New P3 Orion

Allison / Rolls Royce T-56

Hello Aleatorylamp,

First of all, the point I was trying to make is that it doesn't matter whether a 4600 HP piston engine ever existed.
You are playing with a CFS simulation of a piston engine.
If you want 41 cylinders in your engine, then there is really nothing to stop you.
I am pretty sure the simulator isn't smart enough to limit you in that way.
If you want 18,000 HP, then just keep increasing parameters until you get what you want.
We are not working with real physics here.

Regarding the P-3 Orion's performance, check the NASA guide (Page 11) for maximum speeds.
Regarding the Allison T-56's power curve, a quick Internet search (Global Security Site) shows this engine as making 4000 HP through the propeller and about 800 pounds thrust through Jet Exhaust.

Between those two sources, you should have a pretty good idea of how the Shaft Horsepower varies with altitude. I am guessing the Exhaust Thrust does not change very much but I could be wrong there.

Regardless of what the power output is, the performance goal is pretty well documented at least for the NASA P-3 Orion.

- Ivan.
 
Hello Ivan,
OK, I get it now. Thanks vey much for the clarifications!
I was already looking into the docs you mention, and I´ll see what I can do.
As regards the unwanted bulge or peak in the performance curve of piston engines, I got the impression that it is similar to a 2-speed supercharger that sets in at a given point to add extra boost - which of course distorts a single-speed one.

Update: I think perhaps I haven´t been able to put across the issues I´m finiding. It is not so much WHAT I want to achieve, because that´s clear - it´s a turboprop´s performance curve achieved by using a CFS supercharged piston engine - but HOW to achieve it. That is to say, HOW to use CFS supercharger parameters to the optimum, in order to cater for the turboprop´s higher ability to counteract loss in altitude.

Of course, not so well as a jet engine´s ability in FS98, because we know we are still using a prop.

I just saw an english turbo compound, the Napier Nomad, a 12 cyl engine with a 89 psi boost turbine... 181 Hg... Quite inpressive. That indicates that cylinder capacity could be smaller, around 100 cu. in, but 3 time higher Supercharger Max MP. More experimentation! I´ll see what happens to the CFS .air file!

Anyway, thanks again,
Cheers,
Aleatorylamp
 
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Hello again, Ivan,

It is again getting very interesting indeed. The information I needed was just under my nose - not so far away to look for!
You are absolutely right about the exactness of the NASA P-3 Orion document!
I was again unnecessarily complicating my life ... (typical!)

With the experimenter´s Handbook Page you pointed out, (thanks a lot again), the goal to go for is a great deal clearer than just the max. speed of 411 mph for 15000 ft that I was relying on. The speeds for different altitudes at different aircraft weights are a solid reference to go by, maximum continuous being the key.

Funnily enough, for an engine similar to a Napier Nomad II type with a boost of 181 Hg max. MP, hypothetical 16 cylinders with 99 cu.in per cyl and 8.25:1 compression ratio, I have to set Boost Gain at 12.45 (good Heavens!), to get the 181 Hg at the expected/wanted altitudes. RPM was also slower, at 2025 RPM, than the Wasp Major´s 2800. Totally crazy but amazing, this English 2-stroke Diesel Turbo-Compound...

The performance curve behaves very nicely under max. power and is very similar to the numbers on the Experimenter´s Handbook, although speed at S.L. is still a bit high.
The "unwanted" bulge I was mentioning is perhaps not so unwanted, because it can be seen from the Handbook speed table, that performance is higher at 20000 ft than at 15000 ft, so the peak is probably not so unwanted, but quite correct - at least for this "Napier Nomad" type test.

I still have to conduct the maximum continuous test, just for the sake of correction. This seems to be a 97% throttle position. It occurred to me that one could limit full throttle by implementing 4 or 5 Hg of WEP for Take-off, and leaving 97% i.e. 176 or 177 Hg for Normal Maximum.

Next, I can go over the numbers of the P&W Wasp Major type engine tests, to see if those were not so incorrect either.

The objective of my experiment is to see which combination between Supercharger Settings, Engine Capacity, Compression Ratio and Cylinder numbers will produce the best turboprop-similar power curve.

Update: Oh, what fun! NASA Experimenter´s Handbook speeds are in Knots - here I was thinking I was 50 mph fast, and I´m really 1 or 2 Kt slow. One gets caught out yet again!!

Cheers,
Aleatorylamp
 
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Hello Aleatorylamp,

I am glad you are getting useful results though I have to admit I would have approached the problem from a different direction.

At some point, I will need to get a P&W R-4360; It will be hauling around a F2G Corsair and I actually have been looking through my data sheet on the Corsair because I intend to rebuild the visual model around the correct CoG.

Simulating a Two-Stroke Diesel with the CFS piston engine sounds pretty interesting. I can't say I have ever tried it though I HAVE tried to build a Rotax engine and had a fair amount of success.

Anna Honey and the kids are out of town for a couple days. The class in Boston / Cambridge will be over soon and Anna and my Son are heading up there to pick up my Daughter and bring her home. I wanted to go but could not because of other responsibilities. I just got home about an hour ago and may even fire up the development computer tonight.

- Ivan.
 
Hello Ivan,

There were definitely some intriguing and striking engines! Another really bizarre one was the 2-stroke Jumo Diesel with two crankshafts and two opposed pistons per cylinder, with the advantage of its low vibrational level. It was quite effective, but also had its problems.

Your Rotax would be really good for an enhanced default AF99 Ultralight for CFS! ... with BB guns on the wings!

I think the reason for my different approach is that I need a more tangible example to start off with, whereas you know more about how modifications to parameters work and wouldn´t need an example engine to as a starting point.

With my mph and Kt confusion, now I´m rather short on speed as altitude increases. I think I´ll go back to the more efficient Mitchell-C propeller that I have on the Baltimore, instead of the P47 one, as it was more efficient! I had taken the P47 one because with the mph and Kt confusion, I thought it was going too fast!! Confusions never loose their funny side...

My wife kids are all on holiday after their successful yacademi years, and go to the beach in the sweltering heat - I still have the German for waiters course at midday until the first week of September, which however keeps me on my toes and away from the beach. It is just as well, because the sun plays havoc on my skin.

Enjoy the development computer!
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I did power up the development computer last night but only did some experimenting with the Macchi C.205.
The Orion was in the plans but never got that far before I got too tired to do anything useful.
I just got home a few minutes ago, so we shall see if I get to it tonight.

- Ivan.
 
Provisional results - maybe interesting?

Hello Ivan,
I hope your development computer is still bravely battling on!

I got some provisional results from the turboprop experiments with a CFS supercharged airfile.
All in all, for the moment, there seems to be a problem getting turboprop-like power at altitude.

Basically I used three engine models. One with a high number of large cylinders and high but still relatively conventional supercharging and compression ratio (Wasp Major), one with with fewer and smaller cylinders, with very high compression ratio and even higher supercharging (Napier Nomad), and a third one which was in-between (fictitious).

First of all, trials with the first two engine models, with power settings for 4600 eshp at 15000 ft as per most specifications proved very unsatisfactory because there were only about 4000 Hp left for S.L. take-off, and the fully tanked up plane without bombs was sluggish and cumbersome, despite the fact that speeds were higher upto 8000 ft. Further up, 20000-28000 ft), performance was also very poor.

The NASA experimenter´s Handbook states 4600 eshp for Take-off, so I used this as a main reference from then on,
trying to fit the performance as per the performance chart on Page 10 in the Handbook.

This improved performance and handling at lower altitudes, but higher up, things were still unsatisfactory, even though now we were getting 5000 to 5300 eshp readings.

The high-boost Napier-Nomad-like model tials had greater performance losses higher up, between -35 and -44 mph, compared to the lower losses of -24 to -9 mph losses the Wasp-Major-like engine, despite having higher speed values at low altitudes.

Reducing Drag, with the objective of raising speeds at altitudes at the cost of also raising low-altitude performance even more, only did the latter, and almost made no difference higher up.

Low-altitude speeds were not so high above specification with the Napier-Nomad +8 to +17 mph, whereas the Wasp Major ones were +19 and +23. So the low-boost Wasp Major lost less power higher up but was too powerful lower down.

The combination Napier-Wasp behaved a little better higher up than the Wasp Major, and about the same lower down.

In conclusion, for the time being, it looks like the piston engine power curve has problems in providing high-altitude power similar to a turboprop, even if the whole curve is up-shifted at the cost of excessive power lower down.

I tried setting Minimum Manifold Pressure to 0 (the old Low Altitude Boost Related which is always at 1 but had no effect other than increasing speeds by 1.5 mph at low altitudes and 0.3 mph higher up.

If I come up with more ideas, I´ll try them out - if it gets a little cooler here at the weekend and the brain gets some fresh air!

Update: Of course, not to be discarded is the possibility that the airframe in the .air file is creating the problems and is the culprit for the difficulty in getting enough speed at altitude despite increased power... Things get a little complicated sometimes.

Cheers,
Aleatorylamp
 
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Hello again,
Just to wind up the study:
I thought of making and testing a different, fictitious, very large engine with lots of huge cylinders, lowish compression and rather normal supercharging (max. 60 Hg), also giving max. 4600 eshp at S.L., and results were very, very similar:

As before, it needed to be given considerably higher speed than specified for S.L. (+44 mph), and performed considerably slower at the 20000 ft performance peak (-24 mph), and a little lower (-6 mph) at ceiling. Looks like the resulting 5300 eshp or so at 20000 ft are not enough.

I checked the air frame i.e. wing parameters por possible excessive air resistance anomalies, but there was nothing strange. Oswald factor was at the usual 6750, and changing the angle of twist from -1 to 0 made no difference, so I left it at -1.

Anyway, so then I´ve arrived at the end of my tether!

Now I´ll go back to the Baltimore aircraft and get the engine-nacelle components going to substitute the present structures, and see if I can improve the solid-looking stepped nose so that it doesn´t look so strange.

Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Earlier today I revisited the P-3 Orion also.
The first thing I noticed was that the shapes were somehow just a little different until I finally realised that it was your project I was actually looking at.
When I got back to my own project, I was wishing that I had not tried to simplify the engine nacelles. The earlier shape was better and now that I have given up on trying to finish the project within AF99, resource count really does not matter as much.

Now that this project is getting more attention, perhaps I should create a real directory for it instead of just throwing it into the Workshop general directory where it constantly gets overwritten. This would be my first major SCASM project so there needs to be a bit more than the usual planning.
I also need to do a lot more research than I have done to this point to put the rest of the project together.
By the way, you already released your version with a Jet Engine and were obviously satisfied with the results, so why are you revisiting the same project with a piston engine? I am going in that direction because I don't know anything about CFS Jet Engines.
I really should complete a few other more deserving (WW2) projects before this one though.

Anna Honey and the kids are still away. Today they visited my Alma Mater. I directed them to a place that I remember has a really great view.
Afterwards, my daughter asked me if I had taken Anna Honey there before because it seems familiar to her.
I told her that I had. What I did not tell my daughter was that it was almost 20 years ago though.

- Ivan.
 
Hello Ivan,
Nice post! How old is your daughter? Her age doesn´t really tie in with a 20-year-ago visit to the place with the great view. One wonders about the real nature of some memories.

For the great shape of your P-3 Orion engine nacelles, parts count on your model is very high, and to finish it I´m sure it is another valid candidate for SCASMing, which will definitely yield some good worth-while results! Nevertheless, don´t feel pushed to do this sooner than you like though, just because of my current interest in its CFS flight dynamics possibilities, especially if the project will need such careful prior planning and additional research.

My interest in the "CFS-Turboprop" experiments, was triggered by your perhaps rhetorical question on how to go about a CFS .air file for the Orion, and the reason was only curiosity, just to see if it was possible to produce a flight model with a power curve more similar to that of a turboprop using a CFS .air file instead of the FS98 one.

In this case, upto now, I have the feeling it is much more like a piston power curve, and would require some good modifications to adapt it to give better power at high altitudes. I tried out some but wasn´t really satisfied yet. Perhaps supercharger power would have to be increased further, but it there does not seem to be an obvious way to do that, and for the moment, the Horsepower needed goes way up to beyond 7000...

The aircraft, with the jet engine .air file, behaves correctly as regards the generally specified speeds (not the ones in the NASA Handbook), the performance envelope being between 400 and 411 kt with max. throttle, although the power curve is rather more smoothly linear and jet-engine like than would be desired. I´d mistakenly mentioned the speeds in mph instead of kt in my post!

Anyway, your next project should be whatever really tickles your fancy, as the English say!

Update:
I am translating a jet-engine parameter tutorial from German into English, written by one André Léderer, which contains some interesting guidelines as regards the use and effect of the different jet-engine parameters. I will attach it to my next post, and it will probably be quite useful.

Cheers,
Aleatorylamp
 
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Hello Aleatorylamp,

My revisit to the Orion last night was mostly related to looking at rebuilding the Fuselage to allow for good texturing.
I don't know if I can use more than 16 textures, but that is the way it is looking right now to do it well.
The Fuselage is the area that I believe needs the most consistent texturing and so far I am finding that 45 feet to 256 Pixels is about the best I can do unless I start REALLY cutting it into a few more sections. The problem there is that I will then need about 20 texture files and I wonder if CFS will have problems displaying.

Off topic, but I believe that the P-40M Kittyhawk Mk.III needs so little work (Just a revised AIR file presumably based on the P-40N) that it would be a shame not to fix it first. I also did some more checking on texturing for the Macchi C.205 which means that a revised version of the C.202 may also be coming out shortly.

Regarding ages.... I graduated from college 30 years ago. You can see my age.
My Daughter is 16. Anna Honey and I were married almost 19 years ago. She and I dated for around 4 years.
So.... On the last visit to this location, I am sure that it was just Anna Honey and myself without kids but I do not recall if we were already married or not which means it could have actually been OVER 20 years ago. I am guessing we were already married though which puts it under 20 years ago.
If we already had a child, we would have had a baby carriage on that trip and I don't remember travelling that heavy.
So everything does fit together logically even if my memory may be faulty at times........
That was certainly a simpler time.

- Ivan.
 
Jet-engine parameters for turboprop .air files

Hello Ivan,

My wife and I dated about 4 years as well before we had our daughters. Time flies! We started going out in 1990!
I actually meant your daughter´s memory, i.e. her feeling of familiarity with place with the great view, and I was giving it a more metaphysical interpretation. In that sense, memories are perhaps more related to dreams, and there are some rather intriguing interpretations as to how these are possible... Of course a more pragmatic approach would be that your daughter had been to a similar place in her life.

Well, you seem to have quite a number of interesting things on your to-do list. At least it´s better than not having a list!!
I believe anything built with AF99 has a limit of 16 texture bitmaps, all 256x256. In order to go above that, over 16 or 512x1024 bitmaps with more colours, (similar to FS2000 or 2k2), maybe something like FSDS1 or most probably SCASM is needed, but I don´t know the limits of CFS1 itself.

Anyway, here´s the jet-engine parameter document I mentioned. It´s a kind of tutorial that André Lederer wrote for me when I was fixing up the flight dynamics on some DC3 Turboprop conversions with PT6-A turboprops. These were the Turbo Dakota and the incredible Polair Tri-Turbo Three.

I put in some additional comments and a comparison between ADE98 and AirEd parameter names, also showing how some of the numbers in the parameters change depending on the editor. It is quite interesting to see that there are a number of jet-engine features that we can actually have influence on! Hopefully it will be of assistance to you should you want to play around with the jet engine .airfile for the Orion´s turboprops.

Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Thanks for the Jet Engine document. I will read it when I get the chance.
I don't believe CFS can handle anything more than 256 x 256 pixel texture files. I was wondering if the 16 texture file limitation was purely AF99 or because of CFS limitations. That part doesn't matter so much yet. There is much to do on the model before that.

I can start doing a little research and poking around for data on the Orion AIR file even with just this laptop computer.
I certainly can't do any building or testing with it.

A few days ago, I did some looking around at documentation for the Corsair and believe I have a reasonable estimate for the CoG of that aeroplane.
I wonder how close the F2G will be in that respect....

I see the confusion. It was Anna Honey's memory she was describing to me over the phone.
About to head out to Mom's house again. She is not doing well.

- Ivan.
 
Hello Ivan,
I do hope your Mom slowly gets better.
One extra thing on the jet .air file if and when you get around to looking into it:
Parameter 601, which is the Jet Power vs Mach curve. Perhaps making it fall a little after the 5th column or so... if each of the 16 columns represents 62 Kt, as in the Wing CL vs Mach graph - then one may get a more turbo-prop like power curve?
Cheers,
Aleatorylamp
 
Hello Aleatorylamp

Perhaps it will be more useful if and when I get to working on a Messerschmitt 262. That is in the plans also at some point.
I don't think the steps are really 62 Kts. Usually it is 0.2 or 0.4 Mach but of course that will vary with altitude.
At least that is how it works with other Mach graphs in the AIR file.

My approach to this AIR file will be a bit different than the usual one.
The basics need to be done first with a proper loadouts in weapons, fuel and airframe.
I have done no research there, so I will need to create a data sheet at some point.

For Performance, the first step is to translate the NASA table to True Air Speed in MPH. I prefer not to work in Kts.
Next is to find the amount of thrust required at each altitude to achieve that speed.
Next rework Propeller Table 512 to be able to absorb the amount of power these engines generate.
After that, Propeller Table 511 gets corrected to make up for the Exhaust Thrust.

That is my idea at this point, but keep in mind that I haven't really started doing anything yet so the plans will certainly get changed as required.
At the moment, my AIR file is that of a 4 engine B-25 Mitchell which is all I needed to build the visual model.

We shall see.
- Ivan.
 
Hello Ivan,

OK, thanks. I´ll test the columns to see what speeds are proper.
Your 4-engined Mitchell .air file sounds most intriguing, even if only just to get by for the visual model!

Yes I fully understand what you say as regards to your plans, both as regards the Messerschmitt 262, as well as the sequence of steps to proceed with for the Orion´s turboprop CFS .air file conversion. No hurry, no problem!

I translated one of the NASA Experimenter´s Handbook speed columns into mph - corresponding to 110000 lbs weight, as I was getting about 125000 lbs for a fully tanked, crewed aircraft with no bomb/missile payload.
From S.L. to 30000 ft the max. continuous speed values converted from Kt to Mph are:
345, 385, 397, 408, 421, 433, 446, 454, 450, 447, 439, 425, and 404 mph.
I wasn´t using the 30000 ft. line because the plane didn´t really hold the altitude with 125000 lbs weight, which is not really surprising.

I was also thinking along the lines that the only way to get more speed at altitude was to tamper with the propeller graphs, but didn´t dare! I remember your comment very early on when we were tuning the Zeppelin Staaken engines, that moving the propeller table columns to the left by two positions would increase efficiency and thrust. Maybe I will dare now... It could be interesting... just for kicks!

As an approximation, I expect the calculated thrust values would be based on the estimate a few days ago, that added the propeller thrust and exhaust thrust, the latter being more or less constant with altitude, as opposed to the former.

OK, then, all in good fun.
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I was looking over the NASA speed table for the Orion yesterday.
I am actually more interested in the 90,000 pound or 95,000 pound columns because they give maximum level performance.
The first thing worth noting is that maximum is only 404 knots while the Orion should be good or 411 knots.
The question here is now to make the correction for a target speed. I DO want maximum speed as per specifications.

I do believe that the propeller tables are the key to this AIR file.
Until I create the rest of the AIR and DP files, I cannot get a good feel for what the propeller tables should be.
As I commented earlier, I really don't have an interest in the Orion, but it does offer an interesting learning opportunity as far as AIR files go.
Hopefully we will get there eventually.

Today I have a young guest staying at my house. My nephew wanted to get away from all the tension over at my mom's house, so he came over last night. Guess I should go make some breakfast.

- Ivan.
 
Hello Ivan,

Baked beans on toast with a fried egg and sausages, or also bacon and eggs make a nice English breakfast if it´s cold... In hot weather I suppose corn flakes with cold milk, sugar, cinammon and sliced bananas will do! Anyway, it´s nice to have youngsters around the house sometimes.

As regards the Orion´s performance tables on the NASA handbook: 404 Kt (464.9 mph) would be with maximum-continuous on the turbines, and that will probably mean 97% N1 power, if the Orion´s turbines are similar to the usual, normal turbines...

Then, the 411 Kt (472.9 mph) maximum take-off power would be under maximum throttle setting, perhaps 104 or 105% N1.
I have to investigate a little which % of N1 power is correct for the 5-minute maximum on these turbines.
In general, it is apparently often over 100%, but will depend on the manufacturer.

So, the good news is, that your conviction about the propeller tables, once finely tuned with proper research and development, means that a CFS .air file can provide a satisfactory turboprop engine. That will ge great!

A correct .air file for the rest of the plane, as a starting point for a more meticulous kind of investigation, is of course also a must. In my case I´m afraid I can only arrive at approximations, due to my more limited knowledge on the subject.

Then, I think I made a mistake in my memory with shifting the propeller table columns to increase thrust and eficiency. This is just for an approximate try to improve this aspect. I remember starting on the right, so columns are to be shifted 2 positions to the right, not to the left! My memory is getting worse... but my age is getting better...

Even if the Orion in itself is not really interesting for you, I´m glad that it has aspects that do attract your interest. In my case, I find the different kinds of aircraft engines and their differing performances fascinating, and I will thankfully be able to follow your study on the subject with interest whenever you decide to start with it.

Update:
As regards the "approximate" adjustments to the propeller tables that I was trying, or going to try: I used AAM because of its visual display, but to be honest, it is all very much over my head and I don´t really understand what or how it is to be done, so I´m afraid I´ll desist for the moment. Not to worry, however, there are other tasks awaiting attention!

Cheers,
Aleatorylamp
 
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