Flying tips and advice available if needed

Forever, Britain's most cherished Crown Jewel
ESzczesniak
Airman
Posts: 35
Joined: 31 Mar 2010, 17:49

Re: Flying tips and advice available if needed

Post by ESzczesniak »

Ok, now for a stupid question. How exactly am I supposed to read boost pressures exceeding 4 PSI in the Mk.1 (all I've been flying right now). The guage reads out -4 to 4 PSI, yet if I'm reading the manual correctly I'm supposed to set up to 6 PSI for runup test and takeoff. Am I missing something? Thanks.

trawny
Airman
Posts: 20
Joined: 09 Apr 2010, 22:36

Re: Flying tips and advice available if needed

Post by trawny »

ESzczesniak wrote:Ok, now for a stupid question. How exactly am I supposed to read boost pressures exceeding 4 PSI in the Mk.1 (all I've been flying right now). The guage reads out -4 to 4 PSI, yet if I'm reading the manual correctly I'm supposed to set up to 6 PSI for runup test and takeoff. Am I missing something? Thanks.
Hey, ESzczesniak

I think you'll find your answer in this thread.

http://a2asimulations.com/forum/viewtop ... 78&t=24012

ESzczesniak
Airman
Posts: 35
Joined: 31 Mar 2010, 17:49

Re: Flying tips and advice available if needed

Post by ESzczesniak »

trawny wrote:
ESzczesniak wrote:Ok, now for a stupid question. How exactly am I supposed to read boost pressures exceeding 4 PSI in the Mk.1 (all I've been flying right now). The guage reads out -4 to 4 PSI, yet if I'm reading the manual correctly I'm supposed to set up to 6 PSI for runup test and takeoff. Am I missing something? Thanks.
Hey, ESzczesniak

I think you'll find your answer in this thread.

http://a2asimulations.com/forum/viewtop ... 78&t=24012
Yes! I had searched for "boost", looks like "Gauges" would have been the way to go for that search. Guess the consensus is that is has to be guestimated.

Caldemeyn
Master Sergeant
Posts: 1101
Joined: 01 Feb 2011, 11:21
Location: Poland

Re: Flying tips and advice available if needed

Post by Caldemeyn »

I have a question, isn't this bird a little over-powered 8) ?, in the manual the climbing speed is 2500 to 3000 fpm, but i could achieve a +/-4500 fpm climb with boost cut-out switched off and canstant speed prop, almost up to 16000 feet without trimming or moving a stick, 15000 feet in 3.30 minutes, full tanks, no ammo

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: Flying tips and advice available if needed

Post by Killratio »

What average boost, what RPM, what temperature. 3 1/2 minutes from standing start..from takeoff, from 1000ft? Accusim on or off, did you do all run-up checks first or just start and takeoff?

The Spitfire is more than capable of 4500fpm..the question becomes what is it's scrap value after you do that?

As with all high performance aircraft what it will do and what it will do sustained is a completely different matter.

My time just now to 15,000ft full tanks, no ammunition, using all proper technique, standard atmoshphere, from sea level, full run-ups, keeping temps and pressures below maxima, full throttle (no ABCO-O) at 2850rpm and at published climb speed, having an aircraft in perfect condition once there, from takeoff to 15,000ft exactly, 5 minutes 14 seconds. She has a few hours on her but is still in good condition...

Spitfire P7280 with Merlin XII and Rotol CSU, in May 1940 with a skilled test pilot at the controls 5 minutes 0 seconds....

As found with all the months of testing, the engine, airframe and airscrews all perform as close to spec as makes no odds.


Darryl
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

Caldemeyn
Master Sergeant
Posts: 1101
Joined: 01 Feb 2011, 11:21
Location: Poland

Re: Flying tips and advice available if needed

Post by Caldemeyn »

Start from 132 feet, boost cut-out off, boost maxed out, and slowly degrading, as i gained altitude, temp 14 c at sea level , radiator fully opened, realism max, tanks full, no ammo, rpm fully fine, Rotol prop, imidiate start and climb, new airplane, mkIIb, and almost no control input, 3,46 minutes to 15000 feet
I just ''locked'' it at +/-4000 fpm and left it.

I hope, i didn't sound insistently :?: :|, or rudely maybe :oops:

ESzczesniak
Airman
Posts: 35
Joined: 31 Mar 2010, 17:49

Re: Flying tips and advice available if needed

Post by ESzczesniak »

Caldemeyn wrote:Start from 132 feet, boost cut-out off, boost maxed out, and slowly degrading, as i gained altitude, temp 14 c at sea level , radiator fully opened, realism max, tanks full, no ammo, rpm fully fine, Rotol prop, imidiate start and climb, new airplane, mkIIb, and almost no control input, 3,46 minutes to 15000 feet
I just ''locked'' it at +/-4000 fpm and left it.

I hope, i didn't sound insistently :?: :|, or rudely maybe :oops:
It certainly sounds like something may be off. I don't know if any of these might be the key, but:

1. What was your departure density altitude? The temperature (which you included) is the most important of these, but local altimeter and dew point are also determinents. If your airfield was 132' MSL, with the right combination of factors your density altitude could be (-)3,000-5,000' MSL making this effectively a climb to 10-12,000' MSL.

2. What were you maximum radiator and oil temps and oil psi? A Spitfire might be able to climb to 15,000' MSL faster than the record of 5 minutes, but the engine may never be useable again.

3. Did you have any head wind? If you have any substantial head wind increasing airspeed over the wings (and through the radiator), your engine can put less power in to forward airspeed and more power in to the climb. If you using real world weather, you can find pockets with 60-80 kts winds aloft started just a few thousand feet off the ground.

4. I understand your realism was to full, but what about accu-sim? This is part of the Spitfire module and what determines the finer points of operating the engine. If that was off, you can abuse the engine more without the bad that goes along.

5. How about your pilot weight? On my system, the pilot weight was defaulting to 0 lbs/kg. When you consider a full fuel and ammo load totals about 850 lbs (on the Mk.II), a 150-200 lbs pilot is not insignificant in terms of payload.

User avatar
CAPFlyer
A2A Aviation Consultant
Posts: 2241
Joined: 03 Mar 2008, 12:06
Location: Wichita Falls, Texas, USA

Re: Flying tips and advice available if needed

Post by CAPFlyer »

Caldemeyn wrote:Start from 132 feet, boost cut-out off, boost maxed out, and slowly degrading, as i gained altitude, temp 14 c at sea level , radiator fully opened, realism max, tanks full, no ammo, rpm fully fine, Rotol prop, imidiate start and climb, new airplane, mkIIb, and almost no control input, 3,46 minutes to 15000 feet
I just ''locked'' it at +/-4000 fpm and left it.

I hope, i didn't sound insistently :?: :|, or rudely maybe :oops:
And what did the maintenance guy tell you at the end of the flight? Flying with maxed-out boost for almost 4 minutes and maxed out prop RPM most certainly didn't do good things for the engine. I'm surprised that it stayed together at all because running that long should have severely hurt your radiator temps.
Image

Caldemeyn
Master Sergeant
Posts: 1101
Joined: 01 Feb 2011, 11:21
Location: Poland

Re: Flying tips and advice available if needed

Post by Caldemeyn »

Thanks for quick replies :)

To answers :
1. Whole settings were default fair weather
2. Temperatures didn't raise above 110 c in a climb, maybe becouse i quickly ascended, where the air is colder 8)
3. No winds
4. Damages to the engine in sim are off, damage in accusim on
5. 86 kgs
6. Strangely motor in a beautiful shape :lol:

maybe i should reinstall the whole aircraft. Is, by any chance, possible that defragmentation of a disk can do something bad :?:

PS. Now there IS a problem, anyone had an issue of self repairing engine? after a flight i visited a hangar, when i opened the window, immidiately i heard a sound of overhauling, and got a complitely new engine, ech i hate this :) maybe an overhaul button is assigned to keyboard :?:

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: Flying tips and advice available if needed

Post by Killratio »

It certainly does sound like something is off (oh, and no, you didn't sound rude...perhaps I shouldn't write replies at 0100!! I certainly didn't intend to sound rude in reply!!)

As said, the Spitifre is capable of doing what you did as long as you never want to use the engine again or are prepared to risk it blowing up. A Cessna 152 is capable of pulling 5g up into a 2500fpm climb (I've done it) but you can't fly it like that normally or for very long. I am not at all sure you would make it all the way to 15,000ft but on a good day, anything is possible.

Tonight I'll try to duplicate what you did.

However my first instinct would be for you to do a takeoff and climb at full over-boost let the rpm go full fine and as fast as it will and fly until things sound dire...THEN go back to your maintenance hangar and have a look...see if it is wrecked, see if it self repairs etc....

regards

Darryl
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

User avatar
Solareagle
Senior Airman
Posts: 128
Joined: 23 Sep 2007, 17:57

Re: Flying tips and advice available if needed

Post by Solareagle »

With full tanks, 160lb pilot, no ammo, and a 180mph climb I managed to reach 15,000ft with the MkII in 3:55 using +12/3000. Engine was still in excellent shape.

With the MkI I was able to reach 15,000ft in 3:30, but to do that I had to stay in fine pitch and run the engine in the 3600 to 3800rpm range. :lol: Engine was still in excellent shape though.
A man's dreams are an index to his greatness.

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: Flying tips and advice available if needed

Post by Killratio »

Yes, entirely possible using the ABCO-O.

A maximum of 5 minutes will give you takeoff and climb to that altitude before getting anywhere near the 5 min limit. (remembering that the extra boost will not help at all above 10,000-12,000ft.)

Climbing tests, quoted figures etc are for general use, everyday pilots, sensible engine life.

In fact the recommended speed for climb is NOT "best climbing speed" for the Spitfire as the angle was deemed too steep for maintaining SA etc. It was also found that the reduction in nose angle, increase in speed, only marginally affected the rate. BEST climb was around 165-168mph, published climb around 185mph (give or take).

Unlike the famous "1%" aircraft that were/are forced to fly within 1% of a few choice figures, the Accu-sim model is designed to model engine/airframe peformance and then produce a final result. Because of this, you will often find that you can produce many and varied results, just as happens in real aircraft.

OAT is not at all stable in FSX and depending on actual day and starting altitude, finishing altitude, you can find bizarre results and this will also affect engine performance/wear.

I am an old hack aerobatic pilot, not a test pilot, so I get results accordingly. Dudley is a test pilot, instructor and check pilot for a host of warbirds and gets better results again...but as said, in all testing, the aircraft ended up performing pretty much to spec.

One thing I will say regarding engine condition...the Merlin is a high performance engine and as such, seems to fare better when run at higher boosts..provided temps are kept within maxima and boost is not ridiculous.

And one final point....15,000ft is not what the Spitfire is designed for. 20,000ft is the optimum height and even the Watts was designed for 16,000 - 18,000ft. Climbing to 15,000 as a goal in itself will often get a different result than climbing to 15,000 on your way to 25,000ft...because there are different concerns about performance vs engine wear.
Interesting that during testing I found a small diffference in performance and asked Scott about it. In 5 minutes he found a small flaw in the engine and prop...fixed it and not only that problem but a whole raft of other little inconsitencies were cured in one hit...proof that the "engine" performance is very accurate. Choose a performance figure at random, pump in a height/power/prop mixture and test..more often than not the result will be pretty much published figure.

regards


Darryl
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: Flying tips and advice available if needed

Post by Killratio »

ESzczesniak wrote:
3. Did you have any head wind? If you have any substantial head wind increasing airspeed over the wings (and through the radiator), your engine can put less power in to forward airspeed and more power in to the climb. If you using real world weather, you can find pockets with 60-80 kts winds aloft started just a few thousand feet off the ground.
An aircraft flys in the relative wind. The airspeed will not vary (except for short term..instantaneous..windsheer or gusting) with the "headwind". The only difference in performance with wind will be the ground speed. Climbing into a 10 knot wind will give exactly the same fpm climb performance as climbing into a 200 knot wind. What will vary is the distance covered across the ground.


Darryl
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

User avatar
Killratio
A2A Spitfire Crew Chief
Posts: 5785
Joined: 29 Jul 2008, 23:41
Location: The South West of the large island off the north coast of Tasmania
Contact:

Re: Flying tips and advice available if needed

Post by Killratio »

Caldemeyn wrote: boost cut-out off, boost maxed out,
Just to clarify..when the Automatic Boost Cut-Out Override is on/normal/red tab UP, the engine boost is limited to 9lb in the Mk II.

When you say that this was "off" I presume you mean that you were using 12lb boost, at least at ground level until it began to drop off?

Solareagle's test was at those settings, my test (to spec) was at 9lb..not overboost and matches published. Overboost will give the results you got, quite properly.

Darryl
<Sent from my 1988 Sony Walkman with Dolby Noise Reduction and 24" earphone cord extension>


Image

Caldemeyn
Master Sergeant
Posts: 1101
Joined: 01 Feb 2011, 11:21
Location: Poland

Re: Flying tips and advice available if needed

Post by Caldemeyn »

Thanks for a replies, they are very informative, and well thought

As of my situation, FSX failed me last night :lol: , complete reinstall, and results are that i think, any real damage can start only when oil and/or coolant are at high temperatures, 12 lb boost, if you try to hold low temps as much as you can, for example: frequent descends, doesn't really hurt.
After 0.5 hour of flight with constant 12 lb boost in mkII(Absolutely no changes of the throttle, except for a landing , maybe 8) ) , i had an engine in nice condition, but i observed something interesting after that, on another start, when i tried to get the engine as hot as i could and then landed and shut it down, the engine for a couple of moments was fine and then started to wear rapidly, i guess that i didn't give it a time to cool down, so the parts started to deform under the temperature :wink: all cylinders on yellow.

thanks for a clarification on performace on 9lb or 12 lb, i thought the limits published were on 12 lb

new reply

Return to “Spitfire MkI/II”

Who is online

Users browsing this forum: No registered users and 12 guests