climb rate and top end speed

[pimpjoe]

i dont really know much about planes except for speed and climb rates. and dont really know much about that except for the planes that we have in AH. my question is, what kept planes like the 109 that had the almost rocket powered climb from being as fast as thier counterpart, the mustang, and vice versa? to me it seems that, exept the yak, all the planes that have a good ROC seem to be slower than the ones without that good climb rate.

[GRUNHERZ]

Drag.

[MANDOBLE]

What GRUNHERZ said.

At low speeds, the drag will be overcompensated by the G10 engine and you will have a much better acceleration than P51. As speed increases, drag becomes more and more noticeable til the point that your engine does not output enough power to keep a possitive acceleration. At this point u have reached your top speed for a determinate air density.

In a substained climb at low speed, drag is minimal compared with your engine power, so, power/weight ratio will be the more important factor and the G10 will outclimb easily a P51D.

Things are very different for zoom climbs where the initial climbing speed is well above 200 mph, here the winner will be the Mustang.

[F4UDOA]

Here is an answer as best my feeble mind can explain it.

Drag. No, not men dressed as women. I mean the brick wall of Aerodynamic drag.

One reason A/C that climb well don't have a great top end is this. Their are two factors that make an A/C a good climber.

1. Power to weight.
A/C like the 109 have exceptional powerr to weight ratio's making them very good climbers. P to W ratio is the single best indicator of climb rate.

2. The lift of the wing vrs the drag of the wing.
A 109 may have a good wing for climb, ie generate high lift at high AOA however lift has a byproduct called lift drag or induced drag. So while this may cause an A/C to go up fast it may also slow it down at high speed. The cure for induced drag is two things.

a. High aspect ratio. In other words like a P-38 a very long wingspan with a thin wing Chord or width. This reduces induced drag greatly while maintaining lift.

b. An elliptical wing like the Spit. The wing shape reduces induced drag but also reduces lift, helping in E-retention through turns and giving it a very evn docile stall. The trade is relatively low lift generating wing.

To get an idea of what the total drag of an A/C is just look at top speed at sea level vrs Horspower. Like an F4U, P-47 and F6F. All have almost the same HP and almost the same weight and wing area. However the F4U has less drag because of a smaller cowl opening and angled wing roots. Hence the higher top speed.

Later

[Vermillion]

Also realize that acceleration, dive acceleration, max level speed, Sea Level max speed and maximum dive speed are all different things as well.

For instance the G10 is the fastest non-perk plane in the game. So in your example one of the fastest climbers (if not the fastest, I can't remember exactly), IS one of the fastest planes.

[FLS]

It's interesting to compare the performance differences of the Spitfire and Mustang with essentially the same engine. Not only is the Mustang faster but it got more miles per gallon. Of course it held more fuel too.  The smaller tank in the Spitfire keeps it lighter with 100% fuel which is great for climbing and turning but gives it less endurance. The Spitfire was originally a lighweight racing design but the wing has a lot more drag than the Mustang with it's laminar flow wing design.  As F4UDOA mentioned, the lift to drag ratios of the wings makes a significant difference. You don't want to turnfight a Spitfire in a Mustang and you don't want to chase a Mustang in a Spitfire.

Increasing power or reducing weight will  increase climb rate while level speed is drag limited.  Reducing drag with the same power will increase level speed and fuel efficiency. You can demonstrate this to yourself in any aircraft by adding drag with flaps or gear or adding weight with fuel or stores.

The wing design, total drag, and engine design also determine the altitude where an aircraft has it's fastest level speeds. As the air density decreases so does the drag which is why you see a difference between indicated and true airspeed as you climb. All aircraft fly faster as they fly higher until the thinner air reduces the power output of the engine. Since aircraft have different combinations of engines, with and without turbo and super chargers, with different wing designs and different amounts of drag, they have their maximum speeds at different altitudes. Their true airspeed is slower above and below that altitude. That's why maximum level airspeeds are often given along with the altitude where that speed is achieved.

--)-FLS----
Musketeers