Tips and tricks from an idiot savant

[Heretic]

If 3D cabs really take off (or rather get the green light) in OpenRails, I might just dip into train sims again.

 

[ErickC]

They're already starting to come standard with some payware releases (namely 3DTrains and Dekosoft) and there are some Soviet locomotives that have them as well. I've been using a chopped-down version of my GP10 external model to test all the new cab features and figure out the processes. As-is, I have all controls, engine gauges, and the speedometer functioning. I am reading through the manual and there's a whole load of information to absorb. It's overwhelming, but has the benefit of transparency: they explain each parameter as well as the theory and calculations used. Imagine if we had documentation that thorough for ESP!

The new features are insane. You can add a freight animation as before, but you can also tell the sim how much the freight weighs, you can have it be static (always there) or continuous (loadable and unloadable with a setting for what is default in each car), you can use more than one (for, say, a double-stack car), and you can even unload coal porters in rotary dumpers!

 

[Heretic]

Motivation permitting, I might check out what Open Rails has to offer for the local market. MSTS did have some cool (sadly payware) retro lines from the other (i.e. my) side of the wall.


Still dreaming of a rendition of pre-war Berlin with all of its S-Bahn, U-Bahn, tram and bus lines to be ridden in first person. But there's no way in hell I can pull this off until I'm fish fodder.

 

[scottb613]

Hi Folks,

Personally - some my favorite features ORTS brings to the table are the AI improvements - you can have AI switchers making and breaking trains - have the road locomotive link up and take the train to its destination and reverse the process - AI helpers coming and going on hills without user intervention - some real improvements over MSTS... It's pretty amazing what can be accomplished when a sim is developed as a community labor of love without corporate budget constraints to consider...

Been meaning to try Blender myself... My modeling efforts are very crude compared to Erick's and a tad older... Largest US Consolidation ever made...

Regards,
Scott




Sent from my iPad using Tapatalk

 

[tgibson]

Looks nice, thanks. But I liked their Alco diesels better.

 

[ErickC]

Small post, relatively new technique for me:

It's a lot easier than doing it in an image editor. Faster, too, even though I'll have to take large screen caps and reduce the image size to maintain most of the original image's clarity...

Long way to go on this cab, though:

For this big old chunk of metal:

With any luck, it might pay for some books? College ain't cheap.

 

[hairyspin]

What a cunning notion! I shall remember that.

 

[EdMcCauley]

REFERENCES
Ebay. 20 bucks. It sits in my nightstand.

re: Your DC-9 Maintenance Manual
Wish I had one of these - no luck so far with eBay except multi-volume sets for $1,000 [sigh]...

Question for you: According to textbooks the "Angle of Incidence" of a wing is designated as "i(sub)wing" and defines the "Wing Reference Plane" aka WRP. I have a DC-9 diagram (front view) that depicts a downward-angled dotted line beginning outboard of the wingtip and ending at the wingtip. It is labelled "Wing Reference Plane." This appears to indicate that the WRP is a plane through the wingtip chord and root chord.

However, a graph of the DC-9 wing depicts the wingtip Angle of Incidence as -1.0 degrees, rather than 0 degrees per the above paragraph.

Given the fact that the angle of incidence varies along the wing semispan, I can't find an accurate definition as to the location of the WRP. Using the XY-plane of the designated aircraft coordinate system would seem to be the simplest method, but who knows what "tradition" has chosen.

Any help in defining this term would be GREATLY appreciated!

Tom

 

[ErickC]

On station diagrams, the wing reference plane is completely arbitrary with respect to any aerodynamic terms. On the diagram, the wing is depicted as it would be if it were flat and laying horizontally on the ground, without respect to dihedral (which shortens the wing span in terms of the overall dimensions of the airplane). The wing reference plane, you will notice, matches the dihedral of the wing. This lets you know that the actual wing is angled a few degrees and that the station diagram ignores the wing's dihedral. Therefore, you should build the wing flat, according to the station diagram, and then tilt it to the proper angle (this includes incidence as well as dihedral), or you will have inaccurate results (with the discrepancy growing with greater dihedral angles - simple trigonometry).

The incidence of the DC-9s wing varies as a function of span percentage, as an earlier post showed. The thickness does as well (it's not a linear relationship; there is a kink at the vortilon). The wing reference plane doesn't matter here, outside of its angles defining the wing's dihedral and incidence, because it's just a reference for the station diagram. Bear in mind that the variation of incidence of the airfoil is a function of skin contour, not wing structure.

 

[EdMcCauley]

ErickC,

Thanks for your reply!

On the [Station] diagram, the wing is depicted as it would be if it were flat and laying horizontally on the ground, without respect to dihedral (which shortens the wing span in terms of the overall dimensions of the airplane).

OK. The length of the wing on the STA diagram equals the length of the actual wing measured from fuselage to tip.

The wing reference plane, you will notice, matches the dihedral of the wing.

So the above diagram is correct, and the "Wing Reference Plane" is the plane from the Root Chord to the Wingtip Chord. The angle between the Wing Ref Plane and a horizontal plane is the wing Dihedral angle. One source I found states that the Dihedral for the "DC-9-50" is 1.5 degrees.

Tom

 

[EdMcCauley]

Building wings without guessing

Questions on the above diagrams...

1. Is this the DC-9-10 series wing?

2. The top diagram depicts the Angle of Incidence of the Zero Lift Line, not the chord. I don't think so, but is there any way to determine the Geometric Angle of Incidence from this chart? That's what I'm looking for...is this info available anywhere?

Tom

 

[EdMcCauley]

I think some of the diagrams posted in this thread are from this document: Does anyone have the entire "Aerodynamic Design of the DC-9 Wing and High-Lift System" by Roger D. Schaufele from 1967?

 

[Heretic]

1. Is this the DC-9-10 series wing?

https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-9#Specifications

2. The top diagram depicts the Angle of Incidence of the Zero Lift Line, not the chord. I don't think so, but is there any way to determine the Geometric Angle of Incidence from this chart? That's what I'm looking for...is this info available anywhere?

Couldn't find any definite data. Roskam has "N/A" for the DC-9-50*, but lists 1.3° for the MD-80. Assuming that the MD-80's wing really just got an extension (see DC-9 family guide**) from the -41/50 and that the incidence change between the -41/33/34 and the older models was 1.25 degrees, one may assume that the original -10/30 did have hardly any incidence, if at all.

* https://books.google.de/books?id=bJlZ4mKf1EkC&pg=PA146&lpg=PA146&dq=jan+roskam+dc-9+incidence&source=bl&ots=AWknzyFNN1&sig=48N01Ktbu7TE74eooPKhPegCWw4&hl=de&sa=X&ved=0ahUKEwiksd3gyZTYAhWRIewKHY2VBpAQ6AEIMDAB#v=onepage&q=jan roskam dc-9 incidence&f=false

** http://airlinercafe.com/page.php?id=396

I think some of the diagrams posted in this thread are from this document: Does anyone have the entire "Aerodynamic Design of the DC-9 Wing and High-Lift System" by Roger D. Schaufele from 1967?

I only have Schaufele's other paper ("Aerodynamic Design Features of the DC-9") as a PDF.

You can buy the other here: http://papers.sae.org/670846/

What do you want to do with all that data anyway?

 

[EdMcCauley]

https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-9#Specifications

1. There aren't any dimensions stated on the diagram. How can you tell if it's a -10 or not? I suspect it's the -10 because the diagram below it is designated -10, but the document also contains -30 diagrams.

Couldn't find any definite data. Roskam has "N/A" for the DC-9-50*, but lists 1.3° for the MD-80.

Thanks. That's the same info that I have.

I only have Schaufele's other paper ("Aerodynamic Design Features of the DC-9") as a PDF.

I purchased a copy from AIAA for $25, but my copy seems to be missing a number of diagrams that are referenced in "Aerodynamic Design of Transport Aircraft." I've notified AIAA, but they have not responded yet.

You can buy the other here: http://papers.sae.org/670846/

Thanks. That's where I found it for sale, but the price is $27. Having just spent $25 for nothing new, I was hoping that someone else had this one. Then I could find out if there was any data in addition to what was in "Aerodynamic Design Features of the DC-9."

What do you want to do with all that data anyway?

I have a 1/144th scale DC-9-30 kit that I'd like to improve. The wing shape is incorrect, so I'm compiling as much data as possible. If I can get enough information I'd like to scratchbuild a -30 in 1/72 or 1/48th scale.

Thanks for the info.

Tom

 

[Heretic]

1. There aren't any dimensions stated on the diagram. How can you tell if it's a -10 or not? I suspect it's the -10 because the diagram below it is designated -10, but the document also contains -30 diagrams.

Wingspan. The -30 and beyond all got wing extensions.

I have a 1/144th scale DC-9-30 kit that I'd like to improve. The wing shape is incorrect, so I'm compiling as much data as possible. If I can get enough information I'd like to scratchbuild a -30 in 1/72 or 1/48th scale.

Ah, nothing flight sim related then. I kind of hoped that you wanted to do something for one of the DC-9 renditions for flightsim use.

 

[EdMcCauley]

Wingspan. The -30 and beyond all got wing extensions.

The diagram I am referring to is in post 111. Span is only indicated as a percent value from 0 - 100%. The top chart is the zero lift line, and the bottom line is thickness distribution, both as a percentage of semi-span.

Ah, nothing flight sim related then. I kind of hoped that you wanted to do something for one of the DC-9 renditions for flightsim use.

That's a possibility. IF I can get the data.

Are you looking for someone to improve the appearance of the DC-9 renditions, or the handling qualities?

 

[Heretic]

The diagram I am referring to is in post 111. Span is only indicated as a percent value from 0 - 100%. The top chart is the zero lift line, and the bottom line is thickness distribution, both as a percentage of semi-span.

Thought you were still discussing the wing reference plane.

Judging from the remark about the -30 in the lower diagram, I'd say that this is indeed intended for the -30.

Are you looking for someone to improve the appearance of the DC-9 renditions, or the handling qualities?

Flight dynamics, mostly. Do you have any development experience in FSX?

 

[EdMcCauley]

Judging from the remark about the -30 in the lower diagram, I'd say that this is indeed intended for the -30.

The red text was added to the diagram by the poster. I believe that the "35%" comment refers only to the location of the vortilon on the DC-9-30. My experience is that unless the chart/diagram specifically states a different series, it refers to the -10. I *think* these charts are for the -10 because nothing is mentioned in the document regarding these two charts.

Flight dynamics, mostly. Do you have any development experience in FSX?

IIRC, "Flight Dynamics" in this case refers to the aircraft not responding as intended. e.g. Flying through the ground rather than landing.

FSX? No. Pre-FSX, yes; but it's been many years...

 

[Heretic]

The red text was added to the diagram by the poster. I believe that the "35%" comment refers only to the location of the vortilon on the DC-9-30. My experience is that unless the chart/diagram specifically states a different series, it refers to the -10. I *think* these charts are for the -10 because nothing is mentioned in the document regarding these two charts.

You can also clear this up by fetching good drawings of a -10 or -30 and measuring the wing thickness and chord and then comparing the T/C ratio with the above diagram. Since the -30's wing basically got a notable chord extension at the wing-fuselage-junction due to the slats (see Airliner Café's DC-9 guide), the resulting ratio should differ.

IIRC, "Flight Dynamics" in this case refers to the aircraft not responding as intended. e.g. Flying through the ground rather than landing.

No, not that. The rendition I'm using needs improvement in terms of aerodynamic. I doubt that a heavy DC-9-30 will still climb happily beyond FL350, if at all.

 

[EdMcCauley]

You can also clear this up by fetching good drawings of a -10 or -30 and measuring the wing thickness and chord and then comparing the T/C ratio with the above diagram. Since the -30's wing basically got a notable chord extension at the wing-fuselage-junction due to the slats (see Airliner Café's DC-9 guide), the resulting ratio should differ.

Still looking for decent DC-9-30 drawings.

The 6437 x 2638 version of this drawing will not download.
https://encrypted-tbn0.gstatic.com/...5JXN9ZxXOQ918GUKyiEbqtLKqflZV9rkyVtkrP0iSR3aA

Do you or anyone else have this drawing in its full size?

No, not that. The rendition I'm using needs improvement in terms of aerodynamic. I doubt that a heavy DC-9-30 will still climb happily beyond FL350, if at all.

The "real thing" will DEFINITELY not reach 350 at a heavy weight. You have to "step climb." Does the climb rate 'fall off' at all as altitude increases after takeoff? If not, then generated lift is not decreasing as air pressure decreases with altitude.

What is atmospheric pressure and angle of attack at 350? AoA should be in the stall regime.