East Front - Expansion

[Guest Mike]

The modifications are true - but the Tiffy had an 18% chord thickness too - that is it's wing thickness was 18% of the distance from front of the wing to the back - that's a VERY high ratio, makes for a very thick wing, and a low critical mach number.

The speed of sound is 760mph at ISA (15 deg C, 1031 mb pressure) and decreases with density as you say. 400 mph in level flight is mach .52 - and the Tiffy could do that in level flight. I don't know what the speed of the air over the top of the wing was, but it would have been substantially higher than 400mph. Mach .67 is about 510 mph at ISA - remember that's the speed of the air over the top of the wing, not the airspeed of the a/c.

The "tuck" you mention can also be aerodynamic loading due to poor design for the trans-sonic region - the shockwaves completely upset the centre of lift so all the centre of gravity calculations are screwed up!!

Another effect of high mach numbers is vibration - and it was this that broke up the tail structures of Typhoons. Initially the problem was somwhat different - the wing was set close to teh proellor for CofG reasons and the vibration off the prop was what caused the wing to disintigrate ion the test flight you mention (I didn't realise that until today)

[Zanadu]

Yes, I was told that there was a harmonic vibration at diving speed that induced fatigue in the structure.

No, the Vcr (critial velocity) of the a/c is the speed at which the a/c begins to generate shockwaves. The air moving around the wing/airframe has to reach Mach itself to generate shock. The P47 had a wing nearly as thick as the Tiffy, and the P47M could hit 480mph in level flight without compressibility.

At higher altitudes, the a/c would move faster due to reduced drag from thinner air. As the a/c dived downward, its Vt (terminal velocity) went down, while the Vcr went up, all due to increasing air density.

The P38 was the first a/c to encounter it seriously due to the combination of a relatively low Vcr (due to its unusual design), and high acceleration. At 35K, its top speed in level flight was only 30-40 mph below Vcr. Going into a dive from 35K it would be well into compressibility by the time it reached 28-29K, but it the pilot didn't panic, he could still recover when the a/c hit denser air at about 10K (plus or minus about 1K) and Vcr increased and Vt went down.

Result was that compressibiltiy in WW2 a/c occured when an a/c dived from high altitude.

[Zanadu]

Oh, and it wasn't the wing that was damaged on the test flight, it was the fuselage skin behind the cockpit, and the framing structure under it.

[Guest Mike]

Yeah my mistake - the damage was CAUSED by buffetting from the very thick wing root.

You may be interested in http://naca.larc.nasa.gov/digidoc/report/wr/78/NACA-WR-L-78.PDF - a wartime document that give Mcr for a P47C as mach 0.64.

I doubt the P47 had anything liek the chord ratio of hte Typhoon - it's root chord was 110 inches, and a 17% ratio would have required a thickness of over 18 inches.

The only source I've found oin teh web tat gives a thickess is this Greek (?) hobby page which lists it as 14.3%, or about 1/7th rather than 1/6th - it might not sound a lot, but it is - the Spitfire had about 13% at the wing root and 6% at the tip and as considered a thin wing, the Tempest had a "laminar flow" wing with a ratio of a "mere" 14.5%.

The Tiffy wing was THICK.

[bartbert]

LA-5

Real World Data

Name: La-5

Manufacturer: Polikarpov

Type: Fighter

Number of Engines: 1

Horsepower: 1,850 hp

Max Weight: 7,198 lbs.

Max Speed: 403 mph

Number of Guns: 2

Crew: 1

Year Introduced: 1942

The La-5 was a redesigned aircraft from the LaGG-1 by designers Lavochkin, Gorbunov and Goudkov. The LaG-3’s name took into account the removal of one of the members of the design team and finally the La-5 was created almost entirely by Lavochkin alone.

The La-5 was a wonderful improvement. Pilots declared it superior to the Yak-7. It had an excellent roll rate, its speeds were comparable with German fighters and it could complete a full circle in less than 19 seconds.

On the down side, the plane could only stay in the air for 40 minutes at a time. Also, there was a separate control lever for the throttle, the mixture, propeller pitch, radiator, cowl flaps, and the supercharger gearbox which tended to distract the pilot while he was trying to conduct a battle. In fact, just to create a rapid acceleration involved six different levers. The German aircraft used only one automatic engine control lever to get this same effect.

[bartbert]

J7W1 Shinden

Real World Data

Name: J7W1 Shinden

Manufacturer: Kyushu Hikoki

Type: Fighter

Number of Engines: 1

Horsepower: 2,130 hp

Max Weight: 10,841 lbs.

Max Speed: 469 mph

Number of Guns: 4

Crew: 1

Year Introduced: 1945

The J7W1 "Shinden" which is Japanese for Magnificent Lightning was the first plane to go into any stage of production with a canard configuration. A canard configuration means the wings were mounted at or near the rear of the aircraft. This configuration is used on some of today’s newer fighter planes.

The "brainchild" of Captain Masaoki Tsuruno, the Shinden was also one of the strangest looking aircraft to be dreamed up in WWII by not only looking like a goose, but strange that the engineers mounted the engine backwards inside the rear half of the fuselage. The radial, air-cooled power plant drove a 6-blade, pusher propeller on the end of an extended drive shaft. With the propeller fitted at the tail, it was necessary to use a tricycle landing gear consisting of one wheel and strut mounted under the nose and two under the wings.

Compounding its unusual makeup, the Shinden was also ordered into production before even its first test flight. At this stage of the war the Japanese had little choice as the Allies were pounding their cities with air raids on a regular basis. Captian Tsuruno made its first test flight on August 3, 1945. He flew two more times on the 6th and the 9th, but before he could fly his 4th time, the war ended.

There were two prototypes made and there were plans for a turbo-jet version when war was halted. The US Navy dismantled and sent the second prototype home for testing but is not believed to have been test flown. In 1960 it was sent for display at the National Air and Space Museum, Smithsonian Institute.

[Guest Mike]

Brian the pictures aren't showing

[bartbert]

Hmmm. I've tried it from two different computers and the pictures are showing just fine for me.

[stoat]

I can see them as well.

[Guest Mike]

It must just hate me then - I get the little red "X"'s no matter what I try.

But I've seen them before!

[Guest Mike]

For those uf us who can't see the pics - here's a short video of Soviet a/c from WW2 - black and white, whith a fairly melancholy sound track, and pretty tame by western standards, but scene setting none-the-less

http://video.google.com/videoplay?docid=-778658388037680082&pl=true

[Sixxkiller]

SWEET, I am actually getting closer to being able to put the real East Front page up on my site as Brian and Dan are now leaking information. You guys are going to be really happy with this AWESOME EXPANSION PACK!!!

The J7W1 is such a beautiful plane. Its not a secret anymore but the best part of the expansion is right here IMHO, 2 new Japanese planes that are comparable to some of the Allied machines.

-Ray

[Fred19]

And what about the ME 262?

[Guest Mike]

What about it?

[Dan Verssen]

Yes, the Me-262 will be included in the expansion!

This will be the first of the Jet aircraft to make an appearance in the game.

[bartbert]

Me-262A-1 Schwalbe

Real World Data

Name: Me-262A-1

Manufacturer: Messerschmitt AG

Type: Fighter

Number of Engines: 2

Horsepower: 1,980 turbojet

Weight Max: 15,550 lbs.

Max Speed: 540 mph

Number of Guns: 4

Crew: 1

Year Introduced: 1944

The second jet fighter of the war (the British Meteor I was deployed first), it was first flown in July of 1942. Hitler did not make a decision on the jet until November 1943, and only as a bomber. However the development team built both a fighter and bomber version under some subterfuge and risk to themselves.

The fastest plane in WWII, it suffered from engine fires, breakups, and the 30mm guns were prone to jam. Also, the landing gear had a tendency to collapse on landing. Still, 1,433 were built, and accounted for over 100 Allied bomber and fighter kills. However, a lack of fuel kept most of the "Swallows" grounded.

[bartbert]

P.11C

Real World Data

Name: P.11C

Manufacturer: PZL (Panstwowe Zaklady Lotnicze)

Type: Fighter

Number of Engines: 1

Horsepower: 600 hp

Max Weight: 3,638 lbs.

Max Speed: 233 mph

Number of Guns: 2

Crew: 1

Year Introduced: 1934

The P.11c was one of the very first metal covered aircraft. Designed when most others were still wood and canvas biplanes, this craft also used a redesigned wing that dipped in the middle to give its pilot better visibility. They were also advantaged with a very durable construction that could take off from rough, short fields easily.

Unfortunately, it was quickly made obsolete as other countries brought out their metal designs. Most P.11c aircraft were equipped with only 2 machineguns and only a few had a radio.

The P.11c is remembered as the first aircraft shot down in all of World War II. On the upside, it also happened to be the plane type to claim the first Allied victory by shooting down two Do 17Es. It was also the first airplane to successfully ram an enemy plane during WWII.

[lakespeed]

Ugh, you guys are killing me here....and I think we're getting rid of the internet for the summer, too.

[Guest Mike]

Brian's giving away too many secrets!!

The 262 is a pretty dangerous opponent, but has its limitations too. I think most ppl will be well satisfied with the new features it brings to the game.

But I actually prefer the lower tech a/c and the P-11 is another fun machine to use.

Even if I still can't see the pics!

[Guest Mike]

Originally posted by bartbert:

The LaG-3’s name took into account the removal of one of the members of the design team

I've never read this before - I know Gorbunov and Goudkov left the design team one at a time, but they were still around when the I-301 was designated the LaGG-3 AFAIK, and it is always referred to as the LaGG-3 in all the literature I have seen.

Do you have a source?

On a side note I think a bibliography of sources woudl be a useful addition to the game's documentation too!

[Guest Mike]

Found another good site for early/mid war Soviet stuff - mainly the monoplane fighters Yak, Mig & LaGG/La series.

VVS Research site

[Dan Verssen]

Here's the source...

http://en.wikipedia.org/wiki/Lavochkin_La-5

[Guest Mike]

I think you mis-read it - the Wiki article has the LaG-5 for a short period of time, not the LaG-3.

Not that I've ever heard of that either mind you...I think someone may have gotten this one wrong

Gudkhov worked on a radial powered derivative of the LaGG-3 using the same M82 engine as the La-5, but completely seperately from Lavochkin - Gudkhov was in Moscow, Lavochkin was at Tblisi working with Engineer Valedensky from Shevtsov's design bureau - who had designed the M82.

2 prototypes of Gudkhov's design were built at Moscow, but only 1 completed by hte time the factory had to be hurriedly evacuated in 1941. The a/c was designated LaGG-3/M82, or Gu-82.

Subsequently Lavochkin's version flew 3 months before the Gu-82 could be rebuilt and test flown, and it was Lavochkin's design that went into production.

This is from "Soviert Airforce Fighters" by Green & Swanborough - I may have to go edit the wiki article!

[Zanadu]

My source: William Green's WARPLANES OF THE SECOND WORLD WAR (Vol. 3) States that the early LaG-5s were built by re-engining LaGG-3 airframes, and adds: "but at an early stage in the production programme the boosted M-82F was installed, the rear fuselage was cut down, an all-round-vision cockpit canopy provided, and the designation changed to La-5."

[Guest Mike]

That's the same Green as was co-author of the book I quoted

When was Warpalnes published? Russian fighters dates back to the 70's or early 80's IIRC (dont' have them here at work) so he may well have updated info since then?