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December 12, 2018, 05:14:28 AM

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Author Topic: Irvine 36 and irvine 39 dimensions.  (Read 510 times)

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Offline British Victory

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Irvine 36 and irvine 39 dimensions.
« on: November 09, 2018, 14:21:43 PM »
Does anyone know if the stroke on each of these engines the same? I know the conrod is identical but my knowledge stops there.
Reason I ask is I have a heli 39 that I picked up cheap but the crank is totally different from the other 39 I have and the carb is different from the 36s that I have and what I would like to do is use the case from the heli 39 (I've used the liner in a duff 39 I had where the gudgeon pin snapped) with the crank from a 36 and a new liner for a 39 as I will shortly have 3 wot4s to play with and I'd like to put a 39 into two of them, if that makes sense.
there's only one f in RCMF,
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Offline British Victory

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #1 on: November 09, 2018, 16:16:37 PM »
Sorted, the crankshaft has the same part number so I can do what I need to.
there's only one f in RCMF,
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Offline British Victory

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #2 on: November 13, 2018, 22:28:36 PM »
FWIW, the engine dimensions and spec are as follows, 36 bore is 20.5mm, stroke is 18.0mm and the power output is 1.1 ps at 19000 t/m; 39 dimensions bore is 21.2mm stroke is 18.0mm power output is 1.3ps at 17000 t/m.
The crankshafts of the earlier 36, of which I have just one and the later 39 model is identical for the aero engines, the heli engines differ in having a shorter crankshaft nose to fit inside a clutch.
As will be evident the engines need to be given their head to develop their power which is why I've done well with apc 10x5 props.
I have a new piston/liner from sussex model centre (great prices btw) so will have two 39s all because I was too idle to drill the spigot of the 39 carb so it can be secured to the 36 crankcase (39 uses a clamp bolt, 36 uses two 3mm set screws through the boss on the crankcase then through the inner neck of the carb).
I can now get back to the refurb of the 1983 wot4 mk2 and the mods to the design of the later mk3 as I now have two light little powerhouses to fit in the models.
there's only one f in RCMF,
               John


Offline NigelR

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #3 on: November 19, 2018, 12:25:17 PM »
Beautiful bits of kit these.

What kind of revs are you aiming for on the 10x5?

I have a pair yet to be used in anger. Was going to go with 10x6. Possibly on one of those nice looking Weston mini pipes.

Offline paulinfrance

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #4 on: November 19, 2018, 12:54:09 PM »
Yes they are, I bought a NIB .53 for a few bob, but they don't seem to rev as high as an OS, but run forever,, :uk:
Mode 2 THE only way to fly


Offline British Victory

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #5 on: November 19, 2018, 13:19:34 PM »
Nigel, tbh I matched the prop to the airframe so it delivered the sort of performance that I wanted.
I made a mistake earlier, the crankshafts are not the same, the 39 has a larger front bearing so that kyboshed that.
What I did discover was that the 36 that dead sticked (causing my lovely old wot4 to have terminal damage to the fuse) had snapped its wrist or gudgeon pin. This is the second one that has failed in such a manner. I can't think of anything that  I've done to promote this, never had hydraulic lock . What I do know, in both instances, when the pin failed on both it failed on the internal shoulder (where the pin is drilled to reduce weight) on the carb side of the pin. After failure the pin appears to have been shoved forward toward the carb with enough force to push the retaining circlip out which then chews up the forward side of the piston. All the shrapnel appears to have been ejected via the exhaust as I could find no trace of it in the engine (one in a 39, the other in a 36).
ila_rendered
The picture shows the damage that occurred on the 36 piston. The second pic shows the pin and the only circlip.

ila_rendered
there's only one f in RCMF,
               John

Offline British Victory

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #6 on: November 19, 2018, 13:25:35 PM »
I should have added that the pins have been promoted to rocking horse poo status as, whilst I have the noble Nobby of Slough rc chasing a few for me -lovely fella btw and great service from the shop as well, they seem to be unobtainable. I did e-mail just engines but they haven't responded yet.
My fallback position is the drill in pic 1 which will have its shank amputated and used as a solid replacement.
It's probably about 0.0015" too small but if it keeps the engine in service it's a cheap fix.
« Last Edit: November 20, 2018, 12:50:30 PM by British Victory »
there's only one f in RCMF,
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Offline The Saint. (Owen)

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #7 on: November 19, 2018, 14:25:22 PM »
Be careful because the shank of a drill bit is softer than the cutting end.
Electrickery is the work of the devil.
Proper aeroplanes are powered by engines.

Offline British Victory

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #8 on: November 19, 2018, 15:59:33 PM »
Thanks for the heads up Owen, hadn't thought it would be a problem.
However tis but the work of two minutes to temper it especially as I have an infra red laser guided thermometer so will be able to get the tempering temperature much closer to the optimum than in the old days when one checked the colour of the item being heat treated.
there's only one f in RCMF,
               John


Offline British Victory

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Re: Irvine 36 and irvine 39 dimensions.
« Reply #9 on: Today at 00:12:35 »
After a search through my spares box found an original,sexually intercoursed, 36. After a struggle and some severe dremmelling it relinquished a gudgeon pin and two circlips which now retain the new piston to the connecting rod and it is now virtually a new engine. I'm going to swap it for the TT GP 42 in the original mk 2 wot 4 and run it in there and use it for the winter. It bolts straight in place of the 42 with a little bit of podgering the engine mount bolt holes.
there's only one f in RCMF,
               John


 

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