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Valom B-26 vs Hasegawa B-26 - what is going on here?


WV908

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Hi all, as the title suggests, I have a copy of the 1/72 Hasegawa B-26B/C and a copy of the 1/72 Valom B-26B (Early) with the short wings. 

 

Now, knowing the Valom kit has the shorter tail, I lined up the fuselages and found myself to be very disappointed as none of the panel lines, major shape changes or cut-outs actually match up. The nose is also significantly shorter on the Valom kit, but looks longer when you line up the payload bays, as in my photo;

 

IMG_20200607_211651

 

So either the B-26B (Early) and the B-26B/C had vastly different fuselages or one of the manufactures make a massive mistake. Would anyone be able to help me on this please? 

 

Cheers, 

  WV908 

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1 minute ago, Graham Boak said:

Valom made the error.  or errors.  Who knows how?

Oh dear :( 

 

Looking at it I have three separate cuts to make to add fuselage plugs.

 

Cheers,

  WV908

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Not so much in length, but it is too fat and hence too deep.  Far better to get a replacement fuselage from some older kit of the aircraft, if you can, and save what you can elsewhere.  However, I'm not sure how the fatter fuselage will have affected the overall span, but am deeply suspicious.  This is one I saw a review of early enough to avoid.

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I find it strange how such errors can be made, even in the short run business and especially where Valom had both the Airfix and Hasegawa kits available as references to copy from.

 

Cheers,

  WV908

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The longer I look at it, the worse it gets.

 

The fuselage profiles do match in both top and bottom outlines, it's just that nothing between them does and you can't line them up at the same time due to the fat fuselage. It's not just too fat, but it you try and take a sectional view anywhere and compare it to the Hasegawa it's miles off. 

 

I'm fairly shocked at just how bad the fuselage is on this kit. The shape around the canopy baffles me.

 

Cheers,

  WV908

Edited by WV908
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19 minutes ago, Graham Boak said:

No, the upper surface is more curved than the lower.  Maybe a bit exaggerated with a pretty thick section, but right as far as the camber goes, in principle.

I think you'll find the opposite is the case on the actual aircraft. The upper curve is not as exaggerated as that & the incidence is too flat. How Hasegawa has it, looks about right. If the Marauder had a wing profile like that Valom interpretation it would never take off no matter how long the runway was!

The Hasegawa design is nearer the mark.

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On the real aircraft, any real aircraft except those rare few with zero camber wings, the upper surface of the wing is more curved than the lower.  This is what provides lift at zero angle of attack.   (Very basic aerodynamics.) The Valom wing/body incidence does indeed look too flat, but the camber is the right way around, if not matching that of the actual section.   Agreed that the Hasegawa looks better.

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There was a good article reviewing the Valoom b-26 illustrating its errors. Couldn't find it. The Hasegawa kit is reckoned to be the best. For an earlier short wing/tail B-26, the Monogram Snap-tite kit is considered to be the most accurate. There are small differences in the fuselage shapes between the Hasegawa and Monogram kits. What is lacking is the sharply angled tail gunner's position for the Monogram kit. 

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2 hours ago, Gmat said:

There was a good article reviewing the Valoom b-26 

I think you are right. I think this is it but pics have gone.

https://www.tapatalk.com/groups/hyperscale/valom-1-72-b-26-evaluation-pic-intensive-t130267.html

There are several other reviews which do not pick this up.

I think the Valom one was based on inaccurate drawings from Detail & Scale book.

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1 hour ago, Ed Russell said:

I think the Valom one was based on inaccurate drawings from Detail & Scale book.

Yep- they blew it, big time! The old Monogram snap-tite kit is very accurate for an early short wing short tail Marauder, with the manual  twin .50cal tail gun position. If you are wanting an accurate early Marauder, you should look for the Monogram kit at a trade table or auction site and use the detail parts out of the Valom/Airfix kit that will fit. The transparencies on the Monogram kit have tabs for snap fitting, but vacuform replacements are available. Biggest hurdles will be making an accurate cockpit and wheel bays. The Monogram kit does have very nice mainwheels, props, and early cowlings without the large dust filter intakes. The engines are molded with the cowlings, but are pretty nice. See the links below to the box art and what can be done with the Monogram kit, as well as a collection of period photos. The early single .50cal tail gun position will have to be scratchbuilt, but as you can see in the build article, not really that hard. Marauders had three different tail gun positions:

  • single .50cal manually operated tail gun behind clamshell plexiglass window panels that slid down into the fuselage
  • twin .50cal manually operated tail gun covered by a plexiglass blister
  • twin .50cal Bell  power operated tail gun turret  with the gunner covered by a plexiglass canopy; late production aircraft had a spent case/link pannier under the rear fuselage.

 

https://www.scalemates.com/kits/monogram-1101-martin-b-26-marauder--1242128

 

https://www.aircraftresourcecenter.com/Gal13/12801-12900/gal12886-B-26-Dedig/00.shtm

 

https://modelingmadness.com/scott/allies/us/b26b.htm

 

https://www.worldwarphotos.info/gallery/usa/aircrafts-2-3/b-26-marauder/

 

If you decide to do a B-26 with the single .50cal tail gun, see the link below for description, factory diagrams, and photos of period and restored Marauders with the single gun position.

https://www.tapatalk.com/groups/hyperscale/early-b-26-marauder-tail-gun-position-any-referenc-t513987.html

 

Hope this helps!

Mike

 

Edited by 72modeler
added text, added links
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4 hours ago, Gmat said:

There was a good article reviewing the Valoom b-26 illustrating its errors. Couldn't find it. The Hasegawa kit is reckoned to be the best. For an earlier short wing/tail B-26, the Monogram Snap-tite kit is considered to be the most accurate. There are small differences in the fuselage shapes between the Hasegawa and Monogram kits. What is lacking is the sharply angled tail gunner's position for the Monogram kit. 

Scale Aviation Modeller 2008 08 V14 #8

Scale Aircraft Modelling 200902

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15 hours ago, Lightningboy2000 said:

I think you'll find the opposite is the case on the actual aircraft. The upper curve is not as exaggerated as that & the incidence is too flat. How Hasegawa has it, looks about right. If the Marauder had a wing profile like that Valom interpretation it would never take off no matter how long the runway was!

The Hasegawa design is nearer the mark.

Bear in mind that the one of main differences between the two marks of B-26 was, in fact, a massive increase in the wing's angle of incidence.

(edit, not within the B block)

 

As for the airfoil,: Valom has it wrong in this instance. The B-26 used a symmetrical airfoil at the root of the wing, specifically NACA 0017.

 

(The first two digits of a four-digit NACA airfoil designate camber in degrees (zero) and position of the max camber point, front to back along the chord, as a percentage divided by 10. WIth a zero camber airfoil this is also necessarily zero. The last two digits are section thickness in percentage: 17 per cent here. )

 

Zero-cambered, (i.e. symmetrical top/bottom) airfoils do work even though lots of people seem to assume that all aircraft must have camber to fly.  All serious aerobatic types have them, and while they are rare on aircraft optimised for the cruise there are other examples including, surprisingly the B-17 and the Canberra (which of course Martin also built, but under licence).  The P-39 and P-63 also had uncambered wings, incidentally.

 

Canberra apart, the B-26 is the only Martin production type I can find with a zero-camber wing (it tapers out to 0010 at the tip), though the proposed XB-27 also had a zero-camber airfoil pencilled in.

 

 

Edited by Work In Progress
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Here are a couple of photos comparing the Valom and Monogram kits. They may be from the Hyperscale article cited above. If I ever build one of my two kits it will be, based on what I have read, the Snap-Tite, maybe with Valom additions, but I would have to find a decent set of plans first.

 

49983364173_f831344d13_b.jpg

 

49983884466_a56908ea14_b.jpg

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Hi @Ed Russell 

 

Thanks for the comparisons. Have you lined up the fuselages going on wing centre sections as I have in my photo? If so the Monogram and Hasegawa fuselages look to be pretty much the same in shape and length.

 

Thanks,

  WV908

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36 minutes ago, Work In Progress said:

Bear in mind that the one of main differences between the two marks of B-26 was, in fact, a massive increase in the wing's angle of incidence.

 

But I thought we were just comparing the B-26B kits here?  The 3.5 degrees of incidence increase came on the B-26F and it's clear in that photo that Valom have got almost zero incidence on their wing and the leading edge of the wing should be above the window just forward of it.

 

Like has been pointed out also that airfoil section is completely fictional which is obvious from a quick look at a picture. It's like Valom or who ever did the drawing, new that the top of the wing got close to that panel line so instead of increasing the incidence to the correct value they just made the airfoil fatter.

 

yk05y1w8f8x31.jpg

 

 

 

 

 

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19 minutes ago, Tbolt said:

But I thought we were just comparing the B-26B kits here?  The 3.5 degrees of incidence increase came on the B-26F

Yes, fair point, I'd mentally associated it as happening within the B block alongside the longer span wing and other changes

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1 hour ago, WV908 said:

Have you lined up the fuselages going on wing centre sections

As I said, these pictures are not mine.. I would have to go and find my B-26 models to do that - and it's freezing cold out there (2C at the moment!)

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13 hours ago, Graham Boak said:

On the real aircraft, any real aircraft except those rare few with zero camber wings, the upper surface of the wing is more curved than the lower.  This is what provides lift at zero angle of attack.   (Very basic aerodynamics.) The Valom wing/body incidence does indeed look too flat, but the camber is the right way around, if not matching that of the actual section.   Agreed that the Hasegawa looks better.

I don't know about the B-26, but I read that the B-17 used NACA 0015 and 0018 airfoils which are both symmetrical.

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8 minutes ago, Work In Progress said:

In post #17 above perhaps ? 😆

No because you didn't quote the B-17 airfoil versions and I didn't refresh the page after you added that to your post 😀

 

Anyway since you said it was a 0017 on the B-26, this shows that Hasegawa isn't that far away and Valom is a long way off.

 

http://airfoiltools.com/airfoil/naca4digit?MNaca4DigitForm[camber]=0&MNaca4DigitForm[position]=0&MNaca4DigitForm[thick]=17&MNaca4DigitForm[numPoints]=81&MNaca4DigitForm[cosSpace]=0&MNaca4DigitForm[cosSpace]=1&MNaca4DigitForm[closeTe]=0&yt0=Plot

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