Today's Message Index:
----------------------
1. 04:06 AM - Barrel Rolls (Fox5flyer)
2. 04:15 AM - Re: Re: Wing strut fairing tests (AlbertaIV@aol.com)
3. 07:21 AM - Re: Re: Fuel stop in Illinois (kurt schrader)
4. 07:33 AM - Re: Re: Fuel stop in Illinois (Aerobatics@aol.com)
5. 08:16 AM - Re: Re: Fuel stop in Illinois (Ron)
6. 12:46 PM - Re: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight testing (Stu Bryant)
7. 02:44 PM - Re: Re: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight testing (Brian Peck)
8. 07:41 PM - Re: Re: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight testing (Lowell Fitt)
9. 08:25 PM - Re: Re: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight (Stu Bryant)
10. 08:49 PM - Re: Re: Fuel stop in Illinois (Bob Unternaehrer)
11. 09:17 PM - Re: Re: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight (Stu Bryant)
12. 09:57 PM - Re: VG's and the testing process (kurt schrader)
13. 10:28 PM - VG's and their testing. (Clint Bazzill)
14. 10:46 PM - Re: VG's and the testing process (jimshumaker)
15. 11:01 PM - Re: Re: KitFox N210F "HEAVY" (kurt schrader)
16. 11:07 PM - Re: VG's and their testing. (kurt schrader)
17. 11:11 PM - Re: VG's and the testing process (kurt schrader)
Message 1
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--> Kitfox-List message posted by: "Fox5flyer" <morid@northland.lib.mi.us>
Anybody out there done barrel rolls with their Fox? I need the step by step
procedure including entry speed. My prop is geared so is counter rotating.
Does this mean the rolls need to be to the right?
How about loops?
And yes, I'm getting a checkout first.
Darrel
S5
Message 2
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| Subject: | Re: RE: Wing strut fairing tests |
--> Kitfox-List message posted by: AlbertaIV@aol.com
<<
Does that make any sense? I think an extra NACA
opening in the scoop behind the radiator is the best
image I can offer.
Kurt S. >>
Yes, would need a picture to grasp the whole idea. Keep plugging away.
Don Smythe
N-998DS Classic IV W/ 582
Message 3
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| Subject: | Re: RE: Fuel stop in Illinois |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Well gang, I expect to sign off my plane as testing
completed Monday. Need to test 2 more days worth.
Next week I plan to fly my first X-country to
Wisconsin to show my ailing dad and take him up. I'll
need a auto gas fuel stop in Illinois both ways.
Anyone know of a good place in the general area
between Bloomington and Kankakee? That is about 1/2
way for me. Anyone live there and want to visit?
Kurt S. S-5 almost a real plane!
_______________________________
Declare Yourself - Register online to vote today!
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| Subject: | Re: RE: Fuel stop in Illinois |
--> Kitfox-List message posted by: Aerobatics@aol.com
How about Paxton? they have fule at a good price 3,400 foot N/S Paved...
Ill zip over weather and time permiting... its only 18 Miles west of me..
Dave
KF2
Message 5
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| Subject: | Re: RE: Fuel stop in Illinois |
--> Kitfox-List message posted by: "Ron" <rliebmann@comcast.net>
Hey Kurt,
If ya can get to Schaumburg Regional Airport, 06C, I can bring autogas
to fill ya up..........Its just west of O'Hare and where I keep my Fox.
Ron N55KF
> Well gang, I expect to sign off my plane as testing
> completed Monday. Need to test 2 more days worth.
> Next week I plan to fly my first X-country to
> Wisconsin to show my ailing dad and take him up. I'll
> need a auto gas fuel stop in Illinois both ways.
> Anyone know of a good place in the general area
> between Bloomington and Kankakee? That is about 1/2
> way for me. Anyone live there and want to visit?
>
> Kurt S. S-5 almost a real plane!
>
>
Message 6
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| Subject: | RE: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight testing |
--> Kitfox-List message posted by: "Stu Bryant" <s.j.bryant@sbcglobal.net>
Lowell & Kurt,
I mostly agree with you, Lowell, except on one point. I am not so convinced
of is that IA necessarily tell the whole story if the error factor at
various AOA's is not well mapped. There may be a point at some relatively
extreme AOA where the AI becomes so far off- because of pitot AOA- that you
no longer are getting useful information. If that point happens to be right
in the difference between before and after with VG's, then all bets are off.
It seems to me we have little way to determine whether an indicated airspeed
still has much meaning below a certain point or where that point even lies.
Yes, Kurt's pitot tube was at a constant angle- but only in relation to the
wing. Not in relation to the air movement which would be more useful IMO.
This is why there is an error factor at high AOA's in the first place. As
the angle increases the pitot tube begins to slightly more resemble a static
port since the angle of impact of the air molecules becomes so much less
direct. Isn't this why engineers place additional pitot tubes, big ugly
ones- when they work at expanding the flight envelopes of a given new
design? And isn't it true that the presence of the airplane itself
introduces potential errors (which are hopefully corrected for in the final
design)? I could well be all wet here in this particular situation, but how
do we know for sure? It is well enough documented that many pitot systems do
not work well beyond a certain point. If they effectively flatline at some
AOA, then they cease to be a useful indication. You might even have an
improvement which cannot be measured as a result. Or even what appears to be
an improvement but isn't. Kurt, you have an excellent instrument. I'm not
doubting your AI, but maybe pitot tube given the scenario?
Kurt said, "Whatever ASI error applied to "no VG's" applied to any VG
pattern I used." Maybe. But only if the stall happened at the same exact AOA
with and without (unless your pitot error has been already proven to be
negligible by some external reference) And aren't these VG things supposed
to change the AOA of stall? I thought that was precisely why people buy
them. Kurt, your protocol seems flawless. I just wonder if you compared the
GPS at the most extreme AOA's for each config? Not that I'd have been able
to!
Lowell, the difficulties in using a GPS are duly noted, but what other
option do we have for external validation of the data?
Sorry to have used so many words to make my point. Concise is better, but
that is not a strength of mine.
Stu
Message 7
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| Subject: | Re: RE: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight |
testing
--> Kitfox-List message posted by: Brian Peck <u2drvr@dslextreme.com>
Let me add my $.02...
When a pitot tube is at an angle to the relative wind, there is very
little error in the reading up to about 30 degrees. Past this, the
error gets very large. The largest errors in a pitot-static system are
usually on the static side and this is why you often see "big ugly"
pitot tubes on test aircraft...they also have static ports on the tube
and usually alpha and beta vanes as well (to measure AOA and sideslip).
The other common method to reduce static error is a trailing cone,
which is a tube that measures static pressure well outside the flow
field of the aircraft.
Using GPS to determine stall speeds is problematic because it gives you
groundspeed. You then have to do it in different direction and average
the results to correct for wind to get TAS. Then correct for temp and
PA to get calibrated airspeed, then guess at installation error to get
indicated airspeed. I believe Kurt said that his system was check using
test equipment to IFR standards and I believe that is at least as good
as using GPS if not better.
ASI errors will not be significantly different with small changes in
AOA, so I believe Kurt's methodology and data to be valid.
Brian Peck
U-2 Test Pilot
Kitfox 5, IO-240
On Oct 9, 2004, at 12:49 PM, Stu Bryant wrote:
> --> Kitfox-List message posted by: "Stu Bryant"
> <s.j.bryant@sbcglobal.net>
>
>
> Lowell & Kurt,
>
> I mostly agree with you, Lowell, except on one point. I am not so
> convinced
> of is that IA necessarily tell the whole story if the error factor at
> various AOA's is not well mapped. There may be a point at some
> relatively
> extreme AOA where the AI becomes so far off- because of pitot AOA-
> that you
> no longer are getting useful information. If that point happens to be
> right
> in the difference between before and after with VG's, then all bets
> are off.
> It seems to me we have little way to determine whether an indicated
> airspeed
> still has much meaning below a certain point or where that point even
> lies.
> Yes, Kurt's pitot tube was at a constant angle- but only in relation
> to the
> wing. Not in relation to the air movement which would be more useful
> IMO.
> This is why there is an error factor at high AOA's in the first place.
> As
> the angle increases the pitot tube begins to slightly more resemble a
> static
> port since the angle of impact of the air molecules becomes so much
> less
> direct. Isn't this why engineers place additional pitot tubes, big ugly
> ones- when they work at expanding the flight envelopes of a given new
> design? And isn't it true that the presence of the airplane itself
> introduces potential errors (which are hopefully corrected for in the
> final
> design)? I could well be all wet here in this particular situation,
> but how
> do we know for sure? It is well enough documented that many pitot
> systems do
> not work well beyond a certain point. If they effectively flatline at
> some
> AOA, then they cease to be a useful indication. You might even have an
> improvement which cannot be measured as a result. Or even what appears
> to be
> an improvement but isn't. Kurt, you have an excellent instrument. I'm
> not
> doubting your AI, but maybe pitot tube given the scenario?
>
> Kurt said, "Whatever ASI error applied to "no VG's" applied to any VG
> pattern I used." Maybe. But only if the stall happened at the same
> exact AOA
> with and without (unless your pitot error has been already proven to be
> negligible by some external reference) And aren't these VG things
> supposed
> to change the AOA of stall? I thought that was precisely why people buy
> them. Kurt, your protocol seems flawless. I just wonder if you
> compared the
> GPS at the most extreme AOA's for each config? Not that I'd have been
> able
> to!
>
> Lowell, the difficulties in using a GPS are duly noted, but what other
> option do we have for external validation of the data?
>
> Sorry to have used so many words to make my point. Concise is better,
> but
> that is not a strength of mine.
>
> Stu
>
>
> _-
> =======================================================================
> _-
> =======================================================================
> _-
> =======================================================================
> _-
> =======================================================================
> >
>
>
Message 8
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| Subject: | Re: RE: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight |
testing
--> Kitfox-List message posted by: "Lowell Fitt" <lcfitt@inreach.com>
----- Original Message -----
From: "Stu Bryant" <s.j.bryant@sbcglobal.net>
Subject: Kitfox-List: RE: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight
testing
> --> Kitfox-List message posted by: "Stu Bryant" <s.j.bryant@sbcglobal.net>
>
>
> Lowell & Kurt,
(snip)
> As the angle increases the pitot tube begins to slightly more resemble a
static
> port since the angle of impact of the air molecules becomes so much less
> direct.
Can't respond to the engineers ugly pitot tubes, but if the angle of attack
was sufficient that the pitot tube was beginning to resemble a static port,
then the error would be an apparent drop in airspeed . This is exactly the
argument John Larson was making when he attributed most apparent VG stall
speed improvement in our airplanes, to pitot tube error due to angle of
attack.
(snip)
> Kurt said, "Whatever ASI error applied to "no VG's" applied to any VG
> pattern I used." Maybe. But only if the stall happened at the same exact
AOA
> with and without (unless your pitot error has been already proven to be
> negligible by some external reference) And aren't these VG things supposed
> to change the AOA of stall? I thought that was precisely why people buy
> them.
Exactly what John suggested. If the pitot tube error came in to play, Kurt
would have had an "apparent" reduction in stall speed due to increased angle
of attack even though there might have been no reduction in actual airspeed
at all - he didn't - at least not more than the +,- 2 kts he mentoined.
Brian suggested that as pitot tube error comes into play the error grows as
angle of attack increases, so if Kurt was in a zone of error when clean,
then as the VGs allowed for increased angle of attack, the error - lower
reading - would be more pronounced.
Since Kurts clean stall numbers were consistant with previous readings and
are consistant with numerous other flying Kitfoxes, I am comfortable with
them and are pretty much persuaded that VGs are not helping his airplane.
It would be an interesting addition to Kurt's work to see if the effect of
VGs were different in a liter loaded wing.
(snip)
> Lowell, the difficulties in using a GPS are duly noted, but what other
> option do we have for external validation of the data?
I hate to say this, but if positive data is so hard to find, it might
suggest that it is just not there, at least with our airplanes. If the
poositive data was in the area of 12 kts. as some claim, I can't imagine it
would be hidden by pitot tube error. 5 kts. maybe, but I doubt it. Less
than 5 kts? Is it signifificant enough to try to find it.
Lowell
> Sorry to have used so many words to make my point. Concise is better, but
> that is not a strength of mine.
>
> Stu
>
>
Message 9
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| Subject: | Re: RE: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight |
--> Kitfox-List message posted by: "Stu Bryant" <s.j.bryant@sbcglobal.net>
Excellent answer, Brian. That does help connect the dots for me.
So how close to 30 deg AOA would the typical Kitfox ever get during a stall?
30 deg is a lot, would have to be a departure (power on) stall I would think
to get anywhere near that. I'll be honest, while I am thoroughly infatuated
with Kitfoxes, all my time (including tail wheel) has been in Cessna's. Not
that I wouldn't love to try on a KF, Champ/Citabria, or Cub for size.
Stu
Message 10
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| Subject: | Re: RE: Fuel stop in Illinois |
--> Kitfox-List message posted by: "Bob Unternaehrer" <shilohcom@c-magic.com>
How about Erie Airpark, 3H5 near the quad cities. They only have premium
auto and mixed 2 cycle fuel. Bob U.
----- Original Message -----
From: "kurt schrader" <smokey_bear_40220@yahoo.com>
Subject: Re: Kitfox-List: RE: Fuel stop in Illinois
> --> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
>
> Well gang, I expect to sign off my plane as testing
> completed Monday. Need to test 2 more days worth.
> Next week I plan to fly my first X-country to
> Wisconsin to show my ailing dad and take him up. I'll
> need a auto gas fuel stop in Illinois both ways.
> Anyone know of a good place in the general area
> between Bloomington and Kankakee? That is about 1/2
> way for me. Anyone live there and want to visit?
>
> Kurt S. S-5 almost a real plane!
>
>
> _______________________________
> Declare Yourself - Register online to vote today!
> http://vote.yahoo.com
>
>
> ---
>
>
---
Message 11
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| Subject: | RE: RE: Kitfox-List Digest: 17 Msgs - 10/08/04 VG flight |
--> Kitfox-List message posted by: "Stu Bryant" <s.j.bryant@sbcglobal.net>
Lowel,
You are very knowledgeable about this, sir. Actually all of you
participating in this thread are.
I have no agenda one way or the other, and frankly do not disagree with any
of the conclusions, either. I wasn't sure whether any potential skewing of
the data by this theoretical dilemma would be positive or negative. I was
merely concerned that there was potential for a skewing which might be
difficult to detect. I just thought I saw an area where another
consideration might potentially might be useful. Evidently with the given
particulars this was not helpful. - OK, I accept that.
You said "...so if Kurt was in a zone of error when clean,
then as the VGs allowed for increased angle of attack, the error - lower
reading - would be more pronounced."
Yes I agree completely, just still can't see how we would necessarily
recognize this with the data presented alone- without an external
validation- IF we slipped into that error range where the AOA was
sufficiently different (between the before & after scenario) to introduce an
error of any significance. While I don't know conclusively, I strongly
suspect that this remains a merely theoretical issue which does not come
into play here at all. This, of course, would be a very good thing. :-) I
agree that Kurt has done an outstanding job with this project, and believe
his conclusion to be valid.
I've beat this horse more than enough now. Hope I didn't ruffle any
feathers- that certainly was not my intent. Personally, I found this to be a
stimulating discussion.
Stu
Message 12
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| Subject: | Re: VG's and the testing process |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Stu and everyone,
I also think this was very stimulating and like the
scientific mentality to challenge the process and
conclusions before accepting them. To me that process
is bigger and worth more than these single results
themselves. I applaud the challengers as those with
courage enough to promote this necessary corrective
proceedure.
But I would especially like to find a cause and a cure
for not achieving a slower stall, and wish I had that
over any pride of authorship. I don't think we found
one yet. Darn...
A few points to make to add to this:
A. There was no significant difference in indicated
stall speeds. If a greater AOA was achieved, there
should have been some indicated difference, and pitot
error could then exerate that. I think the angles
were always the same for each flap setting no matter
what VG's were used, +/- a degree.
B. One solution to pitot error is to mount the pitot
tube at a median downward angle so that it is in line
with the slip stream half way between zero AOA and
stall. That would produce an error of very small size
on either end of the AOA/speed range. I think that
the error was in fact small at the AOA's I achieved.
I suspect that only my power-on stall got near 20
degrees and the others were around 16.
C. But I have the silver bullet - TA DA - an AOA
probe, thanks to Elbie and RiteAngle. It points into
the slipstream and measures AOA directly. For all of
my stalls tests however, I turned it off so as not to
distract me or cause "stall anticipation". But for
later testing I can enable it and have it "report"
differences in stall angle, if any. Expect that next
year though. Too much to do for now. The VG testing
took 6 days I can't make up. I had hoped it would
work in a day or 2.
Thanks for all the input. I hope someone finds a
better answer.
Kurt S. S-5/NSI turbo
--- Stu Bryant <s.j.bryant@sbcglobal.net> wrote:
> Lowel,
> You are very knowledgeable about this, sir. Actually
> all of you participating in this thread are.
>
> I have no agenda one way or the other, and frankly
> do not disagree with any
> of the conclusions, either. I wasn't sure whether
> any potential skewing of
> the data by this theoretical dilemma would be
> positive or negative. I was
> merely concerned that there was potential for a
> skewing which might be
> difficult to detect. I just thought I saw an area
> where another
> consideration might potentially might be useful.
> Evidently with the given
> particulars this was not helpful. - OK, I accept
> that.
>
>
> You said "...so if Kurt was in a zone of error when
> clean,
> then as the VGs allowed for increased angle of
> attack, the error - lower
> reading - would be more pronounced."
>
> Yes I agree completely, just still can't see how we
> would necessarily
> recognize this with the data presented alone-
> without an external
> validation- IF we slipped into that error range
> where the AOA was
> sufficiently different (between the before & after
> scenario) to introduce an
> error of any significance. While I don't know
> conclusively, I strongly
> suspect that this remains a merely theoretical issue
> which does not come
> into play here at all. This, of course, would be a
> very good thing. :-) I
> agree that Kurt has done an outstanding job with
> this project, and believe
> his conclusion to be valid.
>
> I've beat this horse more than enough now. Hope I
> didn't ruffle any
> feathers- that certainly was not my intent.
> Personally, I found this to be a
> stimulating discussion.
>
> Stu
__________________________________
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| Subject: | VG's and their testing. |
--> Kitfox-List message posted by: "Clint Bazzill" <clint_bazzill@hotmail.com>
I have been reading the results of Kurt's VG testing with interest. There are several
questions that I didn't see answered. One, Kurt is flying a Model V with
a subaru engine. What is the CG location and are the wings swept forward as
most heavy Kitfoxes are. A forward CG could explain the aircraft not being able
to spin to the right. Some thought. Clint
Message 14
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| Subject: | Re: VG's and the testing process |
--> Kitfox-List message posted by: "jimshumaker" <jimshumaker@sbcglobal.net>
Hi Kurt
Thanks for filling us in on your VG tests. I have a different wing and so
my setup may not work for you. I did not get a reasonable improvement in
stall until I moved the VG's to 3 inches from the leading edge. You might
want to try that next year. Like you, I would not bother keeping them on
unless there was enough improvement to make enough difference to put up with
their drawbacks.
Jim Shumaker.
----- Original Message -----
From: "kurt schrader" <smokey_bear_40220@yahoo.com>
Subject: Re: Kitfox-List: VG's and the testing process
> --> Kitfox-List message posted by: kurt schrader
<smokey_bear_40220@yahoo.com>
>
> Stu and everyone,
>
> I also think this was very stimulating and like the
> scientific mentality to challenge the process and
> conclusions before accepting them. To me that process
> is bigger and worth more than these single results
> themselves. I applaud the challengers as those with
> courage enough to promote this necessary corrective
> proceedure.
>
> But I would especially like to find a cause and a cure
> for not achieving a slower stall, and wish I had that
> over any pride of authorship. I don't think we found
> one yet. Darn...
>
> A few points to make to add to this:
>
> A. There was no significant difference in indicated
> stall speeds. If a greater AOA was achieved, there
> should have been some indicated difference, and pitot
> error could then exerate that. I think the angles
> were always the same for each flap setting no matter
> what VG's were used, +/- a degree.
>
> B. One solution to pitot error is to mount the pitot
> tube at a median downward angle so that it is in line
> with the slip stream half way between zero AOA and
> stall. That would produce an error of very small size
> on either end of the AOA/speed range. I think that
> the error was in fact small at the AOA's I achieved.
> I suspect that only my power-on stall got near 20
> degrees and the others were around 16.
>
> C. But I have the silver bullet - TA DA - an AOA
> probe, thanks to Elbie and RiteAngle. It points into
> the slipstream and measures AOA directly. For all of
> my stalls tests however, I turned it off so as not to
> distract me or cause "stall anticipation". But for
> later testing I can enable it and have it "report"
> differences in stall angle, if any. Expect that next
> year though. Too much to do for now. The VG testing
> took 6 days I can't make up. I had hoped it would
> work in a day or 2.
>
> Thanks for all the input. I hope someone finds a
> better answer.
>
> Kurt S. S-5/NSI turbo
>
> --- Stu Bryant <s.j.bryant@sbcglobal.net> wrote:
>
> > Lowel,
> > You are very knowledgeable about this, sir. Actually
> > all of you participating in this thread are.
> >
> > I have no agenda one way or the other, and frankly
> > do not disagree with any
> > of the conclusions, either. I wasn't sure whether
> > any potential skewing of
> > the data by this theoretical dilemma would be
> > positive or negative. I was
> > merely concerned that there was potential for a
> > skewing which might be
> > difficult to detect. I just thought I saw an area
> > where another
> > consideration might potentially might be useful.
> > Evidently with the given
> > particulars this was not helpful. - OK, I accept
> > that.
> >
> >
> > You said "...so if Kurt was in a zone of error when
> > clean,
> > then as the VGs allowed for increased angle of
> > attack, the error - lower
> > reading - would be more pronounced."
> >
> > Yes I agree completely, just still can't see how we
> > would necessarily
> > recognize this with the data presented alone-
> > without an external
> > validation- IF we slipped into that error range
> > where the AOA was
> > sufficiently different (between the before & after
> > scenario) to introduce an
> > error of any significance. While I don't know
> > conclusively, I strongly
> > suspect that this remains a merely theoretical issue
> > which does not come
> > into play here at all. This, of course, would be a
> > very good thing. :-) I
> > agree that Kurt has done an outstanding job with
> > this project, and believe
> > his conclusion to be valid.
> >
> > I've beat this horse more than enough now. Hope I
> > didn't ruffle any
> > feathers- that certainly was not my intent.
> > Personally, I found this to be a
> > stimulating discussion.
> >
> > Stu
>
>
> __________________________________
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>
>
Message 15
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| Subject: | Re: RE: KitFox N210F "HEAVY" |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Lowell and the List,
--- Lowell Fitt <lcfitt@inreach.com> wrote:
> It would be an interesting addition to Kurt's work
> to see if the effect of VGs were different in
> a lighter loaded wing.
I couldn't really test my plane at much lighter
weights to fit Lowell's question. With only 8.5
gallons of fuel, I can fly a short time at 1200# with
reserves, but it is not a reasonable use of my plane.
I had to go the other way anyway to complete my
testing, so here are some notable results. (BTW, as
of today I am over 40 hrs.)
I loaded up with fuel, sandbags, and water tanks up to
a mighty heavy weight to do these tests. I had 27 gal
of fuel, 210# of sand up front, 110# of water in back,
and 219# of pilot and parachute. (Don't tell the
feds, but I was still 100# short of gross. I'll
interpolate the rest to save my plane.)
Whatever the results, I can say they fit mathematical
predictions very well. I tested 4 cruise settings
including 4 and 6 gph FF. I tested climb rates for Vx
and Vy. I tested stalls too. But no VG's.
I can say that my stall speed change with weight is a
straight line graph at each flap setting. I predict
it should go the other way with lighter weights too -
for my plane. I am a sample size of one and not a
sure outcome for all. I'd certainly help anyone else
who wants to test theirs.
One important result was that the stalls had no left
wing falloff as before. The fall of is very likely
not due to rigging, but MFB. That is, with both seats
occupied, the plane stalled straight ahead. My tandem
seated friends made sure I knew that it was my
fault... Power-on of course it rolled with torque
with my left handed NSI engine, and MFB when I am
alone too. Power-on stalls solo from the right seat
would probably be nice.
I am happy to say that I got some useful data from
these tests. Now I have some very pretty graphs of Vx
and Vy that changed only 3 knots with all that weight
increase. I have stall vs weight graphs for each flap
setting that change 11 knots for my whole weight range
at zero flaps, but less change increasing toward max
flaps. And I have gph vs speed and mpg vs speed
graphs for x-country use. It goes from 12 to 20 mpg,
BTW. Still a little draggy, but the weight increase
didn't effect range much at all. 5% ??? I just
always use the heavy range figures.
And I feel a little better about my tailwheel springs.
I had a measurement of only 1 and 5/16th inches
between the top of my tailwheel mount and the rudder
while heavy, but without me in the plane. I came back
with a bumpy grass runway landing and found no contact
with the rudder. :-) I did thump hard over bumps a
good bit back there too.
I was surprised to find that it was the rudder work
while airborne that was the biggest increase. I had
to press it a good bit harder to keep the ball in the
middle. All that weight wants to wander more sideways
in turbulence? I'm still thinking about it... What
happens when I go to floats?
Tomorrow comes the most dangerous testing of all
-pavement. Then I will sign this plane off as worthy.
Kurt S. S-5/NSI turbo
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| Subject: | Re: VG's and their testing. |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Oh, my fault. Good question too. I water balasted
the plane to a fraction of an inch of centered CG. I
would probably not have had the elevator authority to
stall in some of the tests without the CG brought back
some from solo flight.
The 1 degree fwd sweep bothered me in trying to keep
the VG's at 15 degrees per instructions. I wondered
if a 17 degree angle wouldn't have worked better too.
I've heard some VG providers use more than 15.
Kurt S.
--- Clint Bazzill <clint_bazzill@hotmail.com> wrote:
> I have been reading the results of Kurt's VG testing
> with interest. There are several questions that I
> didn't see answered. One, Kurt is flying a Model V
> with a subaru engine. What is the CG location and
> are the wings swept forward as most heavy Kitfoxes
> are. A forward CG could explain the aircraft not
> being able to spin to the right. Some thought. Clint
__________________________________
Message 17
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| Subject: | Re: VG's and the testing process |
--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220@yahoo.com>
Thanks Jim,
Did you lose much in cruise speed?
I think that it could be my leading edge that is cnx
the improvement, though I am not getting a leading
edge stall, which is usually wicked. Moving them fwd
is a good idea to try. I might try them back up to 6"
too.
Kurt S.
--- jimshumaker <jimshumaker@sbcglobal.net> wrote:
> --> Kitfox-List message posted by: "jimshumaker"
> <jimshumaker@sbcglobal.net>
>
> Hi Kurt
>
> Thanks for filling us in on your VG tests. I have a
> different wing and so
> my setup may not work for you. I did not get a
> reasonable improvement in
> stall until I moved the VG's to 3 inches from the
> leading edge. You might
> want to try that next year. Like you, I would not
> bother keeping them on
> unless there was enough improvement to make enough
> difference to put up with
> their drawbacks.
>
> Jim Shumaker.
>
>
> ----- Original Message -----
> From: "kurt schrader" <smokey_bear_40220@yahoo.com>
> To: <kitfox-list@matronics.com>
> Subject: Re: Kitfox-List: VG's and the testing
> process
>
>
> > --> Kitfox-List message posted by: kurt schrader
> <smokey_bear_40220@yahoo.com>
> >
> > Stu and everyone,
> >
> > I also think this was very stimulating and like
> the
> > scientific mentality to challenge the process and
> > conclusions before accepting them. To me that
> process
> > is bigger and worth more than these single results
> > themselves. I applaud the challengers as those
> with
> > courage enough to promote this necessary
> corrective
> > proceedure.
> >
> > But I would especially like to find a cause and a
> cure
> > for not achieving a slower stall, and wish I had
> that
> > over any pride of authorship. I don't think we
> found
> > one yet. Darn...
> >
> > A few points to make to add to this:
> >
> > A. There was no significant difference in
> indicated
> > stall speeds. If a greater AOA was achieved,
> there
> > should have been some indicated difference, and
> pitot
> > error could then exerate that. I think the angles
> > were always the same for each flap setting no
> matter
> > what VG's were used, +/- a degree.
> >
> > B. One solution to pitot error is to mount the
> pitot
> > tube at a median downward angle so that it is in
> line
> > with the slip stream half way between zero AOA and
> > stall. That would produce an error of very small
> size
> > on either end of the AOA/speed range. I think
> that
> > the error was in fact small at the AOA's I
> achieved.
> > I suspect that only my power-on stall got near 20
> > degrees and the others were around 16.
> >
> > C. But I have the silver bullet - TA DA - an AOA
> > probe, thanks to Elbie and RiteAngle. It points
> into
> > the slipstream and measures AOA directly. For all
> of
> > my stalls tests however, I turned it off so as not
> to
> > distract me or cause "stall anticipation". But
> for
> > later testing I can enable it and have it "report"
> > differences in stall angle, if any. Expect that
> next
> > year though. Too much to do for now. The VG
> testing
> > took 6 days I can't make up. I had hoped it would
> > work in a day or 2.
> >
> > Thanks for all the input. I hope someone finds a
> > better answer.
> >
> > Kurt S. S-5/NSI turbo
> >
> > --- Stu Bryant <s.j.bryant@sbcglobal.net> wrote:
> >
> > > Lowel,
> > > You are very knowledgeable about this, sir.
> Actually
> > > all of you participating in this thread are.
> > >
> > > I have no agenda one way or the other, and
> frankly
> > > do not disagree with any
> > > of the conclusions, either. I wasn't sure
> whether
> > > any potential skewing of
> > > the data by this theoretical dilemma would be
> > > positive or negative. I was
> > > merely concerned that there was potential for a
> > > skewing which might be
> > > difficult to detect. I just thought I saw an
> area
> > > where another
> > > consideration might potentially might be useful.
> > > Evidently with the given
> > > particulars this was not helpful. - OK, I accept
> > > that.
> > >
> > >
> > > You said "...so if Kurt was in a zone of error
> when
> > > clean,
> > > then as the VGs allowed for increased angle of
> > > attack, the error - lower
> > > reading - would be more pronounced."
> > >
> > > Yes I agree completely, just still can't see how
> we
> > > would necessarily
> > > recognize this with the data presented alone-
> > > without an external
> > > validation- IF we slipped into that error range
> > > where the AOA was
> > > sufficiently different (between the before &
> after
> > > scenario) to introduce an
> > > error of any significance. While I don't know
> > > conclusively, I strongly
> > > suspect that this remains a merely theoretical
> issue
> > > which does not come
> > > into play here at all. This, of course, would be
> a
> > > very good thing. :-) I
> > > agree that Kurt has done an outstanding job with
> > > this project, and believe
> > > his conclusion to be valid.
> > >
> > > I've beat this horse more than enough now. Hope
> I
> > > didn't ruffle any
> > > feathers- that certainly was not my intent.
> > > Personally, I found this to be a
> > > stimulating discussion.
> > >
> > > Stu
> >
> >
> > __________________________________
> > Y! Messenger - Communicate in real time. Download
> now.
> >
> >
>
>
>
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