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-   -   Making Extra 300 80" totally composites (https://www.rcuniverse.com/forum/giant-scale-aircraft-3d-aerobatic-110/2468914-making-extra-300-80%22-totally-composites.html)

macro-RCU 12-26-2004 01:15 AM

Making Extra 300 80" totally composites
 
I was learning too much here at RCU, so one year a go I'd start my first composite proyect.

It's an Extra 300 wich I get plans at the web.

This plans are for 1/3 Extra, so trying to learn more first before invest all that amount of money
I reduced plans to 80" wing span....

I'd take AutoCad and reduced it.

Plot plans and start to scratch first prototype, to be sure it will fly OK.

The designer say at the web that plane fly better than many kit there are outside (but at 1/3 scale)

so I take it slowly and make all very simple just for test.....

I'd scratch built first plane, cover with "moneykote" and put an OS BGX on it....

First flys were better I expect, and the guy who help me is a very good flyer, so with that in my mind I'd start
this project...

Please excuse my english, but I'll try to explain the best I can

macro-RCU 12-26-2004 01:21 AM

RE: Making Extra 300 80" totally composites
 
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First I must make a plug, so start with some door ply (cheapest)

I'd cut internal formers without any hole on it, weight will not matter

I'd buy some blue foam at isolation store and some polyurethane resins to fill the plug and get some stiff

macro-RCU 12-26-2004 01:29 AM

RE: Making Extra 300 80" totally composites
 
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The polyurethane foam works great (Thank's Mike for your web site)

The fuse jig I must make was taken from here RCU, take some time but it's cheap and easy to make

It's similar to Gator RC fuse jig, and I'll search threat for post here to thank's the guy who share it.

Here are the thrust line and cowl shape... thrust line is at fuse too...

macro-RCU 12-26-2004 01:32 AM

RE: Making Extra 300 80" totally composites
 
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Blue foam is a great material, sands easy and take little time to shape.....

Spinner is 3.25", and it's line is visible here

macro-RCU 12-26-2004 01:36 AM

RE: Making Extra 300 80" totally composites
 
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Because this is my first project this kind, I must asume will be making many mistakes,
but that is the lovely art of learn.....

I'd not take many pic's about process, so will explain what I do

macro-RCU 12-26-2004 01:40 AM

RE: Making Extra 300 80" totally composites
 
When plug was totally shape, was cover with glass and epoxy
4 or 5 oz wave (don't remember) was used;
when cured wave holes was filled with car filler and sanded to smooth

It takes some days, so then was when I'd think about foam cores.....

macro-RCU 12-26-2004 01:48 AM

RE: Making Extra 300 80" totally composites
 
I must say the Extra is my girlfriend's plane, she fly very good and make me start with the prototype,

but when I'd start can't stop with the project.....

So search the way to make the wing, stab and rudder cores with no luck here at my country; then
I decided to make some for cut it....

I'd get some electronics with the guys at some web page and start the cutting machine... it take me about three
months to finish and tune but works great.....

I'll post some prototype and cnc pic's tomorrow..... time to rest.

Merry Christmas

mglavin 12-26-2004 10:32 AM

RE: Making Extra 300 80" totally composites
 
Marco

You are to be applauded for your tenacity and effort. This is a huge project and you seem to have it well in hand. Good luck and please continue to share the process with us.

Mike Luvara had some information in the Pylon Racing Forum on a composite hollow core molded wing build. I 'll see if I can find the link for you.

If nothing else email me, I can provide some insight on our methods.

macro-RCU 12-26-2004 03:38 PM

RE: Making Extra 300 80" totally composites
 
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Thank's mglavin,
all about the project is learn to me, so the hollow wing system is welcome....

This is CNC cutting machine, very easy to make with industrial trash and some step motors (trash too)

The program was cheap, about 40 Euro, so it was ready for cutting cores...

I'd buy white foam 12Kg/M3 (I don't know about what imperial density it is) and start to cut cores for wing, stab and rudder

macro-RCU 12-26-2004 03:41 PM

RE: Making Extra 300 80" totally composites
 
At previous pic's you can see the fuse jig and over the CNC's table you can see some prop's too, the first Dynatrust 22x10, the second Mejzlik 22x10 and third is a test I'd make with a prop mould 22x10

macro-RCU 12-28-2004 12:22 AM

RE: Making Extra 300 80" totally composites
 
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With CNC cutter, now it's time to make vacuum....

Get some parts at industrial trash like freezer compressor and an old car diafragm...

Some conectors and presure lines.... some time later.....

vacuum system

macro-RCU 12-28-2004 12:31 AM

RE: Making Extra 300 80" totally composites
 
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After vacuum system, I need a wing cutting hole system, and that was made with a great idea from Scott Smith (really thank's).

It's a good idea and works great, so I get some material and make de hole cutting jig...

macro-RCU 12-28-2004 12:45 AM

RE: Making Extra 300 80" totally composites
 
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Now I'd cut core for fin and rudder and was sheeted with 1/16" balsa ....

Glue was 24h epoxy like many guys here at RCU sugested....

When sheeted, cut fin and was addeded to plug, totally aligned....

After that, all was cover with glass cloth and epoxy resin....

Some car fill compound and sanded....

Two heavy coats of K-36 primer and sand to get out the imperfections....

One more primer coat and it was ready...

Canopy was made with polyurethane foam and sanded to shape, some light wall fill compound and two heavy glass cloth with epoxy resin... Two K-36 heavy coats, some sand and ready too....

The chin cowl was separated of the nose, the same cloth and resin, K-36 and ready...

Pic's was made yesterday, too much time after mould was made, so plug are a little damaged...

macro-RCU 12-28-2004 01:02 AM

RE: Making Extra 300 80" totally composites
 
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Now it's time to make partition board and make the female moulds....

Apply wax 6 times and buff every one very good.....

The gap between plug and partition board was sealed with plastecine....

Two more wax and buffing .....

24 hours later two PVA light coats and let it dry 24 hours...

Mould layers was:

- Two heavy epoxy resin coats; it was colored with polyester resin black pigment
- three 6oz glass cloth
- one marine grade glass cloth

All epoxy was black tinted (I'd like it)

macro-RCU 12-28-2004 01:07 AM

RE: Making Extra 300 80" totally composites
 
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Some more mould pic's...

Pic's was taken some time after first fuse was layed....

macro-RCU 12-28-2004 06:07 PM

RE: Making Extra 300 80" totally composites
 
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I'd have not hot box, so somebody tell me It was not necesary "just let the piece to sun light".... I did it.....

BIG MISTAKE!!!!!!!!!!

a little part of mould get too much heat and deform about 1/16" in a 2" sq in at the tail part (just one halve)....

I don't like it, but learn is hard and take it with philosophy..... ok, next time first ask to RCU friends.....

OK, plug was taken off, the halves get wax and buffing 6 times....

Two PVA lilght coats, 24 hours to dry and it was ready to layup....

Layup was made next way:

- One K-36 light coat; let it totally dry
- One more K-36 light coat and before it dry start layup (Ola Fremming suggestion, thx for the tip)
- Some carbon tow for reinforcement at corners
- One light epoxy resin coat to get bubbles off
- One 5oz glass cloth
- One 5oz carbon fibber cloth
- Many time getting extra resin out with paper towels....

8 hours later I'd join halves and fuse parts with carbon ribbon...

Now I'd learn, and I'd make a hot box with cartoon box and electric heater...

After 24 hors, first fuse was done.... well.... all the work look well... but there are a little imperfection at the tail.... I'll work on it...

After trimming and sanding edges, fuse weight was 1,024 gramms (about 36.12 oz)

Fuse #2 will only have 1 layer carbon cloth, because fuse was very stiff and I can get it lighter.....

Stab and wing cores was made, but I decided to enlarge wingspan to 81.5" because I only have a G-62 at hand, and it is a heavy engine to get at least 30oz/ft wingload.... I'd expect a totally weight about 17-18 lb so with a light engine, it will be at 15-16 lb range

I prefer paint over plastic film, but since it will be my first paint attemp, all work is a test for me......

Wing and stab was sheeted with 1/16" balsa, holes was cut and was time to tube sockets....

Stab sockets was made 5oz glass cloth... wing socket was made 5oz carbon cloth.... aluminum tube was dural type... 1" OD for wing (may be 1 1/2" or 2" will be better but I'll try) and 5/8" OD for stab...

Wing and stab root was made with 3/32" balsa and one carbon layer... looks beautiful and it's durable....

Sockets was glued, wing and stab was aligned with fuse, ailerons and elevators was cutted and all surfaces was covered with 0.75oz cloth and polyester resin (old system). Cloth holes was filled with resin and microballoons....sand and sand.....when all was OK a heavy K-36 primer coat and more sand.....

macro-RCU 12-28-2004 06:18 PM

RE: Making Extra 300 80" totally composites
 
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Canopy mold was made same way than fuse's mold...

Canopy piece was made one layer 5oz carbon cloth...

It's very stiff, 1/8" balsa was used at both ends formers, and at botton two balsa ribbons to stiff...

Total weight after paint, clear coat and buffing: 100 Gr (about 3.5 oz)

macro-RCU 12-28-2004 06:26 PM

RE: Making Extra 300 80" totally composites
 
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Some more canopy's pics....

I'll be layingup fuse #2 tonight, so I'll show you more pic's about.

macro-RCU 12-28-2004 06:34 PM

RE: Making Extra 300 80" totally composites
 
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Now I need an undercariage, so I'd take the idea watched here at RCU and some web pages....

Desing it with clearance enough for 22" prop, so make a wood base, glued some formica, make balsa lateral walls and
it was ready for layup....

Carbon tow was used for it....

macro-RCU 12-28-2004 06:38 PM

RE: Making Extra 300 80" totally composites
 
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Main gear was reinforced with some carbon wave at axles area and fuse area...

Totally weight was 157 Gr (about 5.5 oz)

It was divides at two pieces for fuse fix....

macro-RCU 12-28-2004 06:46 PM

RE: Making Extra 300 80" totally composites
 
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Tail gear was made same way, but carbon clth was used.... very stiff and for my surprise when attached to fuse,

it make the same movements than a spring or car trust...

3de 12-28-2004 06:59 PM

RE: Making Extra 300 80" totally composites
 
Great work Marco!
Keep the pics comming!

macro-RCU 12-28-2004 07:05 PM

RE: Making Extra 300 80" totally composites
 
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Now was time for spinner....

I'd try to get a good mold from aluminum spinner, but prop holes don't let me do it good enough....

I decided to make a solid metal spinner shape and then make the mold....

Spinner is 3 1/4" diameter.... After mold was made, start layup next way:

- 6 wax and buffing
- 2 light PVA after 24 hours
- One light epoxy resin coat (for mirror finish)
- After 8 hours, one 0.75 oz glass cloth and paper towels for get most resin off
- After 12 hours, one layer 5oz carbon cloth, cut it 2 pieces overlaping each
- One carbon ribbon to reinforce aluminum base
- some chopped carbon tow with resin for central hole reinforcement

I'd take idea from a staudacher page.... I'll search it and post... Thank's that guys for share

Base plate was machined from dural aluminum to shape.....

macro-RCU 12-28-2004 07:18 PM

RE: Making Extra 300 80" totally composites
 
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Thank's 3de,

It's a very long travel but delicious...... make all this is enjoyable.....

Learning curve at this point is very complex and long, but since I don't mind to make bussines with it (It's my hobby only) I like to share all my learning process and mistakes too....

Hope all you enjoy it like me....

Some more spinner pic's

Weight was:

-cone 20 Gr (0.70 oz)
- back plate 47 Gr (1.65 oz)

macro-RCU 12-28-2004 07:31 PM

RE: Making Extra 300 80" totally composites
 
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At this point I'm yet testing make carbon prop's, I know about the danger side if a prop explode at lead and many carbon parts fly all around, so I can't say it is totally finished system, but I'm trying and learning....

Take many ideas from many web sites (one I remember is David Fee web site.. really thank's for share) and many other good people who share their knowledge.....

I'd take all about prop's very carefully......

First I made the mold with fast cast resin.... it is very dificult to make a good mold since there are some areas (hub area) that are not rigid enough to close and open mold many times...

Shape and balance must be closed to perfect....

There are many variables I must to take in count....

Here is where I am now:

Prop is Mejzlik 22x10... there are a Dynatrust 22x10 too but only for engine test.... the third with epoxy flanges is the first prop I'd made....

It was rigid enough but with some estructural problems between hub and tip..... I'm now changing layup to make it better and get good performance....


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