On the dimensional accuracy of the ESCI/AMT/Italeri "TU-26", or rather lack of it

[Bonehammer]

Hello all,

Some time ago I pulled the ESCI "Tu-22M/Tu-26" (they didn't know which one was correct) out of storage. It is clearly a victim of its time, with glaring inaccuracies and "representative" details, but at the same time it is not a bad kit, with engraved panel lines and a good fit.

So I started enlarging plans only to find out that plans can be inaccurate, too! (The one I was using had oversized wings and the air bleed doors in the wrong place...)

What to do? The Aerofax book has a great overhead picture of an early -M2 parked on a runway paved with the ubiquitous PAG-14 plates. Because the size of these plates is standard at 2000x6000 mm, I now had a life-size ruler...

At first, I drew a reticle matching the PAG-14 in 1/72 scale on a piece of paper, but it was too coarse to be of any use for me.

I scanned the picture, tweaked for perspective, added a grid (1000x1000 in real life) and soon had something like this...

 

 

The next step was making a 1/72 ruler for the model. I drew it on tape and placed it directly onto the model. Given the number of issues, I don't think it is a big deal if the "ruler" is a bit distorted around the nose...

 

 

This allowed me to assess the issues with the kit and decide what I'm going to correct and how.

Happy modelling,

Bone

 

Edited January 15, 2023 by Bonehammer
Dog clicked on "Post"

[Zoran Srb]

If I may… Esci TU-26 is a waste of time. Either build it as it is, and call it a Backfire, or get Trumpeters one.. I’ve built in my days both, and there is no comparison….

[Shorty84]

Unfortunately, this view doesn't show the other big problem of the kit, namely the too high fuselage. The brilliant correction build of @Flankerman seems to be lost in the depths of the internet but he needed to remove a few millimetres of height along the whole fuselage to make it look somewhat acceptable.

 

Honestly, the ESCI kit of the Tu-22M is just bad and OOB only looks like a Backfire by coincidence (if you squint). I would get the Trumpeter kit and use this as a paint mule or something similar. Of course, this is just my personal opinion. Have fun whatever you do.

 

Cheers

Markus

[Bonehammer]

On 1/16/2023 at 2:49 PM, Zoran Srb said:

If I may… Esci TU-26 is a waste of time. Either build it as it is, and call it a Backfire, or get Trumpeters one.. I’ve built in my days both, and there is no comparison….

 

On 1/16/2023 at 9:22 PM, Shorty84 said:

Unfortunately, this view doesn't show the other big problem of the kit, namely the too high fuselage. The brilliant correction build of @Flankerman seems to be lost in the depths of the internet but he needed to remove a few millimetres of height along the whole fuselage to make it look somewhat acceptable.

 

Honestly, the ESCI kit of the Tu-22M is just bad and OOB only looks like a Backfire by coincidence (if you squint). I would get the Trumpeter kit and use this as a paint mule or something similar. Of course, this is just my personal opinion. Have fun whatever you do.

 

Cheers

Markus

 

Thank you for the input. Yeah the fuselage height was going to be dealt with next (you can find @Flankerman's build on the Wayback Machine, but I had it saved on a hard drive for a while). Indeed the ESCI Backfire is no longer viable as a scale representation of the real thing. Playing with it when the Trumpeter is available is more of an intellectual exercise, like playing chess blindfolded or rewriting Shakespeare's works without ever using the letter F. Or, seen from another point of view, "I paid for all the kits, I'm gonna build all the kits"...

Edited January 17, 2023 by Bonehammer

[Zoran Srb]

40 minutes ago, Bonehammer said:

 

 

Thank you for the input. Yeah the fuselage height was going to be dealt with next (you can find @Flankerman's build on the Wayback Machine, but I had it saved on a hard drive for a while). Indeed the ESCI Backfire is no longer viable as a scale representation of the real thing. Playing with it when the Trumpeter is available is more of an intellectual exercise, like playing chess blindfolded or rewriting Shakespeare's works without ever using the letter F. Or, seen from another point of view, "I paid for all the kits, I'm gonna build all the kits"...

Hey, I can respect that, Just from my point of view, time is ever shrinking resource, but if thats a way you like to roll, and its fun for you, GO FORTH!!!

[meindert]

Hi Bone,

 

I tried to correct the old ESCI kit ages ago.

But as some others suggested, it is not worthwhile to correct this ESCi kit as much better kits are now available.

 

Interested in my old improved model?

 

Look at my new website page here:

https://aircraftinplastic.com/models/backfire/backfire.htm

 

Edited January 18, 2023 by meindert

[Rob de Bie]

On 1/15/2023 at 11:24 PM, Bonehammer said:

What to do? The Aerofax book has a great overhead picture of an early -M2 parked on a runway paved with the ubiquitous PAG-14 plates. Because the size of these plates is standard at 2000x6000 mm, I now had a life-size ruler...

At first, I drew a reticle matching the PAG-14 in 1/72 scale on a piece of paper, but it was too coarse to be of any use for me.

I scanned the picture, tweaked for perspective, added a grid (1000x1000 in real life) and soon had something like this...

The next step was making a 1/72 ruler for the model. I drew it on tape and placed it directly onto the model. Given the number of issues, I don't think it is a big deal if the "ruler" is a bit distorted around the nose...

 

Bone, that's a really interesting method! Lately I've been thinking how to draw the outline of a model accurately, and it's not an easy problem.

 

With your method, you need a camera with a long lense, if you want to avoid deformation through perspective. I'll try to explain my point in the drawing below. The circle represents the fuselage (as an example of the part to be measured), the checkers your PAG-14 panels. The projection of the fuselage on the PAG-14 panels is how you measure the fuselage. With a short lens you get a considerable error, and even with a 200 mm lens there still is an error.

 

 

You found a pretty unique photo of the real thing, but you'll never know what lens (or camera distance) was used..

 

Rob

Edited January 22, 2023 by Rob de Bie

[MarkoZG]

16 minutes ago, Rob de Bie said:

 

Bone, that's a really interesting method! Lately I've been thinking how to draw the outline of a model accurately, and it's not an easy problem.

 

With your method, you need a camera with a long lense, if you want to avoid deformation through perspective. I tried to explain my point in the drawing below. The circle represents the fuselage (as an example of the part to be measured), the checkers your PAG-14 panels. The projection of the fuselage on the PAG-14 panels is how you measure the fuselage. With a short lens you get a considerable error, and even with a 200 mm lens there still is an error.

 

 

You found a pretty unique photo of the real thing, but you'll never know what lens (or photo distance) was used..

 

Rob

Great post Rob! Finally someone with common sense and understanding of lenses and photography! Hopefully this will put an end to simple drawing contours over the photos to create allegedly most accurate plans, like one not-to-be-mentioned modeller from far east does and some of the producers fell on his marketing.

[Bonehammer]

Many thanks to all who showed up to discuss the topic!

@meindert your page on the Tu-22M was among my references although I am not so brave as to attempt the number and extent of corrections you made. I'm thinking of building the thing OOB as a tribute to the unsung heroes of Cold War intelligence!

Indeed, once I started to compare the two pictures, things started to go pear-shaped, undoubtedly due to the lens length effect described by @Rob de Bie... basically, when I scaled the two pictures so that the PAG-14 size matched, the plane outlines were way out, and vice versa.

 

 

 

Similar problems were encountered when dealing with the side view, always from the Aerofax publication. 

A fuselage plug surely improves the looks of the model a lot. I'll see about chopping the top - both you Meindert and Rob showed it can be done, but I've got cold feet.

 

Edited January 22, 2023 by Bonehammer

[Bozothenutter]

Yup, unless you know the lens used (preferably the exact make and model, so you can enter it into the correction tool) you're doomed.

I use F360 to measure stuff from drawings/blueprints, (load picture, draw line, measure line)even then you notice stuff like distortion from scanning etc.

[Rob de Bie]

11 hours ago, Bonehammer said:

Indeed, once I started to compare the two pictures, things started to go pear-shaped, undoubtedly due to the lens length effect described by @Rob de Bie... basically, when I scaled the two pictures so that the PAG-14 size matched, the plane outlines were way out, and vice versa.

 

You can still learn quite a lot from your analysis, like the wing sweep angle. and the the shape of horizontal tails. So don't stop trying! I use your method too from time to time. 

 

Here's a variant: I photographed the model from far away (4 meters or so), drew its outline, and projected that on a photo that was made with a short lens. I knew the wheelbase of the real thing, and that allowed me to scale both the drawing and the photo, and then overlay them. It soon became clear why the model looked so strange, the wheelbase was completely wrong.

 

 

Rob

[Rob de Bie]

11 hours ago, Bonehammer said:

Similar problems were encountered when dealing with the side view, always from the Aerofax publication. 

A fuselage plug surely improves the looks of the model a lot. I'll see about chopping the top - both you Meindert and Rob showed it can be done, but I've got cold feet.

 

I did heavy surgery on two WarPac models: the old(er) Dragon/Italeri 1/72 Su-24, and the Hasegawa 1/72 MiG-23.

 

The Su-24 was lowered 1-2 mm along its length (you can vaguely see the cut line on the center+rear fuselage) and shorthened 4 mm behind the cockpit. I based my modifications on a drawing, but that's a risky thing too, since there is hardly any way of checking whether a drawing is correct.

 

 

Here are some modifications of the MIG-23. I'm doing that as training to 'see' and correct shapes. I added a 4 mm plug between the center fuselage and the cockpit, lowered the cockpit section, and removed the spine that was too high. The vertical tail was enlarged too. The modifications were interesting challenges!

 

 

 

Rob

 

[Rob de Bie]

11 hours ago, Bonehammer said:

 

This is another 'dangerous' photo: from the converging tar lines of the ramp, you can see it was made with a rather short lens.

 

A friend made a piece of software, that projects a wire model on a photo. You have 7 parameters to play with, so it's a hell of a job to make the two fit. Plus, of course,  you have to make a 3D wire model of the subject. One very important lesson learned was how strong the effect of perspective is (controled here by 'd', distance). I'm often very amazed how short the lenses were, even in air to air photography. Without the deformation caused by perspective, the wire models will never ever fit on the photo. It was an important lesson regarding the use of photos for measurements..

 

 

Rob

[Massimo Tessitori]

I remember to have been shocked, a lot of years ago, when I first saw a frontal photo of a Tu-22M  and saw how sections were different from the Esci kit in the cockpit and air intakes area. 

[Bonehammer]

On 1/23/2023 at 9:09 PM, Massimo Tessitori said:

I remember to have been shocked, a lot of years ago, when I first saw a frontal photo of a Tu-22M  and saw how sections were different from the Esci kit in the cockpit and air intakes area. 

Agreed, even though the M2 suffers from less issues than the M3, the cross sections are pure guesswork on the mold maker's part...

[Bonehammer]

Behold! Bone is bitten by the Backfire Bug and bites the bullet!

These two days I've been in a "here goes nothing" mindset and I've started cutting plastic. I don't know how far I'll get.

 

 

 

I need to figure out how to get to this stage with a single cut...

 

 

 

 

So this was the state of things at dinnertime tonight.

 

 

I still have to figure out if/how to carry out the rest of the modifications. As Massimo pointed out, the cross sections are all over the place and the kit lacks the long "bulges" on the side for the intake trunking but I'm not losing sleep over it.

 

[Jamie @ Sovereign Hobbies]

I have to say this build makes no objective sense whatsoever, but I love what I see  

[Rob de Bie]

I love it too - go for it!

 

Rob

[Zoran Srb]

I see, you decided to bite the bullet... Well, good luck! In case you change your mind... 

https://www.britmodeller.com/forums/index.php?/topic/235121137-trumpeter-172-tu-26-backfire/

 

 

[Bonehammer]

I haven't given up yet. But I waited a while to be sure that the pieces were thoroughly welded together.

I had cut the intake ramps, so I used those parts to reinforce the fuselage sides.

Because the cuts I made to the sides are rather rough, I used the kit's original joint line glueing the two upper and lower halves together (there is some warping, hopefully I can fix it in a jig when I put everything back together)

 

 

I'm not the best judge of shapes but the wasp waist after the radome looked a bit exaggerated and Blinder-y to me. Tucked out:

 

 

 

 

(The nosewheel well is almost in the right place, needs shortening 5mm, so I'll close the forward part)

 

Correcting the wing glove (the shape is provisional) and getting rid of two awful panel lines:

 

 

Reinforcing the fuselage plug:

 

 

This little piggy stayed home:

 

 

This little piggy went to the slaughter:

 

 

This little piggy is nearly finished and shows the difference from the original part.

 

 

I could have just cut the sides but it might have caused problems due to the thickness of the parts in the center area.

 

I made the plugs from thick plastic card backing sheet from a MPM vacuform), scored to bend. Except it didn't bend. So I glued them leaving a bit of a step, and I'll skin everything with thinner plastic after the correct approximate dimensions are established. You can see one of the candidate donors for the grafts - a pot of sour cream.

 

 

This part scared me, but the first half - cutting - was carried out with minimal fuss. We'll see about putting it back, because the ESCI kit has some Coke bottle shape in this area. The wing swing mechanism is clearly a goner.

 

 

Edited June 10, 2023 by Bonehammer
left out a sentence

[Bonehammer]

This thread probably belongs in Work in Progress by now... anyway, in today's installmente I'm faced with a conundrum.

In the picture below, the two extreme signs mark the correct position of the wing in relation to the fuselage. The mark in the middle is where the main undercarriage leg ought to be. As you can see, it's a bit too aft as it is, if I move the wing aft, it's going to get worse. So the wing repositioning is put on the back burner for now.

 

 

 

So I moved to the cockpit area. The kit provides a cabin that wouldn't look out of place in a DC-3, with comfy recliners, steering wheels sticking out of the instrument panel and plenty of space for standing up and walking around. We know by now that the real thing is very different... so even if the canopy is staying buttoned, I'm doing some improvement to the pilots' station. (The back office stays like it is as it won't be seen).

In the picture below, the kit seats have had their headrest and sides removed, side and central console added, new instrument panel and coaming built from plastic card, holes drilled on the cockpit floor for the control columns:

 

 

Last thing today was taking care of some nonexistant, or ridiculous, panel lines here and there. Because I don't trust the putty to fill the deep panel lines in a go, I cement stretched sprue inside them, then fill and sand smooth. You may have seen some stretched sprue already in place in the previous installments.

 

[Alan P]

Fantastic project with the pointless, dogged determination of a Victorian (era not state) engineering proposal 😅

 

Is there more to come?

[Bonehammer]

On 6/15/2023 at 8:49 AM, Alan P said:

Is there more to come?

Not yet, but not for lack of trying. I'm being distracted with multiple projects, online gaming, and RL, and my main obstacle now is turning the ESCI recliners into a pair of believable ejection seats. Yesterday's attempt was particularly dismal... 

[Alan P]

9 hours ago, Bonehammer said:

I'm being distracted with multiple projects, online gaming, and RL

Honestly, I get it 😩 hope to see more soon.

[ReccePhreak]

I have one of these kits in my stash, acquiring it about 20+ years ago in a trade.

Since then, my "build themes" have changed, and this kit doesn't fit in either of of my 2 aircraft themes. I have been unable to sell or trade it, so I have decided to go ahead and add it to my build queue, with a suitable backstory to fit the Royal Thai Air Force markings I plan to do it in. 

That way, I only have to please myself, and just HAVE FUN with the build. Of course I will be sure all seams are filled, it's painted in a "proper" RTAF or RTN paint scheme, and add some "cool" weapons on it. No stress, just a fun What If build. 

Larry