Calling all Iowa-class (BB-61) fans

[Aur]

Aur (DavidP),

My mistake - I should have gone to the link you provided. Those props look very nice, indeed!!!

OK, here are two of the three dimensions you requested:

Shaft (metal) diameter - 0.095" (2.43mm)
Base of Center Hub (of my metal replacement screws) - 0.19" (4.826mm)
The depth of the shaft hole in the center hub I can't measure as my shafts are already in place - BUT - I would make them No Less Than 1/8" deep as you should have room to drill out the hub at least that amount. Perhaps 3/16" might even be workable.

Hope this helps,

Hank

Thank you very much for taking the time to measure the parts for me. I think I'll just make the shaft hole as deep as the design allows, as this would also save material and reduce final price.

I'll let you know how the design works out.

Thanks again,
Aur

[bigjimslade]

This is what I got working off the original plans for the Iowa and NJ. I wonder how close the Tamiya and Trumpeter kits are, especially considering how off their hull shapes are.

I realized that i had posted the wrong propeller. (So many propeller files). So I have edited to show one from the NJ/IA.

The point of posting this is to illustrate how sharp the edges are. If you made this into 1:200 scale it would be sharper than a razor blade.

So you have to do some overscale for modeling.

[BB63Missouri]

If you go to Page 134 on this site, about 3/4 way down the page, James M has some links listed. Open up the link for USS Missouri 1944 and there is an excellent view of the propellers. The shape of the blades is very clear. I don't think they are as thick as the David P example and are different shape to bigjims. I hope this is constructive and helps to get props as accurate as possible.
David

[bigjimslade]

If you go to Page 134 on this site, about 3/4 way down the page, James M has some links listed. Open up the link for USS Missouri 1944 and there is an excellent view of the propellers. The shape of the blades is very clear. I don't think they are as thick as the David P example and are different shape to bigjims. I hope this is constructive and helps to get props as accurate as possible.

I posted the wrong picture. Edited for the correct one above. He is an example of the prop blade profile.

[Aur]

Yes, the actual propellers are different from the designed one. The inner ones were originally 17'. Then redesigned at 18'. The actually installed ones were 18'-3".

Although you've edited your post, I've put it here as a reference.
I'm curious about how you got the 18'3" diameter of the 5-bladers. I used War Service Fuel Consumption of U.S. Naval Surface Vessels and David Taylor Research Center First of Class Trials documents of the USS Iowa as my reference, and they both have the inboard 5-bladed screws as 17ft. The former has the data from 1943-1944, and the latter from Iowa's August 1985 sea trial, after her modernization. It also notes that Iowa (in 1985) was equipped with the same screw configuration as that on New Jersey in 1943. I don't know if any of the Iowa-class ships ever had their screws changed, but from what I could gather, they seem to be the same since WWII.

As for your updated photo, that looks really good! Do the original plans include blade and hub outlines? And did you use the cross section profiles to construct the blades? The CAD software you have is certainly much more superior to what I use - Autodesk 123D Design. This has rather limited ability to handle complex shapes of the screws apart from limited 3D tools, so I had to adapt and adjust many things. Even so, Steve (Model Monkeys) managed to make magic with his designs using the same program.

The Shapeways render shows the design after the blades were thickened for metal printing. They require the design to have a minimum thickness of 0.8mm, so this is the best it can look to be printable in brass/bronze materials. On the other hand, the design for frosted detail plastic printing would have much thinner blades (just like the 3D pics in my thread), as the minimum thickness allowed is 0.3mm (and even less for areas like blade tip and the pointy hub cap). This is an option for those who wish to have a more to-scale version and do the paint work themselves.

For my design, I drafted the blade outline directly from this photo, along with additional adjustments from many other: http://www.navsource.org/archives/01/063/016300h.jpg

Regards,
Aur

[bigjimslade]

They have hub outlines but no blade outlines. You have to make the frames, position them, calculate the rotation, and derive the outline from that. The 5-blades are 17. My misteak. THE outboards are 18-3 and were 17 and 18 at one time in the design. I would post those but, unfortunately, when I went to NARA for that, the printer was not working so I had to take screen pictures with a camera. So it takes a huge mosaic to see the thing.

Note that what I have here would take a lot of modification to be used in a model,

[Aur]

Hi guys,

I came across a problem while working on the new measurements from Hank. I was aware just by looking at a glance that the Trumpeter screws have narrower (smaller) hub bases than the Tamiya ones, but I didn't know it would be as much as 1.124mm!!!!! (Tamiya diameter converted to 1/200 scale)
I'm now suspecting the Trumpeter part diameter to be too small compared to the Tamiya part, drydock photos, and also bigjimslade's model in the screenshot. If you based your design on the original drawings, then I'm sure Trumpeter is the culprit (as always).

If you happen to have the exact diameter of the actual hub base, please let me know it. The diameter of the strut bearing should also work, but it, too, has to be accurate.

Now the problem is deciding whether to design it inaccurately to fit the Trumpeter parts, or follow the correct measurement, meaning that modelers will need to modify the struts themselves. Another option would be designing additionally the whole struts as separate parts included in the set, so the screws can stay correct. Lots of work if that were to be the choice. I've come up with other plans as well, but any thoughts about this would be appreciated.

This is a screenshot of the disaster:

(Left is the Tamiya diameter, right the Trumpeter, both in 1/200)

Aur

[BB62vet]

Aur,

The hub diameter I posted (0.19" dia.) was taken off the set of props I purchased from Keith Bender back in 2015 - I think he machines his brass props from the actual USN engineering blueprints, but it's just a guess. Here is a comparison of his (brass) props vs the Trumpeter kit props (plastic) and Trumpeter Add Ons (metal):

Hope this helps,

Hank

[Aur]

Hello Hank,

Could you please measure the Trumpeter parts' hub diameter, so I could compare it to Keith's? I also noted that Keith made the hub cap noticeably shorter and smaller towards the tip than the kit parts, and in actual photos it appears to be the same, but I can't say for sure since it's too unclear. I would appreciate bigjimslade, or anyone else who could offer the measurements of the hub from the original plans. Scan of those specific plans would be even more useful, if it is possible. If I have the hub outline, most of the problems would be solved.

Also, Floating Drydock has drawings of the screws for sale, and I would like to know if anyone knows what's included in there and the accuracy of it.

Bu-BB61-14 USS IOWA CLASS1942 5 BLADE PROPELLER (Inboard) VAR$14.00
Bu-BB61-15 USS IOWA CLASS1942 4 BLADE PROPELLER (Outboard) VAR$14.00

Their website: http://floatingdrydock.com/Bu.htm

Regards,
Aur

[bigjimslade]

Aur, would the Booklet of General Plans for the Iowa class or Warship Data #3 USS Iowa be of any use to determine the hub dimensions?

This is what I extracted from the microfilm.

The Booklet of General plans is not suitable for measurements in nearly all cases. They are like the maps in amusement parts: they show where things are relative to each other but that it is. They are highly imprecise and in many cases wildly inaccurate.

[Aur]

Aur, would the Booklet of General Plans for the Iowa class or Warship Data #3 USS Iowa be of any use to determine the hub dimensions?

I checked the first one, and it appears to be a little too crude to measure. The other one isn't available online. Thanks for the suggestions, anyway.

This is what I extracted from the microfilm.

Screen Shot 2018-01-24 at 1.17.31 AM.png

I did the math for this, and turns out, it is 5.72 mm in 1/200. At 5.95 mm, Tamiya wins over the Trumpeter and Keith's part!
Since I eyeballed the hub shape for my 1/350 version, I would design a new hub in accordance with your extract.

@Hank, if you would, please measure the plastic strut bearing diameter, in case they are different from Keith's hub base. In the photos I have, the screw hub base appears to be slightly larger than the strut behind it, so if the strut isn't too small, then there is no need to adjust the screws.

Aur

[BB62vet]

Aur wrote:

@Hank, if you would, please measure the plastic strut bearing diameter, in case they are different from Keith's hub base. In the photos I have, the screw hub base appears to be slightly larger than the strut behind it, so if the strut isn't too small, then there is no need to adjust the screws.

Aur - I already have the shafts in place on the hull. I can't give you an inside diameter. Sorry!

Hank

[Aur]

Aur - I already have the shafts in place on the hull. I can't give you an inside diameter. Sorry!

Hank

Hank,

My apologies if I mistakenly indicated the part....I was referring to the outer strut section here:



Would this be possible to measure as attached on the model?
I'm just wondering whether this will be different from the hub base of the kit or Keith's.

Thank you very much,
Aur

[EJFoeth]

Also, Floating Drydock has drawings of the screws for sale, and I would like to know if anyone knows what's included in there and the accuracy of it.

Bu-BB61-14 USS IOWA CLASS1942 5 BLADE PROPELLER (Inboard) VAR$14.00
Bu-BB61-15 USS IOWA CLASS1942 4 BLADE PROPELLER (Outboard) VAR$14.00

So funny they actually sell those drawings; completely missed them.

[Aur]

Also, Floating Drydock has drawings of the screws for sale, and I would like to know if anyone knows what's included in there and the accuracy of it.

Bu-BB61-14 USS IOWA CLASS1942 5 BLADE PROPELLER (Inboard) VAR$14.00
Bu-BB61-15 USS IOWA CLASS1942 4 BLADE PROPELLER (Outboard) VAR$14.00

So funny they actually sell those drawings; completely missed them.

Indeed! I wonder what is included in there. If there were blade drawings, cross sections, hub profile and such, then that would be interesting. I don't think someone would have these plans in hands though...considering their usefulness in general model making.

[EJFoeth]

I'd expect that these drawings contain all the info to make a good 3D model, including sectional information (table of offsets). Proof of the pudding is in the eating...

[Aur]

I'd expect that these drawings contain all the info to make a good 3D model, including sectional information (table of offsets). Proof of the pudding is in the eating...

Who's the first to taste?
It's also interesting because the plans are instantly delivered online...
Edit: not sure if they do online sending. I might have to email them about it.
I'll look into it.

[bigjimslade]

I'd expect that these drawings contain all the info to make a good 3D model, including sectional information (table of offsets). Proof of the pudding is in the eating...

I'd wager you get a full set of cross sections and have to calculate the twist yourself. The cross sections on the Micro film show offsets and distances as in the sample I posted previously.

[Builder 2010]

The prop shaft is 23" in diameter if that helps. I had more information about the bearing sizes, but can't find the very old post on WorldAffairsboard.com.

[BB62vet]

Aur wrote:

Would this be possible to measure as attached on the model?
I'm just wondering whether this will be different from the hub base of the kit or Keith's.

OK, got it! I'll get the micrometer out tonight and get that diameter for you - also, may make a picture of the model as it sits right now.

Hank