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Thread: Junkers Ju-52/3m

  1. #126
    Hello Aleatorylamp,

    Instead of getting your own aeroplane shot down in which case you get to see just ONE case of aircraft destruction (and it isn't even guaranteed that a part will come off instead of the whole aeroplane just 'sploding), why not go against 12 novices and see how THEY get blowed up?

    - Ivan.

  2. #127
    Hello Ivan,
    I got as far as watching pieces getting shot off my Spitfire in successive
    attacks until it exploded.

    Trying it the other way around, Iīm not very good at being a fighter pilot,
    but I did get some hits in, and saw sparks of where I was hitting, and pieces
    flying off the enemies.


    Then, I had a look inside COMBATFS.CFG searching for a clue for any
    way to control or use this feature but I didnīt get very far.

    As far as possible bitmaps to be used are concerned, it seems like the pieces
    flying off the planes are just real-time generated untextured polygons and lines.
    What remains textured, is the aircraft itself without a wing, falling out of the sky.

    Well, weīll see...
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  3. #128
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    just a thought or two,
    i recall seeing wings and such flying off bombers.
    try this, in quick combat, select a docile adversary.
    the c47 is perfect...slow, unarmed and flies straight.
    aim for the engine or wing root.
    sometimes the magic works.
    sometimes it doesn't.

  4. #129
    Hello Gentlemen,

    Smilo is right. I was trying to describe having large pieces such as a wing fall off the aeroplane, not the silly little squares of junk.
    I know it can be done. I just don't have the drive to do the research and experiments.

    - Ivan.

  5. #130
    Hello Smilo, hello Ivan,
    It sounds like a great idea, to take advantage of this feature and turn
    a large chunk of shot-off wing into a parachutist, which would spawn
    off your plane without it being damaged, and then merrily float to the
    ground!

    However, and needless to say, Iīm afraid I havenīt the slightest clue
    as to how to go about such a thing!

    So, for the moment at least, Iīd be in favour of keeping it simple and
    practical, and use the CFS1/Dp-file bombload feature.

    This way at least the simmer can decide the how many paratroopers he
    wants to load, and then drop them somewhere.

    Alternatively, the plane could also be defined as a simple troop transport,
    for upto 18 or 19 troops to be landed somewhere - not dropped, so at least
    they wonīt explode!

    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  6. #131

    Tweaking the different BMW132 engines for Auntie Ju

    Hello Ivan, hello Smilo,
    I am still not quite satisfied with the engines in the .air files of the different Ju52 models. Although maximum power and performance is quite OK, continuous power and performance seems high, so Iīm going to improve this, but first I checked for more exact information on the different engines, and stumbled upon some problems which donīt exactly help.

    Some time ago, we put in the engine parameters for the FW200A Condor, aiming for the specified 720 Hp at 2050 RPM at S.L. We had found reliable data as to the 6:1 compression ratio, and the 1.2 ATA max. MP from the FW200A operating manuals. The engine type was referred to as a BMW132A or BMW132G-1. This engine is the same type as on the early Ju52/3m g3e and g4e versions, that had 660 Hp BMW132A and 725 Hp BMW132A-3 respectively, both rated at 2050 RPM at S.L.

    Engine power on later military versions of both aircraft (FW200A and Ju52/3m) increased, as the BMW132 series was improved, Hp reaching 850 and over, and RPM going up to 2400.

    I have always been intrigued as to how exactly the power increase was achieved. Apart from more better materials, more efficient cams, lubrication and refrigeration, the obvious candidates are compression ratio, and manifold pressure. However, there is surprisingly little detailed information on these facts.

    So where did the 65 Hp difference between the 660 Hp and 725 Hp engines come from?
    Some sources state different compression ratio, giving 6:1 and 6.4:1 respectively, although most quote the same 6:1 for both. Then, one source even mentions a MP value of 1.25 ATA instead of 1.2 for the 725 Hp engine.

    Updated paragraph: Incidentally, some sources state the A-3 as giving 715 Hp, which is curious, because ifan .air file regulated to 660 Hp, with 6:1 compression and 1.2 ATA max. MP, were to be modified by increasing compression to 6.4:1 and MP to 1.25 ATA, we get 717 Hp.
    Well, so maybe the militarized Ju52/3m 725 Hp engine needed more MP and compression ratio to get the 725 Hp, whereas the Condorīs civil engine, being newer, gave almost the same power with lower compression and MP?

    Nevertheless, it is not serious, because the .air file can be made to give correct performance in both cases. I could just leave it as it is, given the fact is that the FW200Aīs 720 Hp engines had 6:1 compression and 1.2 ATA.

    When the aircraft was later further improved to the g5e version, the 830 Hp BMW132T-2 engine was used. Here, I had overlooked the 6.5:1 compression ratio!
    At least I have one realiable piece of information to make the necessary corrections.

    All BMW132 engines with 800 Hp or above had 6.5:1, and power ranged from 800 Hp on the -L version to 850 Hp on the -Z Version. This last one also had direct injection and 3-bladed CV propellers. Apparently the use of CV propellers increased RPM to 2400 on these engines, which only did 2300 RPM with the 2-bladed 2-pitch props. There was even a civil version, the BMW132-Dc, that gave 868 Hp and had a compression ratio of 6.93:1.
    Possibly manifold pressure also increased, but I have found no reference to this.

    Update No. 2:
    As an afterthought, if the difference in power from the 660 Hp to the 725 Hp engine came from increased compression and MP, how would one account for the further increase of 105 Hp for the 830 Hp engines? ...apart from just increasing the Torque graph, of course! ...or shall we just forget the whole issue? Also, itīs quite doubtful whether itīd be noticeable when flying.

    Anyway, Iīm managing to tweak the propeller tables in order to tone down normal performance a bit, and itīs going OK.
    Cheers,
    Aleatorylamp
    Last edited by aleatorylamp; February 8th, 2018 at 05:57.

  7. #132
    Hello Aleatorylamp,

    I know nearly nothing about Tante Ju or her engines at the moment so this is pure speculation.
    Could it be a supercharger change?
    Do you have any particular model numbers of the aeroplane and engine combinations you are particularly interested in?
    I MAY have collected data in passing, but I would need to know what I am looking for.

    If you happen to have graphs of power versus altitude, you could probably make a pretty educated guess as to the changes.

    - Ivan.

  8. #133
    Hello Ivan,
    Thanks for your reply. I was worried that you perhaps wouldnīt have any suggestions,
    as you normally deal with fightersī twin-row radials with twice the power.

    Nevertheless, Iīm glad that apparently thereīs some hope.
    It seems then, that there is a possibility of there having been different blowers.

    The Ju52/3m g4e with the 725 Hp BMW132A-3 engines in question is the one recovered from the Norwegian Lake Hartvigvannet, at present restored and on display in the Norwegian Museum Forsvarets Flysamling Gardemoen: Model Number (Werknummer) 6657 with registration CA+JY.
    Another candidate for this one could be a g4e at Wunstorf Museum, Germany: Werknummer 6693, registration DB+RD, also recovered from the same lake in 1986.

    Basically, there are 2 questions:
    a) whether this model had a 1.2 ATA supercharger like the FW200A Condor had, or if, being a military machine, the supercharger was stronger and gave 1.25 ATA.
    b) Whether the compression ratio was the civilian normal 6:1, or if it was 6.4:1, having been militarized.

    Attached is also the Performance/Altitude diagram for the BMW132 series I have. The visible .jpg picture is the same one as in the .zip file, for resolution reasons. I hope it is understandable.

    Then, I will try and find a model number for the other plane in question, the Ju52/3m g5e with the 830 Hp BMW132T-2 engines that had 6.5:1 compression ratio, just in case it were possible to find out if this one had an even stronger blower, giving perhaps 1.35 ATA.

    Update:
    I found out that Werknummer 6935 was definitely a g5e, and then, probably also 6811 and 6855. Apparently only 231 of these were built, but the engines were the same for the g6e and g7e.

    Perhaps you could have some information on these, that you collected in passing.
    Thank you very much indeed, in advance, for your help!

    Cheers,
    Aleatorylamp
    Attached Thumbnails Attached Thumbnails Motordiagramm.jpg  
    Last edited by aleatorylamp; February 8th, 2018 at 12:36.
    "Why make it simple if you can also make it complicated?"

  9. #134
    Hello Ivan,
    Analysing the performance chart a bit, it seems like a generic one relative to the group of engines in the BMW132A series. BMW mentions low-altitude and high-altitude engine series, so this one would be the 6:1 compression low altitude series.

    Interesting to note is the 1.2 ATA curve, which starts with 690 Hp at S.L.
    It reminds me of one specification for this engine, that states exactly this, whereas a number of others mention 725 Hp at 2050 RPM for take-off, some also adding 780 Hp at 2900 metres.
    This would confirm your comment relative to possible supercharger changes.
    Looking at this chart, one could possibly interpret that the 725 Hp engine did indeed have a bigger supercharger, possibly 1.25 ATA.

    The source that mentioned this, is a member of the Sturmovic forum, talking about a military Ju52 manufacturers power chart, quoting different ATA settings for different powers and altitudes, which would consequently lead me to believe that this information is accurate:

    >Quote

    According to the manufacturers power chart:
    1min - 2050rpm/1.25ata - 725PS@0m
    5min - 2050rpm/1.13ata - 640PS@0m, 660PS@900m
    30min - 1975rpm/1.06ata - 575PS@0m, 600PS@1400m
    max. continuous - 1930rpm/1.02ata - 535PS@0m, 565@1700m
    cruise - 1860rpm/0.96ata - 485PS@0m, 515PS@2200m

    >Unquote

    Note: 725 PS would be 725 metric Hp and 715 Brake Hp.
    I wonder what Hp measurement is used by the Beckwith Gauge Stack...

    I know that there are pilotsī and operation manuals available on the net, but all have to be paid for. The only free one is a BMW official extensively descriptive document on the low and high altitude engine series, that however makes no reference to any performance or ATA values.

    Then, for the more powerful 800-850 + Hp engine series with 6.5:1 compression, the same criteria would apply, but would presumably have a different performance chart.

    Sources quote 790 Hp for take-off for one specific engine model, and the higher 800, 830, 850 and 880 Hp also mentioned for other engines in this series would then also depend on the superchargers that were installed.


    With the improved propeller tables, the simulator itself seems to be a useful tool to test speculations as to the blowers used on the different engine models.

    Anyway, these are my deductions and reliable data so far, and Iīm still searching for the high-altitude series chart.
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  10. #135

    Superchargers versus Manifold Pressure

    Hello Aleatorylamp,

    I believe you are working under a few misconceptions.... Or perhaps I am.
    Here is my view of the way superchargers work:

    Some basic background (which I am sure you know, but others may not).
    Basic Engine Parameters:
    Compression Ratio
    Displacement (In CFS, we don't distinguish between long stroke and short stroke engines.)
    Maximum Boost / Manifold Pressure

    Then we have the Supercharger
    We can have single stage, two stage, or even more stages.
    This generally affects to what altitude the supercharger can maintain sea level boost pressures.
    We can have single speed, two speed, or even more speeds in real life but in CFS, we can only simulate power curves for SINGLE SPEED superchargers. I believe I discussed this in the Engine Tuning Tutorial.
    The issue here is that we can't really duplicate the power drop or "Jag" in the power curve from blower gear changes.

    The point that I believe you are confusing here is that the static compression ratio really has nearly nothing to do with altitude performance.
    Note that the Merlin had a 6.0:1 compression while the Allison had a 7.0:1 compression but the big difference was that the Merlin got a better supercharger earlier and then a two stage supercharger while the Allison usually had only a single stage and smaller supercharger.
    Thus the compression ratio of a particular BMW 132 doesn't really tell you anything unless you know there is a historical link beyond what has been stated.

    Note also that maximum boost pressure or manifold pressure also doesn't have much to do with altitude performance.
    When the P-51A (Mustang Mk.II) got a two speed supercharger for its Allison engine, it had better altitude performance than earlier Mustangs even though the maximum manifold pressure was lower. The speed at Sea Level was lower because the maximum boost was lower but it could maintain that boost pressure to a much higher altitude (about the same as the Single Stage Merlin engines).
    Thus a 1.20 ATA versus 1.25 ATA is also no real indication of a more capable supercharger or better altitude performance.
    It is actually more likely an indication of improved engine parts and strength.

    Some Ju 52 manuals are available on the Internet without cost, but so far, I have not been able to find anything useful in the ones I have accumulated. They are listing engines in the 620 PS range and happen to be very early manuals. I would send you a copy of what I have, but it is a bit too large to email and really doesn't provide the information you want anyway.

    I checked in my copy of Jane's 1946, but found nothing at all on the BMW 132.
    I have a very similar need for information for one of my own potential projects at the moment.

    Regarding your comments about the kinds of engines I have been tuning:
    I have actually spent more time tuning engines for your projects recently than for my own projects!

    - Ivan.

  11. #136
    Hello Ivan,
    Thank you for your consideration and your preoccupation with this subject, not only
    regarding your reply but also your on-going support relative to the engines on quite
    a few of my projects.

    Iīve just been observing exactly what what you mean regarding the effects that different
    engine parameters like compression ratio and boost pressure have, or donīt have, on certain
    areas of the power curve during my current trials for the 1.25 ATA blower on the 725 Hp engine.

    Not everything had the expected effect, but I have understood it enough to be able to get the
    envelope quite acceptably close to the latest reliable data that I found.

    Even the discrepancy with higher altitude results compared to low altitude ones is getting
    better, as Iīve managed to improve propeller table 512 a bit more to get the normal operating
    performance better as well.

    As in your case, regarding information available for newer 800 Hp+ BMW132 engines, I have
    found no useful data other than Hp and RPM values, so I think a good way to go about it,
    will be to extrapolate data from the 725 engine, which is the newest one with reliable
    power-curve data that we have.

    In the same fashion data from the older 620 Hp and 660 Hp engines compares to the
    725 Hp one, extrapolations could be made for the 830 Hp one, perhaps arriving at a
    conclusion that a blower for this one could produce 1.35 or 1.4 ATA.

    Once I get the envelope for the 725 Hp engine nicely smoothened out, Iīll post the results!

    Certainly an interesting exercise, I must say!
    I hope your own projects will benefit from the information that you find searching around for
    my projects! In some cases, your and my projects seem to overlap to some extent.

    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  12. #137

    Acceptable results with strange graph shapes.

    Hello Ivan,
    The specified Max. Power and MP settings for the 725 Hp BMW132A-3, at S.L. and altitudes upto 7200 ft as posted a few days ago:

    1 min: - 2050rpm / 1.25ata - 725PS @ S.L.
    5 min: - 2050rpm / 1.13ata - 640PS @ S.L., 660PS @ 2952ft
    30 min: - 1975rpm / 1.06ata - 575PS @ S.L., 600PS @ 4600ft
    max. cont: - 1930rpm / 1.02ata - 535PS @ S.L., 565PS @ 5600ft
    cruise: - 1860rpm / 0.96ata - 485PS @ S.L., 515PS@ 7200ft

    I have managed to get some more or less satisfactory results by making adjustments to the propeller table 512, which however also included some adjusments to the torque graph, where I have put in a "hump" before the 2050 RPM point, in order to to increase Hp for the lower RPM settings. This "hump" is probably not very orthodox, and may be questionable.

    I found I could avoid it by compensating in Propeller Table 512, but the graph shape got very obnoxious, requiring a strange "valley" shape at J=0.4, also affecting J=0.6 a bit.

    The "valley" in Propeller table 512 looks just as obnoxious as the "hump" in the torque graph.

    Anyway, a summary of the results:
    Results at S.L.:
    ---------------
    Max. Power Hp and RPM are exact.
    At lower throttles, Hp results are exact, but RPM tend to be 60-70 RPM lower than desired.

    Results at 3000 ft:
    ------------------
    Max. Hp and RPM are fine at 2952 ft.
    5 min. power throttle is 9 Hp and 13 RPM low, but may be acceptable.

    Results higher up, upto 7200 ft:
    ------------------------------
    Hp and RPM tend to get progressively higher than desired with altitude, upto 34 Hp. and 200 RPM.

    Well, I suppose it was to be expected... I wonder if you would have any comments.

    Perhaps this can be regulated by reducing Boost Gain, which I havenīt tried yet.
    Possibly the increase from 1.2 ATA to 1.25 ATA, which increased overall engine power, would require an equivalent reduction in Boost Gain.

    Update: Reducing Boost Gain may be a way to fix the excessive power at higher altitude, but it may go against specs.
    Iīve just checked the model: Specs say full ATA is maintained upto 5900 ft, and in this case, MP starts going down a little before, just like on the 1.2 ATA model, so at least it canīt be said to be excessive.

    Cheers,
    Aleatorylamp
    Last edited by aleatorylamp; February 11th, 2018 at 10:20.
    "Why make it simple if you can also make it complicated?"

  13. #138

    Musings on Power Graphs

    Hello Ivan,
    Transferring the different ATA and Hp values given by the power chart values for the
    Ju52īs 725 Hp BMW132A-3 engine into the BMW132 Power Chart graph, I noticed that
    the graph angles are consistently not as steep as the existing ones.
    The performance graph refers to the BMW132 engines in the context of the FW200A Condor.

    So here, the airframe could be an extra factor to be taken into account.
    The power chart values for the 725 Hp engine are given in the context of the Ju52, an
    aerodynamically much slower aircraft than the FW200A Condor.

    The lower speed would allow lower RPM on the 2-pitch position props, and hence reduce Hp,
    which would presumably give a shallower graph angle on the performance graph for any given
    ATA value at any given altitude.

    Also, itīs a pity that there are no performance details for the 725 Hp engine for altitudes above 7200 ft, and for the Ju52 in general, so a lot of speculation is called for!

    The deduction exercise is then a bit more complicated than Iīd expected, but still, maybe not
    impossible...

    Update:
    At first, I thought that the A) unnatural looking "hump" in the torque graph, or alternatively the "valley" in table 512 which are needed to boost performance lower throttle settings (70-90%), and B) the higher performances that come out in the simulator for higher altitudes, could indicate that the data Iīm currently trying to use for the 725 Hp engine was wrong.

    HOWEVER, after inserting the performance data from the previous 1.2 ATA data into the performance graph, this made the graph angles far too steep to be of any use, so
    it turns out that the performance derived from the new data is after all, much more accurate, and makes for a more realistic flight model than before.

    Thus, it seems that a shallower angle on the performance curves would be correct for the Ju52, and would represent a feasible working hypothesis to go by.

    Cheers,
    Aleatorylamp
    Last edited by aleatorylamp; February 12th, 2018 at 02:43.

  14. #139

    New 725 Hp engine for g4e

    Hello Folks,
    Looking at the BMW132 power vs altitude graph, it is safe to assume that the BMW132A-3 engine worked with a max. manifold pressure of 1.25, delivering 725 Hp at 2050 RPM for take-off.

    Performance is as close as possible close to specification in as many positions along
    the curve as possible.
    Altitude performance is very similar to the previous .air file.

    Results, compared to manufacturerīs power chart S.L. - 7200 ft:

    1 min power: 100% throttle, 1.25 ATA
    ------------------------------------
    S.L....: 2052 rpm (+2 rpm), 725 hp (OK!), 165.6 mph (+0.6 mph)
    2952 ft: 2153 rpm ( OK! .), 771 hp (OK!), 173.5 mph (+1.5 mph)

    5 min. power: 89% throttle, 1.13 ATA
    ------------------------------------
    S.L....: 1971 rpm (-79 rpm), 639 hp (-1 Hp), 160.5 mph
    2952 ft: 2037 rpm (-13 rpm), 651 hp (-9 Hp), 165.3 mph

    30 min power: 84% throttle, 1.06 ATA
    ------------------------------------
    S.L....: 1903 rpm (-72 rpm), 575 hp ( OK! .), 154.9 mph
    4600 ft: 2028 rpm (+53 rpm), 612 hp (+12 hp), 164.8 mph

    max. continuous power: 81% throttle, 1.02 ATA
    ---------------------------------------------
    S.L....: 1865 rpm (-65 rpm), 539 hp (+ 4 hp), 151.6 mph
    5600 ft: 2023 rpm (+93 rpm), 590 hp (+25 hp), 165.4 mph

    Cruise power: 76% throttle, 096 ATA
    -----------------------------------
    S.L....: 1797 rpm (-63 rpm), 485 hp ( OK! .), 146.2 mph
    7200 ft: 2005 rpm (+145 rpm),549 hp (+34 hp), 163.1 mph

    Restly altitudes:

    10000 ft:
    ---------
    100% Throttle 1.02 ATA: 2177 rpm, 644 hp, 176.0 mph
    _83% throttle 0.90 ATA: 2053 rpm, 524 hp, 165.2 mph

    19000 ft:
    ---------
    100% throttle 0.72 ATA: 2073 rpm, 419 hp, 164.7 mph
    _83% throttle 0.63 ATA: 1956 rpm, 350 hp, 156.3 mph

    It isnīt perfect, but itīs as good as possible a balance achieved with micro-adjustments
    on tables 512 and 511, as
    well as a convenient Torque graph shape.

    Of course, as always, any suggestions will be welcome. If anyone were to be interested
    in seeing or should have
    the time and gumption to try out the.air file, I will gladly attach
    it to a post.


    Re: 830 Hp BMW132T-2 engine for the g5e
    Looking at the BMW132 power vs. altitude graph again, for this more engine of the g5e,
    it seems safe to assume that the manifold
    pressure for take-off power would be 1.35 ATA.
    I am adapting performance accordingly. As before, any warnings or suggestions will also be welcome!Thank you very much for your interest.

    Hereīs another screenshot of the g4e just for eye-candy.

    Cheers,
    Aleatorylamp
    Attached Thumbnails Attached Thumbnails CA+JY.jpg  

  15. #140
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    it's a very nice looking model, Stephan.
    well done.
    i'd say, yes, please post the new air file.
    sometimes the magic works.
    sometimes it doesn't.

  16. #141

    New Spanish Supercharger too.

    Hello Smilo, Hello Ivan
    Thanks, Smilo, for your interest! OK, hereīs the .air file for the g4e night flier, attached to this post!Remember, it is the 725 Hp version recovered from the Norwegian lake in 1986, at present in a Norwegian museum, very nicely restored!

    OK - now, apart from the other 830 Hp engine pending supercharger correction, the third model
    also needs supercharger attention: The Spanish CASA 352L.

    This Ju52/3m version has three Elizalde (ENMA) Beta B-4 engines, that deliver 775 Hp at 2200 RPM. They are Spanish licence-built American Wright Cyclone R-1820īs, just like the Russian Shvetsov M-25, of which the Spanish Air Force also had a number for their Polikarpov I-16 Rata/Mosca fighters.

    I have found no information whatsoever as to these enginesī manifold pressure, and upto now I had 1.2 ATA (34.87 inches Hg) for want of anything else, and it has worked quite OK.

    Nevertheless, I though Iīd try and get it better, even if actual model performance will stay the same. So, looking, I found a Power Chart, within a Wright Cyclone R-1820 Engine Overhaul Document - I canīt make head or tail out of it... so many different engine versions ranging from 575 to 1525 Hp... but I enclose it herewith. Perhaps someone can find some use for it!

    However, looking further, on an Air Tractor page I found a comment:
    Someone was installing a Wright Cyclone R-1820-72 on his M-A1B Air Tractor. Apparently this power-house was going to be a bit much for the crop-duster! 1200 Hp at 2500 RPM, manifold pressure of 45 inches of mercury, would be overdoing it a bit, I suppose...

    So, he decided to derate his engine to 900 horsepower, by limiting rpm to 2,300 and manifold pressure to 36 inches, for take-off and for continuous use. This way he was also going to increase its service life.

    Interesting piece of information... I could further derate this engine to give me 775 Hp and 2200 RPM. The numbers donīt tally absolutely exactly, so Iīll strike a mean between the two results:

    300 rpm less: 45 – 13.5 = 31.50 inches
    425 Hp less: 45 - 9.5625 = 35.4375 inches

    Average 33.46875 inches, the new Manifold pressure for the 775 Hp Elizalde Beta B-4.
    With a slight adjustment on the Torque graph, I can get exactly the performance needed!

    Would you think this could be a plausible, acceptable way of going about the matter?
    Opinions will of course be very much appreciated!

    Hereīs a screenshot of the Spanish Ju52/3m for more eye-candy.

    Remember, the attached -.air file is for the armed night-flier bomber/transport.

    Thanks again, and Cheers,
    Attached Thumbnails Attached Thumbnails CASA352L.jpg  

  17. #142
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    got it, thanks
    sometimes the magic works.
    sometimes it doesn't.

  18. #143

    1 Minute Take-Off Rating

    Hello Aleatorylamp,

    Have you thought about using the CFS WEP feature to address either the 1 minute or 5 minute power settings?
    You can't limit RPM that way, but it is pretty easy to limit Manifold Pressure.
    I have been a bit busy lately doing some research and causing trouble in another forum.

    - Ivan.

  19. #144

    WEP

    Hello Ivan,
    Well, I hadnīt thought of it... For some odd reason it hadnīt occurred to me.
    It would be a good measure to prevent people from just flying around at max. throttle
    all the time. It sounds like a good idea!

    Perhaps Iīll use WEP option 2, which is less ruthless and in case of abuse, wonīt cripple
    the engine to a clanking 50% power wreck - it just loses WEP.

    Also, it would seem logical to include the both 1-minute and 5-minute power settings into WEP.
    The power percentage or span involved is quite large, going from 89% to 100%, (1.02 ATA to
    1.25 ATA, i.e. 32.4 to 36.2 inches of mercury), so it seems quite worth while to do it that way.

    30-minute power is at 84% throttle, 1.06 ATA, 30.7 inches of mercury. Maybe anything above
    that should also be put into WEP.

    So the question is as of what power WEP should be implemented: 85% or 89%?
    I mean, if you were just going to stay at 88% for half an hour, it should really harm the engine
    as well, shouldnīt it?

    What would you suggest?
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  20. #145

    Spanish Supercharger

    Hello Folks,
    I think I missed something in my calculation for 33.47 MP for the Spanish 775 Hp Beta-B4 engine, derived from the Air Tractor with the derated Wright Cyclone R-1820-72 engine, that I had mentioned in my post yesterday.

    I did not take into account that the Air Tractor had a more efficient 3-bladed CV propeller installed. Consequently, the Beta B-4 would require a bit more than 33.47 MP to provide the desired 775 Hp, and now I am thinking that perhaps the original 34.87 (1.2 ATA) was more realistic.

    I suppose itīs splitting hairs here a bit, as it were, and the resulting pčrformance curve is of course the same. However, for the sake of technical accuracy, I want use the data that seems more correct. A basically identical engine would be the Wright Cyclone R-1820-33, but I have no tangible MP information.

    Anyway, I think Iīll use the 34.87 MP again, unless thereīs a different suggestion, so Iīm going to adjust the torque graphs accordingly.

    Then, for WEP, also for the other two models, itīll only be a matter of setting the manifold pressures
    once itīs decided at what throttle percentage WEP has to start.

    Cheers,
    Aleatorylamp
    Last edited by aleatorylamp; February 15th, 2018 at 04:55.
    "Why make it simple if you can also make it complicated?"

  21. #146
    Hello Aleatorylamp,

    It sounds like a good idea for
    WEP = 1.25 ATA and
    Normal Maximum = 1.06 (30 Minute Rating).

    As suggested earlier, that is how I would do it. There isn't very much difference between the 30 minute and max continuous anyway.
    The Supercharger boost WEP option is really pretty messed up, so you really have a choice of a 5 minute or 10 minute limit with water or water methanol injection.

    This kind of ties in with the discussions I have been having elsewhere:
    What happens when an engine needs Water Methanol injection for ANYTHING over its cruise setting?
    It may sound a bit stupid, but that is how the Japanese engines worked.
    I have an idea which is a little weird but need to test it out in an AIR file first to make sure there are no unintended side effects.

    - Ivan.

  22. #147

    WEP by Methanol-Water injection

    Hello Ivan,
    Thanks for confirming! Iīll go about it that way then.
    For practical purposes in the sim, I think it will be a simple and good solution.
    I expect that Smilo will also agree!

    Out of curiosity, I tested whether keeping the throttle at 85% would prolong WEP time allowed, but itīs the same 5 minutes as for 100%. Anyway, itīs partially realistic though, as 84% throttle was allowed for 5 minutes.

    What happens with water-methanol injection? I think the engine rusts! ...If used at speeds above cruising, I suppose it would possibly interfere with lubrication and maybe quickly ruin the engine.

    Itīs not such a stupid idea at all, actually, but do correct me if Iīm wrong!

    The impression I got was that interestingly enough, methanol performance increase came with the penalty of greater heat, so they injected water to cool that, also obtaining the added thrust of the steam generated. The drawback of all this was I believe greater corrosion resulting in reduced engine life-span, but for military purposes it wasnīt important.

    Later, the French did the same with their Turbomeca Bastan VIC turboprop turbines, with similar results, although here there was no methanol, just water. They were actually quite successful, and used them on the Nord 262 commuter/navy patrol aircraft for quite some time.

    Hereīs a screenshot of one I made for FS98. The lines are quite elegant. (Youīll say Eeek! A jet!!). The Americans modified a few of these with PT6 P&W Canada turboprops and called them Mohawk-298, for use by Allegheny Airlines for some years.


    Iīm curious as to what idea you may come up regarding water-methanol injection in the flight dynamics!
    OK then, cheers,
    Last edited by aleatorylamp; February 15th, 2018 at 11:51.

  23. #148
    Hello Ivan, hello Smilo,
    OK, the 3 aircraft now have engine performance curves based on the
    new one for the 725 Hp Ju52. The curves for the 775 Hp and 830 Hp
    versions are
    similar in shape, and proportionally more powerful, which
    is what was being intended. Also, they seem to be behaving themselves
    very well!


    The implementation of WEP after 84% throttle was no problem, and it
    feels much more logical to fly the airplanes this way.
    Thanks for reminding me
    about WEP, Ivan!

    So, quite soon Iīll be able to upload the three Antie Juīs.
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  24. #149

    Further to the Power Curves

    Hello Smilo, hello Ivan,
    For the moment, the power curves of the three engines (725, 775 and 830 Hp)
    are very accurate at
    S.L. compared to the specified maximum and cruise powers
    for S.L:
    All are exactly bang on +/- 0 Hp, except the 830 Hp engine which
    is 18 Hp low at 76% throttle.


    However, further up, there is some discrepancy with specs:

    _9-29 hp low at 3000 ft,
    _8-12 Hp high at 4600 ft,
    21-30 Hp high at 5600 ft, and
    34-43 Hp high at 7200 ft.

    Further up, I have no spec. data to go by.

    I was trying to figure out a way of evening out the consistent excessive power
    from 4600 to
    7200 ft in the specs, but could only come up with the idea of
    lowering Boost Gain a little, so as to reduce the excessive Hp at 4600, 5600
    and 7200 ft., but this is not possible:

    The RPM ranges involved overlap with the RPM ranges for 3000 ft, so any
    reduction to correct performance further up would further reduce performance there.


    The only thing that occurs to me is to either
    a) leave it that way, as for simming, a little extra power at the altitudes involved will be fine, or
    b) reduce power altitude power a bit the excess, at the expense of losing power lower down.

    Iīd vote for leaving it as it is, unless you would have a different preference.
    What would your preferences be?
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  25. #150
    SOH Staff
    Join Date
    Jul 2005
    Location
    State of Confusion..... -8GMT
    Posts
    3,758
    leave it as it is
    sometimes the magic works.
    sometimes it doesn't.

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