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PostPosted: Thu Feb 10, 2011 7:48 am 
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that's really strange..how much bank do you need with full rudder to keep the direction?


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PostPosted: Thu Feb 10, 2011 8:40 am 
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Killratio wrote:
Now THAT is strange...the A2A bird sideslips very nicely on my setup?

Darryl

Ooooh ... lovely ... another thing for me to try out! Watch this space! ;)

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PostPosted: Thu Feb 10, 2011 9:32 am 
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bstolle wrote:
that's really strange..how much bank do you need with full rudder to keep the direction?


I have the controls all calibrated under FSUIPC and the physical travel of them is based on the real Spitfire down to the degree. (physically set up in the Simulator).

I use around 45 deg of bank, with a quick and full deflection of the controls to put her there. Years of flying almost exclusively aerobatics makes me quite aggressive with the controls. Depending on the speed (lower the better) she will "fly " herself out of it after a while sometimes but a quick realign drops her back in. The key seems to be to have a reasonably high descent rate to start and to pull the nose up and around to enter. Best at very low power settings.

Sometimes she will wallow a bit but again after a while, a quick level and realign then back in fixes it.

One of my favourite tricks is to sideslip all the way in to about 50 feet then kick out and into a three point attitude. She does that well IF you get it set up just right.


Just a thought...and please feel free to put it under the heading of the "bleedin' bloody obvious" but you don't have autorudder ticked?




Darryl

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PostPosted: Thu Feb 10, 2011 9:36 am 
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Sorry for the imprecise intial post.
I do mean a stable slip. Yanking and forcing her into a slip is no problem, but keeping it stable is impossible.
Makes only sense at idle power anyway because I desperately want to loose altitude when using a slip!
After a few seconds even with e.g. full right rudder, even the slightest amount of left bank will make her turn left.

>The key seems to be to have a reasonably high descent rate to start and to pull the nose up and around to enter

I do it exactly the other way round IRL. Because I NEED a high ROD I first enter the (crosscontrolled) slip.
Thereafter I lower the nose to avoid loosing speed.and to increase the ROD


Last edited by bstolle on Thu Feb 10, 2011 9:42 am, edited 1 time in total.

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PostPosted: Thu Feb 10, 2011 9:41 am 
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Yes, it does take some work to keep her in the slip...but that has always been a problem with FSX. The real air bird slipped but the procedure you had to use to get her in there was decidedly non standard from memory.

I once slipped a Tiger Moth all the way to the ground (excet for 20feet or so) but that did take some effort to keep her in to. The Spitfire doesn't feel quite "right" but it does feel "acceptable" to me.

A 172, of course, falls out of a slip pretty easily too. Now an Extra.... :twisted:


Darryl

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PostPosted: Thu Feb 10, 2011 9:42 am 
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bstolle wrote:
I do it exactly the other way round IRL. Because I NEED a high ROD I first enter the (crosscontrolled) slip.
Thereafter I lower the nose to avoid loosing speed.and to increase the ROD



Yes, a limitation of FSX I fear.

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PostPosted: Thu Feb 10, 2011 9:44 am 
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Nope. This was a problem with fs9 but with careful FD design that's not the case anymore in FSX.


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PostPosted: Thu Feb 10, 2011 10:07 am 
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Just spent fifteen minutes trying various methods to get a normal forward slip, and can't.

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PostPosted: Thu Feb 10, 2011 10:17 am 
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I have all my aircraft calibrated via FSUIPC and generally don't mess with it too much (if it aint broke ... etc.).

I just ran a couple of tests - one at 200mph and one at 150mph - flying straight and level. In both cases, the Spit swung instantly to one side by around 15 degrees and the airspeed instantly dropped by around 10mph (then stabilised). I also got some very reassuring wind sounds (nice touch!!).

I had no trouble at all keeping it steady with a bit of aileron. It *feels* about right ... but then most of my "real" flying has only been in gliders :lol: (some with open cockpits, where you *felt* that sideslip on your face!).

No - I couldn't persuade the Spit to do some fantastic 360 degree flat turn with the rudder ... but could they have done that in reality?

I appreciate it's not one of FSX's strong points - my C-172 crabs all over the place - but the A2A Spitfire seems well behaved, IMHO.

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PostPosted: Thu Feb 10, 2011 12:01 pm 
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bstolle wrote:
Nope. This was a problem with fs9 but with careful FD design that's not the case anymore in FSX.


During the FSX Beta, I spotted a flaw in rudder behavior that was skewing the flight models of several of the default aircraft. It involved a reversal in the yaw/roll coupling behavior as pure yaw was applied. The flaw was fixed in the last Beta number before the release candidate. The issue was a lack of complimentary roll coupling.

When pure yaw is applied, regardless of any existing dihedral effect which of course acts as a reversing force to divergence, the outside wing must travel faster than the inside wing in reacting to the yaw input. This of course increases the lift vector on the outside wing and raises that wing. This in turn causes bank and bank then splits the lift vector into twin components causing turn in the direction of the bank. This constitutes complementary yaw/roll coupling and should produce turn.

This wasn't happening in the FSX Beta FM due to a reversal between a negative and positive sign in the base FM coding. It was corrected so that the expected coupling behavior was correct at release.

This being said, I'm finding the Spit slip behavior fairly good actually. In performing slips to both sides using flaps and no flaps, I'm getting basically what I would expect in the actual aircraft. It's not perfect mind you, but acceptable on the realism level.
I would add that the Spit's rudder area simply won't handle a full rudder slip past a fairly shallow bank angle.
WW2 era fighters slip fairly flat with slight bank and opposing rudder doing the job nicely. You of course control
airspeed with pitch the same way you do in any other airplane.

You are correct that the rudder behavior on the Spit needs to be tweaked a bit. This has been addressed and the tweaked behavior will show as a change in the FM in a forthcoming patch.

Dudley Henriques


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PostPosted: Thu Feb 10, 2011 12:23 pm 
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Thanx a lot for your extensive explanation, especially concerning the shallow slip angle.

Best regards

Bernt


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PostPosted: Wed Feb 23, 2011 12:26 am 
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Hello,

I build and fly remote control planes, most are built from kits but I scratch build as well, what I noticed is that a low wing plane likes to stay flat when using rudder only in a turn but there is alot of things that can change this like adding more dihedral to the wings will give a low wing plane a better roll effect with rudder only. With a high wing plane the rudder can be fairly small and give a good roll effect with rudder only, but again depending on the dihedral in the wing. The extra is a point and fly plane, meaning because of the no dihedral and mid fuse location of the wing the plane will do whatever you tell it to rudder only will produse a fairly flat yaw effect untill one wing is flying more than the other, then things change. I'm no expert but I think the flight model is pretty acurate, and if another plane looks like the spit doesn't mean it will fly the same at all, as there is many things that come into play like the center of gravity that the plane flys at, you could take an identical plane with different CG's and they will fly differently. We use a dive test to see if the CG is close, you put the plane in a fourty five deg. dive and if the plane pulls out of the dive quickly by itself then the plane is too stable so the CG is too far forward, if it dives deeper into the dive then it is unstable and the CG is too far aft, if it maintains the fourty five deg. dive then the CG is good or very close, so there is alot of things that can make alot of change. I just wanted to share a little about the differences that I know that can effect how a plane flies, and how the rudder alone is different from plane to plane, there is so much more effecting the forces that this thread would never end and many people would have alot of input. Then there's the air file that get programmed........ :o

Have fun, Rockitglider 8)

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PostPosted: Thu Feb 24, 2011 2:22 am 
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Rockitglider,

I remember that R/C dive test for C.G. Unfortunately, it doesn’t inform as to whether the C.G. or the longitudinal dihedral, or both, want adjustment; as either or both may produce the same observed results. Also, as I know that you know, the aeroplane must be trimmed for hands-off level flight at a specific power setting before commencing the test dive. For a number of reasons, I don’t think that this test works for full-sized aircraft.

With regard to the Spitfire’s ability, or lack of it, to easily do forward or side slips, etc., no less a Spit expert than the then recently-appointed RNVR Lieutenant- Commander, FAA, Jeffrey Quill, in his 24 February 1944 report to Fifth Sea Lord, Rear-Admiral D.W. Boyd, who was investigating reports of accidents and pilot’s problems flying mostly Seafire L Mk IIC’s (RN adaptation of the Spitfire Mk Vc) onto RN aircraft carriers Attacker, Battler, Stalker, Hunter, and Unicorn, during Operation Avalanche (the Allied invasion of Salerno, Italy, 9 September 1943) in which 42 of 106 aircraft were written off due to deck- landing accidents; wrote in part:

“(1) Pilots had to be trained to employ a curved approach to the deck as the crabbed approach was acceptable only for skilled and experienced pilots:”

“Wings of the Navy, Flying Allied Carrier Aircraft of World War Two” p.133
Capt. Eric Brown

Apparently, the real-world Spit doesn’t like to be slipped very far any more than our A2A Spit does. We may have gotten it right after all. Of course, we never stop tweaking and fussing and… (sigh).

Mitchell


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PostPosted: Thu Feb 24, 2011 12:42 pm 
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Mitchell wrote:
Rockitglider,

I remember that R/C dive test for C.G. Unfortunately, it doesn’t inform as to whether the C.G. or the longitudinal dihedral, or both, want adjustment; as either or both may produce the same observed results. Also, as I know that you know, the aeroplane must be trimmed for hands-off level flight at a specific power setting before commencing the test dive. For a number of reasons, I don’t think that this test works for full-sized aircraft.

With regard to the Spitfire’s ability, or lack of it, to easily do forward or side slips, etc., no less a Spit expert than the then recently-appointed RNVR Lieutenant- Commander, FAA, Jeffrey Quill, in his 24 February 1944 report to Fifth Sea Lord, Rear-Admiral D.W. Boyd, who was investigating reports of accidents and pilot’s problems flying mostly Seafire L Mk IIC’s (RN adaptation of the Spitfire Mk Vc) onto RN aircraft carriers Attacker, Battler, Stalker, Hunter, and Unicorn, during Operation Avalanche (the Allied invasion of Salerno, Italy, 9 September 1943) in which 42 of 106 aircraft were written off due to deck- landing accidents; wrote in part:

“(1) Pilots had to be trained to employ a curved approach to the deck as the crabbed approach was acceptable only for skilled and experienced pilots:”

“Wings of the Navy, Flying Allied Carrier Aircraft of World War Two” p.133
Capt. Eric Brown

Apparently, the real-world Spit doesn’t like to be slipped very far any more than our A2A Spit does. We may have gotten it right after all. Of course, we never stop tweaking and fussing and… (sigh).

Mitchell


The question of sideslip in these prop fighters has come up many times during my association with them.
The Mustang for example was noted during testing by North American to have issues with sustained side slip due to lack of aileron effectiveness to maintain the slip angle. This was true for the 51 and ended up being so noted in the Dash 1.
What wasn't noted however was that with the power and airspeed back as is the situation in the pattern for example, the Mustang can be slipped effectively by "scrubbing off" altitude cross controlled. I've done this many times myself. In the 51, with the barn doors hanging off the training edges as they do, you don't really need all that much slip in a curving close in approach, but you can certainly perform a rudder lagging aileron leading descending base to final turn if you want to scrub off some excess altitude on final.
All in all, I would totally agree with North American on the SUSTAINED sideslip notation and I would only recommend cross controlling these fighters in the pattern to pilots having more than the average association with their handling qualities.
Both the Spitfire and the Mustang have more than adequate flap available to control the approach profile without having to slip them, but it's notable to make the fine point distinction between sustained sideslip and a TEMPORARY normal slip condition being available if required.
This subject has come up during my career often enough that I mention it as part of my familiarization discussions with pilots flying the real world aircraft.
Dudley Henriques


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PostPosted: Sat Feb 26, 2011 1:13 pm 
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A bit off topic, but this Spitfire does an inverted pass through a narrowly open door at Edwards AFB, nice made video..

http://www.youtube.com/watch?v=F3qXTq2uMz0

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