudder actually works with the dihedral to bank the plane. How much dihedral do you have on the wing? Also, typically the ailerons run full span, just because it's easier than sticking them out on wing tips where they are most effective. If you have ailerons inboard, they may not be very effective.
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Old Aug 30, 2010, 09:02 PM
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Growf911

I agree, the ailerons going more up than down is good! Even as much as double (50% down). If you kept the stock 1 1/2 dihedral in the UC wing, probably too much for it to react correctly.

Make sure your wing is centered when mounting wit the rubber bands.

Try getting her up, and back way off the throttle, and see if it glides well, dead stick. Check to see if have right and down thrust built in.

When trimmed and landed, is your elevator set faily close to neutral? Or is it up and or down. At 16 ounces, did you build the 33" version, or larger?

Anything else you notice might help figure out where the trouble lies.

Fred
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Old Sep 01, 2010, 12:50 AM
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Quote:
Originally Posted by springer View Post
Generally UC wings don't allow ailerons to work very well. When I added ailerons, I made a new kfm3 wing and she flys nice. I did have to achieve what I think you already have: lots of aileron differential- aileron going up travels much farther than aileron going down. That's good, as it compensates for and eliminates adverse yaw, where you try to roll to the right and tail goes right instead. I also put ailerons on right stick with elevator, rudder on left for 4ch, and rudder on right with elevator on 3 ch plane. That way, the actions are the same whether i'm flying rudder elevator with dihedral or aileron/elevator/rudder with a less dihedral plane. Flying 3ch with dihedral, the rudder actually works with the dihedral to bank the plane. How much dihedral do you have on the wing? Also, typically the ailerons run full span, just because it's easier than sticking them out on wing tips where they are most effective. If you have ailerons inboard, they may not be very effective.
Quote:
Originally Posted by Freddie B View Post
Growf911

I agree, the ailerons going more up than down is good! Even as much as double (50% down). If you kept the stock 1 1/2 dihedral in the UC wing, probably too much for it to react correctly.

Make sure your wing is centered when mounting wit the rubber bands.

Try getting her up, and back way off the throttle, and see if it glides well, dead stick. Check to see if have right and down thrust built in.

When trimmed and landed, is your elevator set faily close to neutral? Or is it up and or down. At 16 ounces, did you build the 33" version, or larger?

Anything else you notice might help figure out where the trouble lies.

Fred
Thank you very much for your replies. Yes, my BB is a 33" with standard wing and 1.5" dihedral. I had no idea that dihedral could kill the effectiveness of ailerons. Looks like I'm going to have to build a KFm wing.

I flew the plane again today after adding more weight to the nose, but the problem persisted.

I was taxiing the plane back home (my driveway is ridiculously long) when it began to lift off. I didn't touch the power, keeping it low, and it flew like a charm. My absolutely stupid mistake was jacking the throttle all the way up after taking off. That, of course, sent the plane straight up. With about 1/4 to 1/3 throttle, it flew fantastically.

That was until I tree'd it.
There's a bit of a problem with wild grape vines in the woods around my house. There is a pretty thin, U shaped field that I fly from. In the middle of the U is a sort of peninsula of plane-killing undergrowth. Out of nowhere, this 40' tall cherry tree grabbed my blu baby! Even worse, the grape vines made a mess of the landing gear and would not let go even after an aggressive prodding with the longest pole I could find.
Long story short, I borrowed a neighbor's pole pruner and orchard ladder so I could nip the vines out of the way. Down fell the baby, lipo and all. The damage wasn't too bad. I lost the prop and I gained a few dings after trying to get it down with a pole, but the Blu Baby lives to fly another day!

Things actually turned out pretty well. My uncle lives nearby, and when he saw me halfway up the tree, he was prompted to bring out some old model plane stuff that he and his brothers had at my age. He left me with three large boxes of shoddy balsa, an ancient control line stuka, and an enormous gasser with no radio controls! They just threw the thing and expected it to come down safely! I'll dig through the boxes in detail tomorrow.

Thanks again, RCgroupers! << isn't that a kind of fish?
you have never let me down!
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Old Sep 01, 2010, 05:24 AM
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Ontario, Canada
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Originally Posted by Growf911 View Post
Thank you very much for your replies. Yes, my BB is a 33" with standard wing and 1.5" dihedral. I had no idea that dihedral could kill the effectiveness of ailerons. Looks like I'm going to have to build a KFm wing.
The dihedral is not the issue. It's because you are using an undercambered wing.

I have a BB33 with a KFM3 wing and 1" dihedral per side. It flies very nice with ailerons.
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Old Sep 01, 2010, 10:49 AM
If it flies, I will crash it
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USA, CO, Westminster
Joined Jan 2008
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Yep, there have been people that have done it but they are not very effective. You are on the right track on building the KFm wing. They work rather well and you should not be disappointed.

Rob...
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Old Sep 01, 2010, 12:36 PM
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True, clear this up. Excessive dihedral and undercambered wing equal to little or some adverse reactions when installing ailerons. We will call excessive dihedral, that amount of dihedral needed to fly rudder/elevator only.

The KFm3 wing, or any flat plate, or traditional cambered wing (KFmXX included) will work much better using ailerons, but dihedral still needs to be less than on an rudder/elevator only design.

My KFm3 wing has 2 degrees per side, 4 degree total dihedral, compared to 10 degree on the R/E version. I could use no dihedral and improve rolling manuvers, but decided to keep some self righting stability in this planes wing.

Fred
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Old Sep 01, 2010, 05:16 PM
If it flies, I will crash it
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USA, CO, Westminster
Joined Jan 2008
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The issue with ailerons and the 4040 under camber wing has less to do with dihedral angle and more to do with how the wing creates lift and what the aileron surface does to that lift. In most cases ailerons aren't to terribly effective on UC wings. That being said there are cases of people getting them to work.

The dihedral angle issue is less refined and has more factors involved but basically, yes, a wing with ailerons will have less overall dihedral then one without. I have added ailerons to a KFm3 profile wing and it worked but required considerable differential. Eventually I cut the wing apart and took out some dihedral.

So your on it,
Rob...
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Old Sep 01, 2010, 06:33 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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With the ease of wing swaps on the BB's I'd encourage anyone who has mastered the RET setup with a wing with dihedral and is interested in trying ailerons and more spirited flying to consider building a flat (no dihedral) KFm3 wing with ailerons on it.

That produces a plane that requires a little more attention to fly but it is not very much. And if you want to start sampling the "fly it like a real airplane" experience it will be very entertaining.

The BB's with their high wing have fairly good inherent stability with a flat wing. I think it is because of the sort of pendulum effect of the cabin hanging below the wing and maybe the mass in the cabin (battery, etc.) helps with that.

You'll find the plane needs a little more attention while you fly but not a lot more. Once it is trimmed it will settle out to level from a gentle aileron turn if you give a little time. But you'll quickly start developing the instincts to fly the plane into and out of turn more and that is a good thing.

I had to remind myself about the rudder over on the throttle stick a little at first but as soon as I used it a little it became a pretty subconscious thing too. You'll quickly learn that using a little rudder along with the aileron produces a much prettier turn. And it does other wonderful things like increasing the turn rate, correcting a lineup without dropping a wing, making flat sweeping turns when you have a camera on board, and other things like that.

And if you want to crank in a little more throttle and start playing with aerobatics, use of both rudder and ailerons is an essential component of that and a flat winged BB 33 will do a surprisingly good job at beginning aerobatics.

Jack
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Old Sep 01, 2010, 08:47 PM
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I always have troublr with R/R/T planes because when I try to take off, I forget the rudder isn't on the throttle stick because I'm too used to 4 chanel R/E/A/T setups!

BB flys so good on 3 channel it's almost a shame to set it up different, call me nostalgic or something..... But my 4 channel BB with night flying nav lights is ready for a good day, or is that evening.....

Fred
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