LS1Chris

Hi, I'm an Airframe & Powerplant techican, this fall I want to start construction of a Boeing 777-300ER model aircraft using ducted fan glow engines.
It's currently in the designing stage, here's the basic info as of now:

Wingspan excepted to be 7 to 10 ft
length is between 8 1/2 to 11 1/2 ft keeping in ratio with the wingspan size.
wing is to have a foam core, then composite applied
flaps, alierons, air landing gear, lights is to be used
two ducted fan engines (howcome I don't see many ducted fan used on model airliners ?, prop on a 757 shown in this forum and a turbines on a C-17 project)

ducted fan engine size, don't know yet
weight, don't know yet

the center will be made mostly of composite and be of a half circle, for attaching and removing the wing for transport, access to control linkages and onboard electronics
a center fuel tank
nose gear steering linked to the rudder (a heavy duty servo is gonna be needed for this one using long linkages)

sounds good?

the biggest problem i am encountering is how wide (leading edge to trailing edge) and thick (top to bottom) or chord does the wing have to be for a effective design for use in a flying model?
i'd like to keep the same shape as the real 777-300ER wing shape (yes i mean the raked wingtip too) but thickness and width (leading edge to trailing edge) won't matter
Here's what the wing shape looks like on a real 777-300ER:

Mike James

if you haven't already done so, you might pose this question in the "Jets" forum, to see who else has done the 777. But...

I bet that if you keep it light, and use slotted Fowler flaps, as on the original, you should be able to use the scale wing size. A friend of mine builds and flies relatively heavy models, but uses slotted flaps on most of them. When we first go the the field, he gets a lot of heat about the weight from "armchair pilots", but ALL of his planes take off, fly, and land nicely, thanks to the slotted flaps.

It's easy enough to enlarge the wing later if you find it to be a problem, but if I were building it, I'd start with the scale shape. If it works well, then the fact that it's true scale is just one more bonus you can brag about at the end.

I love Boeing. Please keep us posted as you progress with this project. I'm sure we'd all like to see the process.
Happy flying.

LS1Chris

Mike James,
I was thinking of how to construct the fowler flaps in the 777-300ER wing, before setting everything out to draw on the drawing board to minimize future major modifitations, before i was thinking of 4 feet wingspan but i scrapped the 4 ft and started on a 7 to 10 ft wing span because i want the plane to look a bit big and have big engines.

I saw your website on the flap construction but cannot see what is the real setup is coming from in using to operate the flaps, can you tell me what's the construction setup in your setup and your friend's setup in heavy models?
I am interested in designing this to see how many servos and setups i will have to fit inside the wing. The first part I will be designing is the wing itself, then it will go to the rest of the aircraft.
I already have alierons, lighting (green and red currently, may add strobes to it if i can get a kit that will enable me to),
landing gear mount location,
the wing spars (it will have 2 aluminum sandwiched spars for the front and rear)
wing mounting to the aircraft
engine plyon mounts may be made with balsa wood sandwiched with the aluminum in the middle for ridigity and attachment to the wing along with the throttle linkage and fuel line going to it and a vent line from it (it will have a center fuel tank with external fueling port for convience and quick fueling.

flaps currently under review for mounting and servos controls

once i reviewed and decide on which construction to use for the flaps, i will start drawing the componets in the wing itself and start discussing on these info for the wing foam core to be custom made:
1. Root airfoil and chord length
2. Tip airfoil and chord length
3. Length of wing panel (per side)
4. Setback of tip airfoil (amount of sweep back at leading edge)
5. Washin or washout (both root and tip if applicable)
6. Dihedral specification
7. Sheeting allowance
8. Leading edge length
9. Trailing edge length or thickness
10. Type of foam

Mike James

Chris,

Not sure what your question is, since there are many detailed drawings on my flap-related pages. ( http://homepage.mac.com/mikejames/rc...ite/index.html )

If you're asking "How does the servo move the linkage?", there are several methods. You can mount a standard servo just in front of one or more of the hinge points, you could use some sort of bellcrank setup, or you can use a jackscrew servo. (See the first "Flaps" page for instructions on how to convert several standard servos to jackscrew operation. ) You could even use air cylinders, as used on retracts. All of these are personal choice, based on the size and weight of your model, and how much money you're willing to put into your model. If you're going for the scale Boeing look, jackscrew servos are probably the best bet, since you'll need a lot of movement in your linkages. (triple-slotted Fowler flaps )

Good luck with your 777.

LS1Chris

You think this would be a good one for the 777-300ER wing?


On an another note, while browsing around for fowler flap construction, i ran across this, this would look good to power my 777-300ER

High Bypass Turbo Fan
Fan Diameter 180mm
Flow rate accros fan 100 m/s
Thrust 'static' 13 Kg (27 lbs)
Bypass Ratio 8:1
Core Mass Flow 0.18 Kg/s
Fan Mass Flow 1.6 Kg/s

Bax

My Feedback: (11)

You might also want to check this thread:

http://www.rcuniverse.com/forum/Scal..._518012/tm.htm

bax

wdawson1001

4

clscale-RCU

My Feedback: (7)

you might consider building a prototype from white or blue foam. Put a pair of glow engines with props for the test plane. this model would only be used for test purposes and flown until the shape and concept is proven. If you keep the basic shape and wing shape, no retracts but install flaps. modifying and redesigning this concept model will be easy and relativetly painless. then build the nice model from that...

good luck

jkwan12345

Where did you get those? They look just like the real things!

kdc

Chris, you did not mention your aeromodelling experience but I assume you are a very experienced flier if you are building the ultimate and most difficult type of model.

bofrcr

yeah!! I'd like to know where you got them too!!!

Mike Emilio

LS1Chris , , ,

Could you kindly fill in any more detail about those High Bypass Turbo Fans.

As you know, everything so far in todays market is basically fuel guzzling Turbo Jet.
I expect Turbo Fans would be totally revolutionary in today's market.

What site did those pictures come from????????????

kdc

The 777 has very tapered wings and will be a very tricky model to fly, especially if the wing loading is high. What is the wing area at the various spans you propose? What is the maximum weight ( at these spans ) to get a reasonable wing loading? Can a model be built to these low weights?

These are all the fundamental questions to think about first.