Aces High Bulletin Board

General Forums => Aircraft and Vehicles => Topic started by: garrido on November 22, 2001, 03:50:00 AM

Title: the Drag Coefficient
Post by: garrido on November 22, 2001, 03:50:00 AM

Hello friends:

Somebody knows or has exact data on the Drag Coefficient (Frontal, eave, total) of the BF109 G6, G10, Spitfire IXF, LF, HF and Spitfire XIV variants?

 Or any Web site of where to look for them?

 Greetings

 Supongo

Title: the Drag Coefficient
Post by: wells on November 22, 2001, 07:33:00 PM

There was an article done by David Lednicer in the January '99 issue of Sport Aviation where the Spit IX, P-51B/D and Fw-190A/D were analyzed used a piece of high powered CFD  software called VSAero.  The results were:

Spit IX has wetted area of 831.2 sq ft and a CD of 0.0065

P-51B:  874.0 sq ft, CD = 0.0053
P-51D:  882.2 sq ft, CD = 0.0053
Fw-190A8:  735.0 sq ft, CD = 0.0071
Fw-190D9:  761.6 sq ft, CD = 0.0063

You might also try:
 http://naca.larc.nasa.gov/reports/1948/naca-report-916/ (http://naca.larc.nasa.gov/reports/1948/naca-report-916/)

Title: the Drag Coefficient
Post by: vector at work on November 23, 2001, 12:07:00 AM

Hi
Sorry for "offtopic", but wells as you're here, could you please tell from where to get info of converting IAS to TAS in different altitudes. Table or formula?
Thx!

Title: the Drag Coefficient
Post by: wells on November 23, 2001, 12:39:00 AM

TAS = EAS * 1/sqrt(relative density)

For the purposes of sim calcs, EAS = IAS.  In real life, you apply a position correction (calibration) to the IAS to get CAS (calibrated airspeed).  Then you apply compressibility correction to get EAS (equivalent airspeed).  Go here for a standard atmosphere calculator...
 http://aero.stanford.edu/StdAtm.html (http://aero.stanford.edu/StdAtm.html)

Title: the Drag Coefficient
Post by: garrido on November 23, 2001, 04:44:00 AM

THX Wells, but, of 109 and spit?

Grettings

Supongo

Title: the Drag Coefficient
Post by: niklas on November 23, 2001, 05:56:00 AM

I can´t offer you drag coefficients here, but i want to say that:

a) usually aircraft with lower wingloading have better CD
b) drag assumptions are only as good as their input parameters.

I like the following page: http://www.hq.nasa.gov/office/pao/History/SP-468/ch5-2.htm (http://www.hq.nasa.gov/office/pao/History/SP-468/ch5-2.htm)

In the middle, you can see how much Cd can vary with different aircraft configurations (the whole report is a good read btw).
So when you compare CD - values, you should be sure that they were all done with aircrafts in similar conditions.

niklas