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johngilpin
Joined: 23 Mar 2011
Posts: 93
Location: 004
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 Posted: Sat May 11, 2013 12:26 am Post subject: Slats |
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Gday,
I regret being so slow to reply to this thread, but Ive been occupied elsewhere. Not wanting to prolong it, and I do hope this is the last time that Ill feel the need to post on this subject. But I feel that I must respond to a series of mis-truths that are so often repeated without basis. This is based only on real life flight testing and experience. Sorry its so long, but it needs to be said..
Taking the slats off of the 701 wing makes a completely different airfoil so you have become test pilots not experimental pilots
Not so now. The Colombians who were the first to take their slats off were the test pilots, but that was 24 years ago, and theyve been flying that way ever since... I did the experimenting and evaluation 7 years ago, and since then have 1000hrs of flying without slats, much of that touring outback Australia, including countless STOL ops from rough off-field locations, and never felt the need for slats. Hans now has 800hrs since removing his slats, and three other aircraft at our airfield would have about another 500hrs, with no one wanting to change back. Ron in Arizona has many, many hours experience each way, and much prefers his 701 without slats, as he has stated on this forum. J.S. in Mississippi, whos a high time professional pilot in a wide variety of aircraft, and a very critical test pilot, (he doesnt sugar coat anything), was initially sceptical, and set out to disprove my claims, but found out they were true, and now his slats hang in the roof of his hangar. So were now way past the test pilot and experimental stage; this is now a proven and established configuration.
the basic airfoil has about a 1.3 coefficient of lift. It's the slats that make the difference
Have a look at this video of Hans taking off without slats, only a light breeze and a warm day, (not like the frigid air at Valdez).
http://www.youtube.com/watch?v=Y4_GsoN9hA8
To lift that weight at that speed, thats a whole lot more than 1.3 CofL. J.S. stated that his tests showed that slats gave him about 10% shorter T/O roll, but then as he said, for a 701 thats a difference of about 6-10 feet big deal.
Who needs a shorter take-off run than Hans just demonstrated??
Slats double the lift of a given airfoil
That is so for some wings, but careful, repeatable, flight testing shows its definitely not true for the 701! Let the writers of the books explain why not. But there are observations I can make from personal experience with other slatted aircraft including the Helio Courier, Rallye, and the Pegastol wing for the 701. All of them have slim, low-camber wings that are optimized for cruise when the slats are retracted. When those slats are deployed they not only move forward to open the slot, but also move considerably downwards, which has the effect of increasing the effective camber of the wing, and thus greatly increasing the CofL. But the 701 starts with a highly cambered wing with an already high CofL, and the slats are fixed directly in front of it, thus not increasing the effective camber and CofL any further. (Actually, the 701 did originally have the slats mounted with their leading edge below the wing, but that caused such turbulence and instability at fast cruise that they were moved upwards to where they are now). Fixed slats are a difficult compromise at best, and experience and testing shows that very little CofL is lost in removing them from a 701.
Taking the slats off of the 701 wing make a completely different airfoil
Thats correct, but its notanentirely unknown airfoil. We were flying with very similar airfoils on ultralights 20+ years ago, and they had very forgiving stall characteristics and good slow speed flight.
Who would have thought this airfoil would be so good for both stall and cruise on the 701?? I certainly didnt expect that, so even before I first removed the slats Id made new nose ribs to match the contour including the slats. But after closing over the slots temporarily and not liking the result, and having tried the bare wing without slats and being impressed with the flight characteristics, those ribs hung in my workshop for years until they finally went for scrap
Some call it a blunt leading edge, but its not so, its just nice and fully rounded (like a good woman). That fully rounded leading edge gives excellent stall characteristics and a benign pitching moment, just what you need for flying safely at minimum speed. The surprising part is that it causes so little extra drag at cruise speed; about 1.5kts as compared to a NACA 65018 leading edge. But the fully rounded leading edge gives a 2kts slower stall speed and a much more docile stall characteristic, so Im happy to live with that for my purposes.
VGs only make a poor performing airfoil work better
Not so. VGs dont improve a wing, they just improve the airflow over any wing. They keep the air flowing in a contiguous sheet, close to the wing surface, and help prevent disturbances from spreading. This helps any wing perform to its best. The fully rounded 701 wing is already an excellent airfoil for STOL purposes even without VGs, but they do help control the airflow to make it hang on even slower.
why any of the "Slat Removal Group bothered to build the 701 in the first place
Thats really easy because the 701 is such an excellent little aircraft! (other than the slats) Great performance from an excellent wing, excellent controls, and excellent landing gear. That all-metal construction is rugged and durable, and so easy to work with. It would have to be the easiest aircraft to build from kit or plans, so its quite affordable. Its not sleek and sexy, but its durable and practical, like a good old 4WD, and thats just the sort of aircraft I want. I wouldnt want any of those delicate and fragile fabric or plastic aircraft. I consider the original 701 with slats to equate to a WW2 Willys Jeep, a brilliant new concept for its purpose at that time, but tedious on the highway these days. Without the slats, and with a couple of other improvement mods, that old Willys 701 now equates to a modern day Suzuki 4WD, fine on the highway and still just as good off-road. Thats what I want in an aircraft, and I just love it!
Whats with you guys who object so strongly to removing slats, when you have no real experience of the comparison?? Keep them on yourself by all means, but please dont try to inhibit others the freedom to make their own choices based on the considerable experience that so many of us have already demonstrated. Its evolution in action, and thats what makes progress. If a fella like Ernest can get the cruise capability that hes wanting, without having to sell his good little aircraft and buy another, (at much hassle and probably at a loss), then he should be encouraged to try the easy and proven option first
As my old Dad used to say, Take everybodys advice, then do as you darn well please
JG
[quote][b]
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rvickski(at)yahoo.com
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| Posted: Sat May 11, 2013 2:34 am Post subject: Slats |
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JG,
Thanks for the good work and posting real life results.
I would like your considered opinion in regards to using the full 65018 nose rib and leading edge.
The CG range being 20-35% in the original configuration, from front edge of slat to rear edge of flaperon. Does or did you notice any aft CG tendencies without the slat?
My reason for asking is that my firewall forward weight will exceed 200 pounds and I do not want to create a compounding situation running slatless.
Roy Szarafinski www.roysgarage.com
roy(at)roysgarage.com (roy(at)roysgarage.com)
rvickski(at)yahoo.com (rvickski(at)yahoo.com)
On May 11, 2013, at 4:25 AM, JC Gilpin <j.gilpin(at)bigpond.com (j.gilpin(at)bigpond.com)> wrote:
[quote]
Gday,
I regret being so slow to reply to this thread, but I’ve been occupied elsewhere. Not wanting to prolong it, and I do hope this is the last time that I’ll feel the need to post on this subject. But I feel that I must respond to a series of mis-truths that are so often repeated without basis. This is based only on real life flight testing and experience. Sorry it’s so long, but it needs to be said…..
…Taking the slats off of the 701 wing makes a completely different airfoil so you have become test pilots not experimental pilots…
Not so now. The Colombians who were the first to take their slats off were the test pilots, but that was 24 years ago, and they’ve been flying that way ever since... I did the experimenting and evaluation 7 years ago, and since then have 1000hrs of flying without slats, much of that touring outback Australia, including countless STOL ops from rough off-field locations, and never felt the need for slats. Hans now has 800hrs since removing his slats, and three other aircraft at our airfield would have about another 500hrs, with no one wanting to change back. Ron in Arizona has many, many hours experience each way, and much prefers his 701 without slats, as he has stated on this forum. J.S. in Mississippi, who’s a high time professional pilot in a wide variety of aircraft, and a very critical test pilot, (he doesn’t ‘sugar coat’ anything), was initially sceptical, and set out to disprove my claims, but found out they were true, and now his slats hang in the roof of his hangar. So we’re now way past the test pilot and experimental stage; this is now a proven and established configuration.
…the basic airfoil has about a 1.3 coefficient of lift. It's the slats that make the difference…
Have a look at this video of Hans taking off without slats, only a light breeze and a warm day, (not like the frigid air at Valdez).
http://www.youtube.com/watch?v=Y4_GsoN9hA8
To lift that weight at that speed, that’s a whole lot more than 1.3 CofL…. J.S. stated that his tests showed that slats gave him about 10% shorter T/O roll, but then as he said, “…for a 701 that’s a difference of about 6-10 feet – big deal…”.
Who needs a shorter take-off run than Hans just demonstrated??
…Slats double the lift of a given airfoil…
That is so for some wings, but careful, repeatable, flight testing shows it’s definitely not true for the 701! Let the writers of the books explain why not…. But there are observations I can make from personal experience with other slatted aircraft including the Helio Courier, Rallye, and the Pegastol wing for the 701. All of them have slim, low-camber wings that are optimized for cruise when the slats are retracted. When those slats are deployed they not only move forward to open the slot, but also move considerably downwards, which has the effect of increasing the effective camber of the wing, and thus greatly increasing the CofL. But the 701 starts with a highly cambered wing with an already high CofL, and the slats are fixed directly in front of it, thus not increasing the effective camber and CofL any further. (Actually, the 701 did originally have the slats mounted with their leading edge below the wing, but that caused such turbulence and instability at fast cruise that they were moved upwards to where they are now). Fixed slats are a difficult compromise at best, and experience and testing shows that very little CofL is lost in removing them from a 701.
…Taking the slats off of the 701 wing make a completely different airfoil…
That’s correct, but it’s not an entirely unknown airfoil. We were flying with very similar airfoils on ultralights 20+ years ago, and they had very forgiving stall characteristics and good slow speed flight.
Who would have thought this airfoil would be so good for both stall and cruise on the 701?? I certainly didn’t expect that, so even before I first removed the slats I’d made new nose ribs to match the contour including the slats. But after closing over the slots temporarily and not liking the result, and having tried the bare wing without slats and being impressed with the flight characteristics, those ribs hung in my workshop for years until they finally went for scrap
Some call it a ‘blunt’ leading edge, but it’s not so, it’s just ‘nice and fully rounded’ (like a good woman). That ‘fully rounded’ leading edge gives excellent stall characteristics and a benign pitching moment, just what you need for flying safely at minimum speed. The surprising part is that it causes so little extra drag at cruise speed; about 1.5kts as compared to a NACA 65018 leading edge. But the ‘fully rounded’ leading edge gives a 2kts slower stall speed and a much more docile stall characteristic, so I’m happy to live with that for my purposes.
…VGs only make a poor performing airfoil work better…
Not so. VGs don’t improve a wing, they just improve the airflow over any wing. They keep the air flowing in a contiguous sheet, close to the wing surface, and help prevent disturbances from spreading. This helps any wing perform to it’s best. The ‘fully rounded’ 701 wing is already an excellent airfoil for STOL purposes even without VGs, but they do help control the airflow to make it hang on even slower.
…why any of the "Slat Removal Group” bothered to build the 701 in the first place…
That’s really easy – because the 701 is such an excellent little aircraft! (other than the slats) Great performance from an excellent wing, excellent controls, and excellent landing gear. That all-metal construction is rugged and durable, and so easy to work with. It would have to be the easiest aircraft to build from kit or plans, so it’s quite affordable. It’s not sleek and sexy, but it’s durable and practical, like a good old 4WD, and that’s just the sort of aircraft I want. I wouldn’t want any of those delicate and fragile fabric or plastic aircraft. I consider the original 701 with slats to equate to a WW2 Willys Jeep, a brilliant new concept for it’s purpose at that time, but tedious on the highway these days. Without the slats, and with a couple of other improvement mods, that old ‘Willys’ 701 now equates to a modern day Suzuki 4WD, fine on the highway and still just as good off-road. That’s what I want in an aircraft, and I just love it!
What’s with you guys who object so strongly to removing slats, when you have no real experience of the comparison?? Keep them on yourself by all means, but please don’t try to inhibit others the freedom to make their own choices based on the considerable experience that so many of us have already demonstrated. It’s evolution in action, and that’s what makes progress. If a fella like Ernest can get the cruise capability that he’s wanting, without having to sell his good little aircraft and buy another, (at much hassle and probably at a loss), then he should be encouraged to try the easy and proven option first…
As my old Dad used to say, “…Take everybody’s advice, then do as you darn well please…”
JG
| Quote: |
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st">http://www.matronics.com/Navigator?Zenith701801-List
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cs.com
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matronics.com/contribution
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rvickski(at)yahoo.com
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| Posted: Sat May 11, 2013 2:52 am Post subject: Slats |
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Correction, should read; did you notice any forward CG tendencies?
Sorry about that, my brain got in front of my thinker.
Roy Szarafinski
www.roysgarage.com
roy(at)roysgarage.com
rvickski(at)yahoo.com
On May 11, 2013, at 6:33 AM, Roy Szarafinski <rvickski(at)yahoo.com> wrote:
| Quote: | JG,
Thanks for the good work and posting real life results.
I would like your considered opinion in regards to using the full 65018 nose rib and leading edge.
The CG range being 20-35% in the original configuration, from front edge of slat to rear edge of flaperon. Does or did you notice any aft CG tendencies without the slat?
|
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rockiedog2
Joined: 03 Mar 2010
Posts: 19
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| Posted: Sun May 12, 2013 3:20 pm Post subject: Slats |
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I've been in aviation a long time and have met all types, but never one more competent and ethical than John Gilpin. If it's on his website you can believe it.
As far as the slat/vg comparison goes...there is no question that the VGs outperform the slats in all respects but the previously mentioned very small takeoff roll penalty(my experience). The plane is much more efficient in all other respects with the slats replaced by vgs. I realize there are some who will never accept the facts because they have a closed mind or some similar reason...that's certainly their choice but also their loss. Generally, those who reject the VGs have no experience whatsoever with them on the 701.
Best to all
Joe Spencer
[quote][b]
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n801bh(at)netzero.com
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| Posted: Sun May 12, 2013 6:16 pm Post subject: Slats |
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I will be a total believer when John Gilpin designs, test flys and markets his own plane based on slat-less wings. Until then he is a VG salesman who wants to sell his product..... Ps... I have installed the Zenith VG's on the horizontal stabilizer of my 801 and I admit it made a big difference............ But.... my horizontal stabilizer didn't have slats on it to start with so I cannot draw any conclusions.... YMMV..
do not archive
Ben Haas
N801BH
www.haaspowerair.com
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infow(at)shaw.ca
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| Posted: Sun May 12, 2013 7:40 pm Post subject: Slats |
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I guess what you are saying is JG does not have the facts! Well Zenith sure took notice of the
fact that JG was the one that did the research by placing them on the leading edge of the
elevator... so much notice they copied them. Selling VG's is not something that you will get
rich from... and I don't know why he does it??? You do not believe what JG does is fact... no
one is asking you too, who cares! Kind of piss's me off when people start making these kind
of statements with no facts. The research is all on his web site... read it, slat less
wing/VG's, longer wing, beanie mod, streamlined stab/elev... backed up with data! So lets not
bury our head in the sand... especially since Zenith realized that these mods were a real
benefit(from a marketing point of view... follow the dollar), so much so they designed the new
750 with these mods plus! Right now I'm waiting to see if Zenith places them on the new 750
wing!!!
Ron
:--)> I will be a total believer when John Gilpin designs, test flys and markets his own
:--)> plane based on slat-less wings. Until then he is a VG salesman who wants to sell
:--)> his product..... Ps... I have installed the Zenith VG's on the horizontal
:--)> stabilizer of my 801 and I admit it made a big difference............ But.... my
:--)> horizontal stabilizer didn't have slats on it to start with so I cannot draw any
:--)> conclusions.... YMMV..
:--)>
:--)> do not archive
:--)>
:--)>
:--)> Ben Haas
:--)> N801BH
:--)> www.haaspowerair.com
:--)>
:--)> --------
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rvickski(at)yahoo.com
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| Posted: Sun May 12, 2013 7:57 pm Post subject: Slats |
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OK, I think I understand the concepts but am open to suggestions.
Removing the slat shortens chord length. The 701 plans calls out the correct C.G. range to be between 20 and 35% mean aerodynamic chord, measured from the slat leading edge at rib #1. I'm thinking that removing the slat will move the CG range rearward slightly.
I do think that JG has demonstrated his VG's but I am interested in the WB calculations.
So, slat-less and using a heavier engine means more rear ballast for me, which I'd rather avoid as much as possible.
John Bolding has provided a nose rib pattern for the 65018 airfoil which should restore the GC range forward. It is very close to the same as the Savannah-S wing. Interestingly, the CG range is 25 to 38% MAC per the Savannah POH.
Since the Ex got the farm, extreme STOL is less important than lessening some drag.
Roy
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johngilpin
Joined: 23 Mar 2011
Posts: 93
Location: 004
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| Posted: Mon May 13, 2013 1:13 am Post subject: Slats |
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Gday Roy,
That's a real good question.......
We tested many times with several aircraft, and couldn't detect any pitch trim change with slats or slats removed. Which would indicate that the slats weren't contributing much, if anything, to lift at cruise. More recent experience of an aircraft with an already hose heavy tendency (early model 701 with fuel tank in the cowl and battery mounted on the firewall) noticed an increased hose heavy feeling with the slats removed.
In 1990 I carried to Sun'nFun, one of the first reduction drives for a Subaru EA81 from a local manufacturer looking for a market over there. When I showed it to Chris and said that the installed weight of the Sub would be about 200lbs, he immediately said, "...too heavy, too heavy..." That was the first year that Zenith had a 912 on the 701, and even with that engine I noticed that they had a lump of lead wired onto the tail skid (this would have been an early model 701 with the fuel tank in the cowl).
Hans' 701 with a Rotax 912s weighs in at max forward 20% (only pilot and min fuel), and fully loaded at 26%, referenced from the leading edge of the wing itself, without slats. It balances very well at all speeds. This is already right at the forward end of the recommended range, so if you are to have an engine that weighs considerably more that the Rotax, it would certainly be too nose heavy.....
You mentioned John Boldings65018nose profile. I think that'd be a good way to go to help that heavy engine. I did calculations long ago and can't find them now, but as I remember, it appeared that extended leading edge would move the center of lift forward about 3%. You might still need to put the battery right in the tail, but hopefully not add extra weight.
This is getting a bit experimental, but not radical, and you seem to be cautious and aware of the issues, so it should be an interesting experiment. I look forward to hearing the results.
JG
| Quote: | From[b][/b]
I would like your considered opinion in regards to using the full 65018 nose rib and leading edge. The CG range being 20-35% in the original configuration, from front edge of slat to rear edge of flaperon. Does or did you notice any aft CG tendencies without the slat? My reason for asking is that my firewall forward weight will exceed 200 poun ds and I do not want to create a compounding situation running slatless. |
[/b]
[quote][b]
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rockiedog2
Joined: 03 Mar 2010
Posts: 19
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| Posted: Mon May 13, 2013 2:40 am Post subject: Slats |
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>>>So, slat-less and using a heavier engine means more rear ballast for me, which
I'd rather avoid as much as possible
Hi Roy
The slats weigh 13# and even tho close to the CG range help move the CG aft when removed.
[quote][b]
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rvickski(at)yahoo.com
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| Posted: Mon May 13, 2013 5:14 am Post subject: Slats |
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Thanks Joe, JG and of course John B.
This project has been sitting on top dead center for too long now, I've been looking at half skinned wings for close to 5 years and your inputs have cleared up some of my confusion.
I'll gain back some of those 13 pounds by upping the leading edge skin to .020, the .016 is pretty fragile. I substituted 2024 material for the wing attach points long ago, that's the only other change on the SP wing.
What I want to end up with is a cruiser version of a 701 since the mission changed and I'm already so far into it. I am leaning toward picking up a set of 750 cruiser plans, the single strut and tail group have appeal.
It's time to cut some forming blocks, maybe.
Roy Szarafinski www.roysgarage.com
roy(at)roysgarage.com (roy(at)roysgarage.com)
rvickski(at)yahoo.com (rvickski(at)yahoo.com)
On May 13, 2013, at 6:40 AM, "Joe Spencer" <jpspencer(at)cableone.net (jpspencer(at)cableone.net)> wrote:
[quote]
Hi Roy
The slats weigh 13# and even tho close to the CG range help move the CG aft when removed.
[b]
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d.shrader
Joined: 21 Nov 2008
Posts: 38
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| Posted: Wed May 22, 2013 1:42 pm Post subject: Re: Slats |
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Same could be said about a guy that touts on about auto conversions, but I prefer not to throw stones but instead respect his effort and keep an open mind
Dave
| n801bh(at)netzero.com wrote: | I will be a total believer when John Gilpin designs, test flys and markets his own plane based on slat-less wings. Until then he is a VG salesman who wants to sell his product..... Ps... I have installed the Zenith VG's on the horizontal stabilizer of my 801 and I admit it made a big difference............ But.... my horizontal stabilizer didn't have slats on it to start with so I cannot draw any conclusions.... YMMV..
do not archive
Ben Haas
N801BH
www.haaspowerair.com
-------- |
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kmccune
Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA
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striplic(at)gmail.com
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| Posted: Sat Jul 13, 2013 5:07 am Post subject: Slats |
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John,
I touched on this question with Caleb (sp? at Zenith) about where to place a fuselage header tank (in addition to the smaller 6 gal wing tanks) in a 701 with a 582 engine. The question was behind the seat or in front of the panel. He stated the airplane would tend to have an aft CG "anyway" so definitely not behind the seat. Obviously, the 582 (with B gearbox and wooden prop - battery can be moved to various places to alter W/B) weighs less than the 912 so that is the logical conclusion. I have yet to weigh/balance my 701, but I can already tell that will be the case. How slats on or off affect center of lift. ???
Cliff
On Jul 13, 2013, at 7:45 AM, kmccune wrote:
| Quote: |
Hi John,
Is the following statement about a 701 with a 912 or a 582? Because I just bought a cowl tank 
"More recent experience of an aircraft with an already hose heavy tendency (early model 701 with fuel tank in the cowl and battery mounted on the firewall) noticed an increased hose heavy feeling with the slats removed. "
--------
Always do what you are afraid to do.
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it"
Dorothy McCune
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=404592#404592
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kmccune
Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA
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| Posted: Sat Jul 13, 2013 11:40 am Post subject: Re: Slats |
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Thanks Cliff,
That was my original thought as well.
Kevin
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_________________
“Always do what you are afraid to do.”
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune |
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jhb478(at)yahoo.com
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| Posted: Sat Jul 13, 2013 11:55 am Post subject: Slats |
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Hi Kevin,
I could tell no difference slats on or off, JG has stated a long time ago that the trim setting didn't change when he removed the slats and added VG's, that tells me all I need to know about center of lift using the bastard airfoil sans slats.
JB
From: kmccune <kmccune(at)somtel.net>
To: zenith701801-list(at)matronics.com
Sent: Saturday, July 13, 2013 7:45 AM
Subject: Re: Slats
--> Zenith701801-List message posted by: "kmccune" <kmccune(at)somtel.net (kmccune(at)somtel.net)>
Hi John,
Is the following statement about a 701 with a 912 or a 582? Because I just bought a cowl tank
"More recent experience of an aircraft with an already hose heavy tendency (early model 701 with fuel tank in the cowl and battery mounted on the firewall) noticed an increased hose heavy feeling with the slats removed. "
--------
“Always do what you are afraid to do.â€
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it"
Dorothy McCune
Read this topic online here:
http://forums.matronics.com/viewtoptp://www.matronics.com/Navigator?Zenith701801-List" target="_blank">http://www.matronics.com/Navigator?Zenith701801-Lista href="http://forums.matronics.com/" target="_blank">http://forums.mat &nbs//www.matronics.com/contribution" target="_blank">http://www.matronics.co==================
[quote][b]
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jhb478(at)yahoo.com
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| Posted: Sat Jul 13, 2013 11:59 am Post subject: Slats |
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John, Have you flown a 701 with and without slats?? Done any testing using real numbers??
Several on this list have done that and all reach the same conclusion.
I DID study up on slats/slots .
JB
From: kmccune <kmccune(at)somtel.net>
To: zenith701801-list(at)matronics.com
Sent: Saturday, July 13, 2013 9:12 AM
Subject: Zenith701801-List: Re: Slats
--> Zenith701801-List message posted by: "kmccune" <kmccune(at)somtel.net (kmccune(at)somtel.net)>
Actually it does not, the slat may be cut out of the front of the original airfoil, but it is extended and I believe rotated slightly to create the slot. If you tape it up, you will have an extended nose shaped differently the the original airfoil.
Kevin
[quote="JohnDRead(at)aol.com"]Filling in the slot with tape just makes the airfoil back to the basic airfoil that has about a 1.3 coefficient of lift. It's the slats that make the difference. I am at a loss to understand why any of the "Slat Removal Group" bothered to build the 701 in the first place. Didn't you know it had slats and what they do?? Slats double the lift of a given airfoil VGs do not they only make a poor performing airfoil work better. Taking the slats off of the 701 wing make a completely different airfoil so you have become test pilots not experimental pilots. The waiver that you signed with Zenith when you undertook the 701 construction could really bite you in the butt in the event of a incident! Have fun. All intelligent replies will be answered. Please read Abbott and Von Doenhoff chapter on slotted airfoils before you start typing. Happy flying.
Regards, John
CH701 - Colorado - Jabiru 3300
Cell: 719-494-4567
Home: 303-648-3261
--------
“Always do what you are afraid to do.â€
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune
Read this topic online here:
http://forums.matronics.coref="http://www.matronics.com/Navigator?Zenith701801-List" target="_blank">http://www.matronics.com/Navigator?Zenith701801-Lista href="http://forums.matronics.com/" target="_blank">http://forums.mat &nbs//www.matronics.com/contribution" target="_blank">http://www.matronics.co==================
[quote][b]
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kmccune
Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA
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| Posted: Sat Jul 13, 2013 12:14 pm Post subject: Re: Slats |
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Hi John,
My question was about the cowl tank and w/b, I just bought one.
Thanks though.
Kevin
[quote="jhb478(at)yahoo.com"]Hi Kevin,
I could tell no difference slats on or off, JG has stated a long time ago that the trim setting didn't change when he removed the slats and added VG's, that tells me all I need to know about center of lift using the bastard airfoil sans slats.
JB
From: kmccune <kmccune>
To: zenith701801-list(at)matronics.com
Sent: Saturday, July 13, 2013 7:45 AM
Subject: Re: Slats
--> Zenith701801-List message posted by: "kmccune" <kmccune>
Hi John,
Is the following statement about a 701 with a 912 or a 582? Because I just bought a cowl tank
"More recent experience of an aircraft with an already hose heavy tendency (early model 701 with fuel tank in the cowl and battery mounted on the firewall) noticed an increased hose heavy feeling with the slats removed. "
--------
“Always do what you are afraid to do.â€
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it"
Dorothy McCune
Read this topic online here:
http://forums.matronics.com/viewtoptp://www.matronics.com/Navigator?Zenith701801-List" target="_blank">http://www.matronics.com/Navigator?Zenith701801-Lista href="http://forums.matronics.com/" target="_blank">http://forums.mat &nbs//www.matronics.com/contribution" target="_blank">http://www.matronics.co==================
| | - The Matronics Zenith701801-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith701801-List |
|
_________________
“Always do what you are afraid to do.”
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune |
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JohnDRead(at)aol.com
Guest
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| Posted: Sat Jul 13, 2013 1:37 pm Post subject: Slats |
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Thank you Robert for a thoughtful and accurate reply.
Regards, John
CH701 - Colorado - Jabiru 3300
Cell: 719-494-4567
Home: 303-648-3261
In a message dated 7/13/2013 3:07:05 P.M. Mountain Daylight Time, robert.eli(at)comcast.net writes:
| Quote: |
All the slats do is to permit the angle of attack to increase beyond the point where stall would normally occur.. The coefficient of lift increases with increasing angle of attack up to the stall point, and it is the same with, or without, slats.... The slats permit the increase to continue beyond what would be possible without slats by delaying the stall to a higher angle of attack.. The slats do not increase the lift coefficient in level flight... And they do not improve the lift coefficient at moderate angles of attack.. The slats allow a greater increase in angle of attack as compared to VG's.. but the effect is the same, which is to delay the stall point to a greater angle of attack.. They both delay the stall point to greater angles of attack than would otherwise be possible.. There is a good plot in this behavior in the zenith document below, with regard to the Zenith slats: PS: The biggest difference between the two is that the VG's have less drag as compared to the slats up to the stall point.
http://www.zenithair.com/stolch801/design/design.html
Robert Eli
CH701
From: "kmccune" <kmccune(at)somtel.net>
To: zenith701801-list(at)matronics.com
Sent: Saturday, July 13, 2013 10:12:46 AM
Subject: Re: Slats
--> Zenith701801-List message posted by: "kmccune" <kmccune(at)somtel.net>
Actually it does not, the slat may be cut out of the front of the original airfoil, but it is extended and I believe rotated slightly to create the slot. If you tape it up, you will have an extended nose shaped differently the the original airfoil.
Kevin
[quote="JohnDRead(at)aol.com"]Filling in the slot with tape just makes the airfoil back to the basic airfoil that has about a 1.3 coefficient of lift. It's the slats that make the difference. I am at a loss to understand why any of the "Slat Removal Group" bothered to build the 701 in the first place. Didn't you know it had slats and what they do?? Slats double the lift of a given airfoil VGs do not they only make a poor performing airfoil work better. Taking the slats off of the 701 wing make a completely different airfoil so you have become test pilots not experimental pilots. The waiver that you signed with Zenith when you undertook the 701 construction could really bite you in the butt in the event of a incident! Have fun. All intelligent replies will be answered. Please read Abbott and Von Doenhoff chapter on slotted airfoils before you start typing. Happy flying.
Regards, John
CH701 - Colorado - Jabiru 3300
Cell: 719-494-4567
Home: 303-648-3261
--------
“Always do what you are afraid to do.�
R.W. Emerson (1803-1882)
"Real freedom is the sustained act of being an individual." WW - 2009
"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=404595#404595
bsp; -================
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