** Blu-Baby Primary Trainer ** Plans, Pics and Fun! - Page 1075 - RC Groups
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Dec 22, 2010, 07:47 AM
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Tommee's Avatar
Originally Posted by ruff1
Just a narration by Don LaFontaine would have made it complete!
You gave me great idea!

I forgot that
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Dec 22, 2010, 08:53 AM
wheelzup's Avatar
Tommee... Croatia my foot.... you're all Hollywood. You're right, the soundtrack really contributes to the self-important feeling.
So, any footage of a BB breaking through a cloud deck, rising up and disappearing into a halo of sunlight low on the horizon...
Dec 22, 2010, 09:08 AM
Ken's CAD Models
dz1sfb's Avatar
Originally Posted by Tommee
Ken I'm watching your work very closely (it is great ).
What do you think is slower and more stable flier, OK or BB? Because next build is OK, it looks fantastic.

That is a loaded question!

I am going to pitch for the Oshkosh Special, and before everyone gets in an uproar, let me tell you why and why not.

First the not; It is not because it is one of my planes. Truth be told the Oshkosh Special is really a modified Blue Baby. It stands on the shoulders of the Blue Baby and its designer Tony65x55, and is a tribute to Tony's design style.

Now the why; As previously stated the Oshkosh Special is a modified BB33 with a UC wing.
  • 50 sq. in. more wing area. This means your wing loading is decreased. Slow flight is a function of wing loading. The lighter its loaded the slower it can fly. The cost of the extra wing area is 6g in foam.
  • Tail moment increase. This improved the yaw/roll harmony by giving more dampening, and offset the extra weight in the nose from a larger motor. More tail moment also helped yaw stability that was reduced with the increased wing span.
  • AUW of these models was 10.5 oz. I believe that you could shed another ounce to ounce and a half by going to a lighter motor (such as a Blue Wonder, that is 15g right there), changing to 5g servos (8g savings here), Then a bit lighter wire on the landing gear. I was using 2mm, but you could opt for 1.5mm (43% reduction in mass over the 2mm), and a smaller battery (500mAh vs. 900 mAh).
You know, the bottom line here is I believe it would be worthwhile to try the OKS wing on a 33" BB. As long as it does not rock while flying once trimmed out. The rudder will be just fine.

An equally important consideration is build and material qualities. You can have a great design, but be built in a most crude fashion. The Blue Baby design is very forgiving of builders problems. However if you build it straight and light ( minimum glue and reinforcements ), you will be rewarded with a radical improvement in flying qualities. Material properties, such as foam density are huge factors in finished weight and strength.
I have found Depron to give the nicest appearance, but be the least survivable material. It fractures the easiest from the shock of impact, and is the heaviest of the foams I have experienced.
The Owens Corning pink FFF has improved in the recent past, and I use it now for builds not requiring or needing paint. It is the cheapest and lightest. However it takes alot paint to get good color, and it is pretty soft. Not a bad choice though.
The traditional blue FFF from Dow is still my favorite. It takes paint well and sands good also. It is marginally heavier than the pink, and a little tougher.

Last edited by dz1sfb; Dec 22, 2010 at 09:23 AM.
Dec 22, 2010, 09:46 AM
Registered User
Tommee's Avatar
You bought me. I need to build one OK ASAP.

Currently I use XPS as material, I wanted to try depron. I strive to build as light as possible so maybe I need to stay away from depron. I don't have access to that blue foam stuff...
Next OK and BB will be laser cutted with minimal glue and I expect them to be very light. Can't wait...
Dec 22, 2010, 10:45 AM
You will love the OK. Kens simple design changes have taken a great design and created a fantastic one.
I have 2 BB24's and one OK30. The OK 30 is my fav' RET plane.

Dec 23, 2010, 03:11 AM
Registered User
Tommee's Avatar
Here is the crash, nothing fancy, only dumb thumbs

Only damage to the plane was this crack, nice

Blue Baby Crash (0 min 39 sec)
Dec 23, 2010, 07:07 AM
Ken's CAD Models
dz1sfb's Avatar
You have a great sense of humor! Love the video

Are you using magnets on the front of the wing as well?

Latest blog entry: Ken's CAD Models new web site
Dec 23, 2010, 08:29 AM
Registered User
Blu Baby (10 min 51 sec)

I love this plane.
Dec 23, 2010, 12:42 PM
Nice Video.
Dec 24, 2010, 10:10 AM
Crash it first, Then fly it
Griffindor's Avatar
The magnets are a good idea for a crash
Dec 25, 2010, 03:18 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar

Merry (White) Christmas From Alabama...

To all fellow foamie-nuts, a rare Merry White Christmas from the South! No skis or snow removal equipment here, so my BB is grounded - I think we got about five inches at the house.

I want to thank all vets, past and present, combat, non-combat and Cold War for your service. You are one of the reasons we can celebrate the holidays. Your service is appreciated, God Bless you all!
Dec 26, 2010, 11:44 AM
RC Adddict
Wilfor's Avatar

Somewhere in Petrinja i hear they make really good salami
Dec 26, 2010, 01:46 PM
Halifax Electric Flyers Assoc
dghutt's Avatar
Here's my 10-year-old's Christmas present -- a 20" BB scaled down from the 24" plans. It's running a Turnigy 1400 2000kv motor, 6A plush ESC, 3.6g servos and a 2S, 240mah pack, built in 3mm depron with an EPP mono-block. It also has wing-tip LEDs for fun. We maidened it outdoors today.

The 6040 prop was too much for this power set-up but a 5030 worked pretty well. We'll also have to play with the CG, although a bigger lipo pack will help a lot both in weight and power.

It flew nicely but it's extremely twitchy at this scale. I wanted something that could handle indoor and out, but the slightest breeze made it pretty tough to handle outside. I think it will be great indoors. If I had a do-over I would not have scaled the 24" plans.

Dec 26, 2010, 05:51 PM
If it flies, I will crash it
mxspode's Avatar
The 24's are known for being a bit on the quick side. I had one for a short while. The original BB33 was designed to be an indoor plane and it works pretty well in those conditions. I have flown mine in a grade school gym with no problems at all.

Dec 26, 2010, 08:33 PM
springer's Avatar
yeah, it's tough to get the wing loading of a 24 (or smaller) down to what you can get with the larger versions (figures as using pretty much the same equipment). My 42 will lift off slowly within a few feet takeoff run, the 24 will lift off in a few feet, but at half throttle and jumps into the air as it's overpowered for it's size.

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