Crumpp

The Dora holds it own against the P-51 in the angle fight, IMHO especially if you lag pursuit. It beats the P-51 in level speed and climb in the low altitude fight.

I tried recalibrating but for some reason in the P-51, the throttle axis just ends at ~1/4 throttle. It is annoying because I can never bring the engine to idle. It only appears in the P-51. The other DCS models are fine. :huh:

The guns you and I used were not encased in a wing and lightweight barrel like the fixed weapon installation of the P-51. If it was not a problem and did not need to be done, burst limits would not have been published. :thumbup:

Similar career paths, LOL! :thumbup:

It just amazes that this even has to be said....... Moving on... The head space and timing was set before each flight in a M2 .50 caliber equipped aircraft, even the P-51 Mustang.

I got a little time on a .50 cal too. 3000 rounds in one night is meaningless. 3000 rounds in 5 minutes is a melted barrel. Also, you got lucky if you think you were so good as to not have to use a gauge. There is a reason SMA published that article. The chart IS the burst limits for the Aerial Weapon M2 .50 caliber as used on the P-51 Mustang.

The M2...HB or Aerial M2...both suffer from the same barrel design and even use the exact same headspace and timing gauge. What is your point?? :dunno: The rate of fire you pointed out the first time has nothing to do with anything except BOTH M2 variants need cool down periods between burst's. Now your making hay over what???

First of all, the Article was written in 2008... It is talking about FUTURE development. But I have no idea why you think that is applicable to the Rate of Fire listed below. That is the sustained and rapid rate of fires for a ground based M2HB...not the Aircraft M2 Fixed. You are confusing weapons....and adding that confusion to the conversation!!! :megalol:

For running the engine in a static environment but flight conditions are not static.

It is the lack of cool down period requirement that is unrealistic.

Some words on the H&T of the .50 cal from the Sergeant Major of The United States Army http://www.army.mil/article/12332/Leaders_Book_Notes___Accidents_Involving_M2__50_Caliber_Machine_Gun/

Actually, it does have to be checked often in a .50 caliber. Not being correctly adjusted is the most common source of malfunctions. The barrel on a .50 caliber is removed at every cleaning and can be changed in the field...that is why it has a quick change barrel. http://www.armystudyguide.com/content/army_board_study_guide_topics/m2/m2-study-guide.shtml Once more, setting the headspace and timing on a .50 cal...is a basic infantry task.

You ae correct Echo38! It was industry standard and aviation convention to endurance test engines. Overboosting them made it even more critical due to the extreme stress on the engine. In all the development and testing engines, the Merlin 66 program ran 1000 hours of test stand time before they got a single engine to last 100 hours. The Rolls Royce engineers were very concerned even with that testing that it did not subject the engine to enough stress to reproduce an operational environment. That 100 hours on a test stand represents the minimum criteria for a service clearance. If you want to know how long you can run the engine at an overboosted condition without risking immediate engine failure...read the Operating Instructions! In this case, 100 hours on a test stand got you 5 minutes in an operational environment and some pretty serious cautions if you used it. It had to be reported, recorded, and the engine inspected with each use. Looking at any of the endurance testing and getting excited about how "strong" their engine is (BMW, Rolls Royce, Daimler Benz, Allison, etc..) is simply obtuse. Usually it is on a test stand with a device called a "club" instead of propeller. A club is basically a shortened propeller that provides necessary engine cooling. http://www.motoart.com/products/miscellaneous/radial-test-club-wall-art It can also have a torque stand which usually has a dynamomoter which applies torque to the shaft. No matter which method, there is a conversion depending on which method to correct the test stand data to flight conditions. Yes, actual flight is much harder on the engine.

Thank You, Jcomm! Shoot me a PM and let me know how the glider competition went!

I do not know if it is modeled but this is absolutely correct! Obviously, you have worked with the .50 cal! :thumbup: I would like to have realistic use of our guns instead of the "spray and pray" method of holding the trigger down you so often see. Notice the guns are fired in very short burst's or 2-3 seconds on the M2 Aerial Weapon. Having to use short controlled burst is a characteristics of open bolt single barrel automatic weapons and not just the .50 cal.

It is a way of saying EXACTLY what I said: The Stall Speeds are listed in Indicated Airspeed not True Airspeed. It must be converted to True Airspeed at sea level on a standard day. The position error data in the 1944 manual ends almost 100 miles per hour above the stall speed. There is no PEC curve in the 1944 manual, just data points. That leaves much to interpolated and opens up for a very large margin of error. That leaves no curve to use in picking the Stall Speed. It simply not an accurate data point for converting indicated airspeed to calibrated airspeed in the 1944 manual. It was not intended for engineers and pilots do not care about calibrated airspeed in a stall. Here is a typical Position Error Curve: Here is a good Position Error Curve on the P-51. Because of the nature of installation error, it is dependent upon angular velocity of the air impacting the pitot tube. That can induce large error in the individual data points. Notice the two oulier data points at 210 mph and 218 mph. The other data is much better and leaves nothing to interpolation therefore has a much smaller margin of error. That is why I use it.

I would like to see better stall speed data on the P-51. That is why I use the CLmax of 1.41 because it represents a more solid data point than the 1944 P-51 Operating Instructions give me.

Yo-Yo explained: Understand the first few degrees of flaps represents ~75% of the flap design lift gains for only 25% of the flaps design drag losses. That is why combat flaps are on only ~10 degrees or so.

(13110000*.000157926)/3 = 685.77fps = 467mph for the wing section = CLmax 1.75 (13110000*.000157926)/8.8 = 233fps = 159mph for the XP-51 (9030000*.000157926)/3 = 472fps = 322mph for the wing section = CLmax 1.7 (9030000*.000157926)/8.8 = 161fps = 109mph for the XP-51 (6100000*.000157926)/3 = 319fps = 217mph for the wing section = CLmax 1.65 (6100000*.000157926)/8.8 = 109fps = 75mph for the XP-51 Interestingly enough, the NACA concludes the change is ~.2 on the CLmax. 1.8-1.58 = .22 change coefficient of lift for the Focke Wulf 1.7-1.41 = .29 change in coefficient of lift for the P-51. The CLmax of 1.41 comes from the lift formula and represents the clean stall speed for a TO weight P-51D with wing racks installed. Using the 1944 Mustang POH which does not have a good PEC curve in the vicinity of Vs for the Mustang and interpolating the stall speed.... I get a clean configuration CL max of 1.53 for the Mustang and puts the analysis spot on with Yo-Yo's work. 1.7-1.53 = .17 change in coefficient of lift for the P-51 so the PEC curve maybe throwing us off somewhat and shows the analysis could be a hair optimistic. The ROT advantage for the Dora is only a one hundreth of a degree per second and the Dora cannot match the P-51's speed nor can the P51 Match the Dora's turn speeds. If either aircraft tries to fly to the others speeds, they will be outturned. There is some "wiggle room" because of the lack of good clean configuration stall speed data on the Mustang. I do not think the Mustang could ever outturn a Dora at the Dora's turn speeds. The best the Mustang can do is match the turn rate.

You are most welcome. Anytime I can help, jcomm!

Anything I can do to help, just let me know, jcomm!

It does agree with the real behavior.

A quick test reveals a marked nose up pitch when I deploy full flaps above the limitation speeds. Lowering flaps at 165mph or lower shows an almost immediate nose down pitch.

What he says is absolutely right with one exception It is not just high wing aircraft...it is a result of conventional tail and specific stability characteristics of aircraft at the time you lower flaps. (CG location, Cl, etc..)