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SV: SV: Re: KIS IT-1 Aerodynamics

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hans-chr.erstad(at)c2i.ne
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Posted: Mon Jul 05, 2010 2:23 pm Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

Thanks for comments Mark



I will do the take off as you explain the next time I fly, and report back





You mentioned "More to do with science and engineering methods". I have

encosed a NACA report I found when googling for some scientific material on

the subject, after I first met Julian, and he told about his modification.

Interresting reading, both from an scientific and  historical, point of

view! Many things in our world have changed since that report were made, but

the laws of physics have not changed? 



I have not experienced any loss of elevator authority, but feel that an

approach at lowest speed needs a lot of adjustment in pitch. But close to

ground there is almost always some turbulence anyway. 



But making control input while flying is not a problem - it is what piloting

is about 



Regards, Hans Christian



-----Opprinnelig melding-----

Fra: owner-kis-list-server(at)matronics.com

[mailto:owner-kis-list-server(at)matronics.com] På vegne av Mark Kettering

Sendt: 5. juli 2010 20:18

Til: kis-list(at)matronics.com

Emne: Re: SV: Re: KIS IT-1 Aerodynamics






Hello Hans,



 	  Quote: 	
		  I have flown my KIS 1 for 10 years now, and I agree with 'OC' comments 

about the handling with respect to difficulties making consistent 

landings and keeping the nose wheel up.


	


I have flown a TR1 with the main gear in the stock position and with that

aircraft I also had the same problems.  So I made some calculations and

found out that the stock main gear location was too far aft.  On my TR1 I

then moved it forward and fully eliminated not only this problem on my

aircraft but also the takeoff tendency to over rotate.  When flying with

Rich and watching the stick I noted that he had to pull way back to rotate

then quickly release this back force and movement to prevent over rotation

on lift off.



 	  Quote: 	
		  About the wing/fuselage fairing.  I have meet Julian several times at 

fly-in.  He told that the fairing modification made the landings with a 

low approach speed a lot easier. Why not believe his experience? I 

think he is the only one to make the modification, and having 

experiencd what difference it makes.  I have fairing modification on my 

to-do list. But I may never come to that item on my list, as I feel the 

landings are still OK, and I do not operate from runways shorter than 

800 meters. I usually keep a little power on in the flare.


	


Well, I am not a believer!  But that has little to do with Julian's

experiences.  More to do with science and engineering methods.  At some

point with more data I may agree that the elevator loses authority due to

wing fuselage junction separation. At this point I am waiting on seeing the

video for myself.  The one still picture I have seen does not seem to

support the conclusion that the wing fuselage junction is causing separation

of flow over the tail.  I also never have a sudden loss or any loss of

elevator authority with my aircraft at any time and I have the stock wing

root fairings so this data also does not seem to support that conclusion.



But this is not to say that Julian did not have this problem.  Maybe his

plane is slightly different than mine.  Maybe my more poor (or maybe better)

fit of my parts in this area prevented a problem that his plane had.  Who

knows?



But I do do know the stock main gear location is too far aft relative to the

CG (range) location.  I also know that angling the gear forward (moving the

gear contact point forward) reduces the hard nose let down at all CG

locations and cures the tendency to over rotate.



Next time you fly please try this for me but be very careful and let me know

what happens!  As you pull back to rotate just hold the stick in the same

location and fly off the runway.  This is how a good handling aircraft

should takeoff.  It should not need pilot input beyond a steady back

pressure.  You should not need to release or push forward.  The plane should

literally "fly itself" off the runway.  But if you do this in the TR1 with

the main gear in the stock location you will over rotate and need to move

the stick forward.  Or you will stall and maybe worse.



Also please keep in mind that the gear location is very easy to change.



Thanks,

Mark

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mantafs(at)earthlink.net
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Posted: Mon Jul 05, 2010 7:47 pm Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

Hi Hans,



That is a very interesting NACA report.  I think that specific aircraft design had some major issues.  Plus the airfoil used has a major issue of it's own.  For example the airfoil has an initial stall angle of just 8.5 degrees, right about where the tail starts to be less effective according to the report.  Of course when the wing stalls then there is less down wash on the tail so there is less down force.  But most engineers today think of this as a very good thing since it helps act to reduce the likely hood of a stall.  If the main wing is starting to stall, then maybe there should be less down force in the tail so the plane starts to pitch down to keep more of the main wing from stalling.



They also talk as if the tail buffeting is a bad thing.  Of course tail flutter is but that is not at all the same as buffeting.  Production aircraft today are required to have some sort of tail buffeting to warn of a stall.  Planes that do not have this "stall indication" are then required to have stick shakers and/or stall horns.  If you look at some production aircraft they have main wing leading edge wedges near the root to make buffeting prestall to meet this requirement.



I am a big fan of the old NACA reports.  I spent one summer at NASA reading a bunch of them.  Many of the old reports are very applicable to our small aircraft.  But at times you need to be very careful applying the information in them since at times there is a difference in goal, way of thinking or original conditions to what we have today.  For example this report did not address handling qualities on any way.  Yes, maybe you could keep the root from stalling first.  But do you really want to?  I prefer the root to stall before the center and tip since I do not like for the plane to roll into a spin when it stalls. Yes, you can eliminate tail buffeting but do you want to remove the stick shake that warns you of the impending stall?  Some airfoils like the NACA M6 have preliminary and secondary stall and this can greatly effect the data but then is this data applicable to our airfoil?



In any case, I think this supports my original theory in that all we are really seeing is the start of the main wing stall and it is starting at the root.  Large radius fairings may reduce the local Cl at the root and then this could delay the stall at the root.  But the wing will still stall.



Thanks,

Mark

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ftyoder(at)yoderbuilt.com
Guest

Posted: Mon Jul 05, 2010 9:08 pm Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

Hello Mark,



I was thinking that this wing would not be beginning to stall at the 80 to 

65 mph short final to flair, that I think most of the reporters are 

indicating. Our wings are level with a low pitch angle. I understand that it 

is better to have the stall begin at the root but I thought it would be at 

below 65mph for the TR-1, is this thinking wrong?



Thanks,

Tim

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hans-chr.erstad(at)c2i.ne
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Posted: Tue Jul 06, 2010 9:04 am Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

Tim



My Numbers:

Main gear axle: STA 73.6 (my construction manual says 73.5, so meybe I did

not follow it 100% after all 

Nose gear axle: STA 21.2 

Firewall rear face (ref point): STA 32

(73.6-32=41.6)



See also http://home.c2i.net/h-erstad/  Weight&Balance report



Hans Christian



-----Opprinnelig melding-----

Fra: owner-kis-list-server(at)matronics.com

[mailto:owner-kis-list-server(at)matronics.com] På vegne av F. Tim Yoder

Sendt: 6. juli 2010 00:52

Til: kis-list(at)matronics.com

Emne: Re: SV: Re: KIS IT-1 Aerodynamics






Mark, 'OC' and all,



My gear dimensions are as follows;

 Main gear axle center line to firewall is 42 1/8"

   "        "      "        "       "   " nose gear axle center line 53"



I would be interested to see your numbers.



In retrospect, I do have to watch and may have to increase stick pressure in

order to keep the nose gear off the runway. But I do have plenty of elevator

authority to do that.



Julian's plane was a tail dragger (conventional) I think. He was trying to

give it STOL qualities, an oxymoron I think. I forget what he built to

replace the KIS, I think it is a high wing with better STOL qualities.



Mark, I am in annual now, but I will try and report on your take off

procedure. That is if I don't stall, crash, and burn!



Also, maybe it would be helpful to confirm final approach and touch down

speeds from the GPS, if available, to confirm the accuracy of our different

pitot systems at slow speeds. I you are flying alone, it might be safest to

do this at altitude in a practice area.



'OC', maybe Mark and Rich are just better pilots than you and I because I

use your technique for more consistent landings.



Oh, Mark and 'OC' what was the thickness of your main gear shims? Are they

fiberglass or aluminum or???



Tim



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mantafs(at)earthlink.net
Guest

Posted: Tue Jul 06, 2010 9:14 am Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

Hello Tim,



At gross weight and with 20 degrees of flaps the theoretical calculated stall with the airfoil on the TR1 would be 60.5 mph.  This number is using the standard definition for the wing area, length X cord.  Since some of the "area" is inside the fuselage the actual usable area (area generating lift) is slightly less so making a ball park adjustment I would guess actual stall speed would be about 63 mph.  This does also not take into account the added "weight" from the tail down force that of course the wing also needs to support.  Of course when we build the planes they are not perfect or the same so maybe your stall is slightly different and generally higher.  So, 65 mph is not at all far off from stall.  And as someone recently implied, the pitot airspeed may not be accurate especially at low speeds.



At gross the TR1 is not at all a STOL type aircraft.  The wing is just too small and short.  But it is a good all around performer with a fair cruise speed and a fair landing speed.



Thanks,

Mark

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jconners(at)dot.state.nv.
Guest

Posted: Tue Jul 06, 2010 9:26 am Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

My experiences flying N94K (KIS TR-1 with Lycoming O-235 L2C) at slow speeds at high altitudes (8000-14500 MSL) and full fuel with pilot only...the aircraft does not stall at 35 knots but the resulting extreme low tail attitude prevents landing at such speeds.



What are the recorded slow flight speeds being experienced by other TR-1 pilots?



Jer



Jerry Conners, PE

Civil Engineer

Nevada Department of Transportation

310 Galletti Way

Sparks, Nevada 89431

775-834-8363 (voice mail)

jconners(at)dot.state.nv.us



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richard_trickel(at)yahoo.
Guest

Posted: Tue Jul 06, 2010 9:42 am Post subject: SV: SV: Re: KIS IT-1 Aerodynamics

Hi Jerry

 Thanks for logging in.  You say the plane stalls 35 Knots so I´m guessing that is indicated.  Have you tried to compare with a gps in different directions to compensate for the wind.. Your number is very low.

 Rich



--- On Tue, 7/6/10, Conners, Jerry L <jconners(at)dot.state.nv.us> wrote:



 [quote]

From: Conners, Jerry L <jconners(at)dot.state.nv.us>

Subject: RE: SV: SV: Re: KIS IT-1 Aerodynamics

To: kis-list(at)matronics.com

Date: Tuesday, July 6, 2010, 5:21 PM



 --> KIS-List message posted by: "Conners, Jerry L" <jconners(at)dot.state.nv.us (jconners(at)dot.state.nv.us)>



My experiences flying N94K (KIS TR-1 with Lycoming O-235 L2C) at slow speeds at high altitudes (8000-14500 MSL) and full fuel with pilot only...the aircraft does not stall at 35 knots but the resulting extreme low tail attitude prevents landing at such speeds.



What are the recorded slow flight speeds being experienced by other TR-1 pilots?



Jer



Jerry Conners, PE

Civil Engineer

Nevada Department of Transportation

310 Galletti Way

Sparks, Nevada 89431

775-834-8363 (voice mail)

jconners(at)dot.state.nv.us (jconners(at)dot.state.nv.us)



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