Mar 10, 2004, 03:23 PM
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JB's Avatar

DC-9-21 EDF model

Some fellow modellers have encouraged me to open this new thread and show details of my current project: A Douglas DC-9-21, scale 1:11. SAS phased out the aircraft last year, but I managed to have a close look at some of them and take several photos and measurements before they were ferried to the US – some of them with my friend Torben Back Sørensen at the controls.

I wanted a large model in order to accommodate several scale features and to have a docile model to fly. The scale 1:11 will allow for near scale nacelles with 120mm fans powered by HP 370/20/A3S motors = some 3kp thrust per engine.

Main data:
Span (overall) 2586 mm
Length (overall) 2893 mm
Height 762 mm
Wing root chord 493 mm
Tip chord 100 mm
Wing area 76,83 dm2
Est. all up weight 9 kg

Main features: Scale retracts with doors, Wheel brakes, scale flaps incl. inner triple slotted section, full leading edge slats, spoilers.

My first concern was transportation. It has to go into a normal passenger car. I decided to make the fuselage in two sections and detachable wings, tail and rear cone. They can then be stowed into a 60x70x130cm box....I hope!

More pictures to follow shortly......
Last edited by JB; Dec 23, 2010 at 04:20 PM. Reason: Spelling
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Mar 10, 2004, 03:50 PM
Registered User
Love The Idea of a DC-9. Presumably foam. Would love to get the plans and build one myself
Mar 10, 2004, 04:20 PM
Fly Brushless!
Hawker's Avatar
JB, sounds very nice! Can't wait to see more pics.
Mar 10, 2004, 05:47 PM
EDF rules... :)
AirX's Avatar
Cool likes like a few airliners coming out. JB we wopuld love ot see the design and build as you progress through it.

Eric B.
Mar 10, 2004, 06:48 PM
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RCParkflyer's Avatar
signing in to follow the thread, I'm most interested in the LE Slats set up and how your going to make this "transportable" Who makes 120mm Fans ?
Mar 11, 2004, 12:35 AM
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Rudi's Avatar
JB, if your DC9 will be so wonderfull as your Airbus A300 I vote you for the title "King of Modellairliners"

Greetings from vienna


P.S Go on and give us more photos please !
Mar 11, 2004, 05:10 AM
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JB's Avatar
These are the parts to be assembled before flying. The wings are fitted with four dural studs to be locked to the centre wing by 3mm grub screws. The studs are secured to the carbon tube main spars by cyano and kevlar.

The two basic fuselage frames consist of five longitudinal carbon tubes fitted with dural end pieces at the joining face. Five 2mm screws are used for assembling the two halves of the fuselage.

Two 4mm titanium rods protrude below the vertical tail and fits into the fuselage where they are secured by 3mm grub screws. A further 2mm screw is fitted at the foremost end of the tail.
The horizontal tail is attached at its pivoting point by two nylon brackets secured to the vertical tail by four nylon screws. A trim device – to be designed later – will be linked to the tail near the leading edge.

Having solved the assembly I could concentrate on designing the various components. I always start with the most complicated items. If they cannot be made there is no point in going any further!

I started during the winter 2002/2003 with the undercarriage. Then the triple slotted flap sections and the leading edge mechanism.
More later.......
Mar 11, 2004, 02:58 PM
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JB's Avatar
Nose Gear:
Flight and maintenance manuals show perspective drawings, but no actual dimensions so I had to take a few measurements on the gear to get the proportions reasonably right. The linkage activating the doors is done in a clever way and I wanted to do the same on the model.
Mar 11, 2004, 03:02 PM
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JB's Avatar
I worked several hours at the pc to make a set of drawings and then at my small lathe/milling machine to make all the bits and pieces.

The leg has a build in coil spring and direct steering is provided through a servo fitted on top of the leg allowing small turning radius on the ground. The rims are machined in two halves and joined by eight 1mm screws and nuts. A 4mm alu-nut and a similar locknut secure the wheel to the shaft.
Mar 11, 2004, 03:06 PM
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JB's Avatar
Here is a side wiev:-
Mar 11, 2004, 03:23 PM
Fly Brushless!
Hawker's Avatar
JB, your work is just amazing! Talk about being inspirational.
You are THE Master Modeler of the Ezone in my book!

Thanks for the great pics!
Last edited by Hawker; Mar 12, 2004 at 12:06 AM.
Mar 11, 2004, 04:05 PM
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Iso Octane's Avatar
Oh... wow!

Can't wait to see more!
Mar 11, 2004, 05:22 PM
Lori, hey, you're home early
CarreraGTSCS's Avatar
He-llo! Here I am sanding blue foam and there you are engineering miniature parts that could pass any A&P inspection. Simply amazing!! I'm not worthy.
Mar 12, 2004, 12:02 AM
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Rudi's Avatar
Incredible, what it is possible Against you JB I am a small sausage, please go on and share with us your construction !

Thank you

Mar 12, 2004, 12:08 AM
Official Boat Bum
Eddie P's Avatar
JB, this has to be the ultimate Airliner project so far. Amazing! I am extremely impressed.

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