JP Mk5 Nose Strakes
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Mere mortal
Hello - is it possible you might give a date of such posting or reference?
I am meeting with the UK CAA shortly to get them to think again about their no aeros restriction - any information you could give on this matter would be very helpful
BW
Hello - is it possible you might give a date of such posting or reference?
I am meeting with the UK CAA shortly to get them to think again about their no aeros restriction - any information you could give on this matter would be very helpful
BW
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Maybe I can add a little extra.
I quizzed my friendly neighbourhood aerodynamicist boffin on this. As has already been mentioned, he agreed that the strakes were fitted to reduce the oscilliatory behaviour in yaw brought about by the differences in the JP Mk 5 front fuse. To quote: "At high incidence a conical body (like a front fuselage) can develop vortices that shed asymmetrically causing large oscillatory yawing moments. The strakes are there to 'fix' the vortices to eliminate oscillatory behaviour." He's normally right about these things and he convinced me.
Hope that helps.
WUT
I quizzed my friendly neighbourhood aerodynamicist boffin on this. As has already been mentioned, he agreed that the strakes were fitted to reduce the oscilliatory behaviour in yaw brought about by the differences in the JP Mk 5 front fuse. To quote: "At high incidence a conical body (like a front fuselage) can develop vortices that shed asymmetrically causing large oscillatory yawing moments. The strakes are there to 'fix' the vortices to eliminate oscillatory behaviour." He's normally right about these things and he convinced me.
Hope that helps.
WUT
Report you refer to claims it was a 5A 
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If you look at the venerable T-37, you will also see strakes along the nose which were added after tests showed some interesting spin handling.
You will notice their absence on the prototype http://tinyurl.com/3d86me
and their prominence on the production models including the A-37
http://tinyurl.com/2mtnly
You will notice their absence on the prototype http://tinyurl.com/3d86me
and their prominence on the production models including the A-37
http://tinyurl.com/2mtnly
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The T-37 had very weird spin behavior. The recovery technique was to get full AFT stick first - so that if the spin was inverted there would be a recovery. Only then was the classic rudder against spin direction and full forward stick applied.
There is a Powerpoint here that explains it all http://www.5oclock.org/StudentsSpinBrief.ppt
A less detailed version is in this pilot report http://www.airbum.com/pireps/PirepCessnaT-37.html
How did the USAF accept this behavior - would it have passed UK certification?
Worf
There is a Powerpoint here that explains it all http://www.5oclock.org/StudentsSpinBrief.ppt
A less detailed version is in this pilot report http://www.airbum.com/pireps/PirepCessnaT-37.html
How did the USAF accept this behavior - would it have passed UK certification?
Worf
"The INTRODUCER"
Cranwell JP loss
Nigel, I don't think that's right. I'm quite sure the Cranwell 1980 loss was a T5A - there were certainly no other models based at RAFC in that era. I'm reasonably sure the MoD report that you cite has the wrong registration (SW314) - without checking my log book, I'm pretty sure all the RAFC aircraft were XW......
And this unofficial data supports my view.
And this unofficial data supports my view.
"The INTRODUCER"
Nigel, sorry - the fact that you were quoting wasn't so obvious on the email alert where I read your message. My comment is indeed directed to Yellow Sun as you say.
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JP5 Strakes
Bit late in on this thread, but the following may be of interest. It comes straight from the gospel's mouth, the Gospel being Reggie Stock, ex Huntings and then BAe cheif test pilot for the Mighty Mouse in its various forms
1. The company had to do lots of work to correct the initially poor JP5 spin handling. Originally, the spin was very oscillatory, with large hesitations in roll, yaw and pitch throughout the spin, including roll reversal and pitch attitudes that varied from past the vertical to above the horizon.
2. Spin recovery from these oscillatory spins varied significantly, from immediate to prolonged – up to 2 turns, which is a long time for a basic training aircraft.
3. The oscillations got worse with reducing ful state. (He noted wryly that even though spin handling was unacceptable at near max fuel, they still completed a full programme down to low fuel weights, just to prove it! When Reggie is being wry, the rest of us would have a coronary)
4. They originally put the large strakes under the rear fuselage, but they made the spin even worse. (An aside from teadriver, rear strakes are the conventional place to put strakes, to reduce AOA in the spin. Just goes to show that spinning's still a black art.))
5. Putting the strakes under the nose cured the adverse handling completely.
6. Reggie reminded me that the primary recovery control in the spin is the rudder, and that it is important to correctly identify the direction of spin and then apply – and maintain – full anti-spin rudder until the rotation stops. Most of the RAF incidents occurred because the pilot did not maintain recovery rudder long enough, or changed rudder because he thought nothing was happening.
7. The JP 3 and 4 spin fine, except when carrying tip tank fuel, and with an asymmetric fuel state – the Pilot’s Notes cover that aspect well.
8. The roughened leading edges are there to improve aileron effectiveness at and during the stall. They have no effect in the spin, when the wing is effectively fully stalled.
9. The roughened walkways have no effect on stall or spin handling nor on drag and performance.
10. The rear fuselage strakes are there to try and reduce the amount of dutch roll (usually seen as snaking, i.e. mainly yaw with little roll) in normal cruising flight. The JP5, with it’s large cockpit and front fuselage area, was worse in this respect than the JP3 and 4. Those strakes have no effect on the spin.
1. The company had to do lots of work to correct the initially poor JP5 spin handling. Originally, the spin was very oscillatory, with large hesitations in roll, yaw and pitch throughout the spin, including roll reversal and pitch attitudes that varied from past the vertical to above the horizon.
2. Spin recovery from these oscillatory spins varied significantly, from immediate to prolonged – up to 2 turns, which is a long time for a basic training aircraft.
3. The oscillations got worse with reducing ful state. (He noted wryly that even though spin handling was unacceptable at near max fuel, they still completed a full programme down to low fuel weights, just to prove it! When Reggie is being wry, the rest of us would have a coronary)
4. They originally put the large strakes under the rear fuselage, but they made the spin even worse. (An aside from teadriver, rear strakes are the conventional place to put strakes, to reduce AOA in the spin. Just goes to show that spinning's still a black art.))
5. Putting the strakes under the nose cured the adverse handling completely.
6. Reggie reminded me that the primary recovery control in the spin is the rudder, and that it is important to correctly identify the direction of spin and then apply – and maintain – full anti-spin rudder until the rotation stops. Most of the RAF incidents occurred because the pilot did not maintain recovery rudder long enough, or changed rudder because he thought nothing was happening.
7. The JP 3 and 4 spin fine, except when carrying tip tank fuel, and with an asymmetric fuel state – the Pilot’s Notes cover that aspect well.
8. The roughened leading edges are there to improve aileron effectiveness at and during the stall. They have no effect in the spin, when the wing is effectively fully stalled.
9. The roughened walkways have no effect on stall or spin handling nor on drag and performance.
10. The rear fuselage strakes are there to try and reduce the amount of dutch roll (usually seen as snaking, i.e. mainly yaw with little roll) in normal cruising flight. The JP5, with it’s large cockpit and front fuselage area, was worse in this respect than the JP3 and 4. Those strakes have no effect on the spin.
Teadriver, seems strange that Hunting/BAe should put strakes on the rear fuselage, as all the fin/rudder are on the top and would have contributed to perhaps more fin/rudder blanking.It`s a more usual `fix` on piston/t`prop a/c where the lower half of the rudder extends to the bottom of the fuselage and is unshielded....still BAe move in mysterious ways ...and there aren`t any strakes on the rear, only the fin/tailplane fillets.
As a young stude TP, remember being hosted by Reggie and co. on the ETPS visit to Warton.. and then doing the rounds of various `establishments` later.. then trying to get back to a hotel , from somewhere on Blackpool prom in the middle of the night..all this before one learned to keep the hotel card down your sock ...Hope Reg is well...Syc.
As a young stude TP, remember being hosted by Reggie and co. on the ETPS visit to Warton.. and then doing the rounds of various `establishments` later.. then trying to get back to a hotel , from somewhere on Blackpool prom in the middle of the night..all this before one learned to keep the hotel card down your sock ...Hope Reg is well...Syc.
I remeber the incident. It was a Cranwell aircraft (therefore a 5A) which crashed very close to Swinderby. The instructor was blamed, and the posted report said it must have been the instructors fault as plenty of JPs had recovered from spins before. However, despite the modifications, it still wasn't a pleasant aircraft to spin. Generally, it was beingn but now and again you'd find one that wasn't. As I mentioned earlier, I nearly jumped out of one when a spin went oscillatory. It was very disorientating and it recovered just above abandon altitude, bottoming out below on the recovery! We snagged the aircraft and it was found to be well ouside the rigging limits.
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I remember vividly spins in the -37. My instructor, a great fellow later killed flying A-1s in Vietnam, was very calm as he walked us through the procedures. We cleared the area, climbed left, fed in right rudder and away we went. He went full aft on the stick and brought the throttles to idle all the while calmly talking. Once the spin had stabilized, we asked me to look at the turn and ball.. needle to the inside, ball to the outside. Meanwhile the brown Texas countryside was whirling around us with details becoming more and more clear. Airspeed.. very slow. VSI... a rapid descent. Ailerons neutral. Throttles idle. The earth is rushing up.. we are rushing down and this guy is talking as calmly as if he were buying veggies at the local grocery store. Bang! the stick goes forward and bounces back an inch or two. BAM! Opposite rudder and soon we are doing a high speed dive recovery. The guy was meticulous.
Later, on another sortie, we were preparing to do spins and found one fuel tank had collapsed and we were badly out limits. Had we spun, we probably would not have recovered. During my pre-solo with this fellow, we had 1 engine shutdown, 1 hyd failure (blow the gear down) and this tank collapse. Never once did he yell or get excited.
But besides the spin recovery, we were also taught a spin fly-out where we initiated the recovery before the spin stabilized. You could fairly easily bounce an instructor off the canopy during these.
The powerpoint you listed is an excellent presentation. Thanks.
Later, on another sortie, we were preparing to do spins and found one fuel tank had collapsed and we were badly out limits. Had we spun, we probably would not have recovered. During my pre-solo with this fellow, we had 1 engine shutdown, 1 hyd failure (blow the gear down) and this tank collapse. Never once did he yell or get excited.
But besides the spin recovery, we were also taught a spin fly-out where we initiated the recovery before the spin stabilized. You could fairly easily bounce an instructor off the canopy during these.
The powerpoint you listed is an excellent presentation. Thanks.
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I seem to remember reading somewhere that Reg Stock had an interesting experience spinning a production Strikey, with one tip tank full and the other empty; something about it "...recovering normally, after some 18 turns...."
"The INTRODUCER"
Rigging
Yes Dan, and there was "fleet 12" I think with its unidirectional stall-turn capability. I wonder how that spun?
(And before the purists strike - jets, stall-turns etc - I know, I know...)
(And before the purists strike - jets, stall-turns etc - I know, I know...)
