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Irvine 53 RPM

Started by rbp28668, July 05, 2006, 20:33:01 pm

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Don't know if this is of use to anyone but I've just been in the garden with an Irvine 53, some 10% nitro, synthetic oil fuel and a tach.
Figures as follows:

Irvine 53, Std silencer, 10% nitro      
Dia   Pitch   RPM
11   7   11220
11   8   10230
11   9   8640
12   5   11430
12   6   10500
12   7   9400
12   8   8370

The figures look believable when plotted in excel (no obvious outliers) despite the **** tach that's difficult to get to lock on properly (at an angle from the front seems to work).

Bruce Porteous


What make are the props?
If they're APC that'll be handy for me - thanks.



Hi Bruce

Windy just beat me to it, as I was about to ask what type of props/plug you used. Personally I'd have expected a tad more on the 12inch sizes, particularly as you used 10% fuel. Perhaps the Irvine isn't quite fully loosened up yet? Or maybe it's your tacho?

Still, it's always useful to have some figures for reference.

Thanks Bruce!
Westmorland Model Flyers (Scratch built models preferred, but artf's if you really must)
Windermere Model Waterplane Flyers


Props are APC, plug is Enya #3.  BTW engine was in a Glens 58 CAP with spinner to suite.  It's been flown quite a bit now so I don't think the engine should be in any need of running in.  For comparison, Just Engines were quoting 10700 on a 12x6 APC wheras I only got 10500.  It was quite warm and very humid today- don't know if that had any effect.

Don't suppose anybody has some power/torque curves for the Irvine to hand?

Bruce Porteous


The changes in air pressure and oxygen content change the performance of engines incredably.  I remember my old days of driving my 850 Mini; on cold misty days it used to go quite well, but on other days is was as flat as a fart!!

If I remember my days at colledge air pressure affects can change the output power by more than 10%.

So your figures of 200rpm down on the reported ideal is nothing.




That's interesting. I began the tuning process on my Irv53 with a throttle pipe. Last readings I got to were 10500rpm on a 12 x 8 APC. Now that's a significant increase!!

Goody, goody!


Glyn R

Interestingly I get the same figures on 5% nitro. Model Technics Irvine formula. :o