Spit IIa

[IvanK]

So we are all reading from the same page, here are the relevant bits from both the Spit MK I and Spit MKV pilots notes. (The Spit MKII section is pretty much word for word whats in the MKV manual)

SPIT MKI



SPIT MKI ON FLICK MANOEUVRES


Warnings on the dangers of high speed flick manoeuvers but no real dramas on Lower speed flick manoeuvres, makes sense as no chance of real overstress or excedence of rolling G etc. As you can see pilots are being encouraged to experiment with these

The section in the Spit MKV manual on Stalling and Spinning.

[TomcatViP]

intersting to note for the neg G cut-out debate : in the Rolling paragraph of teh Aerobatic section : "The roll being barrelled just enough to keep the engine running throughout"

Def even with an MkV, G as to be kept positive to say the least

OOhh and pls do take attention to the cruise speed

[Crumpp]

A spin may be defined as an aggravated stall that
results in what is termed “autorotation” wherein the
airplane follows a downward corkscrew path.

http://www.alphatrainer.com/handouts.../pg_4-12-2.pdf

A spin is defined as an aggravated stall that results in autorotation with a corkscrew path downward.

http://www.mountainflying.com/Pages/...revisited.html

A spin may be defined as an aggravated stall that results in what is termed “autorotation” wherein the airplane follows a downward corkscrew path

http://www.pilotoutlook.com/airplane_flying/spin

Can you force an aircraft to spin by control input from a 1G level stalled condition?

Sure!!

What are you doing with your accelerations to the aircraft when you input those controls?

Think about it.

[Crumpp]

So we are all reading from the same page, here are the relevant bits from both the Spit MK I and Spit MKV pilots notes. (The Spit MKII section is pretty much word for word whats in the MKV manual)

Thanks for posting that.

Can you post the section on maximum turn performance recommendations from the Spitfire Mk I Operating notes so that all can read it?

I think the participants will have a better understanding of what I said earlier:

Crumpp says:
The major point being made on the stall is the engineering tradeoff for that large amount of stall warning in the form of early and hard buffeting is a reduction in turn rate before Clmax is reached.

[IvanK]

Crump you are mixing terms .... early in this discussion you introduced the term Aggravated and then picked up on Accelerated as others started to use it. Aggravated in terms of aerodynamics is not a common term. The Alpha pdf you refer to is the first time I have seen it used this way. The use of the term Accelerated with respect to stalling refers to to Stall entry at greater than 1G, to do this obviously requires higher IAS to generate the additional G at the same critical AOA. So by definition An Accelerated Stall is a stall at greater than 1G. In our Spitfire discussion where structural damage was being referred to we were describing a Spin entered from a high G accelerated stall departure with subsequent excessive G (notatably rolling G which is usually dramatically lower limit than the usual quoted symmetrical G limit)

Now as to thinking about controls and accelerations at spin entry as you suggest. A standard copybook 1G stall and spin entry has you arriving at the Critical AOA in 1G flight with close to full backstick. As the stall develops (ideally a nanofart before) you smoothly apply and hold full rudder (I guess you could say this is "aggravating" the stall ). The aircraft will then autorotate and (in most cases) if the controls are held it will stabilise in a spin. That is a classic 1G un-accelertaed stall spin entry. At the departure point you are already at max AOA (at or close to full backstick at 1G) so dont have the ability to increase G therefore the stall is un-accelerated.

Is this the section you wanted posted from the Spit I pilots notes ?


Sounds pretty standard to me, Max turn performance in a conventional straight wing aeroplane.

Turning just short of critical AOA is a pretty basic fighter pilot skill. The Stall buffet in many aeroplanes has "depth" and differences in the degree of buffet that can be felt through the stick. As the AOA is eased on the first clues is a low intensity buffet described in some circles as the "Buzz" as the AOA increases the buffet gets harsher (Buzz turns into buffet) eventually you get to critical AOA and the stall ocurrs. Embryo military pilots are taught to feel the subtle differences in the buffet. Max performance turning is done "On the Buzz". A standard exercise is to do this whilst airspeed and G are changing whilst holding the aeroplane on the Buzz throughout without reference to AOA instrumentation etc ... just by feel.

In the more modern types (FBW with active leading and trailing edge flaps etc) high AOA capabilty and aerodynamic configuration has you in a lot of buffet any time you are close to max turn performance ... typically in the 25-30 degree Alpha regime (except in the pussy low AOA limited F16 . As such AOA cueing via instrumentation or audio is there to help you get the max out of the jet though there still is a certain tactile feel to just how deep into the buffet you really are.

[SEE]

Every pilot, be they Axis or Allied attested to the Spits flying ability.
Disregarding the BoB, at the end of the Malta aircampaign the attrition rate was 1 allied loss for every 10 LW/Italian confirmed kills. Beurling (Spit Mkv) scored 3 BF109 kills and a Ju88 in one sortie with 29 Kills over the few months he was flying in that campaign - that tells me more than any data sheet!

Originally Posted by SEE

Every pilot, be they Axis or Allied attested to the Spits flying ability.
Disregarding the BoB, at the end of the Malta aircampaign the attrition rate was 1 allied loss for every 10 LW/Italian confirmed kills. Beurling (Spit Mkv) scored 3 BF109 kills and a Ju88 in one sortie with 29 Kills over the few months he was flying in that campaign - that tells me more than any data sheet!

Now THAT's the evidence we definitely needed. *giggle*

[RAF74_Winger]

Originally Posted by IvanK

Max performance turning is done "On the Buzz". A standard exercise is to do this whilst airspeed and G are changing whilst holding the aeroplane on the Buzz throughout without reference to AOA instrumentation etc ... just by feel.

I was taught to pull to the 'nibble', just a slightly different colloquialism I suspect.

The 'depth' of the buffet is due to washout I suspect, and very indicative of the progressive nature of the stall along the span. With light buffet, a very small inboard section of the wing has actually exceeded alpha max, but the remainder of the wing is at or near CLmax.

W.

[Crumpp]

Crump you are mixing terms

Nobody is mixing terms.

Aggravated in terms of aerodynamics is not a common term.

Sure it is a common term.

Simone Zuccher∗ and Sergio De Ponte†
Politecnico di Milano, 20158 Milano, Italy.
DOI: 10.2514/1.25389

The spin of an airplane occurs for angles of attack beyond stall, where nonlinear aerodynamics dominates and where complex and unpredictable behaviors might induce to question whether or not such a motion is chaotic. To find an answer to this issue, wind-tunnel tests are carried out on a model of a fighter attached by its center of gravity through an universal joint that allows only the three rotations. These degrees of freedom are analyzed according to modern techniques for the study of “supposedly chaotic data.” It is found that, for increasing Reynolds number, successive bifurcations take place with a consequent more complex structure of the attractor, which reveals some features typical of quasi-periodic systems evolving toward chaos. The model is tested also in other configurations (different nose and/or leading-edge extensions, presence or absence of tail planes) so as to verify the dependence of the motion on some details. It is found that unpredictability and strong dependence on the initial conditions characterize
the basic configuration, whereas a blunt nose and leading-edge extensions make the motion extremely regular. Even though the system might be on its route to chaos, a fully developed chaotic behavior is not observed.


Nomenclature
c = wing mean chord, m
f = frequency, Hz
k = reduced frequency, fc=U1
Re = Reynolds number, U1c=
t = time, s
U = wind-tunnel streamwise velocity, m=s
t = time interval, s
= kinematic viscosity, m2=s
= time delay
’, , = degrees of freedom (roll, pitch, and yaw), deg
Subscript
1 = asymptotic (freestream) conditions


I. Introduction
SPIN is an aggravated stall that results in autorotation [1].

http://profs.sci.univr.it/~zuccher/d...DS_JOA2007.pdf

A standard copybook 1G stall and spin entry has you arriving at the Critical AOA in 1G flight with close to full backstick. As the stall develops (ideally a nanofart before) you smoothly apply and hold full rudder (I guess you could say this is "aggravating" the stall ).

Any stall under any acceleration is aggravated. Anytime you have uncoordinated flight, you have lateral acceleration.

http://books.google.com/books?id=nxb...flight&f=false

The primary cause of an inadvertent spin is exceeding the critical AOA while applying excessive or insufficient rudder and, to a lesser extent, aileron. Insufficient or excessive control inputs to correct for Power Factor (PF), or asymmetric propeller loading, could aggravate the precipitation of a spin. At a high AOA the downward moving blade, which is normally on the right side of the propeller arc, has a higher AOA and therefore higher thrust than the upward moving blade on the left. This results in a tendency for the airplane to yaw around the vertical axis to the left. If insufficient or excessive rudder correction is applied to counteract PF, uncoordinated flight may result.

http://faculty.chicagobooth.edu/john...C%2061-67C.pdf