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Sep 05, 2008, 09:40 PM
Slow Flyer
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The Bionic Bee - My Cox Lazy Bee story and rebuild

The Cox Lazy Bee - Our first airplane and entry into the RC arena

Many years ago, my brother and I purchased a Cox Lazy Bee (LB for short) from a Tower Hobbies Catalog. This is a little story about the events leading up to that purchase, our experience with the LB, and then my current attempt at rebuilding the LB.

The Early Years
The way I remember it is that we had always been impressed with a $350 helicopter that we used to see in a popular catalog. I believe the catalog was BEST or Service Merchandise. Luckily, we never got it. I am sure we would have either cut our heads off or created severe damage in the neighborhood. We did, however, have many rubberband powered gliders, various rc cars, and even a Cox line-controlled gas plane.

Jump ahead many, many years to a family gathering down at Galveston where my family rented a beach house for a week. I thought it would give us something cool to do, so I ordered it and had it Fedex'd to meet us at the beach house. We read the instructions and put it together. The instructions warned against flying in wind over 5mph, but we thought we knew better. We didn't.

"Flight" Attempts
Our first flight consisted of finding a parking lot and trying to do a ROG takeoff. I don't remember the particulars, but it didn't go too well. I am sure my brother blamed it on me. We tried a couple more times with a hand-launch, but we still couldn't get it in the air...for very long. A couple of pieces of broken styrofoam later, and a little discouragement, and we were back at the beach house.

In later weeks, we tried over and over to hand launch it and keep it in the air. We threw it high, we threw it fast, we threw it far. We threw it into the wind, and we threw it against the wind. Heck, if it doesn't work correctly following the instructions (into the wind), try the opposite. Right? Wrong!. We re-read the instructions, but it still wouldn't fly for longer than 60 seconds.

We finally stopped trying and the LB was packed away. Eventually, it ended up in my garage on the top shelf behind the fishing equipment. Each time I went fishing or rearranged the shelf, I would look at it and then move on. One day, one day.

Years Later
Years later, my brother returned to RC with a 2-channel helicopter. That didn't last long, so he upgraded to an Esky HoneyBee. That went better, but there is a steep learning curve for helis...he found out. I picked up an Esky Lama V4 to show him how it was done. I didn't. I was too afraid to fly it in the house and it didn't fair too well out in the elements. I shelved it.

My brother moved to RC cars and I moved to RC planes. We both had good success this time. A couple cars and a couple planes later (you know the routine), and we were still "in business". Next, my brother joined me in the plane arena with a Parkzone Micro Citabria...and then the micro Cessna. I had a Skyfly, Slo-V, and a micro cessna.

The Lazy Bee Revisited
With all this "success" and confidence, the Cox Lazy Bee came into the picture again. "I bet I could get this to fly now", I thought. I took it down from it's back shelf and started cleaning it up. One of the first things I did was check the transmitter, receiver, and servos. Surprisingly, they all functioned. At first, I thought I would get her working in the original condition as built and prove that I could fly her.

2-channel, fuel, and CG
One problem, I noticed that this was a 2-channel plane. The left stick controlled the rudder, and the right stick controlled the elevator. What!?!, no throttle control? Right on. This was a little fuel engine that you cranked up, got to running speed, and then let her rip. The problem was that she didn't "rip". Maybe we never got the engine running properly...or maybe it was something else? It had a very small prop, so I doubt the torque or pull was what it should be for a plane with this shape and weight (2 lb'r). The other thing I now know that I didn't know then, was that the instruction booklet didn't say a word about CG. What is "CG", you ask? CG stands for the center of gravity. Basically, it is the point at which the plane balances properly. Thinking back, the plane either sunk like a bloated, featherless bird, or "porpoised" up and down...until it hit the ground. Either way, those are symptoms of a mis-set CG. I also remember that the "fuel tank" (laughing) leaked pretty badly...and messily (new word there).

New Idea
Okay, so I realized that the plane had some real shortcomings. I decided that it wasn't worth resurrecting a plane that had so many problems (at least in my mind). I decided I would rebuild her in the style of the day. That meant integrating many of the improvements in technology and efficiency that have been developed in the RC field over the past 10-20 years. The challenge is giving her the right components and making the right changes. This should be fun.

NEXT: The Lazy Bee turns Bionic!
(more to come, including pictures)

Bionic Makeover
I started with the main wing. It was yellowed from fuel, grime, and age. Both wingtips were broken and glued. The decals were discolored and peeling up. The wing was beat up.

I removed the decals and cleaned and repaired the wing. I painted the wing with white Krylon H2O latex spray paint. I used the old decal design to stencil and spray a new one. I used black and yellow striping tape to finish recreating the design.

Next came the logo. I found a bee that I liked on the net. I cleaned it up, resized it, altered it a little in paint shop and printed it out on heavy photo paper. The lettering style is called "Magneto". I cut out the designs and used spray adhesive to mount them to the surface.

For the bottom of the wing, I used the same batwing or modified flame design...only this time in black. I used the same black and yellow striping. The dihedral or upturn on the wingtips called for a design of their own. This area will be highly visible on flybys. I decided on flames. To make the flames, I found a design on the net. I put them into powerpoint and resized them. I them cut them out and used them as stencils. I used red spray paint to fill in the design and followed up with highlights of yellow striping tape. I repeated a similiar design and technique on the bottom of the tail wing to match.

Wing Attachment Mod
With the new design, the rubber bands that originally held the wing on would partially cover the homemade decals. I thought about doing nylon wing bolts, but that would require buying some more parts. Also, in the case of a bad wreck, the wing could possibly rip right through the fuselage. Instead, I drilled holes and glued bamboo skewers into the leading and trailing edges of the wing. I used the existing rear dowel to attach a rubber band and loop it over the top of the new bamboo dowels. For the front, I repeated the setup by drilling a hole in the fuselage and adding a corresponding dowel. The new system will allow the wing to be held on securely, but will flex if the wing takes a hard hit. This will minimize damage, allow the wing to be easily and quickly removed, and will allow full view of the decals and wing striping.

For the fuselage, I kept the original decals, but painted a black racing stripe where the blue windows used to be. I carried the black stripe across the front of the plastic cowling. I put a fresh coat of red on the cowling. To finish her off, I put mini bees on each side of the rudder.

NEXT: Landing gear, tail wheel, and motor.
(Keep checking back.)

It has been a while...a long while. I have to admit that I got discouraged and shelved the Bee for a while. But I digress. Let me pick up where I left off.

Landing Gear
The Bee came with a straight axle that ran through the cowl and was flanked by two hollow plastic wheels. I wanted to replace the tiny propeller with a much larger one, so I bent new landing gear out of hanger wire. I designed gear that held the front of the plane up several inches from it's original position. It also reached forward to help the plane resist the temptation to nose over upon landing. Unfortunately, I couldn't keep the gear locked in place. I scrapped the first design, built the new gear out of heavier music wire, and included a flange on the gear that could be bolted to the inside of the cowl. This time it worked. I finished off the wire struts with gear pants that I cut out of foam and painted red.

For the wheels, I chose solid foam wheels that were about the same size. I painted the hubs red. The wheels are held on by your standard wheel collars and held in place laterally by a prop spacer and spring.

Tail wheel assembly
The original tail gear consisted of a small plastic wheel and wire. I wanted to add steering to the new Bee, so I put in a steerable tail wheel. It is made out of alumimum and the wheel is hard rubber. It works by way of an arm that is glued inside the rudder. When the rudder turns, the wheel turns the plane. I am happy with the way it turned out, but I should have either gone with a lighter design, or at least waited to see if the plane could stand the added weight at the tail.

I ended up going with the BP 8YSS Outrunner Brushless Motor With Short Shaft from This range of motors is listed as class 400.

For 2-3 Li-Poly Cells (7.2-12.6V)
Recommended props: 9 x 4.7, 10 x 4.7, 11 x 4.7 Slow Flyer
31 mm diameter x 46.5 mm length
Maximum current: 12A
No Load Current: 0.6A
Weight: 61.2 grams / 2.16 oz (everything shown in picture)
Comes with plastic gearbox housing for stick mount
3mm shaft diameter
10mm x 10mm stick mount
Kv: 890
12 Stator Poles, 14 Magnets

Configuration: Propeller: Volts: Amps: Thrust:
Direct Drive 1047 11.1V 10.9A 21.5 oz / 602 grams

This motor would allow me to run a 1038 or 1047 prop. I am more interested in thrust than speed. Afterall, she is a slow flyer. I did a couple preflight static tests and this motor appears to have plenty of power for this plane.

Center of Gravity
After loading up the plane with the new electronics, I attempted to find the CG.

Here is some info on the plane:
Wingspan – 38” (96.5 cm)
Wing Chord – 14” (36 cm)
Wing Area Estimate – 419 sq inches
Plane Weight – 2:1.2 oz (941 grams) - This includes a TP prolite 3s 2200 lipo (5.1 oz/144.5 grams), esc, servos, motor, etc

Based on my review of Lazy Bee threads on this forum…and other CG threads, the CG should probably be somewhere between 25-30% of the wing chord. I measured some of my other planes and found they are closer to 30%.

So, based on my wing chord, it appears that the CG should be at the 3.5-4” (9-10 cm) mark, but the plane actually balances around 5” (13 cm)…or 36% of the wing chord.

I was not a happy camper. With the current motor, battery, electronics, etc, I had to add anywhere from 3-3.5 oz to the front area of the plane to get it to balance at 25-30%. I accomplished this by adding Sculpey clay inside the front of the cowl. While this seemed to get me in the area of the desired CG, it made the plane quite heavy (I thought at the time) like a brick. With the weight added to balance the plane at 25-30%, it weighs 2 lbs 4.4 oz (1003 grams). Based on my estimate of the wing area and AUW, my wing loading would be anywhere from 11 to 12 ounces per square foot. I later learned that this wing area to weight ratio would put it in the acceptable range for a beginner plane. Still, I didn't like the idea of all the dead weight (clay) in the nose. I got a little discouraged and put the plane back on the shelf.

In the meantime, I ordered a few more batteries for other planes. One of those was a 3s 2150mah Rhino lipo. It weighs 186grams. This was quite a bit heavier than the Thunderpower battery (144grams) that I had previously installed.

With renewed interest and ideas, I pulled the clay out of the cowl, weighed it, and then proceeded to gather and sort thru the electronic components to find a combination that weighed as much as the clay. Without too much trouble, I was able to match and then slightly exceed the needed weight to reach my desired (and theoretical) CG.

I ended up with the following list of components:
Motor: BP 8YSS Outrunner
Prop: APC 10x3.8 Slo Fly with large aluminum collet spinner
Battery: 3s 2150mah Rhino
Speed controller: Castle Creations T-Bird 36 (used it for the extra weight)
Servos: GWS Park LF (17grams)
Receiver: AR6100e

NEXT: Ready for the Maiden Flight
Let's hope that the CG is in the right position...and/or not too far off.

Maiden Flights
Success! I finally got a break in the windy/rainy weather...
Hand Launch - a little unstable on the toss, but she quickly leveled and gained altitude. I did about 8 circuits and then brought her down in the grass. She seemed like she was flying a little hot (nose heavy), but I don't have much to compare her to (apples to apples) yet. I think I needed just a slight touch of up elevator to keep her level. She is a little faster than I thought, but that could also be due to being slightly nose heavy.

Grass Landing - after the 8 circuits, I brought her down into some tall grass. Nice.

Rise off Ground 1 - I tried a ROG from the pavement, but with throttle, she turned to the left...I aborted takeoff.

ROG 2 - I tried again, while concentrating on keeping her straight, and had to hit elevator at the last second to leap into the air to avoid hitting some dirt mounds. This is another sign of being nose heavy. It was pretty scary...she went squirrely...and I was headed straight for a telephone pole, but pulled out of it at the last second...and into the air. I did a few more circuits and fly-bys and then headed back to the pavement.

Pavement Landing - Again, she seemed to come in a little fast. I brought her down a little rough to avoid overshooting the landing area (and into a building), but the landing was still a success...just wasn't too pretty.

I will experiment a little with the center of gravity to see if I can get her to fly a little more docile and slow. Other than that, she is done, and I am pleased.
Last edited by Bombay; Apr 13, 2009 at 09:24 AM.
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Sep 20, 2008, 01:16 AM
Registered User
Can't wait to see how it turns out. Wouldn't the 2409-12T motor have been a better choice?
Sep 20, 2008, 01:29 PM
Slow Flyer
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Thread OP
Originally Posted by st5150
Wouldn't the 2409-12T motor have been a better choice?
Perhaps, I am pretty new at this, but I was set on going with a lower kv and swinging a larger prop...and running off a thunderpower 2s 2100. I think the amp draw on the 2410-09 better matches my battery and anticipated prop size. We'll see.
Sep 21, 2008, 12:26 AM
Registered User
Yeah, your bee won't be underpowered with either motor. I have a similar story with another vintage COX foamie myself. Right now I'm leaning towards a 2409-12T but might spend a little more money on a motor with a stronger 4mm or 5mm shaft instead. I hear this is the weak point on these motors, with bearing failure being the next weak point. Then again, they're so cheap, who cares?
Nov 03, 2008, 01:45 AM
Suspended Account
Just wanted to jump in here and say that I am more impressed with your graphics arts talent than anything!

Those are some NICE flames you did!!!

I wish I had your talent...

Apr 12, 2009, 09:59 PM
Slow Flyer
Bombay's Avatar
Thread OP
I am relieved to report that the maiden flights were a success. One successful hand launch and grass landing, one aborted ROG, one successful ROG (albeit, scary), and one successful pavement landing (although not the prettiest). I think she is flying a little nose heavy. Better that than tail heavy. I will test the limits on future flights and try to get her flying as docile as possible.
Apr 12, 2009, 11:25 PM
The Flying Kiwi
velojet's Avatar
Originally Posted by Bombay
I am relieved to report that the maiden flights were a success.
Well done! I'm sure the Bee was glad to be back in the air, and eventually flying as it was meant to fly.

A chance of some in-flight pics in due course?
Oct 27, 2011, 11:10 PM
Suspended Account
Originally Posted by NoFlyZone
Just wanted to jump in here and say that I am more impressed with your graphics arts talent than anything!

Those are some NICE flames you did!!!

I wish I had your talent...


I recently bought the Lazy Bee Kit by COX and turned it over to an electric setup. 1400kv motor @180 Watts, walkera servos and airfield transmitter reciever pair.

Videos will follow...maidened her today, and will put bigger wheels for grass take off.

Oct 28, 2011, 01:41 AM
The Flying Kiwi
velojet's Avatar

Electrifying the Cox Lazy Bee

Originally Posted by tengarang
... I recently bought the Lazy Bee Kit by COX and turned it over to an electric setup ...
Well done, tengarang! I did the same myself about a year ago and have had loads of fun flying it since.

John V
Oct 28, 2011, 02:33 AM
Suspended Account
thanks john

gonna try her on 3s 2200mah setup with big wheels tomorrow. good to hear your keeping her active. i intend to keep this thread alive


Oct 28, 2011, 03:44 AM
The Flying Kiwi
velojet's Avatar

Electrifying the Cox Lazy Bee

Originally Posted by tengarang
gonna try her on 3s 2200mah setup with big wheels tomorrow
3S 2200 mAH is exactly what I've got mine on - suits her very nicely. I really do need to fit her with bigger wheels though for grass strip takeoff.
Originally Posted by tengarang
i intend to keep this thread alive
Oct 28, 2011, 05:28 PM
Suspended Account
Originally Posted by velojet
3S 2200 mAH is exactly what I've got mine on - suits her very nicely. I really do need to fit her with bigger wheels though for grass strip takeoff. Excellent!
Roger that...

So yeah the big wheels work well...with the "heavier wheels installed" i consequently had to give full elevator up trim ...

This was using the 850 3s 35 C battery.

Where did you place the 2200 mah in the vessle?
Oct 29, 2011, 02:03 AM
The Flying Kiwi
velojet's Avatar

Electrifying the Cox Lazy Bee

Originally Posted by tengarang
Where did you place the 2200 mah in the vessle?
Under the wing, on a tray I fitted, just slightly forward of CG. I'll try and take some photos this week.
Oct 29, 2011, 09:54 AM
Suspended Account
Originally Posted by velojet
Under the wing, on a tray I fitted, just slightly forward of CG. I'll try and take some photos this week.
Thanks velojet. I will be looking forward to those photos.
Nov 03, 2011, 05:49 PM
The Flying Kiwi
velojet's Avatar

Electrifying the Cox Lazy Bee

OK, here're the promised photos of my electrification of the Cox Lazy Bee.

I bought a rather battered kit on eBay (broken wing, indents in wing and fuselage, some missing decals, one missing control rod). After disposing of the Cox .049, I fitted a TowerPro 2410-08T 890kv with an APC 10 x 5E prop:

I removed the fuel tank and cut a hatch with the intention of fitting a 2S LiPo in there. However, this configuration proved to be rather underpowered, so I moved up to a 3S LiPo, but that moved the CG too far forward, so I left the TowerPro MAG8 18A ESC under the hatch ...

... and fitted a battery tray under the wing, above the two Hitec HS-311 servos, and behind the Robbe 35 MHz receiver:

That accommodates a 3S 2200 mAH nicely:

The only downside is that I have to take the wing off to change batteries:

Still, it's produced a really fun flying machine (admittedly, not as nice-looking as Bombay's) that's now been in the air for 50 sessions and will happily battle air currents that ground other craft:

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