MW-50 Bf 109s Vs Fw 190 A

[FLYBOYJ]

-"He stopped cutting me off after I cut throttle"
-"I commenced to turn inside him after I decreased throttle settings"

I bet dollars to donuts IN A REAL AIRPLANE I'd be up your ass before you banked more than 10 degrees.

Gaston, you're an ARMCHAIR in more ways than one

 

[Jenisch]

Gaston, I have a basic flight theory book for my private pilot course with just 81 pages of content. Since Portuguese is overall longer to write than English, you should find one with even less pages. I strongly recommend you to buy one.

 

[FLYBOYJ]

 

[GregP]

I realize some people used the Lufbery in WWII, but it wasn't anywhere near as prevalent as in WWI.

And I seriously doubt anyone would engage in consecutive 360° horizontal circles for 10 or more turns. If they did, they would never live to be a veteran.

 

[Elmas]

I bet dollars to donuts IN A REAL AIRPLANE I'd be up your ass before you banked more than 10 degrees.

Gaston, you're an ARMCHAIR in more ways than one

A Friend of mine, Ten. Alberto Scano, of wich in this post

http://www.ww2aircraft.net/forum/aircraft-pictures/scuola-caccia-elmas-32016.html

told me an amusing little story about his training.
One Colleague of his was having an instructional session in a Link-Trainer.
The Chief Instructor, from outside, set the instruments in a position that simulated a flat spin and started shouting trough the intercom:

"You are in a flat spin!You are in a flat spin!You are in a flat spin!
Jump! Jump! Jump!"

The student pilot inside opened the canopy in a hurry and.....parachuted himself out of the linkTrainer....

The poor fella had to pay drinks for a whole month at the Officer's Mess......

So I think other people here are parachuting themselves out of their armchairs.........

 

[FLYBOYJ]

A Friend of mine, Ten. Alberto Scano, of wich in this post

http://www.ww2aircraft.net/forum/aircraft-pictures/scuola-caccia-elmas-32016.html

told me an amusing little story about his training.
One Colleague of his was having an instructional session in a Link-Trainer.
The Chief Instructor, from outside, set the instruments in a position that simulated a flat spin and started shouting trough the intercom:

"You are in a flat spin!You are in a flat spin!You are in a flat spin!
Jump! Jump! Jump!"

The student pilot inside opened the canopy in a hurry and.....parachuted himself out of the linkTrainer....

The poor fella had to pay drinks for a whole month at the Officer's Mess......

So I think other people here are parachuting themselves out of their armchairs.........

LOLOLOLOL!!!!!

 

[davparlr]

I realize some people used the Lufbery in WWII, but it wasn't anywhere near as prevalent as in WWI.

And I seriously doubt anyone would engage in consecutive 360° horizontal circles for 10 or more turns. If they did, they would never live to be a veteran.

It was also used in Vietnam by Migs, as bait for non gun armed F-4s, according to wiki. "Dogfights" also mentioned its usage in Vietnam in one episode.

 

[GregP]

The non-gun F-4's had sidewinders. If they worked, they were immune to the Lufbery circle, not have pilots and being very quick. Alas, the "working" missiles in VietNam were in the minority.

 

[FLYBOYJ]

The non-gun F-4's had sidewinders. If they worked, they were immune to the Lufbery circle, not have pilots and being very quick. Alas, the "working" missiles in VietNam were in the minority.

Actually it was the Sparrows that had an issue. The sidewinder had limitations on where and when it would work.

"About 7500 AIM-7D and 25000 AIM-7E missiles were built, and the Sparrow was used heavily in Vietnam by the USAF and the U.S. Navy. The first combat kill was scored on 7 June 1965, when USN F-4B Phantoms shot down 2 MiG-17s. However, the initial combat results were very disappointing. The potentially long range of the AIM-7 could not be used, because unreliable IFF capabilities of the time effectively required visual identification of all targets. Coupled with the high minimum range of the missile of 1500 m (5000 ft) and poor performance against manoeuvering and/or low-flying targets, this led to a kill probability of less than 10%."

Raytheon AIM/RIM-7 Sparrow

 

[GregP]

FlyboyJ, You are, of course, correct. The main issue was that the F-4 had to keep illuminatuing the target after firing so the Semi-active Sparrow would guide. If the F-4 turned away, the missile would be useless. They NEEDED the sidewainder, but had more Sparrows.

Mental fart on my part ...

 

[Gaston]

Gaston:
1. Thrust in pounds does not equal Horsepower.
Dynamic Thrust (lbs) = Power (HP) / (Velocity (knots) * (6076/(3600 * 550)))
By way of example, a Grumman Hellcat at combat was about 12,325 pounds at combat weight. It had 2000 HP, but let's say he was using 1800 HP to stay with your example. The equation above is NOT for static thrust, it is for dynamic thrust. At 174 knots (about 200 mph) the thrust is 3,371 pounds for a thrust to weight ratio of .2735, which is typical for a WWII fighter. You aren't even close. There are other ways to calculate this force within a few percent, but they won't equal the horsepower being used....

Good to know. So for similar leverage loads, a much smaller percentage of the thrust can be used... 3371 lbs is way more like it...

2. I do not know what "80% of it pivoting back compared to the trajectory" even means. It doesn't make sense to me, but I am not dismissing it. Perhaps the words are just not quite right for me to see it. But, the thrust is the thrust. It does not act along the line of wing incidence. Most engine mounts were canted downward several degrees and had several degrees of side thrust compared to the fuselage datum line The wing usually had several degrees of positive incidence.....

Imagine the vertical height of the prop, then put the micro-second initial pivot point at the bottom 20% height... If you increase AoA, the top of the prop by definition moves back compared to the trajectory, but here it does so for a micro second by dipping the CL and pivoting within the prop's face...

After that, pivoting is much more like you think, but the thrust slanting is set up in amplitude for each ° of AoA...

3. The angle of thrust to the angle of attack is NOT the same as the angle of wing incidence due to down and side cant, but is reasonably close. The actual angle of thrust in a propeller fighter is almost always less than the angle of attack due to down thrust built into the engine mount. The component of thrust along the angle of travel is the thrust times the cosine of the angle of attack, and the component that adds to lift is the thrust times the sine of the angle of attack. It is not constant but varies with the angle of attack..

I see no conflict here.

4. The Center of lift does not move unless the airflow goes transonic or supersonic.

In which case I presume it moves back to create Mach tuck?

If it moved forward only under elevator action at lower speeds, how would you know about it? The elevator's downward tail action would in effect conceal the forward movement with something wanted, and the true extent of the CL's forward movement would be further hidden by the resistance of the prop...

Tilting the whole thing at the prop, even for a microsecond, is what makes the CL squeeze forward: It's easy to visualize...

You may think the prop will resist little, just like it resist little a mirror's drag slowing down its whole surface, but that is like lifting a long one-sided barbell straight up: Easy.

Try to induce a tilt while lifting that long barbell with the heavy end off-center, and the longer the handle the worse the effort...

That is exactly what the prop does when AoA increases... And you can test it yourself on the barbells, although the effect on the prop is actually much worse, because on top of the "off-centeredness" of lifting the nose off-center, slower air from turning starts to hit one side of the prop's front, slanting its thrust against your effort to hold it slanted...

5. The pilot cannot feel the thrust in the stick at all. He feels the elevator and aileron out of trim forces only. That's why he needs trim tabs. He feels the rudder out of trim force in the rudder pedals if he keeps the ball centered. If he doesn't, he just slips or skids through the air without feeling it … Unless the slip or skid is enough to induce a spin.

I never said that he did. The now forward position of the CL insures he never feels any effort as soon as the action is initiated... But that doesn't mean things are the same as before action is initiated...

6. A 10,000 pound airplane at 3g needs 30,000 pounds of lift to fly at 3 g, not 54,000. Any added lift from the propeller thrust just decreases the amount of lift the wing needs to produce. 3g – 3g. In Algebra, the "=" sign means EQUALS. 30,000 pounds does not equal 54,000 pounds … it equals 30,000 pounds. The real only "extra lift" needed is to counteract the tail downforce. So the 30,000 pounds turns into a bit more in a conventional wing-first aircraft and bit less in a canard aircraft (because the forward tail lifts upward instead of downward) but not an extra 24,000 pounds.

You would know that if you knew how much the wings actually bend in flight, but you don't. Hence my inquiry about methods to find that out with strain gages, full scale in case the effect is not scaleable, and matched to static values with wings bent on the ground to evaluate the extent of the actual bending in flight... All of which we now seem to agree was never done on WWII fighters (except for the static on-the-ground part).

7. There is no void created above the wing; the center of lift doesn't shift since the local airflow is not either transonic or supersonic.

I agree this would seem unlikely to persist for more than a micro-second, but then nobody realizes these nose-pulled types might begin to pivot at the nose (not the same as pivoting within the wing's chord), and the effect might be observable only in turning flight with assymetrical incoming air...

8. Your theories are so far off from the aerodynamic formulas that produced the actual aircraft as to be out of the ballpark ... they're craptacular, to quote Bart Simpson. Gaston, the WWII fighters FLEW AS DESIGNED, meaning the designers knew what they were doing and their formulas were correct. As I said before, you need to take a course in aerodynamics, not try to reinvent the science.

Sorry I could not plant the seed of doubt in your mind...

Flight physics say the Me-109G out-turns, in multiple consecutive sustained slow speed level turns, an early slightly underpowered needle-tip prop P-47D Razorback.

The reason they say that is because they are ****.

Cheers,

Gaston

 

[mhuxt]

Now, that's some hubris right there.

 

[Elmas]

Years ago a very important Maths magazine received from an Italian University some papers with extremely difficult formulas, something written in this way

The magazine published all the papers ....that of course were completely false.
( those above are true: they are the solutions of differential equations, very important in aerodynamics).

.... the signature of the Author was " ***** *******" someting like, in English.......... "En*ous Bu***t"......

 

[wuzak]

If it isn't scaleable then it probably isn't true.

For scale testing you need to do some of this:
Dimensional analysis

Aerodynamicists have been using this for many years since it isn't always practical to test full size aircraft. Using Dimensional analysis the aerodynamicist can figure out what scale model to use and what wind speeds to test.

I think you would also need to do the same for structural strength, since you seem to be worried about deflections.

Wind tunnel testing should also be more repeatable than flight testing - scale or full size.

So Gaston, how good are you at maths?

 

[Jenisch]

I don't know what genius like Gaston are always doing discussing in the internet when they can revolutionize their fields.

 

[FLYBOYJ]

Imagine the vertical height of the prop, then put the micro-second initial pivot point at the bottom 20% height... If you increase AoA, the top of the prop by definition moves back compared to the trajectory, but here it does so for a micro second by dipping the CL and pivoting within the prop's face...

And did you ever consider that the prop bends too?

You would know that if you knew how much the wings actually bend in flight, but you don't. Hence my inquiry about methods to find that out with strain gages, full scale in case the effect is not scaleable, and matched to static values with wings bent on the ground to evaluate the extent of the actual bending in flight... All of which we now seem to agree was never done on WWII fighters (except for the static on-the-ground part).

While strain gauges did a lot to enhance gaining in flight stress information one could calculate very accurately the amont of bend a wing would experience in flight based on static testing. Strain gauges provided a reality check of what was calculated. Strain gauges in the bigger picture is a tool used for fatigue calculations rather than load testing. Read about Anne Burns and her work on the de Havilland Comet.

I still see a lot of hot air rising...

 

[Shortround6]

I believe there was also a lot photography work done, both movies and stills, of wings both on aircraft in flight and in wind tunnels. Wind tunnels used both the wool tuft and smoke to study air patterns while in flight tests used the wool tuft.
Some aircraft were tested with different airfoil sections on parts of the wing. I would think that somebody might have noticed if the lift,drag and airflow in all these experiments didn't go along with the calculated values. Or if it didn't that th e calculations were sometimes modified.

 

[FLYBOYJ]

I believe there was also a lot photography work done, both movies and stills, of wings both on aircraft in flight and in wind tunnels. Wind tunnels used both the wool tuft and smoke to study air patterns while in flight tests used the wool tuft.
Some aircraft were tested with different airfoil sections on parts of the wing. I would think that somebody might have noticed if the lift,drag and airflow in all these experiments didn't go along with the calculated values. Or if it didn't that th e calculations were sometimes modified.

Spot on

 

[davparlr]

An entertaining site if one doesn't try to make out the logic. Gaston's post logic, or lack of, kind of remind me of a little puzzle my Dad us to say, "if it took a hen and a half a day and a half to lay an egg and a half , how long would it take a grasshopper with boots on to kick the seeds out of a dill pickle?". I never came up with an answer.

In reality, aerodynamics is a complex issue with multiple factors inter-playing. Many analysis techniques simplifies the interaction with approximate algorithms and/or assumptions, e.g, airflow will be subsonic, or, air is an incompressible medium like water. Over time, these calculations have been proven very accurate by wind tunnels, flight test, and in actual performance. In addition, now days, powerful computers can iron out even the slight variances to the point that performance rarely vary from the calculated data as verified in rigorous flight test. It is typical now that aircraft now behave as the simulators predict. To think this isn't so is as irrational as trying to predict how long it is going to take that grasshopper to kick those seeds.

 

[wuzak]

And did you ever consider that the prop bends too?

And prop shafts, engines, engine mounts, fusealges, etc.