DML Sdkfz 251/22 Ausf D COMPLETE! 10-14-12

Johan

Thanks for commenting and adding your input, no need to think you're out of your depth at all, much appreciated!

Bish

Have to agree with you regarding the unique nature of the 251...the only additional info I was able to turn up was that it had a 4-speed manual transmission and there are multiple control levers by the driver's station so I can only assume they are related to control of the tracks in addition to the transmission shift stick. As for your question on the oils vs. enamels...enamels are essentially oil paints that dry faster and are more durable. I use the enamels because they are convenient and have a faster work and cure time vs. the oils. Some believe that the oils offer a fine pigment grain and therefore a more sublte level of detail and manipulation but that in turn depends on the brand/type of oil paint you use more than anything else I think. I've nothing against oils myself and have a couple of tubes laying around but very rarely turn to them.

Great work as always Bill. Now my turn for a question. Is there a reason for using enamel wash and filtering rather than oil.

Some nice info on 251 tracks. The 251 is the only vehicle i now off that had a different number of links on each side, though i guess there may be others. I know one thing that was drummed into our heads is that our tracks had to be equal. I still don't quite get all the engineering behind the 251, but it certainly makes interesting reading.

Bill,

I am not very good with maths nor stats so...

I think you really hammered it with the dot filter and pin wash.

The effect is very convincing in both the darker as in the lighter areas.

My 2 cents would have been be to lighten the centre of the darker areas slightly, but honestly I think you achieved a better result as is.

And now my head cant let go...

Since the drive sprockets are the same size the velocity of the chain is the same so the ground speed is the same but since the shorter chain travels a shorter distance the chain itself will make more revolutions in a given time.

Think about it as an endless chain laid out in front of the vehicle.

If the drive sprocket was of a different size on each side it would be a different story.

My old dad would tell me of for commenting in an area out of my comfort zone so just tell me to SU :)

Thank you for sharing, excellent blog as usuall!

Very Best Regards

Johan

Carl/Tread

Now you know how I felt the last 6 weeks while enduring my Stats class!

MR

Glad you like the scheme! Late war patterns always offer something a little different.

SMJ

Appreciate the comments as always! This is one of the reasons why I pause at this stage instead of moving on to the pigment weathering right away. I like to take a set of walk-arounds and see things from different angles to ensure there aren't any little areas that escaped or adjustments that I missed. Thanks for the assist!

Bill: I really liked this before the weathering...she looks even better after!... The wash looks it little light on the front wheel fenders/ light and on the barrel near the shield.  Give it a second look.  Great work!!!

Love the paint job....nailed the late-war paint scheme...

Yes , i will have night mares now about track lenght's and angular velocities where a=pb +qc   .........................

Later my friends

Hey Bill thanks for the reply. 

I am pretty sure at this point the secret factor in this setup is the automotive based differential. We know most or many tanks have separate clutches and differential setups for each track or even three or more differentials inter-connected, I guess that since the half-track uses the truck based diff it is pretty much acts like when a car goes around a corner and lets one side roll at a different speed than the other. Thats all I can think of.

I did understand about the spacing you were talking about though. Thanks Bill

Hey Shell  ... the first thing I did was look up in my books the schematics from Jentz and Doyle on the Tiger I and KT .  The torsion bars are staggered, but the midpoint measurement between the 2 bars forms the centerline or pivot angle of the leading/trailing arms ..in other words, the wheels are in the same spot on each side, but they pivot from a different point but of an equal measurement from each other, which is different and more expensive to do than the half-track set up.... Jaysus ... i gotta go to bed... that was a mouth full

g'night guys

tread

Carl/Tread

, thanks as always! I think the point of confusion here is the distance between the sprocket and the first road wheel on either side and not the distance between the sprocket and the idler. As near as I can tell, the total travel distance on either side is the same when you measure idler wheel to sprocket. Using a metal ruler, the sprocket-to-idler distance on both sides of the model is approximately 9.5cm. The distance between the sprocket and the first road wheel on the left side however is approximately 1cm while it's 0.5cm on the right side...that's the effect of the off-set torsion bar design that I was referring to.

I'm not an engineer and can't say how the German design compensated for the different track lengths but per Panzer Tracts 15-2, the specification was 55 links for the left side and 56 for the right, so the real vehicle did have different track lengths as a standard per-spec feature. I do know that the front truck-style wheels were used for steering/guiding the vehicle and were not powered so don't know how that factors into things. Sorry I can't be of more help on that question. The use of different track lengths does seem to be limited to only the HT designs and not every HT had different track lengths (the 250 for example had the same 38 per left and right)...standard full-tracked vehicles typically had the same track lengths on both sides as you point out.

Can i butt in ? i was looking at a Tiger II and it also has leading and trailing torsion bars ......but the distance between the drive socket and the idler is the same ...that would make number of track links the same , right ? Is the set up on the Sd.Kfz 251 different ? I have the kit but i dont want to open it yet ..........

Good looking results Bill 

Heya Bill 

Sunday Night !   

The weathering process is looking really sweet  as always ,Bill

I Have a question again about the tracks and I have thought a lot about it.  I do understand the German design of their torsion bar suspension, or any torsion bar suspension, Regardless if it is a trailing arm/leading arm type or 2 offset trailing arms ( like U.S. and Soviet) ...If  one side has more tracks than the other, regardless of how many , the vehicle would not ultimately track straight to my way of thinking ( unless the differential could compensate for the different lengths of track)  On the other German designs with trailing/leading arm designs, the number of tracks is the same. I am not commenting really on your work, I am trying to understand a basic principle here, but mathematically it is not possible . Each side per one revolution of the drive wheel going a different distance. Constant corrections would have to be made no matter how negligible. The distance between road wheels to the drive wheel does not come into play , not even track tautness.The only way a different count on the tracks is possible is if wear and tear causes their ultimate length to each other to be different at which point of course all tracks must be checked for their proper to design specifications . I know driving the vehicle over poor roads / offroad and all, a driver could probably not notice 1 track.) as they are very short in length to each other, but other vehicles with longer length, it would not be possible.

Bill, I appreciate your thoughts 

tread

Thanks Rodolfo!

Rob

thanks for the comments as well! I add the dots straight from the bottle. When I mix up the DY mix, I create a large batch that I store in standard paint jars and then use on multiple builds. Since it's a "stock" color I use frequently it's just easier to do that way. I thin in the airbrush mix cup as needed instead of spraying from the bottle.

Winetanker

The simple answer is "whatever direction you want to streak in". I usually think about how rain/dirt would "flow" off the vehicle and then streak in that direction but keep it consistent for the surface so I don't have streaking happening in different directions. HTH!

Looking great, Bill....

I have a question about your dot filter technique, as well. When you have a flat surface, which way do you brush???

Have always really liked your wash / dot process and this one is right up there too, Very Nice   Not sure if it's the angles on the vehicle but that wash / filter really made this one come to life !

When you add your dots, are they straight from the bottle or are they thinned at all before application?

One reason I ask, you say you also use the pre-mixed dunkelgelb and I am guessing that this is thinned for your airbrush or do you mix up a new small amount for the dot filtering?

Excellent work friend!.  The camo looks very good!.

Regards!
Rodolfo

The fun thing about the weathering process is that it can totally transform the look of the previous paint work depending on how you go about it and what end result you want to achieve. I've been using reference photos of a surrender depot vehicle in Bohemia in 1945 and decided that a dusty appearance works best for my Pakwagen...so the following steps are designed to achieve that end.

First up I laid down an overall wash of MM enamel Raw Umber. The initial effect of course is that it darkens the finish but the real reason is to provide a foundation for the additional steps as the Raw Umber will get blended in with other colors and not left on its own.

Once that had dried, the next step was the application of dot filters using MM enamel Flat White, MM enamel Raw Sienna, and dots of the MM enamel 50/50 dunkelgelb/light gray mix I used to airbrush earlier on. The dots were applied in small sections at a time to avoid having the dots harden and begin to dry. Using a square-tip blending brush lightly dampened with clean thinner, the dots are worked in together along with the Raw Umber wash coat from earlier to create a filtered and streaking effect.

While the Pakwagen doesn't have a lot of raised detail or panel lines, there's enough there to justify using a pin wash to pull it out and deepen the finish. I used a thinned mix of MM enamel Burnt Umber and a pointed 10/0 brush to apply to the different areas and then came back with some clean thinner to remove any blooming and correct where needed. I also installed the Pak 40 permanently in place now that all the major manhandling is done.

Next up will be working on the pigment weathering for the lower hull, suspension, and tracks.

Well hello there Tony! Nice to see you pop in! School's going well, just finished up the Stats class (a real bear!) and started in on Ops Management this past Thursday. Counting it, there's only 4 more classes left and should be done at the end of March. Getting closer!

Sorry I haven't been around of late but I do check on you folks now and then.

The little wagon is looking nice my friend and by the way how's schooling these days?

Tony lee

Mike

thanks as always!

Tread

the actual vehicle had different track lengths per side...because the suspensions were different on either side (offset) in terms of the torsion bars. If you look closely you'll see that the distance between the sprockets and the first road wheel is different and that's why more links are needed. DML actually did a good job with the design of this family of vehicles in capturing that aspect.

Rambo

thanks for commenting and stopping by as well!

Rob

the reason that the 251 tracks are designed to be workable is down to the way they were actually designed on the real vehicle...they had the cap block trapping the links so DML really had no other option if they were going to design them as indy links. The reason you don't see workable tracks on the Magic tracks is down to the fact that DML would have to include separate track pin parts (2 per side) and that's another 400 or so parts depending on the type of vehicle you're talking about...and that equates into a lot of styrene! Some other manufacturers like Trumpeter have started including workable tracks in the kits so you never know...it could become the 'norm' for the future!

Carl

these are indeed the kit-supplied tracks. Thanks as well!

Bill them tracks look great .but ....they arent the kit supplied tracks are they ? You probably mentioned the answer already didnt you .............

Now your rolling along

You got me thinking after learning that these were workable tracks, wonder why the other tracks (magic tracks) were not made workable and these were?  I really like magic tracks but figure if they too were workable more people would go for the kits (not that they have a problem with that)

Looking great!

looking good can't wait to see her after weathering. Always liked half-tracks the Germans put everything on them. you could probably find a endless supply of variations that they came up with

looking great Bill..... in real life there would be same number of tracks ,right ?   other wise it would always be trying to turn in one particular direction... next up... weathering !

tread

It always looks good when the baby gets shoes. Looking good

Rounds Complete!!

Continuing on from last week's efforts, I finished up with the tracks. First order of business involved test-fits with the sprockets to see how many links were needed to account for the different suspension lengths on either side. Turned out that I needed 54 links for the left (shorter) side and 56 links for the right (longer) side. Because of the scale effect of the link parts' design and the lack of a movable idler to tension things, this means that the longer side is a little looser than the right but both sag acceptably so no cause for concern.

A quick trip to the spray booth and the tracks received a base coat of MM enamel Burnt Umber. I used strips of masking tape to hold the runs while painting to make life a little easier and ensure paint got into the visible nooks and crannies. Once that had dried, I dry-brushed some MM enamel Steel to create a metallic look followed by a wash of MM enamel Raw Umber to tie things together and tone down the Steel a bit. Final piece of work was to hand-paint the rubber cap blocks individually using MM enamel Gunmetal.

That brought me to the "hurry-up-and-wait" stage of applying the decals. I airbrushed a coat of Future to seal the base coat in preparation for the weathering stages to come and let it air dry for about an hour. Markings for the 251/22s were fairly limited based on available reference photos so I added some crosses to the hull sides and rear and also added the Wehrmacht license plate to the hull nose that seemed to be a common feature. Using the photo from Panzer Tracts 15-3 for the vehicle that I've been replicating in terms of interior details, I used the "number jungle" decal sheet that DML provides to create the plate number WH-1810156 out of individual number decals. Examination of reference photos show that the rear plates weren't a common sight so I left those off on the rear mud flaps. 

2nd coat of Future was applied to seal in the decals and it will now sit and cure thoroughly before the weathering process begins next weekend.

just looking in Bill .

Clay

SMJmodeler

wbill76: Hey Bill!  I've been real busy at work, thankfully, and haven't spent much time seeing what's on everyone's workbench.  I wanted to chime in so I could follow/enjoy your work.  Love the subject!  I hope to go back and read the whole thread but I do have a quick question:  What is the base color you're using on the interior?  Is the exterior color the same?

Thanks SMJ, glad you could stop by! The base color on the interior is the same color (for the dunkelgelb) that I used on the exterior...just treated/weathered differently. HTH!

wbill76: Hey Bill!  I've been real busy at work, thankfully, and haven't spent much time seeing what's on everyone's workbench.  I wanted to chime in so I could follow/enjoy your work.  Love the subject!  I hope to go back and read the whole thread but I do have a quick question:  What is the base color you're using on the interior?  Is the exterior color the same?

Thanks MR! Marc will be relieved to know you're not going to steal away his bride!