Author Topic: F4u4"C" (Read 2642 times)

Captain Virgil Hilts · « **Reply #45 on:** January 31, 2007, 07:20:46 PM »

You'd be wrong about the drag car. You do have to steer them, in fact they get somewhat nasty when you pop the chute, especially the shorter wheelbase cars. The force doesn't really tend to plant your hands on the wheel, either.

Krusty · « **Reply #46 on:** January 31, 2007, 07:25:05 PM »

Fair enough. That was speculation.

I still would like to know the math behind 450 to 110 in 15-20 seconds being less than 1G.

Krusty · « **Reply #47 on:** January 31, 2007, 07:28:23 PM »

1mph = 5280 feet per hour.
which = 88 feet per minute
which = 1.466... per second

Times 340mph (from the f4u4) you get 498.666... feet per second.

I don't think that's right, either.

Widewing · « **Reply #48 on:** January 31, 2007, 07:28:37 PM »

Quote

Originally posted by Krusty
I don't buy that. What math did you use? I mean what did you do to get 32.2feet/sec? As near as I can tell it's not a straight deceleration as there's sidslip and drag slowing it down, not a ground or surface. How do you get distance? (the feet/sec part I mean)

EDIT: By this I mean I'll admit I'm wrong if I'm wrong, but I'm not seeing how you got from A to B

If we ignore air resistance, an object falling freely increases in speed by 32.17 ft/sec for each second it free falls. Therefore, a free falling object (in a vacuum) accelerates at 1 G.

Note also that deceleration is really acceleration in the opposite direction of motion. Ponder that....

As for me, I'm a Professional Engineer who designs acceleration sensors for a living. In fact, I'm the only Engineer who does this in our company and we are the industry leader in this technology. I've been doing this job for over 27 years. Go here and click on the Mercury Free Motion Switches link.

My regards,

Widewing

Poem · « **Reply #49 on:** January 31, 2007, 07:29:03 PM »

the acceleration at which all bodies of matter fall to the center of the earth is 9.8 (rounded, mind you) meters per second per second.

This converts to roughly 32 feet per second per second.

This value is one G.

You decelerated the F4U at roughly 17 feet per second per second.
This comes to .53125 G's.

Think of it this way.
You are strapped to a car seat bolted to your roof. In the sitting position, you are facing down, your stomach to the floor. I can completely assure you that you would be able to play with your computer joystick in the scenario. And as a matter of fact, imagine that everything, including your body weight almost half of what it normally does. And furthermore, everything in the aircraft you would be flying is completely connected to each other. So, in your scenario of being bolted to the roof, imagine that your friend is holding your joystick comfortably in front of you. In the linear forward motion, the ability of you to control the aircraft would be, most likely, absolute.
Now we should take in consideration of the vertical motion. In the video, i would assume that the maximum vertical G's would be around maybe 5 G's (the gauge only reads to 4, but from the view, I doubt you would have been gaining so much altitude to break 6 Gs at maximum, though this is a guess). If you are a fighter pilot, and cannot control your aircraft in a environment between -3 and +6 G's, you should in no way be piloting a fighter aircraft. The trained human being can handle these forces naturally.

Thus, a trained F4U pilot should most definitely be able to handle these conditions, and I would assume an average person would be, most likely, able to survive in it as well.

Krusty · « **Reply #50 on:** January 31, 2007, 07:35:51 PM »

Quote

Originally posted by Poem
the acceleration at which all bodies of matter fall to the center of the earth is 9.8 (rounded, mind you) meters per second per second.

This converts to roughly 32 feet per second per second.

This value is one G.

You decelerated the F4U at roughly 17 feet per second per second.
This comes to .53125 G's.

Think of it this way.
You are strapped to a car seat bolted to your roof. In the sitting position, you are facing down, your stomach to the floor. I can completely assure you that you would be able to play with your computer joystick in the scenario. And as a matter of fact, imagine that everything, including your body weight almost half of what it normally does. And furthermore, everything in the aircraft you would be flying is completely connected to each other. So, in your scenario of being bolted to the roof, imagine that your friend is holding your joystick comfortably in front of you. In the linear forward motion, the ability of you to control the aircraft would be, most likely, absolute.
Now we should take in consideration of the vertical motion. In the video, i would assume that the maximum vertical G's would be around maybe 5 G's (the gauge only reads to 4, but from the view, I doubt you would have been gaining so much altitude to break 6 Gs at maximum, though this is a guess). If you are a fighter pilot, and cannot control your aircraft in a environment between -3 and +6 G's, you should in no way be piloting a fighter aircraft. The trained human being can handle these forces naturally.

Thus, a trained F4U pilot should most definitely be able to handle these conditions, and I would assume an average person would be, most likely, able to survive in it as well.

Okay I understand that, only I decelerated the f4u at 17mph/sec, not feet/sec. How do I get from mph/sec to feet/sec/sec?

Poem · « **Reply #51 on:** January 31, 2007, 07:37:32 PM »

Quote

Originally posted by Krusty
Fair enough. That was speculation.

I still would like to know the math behind 450 to 110 in 15-20 seconds being less than 1G.

Given information: 32 ft/s/s = 1 g

Math: 450-110 = 340 feet per second
340 ft per sec / 15 sec = 22.66666666666666~ feet per second per second

22.66666666666666/ 32 = .7

the maximum of this is .7 g, which is less than 1 g.

Krusty · « **Reply #52 on:** January 31, 2007, 07:40:02 PM »

Quote

Originally posted by Poem
Given information: 32 ft/s/s = 1 g

Math: 450-110 = 340 feet per second
340 ft per sec / 15 sec = 22.66666666666666~ feet per second per second

22.66666666666666/ 32 = .7

the maximum of this is .7 g, which is less than 1 g.

No, because mph is not feet. It was 340mph in 20 (possibly 15?) seconds.

It was at the low end (using 20 secs) 17mph/sec. At the high end (15 seconds) it was 22mph/sec.

miles per hour are not feet per second, so I dunno how you go from one to the other.

EDIT: What, is it simple math? Even if you do 32*60*60 to get feet per hour per second, then divide by 5280 you get 21.8181...

Poem · « **Reply #53 on:** January 31, 2007, 07:43:11 PM »

Quote

Originally posted by Krusty
Okay I understand that, only I decelerated the f4u at 17mph/sec, not feet/sec. How do I get from mph/sec to feet/sec/sec?

my lord your right.

now for good ol' equations!

1 mph = 1.467 ft per sec

340 x 1.467 = 500

500 / 20 = 25 feet per second per second

500 / 15 = 33 (just slightly over 1 g)

Really, for the sake of argument, its so close it does not even matter, though you were right in that regard. Still, the idea of a persons ability to handle the situation still holds true, it is absolutely possible.

Widewing · « **Reply #54 on:** January 31, 2007, 07:45:53 PM »

Krusty, a simple online primer on Newtonian Physics.

It's an easy to read introduction into Newton's laws of motion. It may help.

My regards,

Widewing

Krusty · « **Reply #55 on:** January 31, 2007, 07:46:59 PM »

It seems that way, yes. Such rapid decelleration, though... hard to believe it's such minimal impact.

Poem · « **Reply #56 on:** January 31, 2007, 07:48:46 PM »

Just to put it out there, a modern F/A-18 E superhornet lands on the deck of an aircraft carrier at around 170 knots.

170 knots = roughly 200 miles per hour

they come to a complete halt after catching the cable in about 3 seconds.

200 mph = about 300 feet per second

300 ft/s / 3 seconds = 100 feet per second per second, well over 3 g's.

I have never heard anything about a pilot of a F/A-18 red out during a carrier landing. I have also never heard of any losing hand of the aircraft controls.

Poem · « **Reply #57 on:** January 31, 2007, 07:49:55 PM »

Quote

Originally posted by Krusty
It seems that way, yes. Such rapid decelleration, though... hard to believe it's such minimal impact.

My dear friend, it is not rapid at all. It is actually quite slow considering the accelerations achievable by manned craft, and other situations that arise in real life.

F4UDOA · « **Reply #58 on:** January 31, 2007, 10:05:18 PM »

Not that anyone is still watching the original subject of the post but there is some evidence of the F4U-4C during the war. In fact Vought records show all F4U-4/4B/4C ptoduction in 1944. When they were delivered may be another story.

I am not saying that they were in combat just that they were indeed produced if not retrofitted. I remember reading the wings could fit either .50 cal or 20mill

Here are two pics from the Vought website, they are the same airplane from different angles (nose markings) and dated in July 1945 labeled F4U-4C and clearly is a F4U-4C showing the short barrel M-3 cannon.

Bodhi · « **Reply #59 on:** January 31, 2007, 10:31:23 PM »

Good post F4uDOA.

I did not have time to get to the production data today. It is a pain in the arse going through those micro films as much of it is in poor condition. I was farly sure I had seen the F4u-4b's being produced in '44. I think most were retrofitted though to carry the .50's.

As for standard -4 wings being able to carry 20mm's like the -4B, well, that is a yes and no answer.

Yes, a -4 could carry 2 20mm. Not 4. The wing is not designed without modification to allow for 4 20mm. First off, in the standard -4 wing, the inbd gun slots are larger allowing for the larger weapon. The inbd spent ammunition holes are larger too. The kicker though is the ammo can slots. Only the forward guns are capable of being widened by the removal of the cap skin and forward structure. This allows the much larger can for the 20mm to fit.

If I have time tomorrow, I will try to post some pics to show the difference between the cans, and the internal structure of the wing so you can better visualise it.