GregP
Major
Mass only cancels out if the masses of two different aircraft are nearly equal. If they are substantially different, then the masses make a big difference.
Zoom Climb
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You are still not understanding. We are not talking about TWO different aircraft.
We are talking about ONE aircraft with a lot of KE in level flight and converting that KE into PE for altitude.
It is the SAME aircraft, so mass doesn't change except for a small amount of fuel burned during the zoom.
You can put as much weight as you like into Fokker Tri plane and it doesnt affect the maximum speed in a dive because the wings come off. The Hurricane with fabric and dope wings was heavier than one with metal wings but the maximum dive speed was lower, because the fabric started to balloon and tear.
Thumpalumpacus
Major
Thumpalumpacus
Major
Doesn't mass retain inertia better?
GregP
Major
How can it be the SAME aircraft? We've been talking about zoom climb comparisons. If you only have one airplane, then it can't zoom climb better or worse than itself. It can only climb better or worse versus some other airplane that almost certainly doesn't mass the same.
If you compare, for instance, a P-40N versus a Spitfire V, then the P-40N will be about 8,500 pounds and the Spitfire V will be about 6,300 pounds. The P-40 is about 35% heavier and thus, at the same altitude and speed, has about 35% more PE and about 35% more KE since ET = mgh + 1/2 m V^2; and g, h, and V are the same, leaving only mass as the difference. One airplane has only itself to compare with. It doesn't make sense to be talking about only one airplane and put the word "comparison" in the sentence. Compare implies more than one choice.
If you have a P-36 and P-40 loaded to the same weight, at the same height and velocity, producing the same power, then you can compare them. They will NOT zoom-climb the same.
Hello PBehn,
We are discussing Zoom Climbs, not Terminal Velocity Dives.
We are starting off in Level Flight at some speed and trade off that speed for altitude which means we end up going only slower.
The question I was asking GregP was whether he thought an aircraft would zoom higher or faster if it had the SAME aerodynamics but just additional weight.
When we start talking about structural limitations of various airframes and when they fall apart in a dive, it becomes a whole different subject.
Absolutely!
Increased Mass retains Inertia better but it also gets pulled down harder by Gravity.
Funny thing is that the two balance out EXACTLY which is what a fellow named Galileo is supposed to have proved at the Tower of Pisa. That is why all objects fall at the same speed and acceleration with differences being the result of the relative effects of air resistance.
Hello GregP,
This is getting frustrating.
Please go back and read post #20.
I know you quoted it but I don't think you actually read it.
Lets take your examples:
P-40N at 8500 pounds going 300 MPH - KE = (M * V^2) / 2
P-40N at 5000 feet altitude going 0 MPH - PE = M * G * H
Same aircraft. Same Mass. Mass is in both KE and PE equations. They cancel out when compared.
Spitfire at 6300 pounds going 300 MPH - KE = (M * V^2) / 2
Spitfire at 5000 feet altitude going 0 MPH - PE = M * G * H
Same aircraft. Same Mass. Mass is in both KE and PE equations. They cancel out when compared.
Since you apparently didn't like the Thunderbolt in earlier example, Lets use Corsairs this time.
Suppose we have two identical Corsairs. The only difference is that one has a full ammunition load and full fuel while the other has no ammunition and minimal fuel.
Both are at the same altitude and speed pull into Zoom climbs at the same angle.
Which will zoom faster or further and why?
You cannot have the same aerodynamics, whatever weight you have needs to be lifted, that lift is provided by the wings, to change from level flight you need to increase the AoA to provide that lift and climb, to climb with more weight needs more lift. I associate zoom climb to be a climb rate from a speed not attainable in level flight as in "boom and zoom" tactics, obviously you dont, could you please clarify the difference between "zoom climb" and "maximum climb rate" in your thinking.
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Are you discussing it being easier to climb with more weight?
Thumpalumpacus
Major
If all objects fall at the same speed (per Galileo), but more mass retains more inertia (per Newton), wouldn't that leave a heavier aircraft with more inertia as it begins its climb out of a dive?
I'm not studied in physics and am not equipped to argue that, but it seems odd to me that if gravity works the same no matter the mass, but inertia is tied to mass, why mass wouldn't have an impact on a zoom climb. Per 2LOT that energy has to go somewhere. Might you explain further?
You are correct. An aircraft with twice as much mass (weighing twice as much) would have twice as much inertia resisting change in velocity.
Note that for all practical purposes Weight is proportional to Mass, so the aircraft with twice the mass and twice the inertia also has twice the Gravitational attraction (gravitation acceleration) slowing it down as it climbs or speeding it up as it dives.
Per Newton, we have F = M * A
but F == M * G(The Gravitational Constant) so A is the same.
The Kinetic Energy DOES go somewhere. It gets transformed into the Potential Energy of the Mass of the Aircraft at a greater height.
Thumpalumpacus
Major
So mass does indeed have an impact on zoom?
In post #20 I did mention that the induced drag would be a bit higher for the heavier Thunderbolt.
At fairly low altitudes, the difference in AoA and induced drag is amazingly small which is why higher weight in an aircraft up to a point doesn't make a significant difference in maximum speed.
I see a Zoom Climb as a climb at a speed higher than that at which the aircraft achieves its maximum sustained climb rate.
As an example, I will use the A6M2 Reisen.
Its best sustained climb rate was at an airspeed of just over 120 MPH.
If it is trying to climb at a speed higher than that, it is in a Zoom Climb.
If it starts a climb at 300 MPH at low altitude, it may not have exceeded its maximum attainable level speed but it is still a Zoom Climb.
So does Mass alone have an impact on Zoom?
I will leave that determination up to you but you already know my opinion.
GregP
Major
Sorry Ivan, I was addressing the OP's first post, not post # 20.
So, we have identical airplanes with just weight and CG differences.
I'll choose the lighter one as the best overall climber, but with assumptions.
1) They leave the power settings the same, meaning the lighter airplane has the better power-to-weight ratio regardless of what power is selected ... unless they both remove all power. But, removing all power and then trying to climb doesn't make any kind of operational sense, so I'll neglect that possibility.
2) The airplanes are identical, meaning the drag is the same since they are at the same speed and altitude. The lighter one should decelerate a bit quicker from profile drag, but they both leave the power in, so it hasn't much effect in reality.
I'd expect the heavier one to have a better initial zoom but, practically speaking, better might not translate into much of a difference. Once zoom is done, the lighter one should climb away from the heavier one, but not too rapidly. There will be some altitude above zoom and after sustained rate of climb where the two will be identical in time, after which the lighter one should climb better. Not too sure by how much, but it won't be by a large amount.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
Good stuff!
In a vacuum with no aerodynamic effects, No.
If we add Engine Power, the advantage goes to the Lighter aircraft.
If we add Air Resistance, the question becomes How Much Air Resistance / Drag.
If the Air Resistance is very high in relation to the Energy being bled off by the altitude gain, I believe that the heavier aircraft may have an initial advantage but it would be VERY short. It certainly would not last until both aircraft reached their airspeedS for best sustained climb rate because if Engine Power is the same, the lighter aircraft is able to replace proportionally more of the energy it is losing due to the altitude gain.
The air resistance would be pulling off the Kinetic Energy of both aircraft, but the heavier aircraft has more KE to lose.
The Altitude Gain is converting KE to PE but it affects both aircraft the same.
Engine power is replacing some energy of both aircraft but it takes less energy to accelerate or raise a lighter object.
Note also that we are talking about airspeedS for best sustained climb because the heavier aircraft will hit its best climb rate at a higher airspeed and the actual climb rate will be lower.
GregP
Major
In a vacuum, there will be no lift, so there will be no climb, zoom or otherwise. Therefore mass DOES have an impact on zoom climb since there must be air and air resistance in order to produce lift ... unless this is pointless question to harass people who have enough interest to spend time thinking about it ...
Are you laughing, Ivan1GFP? If it ain't fun, what's the point?
Maybe our reach exceeds our grasp.
Are you laughing, Ivan1GFP? If it ain't fun, what's the point?
Maybe our reach exceeds our grasp.
Here is a silly question for you:
If an aircraft goes vertical when translating KE to Altitude, is it considered a Zoom Climb?
If so, Where is the lift when an aircraft is going vertical?
