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Old Mar 30, 2002, 08:40 PM
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Acro-Bipe (Firefly-powered)


Hi,

When the wind blows...I build. Here is my converted $10 Acro-Bipe powered by the improved 4:1 Astro Flight (AF) Firefly coreless Cobalt motor. The tiny motor fits right into the stock nose of the Acro-Bipe! I used a small piece of masking tape around 1/2 the diameter of the motor to create a snug fit. Now that's an easy motor mount!

My Bipe weighs in at 3.7oz using an 8-cell, 120mAh, NiMH pack. This provides amazing power to the Gunther 5x4 prop at 850mA. The AF ESC for the Firefly has very nice linear control.

I used a GWS R4-P receiver and two GWS Pico servos for elevator and aileron control. My aileron control horns are typical biplane-style that extend to both sides for a future connection option up to the top wing.

Click here for a larger image.
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Last edited by Greg Covey; Mar 30, 2002 at 09:06 PM.
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Old Mar 30, 2002, 08:49 PM
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The finished bottom reveals tiny carbon rods to help support the fragile ailerons. These were purchased from Air Dynamics.

I used the switch/charger board from one of my old COX Viper projects. I've found that enclosing the battery for a self-contained unit works well on these tiny foam models. I just plug in the charge jack to peak the cells.

Click here for a larger image.
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Old Mar 30, 2002, 08:56 PM
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The elevator servo fits right in the slot used to anchor the stock rubber band.

Thin white hinge tape was used to help support the elevator that was never removed from the stabilizer. A tiny rod was bent to join the two elevator halves together. The whole stabilizer/elevator assembly was then slid from the rear after making a razor slice in the rudder. The assembly and rudder were then glued with white Elmers glue.

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Old Mar 30, 2002, 09:02 PM
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A close-up of the aileron linkage reveals the special servo arm created from 3 seperate arms.

The paint was removed entirely from the bottom wing using Scotch tape. Just press on and peal off, it's that simple! The ailerons were much easier to tape on the top side after the yellow paint was removed.

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Old Mar 30, 2002, 09:57 PM
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Blew out my flip flop
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Greg,

Why the long servo arm? Seems to me you are losing a lot of torque and centering ability. One click of trim on your tx is gonna make a huge difference at the end of that arm...you may have problems trimming the ailerons in flight. JMO, but I would just angle the pushrods out to the ail horns like this / \. I had one of these bipes and sold it...I paid 19.99 for it locally, and now I know about the site that sells them for 8.99, I may just have to get a couple!!

Good luck,
David Hogue
Old Mar 30, 2002, 10:37 PM
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That's cool Greg.

I've always wondered what people use that firefly for. I can't recall ever seeing an application for it.

I sure would like to see some video of that little bipe.

Regards,

Jeff
Old Mar 31, 2002, 09:51 AM
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Nice job.

Larry
Old Mar 31, 2002, 03:27 PM
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Thanks guys. I'll let you know how it flies soon.

David,

You have a good point. I get so used to my Futaba Super-8 computer radio that I forgot to mention that this setup requires that the gain be turned way down. The assumption here is that you have a computer radio.

It seems reasonable gain now but I can always use other holes closer to the servo for additional reduction.

Larry,

Hopefully, you'll be coming to the Xerox Gym on April 13th and you can watch me slam it into a wall.

Here is a picture of some of the components that I used.

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Old Mar 31, 2002, 05:05 PM
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I'll probably be hitting the walls before you do

btw, what is the wing loading of the bipe?
Old Mar 31, 2002, 05:51 PM
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Acro-bipe


Fire-Flys work great!
3.2oz with 8 50 Nicd two Wes-tech servos, GWS reciever. elevator rudder and throttle, And they paint good too. Model Masters Acryl brushed on.
Old Mar 31, 2002, 08:21 PM
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Eric,

Awesome looking Acro-Bipe!!! My God, you even painted the girl! I love the improved landing gear too.

I have a few questions for you...

I was going to use the 50mAh NiCds but I only had a 6-pack lying around with some loose cells that I could have added to it. I then spotted an 8-cell 120mAh NiMH pack that was similar size and weight to the 50mAh NiCd cells. Have you compared the two cell types for performance?

Is your AF Firefly the improved metal gearbox and boosted ESC current limit?

I notice that you are using a GWS prop. Have you tried the Gunther prop?

Regards.
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Last edited by Greg Covey; Mar 31, 2002 at 08:25 PM.
Old Apr 01, 2002, 12:01 AM
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Greg, neat little bird. Think it will fly OK on ailerons with that much dihedral. Have you been out to the pond with your Aventura II yet. I flew mine again 2 days ago. Man I like the way that thing flys off water.
Gofli, where can I get one of these little bipes for $10. Tom Smith, CD, Rhinebeck Jamboree
Old Apr 01, 2002, 12:31 AM
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Tom,


Here tis:

http://www.storeofwonder.com/store.html


Later,

David
Old Apr 01, 2002, 02:57 AM
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Acro-Bipe


Greg.
Yes I have used the 120 Nimh cells and they work great! I had a problem with my pack and they went thermal runaway and melted the inside of the plane, luckly its only ugly on the inside. The gear box is the old one and the speed control is from MTM and has no current limit. The GWS prop is the third one I've tried and is the best so far the old prop would only keep the plane up at full throtle now I can cruse at half throtle and stay up much longer. When I put in a new pack of 120 Nimh I'll get 8 or more minutes duration. I have not tried the gunther prop yet, it's not as pretty.... Eric.
Old Apr 01, 2002, 03:35 PM
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Tom,

It's too cold for me to pond fly yet.

A local float-fly is on May 18th so I hope to get my Aventura II wet then.

Eric,

Where did you end up with your CG on the Bipe?
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