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Stalling the TR-1

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jeffbudner

Joined: 20 Aug 2020
Posts: 18
Location: Rio Vista airport

Posted: Fri Mar 19, 2021 9:57 am Post subject: Stalling the TR-1

Hi all, I am on the 6th month of my TR-1 ownership, and I'm really enjoying the aircraft. When I first got the plane I was advised to take extra care to not stall the aircraft, but even intentionally at altitude due to the unruly stall characteristics that they experience themselves. This is the first aircraft I have flown in which I have no sense of what to expect in the event of a stall.



It would be helpful to hear from others that have experienced stalling their KIS, especially accelerated and power-off stalls. 



Thanks for the feedback.



Jeff

KIS TR-1 #099

pastormac62

Joined: 07 Sep 2015
Posts: 71
Location: Indiana

Posted: Fri Mar 19, 2021 10:01 am Post subject: Stalling the TR-1

Hi Jeff,

The two I owned were pretty benign. I however placed vortex generators under the surface of the horizontal elevator. They helped a lot and on landing as well. 



To our success, Stephen McIntosh 



 	  Quote: 	
		   On Mar 19, 2021, at 1:57 PM, jeffbudner <jeffbudner(at)gmail.com> wrote:

 

 

 

 Hi all, I am on the 6th month of my TR-1 ownership, and I'm really enjoying the aircraft. When I first got the plane I was advised to take extra care to not stall the aircraft, but even intentionally at altitude due to the unruly stall characteristics that they experience themselves. This is the first aircraft I have flown in which I have no sense of what to expect in the event of a stall.

 

 It would be helpful to hear from others that have experienced stalling their KIS, especially accelerated and power-off stalls. 

 

 Thanks for the feedback.

 

 Jeff

 KIS TR-1 #099

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=501017#501017

jeffbudner

Joined: 20 Aug 2020
Posts: 18
Location: Rio Vista airport

Posted: Fri Mar 19, 2021 10:17 am Post subject: Re: Stalling the TR-1

Thanks Stephen, I have a friend that is having success, in his TR-1, with VG's on the wings, I hadn't heard of anyone adding them to the elevator. Was you motivation to improve elevator authority in order to better control nose wheel touchdown or were you motivated by some other characteristic?

Jeff

KIS TR-1 #099

pastormac62

Joined: 07 Sep 2015
Posts: 71
Location: Indiana

Posted: Fri Mar 19, 2021 11:16 am Post subject: Stalling the TR-1

Hi Jeff,

Yes, better elevator authority!  It made a huge difference!!  I placed them underneath the elevator. 



To our success, Stephen McIntosh 



 	  Quote: 	
		   On Mar 19, 2021, at 2:17 PM, jeffbudner <jeffbudner(at)gmail.com> wrote:

 

 

 

 Thanks Stephen, I have a friend that is having success, in his TR-1, with VG's on the wings, I hadn't heard of anyone adding them to the elevator. Was you motivation to improve elevator authority in order to better control nose wheel touchdown or were you motivated by some other characteristic?

 

 

 Jeff

 KIS TR-1 #099

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=501019#501019

hans.erstad(at)gmail.com
Guest

Posted: Fri Mar 19, 2021 12:27 pm Post subject: Stalling the TR-1

Hi, Jeff

Nice to hear from new people experiencing KIS.

If you fly an aircraft slow enough  it is normal to stall.

The TR-1  have a quite high nose attitude when speed is slow, and you will probably not get there unintentionally.

But you should do a lot of stalls at good altitude.  Try with a passenger/aft CG, and you will get a quite different experience.  The stall depend more on CG position than power or accelerated. Know where you CG are compared to the CG limits stated.

But if surely flicks.  I have also experienced a flick in one direction followed by a flick in the other direction.

But a stall/flick always end up with the nose pointing downwards, speed increasing and control re-gained.  But you will always loose altitude.

Practice this a lot, and then you will get an understanding that you have to monitor airspeed in the pattern and approach.  

Speed control on approach is also important, not only to not stall, but also to be able to get down at all. If you are high on the approach you cannot move the stick forward. If you let the speed increase, you overshoot.  Control the approach angle by power only.  Airspeed constant.  That is probably how you learned to fly, and this aircraft have to be flown that way.

I have also flown other aircraft with similar stall characteristics, but that has not been a Cessna.

Regards, Hans



KIS TR-1 #032



fre. 19. mar. 2021 kl. 18:58 skrev jeffbudner <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>:



 	  Quote: 	
		  --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com>

 

 Hi all, I am on the 6th month of my TR-1 ownership, and I'm really enjoying the aircraft. When I first got the plane I was advised to take extra care to not stall the aircraft, but even intentionally at altitude due to the unruly stall characteristics that they experience themselves. This is the first aircraft I have flown in which I have no sense of what to expect in the event of a stall.

 

 It would be helpful to hear from others that have experienced stalling their KIS, especially accelewith rated and power-off stalls. 

 

 Thanks for the feedback.

 

 Jeff

 KIS TR-1 #099

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=501017#501017

 

 

 

 

 

 

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GalinHdz

Joined: 08 Nov 2017
Posts: 150

Posted: Fri Mar 19, 2021 2:34 pm Post subject: Stalling the TR-1

I can't speak about the TR-1 but the TR-4 has excellent stall characteristics during both power on and power off. I would recommend you do some in flight stall testing as if the airplane was undergoing phase 1 testing.



Get to an appropriate altitude and, with power off, come close to a stall (imminent) then recover. Next time go a bit deeper into the imminent stall and recover. Do this until you are either comfortable doing a full stall or don't think it is appropriate to go any further. Only you can decide what is appropriate.

Hopefully you will find your airplane handles just like the other TR-1's out there flying.

On Fri, Mar 19, 2021 at 4:28 PM Hans Christian Erstad <hans.erstad(at)gmail.com (hans.erstad(at)gmail.com)> wrote:



 	  Quote: 	
		  Hi, Jeff

Nice to hear from new people experiencing KIS.

If you fly an aircraft slow enough  it is normal to stall.

The TR-1  have a quite high nose attitude when speed is slow, and you will probably not get there unintentionally.

But you should do a lot of stalls at good altitude.  Try with a passenger/aft CG, and you will get a quite different experience.  The stall depend more on CG position than power or accelerated. Know where you CG are compared to the CG limits stated.

But if surely flicks.  I have also experienced a flick in one direction followed by a flick in the other direction.

But a stall/flick always end up with the nose pointing downwards, speed increasing and control re-gained.  But you will always loose altitude.

Practice this a lot, and then you will get an understanding that you have to monitor airspeed in the pattern and approach.  

Speed control on approach is also important, not only to not stall, but also to be able to get down at all. If you are high on the approach you cannot move the stick forward. If you let the speed increase, you overshoot.  Control the approach angle by power only.  Airspeed constant.  That is probably how you learned to fly, and this aircraft have to be flown that way.

I have also flown other aircraft with similar stall characteristics, but that has not been a Cessna.

Regards, Hans



KIS TR-1 #032



fre. 19. mar. 2021 kl. 18:58 skrev jeffbudner <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>:



 	  Quote: 	
		  --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com>

 

 Hi all, I am on the 6th month of my TR-1 ownership, and I'm really enjoying the aircraft. When I first got the plane I was advised to take extra care to not stall the aircraft, but even intentionally at altitude due to the unruly stall characteristics that they experience themselves. This is the first aircraft I have flown in which I have no sense of what to expect in the event of a stall.

 

 It would be helpful to hear from others that have experienced stalling their KIS, especially accelewith rated and power-off stalls. 

 

 Thanks for the feedback.

 

 Jeff

 KIS TR-1 #099

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=501017#501017

 

 

 

 

 

 

 ===========

 igator?KIS-List

 ===========

  FORUMS -

 /a>

 ===========

 WIKI -

 >

 ===========

 b Site -

           -Matt Dralle, List Admin.

 tribution

 ===========

GalinHdz

Joined: 08 Nov 2017
Posts: 150

Posted: Fri Mar 19, 2021 2:38 pm Post subject: Stalling the TR-1

FWIW I placed VG's under the elevator and they made a nice difference. 



On Fri, Mar 19, 2021 at 3:16 PM <pastormac(at)comcast.net (pastormac(at)comcast.net)> wrote:



 	  Quote: 	
		  --> KIS-List message posted by: pastormac(at)comcast.net (pastormac(at)comcast.net)

 

 Hi Jeff,

 Yes, better elevator authority!  It made a huge difference!!  I placed them underneath the elevator. 

 

 To our success, Stephen McIntosh 

 

 > On Mar 19, 2021, at 2:17 PM, jeffbudner <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)> wrote:

 > 

 > --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>

 > 

 > Thanks Stephen, I have a friend that is having success, in his TR-1, with VG's on the wings, I hadn't heard of anyone adding them to the elevator. Was you motivation to improve elevator authority in order to better control nose wheel touchdown or were you motivated by some other characteristic?

 > 

 > 

 > Jeff

 > KIS TR-1 #099

 > 

 > 

 > 

 > 

 > Read this topic online here:

 > 

 > http://forums.matronics.com/viewtopic.php?p=501019#501019

 > 

 > 

 > 

 > 

 > 

 > 

 > 

 > 

 > 

 

 

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jeffbudner

Joined: 20 Aug 2020
Posts: 18
Location: Rio Vista airport

Posted: Fri Mar 19, 2021 3:18 pm Post subject: Re: Stalling the TR-1

Thank you all for your responses. It's time for me to test the waters, find some altitude and slowly work my way into a stall. Your feedback is encouraging and much appreciated. I'm definitely considering VG's under the elevator.

Jeff

KIS TR-1 #099

gbrighton(at)skymesh.com.
Guest

Posted: Fri Mar 19, 2021 4:16 pm Post subject: Stalling the TR-1

Er .. Is that VG's .. under the 'Elevator' or 'Horizontal Stabilizer '

Graham

TR1 # 080



--------------------------------------------------

From: "jeffbudner" <jeffbudner(at)gmail.com>

Sent: Saturday, March 20, 2021 10:18 AM

To: <kis-list(at)matronics.com>

Subject: Re: Stalling the TR-1



 	  Quote: 	
		   



 Thank you all for your responses. It's time for me to test the waters, 

 find some altitude and slowly work my way into a stall. Your feedback is 

 encouraging and much appreciated. I'm definitely considering VG's under 

 the elevator.

 Jeff

 KIS TR-1 #099





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=501024#501024





 -- 

 This email has been checked for viruses by AVG.

 https://www.avg.com

GalinHdz

Joined: 08 Nov 2017
Posts: 150

Posted: Fri Mar 19, 2021 4:44 pm Post subject: Stalling the TR-1

Yea, that's what I meant.



On Fri, Mar 19, 2021 at 8:16 PM Graham Brighton <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)> wrote:



 	  Quote: 	
		  --> KIS-List message posted by: "Graham Brighton" <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)>

 

 Er .. Is that VG's .. under the 'Elevator' or 'Horizontal Stabilizer '

 Graham

 TR1 # 080

 

 --------------------------------------------------

 From: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>

 Sent: Saturday, March 20, 2021 10:18 AM

 To: <kis-list(at)matronics.com (kis-list(at)matronics.com)>

 Subject: Re: Stalling the TR-1

 

 > --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>

 >

 > Thank you all for your responses. It's time for me to test the waters, 

 > find some altitude and slowly work my way into a stall. Your feedback is 

 > encouraging and much appreciated. I'm definitely considering VG's under 

 > the elevator.

 >

 >

 > Jeff

 > KIS TR-1 #099

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p=501024#501024

 >

 >

 >

 >

 >

 >

 >

 >

 >

 >

 > -- 

 > This email has been checked for viruses by AVG.

 > https://www.avg.com

 > 

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fasilpereira

Joined: 17 Jul 2011
Posts: 86
Location: Brazil

Posted: Sat Mar 20, 2021 12:22 pm Post subject: Re: Stalling the TR-1

Hi Jeff!



Unfortunately I never had the chance to stall or to fly a TR-1, but for me, if it was properly built and if it is within the CG limits, it seems to be a docile aircraft with that rectangular and mid to low aspect ratio wing. The airfoil is also known for a predictable behavior.



If you are interested in expanding your envelope, begin with a good weight and balance. The aircraft should be configured from mid to FWD CG for the first stalls. As you expand the envelope, you can start thinking on AFT CG tests.



If you don’t have experience stalling high performance aircrafts, consider getting proper training or getting someone with more experience to test it for you.



Select an airspace suitable for testing and define your altitude limits to start the maneuver and to recover. Consider getting a parachute.



Begin the stall testing trimming at 1.3 to 1.5 Vs with Idle Power. Slow it down with elevator only at no more than 1 kt/s and recover at a safe speed. Pay attention to the aircraft tendencies and check controls (3 axis) effectiveness at  each 5 kt steps. Keep the ball centered! If all is ok, continue reducing the recover speed progressive up to full stall.



If you feel confident, explore stalls in turn and accelerated and aft CG too.



Good luck, keep safe and have fun!



Fabricio.

_________________
Fabricio Pereira
Engineer / Pilot

craneplanes(at)gmail.com
Guest

Posted: Mon Mar 22, 2021 6:08 am Post subject: Stalling the TR-1

Galin,

 

I really appreciate all you do for this group and all the advice you give us. On the VG’s, though, I need to respectfully disagree.

 

The purpose of vortex generators (VG’s) is to generate vortexes to “energize” the air and trip laminar flow air into turbulent flow. This allows the air to take a larger pressure differential before it separates (it can make a bigger, tighter bends before it separates and stalls). This is similar to the purpose of dimples on a golf ball.

 

In order to be effective in tripping laminar flow to turbulent flow the VGs must be 1) in laminar flow air and 2) be large enough to be out of the boundary layer. (The boundary layer is the area of the flow right next to the skin when the airflow is slowed down due to friction with the skin. It grows in thickness the further from the leading edges of the nose and wings.)

 

The horizontal stabs on the KR-1 and KR-4 are, like most single engine airplanes, in the propeller slip stream and at the back of the aircraft where the airflow is very turbulent. That means that VGs, especially the little ones (1” or so) are completely ineffective. Kent Pyle, whom I bought my TR-4 from and the world’s worst airplane builder (4.5 years to rebuild and redo everything he did due to unsafe building materials and techniques), had them on the airplane and I removed them.  Good news – Because the flow is so turbulent, the VGs probably don’t add any significant drag, so they really aren’t hurting anything except making it hard to clean the underside of the horizontal stab.

 

When I bought I flew my flying deathtrap 😊 (before realizing the need to rebuilt it), I simply could not hold the nose wheel off the ground, no matter how gently I touched the mains, and the nose would slam down. Following the advice of some TR-1 builders, I added 3” to the chord of the elevator to give me both more elevator and elevator trim authority (I couldn’t trim the airplane slower than about 90-knots). Three years later, while doing taxi testing, I discovered that the real reason the nose would slam down on landing was not because of a lack of elevator authority, but because the main gear were loose. (Kent used bolts that were too long and he shanked them out, so the main gear where just hanging loose from the airplane in flight and would “click” forward when landing!)  Point is – If you don’t have enough elevator authority, more elevator area is the cure, not VGs. (Note - I have not flown the “new” airplane yet, so I’m not sure what the impact of the additional elevator area is yet on a TR-4.)

 

(BTW, I’m a retired Navy test pilot and have a couple of degrees in Aero Engineering, specializing in aerodynamics. Just to establish a modicum of respectability with the group. 😊)

 

-Doug Crane

N302KM

KIS Cruiser TR-4

 

From: owner-kis-list-server(at)matronics.com <owner-kis-list-server(at)matronics.com> On Behalf Of Galin Hernandez

Sent: Friday, March 19, 2021 7:44 PM

To: kis-list(at)matronics.com

Subject: Re: Re: Stalling the TR-1



 

Yea, that's what I meant.



 

On Fri, Mar 19, 2021 at 8:16 PM Graham Brighton <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)> wrote:

 	  Quote: 	
		  

--> KIS-List message posted by: "Graham Brighton" <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)>



Er .. Is that VG's .. under the 'Elevator' or 'Horizontal Stabilizer '

Graham

TR1 # 080



--------------------------------------------------

From: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>

Sent: Saturday, March 20, 2021 10:18 AM

To: <kis-list(at)matronics.com (kis-list(at)matronics.com)>

Subject: Re: Stalling the TR-1



 	  Quote: 	
		   --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>



 Thank you all for your responses. It's time for me to test the waters, 

 find some altitude and slowly work my way into a stall. Your feedback is 

 encouraging and much appreciated. I'm definitely considering VG's under 

 the elevator.

 Jeff

 KIS TR-1 #099





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=501024#501024





 -- 

 This email has been checked for viruses by AVG.

 https://www.avg.com

 

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craneplanes(at)gmail.com
Guest

Posted: Mon Mar 22, 2021 6:32 am Post subject: Stalling the TR-1

Jeff,



Galin's advice is perfect on learning the stall characteristics of your airplane. As you do it, you'll learn to listen as your airplane "talks to you", and get the feeling and sounds as you approach a stall.



Another point - Stalls, in themselves, are not dangerous, especially in straight, "Hershey Bar" wings like we have. (Swept wings and abnormal, high performance wing shapes can be different.) The wings are designed to stall at the root (near the fuselage) before the tips, so the ailerons, being near the tips, are still effective, even when most of the wing is in stall. Also (and I'm not sure about the TR-1s, but on mine) the ailerons deflect upward much more than downward. This also helps reduce the possibility of a roll input causing the upward-going wing to stall and "snap" the airplane over (called a "snap stall").



The key is to have no yaw on the airplane. Keep the ball centered and use very little (or even better, no) ailerons to keep the plane level. All rudder, no stick. 



Keep these things in mind, and you can slow fly, slow stall, accelerated stall, deep stall it all day, and you'll be fine.  Practice your recovery (think "push, push" on the stick and throttle), and you'll be an ace in your airplane in no time. And, your landings will be terrific because you'll know how to feel the stall without looking at an airspeed during your landing flair and just kiss the mains on the runway. 😊  (BTW, slow flight and stalling is one of the first things I do when flying a new airplane. Really gives you a feel for it.)



-Doug Crane

N302KM

KIS Cruiser TR-4



--

GalinHdz

Joined: 08 Nov 2017
Posts: 150

Posted: Mon Mar 22, 2021 5:27 pm Post subject: Stalling the TR-1

Doug, All I know is that as I come to land, the nose drop with the VG's is much less than without them. Not completely gone but noticeably less. Maybe because at that point the engine is not generating much thrust so turbulence, as seen at the rear of the airplane is less, so they can make a difference. This is just me speculating on the reason for a noticeable difference in nose drop at touchdown speed.



To expand on this, when I replaced my aluminum Sensenich propeller with a CATTO composite propeller (20lbs less weight on the nose) the entire problem went away. The slight shift in CG made a huge difference. Now I can grease it in on almost every landing, something I couldn't consistently do before. But then, I am just an "average joe" pilot. <HUGE SMILE>

On Mon, Mar 22, 2021 at 10:09 AM <craneplanes(at)gmail.com (craneplanes(at)gmail.com)> wrote:



 	  Quote: 	
		  

Galin,

 

I really appreciate all you do for this group and all the advice you give us. On the VG’s, though, I need to respectfully disagree.

 

The purpose of vortex generators (VG’s) is to generate vortexes to “energize” the air and trip laminar flow air into turbulent flow. This allows the air to take a larger pressure differential before it separates (it can make a bigger, tighter bends before it separates and stalls). This is similar to the purpose of dimples on a golf ball.

 

In order to be effective in tripping laminar flow to turbulent flow the VGs must be 1) in laminar flow air and 2) be large enough to be out of the boundary layer. (The boundary layer is the area of the flow right next to the skin when the airflow is slowed down due to friction with the skin. It grows in thickness the further from the leading edges of the nose and wings.)

 

The horizontal stabs on the KR-1 and KR-4 are, like most single engine airplanes, in the propeller slip stream and at the back of the aircraft where the airflow is very turbulent. That means that VGs, especially the little ones (1” or so) are completely ineffective. Kent Pyle, whom I bought my TR-4 from and the world’s worst airplane builder (4.5 years to rebuild and redo everything he did due to unsafe building materials and techniques), had them on the airplane and I removed them.  Good news – Because the flow is so turbulent, the VGs probably don’t add any significant drag, so they really aren’t hurting anything except making it hard to clean the underside of the horizontal stab.

 

When I bought I flew my flying deathtrap 😊 (before realizing the need to rebuilt it), I simply could not hold the nose wheel off the ground, no matter how gently I touched the mains, and the nose would slam down. Following the advice of some TR-1 builders, I added 3” to the chord of the elevator to give me both more elevator and elevator trim authority (I couldn’t trim the airplane slower than about 90-knots). Three years later, while doing taxi testing, I discovered that the real reason the nose would slam down on landing was not because of a lack of elevator authority, but because the main gear were loose. (Kent used bolts that were too long and he shanked them out, so the main gear where just hanging loose from the airplane in flight and would “click” forward when landing!)  Point is – If you don’t have enough elevator authority, more elevator area is the cure, not VGs. (Note - I have not flown the “new” airplane yet, so I’m not sure what the impact of the additional elevator area is yet on a TR-4.)

 

(BTW, I’m a retired Navy test pilot and have a couple of degrees in Aero Engineering, specializing in aerodynamics. Just to establish a modicum of respectability with the group. 😊)

 

-Doug Crane

N302KM

KIS Cruiser TR-4

 

From: owner-kis-list-server(at)matronics.com (owner-kis-list-server(at)matronics.com) <owner-kis-list-server(at)matronics.com (owner-kis-list-server(at)matronics.com)> On Behalf Of Galin Hernandez

Sent: Friday, March 19, 2021 7:44 PM

To: kis-list(at)matronics.com (kis-list(at)matronics.com)

Subject: Re: Re: Stalling the TR-1



 

Yea, that's what I meant.



 

On Fri, Mar 19, 2021 at 8:16 PM Graham Brighton <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)> wrote:

 	  Quote: 	
		  

--> KIS-List message posted by: "Graham Brighton" <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)>



Er .. Is that VG's .. under the 'Elevator' or 'Horizontal Stabilizer '

Graham

TR1 # 080



--------------------------------------------------

From: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>

Sent: Saturday, March 20, 2021 10:18 AM

To: <kis-list(at)matronics.com (kis-list(at)matronics.com)>

Subject: Re: Stalling the TR-1



 	  Quote: 	
		   --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>



 Thank you all for your responses. It's time for me to test the waters, 

 find some altitude and slowly work my way into a stall. Your feedback is 

 encouraging and much appreciated. I'm definitely considering VG's under 

 the elevator.

 Jeff

 KIS TR-1 #099





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=501024#501024





 -- 

 This email has been checked for viruses by AVG.

 https://www.avg.com

 

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GalinHdz

Joined: 08 Nov 2017
Posts: 150

Posted: Mon Mar 22, 2021 6:15 pm Post subject: Stalling the TR-1

FWIW with the VG's I can approach to land at under 80KIAS with still some elevator authority and touchdown at under 65KIAS something I couldn't do before. But the change in propeller made the absolute biggest difference. 



On Mon, Mar 22, 2021 at 9:27 PM Galin Hernandez <galinhdz(at)gmail.com (galinhdz(at)gmail.com)> wrote:



 	  Quote: 	
		  Doug, All I know is that as I come to land, the nose drop with the VG's is much less than without them. Not completely gone but noticeably less. Maybe because at that point the engine is not generating much thrust so turbulence, as seen at the rear of the airplane is less, so they can make a difference. This is just me speculating on the reason for a noticeable difference in nose drop at touchdown speed.



To expand on this, when I replaced my aluminum Sensenich propeller with a CATTO composite propeller (20lbs less weight on the nose) the entire problem went away. The slight shift in CG made a huge difference. Now I can grease it in on almost every landing, something I couldn't consistently do before. But then, I am just an "average joe" pilot. <HUGE SMILE>

On Mon, Mar 22, 2021 at 10:09 AM <craneplanes(at)gmail.com (craneplanes(at)gmail.com)> wrote:



 	  Quote: 	
		  

Galin,

 

I really appreciate all you do for this group and all the advice you give us. On the VG’s, though, I need to respectfully disagree.

 

The purpose of vortex generators (VG’s) is to generate vortexes to “energize” the air and trip laminar flow air into turbulent flow. This allows the air to take a larger pressure differential before it separates (it can make a bigger, tighter bends before it separates and stalls). This is similar to the purpose of dimples on a golf ball.

 

In order to be effective in tripping laminar flow to turbulent flow the VGs must be 1) in laminar flow air and 2) be large enough to be out of the boundary layer. (The boundary layer is the area of the flow right next to the skin when the airflow is slowed down due to friction with the skin. It grows in thickness the further from the leading edges of the nose and wings.)

 

The horizontal stabs on the KR-1 and KR-4 are, like most single engine airplanes, in the propeller slip stream and at the back of the aircraft where the airflow is very turbulent. That means that VGs, especially the little ones (1” or so) are completely ineffective. Kent Pyle, whom I bought my TR-4 from and the world’s worst airplane builder (4.5 years to rebuild and redo everything he did due to unsafe building materials and techniques), had them on the airplane and I removed them.  Good news – Because the flow is so turbulent, the VGs probably don’t add any significant drag, so they really aren’t hurting anything except making it hard to clean the underside of the horizontal stab.

 

When I bought I flew my flying deathtrap 😊 (before realizing the need to rebuilt it), I simply could not hold the nose wheel off the ground, no matter how gently I touched the mains, and the nose would slam down. Following the advice of some TR-1 builders, I added 3” to the chord of the elevator to give me both more elevator and elevator trim authority (I couldn’t trim the airplane slower than about 90-knots). Three years later, while doing taxi testing, I discovered that the real reason the nose would slam down on landing was not because of a lack of elevator authority, but because the main gear were loose. (Kent used bolts that were too long and he shanked them out, so the main gear where just hanging loose from the airplane in flight and would “click” forward when landing!)  Point is – If you don’t have enough elevator authority, more elevator area is the cure, not VGs. (Note - I have not flown the “new” airplane yet, so I’m not sure what the impact of the additional elevator area is yet on a TR-4.)

 

(BTW, I’m a retired Navy test pilot and have a couple of degrees in Aero Engineering, specializing in aerodynamics. Just to establish a modicum of respectability with the group. 😊)

 

-Doug Crane

N302KM

KIS Cruiser TR-4

 

From: owner-kis-list-server(at)matronics.com (owner-kis-list-server(at)matronics.com) <owner-kis-list-server(at)matronics.com (owner-kis-list-server(at)matronics.com)> On Behalf Of Galin Hernandez

Sent: Friday, March 19, 2021 7:44 PM

To: kis-list(at)matronics.com (kis-list(at)matronics.com)

Subject: Re: KIS-List: Re: Stalling the TR-1



 

Yea, that's what I meant.



 

On Fri, Mar 19, 2021 at 8:16 PM Graham Brighton <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)> wrote:

 	  Quote: 	
		  

--> KIS-List message posted by: "Graham Brighton" <gbrighton(at)skymesh.com.au (gbrighton(at)skymesh.com.au)>



Er .. Is that VG's .. under the 'Elevator' or 'Horizontal Stabilizer '

Graham

TR1 # 080



--------------------------------------------------

From: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>

Sent: Saturday, March 20, 2021 10:18 AM

To: <kis-list(at)matronics.com (kis-list(at)matronics.com)>

Subject: Re: Stalling the TR-1



 	  Quote: 	
		   --> KIS-List message posted by: "jeffbudner" <jeffbudner(at)gmail.com (jeffbudner(at)gmail.com)>



 Thank you all for your responses. It's time for me to test the waters, 

 find some altitude and slowly work my way into a stall. Your feedback is 

 encouraging and much appreciated. I'm definitely considering VG's under 

 the elevator.

 Jeff

 KIS TR-1 #099





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 http://forums.matronics.com/viewtopic.php?p=501024#501024





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