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It is not hard to do the math Nikademus. I know you would be able to do it.
Basic premise is to determine our lift/drag forces in 1 G level flight solve for parasitic component of drag, and then use our power available to find the increase in induced drag if we maximize our turn from that level condition of flight.
I also not into your attitude towards me either. If you were more secure in your position, I don't think I would be explaining my comment to you. It would be self evident. If you have worked so hard in the industry, WHY AM I EXPLAINING EAS TO YOU???? I have never had to explain that to someone who is versed in aeronautical science, it is a given and industry standard.
The dynamic pressure remains constant over EAS. Dynamic pressure changes over TAS.
Co-efficient of lift and drag are nothing more than the ratio of dynamic pressure to lift or drag pressures.
Holding our dynamic pressure steady gives a basis to compare aircraft performance. This is why engineers use EAS for performance comparison purposes.
When we convert from EAS to TAS, the aircraft has nothing to do with it. The conversion is based on the physical properties of the atmosphere.
EAS just eliminates the density differences in the atmosphere as a factor.
Since our original poster placed data from different altitudes, I simply eliminated the altitude as a factor for comparison.
Yes, the poster is also listing what appears to be TAS at higher altitude.
This tells us absolutely nothing about the relative velocity. To do that we must convert to EAS.
The effect of altitude is to increase velocity by the SMOE. An aircraft traveling a velocity of 200KEAS at sea level is traveling 200KTAS.
An aircraft traveling 200KEAS at 35,000 ft is traveling 326KTAS.
Both aircraft however are traveling at exactly the same velocity of 200KEAS and neither aircraft has any speed advantage. One just benefits from the effects of altitude.
A quick SWAG of altitude effects using the data provided in this thread shows the Bf-109K4 to be traveling at an equivalent airspeed of 299mph while the P-47N is traveling at 272mph.
440mph / 1.4678<SMOE FL24> = 299 mph EAS
467mph / 1.71295<SMOE FL325 = 272mph EAS
The Bf-109K4 is the faster of the two aircraft according to this data.
Yes, the poster is also listing what appears to be TAS at higher altitude.
This tells us absolutely nothing about the relative velocity. To do that we must convert to EAS.
The effect of altitude is to increase velocity by the SMOE. An aircraft traveling a velocity of 200KEAS at sea level is traveling 200KTAS.
An aircraft traveling 200KEAS at 35,000 ft is traveling 326KTAS.
Both aircraft however are traveling at exactly the same velocity of 200KEAS and neither aircraft has any speed advantage. One just benefits from the effects of altitude.
A quick SWAG of altitude effects using the data provided in this thread shows the Bf-109K4 to be traveling at an equivalent airspeed of 299mph while the P-47N is traveling at 272mph.
440mph / 1.4678<SMOE FL24> = 299 mph EAS
467mph / 1.71295<SMOE FL325 = 272mph EAS
The Bf-109K4 is the faster of the two aircraft according to this data.
You claim that the aircraft with the highest EAS is the faster of the two.
Both aircraft are indeed going the same EAS but the aircraft at 35000 ft. is going much faster, through the air and over the ground, than the one at sea level by everyone's definition.
A light went on and I realized that this was very useful in calculating aircraft airspeed performance
I was able to find a couple of charts that showed EAS in all the flight test reports and contractor reports. This was on the F4U and showed EAS as a function of hp. A light went on and I realized that this was very useful in calculating aircraft airspeed performance if you did not have a test. By knowing the hp required for an EAS (maybe by a test at sea level or computer), and by knowing the hp output of an engine at an altitude, the EAS can be found and one can calculate TAS of the aircaft at that altitude. I suspect this is one of the major uses for EAS. Apparently it is also used in other performance items other than speed.
Again, without horsepower behavior over altitude,
Is it reasonable to suggest that TAS makes for an ok basic comparison if the two planes are at the same altitude?
all-right. That clears up some confusion.
Is that useful for a basic comparison
It is the faster of the two aircraft. Your whole argument is nonsensical.
Do you understand about the important of dynamic pressure and its relationship to aircraft performance? I really don't think you have a clue about it.
This is lack of understanding of the basic fundamentals.
I will give it my best shot to help you out.
For example:
It is a fact that the coefficients of Drag represents the ratio of drag pressure to dynamic pressure and equals DRAG PRESSURE / DYNAMIC PRESSURE.
If we want to compare our Bf-109 and our P47 using TAS, any idiot can see that the P47 is the much faster aircraft, right!
Well if we compare our DYNAMIC PRESSURE between these two aircraft using TAS:
P47 at FL325 467mph * 1.47 = 686fps
q=.5rV^2 = .5*.000840785 slugs * 686fps^2 = 197.8 psf
Bf-109 at FL24 440mph * 1.47 = 6478fps
q=.5rV^2 = .5*.00110327 slugs * 647fps^2 = 230.9 psf
Wow! Check that out. The slower aircraft has higher dynamic pressure! That can't be if our planes are under the same conditions.
Dynamic pressure is a function of speed:
q=.5rV^2
If our planes are under the same conditions, then the faster one MUST have the higher dynamic pressure. It's our frame of reference and I am sure you know how important that is in physics.
Of course we can ignore the science and just go ahead with a silly comparison of airplanes under very different conditions using TAS.
It's my opinion that you have never worked on any aeronautical science field or related to aeronautical engineering. I think your posturing was complete baloney.
You would at least have a grasp of the basic fundamentals.
On your other observation, you don't need EAS to get the effects of power. Power effects maintain the same ratios over any given velocity measurement. The effect is relative. Just keep track of your units!
Some airspeed's are more useful for certain things. IAS is very useful for flying the plane. TAS is useful for finding our Ground Speed and flight planning.
EAS is useful for performance comparisons.
Neither EAS nor TAS is very useful for comparing aircraft data recorded over different atmospheric models with different standards for the application of compressibility affects. Comparing data recorded in Germany by Mtt directly with data recorded by North American is silly and meaningless unless the data is converted to the others standards.
Obviously you do not realize that if we have TAS we do not need power data to figure EAS. All we are doing is accounting for the density effects of the atmosphere on our airspeed. Eliminate the effects of altitude and we have our EAS.
Since you felt so compelled to brag about your being an engineer and working in the aerospace industry, what part of it did you work in, again?
It's my opinion that you have never worked on any aeronautical science field or related to aeronautical engineering. I think your posturing was complete baloney.
You would at least have a grasp of the basic fundamentals.
If we want to compare our Bf-109 and our P47 using TAS, any idiot can see that the P47 is the much faster aircraft, right!
Honestly, this about as basic as you can get and all of this would be covered in a 100 level Aerodynamics course. It is readily apparent you have had absolutely no formal education whatsoever in this field.
All the best,
Crumpp
"It's my opinion that you have never worked on any aeronautical science field or related to aeronautical engineering. I think your posturing was complete baloney.
You would at least have a grasp of the basic fundamentals. "
"Since you felt so compelled to brag about your being an engineer and working in the aerospace industry, what part of it did you work in, again?"
"Honestly, this about as basic as you can get and all of this would be covered in a 100 level Aerodynamics course. It is readily apparent you have had absolutely no formal education whatsoever in this field."
Non-linear supercharger curves, the effect of exhaust thrust, Mach-dependend propeller efficiency etc.
This is true for some aircraft performance parameters, just not for airspeed comparison at different altitudes
I did assume that Germany has the same atmosphere as the US. I wasn't aware that compressibibity calculation were different in Germany. Soren, can you educate me on this? I guess you mean we must convert metrics to english or vice versa? I guess I should have thought of that.
All I was saying is that in order to maintain an EAS as you climb, hp must be constaint.
Using your quotation, here is a simpler example of the difference between EAS and actual speed. If you drive at 50 mph at sea level and stick you hand out, you will feel a certain amount of pressure, this represent EAS which would also represent TAS. If you go to the mountains at 10000 ft., and 50 mph, and stick you hand out, the pressure on your hand would be less. It is not less because you are going slower through the air, you are not, but rather because the density of the air is less (the air is thinner).
Wrong. Your speed through the AIR is slower. Your hand is at a lower dynamic pressure. I have already shown you the math on this and if you have any education in physics then you know this is fact.
You are now going at a lower EAS (< 50mph) but your actual speed through the air is the same (50mph).
NO, your speed in relation to the GROUND is the same.
Merry Christmas, Henning. I hope things are going well for you!
He does not have a point. He does not understand the basics and that is obvious.
Power effects are irrelevant to the type of airspeed as long as you maintain the same airspeed classification and the ratio relationship.
Using EAS makes "altitude changes much easier to do this in fact. Only difference in using EAS and "changing altitude" is that we only have ONE parameter to change in our analysis, the power!
You understand what I am saying right? If you want to change altitude, all we have to do if our analysis uses EAS is change the power available to the value at that altitude.
That is why it is industry standard.
TAS assumes density effects at altitude. Any values calculated using the TAS velocity are only appropriate for that specific altitude.
Using EAS eliminates this as a step and there is no need to recalculate all of our values for density effects.
It is then much easier to convert EAS to TAS if we want to account for density effects. The differences in EAS to TAS velocity are solely based on atmospheric properties alone. Two aircraft at the same EAS will have the same TAS if they are at the same altitude.
However if we want to compare aircraft performance, then using EAS puts the aircraft under the same conditions which is essential for a good comparison.
All the best,
Crumpp
Davparlr has forgotten some of this.
Keep the insults and personal attacks out of it.
In any case, this looks like a good example for my personal hobbyhorse - the overriding influence power plants have on aircraft performance!
I believe that's what Davprlr meant to point out too when he contrasted speed data points of the Me 109 and the P-47 for identical altitudes
You're right Crumpp but perhaps Davparlr has forgotten some of this. I haven't experienced Davparlr ever being dishonest, just so you know.
Merry Christmas all!