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clivesutton
Joined: 23 Jan 2013
Posts: 187
Location: KENILWORTH
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 Posted: Tue Feb 16, 2021 1:17 am Post subject: Side-slipping the Europa? |
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I use side-slipping occasionally on final approaches/flapped. It can be a very useful way to lose altitude more quickly than usual.
But I can't find anything in the Mono owners manual on best practice/limits for side-slipping - can anyone enlighten me? Specifically:
1) Could/should one side-slip right down to stall+5kts?
2) Are there side-slip performance differences between Mono and Tri-Gear?
3) Are there any side-slipping 'gotchas' that i should be aware of?
Clive Sutton
G-YETI
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budyerly@msn.com
Joined: 05 Oct 2019
Posts: 281
Location: Florida USA
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| Posted: Tue Feb 16, 2021 7:29 am Post subject: Side-slipping the Europa? |
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Clive,
1. It is never prudent to sideslip down to the stall as an obvious spin will result. Final approach for a fully flapped approach of 1.3 stall (nominally 60 Knots IAS) would be the prudent limit of a side slip airspeed. In flight testing of mono and trigear, I side slip at 60 knots with a great boot of rudder, but there are limitations applicable to any aircraft. Operationally there is no requirement to excessively side slip an aircraft below final approach speed.
2. No figures have been published on the added rate of descent from a sideslip.
3. The Gotchas' are:
Side slips approaching the stall will cause the receding wing to stall quickly leading to a rapid roll and if aft stick and rudder are held as the aircraft departs, a spin will result. UNLOAD FOR CONTROL IMMEDIATELY ON DEPARTURE FROM CONTROLLED FLIGHT!
Most aircraft in level flight near approach speed can blank the tail plane if full rudder is applied. Again, at a safe altitude (3 mistakes high) one can get the full effect by simply slowing to about 70 knots, maintain level flight and add rudder until the stop. Allow the speed to bleed and as more up elevator/stabilator is added the rudder/fin and fuselage blanks one of the stabs. The blanked stab will lose its downforce causing a rapid unloading of the aircraft and nose down pitch attitude ensues. In some aircraft it is quite violent and unexpected (RV-8s will bounce your head off the canopy). In a side slip using full rudder the aircraft is somewhat unloaded as level flight is not being maintained and large amounts of up elevator/stab are not being used to maintain level flight so this unloading due to stab blanking is not experienced.
(When talking airspeed control, one must have his airspeed indicating system verified and calibrated. Flight test and corrections to the airspeed are necessary or you are talking apples to oranges. The Europa pitot/static tube on the XS is quite accurate when coupled to a properly indicating airspeed indicator normally, but calibration is still required.)
In my experience, side slips are used to correct errors in judgement. Normally due to my lax attention to airspeed sometimes I am forced to bleed off the excess on final if I don't want to float excessively. If at 70 Knots trying to get to 60, one must understand that the Europa is very clean and additional side slip does not give me a gratifying immediate response to being too fast while holding glide path. Also, if the pattern is tight, side slipping while trying to maintain a steeper than normal (2.5-3 degree) glide path, I find speed and altitude reduction is not comfortably fast in a sideslip. When going into a field that is shorter and the approach is guarded by high trees, I do side slip as the Europa will build speed quickly if quickly unloaded after crossing the trees to establish an aimpoint near the threshold (especially with a course propeller pitch). I find a side slip at 60 with about half rudder displacement gives a comfortable 5 degree glide slope if memory serves. It allows me to cross the threshold at a very controllable speed to allow me to establish the landing attitude with gratifying results.
The stabilized approach and adherence to airspeed control is a far better answer than side slipping with reckless abandon ( as I am sometimes forced into due to lack of attention). Personally, 80KIAS on downwind abeam touchdown. Apply full flaps, maintain 75 KIAS during the base leg/turn to final. Bleed off airspeed to 60KIAS during the rollout to final with pitch and power set. Maintain 60 KIAS until passing the field boundary. Reduce power, and adjust aimpoint and allow for a slight speed reduction to cross the threshold a few feet high at 55KIAS and the float is easy to control while settling into the ground effect area. Float is about 500 feet on a hot day over a hard surface.
Power control is essential. I teach that if you lower the nose (push over to shorten the aimpoint) one must pull the power back immediately or an instant 5 knots is gained. "If you push over, pull the power" seems to work well with my clients. On short field landings, I slow to cross the fence stabilized at 55KIAS with power on and bleed the rate of descent and speed to cross the threshold with a decreasing speed and a controllable rate of descent to a firm touchdown. I only float a couple hundred feet max past the threshold and am stopping in 600 to a 1000 feet on a hard surface. If forced to a steep approach over trees or dikes, to the landing zone, I find slowing a bit more to 55 gives a sink that is significantly greater than 60KIAS, which allows me to concentrate on a wings level approach, but the 55 knot steep near idle power approach also limits the amount of time to arrest the sink rate, and establish the flare. On grass strips with trees or power lines I tend to hold 60 until over the lines, then reduce power, lower the nose, sideslip a bit to drop in a bit quicker and use the extra speed to arrest the steep descent which bleeds the speed to 55 knots anyway and then go for the landing attitude.
When I really screw the approach I just go around and get my stuff together. If I've never landed on a field before or the conditions are not favorable for mistakes, I tend to do a very low approach (drag the field in a slow flight) sizing up the landing zone and wind conditions before making my approach and landing for real. I look for a point where a safe go around can be accomplished if I screw the approach to landing. That makes the final a very comfortable skilled looking landing and uneventful roll out.
Best Regards,
Bud Yerly
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Duncan McFadyean
Joined: 18 Jan 2011
Posts: 218
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| Posted: Tue Feb 16, 2021 7:54 am Post subject: Side-slipping the Europa? |
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Any views (anyone) of the differences of stall and/or spin behaviour in ground effect (I.e. within one-wing span height of the ground)?
Either theoretical or actual.
Duncan McF [quote] <![endif]--> 90 Clean Clean false false false EN-US X-NONE X-NONE <![endif]--> <![endif]-->/* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-hansi-font-family:Calibri; mso-bidi-font-family:"Times New Roman";} <![endif]--> <![endif]--> <![endif]--> On 16 February 2021 at 15:28 Bud Yerly <budyerly(at)msn.com> wrote:
Clive,
1. It is never prudent to sideslip down to the stall as an obvious spin will result. Final approach for a fully flapped approach of 1.3 stall (nominally 60 Knots IAS) would be the prudent limit of a side slip airspeed. In flight testing of mono and trigear, I side slip at 60 knots with a great boot of rudder, but there are limitations applicable to any aircraft. Operationally there is no requirement to excessively side slip an aircraft below final approach speed.
2. No figures have been published on the added rate of descent from a sideslip.
3. The Gotchas' are:
Side slips approaching the stall will cause the receding wing to stall quickly leading to a rapid roll and if aft stick and rudder are held as the aircraft departs, a spin will result. UNLOAD FOR CONTROL IMMEDIATELY ON DEPARTURE FROM CONTROLLED FLIGHT!
Most aircraft in level flight near approach speed can blank the tail plane if full rudder is applied. Again, at a safe altitude (3 mistakes high) one can get the full effect by simply slowing to about 70 knots, maintain level flight and add rudder until the stop. Allow the speed to bleed and as more up elevator/stabilator is added the rudder/fin and fuselage blanks one of the stabs. The blanked stab will lose its downforce causing a rapid unloading of the aircraft and nose down pitch attitude ensues. In some aircraft it is quite violent and unexpected (RV-8s will bounce your head off the canopy). In a side slip using full rudder the aircraft is somewhat unloaded as level flight is not being maintained and large amounts of up elevator/stab are not being used to maintain level flight so this unloading due to stab blanking is not experienced.
(When talking airspeed control, one must have his airspeed indicating system verified and calibrated. Flight test and corrections to the airspeed are necessary or you are talking apples to oranges. The Europa pitot/static tube on the XS is quite accurate when coupled to a properly indicating airspeed indicator normally, but calibration is still required.)
In my experience, side slips are used to correct errors in judgement. Normally due to my lax attention to airspeed sometimes I am forced to bleed off the excess on final if I don't want to float excessively. If at 70 Knots trying to get to 60, one must understand that the Europa is very clean and additional side slip does not give me a gratifying immediate response to being too fast while holding glide path. Also, if the pattern is tight, side slipping while trying to maintain a steeper than normal (2.5-3 degree) glide path, I find speed and altitude reduction is not comfortably fast in a sideslip. When going into a field that is shorter and the approach is guarded by high trees, I do side slip as the Europa will build speed quickly if quickly unloaded after crossing the trees to establish an aimpoint near the threshold (especially with a course propeller pitch). I find a side slip at 60 with about half rudder displacement gives a comfortable 5 degree glide slope if memory serves. It allows me to cross the threshold at a very controllable speed to allow me to establish the landing attitude with gratifying results.
The stabilized approach and adherence to airspeed control is a far better answer than side slipping with reckless abandon ( as I am sometimes forced into due to lack of attention). Personally, 80KIAS on downwind abeam touchdown. Apply full flaps, maintain 75 KIAS during the base leg/turn to final. Bleed off airspeed to 60KIAS during the rollout to final with pitch and power set. Maintain 60 KIAS until passing the field boundary. Reduce power, and adjust aimpoint and allow for a slight speed reduction to cross the threshold a few feet high at 55KIAS and the float is easy to control while settling into the ground effect area. Float is about 500 feet on a hot day over a hard surface.
Power control is essential. I teach that if you lower the nose (push over to shorten the aimpoint) one must pull the power back immediately or an instant 5 knots is gained. "If you push over, pull the power" seems to work well with my clients. On short field landings, I slow to cross the fence stabilized at 55KIAS with power on and bleed the rate of descent and speed to cross the threshold with a decreasing speed and a controllable rate of descent to a firm touchdown. I only float a couple hundred feet max past the threshold and am stopping in 600 to a 1000 feet on a hard surface. If forced to a steep approach over trees or dikes, to the landing zone, I find slowing a bit more to 55 gives a sink that is significantly greater than 60KIAS, which allows me to concentrate on a wings level approach, but the 55 knot steep near idle power approach also limits the amount of time to arrest the sink rate, and establish the flare. On grass strips with trees or power lines I tend to hold 60 until over the lines, then reduce power, lower the nose, sideslip a bit to drop in a bit quicker and use the extra speed to arrest the steep descent which bleeds the speed to 55 knots anyway and then go for the landing attitude.
When I really screw the approach I just go around and get my stuff together. If I've never landed on a field before or the conditions are not favorable for mistakes, I tend to do a very low approach (drag the field in a slow flight) sizing up the landing zone and wind conditions before making my approach and landing for real. I look for a point where a safe go around can be accomplished if I screw the approach to landing. That makes the final a very comfortable skilled looking landing and uneventful roll out.
Best Regards,
Bud Yerly
--
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clivesutton
Joined: 23 Jan 2013
Posts: 187
Location: KENILWORTH
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| Posted: Tue Feb 16, 2021 8:02 am Post subject: Re: Side-slipping the Europa? |
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Hi Bud,
As always, a full and easy-read answer, thanks and all your cautions acknowledged. Ivan gave me a similar steer off-BB - suggesting about 1.3 x VSo which for me would be ~56Kt with a proven flapped stall of 43Kt. So i will mentally note the ideal to be ~60kt (so holding a bit of a margin for speed errors), and not side-slip at speeds lower than that in the course of my handling practice. I agree fully that they are a bit of a "correction maneuver" and whilst i don't use them routinely, there are a few situations (like forced power-off landings or where a go-around is especially tricky etc) where they could be very helpful.
Best regards,
Clive.
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rparigoris
Joined: 24 Nov 2009
Posts: 780
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| Posted: Tue Feb 16, 2021 12:45 pm Post subject: Re: Side-slipping the Europa? |
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Hi Bud Great info as always, thank you. Few more questions about slipping, specifically on 914 Mono XS: Does airspeed work pretty good in both left and right side slips with airspeed/pitot in factory position? Mono with gear and airbrake slots not covered, what's the best way to get exhaust into the cockpit? As far as power setting, left or right slip? Ron P.
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budyerly@msn.com
Joined: 05 Oct 2019
Posts: 281
Location: Florida USA
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| Posted: Tue Feb 16, 2021 1:38 pm Post subject: Side-slipping the Europa? |
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Ron,
By the design of the static port on the XS a side slip has little effect on the static like in many fuselage mounted static ports so the airspeed does not jump around slipping right or left. Even on IFR aircraft I use the static port but I also install a cabin alternate static when called for. As I've said in other documents, in my experience the cockpit static is less than 2 knots and 25 feet from stall speed to cruise.
The best way to get exhaust smell into the cockpit is actually placing a vent where shown on the side of the aircraft tunnel near the pilots knee. Move the air inlet up to near the bond line or leave the long tail pipe because at speeds from 75 to 90 in a climb the exhaust comes right into mine due to the short stack. I can even see a small amount of soot tracking from my exhaust pipe up over the wing and directly into my NACA. I am forced to fly with my pilot side NACA vent closed all the time except at cruise. NASTY!
<![endif]--><![if !vml]>[img]cid:image001.png(at)01D70481.DF049230[/img]<![endif]><![endif]-->
Mono exhaust with the 912/914 XS exhaust with the proper sized exhaust down pipe seems to work fine avoiding any exhaust smell during pattern work and side slips. The Jabiru and Classic aircraft exhaust is normally through the exit duct right down or nearly down the centerline and can enter the wheel well. The Jabiru Trigear is not a problem. The 912 Classic with the exhaust angled down and to the side seems to be OK also. At cruise there is quite a bit of air that comes through the gear handle and brake during cruise. But I have not seen the CO monitor ever alarm or smell exhaust. It just gets cold on the hands at high cruise altitudes, but then again, I'm from Florida. 72F is cold for me.
Hopefully, other mono owners will have other ideas on sealing the mono. A small gap and a simple smoothing fairing around the wheel that laps the belly would be enough I would think. However, one should use caution on installing fairings on the gear as the fairing must not interfere with retraction or extension. I'd hate to fly in the winter with slush in my gear door freezing and locking my gear up. That's part of that 20,000 compromises we make.
Regards,
Bud Yerly
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davidjoyce(at)doctors.org
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| Posted: Tue Feb 16, 2021 3:03 pm Post subject: Side-slipping the Europa? |
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Ron and Clive, Bud has as ever given excellent answers, but perhaps I can add a bit. Firstly I would always side slip with Right rudder in a Europa as you then have excellent view ahead assuming you are in the Left hand seat, whereas left rudder slips restrict your view considerably. I find full right rudder side slipping at 60 kts very stable, easy to control and easy to straighten and it will produce 1000fpm descent instead of the 550 fpm in a straight 60kt idling approach. I personally deliberately approach high on a PFL and then burn off the extra height by sideslipping to allow for the possibility that you have hit a strong wind gradient and dropped well below your original aiming point. - how often do you find yourself having to put in a burst of power at around 200ft if you are aiming to touch down on the piano keys?
Wouldn’t it be great to be able to get our planes out and go flying?
Regards, David Joyce, GXSDJ
On 2021-02-16 20:45, rparigoris wrote:
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peterz(at)zutrasoft.com
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| Posted: Tue Feb 16, 2021 3:52 pm Post subject: Side-slipping the Europa? |
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as always, Bud's insights are great!
that said, FWIW, my classic's gear slot is absolutely, definitely negative pressure wrt to the cabin, proved by repeated tests with paper and fabric getting sucked onto the slots.
I believe most of the ingress of any exhaust in my ship is through the flap drive slots, when they are extended.
Cheers,
Pete
On Tue, Feb 16, 2021 at 4:49 PM Bud Yerly <budyerly(at)msn.com (budyerly(at)msn.com)> wrote:
[quote]
Ron,
By the design of the static port on the XS a side slip has little effect on the static like in many fuselage mounted static ports so the airspeed does not jump around slipping right or left. Even on IFR aircraft I use the static port but I also install a cabin alternate static when called for. As I've said in other documents, in my experience the cockpit static is less than 2 knots and 25 feet from stall speed to cruise.
Â
The best way to get exhaust smell into the cockpit is actually placing a vent where shown on the side of the aircraft tunnel near the pilots knee. Move the air inlet up to near the bond line or leave the long tail pipe because at speeds from 75 to 90 in a climb the exhaust comes right into mine due to the short stack. I can even see a small amount of soot tracking from my exhaust pipe up over the wing and directly into my NACA. I am forced to fly with my pilot side NACA vent closed all the time except at cruise. NASTY!
[img]cid:177ad3f45924cff311[/img]
Mono exhaust with the 912/914 XS exhaust with the proper sized exhaust down pipe seems to work fine avoiding any exhaust smell during pattern work and side slips. The Jabiru and Classic aircraft exhaust is normally through the exit duct right down or nearly down the centerline and can enter the wheel well. The Jabiru Trigear is not a problem. The 912 Classic with the exhaust angled down and to the side seems to be OK also. At cruise there is quite a bit of air that comes through the gear handle and brake during cruise. But I have not seen the CO monitor ever alarm or smell exhaust. It just gets cold on the hands at high cruise altitudes, but then again, I'm from Florida. 72F is cold for me.
Â
Hopefully, other mono owners will have other ideas on sealing the mono. A small gap and a simple smoothing fairing around the wheel that laps the belly would be enough I would think. However, one should use caution on installing fairings on the gear as the fairing must not interfere with retraction or extension. I'd hate to fly in the winter with slush in my gear door freezing and locking my gear up. That's part of that 20,000 compromises we make.
Â
Regards,
Bud Yerly
Â
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peterz(at)zutrasoft.com
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| Posted: Tue Feb 16, 2021 3:53 pm Post subject: Side-slipping the Europa? |
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fwiw, I'm with David on this, my experience as well.
Cheers,
Pete
Mono Classic
On Tue, Feb 16, 2021 at 6:13 PM <davidjoyce(at)doctors.org.uk (davidjoyce(at)doctors.org.uk)> wrote:
| Quote: |
Ron and Clive, Bud has as ever given excellent answers, but perhaps I can add a bit. Firstly I would always side slip with Right rudder in a Europa as you then have excellent view ahead assuming you are in the Left hand seat, whereas left rudder slips restrict your view considerably. I find full right rudder side slipping at 60 kts very stable, easy to control and easy to straighten and it will produce 1000fpm descent instead of the 550 fpm in a straight 60kt idling approach. I personally deliberately approach high on a PFL and then burn off the extra height by sideslipping to allow for the possibility that you have hit a strong wind gradient and dropped well below your original aiming point. - how often do you find yourself having to put in a burst of power at around 200ft if you are aiming to touch down on the piano keys?
Wouldn’t it be great to be able to get our planes out and go flying?
Regards, David Joyce, GXSDJ Â
On 2021-02-16 20:45, rparigoris wrote:
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