Author Topic: spit 14 (Read 825 times)

Naudet · « **Reply #15 on:** March 31, 2002, 04:47:05 AM »

One question about torque effects on turning.

How exactly does this influence turning?

Arcon · « **Reply #16 on:** March 31, 2002, 05:02:55 AM »

The spit XIV had a 5 bladed prop. Had to use something to absorb the HP from the bigger engine.

Yaw or rudder torque, commonly associtaed with taking off, was caused by a slipstream that would impact the rudder on one side but not the other. Big bladed props caused this more than anything else, other than too small a rudder/vert stab.

When the Spit XIV slows down, it has two probs:

The extra weight of the higher HP engine AND the added/combined effects of higher slipstream torque, plus the normal torque effect of the engine.

Therefore: much more snappy

But not if you turn the engine down!

Try it! Try the same tests with engines turned down somewhat.

The Double Torque effect really hurts it.

.02

Vermillion · « **Reply #17 on:** March 31, 2002, 07:29:19 AM »

I thought the Griffon rotated opposite from the Merlin?

If it rotates the same direction, then your correct and its too the left.

Vermillion · « **Reply #18 on:** March 31, 2002, 08:11:36 AM »

This started to bug me, and it would kill me to be wrong on something as simple as this

From "World Enclyclopedia of Aero Engines", by Bill Guston

-------------------

The Griffon had cyclinders of Buzzard/R size (6x6.6 in, 2,239 cubic inches) and started off with a lot of Merlin experience built in; yet for most of the war Lovesey managed to keep the Merlin ahead, especially at altitude. The Griffon never equalled the Merlins specific output, but was nevertheless a fine engine, which transformed the Spitfire and Seafire (not least in rotating in the opposite direction, which reversed take-off procedures, though this attribute disappeared with contraprops which were common on the Griffon). Later marks gave around 2,000hp up to at least 20,000ft, maximum power being 2,540hp though in some racers........

-----------------------

Realize that aircraft turn best in the direction that the torque of the engine pulls them. Because if they're turning in the opposite direction at very low airspeeds (ie near stall speed) the torque of the engine can flip the aircraft over and cause a stall.

Now go into the arena offline and do this simple test. Turn off auto takeoff and combat trim. (I just did this btw)

Load up a Spit IX, start the engine and don't touch the rudder pedals. You will veer to the left. Spit IX's (and all Merlin Spits) turn the best to the left.

Load up a Spit XIV, and repeat the test. You will veer to the right. Spit XIV's will turn the best to the right.

This can also be tested by doing consecutive 360 degree turn tests (no altitude gained or lost) in each direction with a stop watch and average the time results for each direction. But I didn't feel like spending an hour on something when I know what the results will be anyway

Seriously, if it doesn't work that way, something is really wrong with the Spit XIV fm.

I've been out of town this past week and today was the first chance I'd had to fly the XIV. All I can say is "WOW!", and boy am I glad this plane is perked. It would quickly become "Spitfire High" otherwise (hell it almost is already

). It turns as well as a Spit IX, builds energy like a bat on fire, and I didn't notice anymore adverse torque effects or high speed handling problems. Fly this plane like a E fighter, and there's nothing in the arena that can touch it 1 v 1. Not the Tempest, not the F4U-4, and none of the nonperk planes. The only problem you could possibly have with it, is if you get right down on the deck being chased by multiple La7's and you just let them run you down. If its just one or two, you can turn fight them and win easily. But then again, I'd just make sure I stay above 5k where the Spit can outrun them

MiloMorai · « **Reply #19 on:** March 31, 2002, 08:37:44 AM »

Looking from the cockpit the Griffon rotated CCW, the Merlin CW. The Griffon weighed ~300lb more than the Merlin.

The Giffon put out ~4700lb-ft of torque.

A net search will turn up many sites for both engines.

J_A_B · « **Reply #20 on:** March 31, 2002, 01:02:44 PM »

Hmm, Verm is right about how they behave in AH....

With planes like the Spit 9 or P-51, if you're taking off or in flight the torque will cause the aircraft to roll left.......yet the propeller itself spins to the right...

What I want to know is why. If a plane's propeller is rotating right (clockwise), why should it cause a plane to turn LEFT. This was not what happened with R/C airplanes I've built--they always wanted to go in the direction that the prop was spinning, not the opposite.

In addition, as Karnak's real-world comparison's show, the aircraft supposedly performed as one would expect them to; that is, the Spit 9 turned better to the right and the Spit 14 turned better to the left.

Something wierd seems to be going on. Anyone care to try to figure it out?

J_A_B

Karnak · « **Reply #21 on:** March 31, 2002, 02:30:39 PM »

Verm,

I don't know which way it should turn better, only that in reality the RAF concluded that it turned better to the left.

Yes, it is a monster and I would fear no other aircraft in AH in one. The problem is that it always, like all perk planes, gets gangbanged. This if fine if they're below you, you can keep them below you at all times. It isn't fine when they show up above you. At that point you can't use you're climbing ability to get out and unlike the Tempest or 262 you can't dive away either, you're just not fast enough. The F4U-4 and Ta152H-1 share this problem.

SFRT - Frenchy · « **Reply #22 on:** March 31, 2002, 02:37:08 PM »

Quote

Originally posted by J_A_B
will cause the aircraft to roll left.......yet the propeller itself spins to the right...

What I want to know is why. If a plane's propeller is rotating right (clockwise), why should it cause a plane to turn LEFT.
J_A_B

It's because to turn to the right, the prop axel needs to hold itself to something. It's like if you put on a pair of rollers and help yourself to move foward by pushing on the wall. If you do the same thing but the wall is on wheels too, the wall will move backward and you foward.
This "backward movement" translates on the plane as an opposite rolling tendancy that you need to counter with your controls.

Torque is not the only think who makes the airplane want to roll, u have stuff like Pfactor, gyroscopic forces and the spiraling slip stream.

Naudet · « **Reply #23 on:** March 31, 2002, 03:54:16 PM »

Quote

At that point you can't use you're climbing ability to get out and unlike the Tempest or 262 you can't dive away either, you're just not fast enough.

I yet didnt fly the XIV, but Karnak i dont believe that, i did a comparative divetest once between tiffie, spit IX and FW190D9.
Both RAF fighter never compressed - even after near vertical dive from 20k - nor did they show any stress or control authority loss.

If the XIV shows the same diving chracteristics in AH like the IX, you can just push the nose down, let urself get to 500+ IAS and run away without any compression or control authority loss.

Edit: I did a quick XIV dive test, and i managed to compress it. It started at about 440 IAS at 15k and at 10k it will shake till speed falls under 505 IAS. With those speeds and the accel shown in the dive, the Spit XIV will be one tough plane to catch.

Karnak · « **Reply #24 on:** March 31, 2002, 05:47:49 PM »

Naudet,

I was speaking to the realities of the AH MA, where you will not be diving from 20,000ft to escape. If you are at 20,000ft, you're not in a fight and don't need to dive.

In AH you'll have maybe 5,000-10,000ft below you. The Spit XIV can dive extremely rapidly and will escape from most aircraft that way, then it has to level out and many aircraft (La-7, P-51D, P-51B, Typhoon, Fw190D-9 and Bf109G-10 {Yak-9U?, La-5FN?}) will run it down because they are faster in sustained fights.

If the fighter in question is diving from a significantly higher altitude even the great diving ability of a Tempest won't get you out of danger.

bozon · « **Reply #25 on:** March 31, 2002, 07:53:59 PM »

just tried the 14 first time.
I was chased by several planes at low alt (ground was 4k) among them a 190 whom i belive was a D9 (cant be sure though). the dora closed till d800 co-alt while I was in a shallow climb 1kFTS wep on. at those conditions it couldn't catch up.

Bozon

Vermillion · « **Reply #26 on:** April 01, 2002, 09:19:42 AM »

They way they fly in AH is the way they fly in real life in regards to torque and the other rotational effects. I'm not sure where the report that Karnak has came from, but its opposite of the historical information I've read.

Karnak, yes you get gangbanged/Suicide chased in it just like every other perk plane. Thats just the fact of a perkie. I think you would agree that it should be perked though, or it would rapidly take over the entire arena.

If you get caught with less E by enemy follow on planes, just do what you do what any BnZ plane caught in that situation has too do. Make the enemy commit to the attack and miss, equalize the energy over several gun passes, then disengage with your superior speed and acceleration. And with the turning ability of the XIV it should be relatively easy to make them miss their first few passes.

And while its true there are a few planes faster on the deck than the XIV, you only have to keep a few thousand feet under you, and your just as fast. If you dive away, you don't have to dive all the way to the deck. Keep a hard deck of 4k to 6k and you should have no problems what so ever.

MANDOBLE · « **Reply #27 on:** April 01, 2002, 09:41:04 AM »

Karnak, the point about diving is not really the top speed once leveled, but the control at hi speeds. With a 190D9 I'm able to catch by speed a typh in a dive, but no way at all to follow its manouvers at these speeds. While the typh will make a hard turn at these speeds, the Dora will keep shaking and with almost no control at all. Same with spits.

spitfiremkv · « **Reply #28 on:** April 01, 2002, 11:57:14 AM »

just as an interesting fact- a Spitfire survived a Mach .91 dive...well,not in mint condition but still flyable. So the fact that it performs well in a dive and isn't affected by compressibility is not an overlook from the programmers of the flight model.
Once again, Spitfires rule!!!!!!!

Vector · « **Reply #29 on:** April 01, 2002, 12:21:58 PM »

Quote

Originally posted by spitfiremkv
just as an interesting fact- a Spitfire survived a Mach .91 dive...

Interesting indeed as spitfire never achieved such a speeds nor did P-51s & P-47s. Near speed of sound propellers starts to act like a speed brake.
"Despite having a propeller that was designed to be more efficient at these speeds, the fact remained that the drag rise across the prop was so great that it functioned like a giant disk shaped air brake. Fisher had proved beyond any doubt that all previous claims of exceeding the speed of sound while diving a prop driven aircraft were untrue. There is little doubt that the pilots who reported speeds in excess of Mach 1 were honestly and accurately reporting what they has seen on their air speed indicator. However, due to the extreme rate of descent, the pressure differential in the static pressure airspeed indicator lags far behind the actual altitude of the aircraft. Air speed indicators of the era were not designed to cope with descents that could exceed 40,000 feet per minute. This difference between outside pressure and that within the system would indicate wildly ambitious speeds. These pilots had simply been fooled. When we stop and consider that the ultra-sleek P-80A Shooting Star jet fighter was never able to exceed Mach .94, how can anyone believe that a prop driven fighter could even come close?[/b]

P-47 achieved mach 0.83.

Check here