Large Model Association Forum

I am just starting to build a 1/3rd scale Spitfire VB.

I have already built a 1/6th scale Spit ( from a Mick Reeves Kit) which flies superbly

Because I already have a full set of plans/drawings for the 1/6th scale, I intend to double up on all of the dimensions, double the thickness of the ribs, formers and stringers and double the quantities of these.
I am thinking of using hard birch ply for the ribs and formers, spruce for the stringers and spars.
And covering the fuselage and wings with 1/16th birch ply instead of balsa. I will cover the tailplane, elevators, fin and rudder with balsa. To keep the tail as light as possible.

I realise that this might be bit of an overkill in strength and that the finished aircraft will probably weigh in at something like 36 Kilos.

This is by far the biggest aircraft I have attempted so I would welcome any comments / suggestions especially about my ideas to double up on just about everything.

Reg Homden

awsome! looking foward to seeing this..,.,.will it be a mkvb,,,have you thought about some of the other marks thats not modeled so much.,.,.,a 3rd scale seafire 47 or a 22/24 spit fits my bill................

Reg

Not wishing to dampen your enthusiasm......but simpley doubling all material thicknesses and altering wood types is not really the way forwards when 'doubling' a 1/6 plan to 1/3.

The flight loads on such a large model are HUGE compared to those on a small 1/6 scale model, so serious thought must be given to the structure as well as material types etc........

From past experience of doing a similar enlargement (80% enlargement of a 100" Douglas Skyraider plan by Nick Ziroli), the methods of construction and structures used in certain areas may not be suitable when 'doubled up'. Considerable redesign was necessary in the wing spars, wing transport breaks, engine box to fuselage joints, wing attachment, fuselage transport break, tail plane attachment, landing gear mounts etc etc......

Your suggestions of birch ply for ribs and fomers with spruce stringers/longerons and 1/16" ply skinning sounds VERY heavy.......my 15ft Skyraider build used a lot of lite ply for rear fuselage and outer panel rib, an almost entirely balsa skinned fuselage and 2mm lite ply skinned wings......though substantially bulkier than a Spit, this model came in at just over 80kg's (though did have a lot of additional detail including sliding canopy and a fully detailed cocpkit interior, 20+ servos, a 400cc 5 cylinder radial engine and 15 underwing hardpoints with ordnance attached)

Food for thought..........

Phil

I think Richard Rawle does a 1:3 scales Spitfire short kit

Thanks guys for all of your advice and suggestions.

Robert – although I said it was to be a Spit VB, being ex Fleet Air Arm, I have decided that it will actually be a Seafire (possibly a 47) with arrester gear and catapult hooks etc.

Phil – you haven’t dampened my enthusiasm, but you have made me realise that my initial ideas probably won’t work. So I have contacted Richard Rawle as he has already built a fantastic 1/3 scale spit and I believe that he does a kit for it. Your sky raider looks absolutely fabulous J

Jason – thanks for suggesting Richard Rawle. I have written to Richard asking him for details.

great news on the seafire.,,.will make a nice change.....good luck with the project...

Any progess on the Spitfire ?

Reg take my advice and listen to Phil.
My own 2penneth is; 3 degrees washout, 28% centre of gravity measured at the root chord, 6500 rpm and plenty va va voom.
Ignor any advice from club members you will be in a whole new equation.
Good luck. Mike.

hi reg,,hows the seafire comming along,,,,for your information i have produced a 3rd scale mk9 spit which has now been moulded & a 3rd scale fuss is avalible,,,the plug is shown on page one of new projects,,,dave clarke has kindly listed it for me,,,this would convert into any of the early seafire variants that were high back merlin powerd,,,,later this week dave or I will post some pics of the fuss for all to see,,,,,its fully detailed in every way,,,,a cockpit kit is also avalible with dash,seat, ect,,once the wing is made good to take a mould from the plan is to offer a lower skin & upper skin in carbon cloth layup but holding all the surface detail with a carbon D box front leading section that the skins will fit into,,,,so the D box over laps the skins by 4 inches to allow for bonding & screwing,,,clearly the lower skin will have the pre installed hard points for the hinges & correct angled mounts for the gear,,,plus the ribs,,,,this is purley in the thought process right now but as shown in the pics the wing plug is done,,,,if anyone is interested in a 3rd scale spit either contact dave clarke or myself,,,,,,,