Could someone analyze my flight

[Alfredson007]

If somebody could say am i doing anything major errors here.

So my typical flight goes like this:

+9 outside temp. Winds calm. 100 Octane fuel

I start my MKII, i use pretty low throttle, something above rough. Normal oil grade, oil/coolant 100%. RAD open. Pretty soon i add power just enough the plane starts to taxi. When i am at a take off position, i have around 20C+ oil, 50-60C+ RAD. At this point i check the mags and governor at 2000rpm. then i ease on the throttle, soon the temps are around 30C oil and 90-100 RAD and i take off using around 6 PSI and 3000rpm, i open the throttle carefully. After the lift off i immediately raise the gear, and lower the boost to around 1-2 and reduce rpms to 2500-2600. I do not climb much, i try to gain 180mph. I notice my RAD temps are 105-111C MAX. Soon after i start gradually closing the radiator flaps for normal position and the temperature slowly stabilizes to around 88-95 depending on the speed and outside air temperature. Oil temps stabilize to little shy of 80. I cruise usually with rich mixture, if very high then lean, and with -1 PSI and 2250rpm. That gives me something around 200+ IAS.

Then i start to descent, i usually do that at 800-1000fpm. Manifold pressure is usually around -2.5 PSI, somethines less, sometimes i reduce rpms on the prop, but usually it's around 2000-2200rpm. Depending on the situation i either keep my radiator on normal position or i put it +1 on the shut side. I try not to cool down the engine too fast.

In the final approach, i take the gear out at around 150mph, i trim, i open the rads to normal or +1 open. I add a bit throttle, i raise prop rpm, and on a short final i deploy flaps, add a little bit of power, and then i open the rad flaps, +2 or all the way. I land, i retract the flaps when the plane has settled down on the runway and i cool the engine down with low power and by rolling on the runway, i take a short taxi (rad temps around 85 when i exit the runway) i park it, uncock the fuel levers, let it run just above rough and soon after i put the throttle all the way back, after 3-4 seconds i kill it by using the cut-off switch. RAD temps are little less than 100 at this point.

If somebody read it all the way thru, i'd like to ask, is there something i do _WRONG_. I don't mean fine adjustments, but utterly wrong. At this point i have little over 10 hours and the engine is still original but has started to loose its compression and oil pressure (main bearing will go at any moment).

THANKS!

PS. I am very keen to hear how long engine lifes people have got with their mkI/II.

[pjc747]

Very nice. Looks like you've done a good job in your flying. Did you three-point or wheel land the Spitfire? Three-pointers are best, as there is no risk of prop strike. I haven't been able to guage my engine life perfectly, due to my testing for the review on Flightsim.com required me to wreck it a couple times...

The review:

http://www.flightsim.com/main/review/wop3spit.htm

[Alfredson007]

Very nice. Looks like you've done a good job in your flying. Did you three-point or wheel land the Spitfire? Three-pointers are best, as there is no risk of prop strike. I haven't been able to guage my engine life perfectly, due to my testing for the review on Flightsim.com required me to wreck it a couple times...

The review:

http://www.flightsim.com/main/review/wop3spit.htm

Thanks! If you are right and i am not badly misusing the plane, then i must say i am a bit dissapointed how short engine life these early Merlins had. If that is how they really were, then so be it, but personally i'd love to experience MUCH longer enginelife.

About the landing. 99% of my flights are at very calm winds, so i can easily do a wheel landing, but i try to keep the nose fairly high, so it's kind of hybrid landing, but the main wheels touches the runway few seconds earlier.. I've done proper 3 point landings just once or twice. All i am seeking for is pretty smooth touchdown to a center of the runway.

Great work with the review!

[Killratio]

Alfredson007,

A few helpful suggestions (but you are very close!)

You aren't doing the Merlin any favours at all cruising at such low boost. Cruise at around +4 Boost and rpm low enough to give 200mph, if that is your chosen speed. (around 1800 RPM and +4 boost and take the speed you get is better) The low boost is reducing your engine life, working it too hard...this is a high performance engine designed to be operated in the higher ranges.

Also, descent, I use 2600rpm and +0, +1 or +2. The Merlin really does not like running at low boost. The old addage is LOW revs and HIgh Boost will bring you safely home to roost. Better to use a 1000fpm descent rate and take whatever speed results.

I also suspect you are taxiing too early...you MUST have 15C oil temp or you are caning the Merlin. Why not do your runups at your start position?


When you shut down, run the Merlin down to 800 or 1000rpm and then pull the slow-running cut-out. Don't close the throttle until after the engine quits.

Little things help a lot...the Merlin has a very short service life under wartime conditions...100 hours or so. That was improved to 200 odd with limitations etc but THAT figure was exceptional and there was a LOT of maintenace on the way through.

In general though, your temps show that you are managing the radiator properly...and that is a good start!! As you can see, it is dead easy to manage temps when you use the proper procedures. There is no excuse for boiling the engine..as you have found.

Keep up the good work.


Darryl

[Alfredson007]

Thanks a lot killratio!

First of all i do the runups on the runway for two reasons: i have nose in the wind, and my engine is nearly at takeoff temperatures (more rpm i demand, more oil temp i require). I make sure though that the temp is no more than 90 after the run up and immediately after that i take off.

What comes to the low boost. It is in the back of my head that more boost => more heat => more wear and that low prop rpm and high boost doesn't add together. i'm sure you know why i think this way. I believe you though and try to use a tad more pressure in the upcoming flights!

Anyway. It seems that my cylinders are pretty good, my main bearings failed, as i suspected, but after the new bearings, it is in a "nice condition" again. Maybe i just have to ignore those bearings =)

Out of curiosity: In Real Life, (which is history for me btw!) were those bearings relatively easy to change? Just remove the oil pan etc, without taking the whole engine out and tear it apart all together.

Thanks again... !

[Killratio]

Runups there are fine IF you don't raise the engine above 1000rpm (ie don't taxi) until the oil is at least 15C.

The high boost, low RPM comes from combat considerations and the design of the engine being purebred racer.... High boost makes it easy to increase power very quickly (by increasing revs) without stressing the engine. I hear what you are saying about it being counter-intuitive..but it is designed that way purposely. It is teh difference between a Formular One engine and a family sedan's engine.

When it comes to engine life, the factor which most people overlook (historically I mean) is that no fighter was expected to last more than 100 hours or so...so an engine that could perform at high power for that long and then blow up, was actually an acceptable trade off. The engine of the S6 (the forerunner of the Merlin) had a design life of something like 2 hours at race settings!!


No, the main bearings are a MAJOR job...but Scott has already said that there is a little bug in the wear code on startup and shutdown which is causing excessive wear at the moment..it will be fixed in the update.


cheers


Darryl

[seaniam81]

When it comes to engine life, the factor which most people overlook (historically I mean) is that no fighter was expected to last more than 100 hours or so...so an engine that could perform at high power for that long and then blow up, was actually an acceptable trade off. The engine of the S6 (the forerunner of the Merlin) had a design life of something like 2 hours at race settings!!

That's actually a perfect engine. Strong enough to do it's job but built not overly strong that it becomes inefficient.

[Alfredson007]

BTW a tad off topic but if any of the developers are reading this i would like to throw out an idea for future:

Current a2a Spit uses 1940s oils? It would probably last longer on modern synthetic oils? Right? That as an option would give much longer engine life for us who are interested in flying spitfire as we would have it today, rather than we are in war with it in the 40s.

Also i would hope that Overhaul button would have a yes/no confirmation. Strangely i havent yet done any accidental overhauls but i am sure i will someday. Then i am pissed X-).

Any comments?

[Killratio]

BTW a tad off topic but if any of the developers are reading this i would like to throw out an idea for future:

Current a2a Spit uses 1940s oils? It would probably last longer on modern synthetic oils? Right? That as an option would give much longer engine life for us who are interested in flying spitfire as we would have it today, rather than we are in war with it in the 40s.

Also I would hope that Overhaul button would have a yes/no confirmation. Strangely i havent yet done any accidental overhauls but i am sure i will someday. Then i am pissed X-).

Any comments?

Both have been considered. And yes, a modern Merlin is a slightly different beast running on slightly different oils etc.

When the patch is being finalised I am sure all these ideas will be revisted but development on the P-51 and Spitfire V (amongst others) can't be delayed whilst adding too many new ideas to previous models.


Darryl