Author Topic: Top E Planes  (Read 6825 times)

Offline Badboy

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Re: Top E Planes
« Reply #105 on: January 23, 2014, 02:27:38 PM »
Did Galileo ever drop anything which had powered flight?

Exactly, you can't use a dubious ballistics experiment to draw conclusions about atmospheric flight in high powered aircraft.

Badboy
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Offline BnZs

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Re: Top E Planes
« Reply #106 on: January 24, 2014, 12:01:05 AM »
Galileo used balls of various weights rolling down inclined planes. Their rate of acceleration was easier to time.
"Crikey, sir. I'm looking forward to today. Up diddly up, down diddly down, whoops, poop, twiddly dee - decent scrap with the fiendish Red Baron - bit of a jolly old crash landing behind enemy lines - capture, torture, escape, and then back home in time for tea and medals."

Offline save

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Re: Top E Planes
« Reply #107 on: January 24, 2014, 05:57:54 AM »
The reds always to try to nail my wingman Bozon too.


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Offline Badboy

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Re: Top E Planes
« Reply #108 on: January 24, 2014, 07:20:55 AM »
Galileo used balls of various weights rolling down inclined planes. Their rate of acceleration was easier to time.

How ever he did it, his conclusion still leads people to believe that when you drop two objects the weight won't affect how they fall.

The example I gave earlier shows that if you dropped 6lb and 36lb cannon balls from the Empire State building the heavy one would hit the ground while the lighter one was still passing the 5th floor. That is a very different image, with a drop of 1250ft the balls land with a separation of more than 48ft that's 96 times the diameter of the larger ball over an altitude which for aircraft is fairly small.

That's why when real pilots discuss dives and zooms the weight of the aircraft is an important consideration. It is important because for atmospheric dynamics the mass of an object really does matter.

Regards

Badboy
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Offline BnZs

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Re: Top E Planes
« Reply #109 on: January 24, 2014, 08:52:01 AM »
I have been told that the ballistic properties of fighter airplanes are really minor factors compared to its ratio of thrust to weight and drag as long as the engine is running, to the point that for example, a zoom climb from 400 TAS in a Pony with 25% fuel ought to be higher than a zoom from 100% fuel Pony under the same conditions, because the thrust/weight advantage more than makes up for the "ballistic" advantage of having more weight. Is that true?

How ever he did it, his conclusion still leads people to believe that when you drop two objects the weight won't affect how they fall.

The example I gave earlier shows that if you dropped 6lb and 36lb cannon balls from the Empire State building the heavy one would hit the ground while the lighter one was still passing the 5th floor. That is a very different image, with a drop of 1250ft the balls land with a separation of more than 48ft that's 96 times the diameter of the larger ball over an altitude which for aircraft is fairly small.

That's why when real pilots discuss dives and zooms the weight of the aircraft is an important consideration. It is important because for atmospheric dynamics the mass of an object really does matter.

Regards

Badboy
"Crikey, sir. I'm looking forward to today. Up diddly up, down diddly down, whoops, poop, twiddly dee - decent scrap with the fiendish Red Baron - bit of a jolly old crash landing behind enemy lines - capture, torture, escape, and then back home in time for tea and medals."

Offline Badboy

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Re: Top E Planes
« Reply #110 on: January 24, 2014, 04:37:36 PM »
I have been told that the ballistic properties of fighter airplanes are really minor factors compared to its ratio of thrust to weight and drag as long as the engine is running, to the point that for example, a zoom climb from 400 TAS in a Pony with 25% fuel ought to be higher than a zoom from 100% fuel Pony under the same conditions, because the thrust/weight advantage more than makes up for the "ballistic" advantage of having more weight. Is that true?

No, it is not true.

Let's have a look at the math again.

For a ballistic zoom the acceleration would be:

a = -g - D/m

For a power zoom the acceleration would be:

a = -g + (T-D)/m

In both cases if you keep everything constant but the weight the heavier aircraft will zoom higher.

Let's take a closer look at your example of the two P51s in a vertical zoom at 400mph with one at 100% fuel and one at 10% fuel. Putting in values for gravity, mass, thrust and drag and calculating the deceleration for each, then using those values with the 400mph start speed we can calculate the time for each aircraft to slow to 150mph. Then we can use those times to calculate the distance zoomed during that time. What happens in both cases is that the heavier aircraft has less deceleration so it zooms for longer and zooms higher. In the first case with no power the heavier aircraft zoomed 180ft higher than the lighter one. Under maximum power of course both aircraft zoomed higher than in the first example but the difference between them was less at 140ft.

That's a difference in zoom of between 4 and 5 aircraft lengths just based on fuel load. Factor in dissimilar aircraft with big weight differences and different props and drag and the situation gets more complicated but when you have heavy American aircraft with powerful engines and paddle blade propellers the difference would be even greater in favor the heavy aircraft to the extent that it would have been tactically significant both in zooms and dives.

I can't recall specific examples right now, but I'm sure I have read a number of anecdotal accounts by WWII pilots that verifies that. 

Regards

Badboy
« Last Edit: January 24, 2014, 04:41:25 PM by Badboy »
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Offline BnZs

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Re: Top E Planes
« Reply #111 on: January 24, 2014, 06:11:30 PM »
Okay. When I tested zoom climbs from 400 from several different a/c in-game, almost all of them seemed to get 6000 feet and some change back, except the P-38 which got a full 7K.
"Crikey, sir. I'm looking forward to today. Up diddly up, down diddly down, whoops, poop, twiddly dee - decent scrap with the fiendish Red Baron - bit of a jolly old crash landing behind enemy lines - capture, torture, escape, and then back home in time for tea and medals."