Today's Message Index:
----------------------
0. 12:41 AM - Who is "Matt Dralle" & What Are "The Lists"? [Please Read] (Matt Dralle)
1. 12:45 AM - Re: 701 slats again (secatur)
2. 01:18 AM - Re: 701 slats again (secatur)
3. 03:37 AM - Re: Re: PROP CHOICES (Monty Graves)
4. 03:38 AM - Crack in 601HD firewall stiffner 6F8-2 (Clive Richards)
5. 05:00 AM - 701 slats again (rhartwig11@juno.com)
6. 05:14 AM - Re: Crack in 601HD firewall stiffner 6F8-2 (Jim Hoak)
7. 05:34 AM - Re: 701 slats again (Robert N. Eli)
8. 06:05 AM - Re: 701 slats again (n801bh@netzero.com)
9. 08:36 AM - getting bumped on the digest (john butterfield)
10. 08:41 AM - Re: Crack in 601HD firewall stiffner 6F8-2 (Gig Giacona)
11. 09:23 AM - Re: getting bumped on the digest (Bryan Martin)
12. 12:09 PM - Re: 601XL - Engine out / Glide Experience (Phil Maxson)
13. 12:27 PM - Re: 601XL - Engine out / Glide Experience (Craig Payne)
14. 01:02 PM - Re: 701 slats again (Juan Vega)
15. 01:05 PM - Re: Re: 701 slats again (Juan Vega)
16. 02:44 PM - Enough!!! (Zed Smith)
17. 03:04 PM - Re: Enough!!! (Gary Boothe)
18. 03:40 PM - Re: Enough!!! (John Marzulli)
19. 03:42 PM - Re: Enough!!! (NYTerminat@aol.com)
20. 04:08 PM - Re: Enough!!! (Noel Loveys)
21. 04:15 PM - Re: Enough!!! (Gary Boothe)
22. 05:10 PM - Re: Enough!!! (JOHN STARN)
23. 06:05 PM - Re: 701 slats again (Dennis Wieck)
24. 06:06 PM - Re: Enough!!! (Trevor Page)
25. 06:19 PM - CZAW cowl question (Trevor Page)
26. 07:14 PM - 701 Slats Again (Jim Fosse)
27. 07:31 PM - Re: Enough!!! (ron wehba)
28. 07:59 PM - Re: 701 slats again (secatur)
29. 08:18 PM - Re: Enough!!! (John Bolding)
30. 08:33 PM - Re: Enough!!! (Danny Offill)
31. 09:26 PM - Re: Re: 701 slats again (Ron Culver)
32. 10:44 PM - Re: 701 slats again (secatur)
33. 11:21 PM - Re: 701 slats again (Hans)
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| Subject: | Who is "Matt Dralle" & What Are "The Lists"? [Please Read] |
Dear Listers,
Who is Matt Dralle and what exactly are these Lists? Well, I've been working in
the information technology industry for over 20 years primarily in computer
networking design and implementation. I have also done extensive work in web
development and CGI design during this period.
I started the Matronics Email Lists back in 1990 with about 30 fellow RV builders
from around the world. Since that time, I have added 63 other kinds of aircraft
related Lists to the line up and numerous other List related services such
as the Forums, Wiki, Archives and Search Engine just to name a few.
For flexibility and reliability, I have chosen to run all of my own servers here
locally. Other List-related systems include a 1 Gigabit, fully switched network
infrastructure, a commercial-grade Netscreen firewall, a Barracuda spam filter,
a local T1 Internet router, and a commercial-grade business T1 Internet
connection with full static addressing.
The computer servers found here include a brand new, quad-processor Xeon Linux
server for List web services, a dual-processor Xeon Linux system dedicated to
the email processing List functions, and another P4 Linux system serving as a
remote storage disk farm for the archives, databases, and for an on-line hard
drive-based backup system with 3.2 Terra Bytes of storage, soon to be upgraded
to over 6 Terra Bytes! This entire system is protected by three large, commercial-grade
uninterrupted power supply (UPS) systems that assure the Lists are
available even during a local power outage! Speaking of power, imagine how much
electricity it takes to run all of these systems. One month this Summer,
I had a staggering $1368 bill for electricity alone!
I recently upgraded all of the computer racking infrastructure including new power
feeds and dedicated air conditioning for the room that serves as the Computer
Center for the Matronics Email Lists. This year I added another rack to house
the new MONSTER quad-processor web system that didn't quite fit into the
first rack! Here's a composite photo of the List Computer Center before the addition
of the second rack:
http://www.matronics.com/MattDralle-ListComputerCenter.jpg
As you can see, I take running these Lists very seriously and I am dedicated to
providing an always-on, 24x7x365 experience for each and every Lister.
But building and running this system isn't cheap. As I've stated before, I don't
support any of these systems with commercial advertising on the Lists. It
is supported 100% through List member Contributions! That means you... and you...
and YOU!
To that end, I hold a List Fund Raiser each November and ask that members make
a small Contribution to support the continued operation and upgrade of this ever-expanding
system. Its solely YOUR Contributions that keeps it running!
Please make a Contribution today to support these Lists!
http://www.matronics.com/contribution
Or, by dropping a personal check in the mail to:
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(Please include your email address on the check!)
Thank you!
Matt Dralle
Matronics Email List Administrator
Message 1
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| Subject: | Re: 701 slats again |
I find it extremely interesting that there are so many comments regarding VGs /
vs Slats on the 701, and yet very few respondents seem to have read or studied
much of the almost 50 years of accumulated aircraft experience regarding VGs.
If you go hunting, you will find literally hundreds of hours of actual flight comparisons,
including specs of flight testing and results. The result on the 701
(with VGs INSTEAD of slats!) appears to be a slight improvement in low speed
handling together with a slight improvement in top/cruise of about 5kn. One
builder/pilot actually documented 140 hr of testing before finally deciding to
remove the slat mountings altogether !
Why would Savannah (yeah dirty word..sorry) actually go to the trouble of offering
the VG slatless (exactly same wing/airfoil) option on it's current price list
if it didn't offer some value?
Is this where "Do Not Archive" goes?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=77503#77503
Message 2
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| Subject: | Re: 701 slats again |
More interesting reading
The vast reduction in drag allows all these aircraft to fly considerably faster
for the same power, climb better, glide better, and with the benefit of Vortex
Generators, lift-off and touch-down just as short as with slats, but with more
control.
In summary for my Savannah:
Fast cruise @ 5200 rpm has gone from 79 kt to 85 kt. = + 6 kts
Top speed has gone from 94 kts to 103 kts! = + 9 kts.
Fuel burn @ 75 kts has gone from 17 L/hr to 13 L/hr. = 23.5% less!
Best climb rate @ 55 kts is 100 fpm higher.
Best glide @ 40-45 kts is 100 fpm better.
Stalls (idle power, no flap):
With slats no real stall, just a stable high-descent mush @ less than 30 kts.
Without slats, no VGs* a distinct stall and roll to the left @ 34 kts.
Without slats and with VGs no stall, just a stable mush @ less than 30 kts.
*VGs = Vortex Generators, more about them elsewhere.
L/hr x 0.26 = US Gal/hr.
Kts x 1.15 = mph.
This testing was done in a Savannah aircraft, a kitplane from I.C.P. in Italy, www.icp.it/avio.htm or http://www.skykits.com/ . Its pretty much a clone of a Zenair CH701, same wing profile but a longer wing, and a different tail section. Powered by a 100hp 912ULS, 4-blade Brolga prop pitched for climb (16 blocks), carrying pilot (73kg) and 30 litres fuel.
ore interesting reading from www.stolspeed.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=77566#77566
Message 3
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| Subject: | Re: RE: PROP CHOICES |
Don't forget about Culver props.
www.culverprops.com
Message 4
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| Subject: | Crack in 601HD firewall stiffner 6F8-2 |
Hi list we have found a crack in the firewall stiffner near the port
engine mount and have had to replace the stiffner
We beleave this may be because we are using a Continental 0-200 & a
header tank so are on a fairley forward C of G. Have any of you with
this combination had any problems ?
We have difficulty in Just lowering the nose on landing, it
tends to want to drop when you remove the power. It is possably caused
because to much we trimmed off the stiffner to fit the original faulty
engine mount.
We found this when changing the nose wheel bungey which was fraid
at the bottom tube and started to shed rubber.
We have done a lot of tuch & goes try to perfect our landings
Clive Richards
GCBDG 52 Hrs Estimated 250 T&G / Landings
Message 5
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This discussion contains a lot of speculation on what would happen if you
removed the slats or covered the slot between slats and wings, etc. Some
of it is not very well thought out as to what happens to the CG range. I
would suggest trying to learn from those who have removed the slats and
are flying their 701's in that configuration (and I suppose the
experience with modified Savannahs should also be considered.) I would
hope that anyone making this modification would use the data from those
who have been successful and would then proceed with extreme caution. I
understand that the CG range on the 701 is approximately 30-39 % of the
airfoil measured from the front of the slat--I have not checked that out
myself. Unslatted wings are usually approximately 20 to 28% (Forgive me
if these numbers are off of few % + or -.) What is the CG range of the
701 airfoil if you measure from the leading edge of the wing instead of
the slat? Is a slat aerodynamically part of the airfoil when calculating
CG range? I don't know, but you can bet I am going to find out. Also
keep in mind the effect of removing the weight of the slats even though
they are light and have a small moment arm. Think it out. Research it.
Learn from others who've "dunit." Proceed with caution.
Rich Hartwig, 701 kit
Waunakee, WI
rhartwig11@juno.com
Message 6
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| Subject: | Re: Crack in 601HD firewall stiffner 6F8-2 |
Clive,
If I remember correctly, Art Mitchell had this problem with early 601HDs
used for training. ( Lots of landings). I think he was using Rotax
engines though. The fix was a "L" stiffner riveted on to each end of
6F8-2 along the diaginal edges. I heard of this and added the stiffners
before ever flying my HD. (1996) I now have 745 landings and 536 hours.
Even with the Rotax 912UL I find that I need to keep much UP elevator
just at touch-down to keep the nose wheel from dropping down fairly
hard. I have found that the slower you get the airplane just before the
mains touch, the less tendency to bang the nose down. In other words,
slow it down on landing. I keep reminding myself and now make very
consistant and SOFT landings.
Jim Hoak 912UL - 536 hrs - 745 landings
----- Original Message -----
From: Clive Richards
To: zenith-list@matronics.com
Sent: Tuesday, November 28, 2006 6:26 AM
Subject: [Norton AntiSpam] Zenith-List: Crack in 601HD firewall
stiffner 6F8-2
Hi list we have found a crack in the firewall stiffner near the port
engine mount and have had to replace the stiffner
We beleave this may be because we are using a Continental 0-200 & a
header tank so are on a fairley forward C of G. Have any of you with
this combination had any problems ?
We have difficulty in Just lowering the nose on landing, it
tends to want to drop when you remove the power. It is possably caused
because to much we trimmed off the stiffner to fit the original faulty
engine mount.
We found this when changing the nose wheel bungey which was fraid
at the bottom tube and started to shed rubber.
We have done a lot of tuch & goes try to perfect our landings
Clive Richards
GCBDG 52 Hrs Estimated 250 T&G / Landings
Message 7
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| Subject: | Re: 701 slats again |
Rich,
I completely agree with your recommendations. Just removing the 701 slat,
with no modifications, produces a "snub-nosed" airfoil, that is unlike any
standard airfoil, and would seem to create all sorts of potentially
dangerous issues. If the slot is covered, and the original NACA airfoil is
recovered, then there will be CG range issues that should be carefully
researched before risking the change. I think the information to answer the
latter questions are out there somewhere. I know that extensive research
has been conducted in the past comparing airfoils with and without slats.
Bob Eli
N701K
----- Original Message -----
From: <rhartwig11@juno.com>
Sent: Tuesday, November 28, 2006 7:56 AM
Subject: Zenith-List: 701 slats again
>
> This discussion contains a lot of speculation on what would happen if you
> removed the slats or covered the slot between slats and wings, etc. Some
> of it is not very well thought out as to what happens to the CG range. I
> would suggest trying to learn from those who have removed the slats and
> are flying their 701's in that configuration (and I suppose the
> experience with modified Savannahs should also be considered.) I would
> hope that anyone making this modification would use the data from those
> who have been successful and would then proceed with extreme caution. I
> understand that the CG range on the 701 is approximately 30-39 % of the
> airfoil measured from the front of the slat--I have not checked that out
> myself. Unslatted wings are usually approximately 20 to 28% (Forgive me
> if these numbers are off of few % + or -.) What is the CG range of the
> 701 airfoil if you measure from the leading edge of the wing instead of
> the slat? Is a slat aerodynamically part of the airfoil when calculating
> CG range? I don't know, but you can bet I am going to find out. Also
> keep in mind the effect of removing the weight of the slats even though
> they are light and have a small moment arm. Think it out. Research it.
> Learn from others who've "dunit." Proceed with caution.
> Rich Hartwig, 701 kit
> Waunakee, WI
> rhartwig11@juno.com
>
>
>
Message 8
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| Subject: | Re: 701 slats again |
Bob, I agree with you 100% on your clarification. In fact several of us
801 guys discussed doing just this to see if the speed increased. We eve
n researched the type of tape needed to do this and came up with some he
licopter stuff that was 12" wide. Maybe one day I will experiment.!!!
do not archive
Ben Haas
N801BH
www.haaspowerair.com
-- "Robert N. Eli" <robert.eli@adelphia.net> wrote:
I may have caused some misunderstanding by my use of the word "remove".
I am not advocating removal of the 701 slat. The point I was making is
that Chris Heintz designed the 701 slat by simply starting with the NACA
640-18 airfoil shape and then adding the opening (the gap between the s
lat and the rest of the wing) through which the air flows from the lower
surface to the upper surface. He sketched this very process for me by
drawing the original airfoil first, and then adding the air slot afterwa
rds, to divide the nose of the airfoil from the remaining aft portion. Y
ou can in effect "remove" the slat by covering the openings on top and b
ottom. Doing this "removes" the slat, returning the wing airfoil to its
original NACA 640-18 shape. Covering the slat openings so that the origi
nal NACA 640-18 shape results should not cause a major change in the cen
ter of pressure at normal flight angles of attack (and hence stability).
Of course, the lift will be significantly reduced at high angles of att
ack. Bob EliN701K ----- Original Message ----- From: n801bh@netzero.co
m To: zenith-list@matronics.com Sent: Monday, November 27, 2006 8:09 PMS
ubject: Re: Zenith-List: 701 slats again
I don't know about the 701 but,, the 801's slat leading edge profile is
nothing like the wings leading edge profile. I will look very close at a
701 when I see one to see if it's like the bigger brothers. I would NEV
ER remove my 801's slats and fly with just the wing alone. but heck, tha
ts just me... YMMV.
do not archive
Ben Haas
N801BH
www.haaspowerair.com
-- "Robert N. Eli" <robert.eli@adelphia.net> wrote:
net>
Carl,
I talked to Chris Heintz at Air Venture several years ago about the 701
airfoil, and the aerodynamic design of the slats. The airfoil is an old
standard airfoil (it is a NACA 640-18) with just a slot added. In othe
r
words, if you simply remove the slot and leave the fixed slat in its des
ign
postion to define the nose of the airfoil, then you have standard NACA
640-18 airfoil. If one wants to remove the slat from the airfoil design,
the
original airfoil can be recovered by simply covering the slots with shee
t
metal that matches the airfoil contour.
Bob Eli
----- Original Message -----
From: "Carl Bertrand" <cgbrt@mondenet.com>
Sent: Monday, November 27, 2006 8:18 AM
Subject: Fw: Zenith-List: 701 slats again
>
>
> From: "Carl Bertrand" <cgbrt@mondenet.com>
> To: <zenith-list@matronics.com>
>
> Subject: Re: Zenith-List: 701 no slats again
>
> Hi Joe
> Have followed this thread with interest.
> I've experimented with the 701's wing design but not with vgs. I opted
for
> air pressure operated slats and a thinner airfoil.
> For more info on the results see my presentation at: eaa245.dhs.org/
> I never considered flying the 701 without slat but I'm not surprised t
hat
> it could be a hand full. My take is that the Cof G and the centre of
> pressure would move back, the Cp more so causing a nose heavy pitch mo
ment
> at all speeds and angles of attack. I would expect all stall speeds to
> increase with the clean wing and top speed to probably remain the same
or
> decrease because of the blunt leading edge.
> Adding vgs should delay the stall but should also increase drag?
> Very interested in the results anyone gets if you try the no slat
> configuration.
>
> Carl 701/912/amphibs
>
>
>=======================sp
; -- Please Support Your Lists Thinbsp; (And Get Some AWESOME FREE&nb
nbsp;Annual List Fund Raiser. Click on
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=================
<html><P>Bob, I agree with you 100% on your clarification. In fact sever
al of us 801 guys discussed doing just this to see if the speed increase
d. We even researched the type of tape needed to do this and came up wit
h some helicopter stuff that was 12" wide. Maybe one day I will experime
nt.!!!</P>
<P>do not archive<BR><BR><BR>Ben Haas<BR>N801BH<BR>www.haaspowerair
.com<BR><BR>-- "Robert N. Eli" <robert.eli@adelph
ia.net> wrote:<BR></P>
<DIV><FONT face=Arial size=2>I may have caused some misunderstanding
by my use of the word "remove". I am not advocating removal of th
e 701 slat. The point I was making is that Chris Heintz designed the 701
slat by simply starting with the NACA 640-18 airfoil shape and then add
ing the opening (the gap between the slat and the rest of the wing)
through which the air flows from the lower surface to the upper su
rface. He sketched this very process for me by drawing the origina
l airfoil first, and then adding the air slot afterwards, to divide the
nose of the airfoil from the remaining aft portion. You can in effect "r
emove" the slat by covering the openings on top and bottom. Doing t
his "removes" the slat, returning the wing airfoil to its original NACA
640-18 shape. Covering the slat openings so that the original NACA
640-18 shape results should not cause a major change in the ce
nter of pressure at normal flight angles of attack (and hence stability)
. Of course, the lift will be significantly reduced at high angles of&nb
sp;attack.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Bob Eli</FONT></DIV>
<DIV><FONT face=Arial size=2>N701K </FONT></DIV>
<BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MA
RGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">
<B>From:</B> <A title=n801bh@netzero.com href="mailto:n801bh@netzero
.com">n801bh@netzero.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=zenith-list@matron
ics.com href="mailto:zenith-list@matronics.com">zenith-list@matronics.
com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, November 27, 2006 8
:09 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Zenith-List: 701 sla
ts again</DIV>
<DIV><BR></DIV>
<P>I don't know about the 701 but,, the 801's slat leading edge profile
is nothing like the wings leading edge profile. I will look very close a
t a 701 when I see one to see if it's like the bigger brothers. I w
ould NEVER remove my 801's slats and fly with just the wing alone. but h
eck, thats just me... YMMV.</P>
<P>do not archive<BR><BR><BR>Ben Haas<BR>N801BH<BR>www.haaspowerair
.com<BR><BR>-- "Robert N. Eli" <robert.eli@adelph
ia.net> wrote:<BR>--> Zenith-List message post
ed by: "Robert N. Eli" <robert.eli@adelphia.
net><BR><BR>Carl,<BR><BR>I talked to Chris Heintz
at Air Venture several years ago abo
ut the 701 <BR>airfoil, and the aerodynami
c design of the slats. The airfoil&n
bsp;is an old <BR>standard airfoil (it is&
nbsp;a NACA 640-18) with just a slot
added. In other <BR>words, if you&n
bsp;simply remove the slot and leave the&n
bsp;fixed slat in its design <BR>postion t
o define the nose of the airfoil, the
n you have standard NACA <BR>640-18 airfoi
l. If one wants to remove the slat&nb
sp;from the airfoil design, the <BR>original&nb
sp;airfoil can be recovered by simply cove
ring the slots with sheet <BR>metal that&n
bsp;matches the airfoil contour.<BR><BR>Bob Eli<BR><
BR>----- Original Message ----- <BR>From: "Carl
Bertrand" <cgbrt@mondenet.com><BR>To: <zenith-l
ist@matronics.com><BR>Sent: Monday, November 27,
2006 8:18 AM<BR>Subject: Fw: Zenith-List: 701&n
bsp;slats again<BR><BR><BR>> --> Zenith-List m
essage posted by: "Carl Bertrand" <cgbrt@mon
denet.com><BR>><BR>><BR>><BR>><BR>><BR>><BR>>&nb
sp;From: "Carl Bertrand" <cgbrt@mondenet.com><BR>&g
t; To: <zenith-list@matronics.com><BR>><BR>>
Subject: Re: Zenith-List: 701 no slats aga
in<BR>><BR>> Hi Joe<BR>> Have followed 
;this thread with interest.<BR>> I've experi
mented with the 701's wing design but 
;not with vgs. I opted for<BR>> air&nbs
p;pressure operated slats and a thinner ai
rfoil.<BR>> For more info on the result
s see my presentation at: eaa245.dhs.org/
<BR>> I never considered flying the 701
without slat but I'm not surprised t
hat<BR>> it could be a hand full.
My take is that the Cof G and th
e centre of<BR>> pressure would move ba
ck, the Cp more so causing a nose&nbs
p;heavy pitch moment<BR>> at all speeds 
;and angles of attack. I would expect 
;all stall speeds to<BR>> increase with 
;the clean wing and top speed to prob
ably remain the same or<BR>> decrease b
ecause of the blunt leading edge.<BR>>
Adding vgs should delay the stall but 
;should also increase drag?<BR>> Very intere
sted in the results anyone gets if yo
u try the no slat<BR>> configuration.<BR>>
;<BR>> Carl 701/912/amphibs<BR>><BR>><BR>><BR>>
=======================sp;
-- Please Support Your Lists Thinbs
p; (And Get Some AWESOME FREE&n
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OP;&NBSP;&NBSP;*&NBSP;THE&NBSP;BUILDER'S&NBSP;BOOKSTORE&NBSP;WWW.BUILDER
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NBSP;SEARCH&NBSP;&&NBSP;DOWNLOAD,&NBSP;7-DAY&NBSP;BROWSE,&NBSP;CHA=
==================<BR></P><PRE><B><F
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Message 9
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| Subject: | getting bumped on the digest |
Hi list
for the past several months, i have been getting
bumped off the digest about once or twice a week.
when it happens now, i usually find it in my bulk mail
folder. i move it and it works for awhile then gets
bumped. not much effort to move according to the value
of the list. next time it happens to you, check your
bulk mail folder
john butterfield
601XL, corvair
torrance, ca
Message 10
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| Subject: | Re: Crack in 601HD firewall stiffner 6F8-2 |
Any way we can get a photo of the crack? I'd like to make sure I know exactly where
it is developing.
[quote="s.c.richards(at)homecall."]Hi list we have found a crack in the firewall
stiffner near the port engine mount and have had to replace the stiffner
We beleave this may be because we are using a Continental 0-200 & a header tank
so are on a fairley forward C of G. Have any of you with this combination
had any problems ?
We have difficulty in Just lowering the nose on landing, it tends to
want to drop when you remove the power. It is possably caused because to much
we trimmed off the stiffner to fit the original faulty engine mount.
We found this when changing the nose wheel bungey which was fraid at the
bottom tube and started to shed rubber.
We have done a lot of tuch & goes try to perfect our landings
Clive Richards
GCBDG 52 Hrs Estimated 250 T&G / Landings
> [b]
--------
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=77620#77620
Message 11
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| Subject: | Re: getting bumped on the digest |
Create a rule to handle the mail received from the list so that the
bulk mail filter will ignore it. That should solve the problem
permanently.
On Nov 28, 2006, at 11:35 AM, john butterfield wrote:
> <jdbutterfield@yahoo.com>
>
> Hi list
> for the past several months, i have been getting
> bumped off the digest about once or twice a week.
> when it happens now, i usually find it in my bulk mail
> folder. i move it and it works for awhile then gets
> bumped. not much effort to move according to the value
> of the list. next time it happens to you, check your
> bulk mail folder
> john butterfield
> 601XL, corvair
> torrance, ca
--
Bryan Martin
N61BM, CH 601 XL,
RAM Subaru, Stratus redrive.
do not archive.
Message 12
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| Subject: | 601XL - Engine out / Glide Experience |
Here is some very practical information about how I make landings. So far
I've got about 120 hours on my plane, and I don't know how many landings.
I would say maybe 80 - 100.
When I fly a standard landing pattern (i.e. same as a Cessna 152/172) I use
about 75% power on the downwind leg. I leave that amount of power in unti
l I get to the corner, that is, until I turn base. At that point I'm still
1000 feet AGL, and I pull the power back to almost idle. I glide in from
there with minor changes to power. If I'm low, I add power, if I'm high I
use more flaps, or even add a side slip.
So to answer your original question, the glide performance isn't as good as
a 172, but it's not that different. Best glide speed is about 85 mph in m
y plane.Phil Maxson601XL/CorvairNorthwest New Jersey
h-List: 601XL - Engine out / Glide ExperienceTo: zenith-list-digest@matroni
cs.com
Hello All,
I am planning to build a 601XL in the near future and have been reading the
recent threads about the unfortunate loss of a 601XL and pilot.
I don't know what happened and don't want to speculate about what happened,
etc. I would like to know if anyone has experience with simulated engine o
ut landings and would share those experiences with the group? I would also
appreciate any experiences with how the 601XL glides during simulated engin
e out practice and any comparisons to other aircraft, i.e. Cessna 172, etc.
Thanks in advance,
Steven
_________________________________________________________________
Message 13
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| Subject: | 601XL - Engine out / Glide Experience |
Phil - how do you set the flaps during the various phases of landing?
-- Craig
Message 14
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| Subject: | Re: 701 slats again |
If you remove the slat or cover it it won't just reduce the speed at high angles,
at any angle over 15degrees. THE PLANE WILL STALL. That is what the slat does
is force the air over the wing at angles over 15 degrees. PLane will still
work great with the high cord wing if you cover the slat gap. but no extreme
pull up angles any more.
Juan
-----Original Message-----
>From: "n801bh@netzero.com" <n801bh@netzero.com>
>Sent: Nov 28, 2006 9:02 AM
>To: zenith-list@matronics.com
>Subject: Re: Zenith-List: 701 slats again
>
>Bob, I agree with you 100% on your clarification. In fact several of us 801 guys
discussed doing just this to see if the speed increased. We even researched
the type of tape needed to do this and came up with some helicopter stuff that
was 12" wide. Maybe one day I will experiment.!!!
>do not archive
>
>
>Ben Haas
>N801BH
>www.haaspowerair.com
>
>-- "Robert N. Eli" <robert.eli@adelphia.net> wrote:
>
>I may have caused some misunderstanding by my use of the word "remove". I am
not advocating removal of the 701 slat. The point I was making is that Chris Heintz
designed the 701 slat by simply starting with the NACA 640-18 airfoil shape
and then adding the opening (the gap between the slat and the rest of the
wing) through which the air flows from the lower surface to the upper surface.
He sketched this very process for me by drawing the original airfoil first,
and then adding the air slot afterwards, to divide the nose of the airfoil from
the remaining aft portion. You can in effect "remove" the slat by covering the
openings on top and bottom. Doing this "removes" the slat, returning the wing
airfoil to its original NACA 640-18 shape. Covering the slat openings so that
the original NACA 640-18 shape results should not cause a major change in the
center of pressure at normal flight angles of attack (and hence stability).
Of course, the lift will be significantly reduced at
high angles of attack. Bob EliN701K ----- Original Message ----- From: n801bh@netzero.com
To: zenith-list@matronics.com Sent: Monday, November 27, 2006 8:09
PMSubject: Re: Zenith-List: 701 slats again
>I don't know about the 701 but,, the 801's slat leading edge profile is nothing
like the wings leading edge profile. I will look very close at a 701 when I
see one to see if it's like the bigger brothers. I would NEVER remove my 801's
slats and fly with just the wing alone. but heck, thats just me... YMMV.
>do not archive
>
>
>Ben Haas
>N801BH
>www.haaspowerair.com
>
>-- "Robert N. Eli" <robert.eli@adelphia.net> wrote:
>
>Carl,
>
>I talked to Chris Heintz at Air Venture several years ago about the 701
>airfoil, and the aerodynamic design of the slats. The airfoil is an old
>standard airfoil (it is a NACA 640-18) with just a slot added. In other
>words, if you simply remove the slot and leave the fixed slat in its design
>postion to define the nose of the airfoil, then you have standard NACA
>640-18 airfoil. If one wants to remove the slat from the airfoil design, the
>original airfoil can be recovered by simply covering the slots with sheet
>metal that matches the airfoil contour.
>
>Bob Eli
>
>----- Original Message -----
>From: "Carl Bertrand" <cgbrt@mondenet.com>
>To: <zenith-list@matronics.com>
>Sent: Monday, November 27, 2006 8:18 AM
>Subject: Fw: Zenith-List: 701 slats again
>
>
>>
>>
>>
>>
>>
>>
>> From: "Carl Bertrand" <cgbrt@mondenet.com>
>> To: <zenith-list@matronics.com>
>>
>> Subject: Re: Zenith-List: 701 no slats again
>>
>> Hi Joe
>> Have followed this thread with interest.
>> I've experimented with the 701's wing design but not with vgs. I opted for
>> air pressure operated slats and a thinner airfoil.
>> For more info on the results see my presentation at: eaa245.dhs.org/
>> I never considered flying the 701 without slat but I'm not surprised that
>> it could be a hand full. My take is that the Cof G and the centre of
>> pressure would move back, the Cp more so causing a nose heavy pitch moment
>> at all speeds and angles of attack. I would expect all stall speeds to
>> increase with the clean wing and top speed to probably remain the same or
>> decrease because of the blunt leading edge.
>> Adding vgs should delay the stall but should also increase drag?
>> Very interested in the results anyone gets if you try the no slat
>> configuration.
>>
>> Carl 701/912/amphibs
>>
>>
>>
>>=======================sp; -- Please Support Your Lists Thinbsp; (And Get
Some AWESOME FREE&nbnbsp;Annual List Fund Raiser. Click on
>href="http://www.aeroelectric.com">www.aeroelectric.comhref="http://www.buildersbooks.com">www.buildersbooks.comhref="http://www.kitlog.com">www.kitlog.comhref="http://www.homebuilthelp.com">www.homebuilthelp.comhref="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?Zenith-List">http://www.=========================================================================================
Message 15
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| Subject: | Re: 701 slats again |
you will not gain as mouch speed if you do not elliminate the negative lift foil
horizontal stab. That is what the savana did. hence the higher speed.
-----Original Message-----
>From: secatur <appraise1@bigpond.com>
>Sent: Nov 28, 2006 4:18 AM
>To: zenith-list@matronics.com
>Subject: Zenith-List: Re: 701 slats again
>
>
>More interesting reading
>
>
>The vast reduction in drag allows all these aircraft to fly considerably faster
for the same power, climb better, glide better, and with the benefit of Vortex
Generators, lift-off and touch-down just as short as with slats, but with more
control.
>
>In summary for my Savannah:
>
>Fast cruise @ 5200 rpm has gone from 79 kt to 85 kt. = + 6 kts
>Top speed has gone from 94 kts to 103 kts! = + 9 kts.
>Fuel burn @ 75 kts has gone from 17 L/hr to 13 L/hr. = 23.5% less!
>Best climb rate @ 55 kts is 100 fpm higher.
>Best glide @ 40-45 kts is 100 fpm better.
>
>Stalls (idle power, no flap):
>With slats no real stall, just a stable high-descent mush @ less than 30 kts.
>Without slats, no VGs* a distinct stall and roll to the left @ 34 kts.
>Without slats and with VGs no stall, just a stable mush @ less than 30 kts.
>
>*VGs = Vortex Generators, more about them elsewhere.
>L/hr x 0.26 = US Gal/hr.
>Kts x 1.15 = mph.
>
>This testing was done in a Savannah aircraft, a kitplane from I.C.P. in Italy, www.icp.it/avio.htm or http://www.skykits.com/ . Its pretty much a clone of a Zenair CH701, same wing profile but a longer wing, and a different tail section. Powered by a 100hp 912ULS, 4-blade Brolga prop pitched for climb (16 blocks), carrying pilot (73kg) and 30 litres fuel.
>ore interesting reading from www.stolspeed.com
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=77566#77566
>
>
Message 16
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Will you guys in the northern latitudes just cut it out??
North Texas has enjoyed mild temps in the mid 70's for two or three months.....now
we are told that somebody north of Oklahoma has left a gate open.
It is 73 F as I type this plea for sanity.....close those gates, fellows! The
prediction is for 25 F Friday morning, and the "S-word" has been mentioned.
We may have to resort to wearing sleeves as we pull rivets and use the dreaded
Green ScotchBrite pads.
Have mercy......
Regards to all who are snowbound,
Zed
do not archive!!!
Message 17
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Zed,
Think of the boom to your economy. Walmart could start selling heaters (no
not guns. You plug them into the wall and they get the room warm!)
Gary Boothe
Cool, CA
601 HDSTD, WW Conversion 90% done,
Tail done, wings done, working on c-section
Do not Archive
-----Original Message-----
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com] On Behalf Of Zed Smith
Sent: Tuesday, November 28, 2006 2:22 PM
Subject: Zenith-List: Enough!!!
Will you guys in the northern latitudes just cut it out??
North Texas has enjoyed mild temps in the mid 70's for two or three
months.....now we are told that somebody north of Oklahoma has left a gate
open.
It is 73 F as I type this plea for sanity.....close those gates, fellows!
The prediction is for 25 F Friday morning, and the "S-word" has been
mentioned.
We may have to resort to wearing sleeves as we pull rivets and use the
dreaded Green ScotchBrite pads.
Have mercy......
Regards to all who are snowbound,
Zed
do not archive!!!
Message 18
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What ever they did in OK, it hit us here in Seattle. We haven't seen
temperatures this low in years! We got more snow in the last two days then
in the previous three years combined!
On 11/28/06, Zed Smith <zsmith3rd@earthlink.net> wrote:
>
>
> Will you guys in the northern latitudes just cut it out??
> North Texas has enjoyed mild temps in the mid 70's for two or three
> months.....now we are told that somebody north of Oklahoma has left a gate
> open.
> It is 73 F as I type this plea for sanity.....close those gates,
> fellows! The prediction is for 25 F Friday morning, and the "S-word" has
> been mentioned.
> We may have to resort to wearing sleeves as we pull rivets and use the
> dreaded Green ScotchBrite pads.
> Have mercy......
>
> Regards to all who are snowbound,
>
> Zed
>
> do not archive!!!
>
>
--
John Marzulli
http://701Builder.blogspot.com/
"Flying a plane is no different than riding a bicycle... it's just a lot
harder to put baseball cards in the spokes.
Message 19
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By all means leave the gate open!!!! 63 degrees today, sunny and smooth
flying.
Upstate New York
N701ZX CH701/912S
In a message dated 11/28/2006 5:45:59 P.M. Eastern Standard Time,
zsmith3rd@earthlink.net writes:
--> Zenith-List message posted by: Zed Smith <zsmith3rd@earthlink.net>
Will you guys in the northern latitudes just cut it out??
North Texas has enjoyed mild temps in the mid 70's for two or three
months.....now we are told that somebody north of Oklahoma has left a gate open.
It is 73 F as I type this plea for sanity.....close those gates, fellows!
The prediction is for 25 F Friday morning, and the "S-word" has been mentioned.
We may have to resort to wearing sleeves as we pull rivets and use the
dreaded Green ScotchBrite pads.
Have mercy......
Regards to all who are snowbound,
Zed
do not archive!!!
Message 20
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Never mind the heaters.. Just think of the extra sales of studded tires!!
Not to mention road salt! Or S$%^@# blowers ;-) Oh yes and Santa will
have so much an easier time.
Noel
> -----Original Message-----
> From: owner-zenith-list-server@matronics.com
> [mailto:owner-zenith-list-server@matronics.com] On Behalf Of
> Gary Boothe
> Sent: Tuesday, November 28, 2006 7:34 PM
> To: zenith-list@matronics.com
> Subject: RE: Zenith-List: Enough!!!
>
>
>
> Zed,
>
> Think of the boom to your economy. Walmart could start
> selling heaters (no
> not guns. You plug them into the wall and they get the room warm!)
>
> Gary Boothe
> Cool, CA
> 601 HDSTD, WW Conversion 90% done,
> Tail done, wings done, working on c-section
> Do not Archive
>
> -----Original Message-----
> From: owner-zenith-list-server@matronics.com
> [mailto:owner-zenith-list-server@matronics.com] On Behalf Of Zed Smith
> Sent: Tuesday, November 28, 2006 2:22 PM
> To: zenith-list@matronics.com
> Subject: Zenith-List: Enough!!!
>
>
> Will you guys in the northern latitudes just cut it out??
> North Texas has enjoyed mild temps in the mid 70's for two or three
> months.....now we are told that somebody north of Oklahoma
> has left a gate
> open.
> It is 73 F as I type this plea for sanity.....close those
> gates, fellows!
> The prediction is for 25 F Friday morning, and the "S-word" has been
> mentioned.
> We may have to resort to wearing sleeves as we pull rivets and use the
> dreaded Green ScotchBrite pads.
> Have mercy......
>
> Regards to all who are snowbound,
>
> Zed
>
> do not archive!!!
>
>
>
>
>
>
>
>
>
>
>
Message 21
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Yeah, global warming..oops, sorry, no polytiks.I withdraw my comment..
_____
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com] On Behalf Of John Marzulli
Sent: Tuesday, November 28, 2006 3:39 PM
Subject: Re: Zenith-List: Enough!!!
What ever they did in OK, it hit us here in Seattle. We haven't seen
temperatures this low in years! We got more snow in the last two days then
in the previous three years combined!
On 11/28/06, Zed Smith <zsmith3rd@earthlink.net> wrote:
Will you guys in the northern latitudes just cut it out??
North Texas has enjoyed mild temps in the mid 70's for two or three
months.....now we are told that somebody north of Oklahoma has left a gate
open.
It is 73 F as I type this plea for sanity.....close those gates, fellows!
The prediction is for 25 F Friday morning, and the "S-word" has been
mentioned.
We may have to resort to wearing sleeves as we pull rivets and use the
dreaded Green ScotchBrite pads.
--
John Marzulli
http://701Builder.blogspot.com/
"Flying a plane is no different than riding a bicycle... it's just a lot
harder to put baseball cards in the spokes.
Message 22
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Snow...??? OH, that white cold stuff we got a coupla inches of in three
of the past dozen years.
KABONG. Apple Valley, Calif. Do Not Archive
----- Original Message -----
From: John Marzulli
To: zenith-list@matronics.com
Sent: Tuesday, November 28, 2006 3:38 PM
Subject: Re: Zenith-List: Enough!!!
What ever they did in OK, it hit us here in Seattle. We haven't seen
temperatures this low in years! We got more snow in the last two days
then in the previous three years combined!
On 11/28/06, Zed Smith <zsmith3rd@earthlink.net> wrote:
<zsmith3rd@earthlink.net>
Will you guys in the northern latitudes just cut it out??
North Texas has enjoyed mild temps in the mid 70's for two or three
months.....now we are told that somebody north of Oklahoma has left a
gate open.
It is 73 F as I type this plea for sanity.....close those gates,
fellows! The prediction is for 25 F Friday morning, and the "S-word"
has been mentioned.
We may have to resort to wearing sleeves as we pull rivets and use
the dreaded Green ScotchBrite pads.
--
John Marzulli
http://701Builder.blogspot.com/
"Flying a plane is no different than riding a bicycle... it's just a
lot harder to put baseball cards in the spokes.
Message 23
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| Subject: | Re: 701 slats again |
He said remove the SLOT not the SLAT
> Carl,
>
> I talked to Chris Heintz at Air Venture several years ago about the 701
> airfoil, and the aerodynamic design of the slats. The airfoil is an old
> standard airfoil (it is a NACA 640-18) with just a slot added. In other
> words, if you simply remove the slot and leave the fixed slat in its design
> postion to define the nose of the airfoil, then you have standard NACA
> 640-18 airfoil. If one wants to remove the slat from the airfoil design, the
> original airfoil can be recovered by simply covering the slots with sheet
> metal that matches the airfoil contour.
>
> Bob Eli
Message 24
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Positively balmy here in Southern Ontario for the past week. It's
gonna drop like a rock though come Saturday...
Buffalo will surely get hit with 5 feet of snow ;)
Trev Page
C-IDUS 601HD R912
On Nov 28, 2006, at 5:21 PM, Zed Smith wrote:
>
> Will you guys in the northern latitudes just cut it out??
> North Texas has enjoyed mild temps in the mid 70's for two or three
> months.....now we are told that somebody north of Oklahoma has left
> a gate open.
> It is 73 F as I type this plea for sanity.....close those gates,
> fellows! The prediction is for 25 F Friday morning, and the "S-
> word" has been mentioned.
> We may have to resort to wearing sleeves as we pull rivets and use
> the dreaded Green ScotchBrite pads.
> Have mercy......
>
> Regards to all who are snowbound,
>
> Zed
>
> do not archive!!!
>
>
Message 25
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| Subject: | CZAW cowl question |
Message 26
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For an interesting and informative commentary on 701 and Savannah slats,
or the lack thereof, go to: www.stolspeed.com.
Jim Fosse
Message 27
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hi zed, ron here in rotan, north west of abilene, we are gittin' out a da
way of it , going to canton for the next few days. wind might not even be
blowing there,, stay warm
----- Original Message -----
From: "Zed Smith" <zsmith3rd@earthlink.net>
Sent: Tuesday, November 28, 2006 4:21 PM
Subject: Zenith-List: Enough!!!
>
> Will you guys in the northern latitudes just cut it out??
> North Texas has enjoyed mild temps in the mid 70's for two or three
> months.....now we are told that somebody north of Oklahoma has left a gate
> open.
> It is 73 F as I type this plea for sanity.....close those gates, fellows!
> The prediction is for 25 F Friday morning, and the "S-word" has been
> mentioned.
> We may have to resort to wearing sleeves as we pull rivets and use the
> dreaded Green ScotchBrite pads.
> Have mercy......
>
> Regards to all who are snowbound,
>
> Zed
>
> do not archive!!!
>
>
>
Message 28
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| Subject: | Re: 701 slats again |
>From www.stolspeed.com
The True Story about Leading Edge Slats
How Zenair 701 & Savannah aircraft fly better with VGs than with Slats!!!
It was way back in 1990, at the SunnFun fly-in at Lakeland, Florida that I first
heard about the possibility of flying a Zenair CH701 without the leading edge
slats. I was very interested in the CH701, so was hanging around the Zenair
display, and there met a couple of CH701 fliers from Colombia. (Usual reaction
at this point is that, ... it must have been for the drug trade, but thats
nonsense this was the days of 532s and early 582s, and the drug syndicates didnt
need to fly over the jungle in two-stroke ultralights, they had the best of
Bell helicopters!) The real reason there were so many CH701s flying there,
is that Columbian men are real macho and always ready for adventure, so this aircraft
suited them very well!
Anyhow, these fellas told me that they had removed their slats and their aircraft
flew better! This was a real surprise, since those leading edge slats are
one of the main distinguishing features of the Zenair CH701! They spoke a bit
of English, and I spoke a bit of Spanish, so I questioned them over and over
again just to be sure, and they assured me that it flew faster without slats,
and landing speed was only a little higher, Lo mismo, mas o menos (more or less
the same)!
Ever since that encounter Ive been telling the story to Zenair CH701 and Storch
fliers, suggesting that they might try flying without their slats, but no one
would, so it had to wait until I had a similar aircraft myself to give it a go.
Now Ive thoroughly tested it out on my Savannah (a clone of the CH701), and
the results are astounding! Ill never put the slats back on. Two Zenair CH701
fliers at our airfield have also removed the slats from their CH701s, and
the results are equally impressive. So we now have a surplus of used slats hung
up in our hangars.
Leading Edge Slats on a Savannah aircraft
Lots of drag and disruption to airflow.......
VGs instead of slats on a Savannah wing
Much cleaner - an excellent STOL wing!
The vast reduction in drag allows all these aircraft to fly considerably faster
for the same power, climb better, glide better, and with the benefit of Vortex
Generators, lift-off and touch-down just as short as with slats, but with more
control.
In summary for my Savannah:
Fast cruise @ 5200 rpm has gone from 79 kt to 85 kt. = + 6 kts
Top speed has gone from 94 kts to 103 kts! = + 9 kts.
Fuel burn @ 75 kts has gone from 17 L/hr to 13 L/hr. = 23.5% less!
Best climb rate @ 55 kts is 100 fpm higher.
Best glide @ 40-45 kts is 100 fpm better.
Stalls (idle power, no flap):
With slats no real stall, just a stable high-descent mush @ less than 30 kts.
Without slats, no VGs* a distinct stall and roll to the left @ 34 kts.
Without slats and with VGs no stall, just a stable mush @ less than 30 kts.
*VGs = Vortex Generators, more about them elsewhere.
L/hr x 0.26 = US Gal/hr.
Kts x 1.15 = mph.
This testing was done in a Savannah aircraft, a kitplane from I.C.P. in Italy, www.icp.it/avio.htm or http://www.skykits.com/ . Its pretty much a clone of a Zenair CH701, same wing profile but a longer wing, and a different tail section. Powered by a 100hp 912ULS, 4-blade Brolga prop pitched for climb (16 blocks), carrying pilot (73kg) and 30 litres fuel.
All tests were done in as similar conditions as possible. It only takes minutes
to remove the slats, so comparison tests with and without were conducted within
one hour of each other, at the same altitude, in calm conditions, at first
light before any thermal activity. Climb and descent figures were timed with
a stopwatch between 2000 and 3000 ft QNH. Stalls and straight and level trials
were conducted at 2000 ft QNH. The with/without tests were done three times
on separate days to re-confirm the figures. The ASI was compared with the GPS
by flying a 120 triangular course and averaging the legs, and found to be 1
kt low at 70 and 80, 1 kt high at 40 and 50, and spot on at 60; these corrections
have been worked into the results. Indicated airspeeds at 30 kts and less
are truly only indicated inherent limitations in the ASI and the pitot at these
low speeds wont necessarily give a true airspeed, but is still adequate for
before and after comparison purposes.
But what about the C of G ?
There was no change at all in the trim setting required for the same cruise speed,
with or without the slats. Which just confirms aerodynamic theory that the
slats arent providing any lift at cruise angles of attack they just allow the
wing to operate at an angle of attack above the normal stalling angle of about
16.
This has solved a mystery that bothered me while building the Savannah, in that
the C of G range quoted in the manual was forward limit = 30% and rear limit
= 38.5%!! Most wings need a rear limit about 30% and a forward limit about 23%
so this seemed to be way too far back?? Mine weighed right in the specified
range, at 31% and 37% so I flew it, and it flew really well as all Savannahs
do, but it certainly didnt feel like a C of G in the 30s - puzzling???? This
was measuring from the leading edge of the slats, with a chord of 1435mm. However,
without the slats and now measuring from the leading edge of the actual
wing itself, instead of from the leading edge of the slats, it calculates to 22%
and 29% of the now 1270mm chord. This is just the sort of range that history
has shown that most wings would call for. So, measuring from the leading
edge of the slats on a slatted wing needs a different consideration
I did try leaving the slats on and covering the gaps top and bottom - not recommended..
This now turned the slats into part of the real lifting surface, so
the actual CofG was then indeed 36%, and it flew like an aft CofG much more pitch
sensitive and not so quick to drop the nose on pulling power. Cruise speed
was the same as for no slats, but stall without VGs was up to 36 kts and much
sharper, probably due to the smaller leading edge radius. I didnt try VGs
on that wing because I wouldnt want to experience deep stalls with such an aft
CofG
Fuel Consumption
The large reduction in fuel consumption was the biggest surprise 23 %! This was
measured accurately and consistently on two long flights (50 hrs each) to Cape
York and to Tasmania, from near Brisbane, Queensland (thats equivalent to
flying from Seattle to Anchorage, then Seattle to El Paso). On the trip to Cape
York with slats on I used 17 litres/hr.; on the trip to Tasmania without slats
I used only 13 litres/hr, averaging 75 kts both trips. On both trips I was
flying in convoy with another Savannah with slats. He used 16 litres/hr both
trips which provides a good reference. The reason I used one litre/hr more
on the Cape York trip, when we both had slats, is that I run a 4-blade prop pitched
for climb, while he has a 3-blade prop pitched for cruise. I used the same
4-blade prop on both trips, and saved 4 litres/hr by leaving the slats behind
a total fuel saving for the trip of $250! I could probably get even better
fuel economy with a 3-blade, but I just love the tremendous take-off grunt
of this 4-blade Brolga!
After seeing my fuel saving on that last trip, the other Savannah owner has now
removed his slats
STOL Performance
The reason I got this Savannah aircraft was for its STOL performance, and I certainly
wasnt disappointed it was always good. I was expecting to lose a little
bit of that STOL performance after removing the slats, so it was a really pleasant
surprise to find that, with the addition of the VGs, it has actually improved!!!
The VGs serve pretty much the same purpose as the slats, but do it
better, with less down-side. The Zenair CH701 owners have found the same improvements.
I can now haul it off the ground sooner, with better control, and accelerate quicker
in ground effect, and then climb away faster. With slats, when I hauled
it back it would jump off just as short, but then wallow along, hanging on the
prop, slowly accelerating behind the drag curve caused by that enormous slot
exposed at that high angle of attack. Now it just jumps up and flies away!
And the climb rate is much improved.
Slow, power-off landings are much easier and safer without the slats. With the
slats on, as the angle of attack increased, the drag increased exponentially,
so that the speed slowed very quickly and the aircraft would drop suddenly and
heavily. Lots of 701's have been bent just this way! Without the drag from
the slats, my aircraft now floats on much more gradually and gently, even if
flaring a bit too high - it's very forgiving!
The Case for Slats
After all that, I'll now present the argument for slats! They're really useful
for power-on landing approaches. Nose way high, hanging on the slats and the
prop, 'dragging' the aircraft in below flying speed, with power controlling the
descent. Can't see where you're going with the nose so high, but easy to do
a spot landing that way - just reduce the power and it'll drop down right now,
no floating on. But watch that you don't get behind the power curve too early
and too high, pray that the engine doesn't stop, and hope that a stray wind
shear doesn't drop a wing at such a critical moment..........
Slats + VGs
I did try VGs along with the original slats. In this case the VGs make no difference
at all, because the slats already give good stall performance, so there's
nothing more that VGs can do. But of course this still leaves all the drag
that the slats produce........
Flaps
Another advantage I didnt expect is that the flaps are now much more effective.
These flaperons provide lots of lift with little drag the descent rate only
goes up 50 fpm from no flap to full flap @ 40 kts. This makes power-off landings
at full flap easy and controllable at about 25 kts touch-down speed. With
the slats on, power-off landings at full flap were risky because the drag built
up so quickly at low speed that, if youre not right close to the ground when
it happens, you come down with impact. Now it just settles on gently. And
this makes sense by aerodynamic theory, in that the slats only do their stuff
at a high angle of attack, while the flaps dramatically reduce the angle of attack
so theyre contradicting each other.. To get any real benefit from the
slats I had to hang on the prop, at a very high angle of attack, and control the
descent rate by power, dragging the aircraft in I dont like that approach
at all; I prefer to fly the aircraft in at idle power.
And this Savannah with VGs instead of leading edge slats does fly remarkably well
now I just love it!!! It now out-performs any Zenair 701 or Savannah with
slats, both for STOL Ops and cruise.
p.s. Now youd have to wonder why the manufacturers didnt discover this long ago,
eh??? Once again it may be the Columbians who provide the answer. They said
that they were told, "......Shh, don't tell anyone, its the slats that sell
these aircraft". Well, Im sure glad they told me about it, and now that Ive
tried it, Ill tell everyone else so we can all benefit!
Now the ongoing story since NatFly 2006
(NatFly is our Australian equivalent of the EAA SunnFun.)
At NatFly 2006, I displayed my Savannah with VGs instead of slats, and with a copy
of this story taped to the side of the aircraft. The interest at NatFly was
enthusiastic, because of course Aussie fliers are quick to pick up on useful
ideas that are proven to work. All over the country now Zenair 701 and Savannah
owners are shedding their slats and going to VGs.
The visiting engineer from the Savannah manufacturing company in Italy looked at
all my test data and then bought their first set of VGs from me! Now we learn
that, after seeing my display at NatFly, and doing their own testing, the Savannah
factory has brought out a new model, the 'Savannah VG', with a new leading
edge and vortex generators instead of leading edge slats. So theyre still
open to new ideas and quick on the uptake, and now theyre producing an even
better aircraft!
Those of us with original Savannahs who have just removed our slats and added VGs
to the original wing are getting very much the same performance figures as
published for the companys new leading edge with VGs. So Im eagerly awaiting
the new Savannah VG model, so I can do some comparison testing against mine with
just the original wing with VGs instead of slats. The first of the new models
are due out here in August, and a friend nearby will probably be the first
to finish building one. Hes a good STOL flier so we should be able to do some
really interesting comparisons. I reckon theyre going to be very much the
same.
The Savannah manufacturing company is offering an upgrade kit, with a replacement
leading edge and VGs. I sure wouldnt be ordering that upgrade kit for $1000
until I see some really noticeable improvement in performance. To take the
wings off, drill out all those important rivets in the spar (and end up with oblong
and oversize holes), and then fight get that new skin (with an even sharper
radius) installed so that the holes line up again, then paint it all again,
Id have to be sure there was a really significant gain to be had Theres certainly
nothing at all wrong with my wing as it is I just love it! Best to wait
and see I reckon well probably know well before Christmas and will publish
the results in this website.
In the meantime, join the rest of us whove done it, and pull those mongrel slats
off and add some VGs, and fly better!
You can hedge your bets by leaving the slat brackets on the wing, but a couple
of us seemed to notice an improvement without them. Hans detected a big difference
for his 701, but the comparison tests couldnt be done in exactly the same
conditions, and of course he cant go back and do another before test once theyve
been cut off.. So Im making pretend brackets that we can tape back onto
our wings to do all the comparisons again. As you can see, I certainly believe
in thorough flight testing to get valid results. Update Oct 06: Results just
in from a retired CASA engineer who has done considerable testing. He flew
his Savannah for quite awhile with the brackets before removing them, and has
now noticed a considerable improvement in lateral stability and benign stall
charcteristics. So better remove the brackets for best results.
Im often asked just how to cut those brackets off with least hassles. I used one
of those very thin cut-off discs in a small angle grinder. Just hold it at
a 45 angle and carefully cut a groove on each side as close in as possible.
Dont try to cut right through once there is a suitable groove on each side, you
can flex the bracket a couple of times and break it off. Then just grind out
any portions that sit proud of the wing. There are five rivets alongside the
bracket which look really crude once the slat is off. I drilled them out and
put countersunk rivets instead. I used polyester autobody filler to heal the
scar, but epoxy filler would probably be better.
I have a fetish for STOL Ops, and this Savannah with VGs is just ideal. Its performing
STOL so well now that I just cant help showing off all the time, even
on long runways!
240hours in the first year, and its all been a blast!
For NatFly I had imported some VGs from the USA, and they sold to Zenair 701, Savannah,
Bingo, Lightwing, Skyfox and Jabiru owners. Since then Ive been doing
lots more testing and comparison, and have come up with the new design of Feathers
VGs that are described elsewhere in this website.
Fair skies and tail winds.
JG
Aug 06
Do Not Archive
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=77730#77730
Message 29
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Hey Ron, I know where Rotan is , I was BORN there, not much in the area
then except cotton fields,dust,rattlesnakes and oil wells. LOW&SLOW
John
----- Original Message -----
From: ron wehba
To: zenith-list@matronics.com
Sent: Tuesday, November 28, 2006 9:31 PM
Subject: Re: Zenith-List: Enough!!!
hi zed, ron here in rotan, north west of abilene, we are gittin' out a
da
way of it , going to canton for the next few days. wind might not even
be
blowing there,, stay warm
----- Original Message -----
From: "Zed Smith" <zsmith3rd@earthlink.net>
To: <zenith-list@matronics.com>
Sent: Tuesday, November 28, 2006 4:21 PM
Subject: Zenith-List: Enough!!!
Message 30
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Zed I live in Texas about 30 miles from the Oklahoma/Texas border I'll let you
know when it arrives so you can get ready.
Danny
Van Alstyne
do not archive
-----Original Message-----
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com]On Behalf Of Zed Smith
Sent: Tuesday, November 28, 2006 4:22 PM
Subject: Zenith-List: Enough!!!
Will you guys in the northern latitudes just cut it out??
North Texas has enjoyed mild temps in the mid 70's for two or three months.....now
we are told that somebody north of Oklahoma has left a gate open.
It is 73 F as I type this plea for sanity.....close those gates, fellows! The
prediction is for 25 F Friday morning, and the "S-word" has been mentioned.
We may have to resort to wearing sleeves as we pull rivets and use the dreaded
Green ScotchBrite pads.
Have mercy......
Regards to all who are snowbound,
Zed
do not archive!!!
Message 31
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| Subject: | Re: 701 slats again |
Pictures please ..also from what I have read in these posts of late just
removing the slats would seriously alter the profile of the wing and that it
was designed from a wing with no slat but shaped as if they were not a
seperate item and then Chris Heintz move the "slat" part forward thus giving
a slot. So are the 701 owners at your field using just the present wing
less the slots without altering the wing itself??? Did they have to alter CG
etc??? More explanation and a few pics would certainly help clear this up..
Thanks,
701 Scratch Builder ... not to the wings yet!
----- Original Message -----
From: "secatur" <appraise1@bigpond.com>
Sent: Tuesday, November 28, 2006 10:58 PM
Subject: Zenith-List: Re: 701 slats again
>
>>From www.stolspeed.com
>
> The True Story about Leading Edge Slats
>
> How Zenair 701 & Savannah aircraft fly better with VGs than with Slats!!!
>
> It was way back in 1990, at the Sun?TnFun fly-in at Lakeland, Florida
> that I first heard about the possibility of flying a Zenair CH701 without
> the leading edge slats. I was very interested in the CH701, so was
> hanging around the Zenair display, and there met a couple of CH701 fliers
> from Colombia. (Usual reaction at this point is that, ?o... it must have
> been for the drug trade??, but that?Ts nonsense ?" this was the days
> of 532?Ts and early 582?Ts, and the drug syndicates didn?Tt need to fly
> over the jungle in two-stroke ultralights, they had the best of Bell
> helicopters!) The real reason there were so many CH701?Ts flying there,
> is that Columbian men are real macho and always ready for adventure, so
> this aircraft suited them very well!
>
> Anyhow, these fellas told me that they had removed their slats and their
> aircraft flew better! This was a real surprise, since those leading edge
> slats are one of the main distinguishing features of the Zenair CH701!
> They spoke a bit of English, and I spoke a bit of Spanish, so I questioned
> them over and over again just to be sure, and they assured me that it flew
> faster without slats, and landing speed was only a little higher, ?o?Lo
> mismo, mas o menos?? (?o?more or less the same?)!
>
> Ever since that encounter I?Tve been telling the story to Zenair CH701
> and Storch fliers, suggesting that they might try flying without their
> slats, but no one would, so it had to wait until I had a similar aircraft
> myself to give it a go. Now I?Tve thoroughly tested it out on my
> Savannah (a clone of the CH701), and the results are astounding! I?Tll
> never put the slats back on. Two Zenair CH701 fliers at our airfield have
> also removed the slats from their CH701s, and the results are equally
> impressive. So we now have a surplus of used slats hung up in our
> hangars??.
>
>
> Leading Edge Slats on a Savannah aircraft
> Lots of drag and disruption to airflow.......
>
>
> VGs instead of slats on a Savannah wing
> Much cleaner - an excellent STOL wing!
>
>
> The vast reduction in drag allows all these aircraft to fly considerably
> faster for the same power, climb better, glide better, and with the
> benefit of Vortex Generators, lift-off and touch-down just as short as
> with slats, but with more control.
>
> In summary for my Savannah:
>
> Fast cruise @ 5200 rpm has gone from 79 kt to 85 kt. = + 6 kts
> Top speed has gone from 94 kts to 103 kts! = + 9 kts.
> Fuel burn @ 75 kts has gone from 17 L/hr to 13 L/hr. = 23.5% less!
> Best climb rate @ 55 kts is 100 fpm higher.
> Best glide @ 40-45 kts is 100 fpm better.
>
> Stalls (idle power, no flap):
> With slats ?" no real stall, just a stable high-descent mush @ less than
> 30 kts.
> Without slats, no VGs* ?" a distinct stall and roll to the left @ 34 kts.
> Without slats and with VGs ?" no stall, just a stable mush @ less than 30
> kts.
>
> *VGs = Vortex Generators, more about them elsewhere.
> L/hr x 0.26 = US Gal/hr.
> Kts x 1.15 = mph.
>
> This testing was done in a ?~Savannah?T aircraft, a kitplane from I.C.P.
> in Italy, www.icp.it/avio.htm or http://www.skykits.com/ . It?Ts pretty
> much a clone of a Zenair CH701, same wing profile but a longer wing, and a
> different tail section. Powered by a 100hp 912ULS, 4-blade Brolga prop
> pitched for climb (16 blocks), carrying pilot (73kg) and 30 litres fuel.
>
> All tests were done in as similar conditions as possible. It only takes
> minutes to remove the slats, so comparison tests with and without were
> conducted within one hour of each other, at the same altitude, in calm
> conditions, at first light before any thermal activity. Climb and descent
> figures were timed with a stopwatch between 2000 and 3000 ft QNH. Stalls
> and straight and level trials were conducted at 2000 ft QNH. The
> with/without tests were done three times on separate days to re-confirm
> the figures. The ASI was compared with the GPS by flying a 120
> triangular course and averaging the legs, and found to be 1 kt low at 70
> and 80, 1 kt high at 40 and 50, and spot on at 60; these corrections have
> been worked into the results. Indicated airspeeds at 30 kts and less are
> truly only ?~indicated?T ?" inherent limitations in the ASI and the
> pitot at these low speeds won?Tt necessarily give a true airspeed, but is
> still adequate for ?~before and after?T comparison p!
> urposes.
>
> But what about the C of G ?
>
> There was no change at all in the trim setting required for the same
> cruise speed, with or without the slats. Which just confirms aerodynamic
> theory that the slats aren?Tt providing any lift at cruise angles of
> attack ?" they just allow the wing to operate at an angle of attack above
> the normal stalling angle of about 16.
>
> This has solved a mystery that bothered me while building the Savannah, in
> that the C of G range quoted in the manual was forward limit = 30% and
> rear limit = 38.5%!! Most wings need a rear limit about 30% and a forward
> limit about 23% so this seemed to be way too far back?? Mine weighed
> right in the specified range, at 31% and 37% so I flew it, and it flew
> really well as all Savannahs do, but it certainly didn?Tt feel like a C
> of G in the 30?Ts - puzzling???? This was measuring from the leading
> edge of the slats, with a chord of 1435mm. However, without the slats and
> now measuring from the leading edge of the actual wing itself, instead of
> from the leading edge of the slats, it calculates to 22% and 29% of the
> now 1270mm chord. This is just the sort of range that history has shown
> that most wings would call for. So, measuring from the leading edge of
> the slats on a slatted wing needs a different consideration??
>
> I did try leaving the slats on and covering the gaps top and bottom - not
> recommended?.. This now turned the slats into part of the real lifting
> surface, so the actual CofG was then indeed 36%, and it flew like an aft
> CofG ?" much more pitch sensitive and not so quick to drop the nose on
> pulling power. Cruise speed was the same as for no slats, but stall
> without VGs was up to 36 kts and much sharper, probably due to the smaller
> leading edge radius. I didn?Tt try VGs on that wing because I wouldn?Tt
> want to experience deep stalls with such an aft CofG??
>
> Fuel Consumption
>
>
> The large reduction in fuel consumption was the biggest surprise ?" 23 %!
> This was measured accurately and consistently on two long flights (50 hrs
> each) to Cape York and to Tasmania, from near Brisbane, Queensland
> (that?Ts equivalent to flying from Seattle to Anchorage, then Seattle to
> El Paso). On the trip to Cape York with slats on I used 17 litres/hr.; on
> the trip to Tasmania without slats I used only 13 litres/hr, averaging 75
> kts both trips. On both trips I was flying in convoy with another
> Savannah with slats. He used 16 litres/hr both trips which provides a
> good reference. The reason I used one litre/hr more on the Cape York
> trip, when we both had slats, is that I run a 4-blade prop pitched for
> climb, while he has a 3-blade prop pitched for cruise. I used the same
> 4-blade prop on both trips, and saved 4 litres/hr by leaving the slats
> behind ?" a total fuel saving for the trip of $250! I could probably get
> even better fuel economy with a 3-blade, but I just !
> love the tremendous take-off ?~grunt?T of this 4-blade Brolga!
>
> After seeing my fuel saving on that last trip, the other Savannah owner
> has now removed his slats??
>
> STOL Performance
>
> The reason I got this Savannah aircraft was for it?Ts STOL performance,
> and I certainly wasn?Tt disappointed ?" it was always good. I was
> expecting to lose a little bit of that STOL performance after removing the
> slats, so it was a really pleasant surprise to find that, with the
> addition of the VGs, it has actually improved!!! The VGs serve pretty
> much the same purpose as the slats, but do it better, with less down-side.
> The Zenair CH701 owners have found the same improvements.
>
> I can now haul it off the ground sooner, with better control, and
> accelerate quicker in ground effect, and then climb away faster. With
> slats, when I hauled it back it would jump off just as short, but then
> wallow along, hanging on the prop, slowly accelerating behind the drag
> curve caused by that enormous slot exposed at that high angle of attack.
> Now it just jumps up and ?~flies?T away! And the climb rate is much
> improved.
>
> Slow, power-off landings are much easier and safer without the slats.
> With the slats on, as the angle of attack increased, the drag increased
> exponentially, so that the speed slowed very quickly and the aircraft
> would drop suddenly and heavily. Lots of 701's have been bent just this
> way! Without the drag from the slats, my aircraft now floats on much more
> gradually and gently, even if flaring a bit too high - it's very
> forgiving!
>
> The Case for Slats
>
> After all that, I'll now present the argument for slats! They're really
> useful for power-on landing approaches. Nose way high, hanging on the
> slats and the prop, 'dragging' the aircraft in below flying speed, with
> power controlling the descent. Can't see where you're going with the nose
> so high, but easy to do a spot landing that way - just reduce the power
> and it'll drop down right now, no floating on. But watch that you don't
> get behind the power curve too early and too high, pray that the engine
> doesn't stop, and hope that a stray wind shear doesn't drop a wing at such
> a critical moment..........
>
> Slats + VGs
>
> I did try VGs along with the original slats. In this case the VGs make no
> difference at all, because the slats already give good stall performance,
> so there's nothing more that VGs can do. But of course this still leaves
> all the drag that the slats produce........
>
> Flaps
>
> Another advantage I didn?Tt expect is that the flaps are now much more
> effective. These flaperons provide lots of lift with little drag ?" the
> descent rate only goes up 50 fpm from no flap to full flap @ 40 kts. This
> makes power-off landings at full flap easy and controllable at about 25
> kts touch-down speed. With the slats on, power-off landings at full flap
> were risky because the drag built up so quickly at low speed that, if
> you?Tre not right close to the ground when it happens, you come down with
> impact?. Now it just settles on gently. And this makes sense by
> aerodynamic theory, in that the slats only do their stuff at a high angle
> of attack, while the flaps dramatically reduce the angle of attack ?" so
> they?Tre contradicting each other?.. To get any real benefit from the
> slats I had to ?~hang?T on the prop, at a very high angle of attack, and
> control the descent rate by power, ?~dragging?T the aircraft in ?" I
> don?Tt like that approach at all; I pr!
> efer to ?~fly?T the aircraft in at idle power.
>
> And this Savannah with VGs instead of leading edge slats does ?~fly?T
> remarkably well now ?" I just love it!!! It now out-performs any Zenair
> 701 or Savannah with slats, both for STOL Ops and cruise.
>
> p.s. ?" Now you?Td have to wonder why the manufacturers didn?Tt
> discover this long ago, eh??? Once again it may be the Columbians who
> provide the answer. They said that they were told, "......Shh, don't tell
> anyone, it?Ts the slats that sell these aircraft??". Well, I?Tm
> sure glad they told me about it, and now that I?Tve tried it, I?Tll
> tell everyone else so we can all benefit!
>
> Now the ongoing story since NatFly 2006
>
> (NatFly is our Australian equivalent of the EAA Sun?TnFun.)
> At NatFly 2006, I displayed my Savannah with VGs instead of slats, and
> with a copy of this story taped to the side of the aircraft. The interest
> at NatFly was enthusiastic, because of course Aussie fliers are quick to
> pick up on useful ideas that are proven to work. All over the country now
> Zenair 701 and Savannah owners are shedding their slats and going to VGs.
>
> The visiting engineer from the Savannah manufacturing company in Italy
> looked at all my test data and then bought their first set of VGs from me!
> Now we learn that, after seeing my display at NatFly, and doing their own
> testing, the Savannah factory has brought out a new model, the 'Savannah
> VG', with a new leading edge and vortex generators instead of leading edge
> slats. So they?Tre still open to new ideas and quick on the uptake, and
> now they?Tre producing an even better aircraft!
>
> Those of us with original Savannahs who have just removed our slats and
> added VGs to the original wing are getting very much the same performance
> figures as published for the company?Ts new leading edge with VGs. So
> I?Tm eagerly awaiting the new Savannah ?~VG?T model, so I can do some
> comparison testing against mine with just the original wing with VGs
> instead of slats. The first of the new models are due out here in August,
> and a friend nearby will probably be the first to finish building one.
> He?Ts a good STOL flier so we should be able to do some really
> interesting comparisons. I reckon they?Tre going to be very much the
> same??.
>
> The Savannah manufacturing company is offering an upgrade kit, with a
> replacement leading edge and VGs. I sure wouldn?Tt be ordering that
> upgrade kit for $1000 until I see some really noticeable improvement in
> performance. To take the wings off, drill out all those important rivets
> in the spar (and end up with oblong and oversize holes), and then fight
> get that new skin (with an even sharper radius) installed so that the
> holes line up again, then paint it all again, I?Td have to be sure there
> was a really significant gain to be had?? There?Ts certainly nothing
> at all wrong with my wing as it is ?" I just love it! Best to wait and
> see I reckon ?" we?Tll probably know well before Christmas and will
> publish the results in this website.
>
> In the meantime, join the rest of us who?Tve done it, and pull those
> mongrel slats off and add some VGs, and fly better!
>
> You can hedge your bets by leaving the slat brackets on the wing, but a
> couple of us seemed to notice an improvement without them. Hans detected
> a big difference for his 701, but the comparison tests couldn?Tt be done
> in exactly the same conditions, and of course he can?Tt go back and do
> another ?~before?T test once they?Tve been cut off?.. So I?Tm
> making ?~pretend?T brackets that we can tape back onto our wings to do
> all the comparisons again. As you can see, I certainly believe in
> thorough flight testing to get valid results. Update Oct 06: Results
> just in from a retired CASA engineer who has done considerable testing.
> He flew his Savannah for quite awhile with the brackets before removing
> them, and has now noticed a considerable improvement in lateral stability
> and benign stall charcteristics. So better remove the brackets for best
> results.
>
> I?Tm often asked just how to cut those brackets off with least hassles.
> I used one of those very thin cut-off discs in a small angle grinder.
> Just hold it at a 45 angle and carefully cut a groove on each side as
> close in as possible. Don?Tt try to cut right through ?" once there is
> a suitable groove on each side, you can flex the bracket a couple of times
> and break it off. Then just grind out any portions that sit proud of the
> wing. There are five rivets alongside the bracket which look really crude
> once the slat is off. I drilled them out and put countersunk rivets
> instead. I used polyester autobody filler to heal the scar, but epoxy
> filler would probably be better.
>
> I have a fetish for STOL Ops, and this Savannah with VGs is just ideal.
> It?Ts performing STOL so well now that I just can?Tt help showing off
> all the time, even on long runways!
> 240hours in the first year, and it?Ts all been a blast!
>
> For NatFly I had imported some VGs from the USA, and they sold to Zenair
> 701, Savannah, Bingo, Lightwing, Skyfox and Jabiru owners. Since then
> I?Tve been doing lots more testing and comparison, and have come up with
> the new design of Feathers VGs that are described elsewhere in this
> website.
>
>
> Fair skies and tail winds.
>
> JG
> Aug 06
>
> Do Not Archive
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=77730#77730
>
>
>
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| Subject: | Re: 701 slats again |
READ previous post, or go to www.stolspeed.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=77746#77746
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| Subject: | RE: 701 slats again |
I've been flying my 701 for 475 hrs total,175 hrs without slats, so I
think maybe I should comment on this thread. I was the first 701 flyer
in Australia to remove the slats ,after seeing the results that the
savannahs got. See www.stolspeed.com. I must say that I like it much
better without the slats and will never change back!!
Since then two other 701's at our airfield have removed their slats,and
I have flown their aircraft-same result.
To answer some of those specific dire predictions:
>my take is that the C of G and the centre of pressure would move
back,the Cp more so causing a nose heavy pitch moment at all speeds and
angles of attack<
Not so in real life..... before I took the slats off I did a test flight
and set the trim to neutral cruise. About one hour later I did another
test flight with the slats off, same conditions,same load. no change at
all in cruise trim! Take-off,climb,decent,and landing,all felt balanced
and correct...
>I would expect all stall speeds to increase with the clean wing<
With the clean wing,yes of course the stall speed increased and became
more abrupt,but with the VG's it came back very much like with slats,and
angle of attack much the same as with slats.
>and top speed to probably remain the same or decrease because of the
blunt leading edge<
Not so- top speed and cruise speed definitely increased without the
slats and fuel consumption really decreased for the same cruise
speed.15%.The blunt leading edge doesn't seem to effect the speed in
this speed range.You would think so,but the Savannah with that same
blunt profile as the 701 goes pretty much the same speed as the new
"finer" leading edge that the Savannah put on their new "VG" model .
>adding VG"s should delay the stall but should also increase drag?<
No they do not increase drag-see the Updates page in www.stolspeed.com.
>if one wants to remove the slats from the airfoil design, the original
airfoil can be recovered by simply covering the slots with sheet metal
that matches the airfoil contour
Be careful about that one! See the slats vs. VG's page, C of G section,
in www.stolspeed.com. When original built with slats, 95 litre wing
tanks,and 912 S,my loaded Cof G calculated at 477 mm aft of the slat
leading edge,1433 mm cord = 33% m.a.c This number would seem quite far
aft by conventional practice,but it sure didn't fly as if it had a aft C
of G .removing the slats moved the leading edge aft 160 mm , so the same
C of G position was now located 317 mm from the new leading edge, with
the cord now 1270 mm = 25% m.a.c. , which is right in the range
recommended for any conventional wing. I recently did a new weight and
balance on very good scales-
without slats =26%m.a.c, loaded up for travel- full fuel ( wing
tanks),20 kg baggage , 40 litres of fuel in pax seat - 503 kg ( 1107
lbs).It flies just perfect like this.
Well I have tried no slats and I wouldn't go back, no way! And it's not
as if I am easily influenced by other people's claims- I'm a sceptical,
independent-minded Dutchman,ex-Royal Dutch Air Force. I fly my plane
hard,and practice STOL landings all the time,so I have a really good
feel for it at all speeds. Always doing glide approach and idle power
landings-That is the real test of a well balanced aircraft.
Hans van Santen
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