Great Planes Dirty Birdy Build Thread - RC Groups
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Apr 23, 2012, 10:59 AM
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Great Planes Dirty Birdy Build Thread

Great Planes Dirty Birdy ARF Build Thread...coming soon!

Rusty Dose
Team Futaba*

*Futaba is imported by Hobbico Inc which owns Great Planes,Tower Hobbies and is the importer of O.S. Engines.
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Apr 24, 2012, 07:22 AM
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Build...assembly begins!!

The Great Planes Dirty Birdy ARF was created from the original Bridi design, acquired in an acquisition by Great Planes (Don Anderson) many moons ago.

The fiberglass fuselage used in this ARF was created FROM AN ORIGINAL DIRTY BIRDY EPOXY GLASS FUSELAGE!!!!!!!!! I have read posts that inferred that Great Planes, insert your preferred uneducated, bad guess, erroneous comment of your choice, did not base the model on the original airplane. The model's nose has been lengthened in order to accept a variety of engines (modern engines are longer!!). In my opinion, the model is exactly the same from the firewall back.

The second picture clearly shows the beautiful canopy fuselage concave transition...better than my carefully built wooden Dirty Birdy kit!

Ruty Dose
Team Futaba
Apr 24, 2012, 08:11 AM
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From my RCU post:

Thanks Rusty. Looks like the GP engine mounting pattern is "square". Can you investigate the possibility of an up-right mounted engine? Other than the engine mount holes lining up, I'm wondering if the cowl will fit with the engine mount set to accept large case engine like an SF?
Apr 24, 2012, 09:57 AM
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doxilia's Avatar

it looks like there might be right thrust built in from the position of the mount bolts. If so, is the FW also angled or is that to be shimmed with the mount?

It would be interesting to know the component weights of the airframe (fuse, stab & tubes, wing, cowl) to compare this to a built up version. Given your wooden version is almost at the same stage, perhaps you could weight that airframe too (despite the flying surfaces not being covered).

Apr 24, 2012, 10:32 AM
CPA# 39
EscapeFlyer's Avatar
That is .... WOW!

There really doesn't seem to be anything to worry about anymore.

Looking forward to the rest of the review!

Apr 24, 2012, 12:44 PM
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Fuel consumption and the tank size...

There seems to be some concern about the size of the included tank and fuel consumption. Pilots are commenting that they remember needing 16 ounces of fuel to feed the monster engines of yester-year.

My observations:

Props- The Zinger, Rev-up, Top Flite, MK glass, and even the trick DW props are infinitely less efficient and crappy relative to the APC props. Dave Guerin and I spent an afternoon flying a couple of airplanes with a half a dozen flights with the above props and endied with the APC. Fuel consumption was much different due to the throttle stick position.

Flight times- I am only able to concentrate for about 8 - 9 minutes so if I want about that much fuel. I have seen very good pilots fly the Hangar 9 Phoenix 7 for 12 - 13 minutes with the stock tank and the EVO and brain quit calling the manuevers, let a lone flying.

Header tank- There is room to add a 4 - 6 ounce tank in the space in front of the servo tray in the Dirty Birdy. A drawing is below. Note that the pump line simply connects to the motor.

I belienve that the included tank will provide 8 - 9 minutes of flight times. I will test once I fly it.

Rusty Dose
Team Futaba
Apr 24, 2012, 12:52 PM
Hope to get out of life alive
kenh3497's Avatar
One man's opinion here..... First a question 'cause I don't know. How long does it take to fly a pattern sequence?

IMO, if the sequence can be flown with the amount of fuel on board, then the tank is big enough. Now I do realize a lot of these will be flown as sport planes, which is another ball game!

Apr 24, 2012, 01:03 PM
CPA# 39
EscapeFlyer's Avatar
I would guess it could go longer... I saw someone post recently the Masters sequence took them almost 8 minutes... and that was taking his time and going long and wide on the returns.

Novice and Sportsman will go a lot faster.

8 minutes is a fair amount of time.... relatively speaking anyhow.

Apr 24, 2012, 01:39 PM
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For the Sportsman sequence, I think you can fly through it in about 4 1/2 to 5 minutes. For the intermediate, I think it takes me about 5 1/2 to 6 minutes per sequence. This could be a very nice entry plane.

Apr 25, 2012, 07:34 AM
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Assembly continued...more details

The retract bay is very innovative as it seals the compartment from the normal crap associated from glow fuel spray and supports the tank. (See photo)

How long does it take to fly the BPA Masters pattern?

7 1/2 minutes to landing if you have an organized and flowing turn around decisions. I typically use a 1/2 cuban 8 or a 1/2 reverse cuban 8 and a top hat with 1/4 rolls to move in or out due to wind conditions. I am going to add the header tank just because I want to fly the pattern 2x per practice flight.

Elevator and Rudder pushrod view. The photo shows the center tubes for the elevator pushrods, the large diameter on right is for the rudder pusrod and the skinny one is for a 72mhz antenna(?).

I will replace the pushrods with .06/.07 carbon fiber rod and Central Hobbies pushrod ends. Much lighter and super fast to create.

Glamour shot of my 1994 TOC Extra 300 sitting in the living room (my wife has not noticed it yet!)

Rusty Dose
Team Futaba
Apr 26, 2012, 01:51 PM
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Any progress???

Apr 27, 2012, 07:24 AM
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I have just about gathered all of the parts and considering building another DB without retracts and no tuned pipe. This is interesting from the perspective of how well the model flies for the least amount of cost. If it would be really terrific it is easier to make a case for promoting very aggressively as an all around high performance model attracting a larger group of modelers.

I have the weekend to build the model and could almost be ready to fly it Sunday afternoon...

The Robart retracts will not be available until late next week and I am too impatient to fly this thing.

I need to order another kit!

Rusty Dose
Team Futaba
Apr 27, 2012, 08:41 AM
AndyKunz's Avatar
Get a Phoenix 7! (Sorry, I couldn't resist )

Apr 27, 2012, 09:49 AM
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I'll be getting my DB either tonight or tomorrow.

Just for Andy - been flying the snot out of my P7!! It'll be interesting to fly them back to back and see what the differences are.

Apr 27, 2012, 09:54 AM
Registered User
What is better than one Dirty Birdy?

Getting another!

Ordered and assume it will be here when I get the retracts and I will work to get one ready to fly by Sunday afternoon with O.S. 61 FX, muffler and minimal hardware changes from original.

Andy- I actually have (2)!! I also have the little UMX Gee Bee, UMX Beast and UMX S-Bach which I enjoy very much.

Rusty Dose
Team Futaba

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