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The wings of late Il-4s
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Author Topic: The wings of late Il-4s  (Read 13585 times)
Massimo Tessitori
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« on: June 05, 2012, 02:23:05 PM »

Hi,
I am in doubt about an apparent discrepancy between texts and photos of Il-4s built after 1943.

According to many textual sources, it looks that the wing was modified in late 1942/43. For example, see
http://www.airwar.ru/enc/bww2/il4.html
A plane with wooden and thicker wings with a swept platform, containing additional tanks, increased flaps area and reinforcements on the lower surface, was tested in october 1942, followed by at least 10 similar production planes. It looks that, although heavier, its flight characteristics were better because the cg has moved backward with the modifications made in 1941/early 1942, as it was for the Il-2, and the increase in range was good.
The planes with wooden wings were more vulnerable to enemy fire, so they weren't accepted for mass production.
At this point, one should deduct that a thicker metal wing with additional tanks and swept platform and increased flaps area had taken the place of the earlier one, but the textual sources are unclear on this. Some affirm this, as Gordon, some speak only about increasing of flaps and wing thickness, larger wheels and new props,  as Stapfer on 'In action'.
The photos of the prototype with wooden wing show clearly that it had the inner aileron section deleted to increase the flaps, but all photos of late Il-4s I have show the usual ailerons in three sections, apparently as the planes of 1941.
I think that the authors of the books themselves don't know this. In the good monograph of Kotelnikov, there is a 5 views drawing of the prototype with wooden arrow wings aside many earlier variants, but no any drawing of the late standard Il-4 with metal wings.
I had a look to the photos of the plane in Monino, but it shows some strange characteristics, as the flat wingtips and asymmetrical panelling, probably due to the fact that it was rebuilt from a wreck. Besides it results built before the modification of the wings.
Any ideas?
Regards
Massimo
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John Thompson
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« Reply #1 on: June 05, 2012, 05:11:52 PM »

Hi Massimo! Are any of these helpful?
http://www.wunderwaffe.narod.ru/Magazine/AirWar/112/Draw/index.htm
http://www.airwar.ru/other/draw/il4.html
http://www.airwar.ru/other/draw/il4aik.html
http://www.airwar.ru/other/draw2/il4-3.html

Also two pages of text which can be translated with Google Translate or Babel Fish:
http://www.wunderwaffe.narod.ru/Magazine/AirWar/112/01.htm
http://www.wunderwaffe.narod.ru/Magazine/AirWar/112/02.htm

Photos:
http://www.wunderwaffe.narod.ru/Magazine/AirWar/112/Pictures/page_01.htm

John
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Massimo Tessitori
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« Reply #2 on: June 06, 2012, 12:29:04 AM »

Hi John,
thank you for the links. The first one is interesting because it shows both the drawing of the standard wing, bot those of the wooden swept wing.
The other links depict a Russian translation of the Squadron/signal monograph. They have some photos. I can't see differences in wings between early and late Il-4s. Then, apart for the swept wing, what about other differences that they describe as adopted after 1943, as bigger flaps? How were they enlarged, I wonder?
Regards
Massimo
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Psy06
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« Reply #3 on: June 08, 2012, 02:30:19 PM »

Massimo, the more information I learn, the more it seems to me that the IL-4 with an swept-wing was not existing at all, except of course the prototype.

I had the opportunity to look a manual Il-4 of 1943 series production, it describes many interesting things, like wood parts, but wing it have a streamline.

The only good example Il-4 that we have, it is from Poklonnaya Hill Museum.
This plane was produced at factory № 126 (Komsomolsk-on-Amur) at 1945, i.e it is the latest at series production. It have a many features of a late type, differ from 1943 production, like new elevator type, different carburator intakes, different equipment layout and... astreamline wing!
Very strange Smiley

We have another data sorce, a Training Film NII VVS filmed at 1944. It present beautiful example of 1944 series production, it differ from both 1943 and 1945 series, and have a streamline wing!

Where, tell me where Ils with swept wings?!! I have not seen even a single picture of wartime, which could be considered as a swept wing. They just do not existing at all!
« Last Edit: June 08, 2012, 02:43:07 PM by Psy06 » Logged
John Thompson
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« Reply #4 on: June 08, 2012, 04:40:34 PM »

It's good to see you here, Psy! Thank you for joining the discussion!

John
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Massimo Tessitori
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« Reply #5 on: June 08, 2012, 06:41:30 PM »

Hi Psy,
observing both the photos in my archive and the huge documents that you've shown in the topic of Scalemodels.ru, I agree that there is no evidence of arrow-shaped wings except for the plane with wooden wings. I wonder if the other modifications, as the thicker wing with more tanks, were preserved in the straight metal wing. Some difference should be visible in panelling.
I haven't well understood the difference in flaps and ailerons between 1943 and 44 planes, could you show it to me better, please?
Regards
Massimo
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Massimo Tessitori
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« Reply #6 on: June 08, 2012, 07:00:02 PM »

Hmmm... I've observed the image of the plane inflight in the movie on Scalemodels.ru at 09.08. It looks compatible with the wing shape of the experimental arrow-winged Il-4. Have a look, please.

http://www.youtube.com/watch?v=rRLLM4msEko&feature=player_embedded#t=547s
http://www.wunderwaffe.narod.ru/Magazine/AirWar/112/Draw/13a.jpg
Regards
Massimo
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KL
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« Reply #7 on: June 08, 2012, 07:39:10 PM »

Where, tell me where Ils with swept wings?!! I have not seen even a single picture of wartime, which could be considered as a swept wing. They just do not existing at all!

observing both the photos in my archive and the huge documents that you've shown in the topic of Scalemodels.ru, I agree that there is no evidence of arrow-shaped wings

Dmitri/Massimo,
Please refrain from:
No "photographic evidence" = it did not exist!

it's the same as saying: If I haven't seen it, it didn't exist... Sad

Cheers,
KL
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KL
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« Reply #8 on: June 08, 2012, 08:19:55 PM »

Where, tell me where Ils with swept wings?!!

It is true that Il-4 development has been poorly documented in Soviet/Russian literature.  Authors wrote more about prototypes and Il-4 hypotetical operatios than about series planes.
In 1970es, Shavrov (official aviation historian) had just few paragraphs abou Il-4. He didn't even mention swept wings...  But drawings by I. Sultanov show Il-4 withswept back wings.
http://base13.glasnet.ru/text/shavrov2/1-04.htm#1



In 1985 I. Rodionov publishes better drawings in Modelist Konstruktor magazne: http://hobbyport.ru/avia/il_4.htm
Rodionov provides two types of metal wings, IMHO both straight.



In late 1980es, H. Novozhilov (then head of the OKB Ilyushin) creates confusion in his book "Planes of the OKB Ilyushin"

according to Novozhilov, all Il-4s made after mid-1942 had swept back wings
http://eroplany.narod.ru/planes/db-3/db-3-1.htm
http://eroplany.narod.ru/planes/db-3/db-3-2.htm
http://eroplany.narod.ru/planes/db-3/db-3-3.htm



Novozhilov's text was "copied" in many subsequent books; Yegorov, Gordon etc.

HTH,  Smiley
KL
« Last Edit: June 08, 2012, 08:22:42 PM by KL » Logged
learstang
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« Reply #9 on: June 08, 2012, 09:27:07 PM »

Interesting.  Thank you for the links, Konstantin.  And I thought things were a bit muddled for the IL-2.

Regards,

Jason
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Massimo Tessitori
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« Reply #10 on: June 09, 2012, 12:09:27 AM »

Hi Konstantin,
thank you for your links and considerations.
I have noticed that Shavrov's book show a plane with swept wings. Unfortunately the poor details of ailerons leave still doubts, but this is in favour of swept wings.
The drawing of Rodionov show both upper and undersurface of the same straight wing. The undersurface shows the aileron hinge line, while the uppersurface shows rectangular panels corresponding to internal tanks.



I've made an automatic translation of the text of Novozilov,

Quote
Since the autumn of 1941 due to lack of duralumin to serial DB-DF airplanes began to install wooden cabin of the navigator, the cockpit floor and aft fairing. The emergence of a fourth member of the crew and armor shooters significantly shifted the flight back alignment planes, worsened the characteristics of their static longitudinal stability and control. These characteristics have been improved on the production aircraft, which began producing in the summer of 1942 they had a new detachable part of the wing with the "arrow" on the leading edge (Fig. 1.13), move forward flight alignment relative to the mean aerodynamic chord of the wing. Detachable portion of the wing with an arrow also had a new aerodynamic profile, increased to 10% relative thickness and the mixed structure of the metal rails, wooden paneling and ribs. The thicker profile of the detachable wings and removal of the lower rib belts for the cladding of the wing to form a ribbed shell



In Fig. 1.13. Diagram of the IL-4 (wings with "arrow")

allowed to establish in the console instead of a three-sealing fuel tank, increase the mass of fuel at 1135kg compared with conventional serial machines, the DB-DF. Increased weight of the aircraft and flight, his weight began to overload is 12 130 kg. However, the aircraft maintained a sufficiently high aircraft performance data. In normal flight mass 10 055 kg, he had a top speed of 404 km / h at an altitude of 6650 m because of the large supply of fuel has increased considerably the range of aircraft flight. With a normal load of 1,000 kg of bombings on the inside of the suspension range increased to 3585 km at a cruising speed of 340 km / h and up to 4265 km at a cruising speed of 250 km / h Despite the significant increase in mass flight, the aircraft retained the ability to be based on front-line airfields, which provides greater at 2 m 2 area of landing pads and installing a new propeller AB-5F-158 increased diameter. With the new aerodynamic configuration of the wing has improved handling and maneuverability of the aircraft. According to the pilots flying aircraft with a "needle" is made ​​easier. A positive feature of the DB-DF airplanes had the opportunity to perform on them until flight mass 9420 kg of a long flight with one engine running. To reduce the load on the pilot's leg in the air with one engine running chord rudder trim increased by 40%.

the text says that the new wing had a wooden skinning. From other sources, we know that very few planes with wooden skinning (10?) were built because they were more vulnerable. The doubt is if they returned to the metal wing preserving the other modifications, as it sounds reasonable, or not.

At this point, we can continue to look for photos. If the arrow wing was so common, should be recognizable under some perspectives. It could be easier to find it on movies than on photos. It should be understood if there are details (of the ailerons, for example) allowing to distinguish the type of wing from many perspectives where the shape is unrecognizable.


Hi Psy, you are able to made 3D drawings, isnt it? Coudn't you make drawings of both swept-wing and straight-wing Il-4s to try a comparison with photos from the same perspective?

Regards
Massimo
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KL
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« Reply #11 on: June 09, 2012, 12:53:30 AM »

Most complete and detailed description of Il-4 development is in Kotelnikov's Il-4 text published as Aviatsiya i Kosmonavtka mag spec issue in 2005 (and later as Yauza/Eksmo book)


http://vadimvswar.narod.ru/ALL_OUT/AiKOut02/DB-3/DB-3001.htm
wooden wing at:
http://vadimvswar.narod.ru/ALL_OUT/AiKOut02/DB-3/DB-3078.htm
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Psy06
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« Reply #12 on: June 09, 2012, 02:14:15 AM »

In 1985 I. Rodionov publishes better drawings in Modelist Konstruktor magazne: http://hobbyport.ru/avia/il_4.htm
Rodionov provides two types of metal wings, IMHO both straight.

You little wrong, its just top and bottom left wing Smiley bottom part mirrored for layout reasons.

About book of мr. academician Novozilov, I have reasons to doubt the reliability of the information contained in the book. I think that certainly he did not deliberately lie, but some facts seem entirely implausible set out in the form. Look like the book writed not himself, but a lasy student who work for some profit.

Hi Psy, you are able to made 3D drawings, isnt it? Coudn't you make drawings of both swept-wing and straight-wing Il-4s to try a comparison with photos from the same perspective?

I know the movie you ask, but I see here standart stright wing.

Here my story, I am about 2 years engaged in the creation of a new simulator based on the continuation of the "IL-2 Battle of Britain". I already made a hi detailed model of Il-4 mod 1942. And it at some angles and camera control, look like have swept wing. And because it very sceptic about correct photo recognition. I sign some boring copyright papers and because it can't show much, sorry. But, I already try to compare, and as I already says, no swept wing 100% recognition Sad
I.e maybe it present, maybe not.

About a flap, you already have early style flaps at Rodionov drawings, here a photo late:


PS I write some words to Ivan Rodionov himself, maybe hi can say something.
« Last Edit: June 09, 2012, 10:00:10 AM by Psy06 » Logged
Massimo Tessitori
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« Reply #13 on: June 09, 2012, 02:34:35 PM »

Hi Konstantin,
this link is interesting, thank you. I already had the .pdf, put this one allows to use the automatic translator.
It writes so:
Quote
Release of IL-4 in 1943 increased significantly compared with the 42-m. Manufactured aircraft in 1568. Interestingly, the leader in the number of bombers moved built the plant number 39 - 698 cars. 126th gathered 613. ADD took about two-thirds of total production - 1198 IL-4. This made it possible to form eight new regiments. Almost all the remaining received a naval aviation.
 
During the year the construction of the bomber made several important changes. The most significant of these was the so-called "arrow wing" designed in February 1943 had the same idea as before - a little bit to turn the console back. But it made it easier than in 1942 next to the usual ribs, which started from the console, at an angle of 6 ? set a new, additional, which became the butt, slightly lengthened the spars and covered all of this covering. Along the way, changed the design to connect nodes. The event raised longitudinal stability, improved handling qualities more IL-4.
 
Order of the People's Commissariat of Aviation Industry on March 27, 1943 provided for the implementation of all production plants increased sweep consoles, plywood sheathing them, additional fuel tanks, ailerons with fabric wrapped and wind compensation, Dust filter on the suction nozzles and flame arresters. The entire complex would like to learn to May 1943 with the release of each enterprise reference planes. Plant number 23 produced such a machine by mid-June, the plants number 39 and 126 - in July. But in practice, innovations appeared on serial machines, not simultaneously but sequentially.
 
Plant № 126 introduced spike wheel 470x210 mm with a long counter on the 121-series, and the wing of "Arrow" - on the 128th. At the last time there were more and ailerons trimmed cloth instead of dural sheet and enlarged on the chord, and elevators with wind compensation. Since the "arrow" shifted the center of gravity, then the removal of the chassis at the same time reduced to 120 mm.

So, Kotelnikov writes that the arrow wing was selected for production, and gives the starting date too. But it writes that the wing had wooden skinning.

at pag.81 there is the photo of a plane with a crashed wing, whose skinning looks really wooden.
http://vadimvswar.narod.ru/ALL_OUT/AiKOut02/DB-3/DB-3081.htm


On the Il-4 with wooden wings, he writes:
Quote
In 1942, Ilyushin Design Bureau has tried to rectify the situation and longitudinal stability. Back in 1939 after testing one of the first serial DB-3F Institute of the Air Force proposed to shift the back of the cantilever wing, slightly turning them back relative to the point. Designers have responded quickly enough, in February the following year by submitting the necessary drawings. It was supposed to make a prototype of the plant number 39. But when an overloaded plant did not do it.
 
The idea came after two years. At this time, did not stop turning the console, and completely remodeled it. The design of the console has now become mixed. Spars were metal, and the ribs and the casing is made of wood. At the same time using a thicker airfoil and rib taken out of the shelves lining - appeared on the surface of the wing is clearly visible ribs. The internal volume of the wing increased, and the console instead of a single squeezed three fuel tanks, increasing the supply of gasoline at 1135 kg, significantly more than the allowed overhead bins.
 
Manufactured at the plant number 23 aircraft with new consoles finished testing October 23, 1942 This car is also different plates and screws increased area AB-5F-158 instead of the standard VISH-23. Due to the transition to a mixed design, and increased fuel takeoff weight increased to 12,130 kg, which lowered the maximum speed of 404 km / h, but the increased range, which reached 4265 km with a bomb load of 1000 kg. New wing at the same time simplifying the piloting of the machine. IL-4 plant № 126 consoles with wooden screws and the AB-158A-5F passed state tests in September and October 42nd. The tests he passed. New items recommended for implementation in the series.
 
At the end of 1942 on IL-4 introduced a reinforced landing gear wheels on the main rack, and the tail wheel is increased in size (470x210 mm instead of 400x150 mm) with a corresponding change in spike farm. In December, the plant number 23 produced a small series of 10 bombers with the new consoles and reinforced chassis. She was sent to the army trials. Last show at the same time improving the quality of flight a significant reduction in survivability. With the new consoles have released a small number of bombers. Instead, a simple turn of detachable parts of the wing later introduced at different factories.

So, it looks that they didn't reproject the whole consoles, but modified them to turn backwards. I have still to understand where the plywood skinning was put.


Hi Psy,
thank you for the photo. I am very interested to know what Rodionov says.
Your work on the next Il-2 simulator is very interesting. Too bad that you can't show the 3D drawings of the I-4 variants! Perhaps I'll make a quick building of my Revell model to compare it with drawings and photos, but it's not easy to build and I fear to ruin it.

Regards
Massimo






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Massimo Tessitori
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« Reply #14 on: June 13, 2012, 04:42:31 PM »

Hi all,
maybe the third plane of this line could give an idea of an arrow wing.

while this one looks straight

Regards
Massimo
« Last Edit: June 13, 2012, 04:51:37 PM by Massimo Tessitori » Logged
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