I have been thinking about the leading edge cuff lately. I have heard that the cuff works almost as good as the slot and I have also heard that the cuff lowers the stall deck angle. The way I understand it, the slot, and slat postpone the stall witch allows you to fly slower but at the cost of a higher deck angle (AOA). This seems to contradict the theory that the cuff lowers the stall deck angle. Perhaps Jerry can jump in and add some more insight. If the cuff lowers the deck angle at stall and lowers the stall speed, I think this would be a great modification. If it lowers the stall speed by postponing the stall to a higher deck angle (AOA), I have less interest in it. Visibility over the nose is critical when landing in tight confined areas. Just hoping that we can all come to the same conclusion on how the cuff works. All the technical papers I have read basically say the cuff softens the stall and makes spin recovery easier. I don't claim to have read every NACA technical paper on this subject. I hope Jerry will step in and clarify this for me
Leading Edge Cuff
- Thread starter ksecub
- Start date
Big AK
Registered User
BIG Alaska
I don't have a cuff....just stock wings with VG's.
A friend who has the cuff on an extended wing with long flaps and ailerons said not to bother with the cuff.
Sorry, no science here for you. Just a second-hand opinion.
The guy with the cuff is a pro. The a/c is used for 135 work. He says he wants the long wing with long flap and aileron. He's built the long wing with flap and aileron for another 135 operator friend of his. The guy had them for awhile and then dinged up his airplane, then removed them and installed some stock wings just to get back in the air. The guy sang the blues for a few years til my friend had time to build another set of long wings so the guy could shuck the stockers.
I just wanted to point out that there are some pros out there that LOVE the long wing with long flap and aileron out to the tips. Many on this site will argue for the stock wing ONLY. Truly everyone must choose his own design compromises for HIS mission only.....and not push his opinion and mission on the rest of us.
Everyone respects Jerry Burr's opinion. Note that for his mission, an extended wing is his preference.
DAVE
A friend who has the cuff on an extended wing with long flaps and ailerons said not to bother with the cuff.
Sorry, no science here for you. Just a second-hand opinion.
The guy with the cuff is a pro. The a/c is used for 135 work. He says he wants the long wing with long flap and aileron. He's built the long wing with flap and aileron for another 135 operator friend of his. The guy had them for awhile and then dinged up his airplane, then removed them and installed some stock wings just to get back in the air. The guy sang the blues for a few years til my friend had time to build another set of long wings so the guy could shuck the stockers.
I just wanted to point out that there are some pros out there that LOVE the long wing with long flap and aileron out to the tips. Many on this site will argue for the stock wing ONLY. Truly everyone must choose his own design compromises for HIS mission only.....and not push his opinion and mission on the rest of us.
Everyone respects Jerry Burr's opinion. Note that for his mission, an extended wing is his preference.
DAVE
About 14 years ago a friend and I purchased Ken Bunch's old cub... N7077D... was a great airplane... had 29" goodyears, borer prop, 160 H.P. and that silly leading edge kit.... It was awsome for getting off... but terrible for trying to get "slow" and keep it stable...It wasn't very predictable... especially in gusty conditions.... than once you touched down.... if it was rough... It would have a tendency to fly off the bumps... it loved that high angle of attack... Problem is... I didn't.... My current cub has stock wings with a set of Micos scheduled to be installed in March.... I have found the stock wing to be much more predictable and would never consider buying a cub with a cuff again......
fobjob
MEMBER
Salt Lake City, Utah
Except that they don't fold for road towing..or easy hanger storage...
And the 2.5 degree twist in the wings to prevent tip stalling reduces speed and climb...
and the ailerons aren't effective....
and the flaps are too small.....
but the curved tips look cool.... :-?
And the 2.5 degree twist in the wings to prevent tip stalling reduces speed and climb...
and the ailerons aren't effective....
and the flaps are too small.....
but the curved tips look cool.... :-?
Wayne Mackey
Registered User
Miles City Montana 406 232 1370
Lunch
Hi Kase I'll contact you and visit on the way home. Jerry.
Hi Kase I'll contact you and visit on the way home. Jerry.
Steve Pierce
BENEFACTOR
Graham, TX
Crash, What extended wing set-up did you have?
Crash
GONE WEST
Nikiski Alaska
I don't anymore. You might be confused with extended leading edges on one of my planes. This is to keep the fabric from scalloping. Smith puts the same thing on all of their Cubs and about half of the Cubs up here have it.
I usually slam any wing mods to get Wayne or Jerry back to the site. It works everytime. Crash
I usually slam any wing mods to get Wayne or Jerry back to the site. It works everytime. Crash
Steve Pierce
BENEFACTOR
Graham, TX
What extended wing mod did you have before your rebuild?
Wayne Mackey
Registered User
Miles City Montana 406 232 1370
cuff
Hi Doug. I can't send you a pict untill saturday. But they only go half way up to the spar from the old leading edge. Jerry.
Hi Doug. I can't send you a pict untill saturday. But they only go half way up to the spar from the old leading edge. Jerry.
Crash
GONE WEST
Nikiski Alaska
Steve Pierce said:
Flaps extended 4" into the fuselage. A third hinge for each flap and flaps extended 14" out toward the wing tip. A fourth hinge for each aileron. Ailerons moved out and extended out to the very end of the extended wings. Drooped tips like Cub Crafters puts on.
The plane was OK in most conditions but was a hand full in a stiff crosswinds. I like a stock wing for "all around" flying conditions and parts availibility. When its all said and done, I can take, and do take my stock wing Cub anyhere I took it when it had modified wings. All the mods in the world will not make up for a crappy pilot. Crash
Crash
GONE WEST
Nikiski Alaska
tempdoug said:
When the FAA allowed it we used to cut .020 2024 T3 at 14", brake a 5/8" 90 on the rear edge for a stiffner and over lap the normal leading edge by 1/2". Notch out for the ribs, PK screw it down to the rib caps and Marston rivet the front edge to the normal leading edge. Use full wrap leading edges all the way to the wing tip bow fairing. Did it in three sections per wing so you had some adjustment in the sheets for wash out. Crash
jerry, i dont know if im understanding you right. would that be half way back to the rear spar from the old leading edge on top of the front spar? im working on a experimental set of wings now and ive always heard about this done, not that im going to do it, just would like to see. ddoug
For those of you interested in the technical stuff, here is an interesting read. At least I thought so.
http://naca.larc.nasa.gov/reports/1950/naca-tn-2228/naca-tn-2228.pdf
I know this study was not done using the USA 35B airfoil, but I think the results might have some relevance to the Cub wing with a cuff (Modification #5).
What do you think?
http://naca.larc.nasa.gov/reports/1950/naca-tn-2228/naca-tn-2228.pdf
I know this study was not done using the USA 35B airfoil, but I think the results might have some relevance to the Cub wing with a cuff (Modification #5).
What do you think?
Fortysix12
Registered User
RanchAero Grand Vista, Brooksville
Nevermind.
Jerry Burr
MEMBER
Sedro Woolley, Washington.
TN2228
Hi Kse. I have always used Mod 5 for my comparasons. Is that what you came up with? Jerry.
Hi Kse. I have always used Mod 5 for my comparasons. Is that what you came up with? Jerry.
Cubus Maximus
Registered User
Jerry Burr
MEMBER
Sedro Woolley, Washington.
Info.
Hi Kse. I didn't have time to look them up earlier, but here is some additional reference material that may interest you.
NACA TN #571. Ordinary and split flaps.
NACA TN #1386. Drooped ailerons.
NASA TP #1589. Leading edge mods.
NACA TN #427. Slots / flaps.
NACA TN #690. Slats / flaps.
Good stuff.
Jerry.
Hi Kse. I didn't have time to look them up earlier, but here is some additional reference material that may interest you.
NACA TN #571. Ordinary and split flaps.
NACA TN #1386. Drooped ailerons.
NASA TP #1589. Leading edge mods.
NACA TN #427. Slots / flaps.
NACA TN #690. Slats / flaps.
Good stuff.
Jerry.I just reread TN# 2228 and realized something profound (at least to me). There is a graph (CLmax vs. AOA) showing the same airfoil (not USA35B) with different leading edge modifications. Modification #5 which most resembles the cub cuff does have a higher CLmax at a higher AOA. The profound thing to me is that the modified leading edge had a lower CL at the lower AOA that the plain airfoil stalled at. From what I can tell, and I am making assumptions here, if you don't increase the AOA and fly at the same AOA as the stock airfoil you will have a reduced CL! It appears that if you don't fly at the higher AOA with the cuff you will not be able to fly as slow. I have a hard time believing this, but that is what the graph suggests.
>>"The profound thing to me is that.......... It appears that if you don't fly at the higher AOA with the cuff you will not be able to fly as slow. I have a hard time believing this, but that is what the graph suggests".<<
The referenced airfoil was a 63(1)-012. Which means that it was an uncambered, 12% thick, symmetrical, 6-series, laminar flow airfoil with a design lift coefficient of 0.3 and a drag bucket that extends a width of 0.1 CL on either side of the design lift coefficient. On that airfoil, the illustrated mods leave the lift slope unchanged and just increase the stall aoa, so you use the higher aoa at stall to allow you to stall slower at a higher aoa. If you want to get the lower stall speed at the original aoa, you just camber the airfoil to make the zero lift aoa negative by the amount needed. But the 2228 data really isn't intended to extrapolate well to our cambered US35Bmod airfoils.
I've often wondered why some of us who mess about with experimental wings haven't built a truly high lift airfoil based on a thickened version of the Selig S1223 or S1223rtl (the thickening would be to allow a stronger rear spar without increasing the spar weight too much). An example of the difference is that the referenced 6-series wing had a 2-D CLmax of about 1.37 roughly. The mods got that up to about 1.6 to 1.7. A stock S1223 can manage about 2.1 or 2.2, more if flapped or with gurney's.
All the best,
JimC
The referenced airfoil was a 63(1)-012. Which means that it was an uncambered, 12% thick, symmetrical, 6-series, laminar flow airfoil with a design lift coefficient of 0.3 and a drag bucket that extends a width of 0.1 CL on either side of the design lift coefficient. On that airfoil, the illustrated mods leave the lift slope unchanged and just increase the stall aoa, so you use the higher aoa at stall to allow you to stall slower at a higher aoa. If you want to get the lower stall speed at the original aoa, you just camber the airfoil to make the zero lift aoa negative by the amount needed. But the 2228 data really isn't intended to extrapolate well to our cambered US35Bmod airfoils.
I've often wondered why some of us who mess about with experimental wings haven't built a truly high lift airfoil based on a thickened version of the Selig S1223 or S1223rtl (the thickening would be to allow a stronger rear spar without increasing the spar weight too much). An example of the difference is that the referenced 6-series wing had a 2-D CLmax of about 1.37 roughly. The mods got that up to about 1.6 to 1.7. A stock S1223 can manage about 2.1 or 2.2, more if flapped or with gurney's.
All the best,
JimC
I am not suppose to say anything, but someone is working on a new Super Cub wing with a much, much thicker airfoil (not the D&E's) wing. I don't think they will try to certify it, but they are building it and I think they want to use my aircraft to test it. This new wing also has a huge fowler flap, that will put all cub and modified cub flaps to shame. I have seen the drawings for the wings, but I am not building them so I have no control on the completion date. If they work like the consulting aero engineers that designed them claim, they will be the ultimate Super Cub wings. By the way, they are also supposed to increase cruise speed and the stall will be at a much lower deck angle. I have said too much.
Jerry Burr
MEMBER
Sedro Woolley, Washington.
Wing
Lockheed isn't the only Skunkworks. You just hear about them more than Portland.
Jim C. When comparing the USA 35B Modified, I had used the new AOA reference. Moving the leading edge forward 1 1/2" and down 1 1/2" and the AOA vers CL looks much better. With 60deg flaps only a small portion of the chord line is inside the wing section. The mean chord has awsome camber as compared to stock. ?? Jerry.
Lockheed isn't the only Skunkworks. You just hear about them more than Portland.
Jim C. When comparing the USA 35B Modified, I had used the new AOA reference. Moving the leading edge forward 1 1/2" and down 1 1/2" and the AOA vers CL looks much better. With 60deg flaps only a small portion of the chord line is inside the wing section. The mean chord has awsome camber as compared to stock. ?? Jerry.
leading edge cuff
Hi
Can some one explain deck angle to me.
AOA,is this the angle the wing meets the airflow?
Deck angle,I always assumed that this was the angle of the wing compared to the ground and changed by adding longer gear.I think i am out to lunch on this!!!!!!
AOI is the angle of the wing compared to the fuse.C/L and is changed by lowering rear spar mounts or raising front mounts?
From what i have read on this site i always assumed that a cuff would help to lower the nose on a 12 so that you would not have to be so nose hi on a slow approach.??Is this a false assumption?
With the cuff does the wing need a greater AOA to stall slower?
Does the wing slats also work on AOA or will the wing stall slower at the same angle of atack?
Anyway thanks for any response,Aurele
Hi
Can some one explain deck angle to me.
AOA,is this the angle the wing meets the airflow?
Deck angle,I always assumed that this was the angle of the wing compared to the ground and changed by adding longer gear.I think i am out to lunch on this!!!!!!
AOI is the angle of the wing compared to the fuse.C/L and is changed by lowering rear spar mounts or raising front mounts?
From what i have read on this site i always assumed that a cuff would help to lower the nose on a 12 so that you would not have to be so nose hi on a slow approach.??Is this a false assumption?
With the cuff does the wing need a greater AOA to stall slower?
Does the wing slats also work on AOA or will the wing stall slower at the same angle of atack?
Anyway thanks for any response,Aurele
