My latest gem

[David perry 1]

Ive recently made a small collection of older 4 strokes i intend to pop into the airnin the coming months.  This is sooo sweet and dropped through  my door today.

[john stones 1 - Moderator]

Nice engines David, what's it going in ?

 

[David perry 1]

My son asked the same question.  I hve no idea...anything to show off the engine!  An SE5a would be nice...but thereare so many nice models.  Any ideas?

[Gunnar Borseth]

Download the plan from Outerzone. The Lazy Bee can fly so slow and low you can show off the engine both in the air and on the ground🙂

[David perry 1]

Hi Gunnar

Thanks for the thought but thats one design that leaves me cold.  Thats a pretty one though!

[Outrunner]

When I used to fly ic my Junior 60 had an OS26 FS, just the right amount of power and sounded nice and you could admire the engine.

[Engine Doctor]

Hello Dave. Before using it check the bearing for rust. Its old and if its been stored poorly there is a good chance that the bearings are rusty and the little end  bush is gummed solid. Very s8mple to check . Just remove back plate and cam coverto check for corrosion. Bearings and piston ring still easily available but other parts difficult if not impossible to find new. A stitch in time and it will run for years.

Good luck and enjoy .

Edited June 3, 2023 by Engine Doctor

[Jon H]

I have one of these too, picked it up a few months back. its a lovely little engine and enjoys the much mentioned laser 5 fuel (15% oil). I am toying with the idea of fitting it into one of the DB 20E class models as i had a tiger moth that size years ago, the green air one, and it flew fine on an ASP30 fs despite being quite heavy. From DB you have a choice of a tigermoth, a standard moth or a Pup. 

 

 

[David perry 1]

Tiger moth sounds fun

[Jon H]

In stock https://www.dbsportandscale.com/tiger-moth-e-6525-p.asp

[David perry 1]

Thanks Jon

 

On further review of the site i rather like the Pup.  As it happens ive got the Ju88 to get off the bench -very close now- and then a brand new Galahad to build, which i am really looking forward to.

 

I think the Pup will be the one tho, in due course

 

D

[Peter Christy]

I've got an original OS20 FS in my collection. I've owned it from new, and used it in a Flair Attila with reduced dihedral and ailerons. The power was quite adequate swinging a 10x5 prop, and it both looked and sounded like a WW1 aircraft.

 

I mounted it inverted, but had to move the tank to the floor of the fuselage to avoid flooding. Once that was done, I never had any problems with starting it inverted, though I was always careful to check it for hydraulic locks before applying the starter!

 

The original Attila bit the dust some years ago when I deliberately crashed the model to prevent it drifting over the nearby railway lines. The radio had gone intermittent - later traced to mildew build up on the circuit board - and rather than risk it ending up on the tracks, or worse, I ditched it.

 

I have another Attila kit awaiting its turn on the building board, and the 20FS will be going in that - eventually....!

 

(So many projects, so little time....!)

 

--

Pete

 

[leccyflyer]

I'm not an engine fan - sold most of mine years ago - but one that I do sometimes wish I'd kept is that old, pre-Surpass, OS20 four stroke, which I also flew in an Atilla. To be honest it couldn't pull the skin off a rice pudden, but it was perfect for that model on one of those glorious warm, calm summer evenings that we used to have, just pootling round gentle chandelles at each end of the field.  It sounded just like a slightly asthmatic sewing machine. My original Atilla was donated to a clubmate, after an unfortunate meeting with terra too firma, but I also have another kit waiting to be built. Lovely model.

[David perry 1]

Theres something very sweet about these old 4 strokes.  I never had an Atilla but they are nice machines  

 

 

[Paul De Tourtoulon]

I had one of them, so much power against my HP .21Vt sewing machine motor,,,😅

[Engine Doctor]

2 hours ago, Paul De Tourtoulon said:

I had one of them, so much power against my HP .21Vt sewing machine motor,,,😅

HP VT range were a technical marvel at how to produce low power output but so nice in a floaty plane on a calm day.

[J D 8]

    Still have my Enya 40 4c open rocker in a motor glider. I was running it the other day at local Star Wars event [ club was static displaying models but engines could be run ] Folk are just fascinated by the tiny rockers and valves working at slow tick over.

[Peter Christy]

My Attila wasn't short of power, but it was very sensitive to the propeller choice. I found it worked best with a surprisingly broad bladed 10x5. It looked as if it should have been far to draggy for such a small motor, but worked really well in practice. OK, it needed a shallow dive to loop it, but otherwise it was the perfect power plant for the model.

 

I would imaging David's 26 should provide plenty of oomph - provided you find the right prop for it!

 

--

Pete

 

[Jon H]

10x5 worked well on my ASP 30 when it was in my tiger moth too. When test running my 26 in the garden i have been using 10x6 apc and it seems to perform well. 11x5 might also work in something slow like a Pup or moth. I probably wouldnt load it below 8500rpm on the ground though. 

[Engine Doctor]

One thing I forgot to add . Make sure its Happy when running, mixture /fuel is good so that its  not likely to throw the prop. One of our members fitted a 26FS into a junior 60 a few years ago. He opened the throttle after a longish slow glide with engine at idle . As he opened the throttle  BANG it threw the prop . The prop nut and washer was trapped inside the spinner but he lost the prop driver and spacer/shim in the long grass. Those parts are probably only obtainable via a second-hand source so be aware.

 

[Jon H]

I have found smaller engines to be very temperature sensitive. The long dive would have cooled the engine and although it might have been tuned fine for normal operating temperature it spat the prop when it was cold. My enya 53 used to do this on the first throttle up after a start unless i held it at half throttle for a good 30 seconds or so. My OSfs 40 would also start to knock under certain circumstances and although it never threw a prop it did sound very unhappy. Changing the fuel to the new laser 5 stuff totally solved the issue in the case of my 53, and while the 40 no longer knocks i can still tell if i have been hammering too hard as it looses power. A quick dive at low throttle cools it down and off we go again. I think it just lacks the surface area it needs to cool when thrashed. 

[Engine Doctor]

Hi Jon . I think all of the older  generation fourstrokes were more sensetive to fuel mix and resultant prop throwing . Whith modern oils and the years of experience gained , most modern FS engines are less likely to throw a prop as easily . 

Also when buying second hand you never know if a head shim/gasket has been left out . I bought an Enya 120 4c in a Stampe. Had it running sweetly on test run idled if for a few seconds then opened it up wot  all ok for a few seconds then bang , prop throw. I had my suspicionss that it had been stripped down before i bought it and sure rnough the head dhim was missing . Re-assembled with new shim and its now a very sweet running enigine.

[Jon H]

Yea my dads 48 surpass threw a prop almost every week. He had a bag of spare nuts in his box so he would keep flying. This was in the 20% castor days. In subsequent years updating the fuel and so on the engine completely lost its prop throwing desires and now, beaten and battered, is still going and sweet as a nut. So perhaps fuel was at least partly to blame all those years ago

[Paul De Tourtoulon]

My Enya 120 4c also threw props, as one of my 2 Saito 100's did, both tamed with a shim.

[Engine Doctor]

1 minute ago, Paul De Tourtoulon said:

My Enya 120 4c also threw props, as one of my 2 Saito 100's did, both tamed with a shim.

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