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Old 7th Aug 2001, 02:40
  #41 (permalink)  
 
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Cool

Just as another point of view,

I sometimes execute a run in and break at my home airfield as a nice way to end a sortie.
If I intend to do one, I always pre-brief ATC before the sortie and ask their permission.

I never break into the circuit if there are anymore than 2 other a/c in the cct.

Being ex-mil, I am tempted to use "Initials" and "On the break to roll/land" etc, but only I would know what they mean (unless there were anly other ex mil/current mil in the cct). My preferred "civvy phraseology" is:

"Long final, low approach to go around, request low level cct "

Verbose I know, but gives everyone else in the circuit the big picture. Air Traffic seem quite happy with this.

Although it is common sense, PPL's should be wary about run and breaks unless taught and demo'd. It is very easy to overcook it and stitch up others in the circuit by poor judgement. Watch that stalling speed too!

PS for those that know me, my home flying airfield is not Ice Station Zebra!!!!

[ 06 August 2001: Message edited by: The Jaguar Fan Club ]
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Old 4th Nov 2005, 22:25
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And as you are aware, a wing does not stall at a speed..........only an angle of attack.....which is almost certainly nothing like what you would expect during your completely unneccesary and pointless r&b manoevre in your Yak 50.
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Old 4th Nov 2005, 22:34
  #43 (permalink)  
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Old 5th Nov 2005, 00:37
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A little less conversation,
a little more aviation...
 
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Wow - I make that 4 years, 2 months, 28 days to respond -
good job Fast Erect is in a job that doesn't need swift
reaction times, eh?
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Old 5th Nov 2005, 07:20
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I knew I had registered with pprune before 2003

.....post on page one by myself says I havent registered yet

Regards, SD..
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Old 5th Nov 2005, 08:54
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Fast Erect

As you are aware, the IAS at which an aerofoil stalls varies with angle of attack and G so therefore a caution for PPLs who are taught "stalling speeds" and maybe want to "try out" a VRIAB is justified in my opinion. However as I said before, I recommend that pilots do not attempt a VRIAB unless correctly taught and demo'd.

...your completely unneccesary and pointless r&b manoevre in your Yak 50.
Not really pointless as it was good to maintain currency between leaving the military and now routinely operating formations around the bazaars.

I have never flown a Yak 50...maybe a little more research and mature conversation is in order before you wade in with your big w*nky boots?
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Old 5th Nov 2005, 15:49
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As you are aware, the IAS at which an aerofoil stalls varies with angle of attack and G
That doesn't read quit right. For a given wing there is only one critical angle of attack regardless of weight, G, etc (ignoring flaps and wor not). You seem to be implying that at another AoA, if you keep the speed up you won't stall.
 
Old 5th Nov 2005, 16:16
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Not quite.....I refer to Accelerated or "G" Stalls and I quote:

"This is a condition where the wing cannot produce enough lift to support the aircraft's weight and centrifugal force, in spite of otherwise flying at a reasonable airspeed and angle of attack. This can occur when an aircraft is in a tight turn, a high-G pull-up, or other manoeuvre where directions is changed with a significant amount of acceleration. This additional acceleration results in a high force that must be borne by the wings. In recent years there have been a number of accidents arising from Accelerated stalls in high-performance aircraft (e.g. the Jet Provost) that have been sold into the civilian sector from the military. Turbulence can cause an accelerated stall if the aircraft is flying below Vno (maximum structural cruising speed. If flying above Vno, turbulence can cause structural failure."

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Old 5th Nov 2005, 20:48
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Hi TJFC,
This is a condition where the wing cannot produce enough lift to support the aircraft's weight and centrifugal force, in spite of otherwise flying at a reasonable airspeed and angle of attack.
I suspect I've gawn off on one and that we agree. It is just the "and" bit I have issue with in that Wikipedia explanation you quoted. Ignoring the misleading bit about a stall being lift unable to support weight, you will never ever never stall at a "reasonable" angle of attack (where reasonable<crit alpha). An accelerated stall is merely the need for you to increase AoA past critical alpha to cope with the increased demands on the wing due to G/weight/etc.

 
Old 5th Nov 2005, 22:59
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TJFC,

I hardly think a Jet Provost is a high performance aeroplane. Get a grip boy and leave the military tosh behind

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Old 6th Nov 2005, 06:24
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High performance is a relative term.

In the world of SEP, a JP is a high performance aircraft - think C150 or Cherokee as the reference point.
 
Old 6th Nov 2005, 08:43
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If you want to play being an FJ pilot then join the RAF or if ex RAF then leave it all behind. A civilian airfield, unless covered by radar and empty airspace, is no place for military type games.
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Old 6th Nov 2005, 10:12
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HWD

I used that Wikipedia explanation to try and keep things simple but obviously that was the wrong thing to do. In an accelerated stall it is the wing loading and NOT the AoA that is critical. With the same angle of attack, the airspeed at which the stall occurs will be increased by the square root of the G. therefore at "high" g, the aerofoil will stall at a higher IAS and lower AoA than a "standard" stall.

Fast erect
Define "performance" aeroplane...The JP was selected by the RAF for its "performance". Over 300kts, +6.5g, pressurised with a service ceiling of over 36000ft (on the mk 5 obviously) and fully aerobatic seems perfectly within the bracket of performance to me.

Working Hard
The majority of those undertaking "war games" do so for the preserve of our military aviation history and are properly trained to do so with adequate agreements in place at home airfields to take account of the differences. What radar has to do with it I'm not sure... With your kind of attitude we would have none of these vintage types flying at all and Duxford would be another field full of "spamcans" or houses!

Last edited by The Jaguar Fan Club; 8th Nov 2005 at 13:44.
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Old 6th Nov 2005, 10:35
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With the same angle of attack, the airspeed at which the stall occurs will be increased by the square root of the G. therefore at "high" g, the aerofoil will stall at a higher IAS and lower AoA than a "standard" stall.
I really truely didn't realise that Why would the air seperate from the wing if the relative wind was below crit alpha?
 
Old 6th Nov 2005, 10:40
  #55 (permalink)  

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Have we not been here and done that?

http://www.pprune.org/forums/showthr...Run+and+breaks

Love

F.
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Old 6th Nov 2005, 11:56
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HWD

Think outside of the box...

In a standard stall, when the critical alpha is reached or exceeded, the relative airflow around the aerofoil is disturbed and lift is reduced.

An accelerated stall is not the same as a "Standard" stall. The problem is that the increased wing loading means that the aerofoil is not producing enough lift to oppose the effect of gravity or "g". This is why there is a relationship between IAS and G. The higher the g, the more airspeed you need to generate more lift to counteract the wing loading. Think of it as a "heavy" aircraft. You would need a faster Vr to get airborne at heavy weight than at light weight because the wing needs to produce more lift to overcome weight/gravity.

Hope that is a bit clearer...
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Old 6th Nov 2005, 12:22
  #57 (permalink)  
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Hi again TJFC,
Think outside of the box...
Ordinarily I would, but it is raining quite hard you know.
You would need a faster Vr to get airborne at heavy weight than at light weight because the wing needs to produce more lift to overcome
Sorry to drag this out Yes, I consider that obvious to any pilot and isn't quite the issue I have.
An accelerated stall is not the same as a "Standard" stall.
I suspected this was a mis-understanding due to terminology.

My use of the term "accelerated stall" implies that the wing did stall, that seperation occurs, but at Vs * SQRT(G or difference in weight). Also, that this seperation only occurs at crit alpha. It is also very nasty stall because inevitibly it is effectively power on stall in a prop and hence a tip stall.
 
Old 6th Nov 2005, 16:13
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Last edited by WorkingHard; 8th Nov 2005 at 19:32.
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Old 6th Nov 2005, 19:10
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alpha

In an accelerated stall it is the wing loading and NOT the AoA that is critical. With the same angle of attack, the airspeed at which the stall occurs will be increased by the square root of the G. therefore at "high" g, the aerofoil will stall at a higher IAS and lower AoA than a "standard" stall.
TJFC

Whilst I agree with you over your use of R & Bs (I found them invaluable at maintaining currency with and practising for low-level aeros for display purposes - in the correct circumstances, naturally, before anyone jumps on that), I have to take issue with your comments re "accelerated stalls".

The wing will always stall at the same AofA, whatever the wing loading. After all, wing loading is only a function of lift. What you should be looking at, for your argument, is what happens when you increase the wing loading at a given airspeed. The only way to do this is to increase the alpha and hence the lift. When the alpha reaches critical, then the wing will stall. As an aside, on conventional SEP etc, AofA is proportional to elevator and hence stick position. Have a look at the stick position next time and see when the stall occurs for various 'g' loadings!

regards

TAC
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Old 7th Nov 2005, 19:56
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RIAB's are a military technique used to recover jets on fuel minima efficiently and expeditiously whilst coping with formation aspects. Something I doubt very much that the likes of Fast Erect has ever had to cope with. By the sounds of it, the only fast thing about him/her is their username.

Why therefore start claiming they are about 'oneupmanship' etc, my dear freind you do make yourself sound like a prize @rse talking like that. If you cant cope with a bit of punchiness and finesse then I do really think you are in the wrong profession.

Let me guess, you prefer a radar - ILS with a couple of procedural holds for sh!ts and giggles, on standby instruments of course no doubt.

I really look forward to your reply as I expect it will be as pompous and as mundane as your previous posts, and allow me a few more giggles.

Yours

DS
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