Van's Air Force
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Easy ways to lower RV-4 Stall Speed?
- Thread starter airduct
- Start date
What makes you think VGs will work? Do not believe anyone selling VGs that can not produce data for you model and type airplane. Even then I would not believe.
Oh and the question, why?
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Van's website list 48mph solo and 54mph TOGW stall speed. That is plenty slow.
woodmanrog
Well Known Member
The light sport RV9 in Florida is bing built by Jay Kurtz at the Lakeland South Airport. You may want to give him a call.
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pierre smith
Well Known Member
The RV-7 batwing tips add a little area and probably lower the stall speed a little.
As others have asked....why?
The Lancair guys are already soooo jealous of all the RV's slow stall speeds
Best,
As others have asked....why?
The Lancair guys are already soooo jealous of all the RV's slow stall speeds
Best,
southtarnation
Well Known Member
I'm working with Jay at South Lakeland to restore my -4 and I'm planning to install the Sam James carbon fiber wing tips. I already have them. They are the -7 style and add about 8" to each wing. I think it will lower the stall slightly but Jay has a few other tricks up his sleeves too.
For those asking why one would want to lower the stall especially... What's the max stall speed for Elsa?
For those asking why one would want to lower the stall especially... What's the max stall speed for Elsa?
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scsmith
Well Known Member
fuselage strake
There is a small fuselage strake that has been demonstrated on a couple of RV-8's to help reduce stall speed about 5 kts.
Not sure it would help on the RV-4 though. The RV-8 has a particular issue with the landing gear strut contaminating the wing flow at the root that can cause an elevated stall speed, although a very mushy one. The strake helps clean the flow up in that area.
Do a search on 'strake' and you will find discussion, links, pictures.
One of the reported down-sides is that it removes the nice stall warning that the -8 has.
There is a small fuselage strake that has been demonstrated on a couple of RV-8's to help reduce stall speed about 5 kts.
Not sure it would help on the RV-4 though. The RV-8 has a particular issue with the landing gear strut contaminating the wing flow at the root that can cause an elevated stall speed, although a very mushy one. The strake helps clean the flow up in that area.
Do a search on 'strake' and you will find discussion, links, pictures.
One of the reported down-sides is that it removes the nice stall warning that the -8 has.
I changed to the "batwing" tips on my -6 and saw absolutely NO change to stall speeds.
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humptybump
Well Known Member
I have the strakes on my RV-8 and can report the airplane hase a very very subtle stall/break. However, at 1500 lbs solo, I stall right at 50kts so I would not say the strakes dramatically lower the stall speed.
smokyray
Well Known Member
How slow can you go?
W2,
My first question is WHY? The stock RV4 wing and tips provide one of the best slow fight dog-fighting, aerobatic and STOL combination sport civilian airplanes I have ever flown. You can whip nearly any adversary with equal or greater HP in a 1 V 1 or slow turning fight, perform sportsman aerobatics and go land on a short strip alongside a Super Cub. So, how short would you like to land? 500' strips? 300'? How slow would you like to fly 25, 30 knots? Realistic goals yield realistic results.
Over the first 10 years flying my RV4, several of my RV4 and Rocket friends installed VG's. The VG's for the RV4 were initially designed by a Boeing Engineer for Larry Vetterman. Larry has extensive Super Cub VG experience and wanted to apply the technology to his RV4. They work as advertised and lower stall speed an honest 5 knots. They also make the actual stall a non-event. However, the stock wing stalls very straightforward IMHO. I have seen the RV6 "long wing-tips" designed by Paul Lipps on the RV6 which help at higher altitudes but don't lower stall speed appreciably. Remember, the wing was stressed and designed to provide lift at a specific load and span range. Deviating from that treads into the test pilot/engineer arena, which is cool, just make sure you know what you're doing.
My advice is to go out and practice slow flight solo at a safe altitude to perfection, with and without flaps with your stock RV4 wing and tips. Roll into 30 degree bank turns, put the trim full aft and add power to hold altitude. Feeling confident? Try beginning a loop at 100 knots. How about a "dirty" roll at 80? Realistically assess your strengths and weaknesses and see if maybe your own pilotage can help your capability to fly at or nearer stall speed. The better you get at slow flight, the better every aspect of flying the airplane will get.
When adversity strikes and you need to fly very slow, it will be a non-event.
V/R
Smokey
Dues gladly paid in Iraq...
Gladly paid to DR anyway...
PS:My initial test flight on my RV4 in 1996 was from my friends 800' one-way strip in NW FL. You can bet I was interested in how safely slow I could fly final and "shoehorn my 4" back in there. I practiced slow flight at altitude and since my test flight was my first RV flight, I explored the envelope. I found I could fly with finesse with full flaps at 53 KIAS. I also found that with finesse I could safely fly final at 60 KIAS with stock wings, tips and flap settings. (BTW, RV4 flaps at full only reduce stall speed 5 knots). I ended up making sixteen takeoffs and landings that day in my RV4 from "Porter INTL".
Still want to stall slower? Build one of these: http://www.eaa.org/news/2011/2011-05-12_stol.asp
W2,
My first question is WHY? The stock RV4 wing and tips provide one of the best slow fight dog-fighting, aerobatic and STOL combination sport civilian airplanes I have ever flown. You can whip nearly any adversary with equal or greater HP in a 1 V 1 or slow turning fight, perform sportsman aerobatics and go land on a short strip alongside a Super Cub. So, how short would you like to land? 500' strips? 300'? How slow would you like to fly 25, 30 knots? Realistic goals yield realistic results.
Over the first 10 years flying my RV4, several of my RV4 and Rocket friends installed VG's. The VG's for the RV4 were initially designed by a Boeing Engineer for Larry Vetterman. Larry has extensive Super Cub VG experience and wanted to apply the technology to his RV4. They work as advertised and lower stall speed an honest 5 knots. They also make the actual stall a non-event. However, the stock wing stalls very straightforward IMHO. I have seen the RV6 "long wing-tips" designed by Paul Lipps on the RV6 which help at higher altitudes but don't lower stall speed appreciably. Remember, the wing was stressed and designed to provide lift at a specific load and span range. Deviating from that treads into the test pilot/engineer arena, which is cool, just make sure you know what you're doing.
My advice is to go out and practice slow flight solo at a safe altitude to perfection, with and without flaps with your stock RV4 wing and tips. Roll into 30 degree bank turns, put the trim full aft and add power to hold altitude. Feeling confident? Try beginning a loop at 100 knots. How about a "dirty" roll at 80? Realistically assess your strengths and weaknesses and see if maybe your own pilotage can help your capability to fly at or nearer stall speed. The better you get at slow flight, the better every aspect of flying the airplane will get.
When adversity strikes and you need to fly very slow, it will be a non-event.
V/R
Smokey
Dues gladly paid in Iraq...
Gladly paid to DR anyway...
PS:My initial test flight on my RV4 in 1996 was from my friends 800' one-way strip in NW FL. You can bet I was interested in how safely slow I could fly final and "shoehorn my 4" back in there. I practiced slow flight at altitude and since my test flight was my first RV flight, I explored the envelope. I found I could fly with finesse with full flaps at 53 KIAS. I also found that with finesse I could safely fly final at 60 KIAS with stock wings, tips and flap settings. (BTW, RV4 flaps at full only reduce stall speed 5 knots). I ended up making sixteen takeoffs and landings that day in my RV4 from "Porter INTL".
Still want to stall slower? Build one of these: http://www.eaa.org/news/2011/2011-05-12_stol.asp
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smokyray
Well Known Member
Tight Squeeze?
Want a slower landing speed? Practice a slower speed, first at altitude, then on a longer strip. Once you're confident, practice approaches at your home strip before committing. After several thousand RV4 landings, I can assure you it's possible. After 20 years of RV4 flying it still lands slower than most stock civilian light planes, except true bush planes like the Maule, Cessna 180/185 Super Cub and Scout. It also outruns them hands down on less HP.
My current strip is 1500' usable with trees at both ends. Flying final at 60 KIAS works well but you have to be disciplined to hold pitch attitude (AOA) to touchdown. A C/S prop does help, to a point. Don't be tempted to drop the nose once you clear the obstacle. Hold A/S Pitch/power to touchdown.
Practice makes perfect.
Smokey
PS: Larry Vetterman's VG article: http://www.vansairforce.net/vetterman/vg.htm
W2,
Want a slower landing speed? Practice a slower speed, first at altitude, then on a longer strip. Once you're confident, practice approaches at your home strip before committing. After several thousand RV4 landings, I can assure you it's possible. After 20 years of RV4 flying it still lands slower than most stock civilian light planes, except true bush planes like the Maule, Cessna 180/185 Super Cub and Scout. It also outruns them hands down on less HP.
My current strip is 1500' usable with trees at both ends. Flying final at 60 KIAS works well but you have to be disciplined to hold pitch attitude (AOA) to touchdown. A C/S prop does help, to a point. Don't be tempted to drop the nose once you clear the obstacle. Hold A/S Pitch/power to touchdown.
Practice makes perfect.
Smokey
PS: Larry Vetterman's VG article: http://www.vansairforce.net/vetterman/vg.htm
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Andrew M
Well Known Member
Drooped ailerons
The original RV-3 had a little cam arrangement and lever in the bottom of the stick where the aileron tubes hook up. Moving the lever moved both ailerons down A photo from Sport Aviation 1972 shows it, kind of. Van used this to help him operate off the "farm strip"
The original RV-3 had a little cam arrangement and lever in the bottom of the stick where the aileron tubes hook up. Moving the lever moved both ailerons down A photo from Sport Aviation 1972 shows it, kind of. Van used this to help him operate off the "farm strip"
The first part is true (the airplane had drooping ailerons).
The second part is false... The drooping ailerons had no effect what so ever (that is why they were not part of the RV-3 design/plans for other builders.
Andrew M
Well Known Member
Sport aviation quote
22 Oct 1972. Sport Aviation write up titled The amazing RV-3 by Jack Cox ...."By flipping this over 180 degrees, (the lever at the bottom of the stick) the ailerons droop 18 degrees. The first notch of flaps equals this, creating a high lift wing" "Power off, clean, and in level flight attitude, the aircraft pays off at 54 mph indicated; with the flaps a 48 mph, and with flaps and ailerons drooped at 45."
22 Oct 1972. Sport Aviation write up titled The amazing RV-3 by Jack Cox ...."By flipping this over 180 degrees, (the lever at the bottom of the stick) the ailerons droop 18 degrees. The first notch of flaps equals this, creating a high lift wing" "Power off, clean, and in level flight attitude, the aircraft pays off at 54 mph indicated; with the flaps a 48 mph, and with flaps and ailerons drooped at 45."
Ok, You win.
I was just repeating what Van told me in person while we were restoring the airplane for donation to the EAA museum, but if Jack Cox wrote it, it must be true.
N941WR
Legacy Member
Then build a -9. It just cracks me up every time I come into land and realize how truly slow I can make an approach and that my VSI is showing me descending at around 400 to 600 FPM. The slower I go, the faster I come down.
Why........
The Super Cub stalls a lot slower than an RV-4, yet people have been working to get it to stall slower, basically for as long as the Super Cub has been around. Bigger flaps, extended wings, cuffs, drooping ailerons, VG's, different tips, slats and slots. You name it, it's been tried. On the basis of this statement all these people are wasting their time.
Why do they do it? To improve the capability of their aeroplane. It would be great if we can hear from people who have done some work done to improve the RV-4 and RV-6's capability in the same manner. Apart from it being enormously interesting, it might just help some of us out.
Andrew.
The Super Cub stalls a lot slower than an RV-4, yet people have been working to get it to stall slower, basically for as long as the Super Cub has been around. Bigger flaps, extended wings, cuffs, drooping ailerons, VG's, different tips, slats and slots. You name it, it's been tried. On the basis of this statement all these people are wasting their time.
Why do they do it? To improve the capability of their aeroplane. It would be great if we can hear from people who have done some work done to improve the RV-4 and RV-6's capability in the same manner. Apart from it being enormously interesting, it might just help some of us out.
Andrew.
Kahuna
Moderatoring
A recent AOPA Video with the RV-4 and VG's
Mark Albery
Well Known Member
First thing I would check is your static system. I bought an RV-4 a few years ago and it seemed to have a high stall speed. It came down about 6 mph when I unblocked the paint inside the static ports and fixed the leaks in the system.
There is no reason that RV-4s at the same weight should vary much in stall speed. If the wings and tailplane are rigged correctly there should be little variation from book values.
Another check is to fly 1 or 2 mph above the indicated stall speed (at a safe altitude) and check the GPS speed while flying up and down wind. Correct them for density and see how they compare with the ASI.
There is no reason that RV-4s at the same weight should vary much in stall speed. If the wings and tailplane are rigged correctly there should be little variation from book values.
Another check is to fly 1 or 2 mph above the indicated stall speed (at a safe altitude) and check the GPS speed while flying up and down wind. Correct them for density and see how they compare with the ASI.
smokyray
Well Known Member
How slow can you go...
Hi Andrew,
Couldn't agree more. I would estimate that less than 10% of the current RV community operate their airplanes from unimproved airstrips less than 1500' long on a regular basis or fully explore the slow flight envelope. I have heard some mention they have never even stalled their RV. I respond with "Well then how did you land?"
There are still things that could be done to lower approach speed of the RV4 in addition to VG's. I modified my 4's flaps back in the day. I added a reflex up position similar to the Maule and 5 more degrees down. Neither yielded any appreciable improvement. The best RV4 improvement is the lack of technology! Less weight, manual flaps. Why? I use the Super Cub technique on STOL takeoffs by performing a rolling takeoff on soft ground followed immediately by application of full flaps. Once airborne I slowly raise them while accelerating to best climb speed. This technique has served me well over the years significantly reducing takeoff distances on soft strips or rough ground. (I also use my manual flaps in 1 V 1's as they improve turn radius below 100 knots.) VG's are a distinct improvement, but not a huge amount IMHO, having flown several RV4's with them.
I still think a stock, lightweight RV4 performs exceptionally well in comparison to anything else in it's category.
It is what it is...
V/R
Smokey
www.fly-4-life.com
My RV4 at U72
PS: I purchased my RV4 tail kit in 1989' simply because I saw a magazine article labeled "total performance" and wanted a 180 MPH Super Cub. The RV4 doesn't quite measure up at the low end but is a wonderful compromise in all other areas. The birthplace of my RV4 was alongside my late friend Arvil Porter's 800' one-way sloped STOL strip. My initial test flight from The USS Porter would set the tone for the rest of it's RV life, total performance...Here's a nice slow approach for you: http://www.youtube.com/watch?v=6XYFcw1c-Oo
Hi Andrew,
Couldn't agree more. I would estimate that less than 10% of the current RV community operate their airplanes from unimproved airstrips less than 1500' long on a regular basis or fully explore the slow flight envelope. I have heard some mention they have never even stalled their RV. I respond with "Well then how did you land?"
There are still things that could be done to lower approach speed of the RV4 in addition to VG's. I modified my 4's flaps back in the day. I added a reflex up position similar to the Maule and 5 more degrees down. Neither yielded any appreciable improvement. The best RV4 improvement is the lack of technology! Less weight, manual flaps. Why? I use the Super Cub technique on STOL takeoffs by performing a rolling takeoff on soft ground followed immediately by application of full flaps. Once airborne I slowly raise them while accelerating to best climb speed. This technique has served me well over the years significantly reducing takeoff distances on soft strips or rough ground. (I also use my manual flaps in 1 V 1's as they improve turn radius below 100 knots.) VG's are a distinct improvement, but not a huge amount IMHO, having flown several RV4's with them.
I still think a stock, lightweight RV4 performs exceptionally well in comparison to anything else in it's category.
It is what it is...
V/R
Smokey
www.fly-4-life.com
My RV4 at U72
PS: I purchased my RV4 tail kit in 1989' simply because I saw a magazine article labeled "total performance" and wanted a 180 MPH Super Cub. The RV4 doesn't quite measure up at the low end but is a wonderful compromise in all other areas. The birthplace of my RV4 was alongside my late friend Arvil Porter's 800' one-way sloped STOL strip. My initial test flight from The USS Porter would set the tone for the rest of it's RV life, total performance...Here's a nice slow approach for you: http://www.youtube.com/watch?v=6XYFcw1c-Oo
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G.ICON
Steve Sampson operates his RV 4 out of a 1020ft grass strip with 50 ft trees on the end of RW 31. If you search G.ICON on google he has several videos of take off and landings at his strip.
I intend to use a similar length strip. It seems to me you can spend a lot of time fitting things like VG's, which may be better spent practicing flying techniques.
Remember, there is no such thing as a free lunch, VG's will reduce cruise speed. The thing that attracted me to the RV4...... RV's in general is probably the same thing that attracted most owners....... the very wide flight envelope...... something around 4 to 1 stall to max speed.
Now if you can show me a way to reduce the stall without decreasing the cruise I would be interested!!
Steve Sampson operates his RV 4 out of a 1020ft grass strip with 50 ft trees on the end of RW 31. If you search G.ICON on google he has several videos of take off and landings at his strip.
I intend to use a similar length strip. It seems to me you can spend a lot of time fitting things like VG's, which may be better spent practicing flying techniques.
Remember, there is no such thing as a free lunch, VG's will reduce cruise speed. The thing that attracted me to the RV4...... RV's in general is probably the same thing that attracted most owners....... the very wide flight envelope...... something around 4 to 1 stall to max speed.
Now if you can show me a way to reduce the stall without decreasing the cruise I would be interested!!
smokyray
Well Known Member
Cuff him...
Couldn't agree more. SS and I discussed this subject several times during his construction of G-IKON. My point has always been the stock RV4 does fine just like it is, mine being as stock as they come. In the 1500 hours I flew my RV4, I calculated that 30% of all my landings were on less than 1200' long, unimproved runways. Personally, I don't like the way VG's look, they tend to clutter the RV wing. As far as mods that decreases stall speed without subsequent cruise speed loss, there is one I have seen that works, at least on the Cessna 180.
A friend installed this STOL kit on his C-180 in AK and I flew it before and after. Not one knot of speed was sacrificed yet stall became a non-event. A leading edge Cuff is standard on nearly every Missionary Aviation aircraft and have proven themselves over time. http://www.steneaviation.com/sportsman_stol_about.asp?menuID=7~7
Food for thought...
V/R
Smokey
Dues gladly paid in Iraq...
Gladly paid to DR anyway...
Steve,
Couldn't agree more. SS and I discussed this subject several times during his construction of G-IKON. My point has always been the stock RV4 does fine just like it is, mine being as stock as they come. In the 1500 hours I flew my RV4, I calculated that 30% of all my landings were on less than 1200' long, unimproved runways. Personally, I don't like the way VG's look, they tend to clutter the RV wing. As far as mods that decreases stall speed without subsequent cruise speed loss, there is one I have seen that works, at least on the Cessna 180.
A friend installed this STOL kit on his C-180 in AK and I flew it before and after. Not one knot of speed was sacrificed yet stall became a non-event. A leading edge Cuff is standard on nearly every Missionary Aviation aircraft and have proven themselves over time. http://www.steneaviation.com/sportsman_stol_about.asp?menuID=7~7
Food for thought...
V/R
Smokey
Dues gladly paid in Iraq...
Gladly paid to DR anyway...
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usmcshooter
Member
Stene Rocks
Stevie Ray,
You just hit on one of the only great STOL kits out there! Way better than Horton or Bush. I am ordering my Stene for the Cessna in a couple of months. Dave Stoots who owns Stoots Aviation in Alaska swears by them. Ten minutes talking to Dave and you will appreciate anything he endorses. It changes the chord line and actually increases top speed by a few knots. There are three Stene modified planes at our airport (L22) and they are all believers. Since I have been doing more and more animal rescue flights (I get those dirty little short strips and dry lake bed landings here) I have looked around and am going with the best.....Stene. That being said, the Cessna doesn't have an envelope anywhere near the RV4. I watch locals get in and out of 500ft dirt strips with nothing other than pilot technique and simple design (barebones fixed pitch props and 160hp engines). Save the weight, save the money, spend it on fuel and fun.
Stevie Ray,
You just hit on one of the only great STOL kits out there! Way better than Horton or Bush. I am ordering my Stene for the Cessna in a couple of months. Dave Stoots who owns Stoots Aviation in Alaska swears by them. Ten minutes talking to Dave and you will appreciate anything he endorses. It changes the chord line and actually increases top speed by a few knots. There are three Stene modified planes at our airport (L22) and they are all believers. Since I have been doing more and more animal rescue flights (I get those dirty little short strips and dry lake bed landings here) I have looked around and am going with the best.....Stene. That being said, the Cessna doesn't have an envelope anywhere near the RV4. I watch locals get in and out of 500ft dirt strips with nothing other than pilot technique and simple design (barebones fixed pitch props and 160hp engines). Save the weight, save the money, spend it on fuel and fun.
N42AH
Well Known Member
Micro Aerodynamics VG's
There is info on their VG's
http://www.microaero.com/CS_PDF/KitPlanes/RV_CS.pdf
There is info on their VG's
http://www.microaero.com/CS_PDF/KitPlanes/RV_CS.pdf
One way to play with VGs is to build your own.
http://www.hallwindmeter.com/vortex.php
You can make them from .025 aluminum and stick them on your plane with double sticky tape.
These things are so simple to cut bend & trim that it only takes a few minutes per each.
You don't need a whole wing full, just one or two on each wing makes the difference.
I installed 2 ea on my Thorp T-18, 12" back from the leading edge, the inboard VG 2" outboard of the inner end of the aileron, the second VG is 12" further out the wing.
These 2 enhanced the aileron effectiveness into the deepest of stalls.
If you don't care for the result of your effort, take them off and re-wax your wing.
I am finishing my RV-8, and might try them on the fuselage above the leading edge of the wing instead of that little strake some people install to effect flow disturbed by the landing gear.
http://www.hallwindmeter.com/vortex.php
You can make them from .025 aluminum and stick them on your plane with double sticky tape.
These things are so simple to cut bend & trim that it only takes a few minutes per each.
You don't need a whole wing full, just one or two on each wing makes the difference.
I installed 2 ea on my Thorp T-18, 12" back from the leading edge, the inboard VG 2" outboard of the inner end of the aileron, the second VG is 12" further out the wing.
These 2 enhanced the aileron effectiveness into the deepest of stalls.
If you don't care for the result of your effort, take them off and re-wax your wing.
I am finishing my RV-8, and might try them on the fuselage above the leading edge of the wing instead of that little strake some people install to effect flow disturbed by the landing gear.
To land where?
As I understand your concern, stall speed implies landing distance (or force to be dissipated, assuming obstacles). Is this "slower is shorter/less force" or do you have a distance in mind? I watch RVs land all the time way too hot....and also watched 5 RVs land simultaneously at Woodland, not a long strip. I feel comfortable on 1500 feet in a fixed pitch 4. I used to hanger with an Eze pilot who thought 3000 was minimum.
This reminds me of when I was building in the early 80s. A builder-engineer came in, looked everything over, and announced, "Well, looks good, but I am going to make the entire D section wet so I can fly from Cali to Oshkosh, non stop" Really? WTF? 1300 hours on, I still think: WTF? Who wants to sit in an RV for 10 hours and pee in a straw? So, how slow do you need to go? My plane flies plenty slow, don't need or want slower. My guess is your needs are best served by being able to maximize your plane's potential to fly awfully **** slow, safely, and to fit into some really small spaces if you choose or need to. MTCents J
As I understand your concern, stall speed implies landing distance (or force to be dissipated, assuming obstacles). Is this "slower is shorter/less force" or do you have a distance in mind? I watch RVs land all the time way too hot....and also watched 5 RVs land simultaneously at Woodland, not a long strip. I feel comfortable on 1500 feet in a fixed pitch 4. I used to hanger with an Eze pilot who thought 3000 was minimum.
This reminds me of when I was building in the early 80s. A builder-engineer came in, looked everything over, and announced, "Well, looks good, but I am going to make the entire D section wet so I can fly from Cali to Oshkosh, non stop" Really? WTF? 1300 hours on, I still think: WTF? Who wants to sit in an RV for 10 hours and pee in a straw? So, how slow do you need to go? My plane flies plenty slow, don't need or want slower. My guess is your needs are best served by being able to maximize your plane's potential to fly awfully **** slow, safely, and to fit into some really small spaces if you choose or need to. MTCents J
Andy Hill
Well Known Member
Scanning the above posts, some aerodynamic aspects might be worth considering
Stall Speed has a number of presentations to a pilot, namely are we talking the true "stall", or when the first warning signs appear (e.g. buffet)? Are we really trying to lower the stall speed (unlikely), or lower approach speed (more likely). Even the TPs see the need to establish for what purpose you are looking at this, and the various definitions 3.3.2
We can add "devices" to our wings to increase the stall AoA - airliners use slats, but there are the RV-8 "cuffs". I am dubious about these, and suspect what they do is remove the buffet warning of the stall due, as stated above, by the gear/wing intersection. They also pretty directly affect the inboard flow above the wing, which at high AoA goes right over the static port and that creates it's own questions.
In the UK, all RVs need an artifical stall warning system except the RV-8, where the above buffet is seen as a benefit.
In a nose dragger, delaying the stall to a higher AoA e.g. VGs will just result in landing on the rudder. In the tail dragger variants do you really want to be getting min landing run by landing tailwheel first and then dropping the mains on?
Aileron droop is used on a few types, and as above, once on the RV-3. Bear in mind flap / aileron droop increase effective Incidence of the wing and such stall will occur at a lower AoA. With Flaps (only) this has the benefit that as you do stall it, at least wing drop is minimised since the root will stall first. Aileron droop risks stalling further out, with a dramatic wing drop at just the altitude you do not want it - and bear in mind you could be nicely set up, just off the stall, and it is you that triggers the stall by use of aileron And given how often we all forget to raise the flaps, think of the issues of Aileron Droop flaps up
Clearly you can reduce the approach speed by just flying closer to the stall - but at increased risk, balanced against field length considerations. As others have said, pilot technique is probably way more important than mods.
Stall Speed has a number of presentations to a pilot, namely are we talking the true "stall", or when the first warning signs appear (e.g. buffet)? Are we really trying to lower the stall speed (unlikely), or lower approach speed (more likely). Even the TPs see the need to establish for what purpose you are looking at this, and the various definitions 3.3.2
We can add "devices" to our wings to increase the stall AoA - airliners use slats, but there are the RV-8 "cuffs". I am dubious about these, and suspect what they do is remove the buffet warning of the stall due, as stated above, by the gear/wing intersection. They also pretty directly affect the inboard flow above the wing, which at high AoA goes right over the static port and that creates it's own questions.
In the UK, all RVs need an artifical stall warning system except the RV-8, where the above buffet is seen as a benefit.
In a nose dragger, delaying the stall to a higher AoA e.g. VGs will just result in landing on the rudder. In the tail dragger variants do you really want to be getting min landing run by landing tailwheel first and then dropping the mains on?
Aileron droop is used on a few types, and as above, once on the RV-3. Bear in mind flap / aileron droop increase effective Incidence of the wing and such stall will occur at a lower AoA. With Flaps (only) this has the benefit that as you do stall it, at least wing drop is minimised since the root will stall first. Aileron droop risks stalling further out, with a dramatic wing drop at just the altitude you do not want it - and bear in mind you could be nicely set up, just off the stall, and it is you that triggers the stall by use of aileron
And given how often we all forget to raise the flaps, think of the issues of Aileron Droop flaps up Clearly you can reduce the approach speed by just flying closer to the stall - but at increased risk, balanced against field length considerations. As others have said, pilot technique is probably way more important than mods.
usmcshooter
Member
agreement
The RV4 is already an outstanding platform. It does everything pretty darn well. That being said, Airduct, I noticed that you shotgunned a bunch of questions, many are about plans deviation, do you actually have a 4 and are building or just trying to decide? I also notice you generally don't respond to threads you started once they have begun. There is a wealth of knowledge here, take their advice, I know I have. Pretty much sticking to the plans all the way with the exception of RV6 tanks, thanks for that one guys.
The RV4 is already an outstanding platform. It does everything pretty darn well. That being said, Airduct, I noticed that you shotgunned a bunch of questions, many are about plans deviation, do you actually have a 4 and are building or just trying to decide? I also notice you generally don't respond to threads you started once they have begun. There is a wealth of knowledge here, take their advice, I know I have. Pretty much sticking to the plans all the way with the exception of RV6 tanks, thanks for that one guys.
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