Originally posted by killnu
WW...understand what you posted...but who just chops throttle and flies straight and level? most times I have a spit16 dive on my K4, its chop throttle and cross control in a vertical turn...they usually fly right on by as they chopped throttle to late...if at all.
I understand. But if it were the Spitfire in front and he chopped throttle first, the 109 would be more prone to blowing by than if the roles were as you stated. The tendency for an aircraft to bleed off speed is naturally exacerbated by induced drag. Knowing the baseline gives a clue as to what to expect at the minimum.
Full power speed bleed is also valuable data if you are being pursued. For example, from a post where a player complained about not being able to chase down a P-51D with his 109K-4. Here's an example of why full power speed bleed data is useful to a pilot. Here's why the 109K-4 could not catch the Mustang.
Max speed at sea level, 25% fuel, full magazines.
P-51D: 367 mph
109K-4: 368 mph
Now, let's look at variations in load out. You are flying fully armed 109K-4 with about 50% of internal fuel remaining. You run into a P-51D with 25% fuel and only 1/3 of his ammo remaining. He elects to avoid an engagement. He dives for the deck with you chasing. You both level off at abut 50 feet doing around 450 mph.
You will never catch him until long after he runs out of WEP.
Why? Simple really, a P-51D with 25% gas and 1/3 ammo can maintain 368 mph, and with a little less gas or ammo and it'll do 369 mph. Reducing weight reduces induced drag, reducing induced drag increases speed.
Another factor: The P-51D retains speed better than the 109K-4. Again, this has been tested and verified. Due to its greater mass and lower total drag, the P-51D will bleed down from 450 mph to 368 mph considerably slower than the lighter, draggier 109K-4. What this means is that in between 450 mph and 368 mph, the Mustang will actually be pulling away from the 109 because the 109 is bleeding off speed faster.
Here's actual test data....
Fuel load 25%, zero fuel burn. Full magazines. Time to bleed speed from 450 TAS down to 368 mph TAS at 50 feet ASL. Time recorded in Minutes:Seconds.tenths of seconds.
P-51D: 3:25.85
109K-4: 2:20.10
When the 109K-4 has slowed to its max sustainable speed, the P-51D is still doing 376 mph...Pulling away. After 3 minutes, 25 seconds speeds are equalized, but the gap is considerably wider and will not even begin to close for another 65 seconds (when the P-51 runs out of WEP).
I don't know if the person who was complaining understood the exercise, but knowing how well your aircraft bleeds of E, either at pull power or at idle adds to one's understanding of what the plane is capable of. As most of us realize, the more you understand your aircraft, the more likely it is that you can utilize its full performance. Thus, I test everything!
My regards,
Widewing
