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72modeler

Boeing 307, C-75 details

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I have been researching the four Boeing 307's that were bailed back to TWA in 1944 as C-75's. According to written sources I found, they were fitted with wings, engines, and stabilizers from the B-17G. In photos I have found, you can see the B-17G horizontal stabilizers, paddle blade props, engines, cowlings, and wings with the slots for exhausting air from the intercoolers that were fitted to the G's. My question is: since the wings and powerplants from the B-17G were fitted, did these four 307's also have the turbosuperchargers?  I have found no photos of the underside of the aircraft so modified that shows whether or not they were present. I have my doubts that they were, as there don't seem to be any intakes in the leading edge of the wings for the intercoolers or oil coolers in  any of the photos I have seen, and the exhaust does not seem to be that of the B-17G, It would be nice to know, as I wouldn't have to fill the space normally occupied by the superchargers on my donor B-17G kit, but I wanted to ask the assembled experts. What do you think?

Mike 

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Hello Mike

Not and expert on C-75, and probably not showing you anything new, still ... I found this:

https://www.air-and-space.com/Boeing 307 N19903.htm

Scrolling almost all the way down will get you to the photos of four ex-C-75, which clearly show side exhausts on inboard, and bottom of nacelle exhausts on outboard engines. The same can be seen on this photo of F-BELY by Jon Proctor from Wikipedia ...

Boeing_307_Stratoliner,_Airnautic_JP6984

... and even more clearly on the photo on this page, where the aluminum panel, riveted over former turbocharger impeller housing of No.4 engine can be clearly seen. So I agree with you that installation of B-17 turbochargers on ex-C-75 was highly unlikely. Cheers

Jure

 

 

 

 

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Hi

The B17G wings and stabilizers were attached on return to (or rather perhaps close to)  TWA in some 1944, AFAIR. If you look carefully  on photos  of real stuff, which I posted (as gathered in net) on my build progress thread here

 

You will see that all ex-TWA machines C-75 named  after American Indian tribes at time of US insignia without bars (prior to 1943) has "normal" exhaust pipes on sides of engines, not the B17 style turbo charged exhaust below nacles.

However the silver machine (serial shows that it is one of ex-TWA) having stars with bars has perhaps B17G exhaust, having still slots! - so not a complete wing of B17 was applied.  

boe-c75.jpg

Cheers

J-W

 

Edited by JWM

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P.S.

Antother take of the same 42 688 25 reveal old style exhaust pipe on outer side of inner engine

c75-5.jpg

Whereas older photos showed it opposide: outer engines had pipes on outer sides, inner on the most inner side, This machine has also digfferent coolers

Regards

J-W

compare with this:

7204082888_6b5778185f_b.jpg

 

Edited by JWM

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Jure and JWM,

Thanks for the reply and photos; I think it's clear that turbosuperchargers were not fitted, and that the exhaust configuration was altered at different points in time. What's confusing is some photos show the upgraded 307's with the slots in the outer wing panels and some don't; in addition some photos show the intercooler exhaust vents in the upper wings and some don't. I guess I have a lot of work ahead to make four identical oil cooler and carburetor air intakes, inboard and outboard exhaust pipes, and fill in the slots that held the turbos. Hardest part looks like figuring out how to do the slots in the wings so they are uniform and even and open from the upper to the lower wing surface. As Fagin said in Oliver! "I think I  need to think this out again!"

Mike

 

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Mike, I am just doing those four exhaust pipes.... I hope to show ny 307 on RFI very soon...

Here is nice movie:

https://www.youtube.com/watch?v=omZSyCFWejI

 

And some more photos (I do not know if the link will work)

https://www.tumblr.com/search/boeing 307#

http://www.airwar.ru/image/idop/cw1/b307/

 

TW-B307-NX1940-2.jpg

Here is the only one I've seen with both cmplete  B 17 G wings (most likely with turbo ehhaustss) and stabilizers - but still has slots!

https://www.alamy.com/stock-photo-transport-transportation-aviation-passenger-planes-boeing-307-stratoliner-86382180.html

 

Cheers

J-W

 

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JWM,

 

I'm thinking, after looking at the links you shared, that C-75/307's with original wings had slots in the outer wing panels and slotted wing flaps, as evidenced b y the flap actuator fairings on the underside of the flaps; the 3-view drawing in the one link you provided also shows this. I also believe that those aircraft that were upgraded with B-17G engines and wings, retained the original wing outer panels with slots, confirmed by the photos, and also retained the intercooler exhaust slots of the B-17G wings. What I'm wondering, and I will try to find photos of the four that received the upgraded wing to confirm this, did those wings have the split flaps as fitted to all B-17G's or did they have the slotted flaps? If the wings have no flap actuator fairings, then they are split flaps- if the actuator fairings are present, then they are slotted flaps. What do you think? I am sooo confused!

Mike

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6 hours ago, 72modeler said:

did those wings have the split flaps as fitted to all B-17G's or did they have the slotted flaps? If the wings have no flap actuator fairings, then they are split flaps- if the actuator fairings are present, then they are slotted flaps. What do you think? I am sooo confused!

Mike

Mike ,

Those particular French ones (said to be ex-TWA I think), which have tailplane from B-17 apparently have B-17 flaps

101-600x338.jpg

81-600x400.jpg

No fairings seen on this photo. The wheels are also from B-17 G.

 

The same machine (?) yet in TWA colours

312710f6dcd0adb70b9c23fcea2b2254.jpg

https://imgproc.airliners.net/photos/airliners/9/5/0/2045059.jpg?v=v40

The last (in link) is interesting - the tailplane is from B-17G (sonce no teardrop like fairings close to tips) but the exhaust is without tubo, only "reversed" (outer engines hve pipes on inner sides). no oil coolers below cowlings and no air intakes above. So apparently there were at least three configurations of five TWA machines. The PAN-AM ones is another  story. 

There were only 10 of them and really there is a lot of photos available in net, so one can trace all changies in time for them...

Don't give up :)

Cheers

J-W

 

 

 

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AFAIK, they were originally built with the wings and horizontal tails of the non-turbocharged YB-17s.  The lower nacelle is a pointy-tailed  'boat' shape in all four positions, as you can see from the TWA photo above. The inboard nacelles on the B-17G have square rear ends, in addition to the turbochargers. so the wings retained the original lower nacelles after the rebuilds as there were no spares for these.  The only place such nacelles have appeared in 1/72 is on the Rareplanes YB-17 vacform.

Or  you need to scratchbuild them.....

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JWM and Roger,

 

After reading Roger's post, I went looking for more photos, especially those showing the TWA 307's that were fitted with B-17G stabilizers, engines, and wings. I found a link to a TWA color postcard that I have posted below, that shows 42-88625. In the photo you can clearly see the B-17G stabilizers, the B-17G engines and cowlings, with the tapered lower nacelle fairings Roger described, as well as the fact that it has B-17G inner wings, as evidenced by the oil cooler intakes in the leading edge of the wings versus the externally mounted oil coolers as seen in other photos. In addition the inner wings show the fitment of  the split flaps associated with B-17G's, but the outer wing panels are clearly not from a B-17G as they have the slots. Boy, howdy, you're going to have to find photos of the 307 you want to build at the point in time that it had the external features of the one you want to do. As Roseanne Roseanna-Danna liked to say- "It's always sumthin'!" (This project is getting more and more complicated!)

Mike

 

https://www.ebay.com/i/352532082250?chn=ps

 

Edited by 72modeler
fixed link

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I have the same actual post card, on the back it's dated Feb 24 1945. Even in the link, go to the right arrow, it shows the backside of the card. I got the vac form of the 3oh7 and someday hope to build it to.

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On 12/8/2018 at 6:04 AM, JWM said:

 

Here is the only one I've seen with both cmplete  B 17 G wings (most likely with turbo ehhaustss) and stabilizers - but still has slots!

https://www.alamy.com/stock-photo-transport-transportation-aviation-passenger-planes-boeing-307-stratoliner-86382180.html

 

Cheers

J-W

 

Is there something else in that picture besides that gorgeous Light 15?

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9 hours ago, Admiral Puff said:

Is there something else in that picture besides that gorgeous Light 15?

Hm, maybe I've lost the point... The links is to photo of Boeing 307 Stratoliner F-BELX on Le Bourget airport in 1950. 

Regards

J-W

P.S.

I've just posted my Boeing 307 (C-75) on RFI

 

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10 hours ago, Admiral Puff said:

Is there something else in that picture besides that gorgeous Light 15?

You, sir, are a knave!

Mike

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5 hours ago, JWM said:

Hm, maybe I've lost the point... The links is to photo of Boeing 307 Stratoliner F-BELX on Le Bourget airport in 1950. 

Regards

J-W

P.S.

I've just posted my Boeing 307 (C-75) on RFI

 

Joke, Joyce ...

 

I have a huge love of the Citroen Light 15 - "La Reine de la Route" - and for my money you posted a picture of a Light 15 with some Yank aeroplane in the background ...

 

And Mike - guilty as charged! And proud of it!!

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41 minutes ago, Admiral Puff said:

I have a huge love of the Citroen Light 15 - "La Reine de la Route" - and for my money you posted a picture of a Light 15 with some Yank aeroplane in the background ...

 

And Mike - guilty as charged! And proud of it!!

I did not know  the name "light 15" for this Citroen. I knew it under name "BL-15" . My uncle had that one but with smaller trunk - it was the Citroen BL-11 with 2 liter engine. It was when I was a kid (4-12 let say) and I remember this beast very well :) - like it also a lot :).  In 1968 he with my aunt went by this car for the "just married trip" to Paris (from Krakow, in communist time...) . The Citroen was 16 years old those days. And they returned!

Cheers

J-W

 

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BL stood for Berline Legere thus Light Saloon. BL-15 was a 15CV (French fiscal HP) inline six of 2867cc while BL-11 (11CV) was exactly 2/3 of it - 1911cc inline four.

Originally there have been also smaller (pre-WW2) 7CV models with engines ranging from 1303 to 1628cc.

To confuse things still more the French fiscal HP system differed from the British one, so British (Slough-built) "15HP" model (Light Fifteen) featured the 1911cc four.

Thus it was identical to the very car our late uncle and auntie used for the Krakow-Paris-Krakow trip in 1968.

Cheers

Michael

Edited by KRK4m
misprint

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I think that its name depended on the market - out here it seemed always to be known as the Light 15. There are still a few around here, but not as many (on the road, at least) as there used to be. Actually, the last one I saw was on Bornholm in Denmark, when I was over there 18 months ago.

 

So much for our thread drift, now back to our story ...

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