4f Is More Powerful Than 8f And Jubilee....

Discussion in 'TSW General Discussion' started by khalidaliishmail, May 14, 2023.

  1. khalidaliishmail

    khalidaliishmail Active Member

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    I've noticed the 4F maintains near maximum boiler pressure at around ~175 psi extremely well almost regardless of what its pulling/pushing. I compared its performance with the 8F and Jubilee with a given load. The 4F really is the little engine that could, the boiler seems to have incredible steaming capacity for its small size.

    Driving out of Liverpool Lime Street up the 1.1% incline with a single engine, (automatic fireman):

    Pulling 8x Loaded Limestone Hopper Wagons -

    The 4F managed to very comfortably attain 11-12 mph up the incline. Even with maximum 75% cut-off and the steam chest fully filled, the boiler was easily maintaining ~175psi with the safeties going off nearly constantly.

    The 8F with the same load could only manage ~7.8 mph. Boiler pressure dropped below 150 psi.

    Pulling 5x Loaded Mk1 Carriages -
    The 4F absolutely stormed out of Liverpool Lime Street. Had to back off quickly to stay within 15 mph limit. Up the 1.1% incline there seemed to be no holding it back and it was even able to break the 30mph speed limit reaching 32 mph. Boiler pressure never dropped below ~ 165-170 psi.

    The Jubilee managed to attain 27 mph at the end of the 1.1% gradient. Boiler pressure dropped below 150 psi.

    If somebody else could give this a try and see what you get or am I just driving wrong?

    For reference, here is a comparison of some of the key boiler specs of the three classes:

    Firebox Grate Area:
    4F 21 sq ft
    8F 28.65 sq ft
    Jubilee 31 sq ft

    Boiler Maximum Outside Diameter:
    4F 57.125"
    8F 68.375"
    Jubilee 68.375"

    Direct Heating Surface (Firebox):
    4F 124 sq ft
    8F 171 sq ft
    Jubilee 181 sq ft

    Indirect Heating Surface (Flues and Tubes):
    4F 1034 sq ft
    8F 1479 sq ft
    Jubilee 1470 sq ft

    Superheating Surface:
    4F 246 sq ft
    8F 245 sq ft
    Jubilee 331 sq ft
     
    Last edited: May 15, 2023
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  2. lcyrrjp

    lcyrrjp Well-Known Member

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    Good bit of research, and I’m not at all surprised. This is why I hope diesels will be introduced in timetable mode on both SoS and Chinley - Ambergate. It’s not that I’ve anything against steam, but at least the physics on the diesels is a rough approximation of the real thing. On the steam locos it’s completely unrealistic.
     
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  3. tft#6439

    tft#6439 Well-Known Member

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    How does that work if the 4F might as well be a tank engine!
     
  4. Lamplight

    Lamplight Well-Known Member

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    I have the same impression. Doing the banking services on Peak Forest, the 8F is losing boiler pressure as expected while the 4F chuffs along with the safeties blowing all the way. In fact, I don’t think I’ve managed to lower the 4F’s boiler pressure at all; at least not more than ~5psi.
     
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  5. OldVern

    OldVern Well-Known Member

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    The steam physics in TSW continue to be, IMHO, worse than those in Trainz! Got to wonder if Simugraph is really up to the task of calculating the infinite variables.

    Peak Forest is a great route and both visually and aurally the new 4F is very nice, but if the physics are so far off then it ruins the experience.

    I'm now going to have to dig around in TSC see whether there is one. Oh hang on, just found it...

    Train Simulator: Fowler 4F Loco Add-On on Steam (steampowered.com)

    Guess someone is going to have to try it out and do a comparison!
     
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  6. orb

    orb Well-Known Member

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    Well, I have that one on TSC, however I will have the 4F in TSW the earliest in some 7-8 months, so I can't really make a comparison of the two in similar conditions at the moment. By that time the physics in the TSW version may change. :P
     
  7. mattwild55

    mattwild55 Well-Known Member

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    Fully agree with this - there's something clearly wrong with the steam generation on the 4F. There's absolutely no way it should be blowing off while banking at full power and it seems to generate steam much faster than the 8F and the Jubilee under essentially similar conditions.

    Sorry for the tag DTG Matt DTG JD but can you confirm this is being looked at please?
     
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  8. DTG Matt

    DTG Matt Executive Producer Staff Member

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    Looking at some numbers, seems like the 4F is behaving correctly and the 8F is the one that's just not cutting it. I'll forward the findings on to our physics team :)

    Matt.
     
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  9. ollyweston350

    ollyweston350 Active Member

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    If that's the case I'd be interested to see how powerful the 8F becomes. I'd love some seriously heavy freight with that, even double headers
     
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  10. stujoy

    stujoy Well-Known Member

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    I don’t know about the 4F as I don’t have the route yet but I observed something about the 8F as I was driving up the incline out of San Bernardino in a scenario I made. At a cut-off of 22 I was happily climbing the grade and the boiler pressure was topped out with the safeties blasting away. Without adjusting the regulator and with no change in gradient, nudging the cut-off to 23 made the boiler pressure fall quickly to around half the maximum. It just doesn’t seem right that a small change on a continuous percentage scale should result in a dramatic change of behaviour. Unless the small change is at a point that triggers some other valves to open or something then I’m at a loss to understand it.
     
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  11. mattwild55

    mattwild55 Well-Known Member

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    Thanks. Does this mean that all of the freight trains will need to get significantly longer / heavier if the 8F is improved to a realistic performance level? I don't know what a prototypical load would have been for ICI limestone trains but the ones in-game at the moment do seem a little short.
     
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  12. khalidaliishmail

    khalidaliishmail Active Member

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    I have seen some mentions regarding the safeties on the 4F and an overenthusiastic AI fireman, but I think this is a different issue because even if the 4F boiler was maxed out being flogged within an inch of its life, I don't think it would be able to match, let alone exceed, the performance of the 8F and Jubilee. The 4Fs speed topping out at ~60 mph seems correct.

    From Train Simulator Classic experience I remember the 4F required cautious management of the regulator and cut-off in order to avoid running out of steam, particularly on gradients, whilst the 8F was a very noticeably more powerful, free steaming engine in comparison.
     
    Last edited: May 15, 2023
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  13. OldVern

    OldVern Well-Known Member

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    I think I would have to disagree about the 8F as it is being underpowered. When I did the assist mission on SoS, it took off like a Class 87 even with a dead Jubilee and train in tow. Certainly the 8F in TSC seems a bit more restrained and I had to nurse it all the way across The Port Road with an eight coach train, so I would expect the 4F should in reality struggle a bit more. Unless it can be proven otherwise the 8F certainly doesn't need more oomph, if anything it needs to be toned down a bit and it sounds like the 4F needs even more of a nerf.

    Haven't got round to buying the TSC 4F but as noted in the post above the performance there sounds like more reasonable expectation. And it should certainly not be constantly blowing off when being worked hard.
     
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  14. lcyrrjp

    lcyrrjp Well-Known Member

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    If DTG's conclusion from the findings in the OP is that the 4F is performing correctly and it's the 8F which is under-performing, then we're clearly just going to continue in the cycle of throwing more and more power into the locos every time someone complains - regardless of what the complaint is.

    All of the TSW3 steam engines over-perform in respect of their ability to maintain very high power outputs over long periods of time without losing boiler pressure. The 4F is just even more ridiculous than the other two. I look forward to the 8F producing performances equivalent to a Union Pacific Big Boy after the next round of tweaking.
     
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  15. OldVern

    OldVern Well-Known Member

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    ...which is why I'm now driving the Class 101 all stations from Ambergate to Buxton. Yes it's a little OP in full throttle in Gears 1 and 2 (just stay in Notch 3) but the performance otherwise seems spot on. If only we had the ability to set up our own all day timetable for this route...
     
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  16. DominusEdwardius

    DominusEdwardius Well-Known Member

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    So one thing that isn't entirely helping matters is the cutoff being shown on the HUD and reverser scale isn't *actaully* the cutoff the valves are set at, this is particularly notable on the Jubilee/8F.

    On the 8F/Jubilee
    HUD : Actual
    75% = 78.2%
    57% = 73.3%
    38.5% = 65%
    18% = 45.5%
    0% = 13.8% * (well it is actually effectively mid gear at that point)

    on the 4F
    75% = 71%
    56% = 61%
    37% = 41%
    18% = 23.6%
    0% = 11%

    So setting the reverser to 45% of the 4F is equivalent to setting the reverser to 18% on the 8F. As someone noted above this is reason why the Jubilee/8F seem to be super sensitive to changes at low cutoff... becuase it is.

    The 4F will only put down about 750HP consistently, you can get a little bit more if you are prepared to sacrifice a bit of boiler pressure but won't do for long. the 8F and Jubilee can put down a heck of a lot of power ingame once they warm up. One notable difference with the 4F and 8F is the setup of the firebox, the 4F starts off red hot (or probably more accuratle white hot) while the Jubilee/8F do not. There is a slight flaw in the Jubilee/8F while it heats up they do not generate a lot of steam at all which is why you get quite a lag before the darn thing starts steaming, they also to get the absolute most out of it require the firedoors to be wide open permantly. Once they're up to temp with the damper and firedoor wide the Jubilee/8F become ludicrously powerful, especially at speed where a core bug makes them even more overpowered the faster you get.

    So its quite a complex erm, matter really. The 4F is probably about right, while the 8F/Jubilee lie to you somewhat and do not steam well initially which give the appearance of them not being very powerful by comparison. However once they warm up, fired correctly and get up to speed they become an absolute monster.

    Should also note the 4F is a heck of a lot lighter than the Jubilee which naturally helps charging out of Liverpool, the 4F and tender combined weigh near enough 90 tons, the Jubilee weighs 133 tons, so 43 tons difference which is like having an extra coach and a bit less than the Jubilee!
     
    Last edited: May 15, 2023
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  17. Purno

    Purno Well-Known Member

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  18. OldVern

    OldVern Well-Known Member

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    I’ll have to look through the collection but certainly the one for sale on Steam, which dates from around 2010, isn’t shown as owned.

    I suppose at the end of the day, it’s nearly 60 years since anyone worked these locos “in anger” on real main line passenger trains and freight, so there has to be an element of compromise representing in a simulation - which also does not take into account factors such as wear and tear on individual locos, the fitness of the fireman/woman and the quirks of the driver. However I would rather have them slightly underpowered with decent balanced coal and water consumption than overpowered with the safeties constantly blowing. As we discussed previously about the top speed of the Jubilee, generally performance logs show these topping out at around 80 MPH with the power cruise on fairly level track in the high 70’s. They did not rag up and down the WCML at 95 MPH like a Class 86. Ditto the 8F. They were designed primarily for lugging Class E and Class F freight around at 30 - 45 MPH, not hauling away like a Class 66!

    One further thing to add about the 4F. Seems very light on its feet. Prior to starting my DMU scenario I was finishing up the Journey run where you have to load two rakes of limestone hoppers at Tunstead. With the second, 5 or 6 wagons being propelled back up the 1 in 90 gradient it was almost impossible to get the train moving. Dry rail, finger held down on the sander, feathering the regulator and brakes the 4F was constantly slipping. Not sure how heavy the consist was - maybe 200 tons but it seemed unrealistic that the 4F would be quite so light footed in that situation, given these locos were rated to take 245 tons unassisted up the 1 in 50 from Bath Junction to Midford (which also includes being able to restart on the gradient). So it seems to me the TSW steamers need more grunt and brute force at lower speed and less top end performance. But like I said, it’s all a bit theoretical and I guess we have to enjoy for what it is - a representation. But please, sort out the sounds on all three locos so that above 25 MPH the chuffs don’t just blur into an indistinct roar of white noise.
     
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  19. Doomotron

    Doomotron Well-Known Member

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    Yes, this is an upgraded version compared to the original one. I'm not aware of any physics changes but I do know it has additional light configurations and better textures.
     
  20. mattwild55

    mattwild55 Well-Known Member

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    A bit more context to this one following some more research: it appears that a prototypical load for 8F plus banker would have been around 16 loaded ICI wagons rather than the 8 (I think) we have in-game.

    The same source states that when the ICI hoppers were originally delivered, 4Fs were cleared to haul up to 11 loaded wagons.

    Additionally (and interestingly), apparently Class 40s were trialled during 1963 on the Tunstead quarry freight - another one to add to the list for that BR Green diesel pack?

    [​IMG]

    [​IMG]

    That might crank the challenge up a bit once the 8F is fixed.
     
    Last edited: May 16, 2023
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  21. Lamplight

    Lamplight Well-Known Member

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    Fascinating pictures, mattwild55. Thanks for sharing. Might I ask where they're from?
    That's an interesting formation :)
     
  22. mattwild55

    mattwild55 Well-Known Member

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    That last formation is from a time around the late 50s where piloting rather than banking was trialled - I think subsequently banking was readopted as the norm.

    The photos are from this collection by the Buxton railway photographer ER Morten, whose collection has been uploaded here:

    David Heys steam diesel photo collection - 52 - RAIL CAMERAMAN ER MORTEN (davidheyscollection.myshopblocks.com)

    It's a really spectacular collection of photos from the Peak Forest line with a lot of variety. It also shows clearly that the stopping passenger services on the line (Buxton shuttle excepted) would normally have been hauled by a 4P or later a 4MT (either tender or tank variant).
     
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  23. eldomtom2

    eldomtom2 Well-Known Member

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    IIRC the Academy 4F has steam chest simulation.
     
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  24. DominusEdwardius

    DominusEdwardius Well-Known Member

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    Should also note, that the ICI formations in the timetable are also running under capacity, with the services seeming to be about 70% of their rated capacity.
     
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  25. meridian#2659

    meridian#2659 Well-Known Member

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    I put 2 ici consists together. 16 of those wagons, got in real trouble on gradients with the 4f. I dont think this loco is overpowered. Not looked into the steam generation, so cant say anything about that.
     
  26. Lamplight

    Lamplight Well-Known Member

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    Sorry for the necro, but the 4F still rubs me wrong so I did some testing. Feel free to replicate this test since I’ll happily admit to not being the best steam driver.

    The test was this: Get up the Spessartrampe with a 500t mixed freight train. The consist in question is the loaded 15 car formation for the 4F. For those not familiar with German routes, the Spessartrampe is the 5.4km long gradient between Laufach and Heigenbrücken on MSB with gradients of 1.9-2.1%.

    The same consist was driven up the ramp with the 4F and 8F with manual firing and dampers at 25% (as per what was discovered to give the Jubilee more prototypical performance).

    4F
    Got up the ramp with little trouble. We were a fair way on the ramp before the boiler pressure even started falling. For most of the ramp, the regulator was fine at 100% with 65 and 75% cut off (65 to regenerate and 75 for power). The boiler pressure ended up settling at around 140psi. We reached the final curve of the ramp doing 16km/h.

    8F
    Struggled a bit. The boiler pressure was quick to drop on the gradient. I had to do some experimenting to get the loco in a somewhat stable state. In the end, what seemed to work was 35% cut off with 50% regulator. The boiler pressure settled at around 170psi and we reached the final curve doing 11km/h.

    Conclusion
    To be frank, there’s not terribly much I can do with this data since I’m no expert on steam. It seems odd to me though that the 4F hardly loses pressure while the 8F does as if she’s Swiss cheese in comparison. Maybe it’s the steam generation after all that’s odd about the 4F? I don’t know, but I’d like to hear what others here on the forums think about this.

    Also, keep in mind that this was me driving. It would be lovely if someone else did the same/a similar test to compare notes :)
     
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  27. OldVern

    OldVern Well-Known Member

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    It just sounds to me that the steam physics are way off. As regards the 4F all I can say is that according to the SIAM Bath Green Park game they were allowed 7 coaches south of Bath over the Somerset and Dorset unassisted (maximum gradient 1 in 50 or 2%) which is equivalent to around 280 tons at 40 tons each. 8F's never ran over the S&D and there is no real equivalent but the closest is either the Black Five/BR 5MT which were allowed 9 coaches or 340 tons and the 9F's which were allowed 11 coaches or 440 tons.

    So whichever way you cut it, the 8F should have outperformed the 4F in terms of haulage capacity and the ability to maintain a higher speed on the same trailing load.
     
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