Piper Twin Apache PA23 -150 74"

[Terry Walters]

Morale boosted! Fascinating stuff Danny! I used to see one of these at Sywell when I used to sneak round the hangars as an inquisitive lad - it was the only twin there except, temporarily, on Fridays when the Derby Airways DC3 used to stop to pick up passengers for the Channel Islands!

Take a day off next Wednesday but we want you back to work on Thursday!

Terry

[Paul Hartley]

Great stuff Danny. Looks wonderfull and the thread is really useful in covering the different techniques you and others are working through.

[Martin Roberts]

Hi Danny and Ton,

I almost bought Rhino myself some time ago, a lot cheaper than AutoCAD, but at the time I had several versions of AutoCAD, Turbo Cad, ArchiCad, blah blah under my belt, then I changed jobs from building design to working for Council, had to learn 13 new software packages that year and to be honest I couldn't at that time see the benefit of yet another Cad learn - maybe I will have to remedy that - looks like I might have to down load the trial version..... Anyway, onwards and upwards Danny, keep up the good work and remember Santa is on his way hey hey ... Marty

[Danny Fenton]

Thanks guys, glad its all of use and thanks for the kind comments it really does make typing this lot worthwhile.

I used to go to Sywell as a lad too Terry, I used to camp at the PFA rally. I was probably in my late teens I guess so late 70's.

I guess its aircraft of that era that bring back fond memories for me, and why I like them so much. But my heart is still with the warbirds for the most part. Will this twin change all that? I can see a whole host of similar twins, Geronimo, Aztec, Commanche and Navajo to name but a few. Then there are the Cessna and Beechcraft twins of that era the 310 336 the Bonanza and Barron. And one rarely modelled Grumman GA-7 Cougar. Ton sharpen your pencil my friend

Martin if Santa would bring a license for my demo version of Rhino I would be thrilled, but sadly I don't think that is likely

Cheers

Danny

[Tony Bennett]

it is a fantastic build and i am enjoying watching it all come together.

way out of my league though for skill.

[Danny Fenton]

Thanks Tony, I don't think its out of your league at all Tony, I really enjoy your builds, and I wish I could match your productivity!

[Ton van Munsteren]

Posted by Danny Fenton on 20/12/2013 09:19:15:

If you could build in 3D the rectangular section I have missing, then I can make a plug and vac form them. I have heard from Rob and his method is very neat for making the plug.

Cheers

Danny

Hi Danny ,

Sorry but its not clear what you mean.

Cheers

Ton

[Ton van Munsteren]

Posted by Danny Fenton on 20/12/2013 15:39:49:

all that? I can see a whole host of similar twins, Geronimo, Aztec, Commanche and Navajo to name but a few. Then there are the Cessna and Beechcraft twins of that era the 310 336 the Bonanza and Barron. And one rarely modelled Grumman GA-7 Cougar. Ton sharpen your pencil my friend

Cheers

Danny

Okay my Pencil is sharpen so tell which should go first I like them all and don't forget to send a good 3View.

Cheers

Ton

[Danny Fenton]

Lol if only somebody would pay us loads of money to do that. Better get this one right first
Sorry I am finding it difficult to explain my thinking re plug construction.
If you lay the ply window template over the fus thats the section that needs to be assembled on a flat surface. So you end up with a shallow rectangular block, the upper face of which is the entire side window.
I hope that is clearer? If not I will make sections of the bulkheads and stringers involved freehand
Cheers
Danny

[Ton van Munsteren]

Hi Danny,

I do hope Iam correct do you need the surface of the window to make a block to make vacuum part.

Can make for you cross section positive and negative based on a block.

Cheers

Ton

 

 

 

 

 

Edited By Ton van Munsteren on 21/12/2013 14:48:15

[Danny Fenton]

Hi Ton, yes that's more or less it, perhaps add some extra stringers and ribs to make it fairly strong, vacforming can exert a fairbit of force though this wont take much as the curves are gentle.

If we make the box 25mm tall at its heighest point, or something like that?

excuse my rubbishe drawing, the outside size only needs to be as large as the ply template you show in white. I think if the 2mm sheeting ends up 1mm lower than the final surface that will allow for the thickness of the PETG

Cheers

Danny

[Ton van Munsteren]

Hi Danny,

Would that be something to work with every 20mm a former with foam in between would make a good mould

Cheers

Ton

[Danny Fenton]

Hi Ton yes that would be nice and rigid. I could glass it to make sure. Perhaps even just profilm?
Cheers
Danny

[Ton van Munsteren]

Oeps now I see that the pic was not included in my post so here it is.

Will rotate them and send by mail in 10min or so.

Cheers

Ton

[Danny Fenton]

Thanks Ton easier for you to do than for me to explain
Cheers
Danny

[Ton van Munsteren]

Danny, drawing is send have fun making the left and right site plug.

My job is done , now its your turn to do the rest of the work

Cheers

Ton

[Danny Fenton]

Thanks Ton, what is the spacing 20mm between centres?

Looks like I have some cutting out to do

Cheers

Danny

[Ton van Munsteren]

Yes 20mm

Cheers

Ton

[Danny Fenton]

Thanks Ton, one more favor can you indicate where the windows are with reference to those sections. 20mm spacing gives me 320mm plug the size of the ply section that covers the side windows is 280. I might not do the rear window as it is flat to save me some cutting out.

Cheers

Danny

[Martin Roberts]

Hi Dan and Ton, yes you guys are on the right track, nice idea to go with the foam if you were making a fiberglass mould, unless you are skinning the foam with ply/balsa? Either way, I obviously explained well enough for you two to be on the right track... Hopefully Ton has cut the sections to the inside of the fuselage and then take off thickness of balsa or ply skin so that when the window panels are laid on this 'inner skin' the plastic will form up to the inside of the real fuselage. Personally I would be use either 0.3 or 0.5 PETG, at 0.5 thickness the windows would be very rigid but still light, don't forget to trim the ply/balsa windows by 1.5 times the thickness of the PETG all round so that the radius of the PETG (after the forming) has enough room to sit nicely inside the 'frame'...Just thinking ahead Danny, Have we allowed enough on the window cut outs to 'feather' the fiberglass skin into the window openings for a smooth finish and still have room enough ? Marty

[Martin Roberts]

Danny, at 20 mm this would be 300 mm, you forgot the starter with zero thickness plus 15 x 20mm. I have made that mistake many years ago cutting material for balustrades LOL, oh well at least I can weld steel back together - harder in hardwood - Marty

[Ton van Munsteren]

Hi Danny,

Here are some sizes and good thinking Martin

Cheers Ton

[Ton van Munsteren]

Danny,

As Martin mentioned just to make things clear I have taken the outerside of the fuse not the innerside of the balsa. Because I was thinking that you will not use the cnc part and make you own frame to glue the vacum part on fluss with the fuse outersurface. Taking 0,3 or 0,4 of because for the thickness of the Petg material is not needed because that difference will not really show.

Ton

[Martin Roberts]

Hi Danny,

if you import those sections into Turbo and use the offset command at 4 mm, select the line then click inside the line, you will have the cut out (4 mm = 2mm for the outer skin of the fus + 2 mm for the inner (false) skin so that the window cut outs can lie on top) no need to CNC these parts, and if the profiles are cut from 2 mm balsa or ply, the space would have to be 18 mm, 18 + 2 = 20, this is because the 'surfaces' Ton is cutting have no 'thickness' as such just like a piece of tracing paper - Marty

[Danny Fenton]

Hi Martin, thanks for your assistance, yes schoolboy mistake neglecting to factot the end pieces. I have used the offset command in TC many times. I did do a fair bit of the innitial 2D in this drawing As Ton says the amount we are talking about won't make any difference there is only a slight compound curve at the very front of the forward window, so the depth that it sits will not matter. I wasn't going to cnc them, they are simple to cut.

I realised Tons lines had zero thickness which is why I asked Ton if the distance was to the centres

I was also not thinking of using foam, well not in the way Ton has suggested. I am thinking I will sheet this in balsa then fill the backs with expanding foam to fill all the voids. I think this will give the same result.

Thanks chaps, nothing done on the model but a lot done in working out the wrinkles of a solution Much appreciated.

Cheers

Danny