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Author Topic: P-51D, Tempest, LA-7 Airfoil Comparisons  (Read 9258 times)

Offline Stoney

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P-51D, Tempest, LA-7 Airfoil Comparisons
« on: February 28, 2008, 07:39:37 PM »
The "P-51...Awful" thread was starting to get cluttered, so I thought I'd start a new one for this.

I've got root/tip chord data for the Pony courtesy WW.  Anyone have root/tip chord data for the Tempest and LA-7?
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Offline BaDkaRmA158Th

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #1 on: February 28, 2008, 08:26:56 PM »
Lets hope they also fix the 51's flaps and Fm with this next update.
Time will tell.
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Offline Stoney

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #2 on: February 29, 2008, 01:26:54 AM »
I'm looking for the lengths in inches or cm or meters of the root and tip chords for the Tempest and LA-7.

That's it.
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Offline Tilt

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« Reply #3 on: February 29, 2008, 06:24:30 AM »
can you scale off this?



NACA root   23016  

NACA tip      23010
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Offline Charge

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #4 on: February 29, 2008, 07:14:49 AM »
Hawker Tempest    Root: H/1414/37.5 (14%)  Tip:H/1410/37.5 (10%)

http://www.ae.uiuc.edu/m-selig/ads/aircraft.html

-C+
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Offline Stoney

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #5 on: February 29, 2008, 10:39:47 AM »
Quote
Originally posted by Tilt
can you scale off this?

NACA root   23016  

NACA tip      23010


Possibly.  Just don't let anyone give me the Red A** when I only use a close approximation :)
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Offline Stoney

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #6 on: February 29, 2008, 10:40:29 AM »
Quote
Originally posted by Charge
Hawker Tempest    Root: H/1414/37.5 (14%)  Tip:H/1410/37.5 (10%)

http://www.ae.uiuc.edu/m-selig/ads/aircraft.html

-C+


I've got all the airfoils.  Just need root chord and tip chord.
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Offline Stoney

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #7 on: February 29, 2008, 11:10:47 AM »
Quote
Originally posted by Tilt
can you scale off this?


From the drawing, I got an approximate of .84 meters at the outboard aileron edge (~tip chord) and 2.58 meters at the joint of the wing and wing fillet at the fuselage (~root chord).  Anyone have any grief with these numbers?

EDIT:  I did the measurements over again, as the best characteristic length for wing Reynolds Numbers is Mean Aerodynamic Chord.  Using my CAD, I dimensioned the drawing and came up with a MAC of 2.26 meters, given a reference root of 2.7 meters, and a reference tip of .93 meters.
« Last Edit: February 29, 2008, 12:44:49 PM by Stoney »
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Offline hubsonfire

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« Reply #8 on: February 29, 2008, 11:22:50 AM »
Not until you bother to do the math, no.
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Offline Tilt

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« Reply #9 on: February 29, 2008, 04:13:28 PM »
« Last Edit: February 29, 2008, 04:17:05 PM by Tilt »
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Offline Stoney

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« Reply #10 on: February 29, 2008, 06:27:45 PM »
Quote
Originally posted by Tilt
http://www.ajgs.com/Avaition-Protected/MACLength11ajgs.htm

or

http://www.nasascale.org/howtos/mac-calculator.htm



?


Don't know where they got their formulas, but Dr. Dan Raymer gives:

MAC = 2/3*Croot*((1+lambda+lambda)/(1+lambda))

Where:

MAC = Mean Aerodynamic Chord
Croot = Root Chord
Lambda = Taper ratio

Given that the taper ratio of the LA-7 planform is so high (~30%), it moves the MAC much closer to the root (and with a higher % of root chord) than on wings with more common taper ratios between 40-50%.  Furthermore, continuing on (although not needed for my experiment), you use the following equation to determine the length in span, from the root, at which the MAC occurs:

Y = (b/6)*[(1+2*lambda)/(1+lambda)]

Where:

Y = Distance from wing centerline outboard
b = wingspan

[Taken from Aircraft Design:  A Conceptual Approach]
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Offline gripen

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P-51D, Tempest, LA-7 Airfoil Comparisons
« Reply #11 on: March 01, 2008, 05:20:25 AM »
These are the LaGG-3 dimensions measured by the Germans. Should be pretty much the same as La-7, only minor differences in the wing root.

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Offline Tilt

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« Reply #12 on: March 01, 2008, 12:18:04 PM »
Neat gripen..........

La5FN and  La7 did not have the outer fuel tanks (but the inners were slightly bigger) and the fuselage was wider on the Radial engined Lavochkins. Other wise the wing would be identical.

never occurred to me before but I guess the split in the flaps would have been across the wing joint.
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Offline gripen

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« Reply #13 on: March 01, 2008, 04:38:04 PM »
It's from a German study on wooden structure of the LaGG-3, there is also some pictures of early La-5s. It's a large report but mostly boring material analysis, however, there is some good info on details.

At least in pictures of Finnish LaGG-3s flaps go across the wing joint but it actually has a joint at the point outer wing starts. Below is the LaGG-3 series 35  "57" after capture, later it became LG-3 in FAF.

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Offline Tilt

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« Reply #14 on: March 01, 2008, 05:00:10 PM »
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