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Wolfgang Matts Arrow


Sam Wragg
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Wing and tail cores were cut by Steve Dunning and are of exceptional quality (accuracy)

Please excuse the images for some reason they have up-loaded in the wrong orientation but i hope you can see my method of manufacture

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Tail cores

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4 sets of 1/16 balsa skins with alternated butt joints of sheet balsa to keep stress levels to a minimum

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Bottom skin & shut in position sat on a flat piece of 30mm Mdf board and given the lightest coat of Gorilla Glue

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Core in position

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Positioning of top skin

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Top Shut in place

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30mm Mdf placed on top of the whole assembly

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The whole weighted assembly left to cure overnight

Edited By Sam Wragg on 21/10/2014 13:18:40

Edited By Sam Wragg on 21/10/2014 13:19:26

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Leading & trailing edge glued on....... once again sometimes when i up-load an image something throws a wobbler Grrrr

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Joining of the two halves (Australia version)

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Tips added & semi finished prior to cutting out control surfaces but before i get carried away i always insert 1/32" ply web at the tips to prevent hanger rash.

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1/32" ply let into tip

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Ply just requires sanding to profile before I can move on to marking out and cutting out the control surfaces and line with 1/4" balsa

Edited By Sam Wragg on 23/10/2014 14:40:54

Edited By Sam Wragg on 23/10/2014 14:42:37

Edited By Sam Wragg on 23/10/2014 14:43:48

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After sanding everything flush the next stage is to cut out the control surfaces and line with 1/4" Balsa

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Marking out of area where the balsa skin is removed (top & bottom)

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Area of balsa skin removed then the core is gently cut away and sanded flush to the balsa skin

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Ready for lining

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Faced with 1/4 balsa using Gorilla glue, the tip ends will be faced with 1/16 balsa at a later stage

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The finished Tail plane, all that is required next is a 1/16 ply Web 4"long sinking in centrally at the joint of each half to aid strength

Sam

 

 

Edited By Sam Wragg on 25/10/2014 09:21:13

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Now that the tail is complete the next stage is to carefully mark out the fuzz using a template that was taken prior to joining

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Marked out area. if you look closely just above the CL you can see two reference points that was marked on both sides on assembly to aid alignment

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Cut away area. The next stage was to remove the bottom of the fuzz that was just tacked on

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Removed area that allows me to work inside the fuzz i.e.. installing all the control push rods and exhaust duct

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Construction of exhaust duct using 1/8 balsa

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Cut out section in pipe tunnel

Sam

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Hi Martyn,

I will be utilizing the same method as used in Magic, this was the main reason the underside of the fuzz was just tacked on with the provision at this stage of the build it allows me to gain access to lay in the control runs. I find it easier to do this now and it save a lot of hastle at the end of the build as it allows you to achieve 'slop free' control surfaces

Sam

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Sam,

simply beautiful work!

Not many are bold enough to undertake an Arrow wood fuse build. I'm sure she will be a sight to behold once finished and will groove like no other.

While I understand your engine choice, I feel compelled to mention that the era called for short stroke engines turning an 11" prop. Naturally, Matt's engine choice was the Webra Speed 61 Racing short stroke (RE) as Prettner's engine choice for the Curare was the Speed 61 Champion short stroke (SE). The good news is that if you happen to come across such an engine or for that matter say an Italian brute (which might also be a little more period correct) such as a NovaRossi Speed/13, they will all bolt in place with no adjustment to your mount. They all share a 25 mm bolt spacing on the lug and a 52 mm spacing between flange bolts. The only issue might be engine length as the Speed/13 is slightly shorter than the OS if memory serves. The Webra should be a drop fit.

Whatever engine powers this pup, it's going to be one heck of a classic!

Build on!

David (across the pond in Canada)

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Thanks for the kind comments, yes chioce of engine......unfortunately we only have to drop a pin in the countryside over here and somebody will complain........ Re Webra I was out bid on one of these motors not so long ago and was disappointed because it would have been nice. But in saying that Redshift is more than equal to any engine of that era and it would have been nice to have fitted my intended engine choice as it is from the very same era.

Enjoying the build and if memory serves me correct Arrow is equally as challenging as Magic but not as technical

Sam

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Sam,

well, the good news is that the RF-P on a good long stroke 10cc pipe will be almost as quiet as a four stroke . Prop it up and keep the RPM's under 11K. It should do quite well on an APC 12x10 or 12x11.

Say, how do you deal with the finishing (painting) of the exhaust box for the diverter that you are using? Do you glass that as well and manage to get primer and paint in there?

I'm actually in the throws of finishing up a very similar RE classic design (rather unusual) which uses the same upright engine and pipe layout as the Arrow and have been throwing around the design details in CAD at the rear of the pipe. I was considering using a 45 degree tilted former to the front of the rear fixed deck, bore a hole in it which will be fitted with a silicone rand. Likewise on the fuse rear bottom which is sheeted with 1/8" balsa. An aluminum tube would then pass through both and a silicone coupler would join the tube with the pipe stinger. I think this is fairly standard actually but your box struck me as interesting as it effectively isolates the fuse interior from direct heat from the diverter. In my case, I have two CF elevator pushrods in sleeves flanking the aluminum diverter and am somewhat concerned with the sleeves melting under the heat of the diverter. Of course there is also the issue of heat dissipation from the diverter which really has no where to go if the rear of the fuse is sealed up. I have a top crutch as a floor to the rear deck which has lightening holes in it and so the heat will in principle rise into the deck so I considered making some sort of "heat exhaust" on the rear deck of some sort. If you have any suggestions or ideas on any of this, I'm all years.

Enough of a thread detour. I hope I'm not taking too many liberties with my questions in your great build thread.

David

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Hi David,

I have had no issues with Magic and heat dissipation of the pipe although initially i was concerned that i would get cooling problems because of the restricted air intake. I use a Carbon Bolly EQ63N pipe and have suffered no such issues with over-heating

A mixture laminating epoxy thinned and micro balloons was used to seal the surrounding area, then painted over the area concerned & fuel proofed in the usual manner.

When Magic was built the plan shows a silicone pipe running through the fuzz and exits on the underside (likewise the same with Arrow). I remember at the time i did not like the idea because i believed over time this would cause problems with fuel / oil ingress resulting in structural failure because most epoxy resins are thermo plastic not forgetting expansion & contraction under heat i believed the joint would eventually fail resulting in problems. This was when i came up with the simple solution of a duct and making it an integral part of the fuselage.

The trouble with this idea was that you have to know the length of your pipe set up for your particular choice of engine. once you have established this you can find the exact position of the duct and build it into the fuzz.

As a starting point the internal dimensions of my duct are 1" x 1 5/8". Making it rectangular allows for slight pipe length alterations.

On my tuned pipe all i use is a silicone exhaust deflector plus a length of 5/8 bore Aluminium tube and a further length of silicone tube cut to suit. I do this, so the Aluminium tube does not come into contact with the duct and rattle. The reason I use over sized tube is simply because it prevents creating any unnecessary back pressure...See Image bellow

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Simple yet effective.

Sam

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  • 1 month later...

Wing cores skinned with competition grade balsa and awaiting LE / TE and wing tips gluing on

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Finished wing panels ready for Ailerons cutting out and retract / servo wells.

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I would like to add that Steve Dunnings Wing & Tail cores are of the highest quality for lightness & accuracy.....

...A big thank you Mr Dunning Esq

Sam

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The next stage is to cut out the Ailerons / Flaps and face with 1\8 & 1/4" Balsa The same method was used as the construction of the tail plane

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As always measure twice and cut once always produces good results. The final stage is to sink a 1/32 ply gusset into the wing tips using a Junior Hacksaw blade at 45 Deg to the wing. (As per same method used on the tail plane)

I always do this as it simply strengthens the tip and prevents the dreaded hanger rash

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Sam

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Finally i have got to the stage i wasn't looking forward to doing and can't put off any more.

I thought my days of cutting out retract wells was long gone due to current trend of 2m Pattern ships. Anyhow, the time has come to revert my preferred tried and tested method of installing retracts into foam wings.

You may find it boring but i will give you a step by step procedure of manufacture and hopefully you may find it useful for future reference.

1st stage is to determine the position and size of the Well

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Using the plan as reference I then Draw out a template

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The template allows for the lining of the Well with 1/16 balsa and 1/2" Sq Beach bearers.

The 2nd Stage is to mark out the template in position onto a piece of 6mm Mdf cut to the same size of the wing panel shuts

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Template with Bearers in position

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Template with Bearers removed

The 3rd stage is to position the Mdf template onto the wing panel mounted in its shuts. Ensuring that the panel is in the correct orientation

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4th Stage is to carefully measure the depth required and set the Router to the determined length by measuring from the top of the Mdf board

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Wheel well routed to depth. Next step is to Rout out the bearers

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The bearers are routed to a shallower depth

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Finished wing panel ready for Lining etc

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If you look at the Mdf template you will notice 2 slots cut into it. These slots are for the 1/16" ply webs that will be sunk into the panels.

To be continued

Edited By Sam Wragg on 12/01/2015 17:59:23

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i Sam that was a very informative thread on the wheel wells and i learned a lot , thank you

Do you have a picture of the router you use, i used to use them on fitting kitchens but they were all big powerful tools

Superb building by the way, even got me interested in the clasic aeros

Tony

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Hi Tony,

Thanks for the complements and I'm pleased you find my method of construction useful.

Regards choice of Router.....its just an industral router probably the same as you use on you job the secret is the cutting tool.

Basically it's a long reach bit (12mm dia) with a bush/ bearing thats the same diameter which locates on the shank. The Bush simply follows the pattern which in turn replicates the exact shape of the pattern.

Hope this answers your question

Sam

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Hi Tony,

Thanks for the complements and I'm pleased you find my method of construction useful.

Regards choice of Router.....its just an industral router probably the same as you use on you job the secret is the cutting tool.

Basically it's a long reach bit (12mm dia) with a bush/ bearing thats the same diameter which locates on the shank. The Bush simply follows the pattern which in turn replicates the exact shape of the pattern.

Hope this answers your question

Sam

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I agree Sam, this is a very informative thread and exceptional quality.

Can I ask a couple of questions?

How do you get the Gorilla glue to spread thinly over a large area? Is it warmed up a bit then just spread or is there a trick?

Also, I have an old kit to build where the veneer has split and lifted off the wing cores. This is new and unbuilt but it's been in a loft for many years. I need to re-skin the cores with balsa BUT I don't have the full foam blanks. Is there a way of re-skinning without the blocks the cores were cut from????

Thanks

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