Hispano-Suiza 8F (Part 1)

This is a bit of a departure from my normal fare, but it’s something I’ve had in mind for a long time. A scratch build from original drawings of an aero engine. In this case, a licence built version of the Hispano-Suiza 8F.

Now here things get a bit muddled in precise terminology…

The actual engine I intend to model is the licence built Wright-Martin H3. Which is a US version of the Hispano-Suiza 8F. It bears a lot of similarities to the Hispano-Suiza 8B that powered the Spads, SE5as etc during the First World War. However, the 8F was  increased to 18 litres displacement, rather the 11.8 of the 8B, and differs in many detailed areas when you get into it. It certainly isn’t just a ‘bored out 8B’ as I’ve read.

[The Wolseley Viper fitted to the SE5a was a licence build of the H-S 8B, in its various forms. The Wolseley ? was a licence build of the H-S 8F.

If I’m wrong on any of this, please let me know and I’ll amend this post.]

With the volumetric increase, power output went up from 220 to 300+. The same engines today running on 87 octane petrol (WW1 petrol was 40  – 60) and increased compression develop around 500 bhp, so it was no slouch. Indeed it was ahead of its time and one of the best aero-engines of the war. They became a weapon of choice for post WW1 racing boats as they were plentiful and powerful, which is where I come in: I want one to fit to a number of models I have planned.

I failed completely and utterly to find any kit of the F version of the H-S engine, let alone the H3, and the CAD models available on the net really don’t cut the mustard. At all. So…

Deep breath, and go for it: Do your own…

I started off by copious research and downloading pictures and drawings of the H-S engine off the net. The Smithsonian website has some excellent pictures of a Wright-Martin H3 engine. There are also some drawings by a modelling magazine of yesteryear (Air Age Inc) which look promising at first sight, but if you are modelling the 8F/H3 engine, run away. Very  far away!

I spent 4 days trying to turn them into an 18L CAD model, but the dimensions given, vs the images,  just don’t add up. After head scratching to the point of baldness I threw myself upon the mercy of the internet.

Yeah, I emailed a few complete strangers…

Now the modelling fraternity is full to the brim with enthusiasts who just want other people to enjoy what they do too. Luckily one of the chaps I tapped for info came up trumps (thank you so much Keith), and emailed me some very clear drawings of specifically the Wright-Martin H series engine. Rum-ching, get in there!

I’ve subsequently discovered the drawings come from…

Wright-Martin manual Cover

of which I’ve managed to obtain an electronic (AKA dodgy scanned) copy.

So I was off… I’m not bad at CAD, even though I’m self taught, so I started tapping the keyboard and shaking the mouse.

First up was the crankcase, which I was desperate to get right as it is the heart of the beast.

So I went from…

after several days work…

to…

Crankcase Screen shot Cropped

I’ve been searching for a decent bunch to print out these designs in 3D, and so have been in touch with a number of companies. I’ve given up on my first choice (see previous post) and so tried some other people. GoPrint3D offered to send me a sample print of a section of my design, and they appeared to care about their customers, so I agreed with alacrity.

20200326_174156

I was involved with 3D printing from the outset over 20 years ago, but it is still slightly surreal to see the parts you have designed, purely on screen, made real.

While there are still some issues around facets appearing on rounded surfaces (which may be a fault at my end I suspect) the print is eminently useable for direct incorporation in a model after smoothing, or as a mould master for casting.

Since I sent the file off to be printed I have continued to develop the CAD model. However, there seems little point in putting up countless pictures of a growing CAD design, so here is one showing where I am at the moment.

The picture comprises about 100 hours of work for those who want to gauge the effort required, and that’s already being quite familiar with the software.

In Progress Engine No.1

The idea is that this engine will appear in a number of vintage model boats that I hope to build.

9 thoughts on “Hispano-Suiza 8F (Part 1)”

    1. I can see it as a possible future of model making. When 3D printers of high enough quality become ubiquitous, some firms will sell ‘kits’ to download and print. It will be a long time before printing can match the quality of injection moulding though.

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  1. Nice one. As per PM I built the 8e from scratch. Mostly because I wanted one for the 1/24 scale SE5a I made and there is nothing on the market. Having managed that I decided to make one to partner my 1/8 scale Hassi Gnome. Not gone to such lengths as you have. As always you leave me standing. 🙂

    The thing I found out about the aero-engine 8b~e was that the reduction gears on the front were its weak point and would often shatter or jam resulting in some interesting scenarios for the pilots. The British built version, the Wolseley, was a better success due to an administrative error. They didn’t think the license included the reduction gear so didn’t make them, instead of fitting the prop directly to the crankshaft. Turned out more reliable, and fitted to the SE5a (4 blade prop). You can tell which had which simply from the radiator and where the prop shaft exits. If the bottom of the radiator it’s a Wolseley, if near the top it is a Hissi.

    Anyway, as per PM, offers to save money and try printing any of the parts for you is on the table. Looking forward to this build, mentor.

    Jon

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  2. I’ve been doing the cam covers. 95% was done in a couple of hours. The last 5% has taken 2 days. The shape at the rear is very difficult to model. I wasted a day trying to solve it the wrong way, but had a vino inspired brainwave last night. So I spent today working that through. It should’ve been a few hours, but somehow the CAD model got corrupted and that took me an hour or so to work out. I thought I’d done something wrong, but I hadn’t.

    So I ended up scrapping this morning’s work and redoing it, without fault this time. So I think the camcovers are done. I just need to finalise the vertical cam drive tube at the rear and the cylinder banks will be done.

    Then I might do an exhaust for light relief. They are just tubes at various angles.

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      1. Thanks. After much frustration, I am rebuilding my printer from scratch and will try myself. There is no reason why a pro can’t print it, they’ve done it before with finer detail. There have been other things too. Catch up later, but thanks 🙂

        Liked by 1 person

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