Vertical Rolls In The Spitfire

[Screamadelica]

I've been trying my hand at vertical rolls in the Spitfire, not quite as easy as first thought.

I take it to the vertical with plenty of speed but as soon as left aileron is applied the left wing drops requiring a hefty push forward on the stick to try and keep the nose pointed straight up.. Bit of a wrestle and wobble at first but then it evens out nicely. Best attempt so far has been two and a half complete rolls and then out over the top and down.

Just wondering if there is anyway to avoid the left wing drop at the start to keep the roll nice and even?

Cheers, Scream.

[DD_Fenrir]

 

1 hour ago, Screamadelica said:

I've been trying my hand at vertical rolls in the Spitfire, not quite as easy as first thought.

I take it to the vertical with plenty of speed but as soon as left aileron is applied the left wing drops requiring a hefty push forward on the stick to try and keep the nose pointed straight up.. Bit of a wrestle and wobble at first but then it evens out nicely. Best attempt so far has been two and a half complete rolls and then out over the top and down.

Just wondering if there is anyway to avoid the left wing drop at the start to keep the roll nice and even?

Cheers, Scream.

 

Okay bit of minefield this but bear with me...

It's down to gyroscopic precession.

1. Full left stick deflection will result in a right yaw. Why? Adverse yaw. The down-going wing creates less lift. This creates less drag. The up-going wing is creating more lift, but ergo is creating more drag. (see Induced drag). The net result is that the aircraft will start yawing it's nose to the right.

The Spitfire has Frise ailerons that should mitigate the effects of adverse yaw but they only work up to a point - large lateral stick displacements will overpower any mitigating effect they have.

2. The right yaw, thanks to the massive gyroscope sitting right at the front of your Spitty, otherwise known as the propeller, will induce a gyroscopic procession reaction. In this case it will want to lift the nose up from your point of view.
Ultimately, to prevent the pitch up, you must prevent the adverse yaw by inputting the correct amount of left rudder in as you move the stick to keep the nose tracking dead straight as you initiate the roll. It won't be full left rudder, not a lot at all in fact but it will need some.

[kablamoman]

6 hours ago, DD_Fenrir said:

The right yaw, thanks to the massive gyroscope sitting right at the front of your Spitty, otherwise known as the propeller, will induce a gyroscopic procession reaction. In this case it will want to lift the nose up from your point of view.

Not sure what’s up with OP’s question, but just to alleviate any potential for confusion:  As far as gyroscopic procession is concerned, yaw to the right would contribute to a nose-down moment with a clockwise turning prop.

[DD_Fenrir]

Crikey, yes Kab you’re right.

I was thinking because nose down gives a left force (i.e. on takeoff when you lift the tail), than the opposite is true and you simply reverse but it isn’t that simple is it?

Just remembered the right hand rule and realised I have it backward.

In which case scream I have no idea what is causing your problem. 

I’ll give it a try myself and see if I can replicate, otherwise can you post a video showing what’s happening?

 

 

Edited December 12, 2023 by DD_Fenrir

[Screamadelica]

Thanks DD.

I understand the basics of gyroscopic procession, had a feeling that it might possibly be involved in some way.

I guess my question really is what is the correct sequence of control inputs for performing a vertical roll in the Spit without dropping the left wing at the start?

All the references I've been able to find, British Aerobatics Academy and similar, simply say keep her straight up and then apply full left or right aileron.

I always use a little forward stick to keep the nose straight in the vertical as well as a small amount of right rudder to keep the wings level.

Maybe it just needs a good kick of right rudder at the same time as you give it left aileron input?

I'll try and record a track on the weekend and post the results of my embarrassing attempts at piloting if I can.

Scream.

 

[DD_Fenrir]

One thing to bear in mind is that as the Spit slows with power on the nose will lift; it comes with the Spitty's marginal longitudinal stability. Your stick therefore will have to move forward as the airspeed bleeds to hold your attitude.

[Toastfrenzy]

Hmm, I'll see if the same happens, not that I've ever attempted a vertical roll before 

 

Edited December 14, 2023 by Toastfrenzy

[Screamadelica]

Problem solved.

DD Fenrir was on the right track. 

Giving the rudder a good push to the right as you give it full left aileron and then easing off as the roll progresses stops the left wing dropping.

Spitfire now resembles a slightly wobbly spinning top. Fun times.

Keeping her perfectly straight up as she rolls is a bit of a challenge.

Time for some more Christmas carnage......

[Toastfrenzy]

Just a question, is it ever advantageous to use cross controls? In your case yes, but is this a sim issue or an effects issue?

For instance, I was taught, to stop the nose from rising when you roll left, lead with the left rudder so the adverse effects of roll (yaw), is negated by the rudder input.

If any plane you fly the nose raises up and opposite to the direction of roll then you need a bit of lead rudder, in direction of turn to stop.

Edited December 20, 2023 by Toastfrenzy