Draining E in turns

[hitech]

Just someone who has been doing those caculations for 15 years.


HiTech

[frank3]

Originally posted by GODO
When you jaw left of right, the body of the aircraft (the side surface and the rudder itself) acts as an airbrake and the aircraft slows down losing energy. When you turn left or right the brake effect comes mostly from the upper surface of the aircraft and the elevators.

Assuming this is true, planes with large upper surfaces (wings and body) should lose energy quicker than smaller planes, all that being still above stall speed, that is, still having extra lift to keep flying.

But what we see is that small planes like 190s or 109s lose E much faster than much larger ones like P51s or Spits when turning well above stall speeds.

I understand than large winged planes with smaller wingloading will keep turning tighter and at slower speed than small planes with more wingload, but the small ones should lose speed at a lower rate and the others until they reach stall speeds.

Where am I wrong?

I don't know if this is already said, but larger planes have bigger engines with more hp.
So in theory it shouldn't differ too much with small aircraft

[Crumpp]

I don't know if this is already said, but larger planes have bigger engines with more hp.

Not true.  The FW-190 and the Merlin Spitfire kept almost exactly the same Horsepower throughout their lifecycles.  Surface dimensionally the Spitfire is much larger than the 190.

 

Just someone who has been doing those caculations for 15 years.

Right,  That was my whole point to Gripen.  Your calculations are the only ones that matter since you control the artificial world of AH.

Now I am fully capable of doing the math.  The formulas are basic high school algebra.  I had to take Calc I & II, statistics, and physics in college so the math is definitely not beyond my abilities.  I am smart enough to realize that:

1. A co-efficient exists for only an exact condition of flight and applies ONLY to that condition.

2.  There are more than 1 theory and formula for most co-efficient.  These have and do change.

3.  Co-efficient are not comparable unless you know exactly how it was calculated and under what conditions.  The conditions of flight have to match exactly along with the calculations used in order to compare.

4.  Unless you account for all conditions, ie radiator drag, downwash, induced drag,  viscosity, etc....

The number you come up with is just meaningless.  It may or very well may not reflect the reality of flight.  It also has nothing to do with the level of understanding of the principals behind the math.  If you don't believe that just ask any High School Chemistry Teacher.

But I will be glad to work some formulas and smoke the ol' Texas Instruments if that is what is required to achieve some perceived level of credibility.

This is EASY to see comparing Gripens last calculations.

Crumpp

[humble]

Attention K-Mart shoppers...dead horse meat on isle 3......


Geez....

Pardon me if I'm ignorant but aren't we (you) beating to death a "non argument". I think 12 different people have stated the basic premise and mathimatical proofs on this 16 different ways. If a total idiot (me) can grasp the over all concepts why continue to beat the dead animal....

BTW you can actually crank up the film viewer and "see" relative E states in action. I do feel at times that the nikki dowsnt bleed enough e but even there you can see relative closure etc pretty easily. When you look at the speed of BOTH planes invariably you can see pretty clearly that by and large things work as they should...

[hitech]

Do the math crumpp: That is the only thing that will even put a dent in this argument. We have all done the math. It is your turn.

[gripen]

Sea level speed and output:

P-51B => 560 km/h 1480 hp
Fw 190A => 537 km/h 1740 ps
Spitfire IX => 539 km/h 1586 hp

These result following Cd0 estimates:

P-51B => Cd0=0,0164
Fw 190A => Cd0=0,0249
Spitfire IX => Cd0=0,0192

There is very little difference if compared to the values calculated for 1st FTH.

gripen

[g00b]

Crumpp the grump!

"Low wingloaded A/C have more surface therefore more drag"

Huh?

2 identical airframes will have the same parasitic drag no matter what they weigh, the lighter one will have LESS induced drag.

Can I have some of what you're smoking?

Instead of arguing with everyone, why don't you attempt to learn, there are some extremely intelligent folks posting to this thread who are trying to help you understand.

g00b

[Crumpp]

How are you figuring radiator drag?

Crumpp

[Crumpp]

2 identical airframes will have the same parasitic drag no matter what they weigh, the lighter one will have LESS induced drag.

If one has more surface area they are not identical.

But you are absolutely right.  Two Identical Airframes will have the same parasitic drag.  If one weighs more it will have more induced drag.

Crumpp

[Crumpp]

P-51B => 560 km/h 1480 hp
Fw 190A => 537 km/h 1740 ps
Spitfire IX => 539 km/h 1586 hp


Where are you getting this data?

It doesn't match anything I have seen.

http://www.fourthfightergroup.com/eagles/bs428speed.gif

http://www.fourthfightergroup.com/eagles/jl165speed.gif


http://www.terra.es/personal2/matias.s/fw190_A5_speed.gif


http://www.terra.es/personal2/matias.s/fw190-1.jpg

http://www.terra.es/personal2/matias.s/bmw801d-1024.jpg

http://www.fourthfightergroup.com/eagles/merlin66hpchart.jpg

Let me know what value you are using for radiator drag.

Crumpp

[dtango]

Here's the link to Dave Lednicer's paper.  It was a paper that was printed in Aeronautical Journal June/July 1995 and then reprinted in Sports Aviation in 1999.
Lednicer EAAjanuary1999.pdf

Tango, XO
412th FS Braunco Mustangs

[dtango]

crumpp:

I have no idea why you're even challenging gripen's calcs and why it's even germane to the conversation.  He was trying to help you understand and give you some things to work with.

I have no idea why you're even bringing up radiator drag.  If you understood the drag relationship you would realize that cooling drag is embedded in the calculations because it's contribution is already embedded in the aircraft performance numbers.  That's like asking someone to tell you the section cl at the 30% span of a wing for an aircraft when it's already accounted for in the overall wing CL which you can easily calculate.

As for challenging gripen's data points, I'm pretty confident that you are barking up the wrong tree when it comes documents he has reference to.  The man has pointed out some very interesting bits of data from some pretty obscure technical docs that exist.

Please take HT's advice and do some total drag comparative calcs on aircraft in turning situations.

Tango, XO
412th FS Braunco Mustangs

[gripen]

I just showed above how to do quick and dirty drag analyses with simple calculations using some datasets which I certainly know to be real world tested. If someone is not happy with the datasets I used, the playground is free for other datasets. I don't know if any of the charts in the Crumpp's source site are real world tested.

The P-51B speed data comes from  "Tactical Employment Trials North American P-51B-1", this data can be found from several sources including "America's Hundred Thousand"  by F. H. Dean and "The Mustang Story" by K. Delve. The engine output is calculated using engine output chart and rammed FTH of above mentioned test. Output can be also verified from US navy test data on the P-51B.

The Fw 190A speed data comes from the US Navy Fw 190 test. Output data comes directly from the chart Crumpp listed.

The Spitfire speed data is a rough average from several +18 lbs tests made by the A&AEE. Output is calculated same way as in the case of the P-51B and it can be also roughly verified from the chart Crumpp linked above.

gripen

[Crumpp]

Ok,

Did some calculations:

First I did up the Cl that was used in the Drag formula.

The weight data for the FW-190 came from Pilots Manual.  The weight data for the Spitfire came from:

http://www.fourthfightergroup.com/eagles/jl165.html

The P51D was much harder.  I ran into the same problem with the Focke-Wulf.  Empty Weight and Max Weight were easy to find but the takeoff weight of a regular fighter not burdened with extra's was slightly harder.  On site listed 10,000 lbs and another site listed 9800 lbs.  I chose the lesser weight as I felt it was the best data available.

All A/C where calculated under the following conditions:

Tempature - 65 *F
Atmospheric Pressure - 14.696 PSI

Speed = 300 mph

Using the following formula:

http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html

FW190A8 - Weight = 4272kgs
Wing Area = 735 sq. feet
Cl = .174662988

Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 831.2 sq feet
Cl = .121352522

P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .151419443

For the drag calculations I used "Cd wet" out of David Lednicer's article as they are all real world tested with his sources listed at the bottom.

http://www.thetongsweb.net/AH/EAAjanuary1999.pdf

For reference Area I used the Wing Area and the used the following formula:

http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html

FW-190 Drag = 382.85
CDw = .0071
Ref Area = 735 sq ft

Spitfire Drag = 396.27
CDw = .0065
Ref Area = 831.2 sq ft

P51D Drag = 343.56
CDw = .0053
Ref Area = 882.2 sq ft

I received this document from the Vought archives and scanned it. It shows the P-51B Cdo at .017.

David Lednicer mentions some SNAFU's over the P51's drag testing.  Seems there a bunch of calculated Cd's and even a tested Cd or two running around that are wrong.  Apparently they tested it without adding things like the exhaust stacks to the test A/C in the tunnel.  Nevertheless it does have an extremely low Cd.

P51 was an excellent fighter.

Generally speaking, Lower Wingloaded planes have more surface and therefore more parasitic drag.

Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.  

http://www.av8n.com/how/htm/aoastab.html#fig-spiral-start

In order to produce 4 tons of lift, the airplane must fly at roughly 200 knots --- twice the wings-level trim speed.

Crumpp

[Crumpp]

Ok,

Did some calculations:

First I did up the Cl that was used in the Drag formula.

The weight data for the FW-190 came from Pilots Manual.  The weight data for the Spitfire came from:

http://www.fourthfightergroup.com/eagles/jl165.html

The P51D was much harder.  I ran into the same problem with the Focke-Wulf.  Empty Weight and Max Weight were easy to find but the takeoff weight of a regular fighter not burdened with extra's was slightly harder.  On site listed 10,000 lbs and another site listed 9800 lbs.  I chose the lesser weight as I felt it was the best data available.

All A/C where calculated under the following conditions:

Temperature - 65 *F
Atmospheric Pressure - 14.696 PSI

Speed = 300 mph

Using the following formula:

http://www.grc.nasa.gov/WWW/K-12/airplane/liftco.html

FW190A8 - Weight = 4272kgs
Wing Area = 735 sq. feet
Cl = .174662988

Spitfire Mk IX Merlin 66 (+25)- Weight = 7400kgs
Wing Area = 831.2 sq feet
Cl = .121352522

P51D- Weight = 9800lbs
Wing Area = 882.2
Cl = .151419443

For the drag calculations I used "Cd wet" out of David Lednicer's article, as they are all real world tested with his sources listed at the bottom.

http://www.thetongsweb.net/AH/EAAjanuary1999.pdf

For reference Area I used the Wing Area and the used the following formula:

http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html

FW-190 Drag = 382.85
CDw = .0071
Ref Area = 735 sq ft

Spitfire Drag = 396.27
CDw = .0065
Ref Area = 831.2 sq ft

P51D Drag = 343.56
CDw = .0053
Ref Area = 882.2 sq ft

I received this document from the Vought archives and scanned it. It shows the P-51B Cdo at .017.

David Lednicer mentions some Snafu's over the P51's drag testing.  Seems there a bunch of calculated Cd's and even a tested Cd or two running around that are wrong.  Apparently they tested it without adding things like the exhaust stacks to the test A/C in the tunnel.  Nevertheless it does have an extremely low Cd.

P51 was an excellent fighter.

Generally speaking, lower wing loaded planes have more surface and therefore more parasitic drag.  Unless of course there is a large size difference in the first place between the planes.

Since pulling a tight bank will cause and increase in speed or force the pilot use excess speed to pay for the altitude you maintain the plane with the highest parasitic drag will bleed the most energy due to drag.

Yes Low-wing loaded planes can turn the same angle as a high wing loaded plane and pay less for it.  However when turning at their max turn rate it they pay the price like every other wing.  

http://www.av8n.com/how/htm/aoastab.html#fig-spiral-start

In order to produce 4 tons of lift, the airplane must fly at roughly 200 knots --- twice the wings-level trim speed.

Crumpp