Quote:
Originally Posted by Crumpp
Look at what the aircraft are placarded for in terms of dive speeds.
In the case of the FW-190 vs P 47, the FW-190 is limited to ~466mph at low altitude while the P47 is limited to 500 mph at low altitude.
In a dive to Vne, the P47 will always gain ~34mph over the Focke Wulf FW-190A.
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I am a little disappointed that we havn't known each other's opinion after many posts.
Crumpp, P47 Vne=500mph, Fw190's Vne=466mph, the difference is 34mph, so if both of them dive steeply and pull to level flight at Vne speed, P47 is always 34mph faster than fw190. That' very simple, all of us know it. However, that is "terminal speed difference", not dive acceleration difference.
Although X plane's Vne is more than Y plane's, it is possible that X is outdived by Y WITHIN Y's Vne speed. The test in Italy 1943 between P47D an Fw190G is very useful to demonstrate this.
Quote:
(C)
(1) 10000 feet to 3000 feet, starting at 250 m.p.h., diving at angle of 65 degree with constant throttle setting. The FW-190 pulled away rapidly at the beginning but the P-47 passed it at 3000 ft with a much greater speed and had a decidedly better angle of pull out.
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That is my explanation:
g=9.8 m/s^2=32.2 ft/s^2
When both Fw190G and P47 dive in 65 degree angle, their acceleration along path(65 degree) is calculated in this formular:
Acceleration=g*sin(65)+g*(thrust/weight)-air braking force/weight
Fw190A has better thrust/weight, P47 has less braking force/weight, but at low speed, fw190's advantage is more profound, so P47 was outdived by fw190g INITIALLY, although P47's Vne (500mph)higher than fw190(466mph). This perfectly demonstrates that terminal speed and dive acceleration are totally two different concepts.
In later dive period, P47 passed fw190, both arrived 3000ft but P47 has much greater speed.Both speeds of them are well BELOW 466mph. Furthermore, P47 got higher speed BEFORE reaching 3000ft, isn't it? Don't forget fw190 was ahead of P47 after initial dive.
For example, when fw190 reached 8000ft altitude, P47 was at 8500 ft, so P47 was outdived by fw190 initially.On what altitude did P47 get same speed as fw190? Perpahps at 5000ft, at that time, fw190 was still ahead of P47, so fw190 probably at 4500ft. BEFORE P47 got same speed as fw190, P47's acceleration was better than fw190, otherwise, how could P47 get same speed? Don't forget P47 was slower than fw190 after initial dive. So P47 time line is below:
Altitude
@8500ft, was slower and after fw190
@6500ft, began to get higher acceleration than fw190, but still slower than fw190
@5000ft, get same speed as fw190, but still after fw190
@4000ft, faster than fw190, but still after fw190
@3000ft, passed fw190 with higher speed and higher acceleration.
At this time, both P47 and Fw190 speed are BELOW 466mph.
@1000ft(if don't pull to level), ahead of fw190, faster than fw190, higher acceleration than fw190 and the distance between them are enlargening.
@-5000ft(deep valley! Air density =SL), P47 still has a little acceleration, while fw190 reaches equilibium point at 1200km/h (if firm enough). Distance between them is big.
@-7000ft (deeper valley, air density=SL), p47 reaches equilirium point with 1400km/h(if firm enough)and fw190 is still 1200km/h, distance between them is bigger.
@-10000ft(deepest valley,air density=SL), p47 is still 1400km/h, fw190 is still 1200km/h, distance between them is even bigger and increasing for ever.
if @1000ft level flight(pull his stick to avoid loss), ahead of fw190, faster than fw190, and LOWER SLOW DOWN RATE than fw190, distance between them are enlargening.
The most interesting is the level flight out of envelop, above Vmax. When both P47 and Fw190 fly at Vmax at sea level, P47's 7ton weight couldn't himself at all, and P47 has a bigger wing area while same 2000HP engine with fw190, so P47's Vmax is less than fw190.
But if both of them level fly above Vmax, the 7 tons weight helps P47 a lot because the heavier, the more ability to retain high speed above Vmax.
Acceleration=g*(thrust/weight)-air braking force/weight
Acceleration is always negative when you are slow down from 800km/h to 600km/h on the deck, and it usually takes a whole minute/60 seconds to slow down to 600km/h(Vmax).
Thus if P47's big 4-blade propeller efficiency is 20% higher than fw190's small 3-blade at the speed range from 680 to 800km/h IAS(out of envelop), fw190 will suffer a lot of ENERGY BLEEDING.
We all know bf109k4 has a excellent climb rate over La7, it usually takes k4 a whole minute to establish 500 m altitude advantage if both have same energy in the beginning. P47/P51/Tempest could also establish 500 m higher altitude if they use high speed boom and zoom tactics-----their own method! AS EFFECTIVE AS BF109K4.
It is obvious for all il2 players if 109K4' s climb rate is degraded to la7 level. People will shout:"Sh*t, where is 109K4's climb advantage? how can I do a energy fighting?" Unfortunately, if il2 neglects the propeller efficiency difference/sharp drops between various aircrafts at high speed(680-800km/h), P51P47Tempest will lose half of their energy fight tactics effect------energy-saving high speed boom and zoom, and not many players will notice it, many players don't know that P51P47Tempest are tigers WITHOUT teeth in il2. The teeth had been taken by someone who, for some reason, didn't pay enough attention to high Mach number/compressibility effect which leads to efficiency decrease of a CSP.