DeHavilland Swallow PSS?

[Doc J]

Found this pic of a model from a plan but at best its a "Kinda" - not really close to scale, and the control surfaces are badly designed. Probably flew "OK"

But...Nah...at 86" if you are going to do it, then do it right.

I think I'm settling at about 50" span.

I'm tempted to get my 42-year old "Pilot" 0.5mm antique drawing pencil out. I bought this the first time I went to Japan, when I was 29 years old and still sharpening up wood sided pencils for drawing. I thought it was genius!; and though it has now been replaced with newer versions, I still do.

Fact - EVERY design I have done for all these years has at least started with that pencil, at least for the centre line. Its a bit delicate now but still useable (Like me)

Doc.

 

[Doc J]

Another contender?

Northrop X-4 Bantam.

Actually I like the DH108 a little better. Not quite smuch engine nacelles and a bit more of a proportional fin.

The Bantam has some good control surface areas working for it.

Doc.

 

[Red]

Another contender?

Northrop X-4 Bantam.

Actually I like the DH108 a little better. Not quite smuch engine nacelles and a bit more of a proportional fin.

The Bantam has some good control surface areas working for it.

Doc.

View attachment 17903

One of my favorites. If you'd like more reference pics, it's here in our museum.

 

[Doc J]

One of my favorites. If you'd like more reference pics, it's here in our museum.

Woo...I'l remember that - thanks Red.

Doc.

 

[Doc J]

Almost home I think. I'm beginning to make the design envelope - as I do with all my models.

If I do it, Its going to be the DH108 Swallow with the more open canopy and the slightly sharper nose. I know this is a bit of a hybrid, but I wont tell if you dont.

Span/Size
I'm just trying to decide if its going to be 50" or 60" span. I'm tempted to go for the slightly larger span as the performance diminishing scale effects are reduced quite a lot at that size. That would make the fuselage about 1 metre (40") long and just over 100mm (4") wide at the widest point. Taken apart, the model would still be quite easy to transport.

Wing specs:
Wings would be to scale as the area and aspect ratio is pretty good for this application. Aerofoil sections would probably be the Martin Hepperle, or Peter Wick sections but with no washout etc as its not needed. I was tempted to go for the BSLD regime for the wings but with veneered foam cores its a bit hard to do, and also the performance difference would be a bit hard to gauge.

Fuselage:
Horizontally moulded to the ends of the fairings/wing stubs. Canopy (radio/noseweight access) opening with 'drop in' moulded glass canopy Glass and some carbon reinforcement where needed. No panel lines etc as nice though they are, they can make painting a real problem. Jet intakes scale as they are not so large as to be a real problem. 3/4" Hollow carbon or glass round tube wing joiner for balllast, with 6mm locating pins.

Wing construction:
To scale, elevon type control system with some modfication to the control surface hinge areas/volumes to give better response to the particular airfoil being used. Hinges incorporated under the veneer. Hard styrene foam epoxy veneered/vac bagged with balsa or ply over an initial glass layer - or maybe an all-glass layup. TBD. Single servo control surface actuation. No spar probably as its not needed with the wing joiner tube and veneer providing most of the required stength.

Supplied:
Fuse/canopy mould Painted in silver (I have to check that) Wings bare/trimmed hinges freed, and lightly sanded as bagged.
Accessories; Wing joiner.

Its got to be really cheap to make, or else nobody will want it.

What do you guys think? Any suggestions?

Doc.

 

[Mucksmear]

Bigger is better I always say, unless it's a transport issue, like "I got to be able to carry it on my bicycle".
I have a copy of Aircraft Archive Postwar Jets Vol 3 which includes a number of fuse cross sections and elevation/plan detail for both the pointy and blunt versions if you are in need.

 

[Doc J]

Bigger is better I always say, unless it's a transport issue, like "I got to be able to carry it on my bicycle".
I have a copy of Aircraft Archive Postwar Jets Vol 3 which includes a number of fuse cross sections and elevation/plan detail for both the pointy and blunt versions if you are in need.

Hey Muck, M'main man - any information is gratefully received - especially if it can help to generate the drawing.

You are from Kensington? I mean Kensington - as in Royal Borough of?

I am from Kingston Upon Thames - as in Royal Borough of.

Woo.

Thanks for the offer,

Doc (From

 

[Red]

Almost home I think. I'm beginning to make the design envelope - as I do with all my models.

If I do it, Its going to be the DH108 Swallow with the more open canopy and the slightly sharper nose. I know this is a bit of a hybrid, but I wont tell if you dont.

Span/Size
I'm just trying to decided if its going to be 50" or 60" span. I'm tempted to go for the slightly larger span as the performance diminishing scale effects are reduced quite a lot at that size. That would make the fuselage about 1 metre (40") long and just over 100mm (4") wide at the widest point. Taken apart, the model would still be quite easy to transport.

Wing specs:
Wings would be to scale as the area as aspect ratio is pretty good for this application. Aerofoil sections would probably be the Martin Hepperle, or Peter Wick sections but with no washout etc as its not needed. I was tempted to go for the BSLD regime for the wings but with veneered foam cores its a bit hard to do, and also the performance difference would be a bit hard to gauge.

Fuselage:
Horizontally moulded to the ends of the fairings/wing stubs. Canopy (radio/noseweight access) opening with 'drop in' moulded glass canopy Glass and some carbon reinforcement where needed. No panel lines etc as nice though they are, they can make painting a real problem. Jet intakes scale as they are not so large as to be a real problem. 3/4" Hollow carbon or glass round tube wing joiner for balllast, with 6mm locating pins.

Wing construction:
To scale, elevon type control system with some modfication to the control surface hinge areas/volumes to give better response to the particular airfoil being used. Hinges incorporated under the veneer. Hard styrene foam epoxy veneered/vac bagged with balsa or ply over an initial glass layer - or maybe an all-glass layup. TBD. Single servo control surface actuation. No spar probably as its not needed with the wing joiner tube and veneer providing most of the required stength.

Supplied:
Fuse/canopy mould Painted in silver (I have to check that) Wings bare/trimmed hinges freed, and lightly sanded as bagged.
Accessories; Wing joiner.

Its got to be really cheap to make, or else nobody will want it.

What do you guys think? Any suggestions?

Doc.

Dig it...I say bigger. Bigger flies better.

 

[Doc J]

Mulling the fuse I think it would probably benefit from a nice internal former at the joiner rod tube position, and LE/TE braces across the fuselage to stop any crushing on bad landings etc.

Otherwise its pretty straightforward.

To keep the costs down I'll probably make the fuse plug myself. We don' need no stinkin' CNC mills!

Another thought is to get the foam wings/fin made by a third party. Anyone want the job? Joint venture?

Any more suggestions for the model anyone?

Doc.

 

[jure]

wouldn't the fuse plug be a candidate for 3D printing , giving that it is a non flying part and weight would not be a problem ?

 

[Doc J]

wouldn't the fuse plug be a candidate for 3D printing , giving that it is a non flying part and weight would not be a problem ?

Probably would Jure - but I don't have one - especally so large.

Nice idea though.

Cheers,

Doc

 

[jure]

I have a small one , 8" x 8" x 10" , able to print it in sections , but there are others who have larger printers and also multiple units, and more experience !

 

[Mucksmear]

Hey Muck, M'main man - any information is gratefully received - especially if it can help to generate the drawing.

You are from Kensington? I mean Kensington - as in Royal Borough of?

I am from Kingston Upon Thames - as in Royal Borough of.

Woo.

Thanks for the offer,

Doc (From

Nay, I am in Kensington, as in the unincorporated city of Kensington, in Contra Costa County, California (Northern border of Berkeley, USA)!

 

[Doc J]

Nay, I am in Kensington, as in the unincorporated city of Kensington, in Contra Costa County, California (Northern border of Berkeley, USA)!

I see...well maybe we can call it the 'unofficial' Royal Borough of Kensington then.

Thanks so much for the file, E.

Cheers,

Doc.

 

[Doc J]

I have a small one , 8" x 8" x 10" , able to print it in sections , but there are others who have larger printers and also multiple units, and more experience !

Its a thought. I wonder how much time it would take to make a 40" odd long shell.

Can any of you tech savvy dudes enlighten me?

Thanks!

 

[jure]

I wonder how much time it would take to make a 40" odd long shell.

about 40 hours total print time, but consider that the machine does it unattended.
The only interruptions are for starting each job and removing each one of the sections.

 

[Doc J]

about 40 hours total print time, but consider that the machine does it unattended.
The only interruptions are for starting each job and removing each one of the sections.

Hmm...I think this is something I have to bone up on.

Thanks Jure.

Doc.

 

[Doc J]

This is pretty interesting.

Here is a jet powered model, aparently 21 years old, flying. I'd call it a really bad (irresponsible) place to fly, with the clear danger of distracting the drivers on a busy road at one end so the runway, and those really tall electrical pylons at the other end. Not very smart.

Doc.

 

[Mucksmear]

This is pretty interesting.

Here is a jet powered model, aparently 21 years old, flying. I'd call it a really bad (irresponsible) place to fly, with the clear danger of distracting the drivers on a busy road at one end so the runway, and those really tall electrical pylons at the other end. Not very smart.

Doc.

Fantastic vids! I suspect the road and especially the pylons, might actually be farther away than the video makes them appear. Vid seemed to be zoomed in just a little, but who knows. If I were driving on that road I know I'd want to watch the models flying too.
I was positive the narrator in the 1st vid was going to say "John Frost then moved to Canada and changed his name"

 

[purview]

kinda off-topic, but it's badass...