Large Model Association Forum

I purchased this project at the Nats in 2017. Having instructed my fellow modeling friends not to let me buy another big project they let me down badly. Its in need of some major TLC and strengthening around the wing area, I am told it has flown on a 150 twin but i have a 250 to graft into it with a reduction drive to swing a big prop similar to my 1/3 Spit set up. The wings are being changed to a 3 piece set up instead of the original 2 piece, a big alloy reinforcing blade has been machined to strengthen the center section and tubes will attach the wing tips. Retracts are started which are very similar to the spit ones I made and tried for size, naturally the legs will not be the same.

The engine has now been modified to fit with a reduction of 2 to 1 swinging a 40 X 26 prop for running in. There are just a couple of small jobs to do before I can run it up one of which is a tie bar from the prop driver mount to the bulkhead.

Hi Dave, is the reduction drive unit manufactured by yourself?

Yes Colin, I have my own CNC business and its one of the perks of the job. I purchased Solid works this year and it has made making these sort of projects a lot easier than when I designed them on the back of a fag packet.

That's good to know Dave.. fantastic looking bit of engineering!
I have a 1/3 scale model which has a 3/1 reduction unit powered by a Zenoah 62.
From memory the scale prop is around 38 inch. The engine is reversed so the prop swings clockwise.
Can a unit be manufactured for most engines? will the bearings need up graded to cope?
Colin.

Not all engines are suitable and in many cases the front bearings can cope, with my Zenoah projects I add a second bearing to give added support due to the crank design.

Hi David,
What is the belt type used on your reduction drive ??
Thanks
Daniel

Envious ! Nice job

Hi Daniel, I use a polly V belt J section and choose the number of ribs you need

I have now made the new tail feathers to the point of fitting new wing tubes as I could not get a replacement tube to suit the existing set up. As fit the engine, this has had a major strip and rebuild. ZDZ seem to be a jinks with me. This engine was new direct from the factory but arrived with no ignition and after several mails I still do not have one. To top it off when I removed the heads to turn them 90 degrees for cooling I found other issues. The pistons were marked on the top where during initial test runs at the factory they had hit the heads, these had been remachined as there are no marks on them. Next I found that the pistons were stroking 1.7mm below the exhaust ports so this was wasted stroke. I have now remachined the barrels and crankcase to get the deck height correct and shimmed the heads to suit. She is now reassembled and ready to test run.

Nice work Mr B!
Cary

Started to get the fuselage ready for the new wing and engine mount. Cutting out the old work was a nightmare of a job but it’s getting there.

Before the wing mount and now, the original was a 2 piece wing but now it is a 3 piece with a center section that will mount as in my 1/3 Spit

The wing is nearly ready and is hanging up ready for the fuz to be sorted, the center part wil be built to suit the cut out in the fuz.

The fuselage is nearing completion of the repair and is looking in better shape ready to receive the new formers etc.

Looking good Mr B!
Cary

It’s a long one Cary

Not as long as Steve's when he starts...…………….. Haha
Cary

Following my request for a new Canopy for my P-51 I was given an offer to purchase the Fuselage, canopy and spinner moulds. The fuselage mould is in very good condition inside after a clean up but needs tidying outside as it has a few rough edges, the canopy mould is broken but repairable and the spinner mould also needs some attention. My first job is to make a few repair parts for my fuselage and wing center section as I feel I have put too much work into it to discard it now, it fitted the mould a treat. Then I will look at pulling complete fuselage’s from it, there is quite a bit of work to do before then in producing the formers and longitudinal supports which this airframe needs if being powered by the new generation of engines available.