Irvine .53 (Davis Diesel)

By Martin Bender (Just Engines and Davis Diesel customer)

I've always loved diesels, having worked on the big stuff (Marine engines) for many years. I just prefer them, but with the demise of many (most) of the model diesel engine manufacturers, and the discontinuation of many (most!) of the model engine diesel variants eg Irvine, I have for the last few years been converting my glow engine range to diesel using the excellent products provided by Bob Davis. I have many of his conversion heads - from an Irvine .53, right down to an O.S. Max .10, stock O.S. carb with muffler pressure in a little vmar Cub. This flies at the local field close to home (normally used by electric fliers) and is very-very quiet on an 8x4 prop.

I had the pleasure of meeting Paul and Jenny Landels and family here in Florida where I reside during October 2001. I invited Paul to a day of flying "in the Wilds of Florida", mainly the Flying field of the Flying Gators which is an Ultra-light flying club where some members hop out of their ultra-lights and fly their rc aircraft. It was windy (paul; this is normal in the UK! "quote"), and Paul flew the VMAR Hot rod a high wing with a sym. airfoil. powered by a "just engines" Irvine 53 with a Davis diesel head and stock 'jetstream' carb. as provided with the glow engine. A carb with an 8mm venturi I hasten to add!!. On the front an 11x8 wood zinger prop (paul; your running pressure from the muffler "quote") "yes" and using a check
valve to maintain it" (paul; we British don't do that with diesels) "I do". Sure you get a little discoloration in the tank from the exhaust , but no harm. 
Engine performance is outstanding.... great transitions and never missed a beat. I have a Irvine 46 set up the same. I also have several Irvine 40 diesels that are now out of production that run very well, however the new Irvines with the Davis heads run circles around them. Yes you have to crank them up with an electric starter when cold, and they settle down after a minute or so when warmed up (this is also true of large diesels too). 

In closing the new (Mk3) Irvines with Davis heads run  real fine with tank pressure and the supplied jetstream carbs. I use a one way valve as an option - but don't do that with many of my other Davis converted engines. Its a personal thing.

I hope to write a full review for RCM very soon on the .53 with Davis conversion that will compliment nicely the full report done earlier this year in RCM of the standard glow version. I'll let you know how it goes.

Martin Bender Winter Park Fl USA

end notes; Paul Landels (Just Engines)

It was really nice to be invited to fly when on holiday this year in the USA. I followed Martin's instructions and turned up at the field early (a joint full size and model flying field) with clubhouse, decent toilets, a fridge - and I even noticed a permanent barbeque out back!! Crickey - you U.S. modellers do it right. Come and fly with us 'poor cousins' in the UK on one of our farm fields one day - and see how fortunate you are!!

home of the 'Flying Gators'!

I turned up in T-shirt and shorts and was warmly welcomed by the club members all wearing what I would consider to be winter clothing!! Sure there was a breeze - but I was on my summer holiday!!

Martin had been kind enough to prepare a mode1 Tx. and his Hot Rod thing - which to my surprise was powered by a Davis diesel Irvine .53. Honest..... this was NOT pre-arranged.

I made a few comments........ but in the main, stayed quiet (interested to see how things are done on the 'other side of the pond') and left Martin alone to prep. the model......

(Configured with a standard Irvine .53 - running its standard large bore 8mm jetstream carb - with no restrictions on operation - so it opened to full bore - a super quiet silencer (muffler), with silencer pressure (see picture above - which is why I left it full size) - and an added one way valve.)
He fuelled the tank, backed off the compression probably 1/2 turn, primed the carb. and then 'hit' the engine with a 12v starter. (A real 'no no' as we 'Brits' would say).

The engine started instantly!! Martin then left it to warm up for maybe 30 seconds, adjusted the compression and main needle for max. performance, tested the throttling and handed me the model. The flight itself is not subject to this report!! - but keeping to the engine....... it throttled like a glow - produced bags (LOTS) of power (11" prop with loads of pitch used I think) and sounded really nice. It took off - or should I say 'departed' in quick style.

Will it manoeuvre like a glow?
yes - stall turn, loop, roll, even a very rusty rolling circle and never missed a beat.

It'll never prop hang (you need serious throttle response for that)!
yes - it did!!

Was I impressed with the 'Davis way' of doing things?
yes

As a Brit. I was 'brought up' never to use silencer pressure or electric starters on diesel engines. I was 'Forced/Trained' therefore to use smaller bore carbs (for use with suction - not silencer pressure). A typical 'British approach' - and one taken by the other British engine reviewers.
I have only therefore used diesels in test rigs - to make sure the stuff we sell works - and 'appropriate' models; trainers - scale stuff, when I thought a 4 stroke too expensive, etc....

Does my holiday and first hand experience of the 'Davis way' change my mind?
Absolutely!!

Thanks Martin