Rotol prop feathering switches for my Lancaster B2 panel …
5c/1979, 5c/1980, flip up covers 5c/2494

“Spitfire start buttons” 5c/898 or 5c/540, want to exchange for single “Lancaster Boost Coil” switches 5c/543 (Canada) new in boxes 😉

I need to check, but I probably have some of these. If you are coming to Newark, come and visit me by the Hornet cockpit.

.
This is an interesting and ambitious project, and I was wondering how the 60% scale size was reached? without having a set of intended construction drawings and preliminary design weight?

The mark III used 4x 1675HP engines, and weighed 38,000 Lb’s empty, with a span of 104′ and length of 72′.

Obviously the replica will not need to have the structural strength to lift a payload of 20,000 Lb of bombs, and therefore will end up proportionally much lighter than 60% of 38,000 Lb, ie much lighter than 23,000 Lbs.

However ignoring adjustments to maintain aerodynamics, the wing span will still be in the order of 62′ and length in the order of 43′, still a very large homebuilt and large aircraft in anycase?, and therefore requiring a minimum amount of weight even if using modern composites.

The four 150 HP rotecs will provide a total of 600HP as compared with the 60% of 6700HP (4x 1675hp) of the original which would be @ 4000hp.

While the modern construction methods might build a much lighter airframe than the 60% scale weight, the aerodynamics of the Halifax will remain largely in scale, so I wonder if the engines to weight ratio would allow the aircraft to achieve the required performance to successfully fly?

The 600hp of the 4 rotecs would suggest a 1/10 scale replica by empty weight?, and the replica target weight would need to be below 4000 Lb’s to achieve the same power to weight ratio from the rotecs before accounting for the Halifax “shape” and drag aerodynamics.

The 4 engines themselves will account for 1100 Lbs themselves, (4x 275) and so the large composite airframe would appear to need to be under 3000Lbs empty and without engines?

As a comparison, the lightweight streamlined composite constructed Varieze has an empty weight of 760 Lb’s with an engine of typically 100hp (itself @280Lbs), and dimensions of 26′ span and 16′ length, ie @1/3 the size of your 60% Halifax and @ 1/6 the implied weight required by the 4 x Rotecs, on 1/6 of the power, but much more streamlined and aerodynamic.

Is the 60% scale determined by the calculated scale power/weight requirements of the composite construction of the design for its given size and nominated engines, along with loss of power due to drag, or based simply on the scale diameter of the rotec (850mm) to Hercules (1397mm)engines?, which surprisingly is a 0.608 or 60.8% ratio?

all in all a very ambitious project, good luck with your efforts.

Regards

Mark Pilkington

Hi Mark,

… and this is just the start of the calculations! It’s a really interesting engineering/design challenge to scale something down.

Here are some of my recommendations:

If a scale replica of an aircraft is the goal, then I suggest your top priority would be to find an airframe designer who has previously worked on flying homebuilds in the UK, and/or within the frame work of the PFA (Popular Flying Association).

Although having some good full size plans of an original, would be interesting reference, putting a tape measure over both examples at Hendon and Elvington would be my first port of call, if they’ll let you. GA (General Arrangement) drawings are available for most types, but apart from overall dimensions, I would suggest that large innacuracies could result in form and proportions derived.

You might want to contact the LMA (Large Model Association) as I’m sure amid their knowledge pool, someone may have created a large flying Halifax model. It will be easily apparent if this looks right too compared to a small 2D drawing.

If you have a suitable airframe designer on board then starting with the overall shape and dimensions, they will then design the important load bearing structure, flying envelope, select the airofoil, c.g position, systems installation, and weight distribution, etc.

Good luck with your project

I have found several fired corroded .303 shell cases on the beach at Wlaton-on-the Naze in the 80’s.

Are these as likely to have come from aircraft as they are from ground forces practicing?

Provenance

The only way to retain the Provenance of your aircraft, and slow the proliferation of newly appearing re-builds, is not to dispose of the restoration cast-off’s – period!

This ultimately, is the only way you will see the numbers of new rebuilds appearing from no-where, drying up in the future.

Without the pile of unuseable parts/wreckage being traded from one company to the next – “post restoration”, there won’t be anything to hang a project serial around, and commence another “re-build”. This would affect the long term future of these companies, so it obviously won’t happen.

I for one, am more than happy to show my 7 year old son a Spitfire flying overhead more that 70 years since the type’s first flight, and whether they are new or old, they are all still Spitfires!

Very nice. Keep going with this level of this level of quality, and your project will be a good one.

The Hawker Fury (RAF version of the Sea Fury) would actually be my bet. 😎

Cees,

I’m not familiar with the Halifax structure at all, but are there many castings you will require in the cockpit construction. For example, the windscreen frames, or any other mounts?