Would I have survived?

[teson1]

Ok, I pushed the engine (or the sim model?) of the L-1049G Connie way beyond typical realistic operating conditions for the Evita event...

In particular I flew with much leaner mixture than recommended:
- approx. 30-40% lean (recommended 10% lean with low blower), and
- higher MAP than recommended: 48-49 psi (recommended not to exceed 43 psi with low blower as per the handling notes http://www.flightsim.com/file.php?cm...ame=L1049G.ZIP).
See other parameters below.
These operating parameters resulted in -30% fuel consumption compared to AutoLean mixture setting.

After reading a lot on realistic flying during the event I am having second thoughts.
I guess the more one knows on how and why the real planes are operated the way they do, the less fun there is to operate the sim game-style...

Now, I wonder about the following:
Is it in principle possible to fly the way I have with the real plane?
Would I (and the plane) have survived the trip?

+ What would have happened to the engines?
- Would the engines have worked at all with very lean mixture?
- Would the plane have arrived at all at a leg's destination or would the engines likely have failed in flight?
- Would the engines (and other parts) have to be changed after each leg?

+ Would the real plane have behaved the same way regarding fuel consumption/speed, or is it a quirk in FS that consumption decreases so much with very lean mixture?

I mean would it have been possible that a participant to a real-world race would have flown my way, and arrived, scoring similarly? Even if this would have required installing a new set of engines at every airport and any spare part needed, unlimited money, was willing to take risks - somebody who would _really_ like to win... (who, me? Hehe... :d)

I would appreciate your insight. Sim or game flying?

Thanks,
Gunter

******

Below are the parameters with best speed/fuel efficiency determined by test cruise flying.

Plane: Lockheed L-1049 Super G - Jahn et al - flightsim - l1049g.zip with update
http://www.flightsim.com/file.php?cm...ame=L1049G.ZIP

The parameters were optimised to provide the best "score" (speed/fuel consumption) in the frame of the Evita race rules:
Total score is flight time + 0.3 hr for each 1000 lbs of fuel consumed.

Main observation was that speed (power) for a given altitude is determined by a given set of RPM and BMEP (which is realistic for this type of engines as far as I understand).
Fuel consumption was the lower the leaner the mixture (the higher the MAP to achieve a given BMEP).
So best score was obtained with maximum permissible MAP (49 psi, end of green arc, for the model, as higher MAP may have resulted in failure of the modeled engine AFAIK).

Altitude = 10000 - 12000 ft (actually, cruising higher resulted in lower scores. With critical altitude = 10500 ft, MAP available was below 49 psi, i.e. needing a richer mixture and higher fuel consumption)
Low blower
2500 RPM (green arc)
BMEP = 170-180 psi
MAP = 48-49 psi (end of green arc)
Mixture = very lean (14-16%)
The mixture was leaned so far that with a MAP of 48-49 psi (end of green arc), BMEP was 170 - 180 psi.

This resulted in a TAS of 260 KTAS (approx 220 KIAS) and
fuel flow of 610 PPH/engine (2440 pph).

With AutoLean Mixture setting for comparison:
Mixture = AL
MAP = 34 psi
FF = 960 pph/engine
All other parameters (RPM,BMEP,TAS) same.
Fuel consumption was reduced by 30% by leaning the mixture.

Btw, the Composite Cruise Control Chart of the real plane, included with the handling notes gives the following parameters for cruise at
12000 ft
115000 lbs
220 KIAS
high blower (no chart for low blower):

2500 RPM
BMEP 180 psi
FF 840 pph/engine (3400 pph)

[Dangerousdave26]

There is a strong possibility you would have survived.

If once you blew the first engine you backed off the throttle and played it safe you could have landed safely.

If you would have pushed the three remaining engines until failure No you would have been Toast.

For the Record McHales Airlines ran the Northstar / Argonaut at the published numbers in the referance pages.

[Moses03]

We had conceived this event to fly the propliners at published specs. Unfortunately not everyone did this. (Gunter, I'm not picking on you directly.) It was a great turnout and kudos to those who completed the race but in the end it was unfair to those who ran their entries within normal real world numbers.

I hope sometime in the near future we will have a Duenna type program that can monitor engine map & rpm for these types of events. Maybe even check to see if you dive down to the ground exceeding fpm for that particular aircraft. You would then be flagged with errors accordingly. My opinion of course. I would also like to see the RTWR race be flown more realistic someday instead of 90 minutes of firewalling your late war fighter.

[srgalahad]

In general, it's possible to run 'super-lean' mixtures on some engines. Long-range patrol missions during and after WWII proved the theories (notably Catalina flights of up to 24 hours) but the precise numbers were initially found by trial and error. A P&W engineer could probably pull a file to give absolute numbers for a given engine/airframe but I'm not sure FS, with it's limited model would prove too realistic. Some basic information may be found here:
http://www.lycoming.com/support/publ...fs/SI1094D.pdf

On the subject of altitudes, FSRTWR history shows that in non-supercharged engines the efficiency loss of operating slightly above "critical altitude" - lower power and related loss of speed - is compensated for by better winds aloft (for longer periods). Tossing two-stage blowers into the mix raises new questions, but the 1049 was designed to operate in the range of 17,000' to FL230 on long flights.

Advanced system modelling like that in the A2A B377 brings out some of the other issues (cooling, etc.) but the basic FS model is limited. In most cases I'd say that the published numbers have been tested to be the optimum (if taken from the real world stats) to balance performance with engine life and costs (fuel vs flight times vs maintenance).

Rob

[3/7charlie]

Over Lean mixture will push the CHT up up up, and you will cook the engine. An accepted practice is to lean out the mixture untill you show EGT(if you have one) rise, then nudge it back towards rich. As altitude increases, air density drops, so the mixture needs to be leaned out.Over rich mixtures give lower temps but foul the sparking plugs. One can monkey with the mixture some from the book settings, but the mixture/MAP/RPM/Fuel flow graph has been arrived at by many,many years of trial and error and hard won experience. I have read several accounts of P-51 drivers getting home with cooling systems shot out by running full rich,and stroking the Kholer pump(manual primer) every 4-5 seconds to over rich the engine, keeping the temps just under the red line.It would run like crap, as the plugs fowled, so you quit pumping for a few moments to let the temps climb and burn the lead off the plugs. Don Gentle wrote that, after 2 hours or so of contiuous pumping nursing his Mustang back with a shot up rad, that he had worn the thumb out of his glove, and then wore the hide off his thumb down to the bone, the cockpit looking as if a hog was slaughtered in it, but that was preferable to being a POW.

[teson1]

Dave, kudos for the excellent performance! Mc Hales is the real winner in this event. But that was clear from the beginning, in view of McHale's mileage.

Moses,
I take your point, and maybe I have not read the rules sufficiently in detail, mea culpa.
A big part of the interest in the racing for me is to squeeze the best performance out of the plane, find a sweet spot with best performance.
Now, another big part is keeping everything as realistic as possible.
Seems I have veered way outside of the realistic envelope here.

Blame this on my lack of knowledge on what a real plane can stand and what not. But learned a lot (and that's another part of what I love about FS!).
Here's my trophy back!
Now I'll crawl back into my hole. :toilet: :d

srg, now that is very interesting information!
So it seems I have shamelessly exploited the limits of FS.
Seems at least the engine should run rough with very lean mixture. Tsstssstsss, seems we need a new sim...

[Moses03]

Gunter- Please keep your trophy! I'm just a bit grumpy at times about sim-style balls out racing vs real world flying.

We had encouraged everyone to fly by the numbers but it was not a rule. This race was a good measuring stick for future events. Especially with the payload management.

Hopefully everyone had fun with it one way or another.

[srgalahad]

Here's an interesting series carried on AvWeb-
Pelican's Perch #63:
Where Should I Run My Engine?
http://www.avweb.com/news/pelican/182179-1.html
http://www.avweb.com/news/pelican/182176-1.html
http://www.avweb.com/news/pelican/182583-1.html
It's involved, sometimes technical and rather lengthy but worth a read.
(note: it's written for injected engines and there are differrences for engines with carbs.)

One thing to consider is that not all models have fully functional CHT gauges etc. so it's hard to follow complete procedures.

As for 'exploiting' the limits, the way I see it, in the interest of not "over-legislating" the event, the committee didn't specify every parameter so there naturally would be some accidental or intentional fudging. A lot of that was balanced by the calculations used. To be as precise as possible would also require a sim that enabled all the functions of a r/w aircraft and we don't have that, nor do we have perfectly modeled aircraft. For example, are the #s for the NorthStar perfect? We have to depend on the info published and what we could test.

In the McHale case, we tested almost all the listed aircraft and looked at the rules. The significant advantage of operating at FL250 with strong westerlies and the tested fuel burn gave us an indication that it would be significantly ahead of most of the fleet that had to fly low, so we purchased the surplus NoisyStars and set off. We also had a set of fuel consumption tables (from testing) that gave us predicted loads to be used based on the forecast, or observed winds and which were within about 10% of what we got on the legs. Sure it was a fair bit of work, but that's what it takes to run a successful airline . We also tested performance "beyond the book" and found there was little to be gained in the case of the NorthStar and risks attached. (Yea Jens!)

Rob

[Dangerousdave26]

In the McHale case, we tested almost all the listed aircraft
Rob

Time wise I am inclined to believe we had more time invested in testing and preperation for the event than we did flying the Race.



I flew each plane to each set of published numbers "High Cruise" "Fast Cruise" and "Economy Cruise @ varing altitudes to test the speed and fuel consumption of each aircraft. That is excluding the A2A 377 which I do not have.

That alone took days and was likely what fried my video card.

Then once we decided which aircraft to use we needed our own Paints. There goes another week of work.

Now the rules come out and we find out about this %^#%#&^% Payload Bonus. Which could have been the great fuel efficiency equalizer.

[Vicious]

You can count me in the group with Teson that squeezes every ounce of performance out of the flight model without much regard for what the actual aircraft could perform. I simply took the data that was provided by the committee, downloaded the various models and tested to see which gives the best performance for the desired route operating under the rules in place. This is what I do for the RTWR so it seemed applicable here, although apparently some may see it a bit differently. However if there were an unenforceable rule to fly to certain engine parameters, much like the no GPS rule, I would honor it of course.

Sorry if I frustrated anyone with my interpretation of the rules or perceived fudging. I had fun pushing my aircraft to the limit and navigating around South America once again.

[srgalahad]

every ounce of performance out of the flight model without much regard for what the actual aircraft could perform

That whole issue is what frustrates some of us (or all of us some of the time?) - the flight models are not totally realistic and enable us to get away with all sorts of things. From my discussions with a few builders and FDE guys it seems to stem from having to make compromises to fit the MSFS game engine, unavailable data or sometimes a lack of time/patience/knowledge of how to bully MSFS into doing it "right". In other cases the FDE is simply wrong but thousands of adoring fans would be up in arms if performance or flight characteristics were too "real" and the model didn't perform like the PR guys said it should -- I'll put the Shockwave P-51 in that list. Others, like Gnoopey (P-47) and C. Knoell (F4F-4) have worked hard to model to the real world.

As far as the airliners we ran, they mostly were close to proper numbers for speed/fuel overall, but some do better than others at emulating not 'airline style' flying, but accurate stress or climb/descent values. One example is the DC-4/6 emergency airbrake setup (which was real) that required lowering the main gear as otherwise the airplane would overspeed/overstress in anything over about a 1500 fpm descent. Some models just fudge it --- which is then available for us to fly it that way.

In the Evita we also didn't have a chief pilot looking over our shoulder, ready to chastise us - or fire us- for overly aggressive turns, descents or 'hot' climbs that are verboten in something like an airline operation. We all know that to go to that level would deter some of the entrants who've never learned or practiced flying to those parameters - and drive the organizers nuts.

As we do more testing against real-world specs for our various events some of these 'freaks' become known but it's difficult to rule some of them out as there is no alternative model available. That's why I really like Jens' NorthStar... trying to fly it 'beyond the book' just didn't work and from my observations so far, the Connie and Starliner are in the same range of "very plausible" as is the B-377. Of course, the historical data is more available and honest for airliners than for the combat a/c as many of those were known for their propaganda numbers

Both the Evita and last year's Nobel events leaned toward 'realism' and I applaud the gang for their efforts and testing.

[teson1]

Rob, you're a fountain of information and interesting links. Thanks!

[Dangerousdave26]

Rob, you're a fountain of information and interesting links. Thanks!

That comes from 30 years as ATC in Canada.

[MaddogK]

Over Lean mixture will push the CHT up up up, and you will cook the engine. An accepted practice is to lean out the mixture untill you show EGT(if you have one) rise, then nudge it back towards rich. As altitude increases, air density drops, so the mixture needs to be leaned out.Over rich mixtures give lower temps but foul the sparking plugs. One can monkey with the mixture some from the book settings, but the mixture/MAP/RPM/Fuel flow graph has been arrived at by many,many years of trial and error and hard won experience. I have read several accounts of P-51 drivers getting home with cooling systems shot out by running full rich,and stroking the Kholer pump(manual primer) every 4-5 seconds to over rich the engine, keeping the temps just under the red line.It would run like crap, as the plugs fowled, so you quit pumping for a few moments to let the temps climb and burn the lead off the plugs. Don Gentle wrote that, after 2 hours or so of contiuous pumping nursing his Mustang back with a shot up rad, that he had worn the thumb out of his glove, and then wore the hide off his thumb down to the bone, the cockpit looking as if a hog was slaughtered in it, but that was preferable to being a POW.

LOTS of info there, but generally your right- leaner mixtures run hotter ! An over-boosted under fuelled engine should've shown decreasing compression pressures until catastrophic failure (burnt rings, burnt valves, holes in cylinder, etc) no matter how cool you keep the cylinder jackets, but generally failure takes many hours of abuse.

[srgalahad]

Actually from more than that Dave.. my first NorthStar ride happened when I was 6 or 7. Dad worked for TCA and we lived 1/4 mile from Dorval so I was kind of immersed in it. Another member here at the Outhouse taught me to fly at 17 and I've pumped gas, groomed planes, towed them, washed them since I was 13 or 14.
One of these days when I find some time I'll go back and scan the slides I've collected of aircraft since 1960.

Yeah, I have one of those Dyson minds.. spins round and round and picks up a lot...

Rob

[teson1]

Hey guys,
stop intimidating new people. :d

[srgalahad]

Hey guys,
stop intimidating new people. :d

LOL

We were all "new" once upon a time .. in a galaxy far, far away...

Just that some of us started before the dawn of time

Besides, that's the fun of it - picking our brains for the bits that have been stored... if we can find them under all the other junk

[jt_dub]

I had a great time participating in the Evita Challenge. Initially I was a bit disappointed to have finished so far back in the pack but I have gotten over that.

What really gave me satisfaction was taking max loads and the right amount of fuel to avoid landing penalties. The Stratocruisers high fuel consumption outweighed the good speed and load carrying capability of the aircraft.

The B377 is very thirsty and particularly on climb to cruise where I needed to run auto rich to keep the engine temperatures down in the safe range. Once in cruise fuel consumption moderated significantly and as I was to run a much leaner mixture. The longer legs were better for me.

The legs in the tropics were tricky as I had to throttle back almost immediately after take off to avoid overheating. Lots of time spent opening cowl flaps and cooler flaps to keep the flight engineer happy. It took longer to get to cruise altitude too. Descents were less of a problem but required continuing attention to carb heat and flap settings. No combat descents in the 377. Too easy to overspeed and if you throw out flaps above 150knts they will jam. The Accusim add-on does promote “responsible” handling of your power plants. Push’m to hard and you will get a failure. It was very satisfying to complete the challenge on the set of engines I started with. Two were rated as in good condition and two were rated in fair condition at race end.

It was a lot of fun and I learned a lot.

Jeff W

[Willy]

I had a great time with the Evita and flying the JBK Stratoliner. I knew going into the event that I was behind the curve for speed and payload. I was just hoping that the 307's fuel economy would get me through. And I ended up finishing better than I thought I would.

[PRB]

We tried to write the rules in such a way that fire walling would be discouraged because it would lead to a “non-optimum profile”, in terms of fuel consumption, and this would cause people to fly by the numbers to save gas. This didn’t work out exactly like we had planned. We knew we couldn’t simply outlaw going fast, and it wasn’t explicitly stated in the rules that we wanted racers fly “by the numbers.” We wanted to make winning the race dependent on other factors that would naturally lead people to fly “correctly” to take advantage of those other factors, such as fuel efficiency and payload bonuses, as well as penalties for landing too heavy. We didn’t 100% succeed at this, but it did make for a fun and interesting event. Short of flying only planes equipped with A2A style “accu-sim” technology, the goal we set out to achieve with this race seems, at this point, almost out of reach. One simple way, I suppose, might be to provide each aircraft type with a “target” speed, and penalize the degree to which the target was missed, either under or over. The same way a handicap system works. I personally don’t like this approach because it’s too “artificial” and boring. We wanted flying by the numbers to be a logical consequence of the rules (if you wanted to win), and not simply the rule, if that makes any sense. Like I said, we didn’t quite succeed at that, but we’ll keep thinking about it!

[teson1]

Paul,
I think it would be enough to fix the rules clearly next time.
Like, clearly state that take off, cruise and descent/approach are mandatorily to be flown according to the POH/handling notes supplied with the plane, and that no flying ourside of the "recommendations" (and "Limitations") is allowed.

Actually I like Charlie3/7's statemen that "the mixture/MAP/RPM/Fuel flow graph has been arrived at by many,many years of trial and error and
hard won experience." to make such rules comprehensive to everybody, even me.

If this is stated in simple terms, bold letters, and not exceeding 10 lines, at the beginning of the rules, then even I may actually understand it. :d

I think we'd all respect such unenforcable rules without need for tracking and control (except maybe for the RTWR, which, I feel, can get quite
competitive).
There's of course the danger that somebody with little experience (that was clearly the case for me this time), or with a plane that does not have
good documentation, or a plain unrealistic flight model, may fly outside of the realistic envelope. So what.
I think we'd have fun nevertheless.

In any way, you at SO did a terrific job designing a race format that promotes racing in a realistic environment, which I would love to see in further events.
And I'll do my best to conform next time - and finish well nevertheless. :d

Cheers,

Gunter

[RFields]

Would I (and the plane) have survived the trip?

+ What would have happened to the engines?
- Would the engines have worked at all with very lean mixture?
- Would the plane have arrived at all at a leg's destination or would the engines likely have failed in flight?
- Would the engines (and other parts) have to be changed after each leg?

+ Would the real plane have behaved the same way regarding fuel consumption/speed, or is it a quirk in FS that consumption decreases so much with very lean mixture?

I was never a Connie flight engineer, but I knew/ know several. I've also been on several Connies when an engine had to be shut down, and one memorable occasion in the cockpit landing at Danang with both engines out on one wing.

Time frame is important. Any Connie flying today will be flown very carefully and the engines treated like newborn babies.

In 1972-74 when I flew on them, parts and engines were beginning to be hard to find. While every plane which was sent to the boneyard was a potential warehouse, the long range quality of the parts was always a question. We had easier access to P-3 engines with only two aircraft, than Connie engines with seven aircraft.

In 1949, the Connie was a new top of the line model, and pushing the numbers to set fast trip times was common.

In a contest such as the Evita was framed, all the airlines would have pushed their crews to fly as close to, or slightly over, the high end numbers as possible.

The Wright 3350's had two banks of nine cylinders for each engine. As many hours as you flew, it would be unusual to not change at least one cylinder. Those cylinders could be removed from the outside of the engine and replaced within a couple hours. We always carried spare cylinders in our onboard parts kit.

I remember we did checks on the cylinders, pistons and such after 20-25 hours of flight. The FE and the mech would be out soon after landing putting their hands on cylinders trying to see if one was too hot or too cold.

We seldom burned a piston. I don't remember breaking a connecting rod or crankshaft. I do remember some broken valve rods, but the most common problem when an engine got too hot was an indication of metallic chips in the oil, or a bad oil pressure indication.

I had an old FE tell me a year or two ago how much he would have loved the current sensor technology to tell him the cylinder head temp for each cylinder which is available on some relatively cheap GA aircraft today. Though he wondered how to keep track of all 72 cylinders.

We really don't fly realistic often. We don't have the two main penalties - the cost and the possibility of death. It is hard not to push ahead a bit.

I flew the Lancastrian a bit hot, but I kept everything in the green. Not in the middle of the green, on the upper edges, but in the green.

[teson1]

Reggie, thanks for the insight. We do have some people with some amazing experience here.

I suspect that the main point where I veered from realism was really the ultralean mixture I flew with.

I had an excess of about 50% air in the mixture I believe (vs a stochiometric mixture fuel/air), and at the same time pretty high power.
- Do you think that with such ultralean mixture the engine would have worked at all?
- Would there have been detonation (the higher the MAP/pressure in the cylinder, the higher the temperature increase after the compression cycle, no?) or other effects destroying the engine? (Btw, CHT was in the green during flight).
- The engine should at least have run very rough, no?

What do you (and others) think about that?

In fact I suspect that the FS model of engines is not accurate in so far as the effect of mixture is concerned.
As far as I understand, from what I have read in the meantime, in reality the Brake specific fuel consumption (BSFC=FF/BHP, fuel flow to achieve a given BHP) is lowest at maximum EGT-50°F or so, and should increase again if the mixture is leaned further. However, it seems that with the model I have flown, it decreased further with leaner mixtures.
Should be pretty easy to test within the sim, but I can't fly for the next two weeks or so to test that.

PS: This is all new to me, so I may have completely misunderstood the functioning of the engines. May be BS.
Btw, I liked the following presentation on how an engine works:
http://www.njsflight.com/resources/general.html - High performance engine operation

PPS: - I was in the green everywhere as well - temps, pressures, ect. (though I exceeded the rec to stay below 43 psi, MAP was still in the green as well).

[teson1]

PPPS: I had looked at the flight parameters with AFSD: TO power was Shaft horsepower (BHP?)=3280 HP (per engine, max_rated_hp=3250 HP), cruise was about 2140 HP, i.e. about 67%.
That's not straining the engines too much, isn't it?

[RFields]

The issue is not how FS models engines, or specific components of engines.

The issue is how modelers design their engines and their failure to use the capabilities to model damage.

While there are some things you can do with aircraft to cause catastrophic damage, only a very few designers work with cumulative damage.

One of the things I like about the FSD aircraft was that the impact of running an engine improperly over a period of time would cause the aircraft to have poor performance.

If modelers would write their flight dynamics to keep track of engine hours, to keep track of abusive flying and institute degraded engine performance - that would make a lot of people fly much more realistically.

But they don't do that because the FS community does not want that type of aircraft.

One of the reasons I like Copley's P-38 is that you can hear the engines running poorly when the mixture is off.

I do remember one FE who told me that listening to the Connie engines was important to get the best performance. I don't ever remember seeing all four mixture controls at the same setting in cruise. All the engines on our aircraft had different hours on them, and each engine needed to be set individually for best performance.

Low mixture, high MP, etc - among the problems which can occur are burning spark plugs and fouling spark plugs. Given the region and the stops, the possibility of off octane fuel was high. I don't think FS can simulate an 18 cylinder engine losing a cylinder because of fouled plugs, something I have experienced in real life.

Flying "by the numbers" is an approximate. Without the aircraft POH, you really cannot set the correct numbers for your flight. The numbers for the Rio to Sao Paulo leg would be different than the numbers for the Atlantic crossing leg.

And with recips, each plane, each engine varies those numbers a little.

Flying by the numbers is a range, not a this number MP and RPM only idea.

The crew has to make the decision about the tradeoffs. Pushing the plane to ultra lean mixture could easily have not had a negative impact upon the 30 hour or so flight. But it would have had an impact on the life of those four engines.

The 3350 was never cheap - as I said above we can never come close to the cost factor in flying, which is so very important in the real world.