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

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

Good looking results Bill 

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 ..........

Carl/Tread

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.

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

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

Later my friends

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

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!!!

Carl/Tread

MR

SMJ

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

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.

Johan

Bish

Thanks for the answer Bill about the wash / filters, very helpful

Yes very interesting info about the tracks but not knowing the answers my take is "Keep my mouth closed and the bowels open"  You do have me curious and will see if I can turn up anything.

That makes sense, i am still fairly new to wash's full stop, but i think it might be an idea to try an enamel wash and see what i think of them compared to oil's. No harm in giving it a try.

I know your as big a fan of Panzer tracts as i am so i can assume you have gone through your's. The 251 is my favorite vehicle, but i don't know alot about it mechanically, so i think i might look into that side of it more.

I'm wondering if pastels can be used as filters.

I think I overdid the filters on my Grant, making the light areas too dark.

Glad to be of help Rob!

Bish

Winetanker

Ye, i've got both those volumes. I could really do with reading through them properly, i usually just flick through looking for the info i need at the time.

Bill - Sorry i did not get here sooner....on the road from work.....As usual excellent dot filter work...love the weathering....the camo is "blended" nicely.

From an alternate firing position...

Rounds Complete!!

Bish

Mike

After letting the build sit over the week, I made some small adjustments to the washes and filters and then sealed everything up with a coat of Testors MM Lusterless Flat in the spray can. This removed any lingering traces of gloss and is the finishing touch to tie everything in the finish together as well as provide a nice flat surface to work on for the pigment weathering.

I applied a wet mix of Mig Dry Mud pigments by combining ordinary tap water with a drop of dish washing soap added to break the surface tension and the dry pigment powder. This mix was applied to the lower hull and suspension, tracks, and sprockets and allowed to air dry.

Using a combination of stiff bristle brushes and Q-tips, I removed the excess pigment until I had the look I wanted.

Then the tracks and sprockets were installed and some further adjustments made where I'd disturbed some of the previous results.

That just left a few little details to take care of like adding the reflective peel-and-stick mirror provided in the kit and adding some black artist pastels to the exhaust mouth. I used walk-around photos to inspect the finish and make some fine-tuning changes here and there before declaring this one complete!

Love it. Completly stunning build once again. I love the final look of the weathering.

Superb Bill. I absolutely love the camo and finishing. I always seem to say "this might be your best yet", but you continue to amaze me with each completed build. 

Thanks Bish glad you enjoyed the ride!

Eric

Stretch yourself, I don't see it???????

Excellent is still Excellent no matter how you cut it cowboy.

Mighty Fine my brother

Tony lee

wbill76

Thanks Bish glad you enjoyed the ride!

As always when its one of yours.

Another great project from Bill

Superb finish and blog as always ,Bill. I enjoyed this one and the discussion that went with it 

Great build, back to the New England game for me !

tread

I'm with everyone else here Bill ..........looks great ! Looking forward to following your next build .

looks great I think you have came up with the best finishing and  weathering technique  that i have seen

Tony

Tojo

Tread

Clint