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Post by nightowl702 on Mar 17, 2018 3:57:44 GMT
Hi all. I haven't been on the site for a while and I just barely saw the new 737s available. I downloaded the -300 and -500 and noticed that the fuel tank capacities are off. While all the 737 versions have the same fuel tank layout they do have different quantities. I serviced these aircraft for a long while so I am very familiar with this. At a normal fuel density of 6.73 Lbs/gal the 737-100/200 holds just over 9,500 Lbs in each wing tank and 15,500 Lbs in the center tank. The 737-300, 400 & 500 each hold just over 10,000 Lbs in each wing and 15,500 in the center tank and the next gen 737's, the -600, -700, -800 and -900 hold about 8,650 Lbs in each wing and about 28,900 Lbs in the center tank. Of course in the real world the actual weight of the fuel would vary. I have adjusted my aircraft fuel quantities as follows: -100/200 each wing 1428 gallons, center 2313, -300/-400/-500 each wing 1499 gallons and 2313 gallons in the center and for the next gen 737's 1288 gallons in each wing with 4299 gallons in the center tank. These are the basic model quantities and do not include -ER versions or any added aux tanks. Unfortunately I have long lost my cheat sheet and I didn't service them much so my memory on those is a little fuzzy. Some of you know how it is getting old! Hope you find this info useful. Happy Flying!
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Post by nightowl702 on Mar 17, 2018 4:58:53 GMT
Hi again guys. I just want to make a small correction to the above info. The 737-100 only holds about 12,500 Lbs in the center tank.
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Post by aerofoto - HJG Admin on Mar 17, 2018 7:10:11 GMT
Aircraft fuel configurations are often "specific to the requirements of various airlines" .... some aircraft among the same type/class (even fleet) varying quite considerably in these specifications depending on the routes their operators fly.
The configuration/s we've applied to the B737-300's, -400's, and -500's we offer is based on data we sourced "directly from BOEING" and which relates to just "one only" specification .... of which there are many.
Using any HJG simulation one needs to be mindful of the fact we "DO NOT" compile our aircraft in accordance with just sufficient payload and fuel to arrive at a particular MGW configuration.
Instead .... we compile "maximum/100% fuel and payload capacities" into all of our simulations (better for flight planners .... and which generally results in a nominal default overloading .... as one would expect under such circumstances) .... and the end user is then expected to reduce fuel, or payload, or both, strictly in accordance with the requirements of their actual flights whilst also ensuring that MGW limitations for each aircraft type are never exceeded.
Mark C
AKL/NZ
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Post by christrott on Mar 18, 2018 19:11:45 GMT
Mark,
I'm sorry, but your info isn't from Boeing and it isn't correct. The "baseline" 737-300/400/500 has a usable fuel capacity of 5,311 gallons or 35,584 pounds. Per the CFG, the HJG model has 6,506 gallons. This is not a valid fuel capacity for the Classic series aircraft. Per Boeing (http://www.boeing.com/resources/boeingdotcom/commercial/airports/acaps/737.pdf - Pg. 22-24) the maximum fuel capacity of a 737 Classic is 6,295 gallons with a 1000 gallon aft auxiliary fuel tank installed. Boeing never offered a forward aux tank on the Classics.
I don't have the book with me anymore, but the numbers given by nightowl are correct for the baseline 737 Classic series - 1499 gallons in the wings and 2313 in the center. This converts to 10,050 lbs in the wings and 15,500 lbs in the center. The aux tanks would add to the center tank value (so max of 3313 gallons).
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Post by aerofoto - HJG Admin on Mar 18, 2018 21:01:33 GMT
Well .... that's where we got it from .... and I can assure you of that. Precisely what BOEING page/data was used .... I can't answer .... because I (personally) didn't source it. I don't know if a "generic plan" or an "operator specific" configuration (since these can vary) was replicated either We won't be adjusting anything for now though .... simply because editing that data can bump other parameters to result in possibly negative performance/s (as "NIGHTOWL discovered) .... requiring other editing, then further testing, to correct and before we sign off on it ... but .... which can't be accomodated at this time. We'll look at it (remember these base packs are all V1.0 gestations at this time and we do often revisit our FDE's) .... but .... it'll be later rather than sooner .... since there's other priorities here at the moment. Thanks Chris  Mark C AKL/NZ |
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Post by christrott on Mar 19, 2018 0:32:54 GMT
The numbers you have for the 737 Classic are pretty close to the 737NG numbers, so it looks like whomever was doing the checking read the wrong pages.
Also, anymore there aren't really "Operator Specific" configurations. There are a limited number of options (like for the 737 Classic, there were 4 configurations - Base, 2cell Aux, 3cell Aux, and 4cell Aux. However, AFAIK, most operators either did the Base or 3 cell Aux, and about the only operators who took Aux tanks were -400 operators. The only -300s I've seen with the aux tanks are ones that are in Corporate service. I'm not aware of anyone who put Aux tanks in the -500 in normal service.
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Post by aerofoto - HJG Admin on Mar 19, 2018 5:54:36 GMT
As I recall (I'm focused on other simulations at the moment) .... ours are configured with L, C, and R tanks (a 3-tank configuration) only.
As I mentioned above .... we'll look at it, but, it'll be later rather than sooner .... due to those other priorities I hinted.
Mark C
AKL/NZ
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Post by nightowl702 on Mar 19, 2018 7:04:25 GMT
I have serviced multiple airlines 737's both classic and next gen. All the basic 737's have a 3 tank config, L,C,R as mentioned above. It didn't matter what airline it was all the 737CL's tanks held the same and all the 737NG's all held the same. The only variable I ever saw between airlines was if there were auxiliary fuel tanks installed or if it was a -ER model. I did have initial problems with mine after install but after re installing them they fly fine even after again adjusting the fuel tank capacities to what I have seen in the real world. I have modified many of my CFG files without issue but even so a screw up can occur as I had. For most people the tank capacities probably dont matter but since I have knowledge in this area I adjusted mine. But as stated above it is HJG's decision to make regarding any changes or further testing. My fuel capacity info was originally posted as just some useful info as to what I have seen in the real world.
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Post by Mike Monce - HJG on Mar 19, 2018 15:24:03 GMT
I was asked by Mark to look further into this. Unfortunately a lot of information doesn't seem to be available, unless someone can supply me with specific information...that would be appreciated.
The referenced documentation from Boeing (data for airport planning) doesn't list the specific loading for each tank, just the total capacity. The TCDS (U.S.) references an internal Boeing document that I can't find (D6-8734)that would probably give the values we are looking for. Maybe the TCDS from another country might give more info.
Let's take the -500 as an example. The HJG 500 has 3 tanks with a capacity of 6161 gallons. The airport planning document lists fuel capacities from 5311 to 6295 gallons depending on the engine and other factors which the document doesn't explain. The HJG capacity is exactly that listed for the upper limit of the 18,500 lb thrust engines and exactly in the middle of the two values given for the 20,000lb thrust engine which is where we set the thrust at in the simulation. So we are talking at best an error of about 100 gallons, if even that, in fuel loading. And that is not even clear without better data. Frankly I think we are picking nits here a bit. However, with better data we can certainly revisit this in the future as Mark said, but we are very busy with other projects at the moment. If people wish to adjust things for themselves then go ahead.
Mike
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Post by christrott on Mar 20, 2018 23:03:27 GMT
Mike, both nightowl and myself list the fuel capacities in our posts. These come directly from Boeing documents and in my case come from the American Airlines fueling manual and training materials.
Here is the pertinent information from my post. The fuel capacity for the baseline 737-300/400/500 is exactly the same.
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Post by christrott on Mar 20, 2018 23:06:37 GMT
As I recall (I'm focused on other simulations at the moment) .... ours are configured with L, C, and R tanks (a 3-tank configuration) only. As I mentioned above .... we'll look at it, but, it'll be later rather than sooner .... due to those other priorities I hinted. Mark C AKL/NZ You are correct that this is the way to label the tanks in FSX for the 737. There are no alternate configurations for the airplane baseline or alternate capacities of any of the primary fuel tanks. As referenced above, the only way to change capacity is to install auxiliary fuel tanks in the aft cargo hold, which has a separate panel and control system to the main one, so unless you want to model the aux tank panel, there's no need to really worry about this configuration. Also, I know FSX can't show it correctly, but by the Boeing documentation, the correct identification for the fuel tanks (on all 737 series aircraft) is #1 Main, #2 Main, and Center Auxiliary. |
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Post by aerofoto - HJG Admin on Mar 21, 2018 0:54:02 GMT
The like of this is a common FS limitation .... and that's just the way things sometimes are "in FS" unfortunately. The easiest way to do this is to retain the current configuration, but, manipulate the quantities .... "if" and "as" is necessary. The resulting revised configuration wouldn't be totally accurate, but, the combined total capacities would end up being truer to spec .... although something Mike mentioned above suggests there wouldn't be much of a change anyway, and as such, it's not going to change the way each simulation flies either .... and which I a god thing given the months of work that went into these B737 FDE's. I don't know how Mike feels, but, I personally, wouldn't be keen to add additional tanking since that can (potentially) screw-up the months of FDE work we applied to these simulations .... something I'm not keen to revisit .... not to mention the panel reconfiguration which you hint at too in regard to representing additional taking .... "if I'm understanding you correctly". In short .... these sorts of things border on some of the compromises that often need to made in FS   As I mentioned a couple of time now .... we'll look at it/this .... BUT .... later when it's more "convenient". At the moment nobody's majorly disadvantage .... if at all Mark C AKL/NZ
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Post by christrott on Mar 21, 2018 12:21:26 GMT
Mark,
I think you're misreading things here. All we're asking for is to change the tank capacities to the correct ones. There is no "additional tankage" being asked for. The current 3-tank configuration is correct, just the quantities are way off. In actuality, we're asking to REMOVE fuel from the airplane because it is currently nearly 1500 gallons above what the plane actually carries in the baseline 3-tank configuration and then redistribute it to properly have more in the wings than it does now.
It's going to mess with the CG of the airplane if the tank locations are off where they should be, but that should be the only change to the flight dynamics. If anything, it should actually fly better when fully loaded with fuel since it'll be lighter.
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Post by Mike Monce - HJG on Mar 21, 2018 13:57:34 GMT
I don't think we misinterpreted what was being stated at all.  We understand there are just 3 tanks. In my previous post I think I showed quite clearly that the stated capacities of the tanks is quite in line with published data from Boeing. The data below is directly from the pdf of the Boeing document (http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf )for the 500:
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| CFM56-3B1 ENGINES (18,500 LB) |
| CFM56-3B1 ENGINES
(20,000 LB SLST) |
| MAX DESIGN TAKEOFF WEIGHT
| 115,500 | 124,500 | 133,500 | 133,500 | 136,000 | USABLE FUEL
| 5,311 | 5,701 (2) | 6,121 (3) | 5,803 (4) | 6,295 (5) |
Now our 500 is listed at 133,500 lbs weight, 3 tanks, and 6121 gallons using the 20,000lb engines. Note the tank loading is exactly right for the weight of the plane. Note also Boeing lists that plane as having 3 tanks. Given the above data, a case could be made that we should lower the engine thrust rating to 18,500, then our 500 would be exactly in line with the above data. However we made that choice to also satisfy the need for the plane to behave reasonably well at flight phases. That also involves compromises with regard to the thrust curves in the air file which also affects the sound package, the cruise lift scalar, drag parameters, trim offset (air file), etc. etc. THIS IS A SIMULATION, and we have to work within the limitations of MSFS. It would be great to be able to do all of this and be exactly on spec with reality, but it is not always the case. Now, if a user wishes to change the design weight and then change the fuel loading to match the above data..go ahead! Just don't expect the plane to fly the same without other changes in the FDE. I'm also not sure how a "lighter plane flies better". What's the criteria for "better"? We spend much time getting the planes to fly as close to spec as possible in terms of Vr, Vref, runway takeoff length at MGTOW, climb rates, N1 @ cruise altitude, nose attitude at cruise, etc., etc. So what is "better"? Sort of reminds me of my other vocation: I referee youth soccer. There's always the parent yelling out about the calls. In a non-critical game my favorite technique is to stop the game, walk over to that parent, and hand them my whistle, and tell them "have at it!" and point to the field. The "deer in the headlight" look is amazing. If anyone wants to get into the nitty gritty of FDE, then please do so...it would be a great help to HJG to have another person work on these planes and we could probably make these projects move along a bit faster. Mike |
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Post by aerofoto - HJG Admin on Mar 21, 2018 14:43:19 GMT
I'm quite cognizant of what's being asked for Chris That's precisely what I stated when I replied above and as follows .... ALSO .... A careful re-read of my last will also indicate my "reluctance" (refusal would be a better term) to add, or move, any tanking .... and the only reason I stated that was in anticipation of someone else possibly raising such a matter in the future, so, it shouldn't be interpreted as a response to any matter so far raised Mark C AKL/NZ |
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