Top E Planes

[Karnak]

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Brewster
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No.  Brewster is absolutely terrible at holding its E.

[bozon]

There are several kind of "holding E":

Speed bleed at higher than max level speed
This refers to diving into a speed the plane cannot sustain and waiting for the speed (kinetic energy) to sip away. Specific drag (drag/mass ratio) is very important here. Also engine power and some properties of the prop help because at high speeds the prop produces drag.

Speed bleed while maneuvering
This refers to energy bleed while pulling G. In addition to form-drag, induced drag play a large role. Induced drag roughly behaves like the lift squared (D~L^2) and if we are maintaining a constant G, that means also D~G^2. The exact proportionality depends on the wing-loading (because less weight means less lift is required to maintain G) and the properties of the wing. A spitfire has large wings for its mass that provide quite low mass loading and they are elliptical, a shape that reduce the induced drag. This is why Spits keep their speed up "well" even in a high G turn. I have seen Yak3s with a dead engine keep fighting, scissoring, circling a base and landing with what seemed like minimal energy loss while maneuvering. Not sure why, but I did not check its wing loading numbers. Most other planes would have fallen out of the sky if they tried that.

Now, planes do not have to hold their E - they can spend it and immediately replenish it by engine power. Therefore, high power loading can replace aerodynamic efficiency in "keeping E" and the engine helps in sustaining hard turns. La7s and 109K4s immediately come to mind as examples. There are planes that combine several qualities - Spit16s and Yak3s have a good power loading and seem to suffer very little from drag at high G.

[FLS]

• When I am in a jug dropping like a brick from 12k, level off on the deck at 500+ mph, then see a Spit16 or N1k 600 out on my 6.  I wonder what to call that aspect of the plane that enables that.  ...AND what planes do that best.
• When oldcoot SKOOLZ me in his P-51 where we engage with him being just slightly higher than me.  He did this by maintaining significantly greater alt and speed leaving me few choices.

In these instance it is not just pilot ACM skills (though oldcoot certainly has them).  The pilots in these and similar cases are taking advantage of __________ (insert preferred technical term).  I simply want to learn what IT is and get good at using IT.  I think we all would, who have not already mastered it.

Thanks all for your posts and advice.

Specific questions like those are more useful. You can get your best answers when you have film. 

[FLS]

Bozon you're using energy bleed to illustrate energy retention.

[FLOOB]

Unlike diving, weight affects zoom climbing because zoom climbing is all about momentum and inertia. That's why the b239, which is less than half as heavy as an f6f, is a crappy zoomer. Sometimes people confuse zoom climb with "hanging on the prop" like in a roping stallfight or something.

[FLS]

Unlike diving, weight affects zoom climbing because zoom climbing is all about momentum and inertia. That's why the b239, which is less than half as heavy as an f6f, is a crappy zoomer.

That is not correct. You zoom against drag from air resistance and gravity, but in a climb it's mostly gravity and the drag from gravity is proportional to mass.

[FLOOB]

Inertia is proportional to an objects mass, gravity affects all objects equally regardless of mass. Gravitation is proportional to mass, but that has nothing to do with airplanes.

[FLS]

Inertia is proportional to an objects mass, gravity affects all objects equally regardless of mass. Gravitation is proportional to mass, but that has nothing to do with airplanes.

Then why does a heavier aircraft require more lift?

[FLOOB]

The same reason an aircraft carrier requires more thrust than a jet ski. Or more to the point with regards to E retention, the same reason an aircraft carrier requires more force to decelerate than a jet ski requires. Inertia.

Also a zoom climb isn't a product of lift it's a product of ballistic, or kinetic energy. In fact another term for zoom climb is ballistic climb, it's a climb in which an aircraft exceeds it's climb rate by expending it's momentum upward. Just like any ballistic object, the heavier it is, the more it takes to stop it.

[BaldEagl]

Are you ignoring fuel? Fuel is part of the total energy package.  

So you're saying a glider doesn't have E?  I disagree.  Speed (kinetic energy) an altitude (potential energy) are the only components of E.  Show me a reputable source that adds fuel to that equation.

Thrust, lift and drag act on E.  The only effect fuel has is allowing an engine to run thus producing thrust but fuel in and of itself has nothing to do with E.  

And you can retain E.  As long as you hold the same overall balance of speed and altitude you've retianed E.  Gliders do it all the time.  If all they did was lose E they wouldn't fly very long but, in fact, they can stay aloft for very long times and again, they do so without fuel.


And yes, heavier aircraft typically, but not always, zoom climb better than lighter ones.  It's because the E reducing forces have to work against a much larger mass.  Think of it this way; if you had a bicycle and a train both rolling toward you at the same speed without power which would you have a harder time stopping?

[FLS]

The same reason an aircraft carrier requires more thrust than a jet ski. Or more to the point with regards to E retention, the same reason an aircraft carrier requires more force to decelerate than a jet ski requires. Inertia.

Also a zoom climb isn't a product of lift it's a product of ballistic, or kinetic energy. In fact another term for zoom climb is ballistic climb, it's a climb in which an aircraft exceeds it's climb rate by expending it's momentum upward. Just like any ballistic object, the heavier it is, the more it takes to stop it.

It's gravity that gives it weight and it's gravity that slows it down until it stops climbing.

[FLS]

So you're saying a glider doesn't have E?  I disagree.  Speed (kinetic energy) an altitude (potential energy) are the only components of E.  Show me a reputable source that adds fuel to that equation.

Thrust, lift and drag act on E.  The only effect fuel has is allowing an engine to run thus producing thrust but fuel in and of itself has nothing to do with E.  

And you can retain E.  As long as you hold the same overall balance of speed and altitude you've retianed E.  Gliders do it all the time.  If all they did was lose E they wouldn't fly very long but, in fact, they can stay aloft for very long times and again, they do so without fuel.

Sailplanes require thrust to fly. I'm aware of the lack of engine, excepting motor gliders of course. The fact that their trust comes from gravity doesn't change the fact that all aircraft convert energy in order to fly. 

[FLOOB]

That is not correct. You zoom against drag from air resistance and gravity, but in a climb it's mostly gravity and the drag from gravity is proportional to mass.

Im not busting your chops. But it is important to me that you understand that drag from gravity is not proportional to mass. If one dropped a BB and a cannon ball at the same time from the tower of Pisa, the BB and the cannon ball would both hit the ground at the same time.
Or if you dropped a feather and a hammer at the same time in a vacuum..

http://youtu.be/5C5_dOEyAfk

[bozon]

Bozon you're using energy bleed to illustrate energy retention.

Because they refer to the same thing. Less energy bleed is the same as more energy retention. For me it is more convenient to think in terms of what makes me lose energy, rather than how much energy I get to keep.

[FLS]

Im not busting your chops. But it is important to me that you understand that drag from gravity is not proportional to mass. If one dropped a BB and a cannon ball at the same time from the tower of Pisa, the BB and the cannon ball would both hit the ground at the same time.
Or if you dropped a feather and a hammer at the same time in a vacuum..

http://youtu.be/5C5_dOEyAfk

You seem to be saying that gravity doesn't affect things equally going up, just going down. I'm saying it's the same in both directions.
It's because gravity is proportional that the hammer and feather fall together in a vacuum. Greater mass has greater inertia and requires greater force to accelerate. Works both ways.

Because they refer to the same thing. Less energy bleed is the same as more energy retention. For me it is more convenient to think in terms of what makes me lose energy, rather than how much energy I get to keep.

I'm not disagreeing with you. My point is that referring to energy is not the best way to talk about speed and altitude. I understand that people generally refer to energy as being the speed and altitude of an aircraft and that it's a simplified explanation of energy. I agree it's important for people to understand how we trade kinetic and potential energy and how we combine them to compare relative energy states. However the word energy is often used when the words speed or altitude would be clearer and easier for less expert readers to understand.

Saying that turning hard bleeds E is not as descriptive as saying that turning hard slows you down. It's confusing for the guys trying to learn ACM and leads to nonsense like "spits hold E better in turns". Every aircraft slows down when you increase drag. Every aircraft retains all it's speed and altitude when you maintain level flight and don't increase drag. What Spits do, as you know, is allow a higher load factor at slow speeds than many other of our fighter aircraft. Describing that as holding E better isn't a useful description. Saying that they have lower stall speeds and/or better sustained turns is simpler and easier to quantify.

The OP had at least 4 good questions rolled into his first one but thinking in terms of the best energy retaining aircraft wasn't helping him.
Fortunately training is available.