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World War II
Discuss WWII and the era directly before and after the war from 1935-1949.
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1/48 B-17F Build - 303rd BGs Luscious Lady
Redhand
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Posted: Wednesday, June 05, 2019 - 03:11 PM UTC
I actually have the Operation Familiarization Manual. It is so waterstained and paper thin and oxidized that it's really hard to read. Your post gives me the background.

I have a question you may be able to answer. On the R-1820, what was the design rationale for the baffles between the cylinders? I could never figure that out.

Thanks for any insights.

Dragon164
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Posted: Wednesday, June 05, 2019 - 06:36 PM UTC
Hi Brian,
I believe the baffling was to ensure the airflow went through the cooling fins.

Cheers Rob.
Redhand
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Posted: Wednesday, June 05, 2019 - 11:47 PM UTC

Quoted Text

Hi Brian,
I believe the baffling was to ensure the airflow went through the cooling fins.

Cheers Rob.



Rob,

That was all I could think of too, though I didn't come out and say it. I guess some engineers somewhere were tasked with deciding whether the "cost" of the flat surface and drag was outweigned by the benefit of having the air forced against the cylinder sides inside that NACA inspired cowling.

Brian
amoz02t
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Posted: Thursday, June 06, 2019 - 02:23 AM UTC
Wonder if you have this Graham White reference for engine development history?
Allied Aircraft Piston Engines of World War II: History and Development of Frontline Aircraft Piston Engines Produced by Great Britain and the United States During World War II
by Graham White
Reference page 23 cylinder head cooling and his B-17 application section


http://www.enginehistory.org/join_aehs.shtml
Redhand
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Posted: Thursday, June 06, 2019 - 02:31 AM UTC
No, but I'll check it out! Thanks.
Redhand
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Posted: Thursday, June 06, 2019 - 12:53 PM UTC
WORK IN PROGRESS

H.G. is nothing if not diligent! A major effort is going into making the first engine, the "black" "factory fresh" Wright Aero R-1820-97 that will be installed in the #4 (stbd. outer) position, most probably with an open cowling.

Here are pictures of the "actually pretty damn complex" Brassin engine being prepared for assembly.

A nice detail shot of the cylinders.



The rear of the same part.




One of the circular frames, the rear I think, though I could be wrong.



Parts of the ignition harness and spark plug lines.


A veritable collage of engine parts.



Non-kit test piece (note the 7 cylinders) testing out various paint configurations, with my "All Good" choices shown by arrows.



H.G. and I exchanged a lot of emails today trying to establish "the right look."

I expect we'll see many of these parts come together in a nearly complete engine pretty soon.
Redhand
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Posted: Thursday, June 06, 2019 - 01:27 PM UTC

Quoted Text

Seems to be a misprint in that manual as there is no such S/N that would be a B-17. More likely it is 41-24504 which would be the first B-17F-20-BO. Just a minor detail as you say, "Luscious Lady" is a B-17F-35-BO. Do you suppose we can get them to correct the E & M?

And by the way, great find! I have read through that manual who knows how many times but never noticed (or at least paid attention) that before!



Thanks for the correction. I snatched a hard copy of the manual at C-W when I was looking in their archives for that engine photo that appeared in the Roger Freeman Crown Publishers book. It's long misplaced, however, and I was lucky to find this pub as a free download online.

Working for THE Curtiss-Wright Corp. is what really sparked my interest in 1940s engine technology, including turbo superchargers. Of course, there was my father's own experience with radial engines flying everything from T-6s to KB-29s and KB-50s back in the day.

BTW, a guy named Greg has a really good YouTube Channel regarding WWII engine and airframe technology. You should really check it out. Greg's Airplanes and Automobiles
KPHB17FE
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Posted: Thursday, June 06, 2019 - 01:44 PM UTC
As long as he is having so much fun, here is an illustration of the prop governor and its related wiring and plumbing

Redhand
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Posted: Thursday, June 06, 2019 - 02:32 PM UTC

Quoted Text

As long as he is having so much fun, here is an illustration of the prop governor and its related wiring and plumbing




Oh man!

I'll pass it on!
Redhand
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Posted: Thursday, June 06, 2019 - 04:23 PM UTC
GETTING THERE

Here you can see the heart of the engine kit with various shades of "black" intended to mimic the appearance of the real thing (or at least one of them).


I felt it was necessary to have multiple dark shades to reflect the different textures and colors of the components.

Here we are getting much closer to complete, though there are MANY details left to be finished.



I'm pleased with how it's coming along!

KPHB17FE
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Posted: Thursday, June 06, 2019 - 10:49 PM UTC
Lookin' good! I have a couple sets of those engines but have not had the courage to take them on. I'll watch here
Redhand
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Posted: Friday, June 07, 2019 - 02:35 AM UTC

Quoted Text

Lookin' good! I have a couple sets of those engines but have not had the courage to take them on. I'll watch here



I had the same reaction to the Brassin set when I first got it. "Way cool!" But on closer examination the intimidation factor set in. They really are beyond the "some modeling skills helpful" level.
Joel_W
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Posted: Friday, June 07, 2019 - 05:01 AM UTC
Brian,
At the rate that you and HG are going, you'll have all 4 engines done sooner then later.

Those ignition harnesses are amazing. Measuring each wire against the PE part really is paying major dividends now.

Joel
Redhand
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Posted: Friday, June 07, 2019 - 11:16 PM UTC
MORE ENGINE DETAILS

Here we see H.G.'s work on the 1/48 propeller governor.



With this closeup.



Compared to the real thing on at least one engine.




I remain somewhat mystified by how this thing works. The props are Hamilton Standard "Constant Speed" propellers, which means that hydraulic fluid feeding the propeller dome "automatically" adjusts the blades' angle of attack to maximize aerodynamic efficiency at the engine's rpm setting (while minimizing fuel consumption). Or some such. And indeed on this governor control, there is piping at the bottom. However we see the flywheel with the control cables leading to one of the baffles, and the tech literature confirms that these cables lead directly to controls in the cockpit.

So it's obvious there was pilot input into this "constant speed" system. But why, if the system is supposed to be automatic? I think we're stuck in WWII technology where "automatic" really means "partially automatic." It's a puzzlement, or I betray my ignorance as a non-pilot who should "Keep yer hands out of the cockpit!"

Finally, below is another picture of the WIP engine. The gloss black rocker arm covers on the cylinder heads are a nice touch.

Joel_W
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Posted: Saturday, June 08, 2019 - 12:44 AM UTC
Brian,
The detail work on the engine is simply beyond anything I've ever seen. The pulley system's cable even has a realistic slack to it.

As far as the manual cable override of the auto pitch control, could it main function be for when the aircraft is idling and stationary? I'm sure that Karl has the answer or a really very educated guess.

Joel
Redhand
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Posted: Saturday, June 08, 2019 - 01:09 AM UTC

Quoted Text

Brian,


As far as the manual cable override of the auto pitch control, could it main function be for when the aircraft is idling and stationary? I'm sure that Karl has the answer or a really very educated guess.

Joel



Perhaps the good, old-fashioned manual override way is preferable to "fully "automatic," when we consider a more recent Boeing product - the 737 Max.
KPHB17FE
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Posted: Saturday, June 08, 2019 - 01:46 AM UTC
I will see if I can explain this (sort of ). The cable you see controls spring tension on some rotating flyweights. This controls the amount of oil going to the prop. As the speed varies, the flyweights change position which in turns varies the amount of oil flowing to the prop. Inside the prop dome is a piston which controls the mechanism to control the pitch of the prop. Hard to explain but trust me, it works fine and it is wholly automatic after it is set. One of the lines you see in the photo I posted before is for normal oil to the prop. The other line is from the feathering pump. The electrical connector is for feathering. When the feather pump is on, the pressure bypasses the governor and goes direct to the prop dome, driving it to feather. When the pressure reaches a certain point (400 PSI comes to mind), the feathering pump shuts off. To unfeather, you hold the feathering button in (to bypass the earlier switch) and when the pressure builds up to 600 PSI, the prop unfeathers (the oil pressure is directed to the other side of the piston using a bypass valve). You can then control it normally. The one in my photo has an external line for supply so that is probably a -65. This diagram is from a B-24 manual and has an internal supply which I think is what the 1820 -97 had. I am too lazy to look it up right now. Anyway, the system works the same on both airplanes. EDIT: The dash 97 has the external supply line. That's what I get for trying to work from memory!



What can I tell you, the B-24 manuals have some great illustrations (auxiliary is pressure is from the feathering pump):



One more:

Redhand
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Posted: Saturday, June 08, 2019 - 01:56 AM UTC

Quoted Text

and it is wholly automatic after it is set.



Thank you Karl! If anyone knew in this day and age, I knew it would be you! And I see that human input was required to "instruct the system what to do," i.e., full flat pitch on takeoffs, etc.
KPHB17FE
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Posted: Saturday, June 08, 2019 - 02:03 AM UTC
On the B-17, the lever on the control stand was connected to the cables and pulley, that was how RPM was set. Then the flyweights kept it as set automatically. On the B-24, there was an electric motor to control the flyweight tension. And this is totally different from electrically controlled props. We won't even get into that!
Joel_W
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Posted: Saturday, June 08, 2019 - 04:41 AM UTC
Karl,
You're a wealth of knowledge that most likely no one else can come close to.

In many ways you remind me of Steve Zologa who started as an armor modeler, and a member of the LI Scale Model Society; a chapter of IPMS region #1. His models were far beyond what the mortal modeler could do as he researched everything to the nth degree. Slowly but surely he stopped modeling and just researched and studied armor. The rest is history as just about everyone I use to know in region #1 deferred and referred to him .

Steve has written books on WWII armor, and has been on the History channel numerous times when the programs deal with WWII Armor.

You're his equal when it comes to B-17s for sure.

Joel
Redhand
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Posted: Saturday, June 08, 2019 - 10:55 AM UTC

Quoted Text

On the B-17, the lever on the control stand was connected to the cables and pulley, that was how RPM was set. Then the flyweights kept it as set automatically. On the B-24, there was an electric motor to control the flyweight tension. And this is totally different from electrically controlled props. We won't even get into that!



It's starting to become clear to me now. Of course those controls would be on that console between the pilots!

You are right that the Curtiss Electric props are a different animal. Angle-of-attack on the blades and feathering was powered by an electric motor in the hub, not hydraulic pressure.


I understand that they were preferred in combat because there was less to go wrong if one had to feather an engine. An oil leak in a Ham Standard system due to battle damage was a greater risk than electrical failure in the hub motors. That's why the B-29 atomic bombers had Curtiss-Electric props., etc.

But I digress and stray off topic.


KPHB17FE
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Posted: Saturday, June 08, 2019 - 12:33 PM UTC
Ah but: Part of what caused the legend of "One a day in Tampa Bay" with the B-26 Marauders was the electric prop. Apparently they didn't always get the best maintenance or parts at the training bases. SO batteries were not maintained and on take-off, where the props were putting a big demand on the electrical system, the batteries were not providing enough back up and the props would go to a flat pitch. Prop not moving any air backwards, airplane not go forward... Airplanes will always figure out new ways to kill you.
Redhand
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Posted: Saturday, June 08, 2019 - 04:24 PM UTC

Quoted Text

Ah but: Part of what caused the legend of "One a day in Tampa Bay" with the B-26 Marauders was the electric prop. Apparently they didn't always get the best maintenance or parts at the training bases. SO batteries were not maintained and on take-off, where the props were putting a big demand on the electrical system, the batteries were not providing enough back up and the props would go to a flat pitch. Prop not moving any air backwards, airplane not go forward... Airplanes will always figure out new ways to kill you.



They were not without their problems.
Redhand
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Posted: Saturday, June 08, 2019 - 04:52 PM UTC
READY FOR THE TEST CELL!



Hot off the production line:





I literally could not have done it * * * any better myself (attempt at subtle humor ) Seriously, I doubt I could have pulled this off.

And here are some views of the engine test fit to the wing.





But it's real home is the #4 engine position.







If you are wondering about the holes in the background styrofoam, there's a reason.

We are planning three "aluminum" Studebaker engines for the rest. The weathering on each will be different, to suggest different phases of the engine's service life. And some will have aluminum ignition wires, others brass. The numbered holes will keep them from getting mixed up.

I hasten to add that H.G. is not yet finished with #4. It also has to be weathered, even if "new"; and there are many additional details to be highlighted and completed still.

Moreover, H.G. specifically asks me to point out that:


Quoted Text

Back ring needs to be put on but I'm flipping a coin as to if that should be done now or at the time each engine is test fitted to the plastic. There will be plenty of handling at that time. But this will do for now and after they are all mounted the gloss black will touched up. Of course the shaft has to be removed yet it makes a great handle to hold them. ALSO, and this is a huge one, if I find a way to make this one look better as we progress then it will be done. For example, I know there are very fine wires that have the braided look which are made for bike models. [Please] mention * * * that if an improved version can be done then this one will be dismantled. Yeah I plan for that.



As someone who ripped out the nose of this model and completely re-did it, I can relate.
KPHB17FE
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Posted: Saturday, June 08, 2019 - 10:05 PM UTC
That's a beauty!