Every action has an equal and opposite reaction.

[Daddy Bear]

Well if I had any doubts about the fidelity of Accu-sim they are pretty much dashed as of tonight.

I have had a little adventure. A bit of long range flying out over the Tasman Sea. I logged a flight from Wollongong about 40-50 miles south of Sydney, New South Wales, Australia to Wanaka, South Island, New Zealand and I reckoned that 20,000ft was a good cruise altitude. Well? Not quite so as it happens.

There I was, way out over the sea and in essence my dear old Moonbeam McSwine was doing about 220 indicated at 20,000 ft without even breaking a sweat. Nearly 350mph ground speed in easy money! Without breaking a sweat!

Everything was in the green. Everything except my oil pressure. It was creeping over 100 psi and I thought "well this isn't good" I was 500 miles from nowhere out over the sea and the nature of Accu-sim meant that I really did not want to loose this bird, simulation or not. I've been clocking up hours with my 'Wee Bairn' and I didn't want to waste them so with about 600 miles to push I wanted to bring the oil pressure down before that big old Packard built Merlin sprung a leak or worse. So I had to work the problem.

I thought that maybe the oil temperature was a tad low. Maybe I should bring the RPM down a bit? No joy. Bring down the manifold pressure a bit? Still no joy. So then I realised that the higher you fly the lower the outside air pressure. Surely, as I understand it, the lower the outside air pressure the higher (relatively speaking) the inside air pressure. So I thought 'Phil' I thought. 'Phil. Drop your altitude two or three thousand feet', so I did. I went down to 17000 ft and d'ya know what? It worked. The oil pressure dropped almost immediately and settled eventually at about 94 psi.

Later as I descended down over the Southern Alps of New Zealand I monitored the oil pressure and the lower I went the lower the oil pressure went.

Hats off to you A2A. Accu-sim? You sweet beauty.

Cheers

Phil F

[CharlieP51]

Thanks for sharing Phil..well written as well. I really can get into these true-to-life (simulated yes) seat-of-the-pants adventures. It is testimony as well to how immersive the Accu-Sim aircraft can be. I could sense you 'sweating it out' as you manged the problem. Cool beans...


It's JUST a SIMULATION OR is IT ??
Happy SKIES to ALL

[Daddy Bear]

Thank you sir!

Phil F

[Killratio]

Phil,

Nice story, nicely told!


Keep in mind that, with the Merlin, oil pressure that high is no problem at all, except as it regards other problems it may indicate, such as blockages, constrictions.
The Merlins will take anything up to 300psi, so high that they don't even bother to run the gauge up there. So whilst you were right to be cautious, you can just keep an eye on it when it happens in future. Also keep an eye on the oil temp. The relationship between the two can give clues..eg, high oil temp, high oil pressure shouldn't usually go together, if you get this, some problem may be brewing.

OAT and proper oil grade for it, is the main game. Once that is right, the actual pressure should only concern you greatly if it is LOWER than it should be.

Darryl

[Daddy Bear]

Phil,

Nice story, nicely told!


Keep in mind that, with the Merlin, oil pressure that high is no problem at all, except as it regards other problems it may indicate, such as blockages, constrictions.
The Merlins will take anything up to 300psi, so high that they don't even bother to run the gauge up there. So whilst you were right to be cautious, you can just keep an eye on it when it happens in future. Also keep an eye on the oil temp. The relationship between the two can give clues..eg, high oil temp, high oil pressure shouldn't usually go together, if you get this, some problem may be brewing.

OAT and proper oil grade for it, is the main game. Once that is right, the actual pressure should only concern you greatly if it is LOWER than it should be.

Darryl

You know what? I did wonder if it would be okay to just leave it. After all Lots of Merlin engined aircraft would cruise at higher altitudes than that in real life combat conditions. But I felt sure I had read in the manual to keep it below 100 psi. Did I read that wrong?

Cheers.

Phil F.

[robert41]

I have found that the oil pressure, in cruise, will climb if the oil temp cools down from a lower power setting.

[Daddy Bear]

I have found that the oil pressure, in cruise, will climb if the oil temp cools down from a lower power setting.

That makes sense. I did try increasing manifold pressure and RPM as well thinking that it might be better to increase the oil temperature, thereby increasing its viscosity. It is likely it would have worked I think but dropping to a lower altitude had a more immediate and noticeable effect. However, in real life, doing so might not always be practical I suppose.

Cheers

Phil

[CodyValkyrie]

Darryl is exactly right. That oil pressure is quite normal at high altitude.

Another customer asked about this not long ago:

http://a2asimulations.com/forum/viewtop ... 93&t=33991

Cheers mate.

[Daddy Bear]

I might just go and thrash a 'spare' airframe to within an inch of its existence just to see what kind of punishment it can take before it starts to pop rivets.

Cheers

Phil F