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Nov 16, 2010, 01:32 AM
Mark Harrison
Originally Posted by Bob A
Is there a guide somewhere that explains the different electrical connectors? I have ordered components to build my BB from 2 different sources and have no idea whether components will connect or not.


I've also suffered though connector issues as I've been getting started. Here's some notes I made that might be useful to you:

Last edited by marhar; Jan 31, 2011 at 09:33 PM.
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Nov 16, 2010, 03:00 AM
Registered User
Tommee's Avatar
Originally Posted by Wilfor
Tommee Good to see your still working away at it . You havent posted in a while and i thought maybe we lost you . You build looks nice and clean is you foam hand cut ?? I dont get nice clean lines like that by hand . Keep the pictures coming there alway nice to see . Now to go have a Pivo or 2
Hi Wilfor

No, I'm here all the time but I was waiting for some parts (wanted everything double so my girlfriend can build one BB too) and at the same time trying to balance between motorcycle, Split, new iPhone 4 and other time consuming activities

Yes, foam is hand cut with xacto knife guided with plastic ruler, nothing fancy. When I get picky than I start to sand everything to get clean lines.

Of course, pivo or two can help to get those true straight lines
Nov 16, 2010, 06:14 PM
Registered User
Thanks tony! This plane is going to be my first solo build. Just started cutting out the parts from redifoam and I hope to have her flying over the weekend.
Nov 17, 2010, 01:44 AM
Registered User
Hi Folks, well I did it, I jumped in and built one of these planes over the last week or so. Thanks to all the info in this thread (and Tony of course) I finally got it finished. I went down to the local park to test fly it today. I started off across the paved parking lot and it started drifting left, a little right rudder and nothing happened, a little more right and the plane spun around 180 degrees. Tried again and same thing. I tried a dozen more times and no matter which way it drifted, I could not correct it without it spinning around. Needless to say I did not get up enough speed to takeoff! Ok, so next I got my friend to hand launch it, a gentle toss, 3/4 throttle and away she goes! holy crap its flying! Did a gentle turn to the left and Straightened up, lowered throttle and landed it on the pavement! What a rush that was! Flew a couple more times before I had to call it quits. Very cool to see something that you put together actually flying. I have not flown a fixed wing before but I have been flying my Blade 400 heli for about a year. I have a few hours of Realflight sim time with fixed wings.

Now the questions start! What would cause the twichiness(for lack of a better word) on the ground? Would larger wheels help? (mine are 1" foamies)
Could my landing gear wire be to thin? I believe its .062 piano wire.

How do you check the CG? I understand that it should be 2.3-2.6" from the LE of the wing. Is it acceptable to place a finger underneath the wing on both sides at the CG point and check for balance?

I noticed that on the plan of the fuselage side, there are 3 holes, 2 for the wing mount skewers and a third. Is this the CG point? If so its only about 1 3/4" from the LE. I did a test and stuck a skewer in each side of the fuselage at the third hole and my plane balances pretty close. What's the correct way to do this?

Thanks again Tony and everybody else!

Here is a couple of pictures of my plane. Just ignore the paint job, I just needed something bright and easy to see.

Regards, Nick.

Nov 17, 2010, 07:40 AM
Eagle34's Avatar
One thing I noticed is you landing gear are kinda splayed out giving the wheels a negative camber. This will only worsen as the weight of landing will want to splay the wheels out more. Negative camber has the effect of a higher steering effort, as you have already learned. Most full size planes, (cropdusters, bush planes, ect.) use a bit of positive camber (the top of the wheel will lean toward the fuselage) to give a lower steering effort as they are mostly used from unimproved runways, and also the landing forces will tend to push the wheels out.

Try bending your gear so that the wheels are straight up and down or slightly tilted toward the fuselage at the top of the wheel. Also you might want to remove the wheels and lay the plane on a flat surface (hanging vertically by the landing gear) like the edge of a table. Check to see that the axle stubs (the horizontal part of the gear in normal configuration) are perfectly flat on the table. If not you either have toe in or toe out. You want a little toe in to discourage the initiation of a turn, a little toe out will encourage the initiation of a turn. A little toe in is better again due to the landing forces wanting to push the wheels rearward. Either way you want both left and right as even as possible.

I don't think its twitchiness that you are experiencing, more like slugginess, until the forces on the rudder overtake. Twichy would be right rudder, left rudder, right rudder, left rudder. Sluggy (as you described) would be right rudder, more right rudder, more right rudder, OMG spin out. Larger wheels might help you out some also. I think Im using 30 or 35 mm on mine.

Your build looks very good though. What motor are you using? It looks big. What is the wing span you built? Hard to tell from the pictures as they all look a like.
Nov 17, 2010, 08:22 AM
Registered User
philipa_240sx's Avatar
Originally Posted by stelni
I started off across the paved parking lot and it started drifting left, a little right rudder and nothing happened, a little more right and the plane spun around 180 degrees.
Ah yes, ground looping at it's best! Even I still manage to do it from time to time.

The tips Eagle34 gave will help. A few more idas:

- Not something I recommend until you have more experience: Don't mess around on takeoff... WOT until she's airborne than back off the throttle slightly so she won't stall. You spend less time on the ground and less chance or ground looping.

- Try bigger wheels (1.5-2"). The small diameter isn't helping you as it produces a very tight turn as the wheel camber changes under load.
Nov 17, 2010, 11:06 AM
Registered User
Thanks for the info guys. I will straighten up my gear and try some larger wheels. Its wet and windy here today so probably won't get a chance to try it for a couple of days, but we will see.

Some more info on my build: Its a 33" UC built according to the plans except I used a 2" wide monoblock. The motor is an Eflite park450 960kv that I had lying around, with a 9X6 prop and 2 cell li-po.

It does not seem overpowered by any means, in fact I was thinking of trying a 3 cell pack. The limited flying I have done has been pretty much at wot most of the time, and it flys fairly slow and gentle, and seems very responsive to stick movements. My concern is no reserve power to get out of trouble (or maybe this would get me in trouble!)

Roughly where should the throttle be for level flight, 50% or so?

Nov 17, 2010, 11:33 AM
Eagle34's Avatar
WOW that combination should push your BB33 around pretty good, even on a 2S battery. Only thing I can think of is you may be a bit heavy. What's your AUW?

My BB24 with the HK 10gr motor, 450 2S battery and 5X4.3 will fly nicely at around 50% throttle, maybe a bit more. I definately don't need WOT though. My AUW is about 135gr. It's nice to have that reserve power just in case you find yourself in a bad situation, or to be able to fly in a little higher winds.
Nov 17, 2010, 12:01 PM
Registered User
Well its definitely heavy, auw with 2 cell is 445g (15.6oz) Its built from Elmers foam board from Michaels which has a thick paper covering on both sides. Tried removing paper but its not an easy task. I found some rediboard at the dollar store that is half the weight, and the paper is much thinner and easy to remove. The wing is made from the lighter rediboard (paper removed so I could bend it easier) with carbon le and te.

Nov 17, 2010, 12:18 PM
springer's Avatar
Stelni: lots of good info already, but I'd chime in on bigger wheels help, and it's pretty common for a tail dragger to do the ground loop thing, Easier to do than to avoid in my experience. As Phillipa noted wot or at least 3/4 throttle on take off will get most BB's airborne in a few (like 2-3)feet. Do the hand launches for a while to get the feel of her, then try that after making sure your Landing gear is oriented right. definitely toe in, and you may want to double up the wire on the down strut portion - wrap with string and epoxy or wrap with thin copper wire and solder to retain. I'm at library, so can't do a good sketch, but here's a powerpoint pic that may explain it.

The motor is pretty low KV, so won't fly her fast (I like at least 1700kv for a 33" bb size), so I'd go with a larger prop or higher pitch, I think you can get a 9x7.5 sf. as long as you're using 2s,

definitely heavier than typical too, a 33 should be more like 10oz with gear. Should be a goo windy day flyer tho! At that weight I'd stay with 2s and go for more thrust - larger prop and/or more pitch.
Nov 17, 2010, 07:01 PM
RC Adddict
Wilfor's Avatar
The third Dowel you speak of is for battery retention
Nov 17, 2010, 07:37 PM
Registered User
Originally Posted by Wilfor
The third Dowel you speak of is for battery retention

Now that makes sense! Funny how you can overlook the obvious eh!
Maybe because I used a velcro strap to hold my batt in I never gave it much thought.

Thanks Wilfor.

Nov 17, 2010, 07:39 PM
Registered User
wheelspinner20's Avatar
Tomee, No way I was "picking on you " (I know jack doesnt mean it in a bad way) No in fact That is a very clean cut plane. And your right, different fro EPS style foam. And I'm glad to hear that the prop clearance thing is just some trim and fit issue.

Griff, Nice on the maiden, it was my 3rd or 4th flight when i clipped a tiki torch of all things. Cartwheeled onto the deck, striking and breaking the horz. stab!! Although I must confess, I should NOT have been attempting to fly where I was. I got cocky and over confident (you would'nt believe me if I told you so I won't)

Philipa was right, just build... fly... (repair if your new) and have fun....

Which brings me to Stelni, What a rush indeed. Isn't it strange how good it feels?? I built it, and it flys. Nice job too, looks good. Yes, the tail spins around very easy. well, in my case, its only when i am trying to taxi, not taking off, it doesnt have time to spin around on take of because it only takes about 24 inches. Blue wonder motor on 2s with a 9x4.7sf. But yes, its tough to taxi, especially with any breeze. Wants to spin. Even a very experienced flyer, when he didnt touch and go, like when he is coming down to stay down, it spins on him, he just laughs.!

Gotta go, cutting more BB's and a kfm3 wing.!

Nov 17, 2010, 08:09 PM
My tail dragger will all ground loop....unless I hold full up elevator (to keep the tail solidly dragging) untill almost up to flying speed. Then reduce the up elevator and let it take off. So here is the plan: full up elevator, increase throttle untill it starts to move, as it gathers speed, release elevator toward neutral....it normally lifts of in way less than 15'. If I go to near full throttle it will be airborn and climing too steep with in 2-3 feet. Then you need to get to some down elevator or your going to air loop it, or stall if you reduce power. Full up elevator before increasing throttle is the key to starting off with a straight takeoff run.
Nov 18, 2010, 11:59 PM
Registered User
OK I have re bent my lg and made a couple of 2" foamy wheels. May have gone a little overboard on the positive camber and toe-in but I will try it before I change it. Now I just need some dry weather to go and test it!

Any one ever make skis for their baby? Looks like we may get some snow this weekend. I was thinking something simple like a piece of foam curved at the front with a plywood rib glued along it, any ideas?

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