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Old Aug 31, 2010, 10:19 PM
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1/20 Glass/Depron MD-80, future kit prototype build

I decided to make a large depron and fiberglass MD-80, or super 80 quite a while ago. I have finally got it in motion. The main inspiration was Mike Neff (Neffwaffe on youtube) and his great depron airliners.

The aim of this is to make a "short" kit available to build this thing that will include all the plans/templates, and fiberglass parts like the nose, wing fairings, engine nacelle parts and maybe part of the tail. Also top priority is to make this thing ultra lightweight for slow and realistic performance of course. I think the dimensions I have chosen should allow this to be achieved.

I just finished the preliminary plans the will allow me to start putting this thing together. I have a shipment of depron and various carbon showing up any day, so when it does will get started on the wing and other progress as my business allows.

If you want to skim through picture gallery: http://rpmtech.smugmug.com/Other/Md-83/13605904_2JNmJ


Spects:
Scale: ~1/20
OA Length: 92"
Span: 72"
Fans: 70mm class
Slotted flaps, spoilers and retracts

Ok so here is a view of the plans for the wing and some preliminary plans for making the fuselage. Not very exciting now but i have to start this thread somewhere.



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Old Aug 31, 2010, 10:31 PM
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I had some interesting ideas on doing the fuselage. I was thinking to have a large 24" wide x 100" long full color sticker made. You would stick the sections to the depron, cut and bend to fabricate the fuselage.

However the cost of the sticker in the $100's, and the fact that the nose and other parts would have to be painted anyway kinda killed this idea...So for this first one it will be just painted.

Another thought was to cover the wings with silver vinyl sticker sheet, but will have to see, because it would be heavier than paint im sure.
For the windows im thinking to have a roll of stickers made, if nobody wants to cut out all those windows like me.

Anyway i'll update this as it progresses.
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Old Sep 01, 2010, 03:09 AM
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Old Sep 01, 2010, 11:51 PM
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Wing construction

Ok we start with the wing. Main structure from 6mm and 3mm depron and .6mm x 3mm carbon spars. You take the full sized plans, cut out the templates, and lightly glue to the depron of proper thickness for the part with spray adhesive. After your done cutting paper is peeled off. Simple stuff.

I will make complete instructions, but for obvious reasons im not going to post ever little aspect of the build here.

My wing plans worked great, only one minor revision needed

3mm Clark Y ribs, 11 per panel.


6mm main spars


6mm trailing edge spars


6mm bottom inboard wing


And the 6mm inboard bottom attached to the 3mm outboard bottom skin


Ribs,spars and top carbon in place


Bottom, showing retract mount area sized for the Lander style electric gear, and the bottom carbon spars inserted into wing in a slit below spars. this wing is way too rigid! I actually wanted it to flex like real airliners, So I really think the carbon/depron/carbon is a little overkill. But hey its the first one


the two framed wing panels. Time to make to this point including cutting out all the parts: 5 hours


Next will be to make the flaps,ailerons and spoilers and their mechanisims before installing top skin. So far very easy and fun work
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Old Sep 02, 2010, 12:38 AM
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Looking good. Maybe a Flat Carbon piece would give the "bend" your looking for.

An MD-82 to keep your drive going:
DC-9 MD-80 MD-82 (5 min 1 sec)



Wing flex on Takeoff! Nice!
RC_boeing747 (5 min 29 sec)
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Old Sep 02, 2010, 01:10 AM
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Both great videos! But that nice 747 need fan upgrades big time, they sound terrible. Yep thats some flex, cool.

The DC vid was very nicely done!
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Old Sep 02, 2010, 08:48 AM
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Great Build.
Your MD is almost the same scale as mine.
May I ask you what you have in mind when you say ultra-low weight?
And what amount of thrust you think you will need?
And are you going to have the wings fixed to the fuselage or removable?

Thanks & Cheers
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Old Sep 02, 2010, 12:10 PM
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Well as light as i can make it, but not be too flimsy. I already realized that i could have used 3mm and 2mm for the bottom of the wings instead of 6 and 3
So as i go i will see where weight can be saved for the final design. I dont have a target weight because its pointless, just design and build as light as possible and see where it comes out.

Power will be middle of the road 70mm fans. I think I'll use the Sickle fans, cause they look and sound good. Hot 64's could be used too. Use the 64 on the dc-9-20 version with smaller engines

Yes wing will be removable, via the old dowel and nylon screw routine. It's a little big for one piece that could be a pita.
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Old Sep 02, 2010, 01:58 PM
Some epoxy & it flies again...
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Old Sep 02, 2010, 09:00 PM
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Flaps

Flaps are made from 2mm depron, with 6mm leading edges and carbon strip hinges







The leading edge of the wing gets sheeted with 1/16 balsa. Depron as great as it is, is crappy for this job. Yep the carbon is totally unnecessary for spars now. Oh well the prototype will live with them
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Old Sep 02, 2010, 09:29 PM
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Nice shot im using for wing build details

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Old Sep 03, 2010, 01:11 AM
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Looks Great!
Thanks for the Info. I'm very exited about this build and curious how heavy the model will turn out.
Neffwaffes original big MD80 had no retracts, flaps and detachable wings but I guess that the flaps will make up for the increased weight of your bird and result in a similar stunning landing performance.
Watching other people build depron airliners is a lot more relaxed then doing it yourself

Cheers
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Old Sep 03, 2010, 09:24 PM
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Finishing up the flaps and mechanisims before I skin the rest of the wing top. Flaps are actuated by one servo, as are both spoilers. There is a small pin at the TE that connects the inboard and outboard flap sections so they both actuate together.

Aileron, the leading edge is covered with aluminum tape, the rest with clear packing tape (no fibers just clear)and painted. The adhesion for the packing tape was helped with a light mist of spray adhesive.


Same for the flaps. Very little weight added with this finish and it looks acceptable. The whole bottom of the wing gets painted silver, no tape.


Pin that connects the flap sections. Works really well, no slop at all and easy to do.


Those with a good scale eye will note that I made the aileron chord a little wider than would be scale. I tend to do this to everything, bigger surfaces dont hurt on a model.


Servo linkage can be seen on the inboard flap.


Spoilers linkage, spoilers deployed


Spoilers retracted
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Old Sep 03, 2010, 09:32 PM
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Quote:
Originally Posted by chochmah View Post
Looks Great!
Thanks for the Info. I'm very exited about this build and curious how heavy the model will turn out.
Neffwaffes original big MD80 had no retracts, flaps and detachable wings but I guess that the flaps will make up for the increased weight of your bird and result in a similar stunning landing performance.
Watching other people build depron airliners is a lot more relaxed then doing it yourself

Cheers
Thanks.

Depron is a dream to work with, this is really the first plane I have made out of it. No wonder its so popular. It beats balsa just about everywhere but for sheeting leading edges because the grain of the wood really is perfect for this. Wood sands nicer though, and is not attacked by petro chemicals. The combo of the two is great.

Well im trying my best to keep the weight low, but flaps and spoilers are gotta have on an airliner.

You know the biggest pain and time consuming thing is to figure it all out, where linkages go, what geometry, where this goes, what that is made from etc. Thats my aim is to make this plan so people can concentrate on building rather than figuring stuff out. Plus the fiberglass parts will help to have a much better looking model.
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Old Sep 03, 2010, 10:49 PM
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Tight work! I cant wait to start this build!
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