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Stalls & spins - any test pilot pireps out there?

 
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peterz(at)zutrasoft.com
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PostPosted: Thu Jan 20, 2022 8:40 am    Post subject: Stalls & spins - any test pilot pireps out there? Reply with quote

I am very curious as to the spin behaviour with full flaps - does it wind up like crazy?  Can it be recovered using standard procedure, or do the flaps (mono gear) require to be retracted?

I am also very curious as to how hard over the top it will spin from a gear/flaps-down  full rudder forward sideslip stall.
Any brave pireps out there?  .... or factory testing knowledge?
Many thanks,
PeteZ
C-GNPZ


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John Wighton



Joined: 18 May 2010
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PostPosted: Thu Jan 20, 2022 11:54 pm    Post subject: Re: Stalls & spins - any test pilot pireps out there? Reply with quote

Andy Draper or Ivan should be able to recall the exact FT schedule, but l believe that the FT test pilot did up to 12 rotations in all configurations.

There was also a comprehensive AGATE led trial in the states that may have included spin studies. That is worth reading in any case.

I had done incipient stage only, in accordance to UK approvals.

Other than for development flying, l am not sure why you would want to do dirty multiple spins?


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Europa XS trigear G-IPOD
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PostPosted: Fri Jan 21, 2022 3:51 am    Post subject: Stalls & spins - any test pilot pireps out there? Reply with quote

Thx John,

I'm not looking to do fully developed spins intentionally, but would like to be prepared for such if it becomes the result of a full sideslip stall with flaps. Fwiw, the Katana for example was scary fast on the spin with flaps and needed them to be retracted for recovery.
Thx again!
PeteZ
On Fri., Jan. 21, 2022, 3:02 a.m. John Wighton, <john(at)wighton.net (john(at)wighton.net)> wrote:

Quote:
--> Europa-List message posted by: "John Wighton" <john(at)wighton.net (john(at)wighton.net)>

Andy Draper or Ivan should be able to recall the exact FT schedule, but l believe that the FT test pilot did up to 12 rotations in all configurations. 

There was also a comprehensive AGATE led trial in the states that may have included spin studies.  That is worth reading in any case.

I had done incipient stage only, in accordance to UK approvals. 

Other than for development flying, l am not sure why you would want to do dirty multiple spins?

--------
John Wighton
Europa XS trigear G-IPOD




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JDA



Joined: 27 Sep 2021
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PostPosted: Fri Jan 21, 2022 8:07 am    Post subject: Re: Stalls & spins - any test pilot pireps out there? Reply with quote

According to the "Europa News No 3, March 1993" (Europa Aircraft Tech Tips No3 from the Europa Club Website): Norrie Groves, Chief Test Pilot Slingsby Aviation, carried out an independent test flights for the PFA. Having carried out preliminary spin testing, "...Norrie then went on to complete two turn spins to meet the full F.A.R. 23 requirement. This the Europa did with instant recovery at all c. of g.'s, flaps up, flaps down, gear up, gear down. Norrie went on then to put in reverse recovery controls after two turns and, in fact explored crossing controls to simulate a confused, inexperienced pilot. Europa still recovered easily. Norrie finished up the program with a four turn spin to both left and right. His comments were that the Europa was very reluctant to spin in the approach configuration (gear and flaps down)". See the original article for full info.
Regards,
John


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Peter pender



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PostPosted: Fri Jan 21, 2022 3:37 pm    Post subject: Re: Stalls & spins - any test pilot pireps out there? Reply with quote

Hi Pete,

Will have a go at crossed control stalls one day and report back, but as an aside I was quite surprised at the difference in accelerated stalls gear up and down(mono). In mine anyway if others are similar I can see why some have come to grief turning onto final.

Cheers Peter


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PostPosted: Fri Jan 21, 2022 4:46 pm    Post subject: Stalls & spins - any test pilot pireps out there? Reply with quote

Hi Peter,

Many thx for the info! At approx what speed and G did it break with mono flaps down? In a level pull-up, or bank? Sounds like a challenge to not overspeed the flaps. That is definitely something I’d like to try.

Sooo much to learn Smile

Cheers and thx again!
PeteZ

Ps- it will likely be a couple months before I get to testing, as i’m waiting to get some refresher and advanced training first in a local acro grob g-115. And why i was interested in hearing of any pireps to get some europa context. I am hoping Bud will also chime in when he’s recovered.

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On Jan 21, 2022, at 6:50 PM, Peter pender <ppen(at)live.com.au> wrote:



Hi Pete,

Will have a go at crossed control stalls one day and report back, but as an aside I was quite surprised at the difference in accelerated stalls gear up and down(mono). In mine anyway if others are similar I can see why some have come to grief turning onto final.

Cheers Peter




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Peter pender



Joined: 15 Jan 2021
Posts: 16

PostPosted: Fri Jan 21, 2022 5:40 pm    Post subject: Re: Stalls & spins - any test pilot pireps out there? Reply with quote

Hi Pete,
I just put gear down, roll 60 degrees, centre stick and pull until it stalls. G force is proportional to speed. I have the Europa stall warner which in my opinion is actually AOA and was testing that it gave some warning in all attitudes and it seems it does. Good idea to get some training or refresher and start high.

Cheers Peter


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budyerly@msn.com



Joined: 05 Oct 2019
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PostPosted: Sat Jan 22, 2022 1:09 pm    Post subject: Stalls & spins - any test pilot pireps out there? Reply with quote

Pete,
The Europa was fully spin tested and recovery explanations were made in one of the early Tech Talk Articles. 
Full discussion of stall strips is in the POH. 
 
Basic Spins:
Nearly all aircraft of any type require gear retraction and flap retraction as a spin recovery.  If it is not obvious to anyone why there is plenty of flight analysis of why in training manuals and on the internet.  In a nutshell why retract gear and flaps:  1.  Moment of inertia change during rotation due to the mass of the equipment, 2.  Flaps extended during the spin is detrimental to roll/spin char due to the leading/lagging aoa wing performance, 3.  Breaking the stall is more important than the initial retraction of the gear and flaps, 4.  Pitch stick forces with flaps down is sometimes lower and overcontrol is possible when employing forward stick to break the stall, 5.  During the recovery it is very difficult not to overspeed the gear and flaps, 6.  Retract the flaps early to avoid overspeed and get a clean wing for better recovery, 7. Some long wing aircraft have flap mechanisms that are flexible and flap retraction is prudent as the down aft rotating flap has issues that may cause structural issues.  C-162 and other aircraft use a cable and spring extension and retraction system that can cause the flaps to change position during the spin. 
 
Note that intentionally adding rudder or aileron to induce a spin is intentional spinning.  The Europa is not designed for intentional spinning.
 
My experience:
In my LSA testing and clean phase one testing the Europa aircraft is extremely quick to recover flaps up or down without VGs.  Part 23 testing procedures were used (similar to Europa initial tests) and simply releasing the controls stopped the 180 degree per second pro spin control in half a turn but once broken the stall left the aircraft quite nose low.  At any initial break with up to ½ rudder used for yaw, flapped or clean, rarely did recovery take over 90 degrees of wing drop for a stall.  Release of controls only with flaps in N12AY did roll nearly 135 degrees before the rotation ceased with my feet flat on the floor (no attempt to coordinate the stall entry or prevent it was made).  Using pro spin controls, the nose will be quite low and comfortable so the slow flap drive motor of a trigear will lead to a flap overspeed during recovery unless roll to wings level and immediate recovery is made from the dive.  Tests began at 9500 MSL and most were out of the departure from control through dive recovery with a 2 G pull by 8000 feet.  Floor of ops was 3500 MSL for safety, so a two turn full Part 23 spin was limited to a max of two turns (about 3000 foot loss then dive recovery of about 1000 feet with recovery to a climb by 5500 feet and a lazy low G recovery from the dive).  One clean stall spin entry accomplished by full cross control with a simple snap over the top and transition to a spin entry and simple neutral controls recovered immediately.  Addition of vortex generators at 60mm spacing prevented stall spin entry unless full deep stall backstick and full rudder were needed to induce the break.  Stall strips per the manual tended to prevent unannounced stall and allowed even deep stalls without loss of control with zero sideslip.  Only well out of center ball conditions in the stall caused a VG equipped wing drop.  In a clean wing Europa, the key to fully controlled deep stalls is concentrating over the nose and using rudder to immediately correct for and maintain nose track.  Most pilots fail to watch over the nose and rely on the somewhat damped and slow ball and are slow to note the nose moving due to P factor or trim.  This failure to notice the slip typically will lead to insufficient rudder to maintain coordinated flight as P factor is more pronounced than most would assume at idle power.
 
Before attempting stalls well into post stall, the aircraft rig and trim should be ideal.  Stall strips as per the POH are an excellent prestall warning as are other electronic devices and should be added and properly adjusted.
 
In the Europa, the initial roll rate or wing drop with an out of rig (ball) stall will be very high (90 degrees per second or higher).  However, no matter how bad the ball/side slip up to ½ rudder, a centering of the stick (pitch and roll) and neutral rudder immediately breaks the stall and stops rotation.  I found opposite rudder applied first is quicker stopping the initial post stall rotation and found leading the opposite rudder was not a large improvement in breaking the stall/spin but noticeable.  Those who attempt to correct stall approach wing drop with aileron require retraining/practice to improve their skills.  Rudder is the precise yaw control, any aileron input to attempt correction for the wing drop will exacerbate the stall and lean toward a spin entry.  Normally, if the starboard wing begins to drop, left stick will drop the right aileron and force the outboard starboard wing to abruptly stall.  In the case above as the wing begins to drop, relax back pressure to break the stall, and add left rudder necessary to stop nose movement.  A properly built and rigged Europa will tolerate small aileron input at the stall due to wing twist provided yaw is kept to a minimum.  There are videos on Youtube done by myself and others on stall demonstrations and the use of rudder as well as stick relaxation.
 
Side slips are not covered in the POH but are comfortable between 60-70 knots.  Cross wind landings using rudder to kick out the nose for runway alignment requires little aileron input and will positively hold the aircraft in a sideslip at a precise ground track even for moderate cross winds of 5-10 knots.  Operationally 15 knots steady state is about my personal limit in the mono.  I fear no reasonabl crosswind in the trigear.
 
Side slips to lose altitude or bleed speed when fully configured:
If excessively high, go around and replan your approach to compensate for the unintended initial landing plan.  In general, if you lower the nose a large power reduction is required to maintain speed.  Adjust the pattern for a 60 knot approach plus ½ the gust factor.  If idle power will not give you sufficient sink, add rudder and aileron as required to maintain ground track in a forward slip.  Do not push the nose excessively down as speed will build rapidly to over 70 Knots.  Maintain pitch for a 60-65 knot airspeed with cross controls allows a doubling of the sink rate from normal power off 60 knot final. 
 
If too fast (70 Kts) reduce power, hold the nose up a bit and apply sideslip controls.  Allow the speed to decrease to 60 knots and then lower the nose to maintain 60 knots.  It would be imprudent to raise the nose in a full sideslip to well below final approach speed as this could easily lead to a cross control stall.  It is uncomfortable to do this in the Europa (nose high, side slip attitude) and is counter intuitive to any flight training I know of. 
 
If slow and on final, a 55 Knot (about 5 knot slow approach) wings level straight ahead approach gives a high rate of sink power off and is acceptable provided the pitch is lowered and or power increased (or both) to regain a stabilized approach without overshooting glidepath (remember unloading and adding power will accelerate the aircraft faster than most would think).  Use caution in that an abrupt attempt to arrest the sink or attain a climb attitude and a late power application made at 55 knots can lead to a nose high well behind the power curve situation rapidly approaching a stall which the pilot may not be comfortable with or be able to recover from without a high sink impact or stall.  Never attempt to salvage a bad approach.
 
In my experience, full rudder applied in level flight clean will normally cause the fin to blank part of the opposite stabilator and the nose will drop quickly unloading the aircraft as speed approaches the stall when wings level.  In testing the LSA full rudder applied in level flight with full flaps was similar.  Beginning below 90 KIAS when approaching 50-55 Knots (about 5-10 Knots above the fully configured stall) the aircraft stab unloaded and the nose went down but was controllable as the stab blanked a bit.  No attempt at full rudder sideslip with opposite aileron decreasing airspeed down to stall was deemed prudent to test to.
 
Snap rolls are not permitted.  However, in limit testing I found that full rudder at the initial stall shudder caused a pronounced roll away from the ball.  Slightly accelerated stall approaches clean with full rudder and additional backpressure and opposite aileron induced a very quick roll which ceased immediately with relaxation of the stick pressure.  Again, this type flying is imprudent in a non aerobatic aircraft which is not stressed for snap rolls.  Cracks were found in the filler on the rudder and one aileron.  Repairs showed the glass was intact but it was obviously stressful.
 
For normal operations and crosswind operations think of the following:
Full aileron at the stall or at takeoff speed requires little control stick pressure (even experienced pilots lack the feel when pegging the stick at the stop during initial takeoff with a crosswind) and will place the down aileron wing close to the stall at initial takeoff.  Initially during the takeoff roll, start with excessive aileron then rapidly recenter the stick to hold the outriggers (wings) level.  Even the trigear can be rolled up on a single wheel abruptly near stall speed on the ground if the nose is raised for takeoff.  Initially during the takeoff roll, full aileron is rarely needed beyond 25 knots ground speed during takeoff.
 
In general, I have found:
Sideslips are easily accomplished between final approach speed and best glide speed.  Any faster is just flying sideways or if approaching the stall will exacerbate a high angle of attack increasing situation close to the stall.  To lose altitude one must also lose speed.  Pretty much light plane standard.
If above final approach speed, sideslip up to full rudder and aileron as required, to drop the speed toward your desired approach speed. 
If at final approach speed and still high (above glidepath), reduce power, if needed, sideslip using up to full rudder and aileron and use pitch as required to maintain final approach speed.   As the desired glide path is approached remove cross controls and add power as required to achieve the desired stabilized approach.
 
That is all I have in my notes.
 
Best Regards,
Bud Yerly
 
 
 
From: owner-europa-list-server(at)matronics.com <owner-europa-list-server(at)matronics.com> On Behalf Of Pete Zut
Sent: Thursday, January 20, 2022 11:39 AM
To: europa-list <europa-list(at)matronics.com>
Subject: Europa-List: Stalls & spins - any test pilot pireps out there?

 
I am very curious as to the spin behaviour with full flaps - does it wind up like crazy?  Can it be recovered using standard procedure, or do the flaps (mono gear) require to be retracted?
 

I am also very curious as to how hard over the top it will spin from a gear/flaps-down  full rudder forward sideslip stall.

 

Any brave pireps out there?  .... or factory testing knowledge?

 

Many thanks,

PeteZ

C-GNPZ


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rparigoris



Joined: 24 Nov 2009
Posts: 780

PostPosted: Sun Jan 23, 2022 2:01 pm    Post subject: Re: Stalls & spins - any test pilot pireps out there? Reply with quote

Hi Group When stalling Europa pulling some positive Gs, I believe the net effect of wing flexing upward at tips and design/geometry of aileron control has ailerons droop (less washout when pulling Gs). Nev had mentioned this to me and suggested to begin with 1/8" reflexed ailerons. Has anyone compared stalling when pulling Gs with reflexed ailerons compared with even ailerons? Results? I spoke with 1 owner that had at least 1/8" drooped ailerons and when I asked him about it, he said he was faster but it would spin like a maple leaf without not much coaxing. I think that was at 1G. Ron P.

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