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Ailerons PA12 Vs PA18

Bill Rusk

Bill Rusk

BENEFACTOR
Sandpoint, Idaho
Folks

Can we change the ailerons on the Supercub and make it better?

I was doing a bit of SC.org research and came up with the following posts. These are taken out of context and pasted here as thought provokers. Are the ailerons on the PA12 really that much better? Is it just the LE shape of the aileron that makes all the difference or is it in the total bellcranks, pulleys, shape, system package? I do not really want to completely redesign the wing (and fuselage) but if all we are talking about is reshaping the aileron, hangars and false spar....then I would ask...why not?

Surely someone else has thought of this or done it. I understand the PA14 wing is similar to the PA12 wing. Yes/no? How does it compare to the SC.?

The next point is that if it is such a great idea why has it not already been done? We have a lot of flexibility with the experimental Supercub movement currently underway. Wayne Mackey, Calkins, Crash, Jerry Burr,.....you guys have a lot of experience. What do you think? Can we change the ailerons on the SC and make it better?

I think some development has been hampered by having to stay certified but in the last 7 or 8 years we have seen a great deal of innovative work with the SQ2, Carbon Cub, and thrustline development, widebodys etc.

Thoughts?

Bill


The PA-12 aileron is physically different than the PA-18 aileron (compare the leading edge of each), and this difference in combination with the cable routing and bellcrank system in the PA-12 make the Cruiser a MUCH nicer handling airplane. PA-12 ailerons are lighter and more responsive, and also offer a cleaner installation aerodynamically (and aesthetically) due to the fact that all the cables are internal.

The shape difference of the ailerons is the most noticeable difference. Some will say that this is the reason for more authority especially at lower speeds. My take is that while this may help---I see the big difference being the differential ailerons on the 12. Deflection being 31deg up and 25 down for a combined total of 56 degree range. The 18 is equal deflection up as down for a combined range of 36 degree (18 up 18 down). I have also suspected for some time that this difference contributes to the moose stall more readily in the 18 than the 12.

12 vs.18 wings
I've had about a dozen of each, and I've always felt that the 12 has a far better roll rate and aileron response.

Does this difference have anything to do with the quicker aileron response of the 12 ?

Russ, copy the PA-14 as close as you can. It has great performance with stock ailerons and flaps. It's roll rate is even faster then a stock PA-18 wing.


if you use the PA12 ailerons on yourPA18, you'll have to add the PA18 aileron horn the center hinge, or totally modify the aileron control system to the PA12 configuration. I would sell the PA12 aileronsand buy a set of PA18 ailerons. You might even be able to trade a set to someone.
Lot less trouble in the long run.

 
Bill, My 2c: While embedding the cables and horns so that they are not seen may be cleaner looking, I doubt that they contribute much, if any, less noticeable drag at the speeds that a Cub operates. The increased travel is likely to be responsible for a faster roll rate. Piper likely found that they wanted increased travel and could not accomplish it with the 18 cable routing as the horn became mechanically limited in its ability. More travel would have required a shorter horn along with higher control pressure. Thus the embedded horn and linkage. I feel that the shape difference that protrudes below the wing while the aileron is up increases drag enough to improve coordination thus requiring less rudder input. Would moving the ailerons outboard to a squared off tip give the 18 wing the same roll authority as a stock 12 wing thus eliminating the requirement of changing the entire cable/pulley system to match a 12?

What would happen if the angle if incidence were changed to that of a 12 coupled with Doug Keller's flaps? Would the cruise speed increase to that of a 12 while maintaining the take off and landing performance of a 18? For example: 12 shaped ailerons pushed outboard to the tip with stock 18 horn and cable routing, and with longer than stock extended split Keller flaps.
 
Bill Rusk said:
.....Is it just the LE shape of the aileron that makes all the difference
Click to expand...

on the aileron itself, LE is all that's different shape, ribs same length... different control hookup obviously..

nose of aileron dips bellow wing and directs air over top/through gap....

Bill Rusk said:
or is it in the total bellcranks, pulleys, shape, system package?
Click to expand...

travel is more one way than other with these, unlike an -18...and more travel overall...


Bill Rusk said:
I understand the PA14 wing is similar to the PA12 wing. Yes/no? How does it compare to the SC.?
Click to expand...
yes ribs(aileron bay) same 12/14 -NOT same as for -18....

a 12/14 rib is 1/4" LONGER behind rear spar than an -18 rib(flap bay), if I am not being dyslexic... if you want to use the -12/14 ailerons use these ribs then


edit...duh....

cost....
12 ailerons were almost $1300 each... -18 I remember much less.....
 
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Bill, Mark Englerth of "ThrustlineMod" fame has the answer to a simple improvement to -18 aileron authority here. I would strongly recommend talking to him or S2D or AgPilot about this. It's Marks baby, so I will not describe it here.

What Skywagon said about an extended -18 wing with a longer Keller flap and with a -12 incidence and -12 ailerons would be an interesting experiment.(slow-performance with the top-end of a -12??? probably not unless the landing gear was -12 also).

Also, as he said, the extended wing -18 with extended flaps and the ailerons moved out to the tip has decent roll rate, even without VG's, in my experience.

As Mike said, -12 ailerons are expensive.

No one mentioned the aileron cove (wing trailing edge) shape of the -12.
 
Dave Calkins said:
Bill, Mark Englerth of "ThrustlineMod" fame has the answer to a simple improvement to -18 aileron authority here. I would strongly recommend talking to him or S2D or AgPilot about this. It's Marks baby, so I will not describe it here.

What Skywagon said about an extended -18 wing with a longer Keller flap and with a -12 incidence and -12 ailerons would be an interesting experiment.(slow-performance with the top-end of a -12??? probably not unless the landing gear was -12 also).

Also, as he said, the extended wing -18 with extended flaps and the ailerons moved out to the tip has decent roll rate, even without VG's, in my experience.

As Mike said, -12 ailerons are expensive.

No one mentioned the aileron cove (wing trailing edge) shape of the -12.
Click to expand...


You mean that often forgotten part that is standard on a PA-12 and J5?

The cove on the PA-12 aileron is very similar to the -18 flap cove.
 
Tim, please respect the efforts of one of the wisest, kindest, most long-suffering gentleman that I know. Thanks. DAVE
 
Dumb question but does a 12/14 have a better roll rate because the wing is flatter, less diheadral ?

Glenn
 
Bill,
Here is a good side by side shot of the two profiles.

Marty57


aileron 14 vs 18.webp
 

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The goal is to take a stock -18 wing change the false spar and aileron LE to that of the -12 keep the same -18 cable routing and hinges/control horn system and increase aileron travel.

I have flown stock -18 wings with an additional 1" of up and down aileron travel and personally do not feel like they any roll faster than the standard travel ailerons. This would make me think that the extra travel or differential effect of the -12 system is what is increasing the roll rate. I would guess it's the different shape of the cove and LE on the aileron. The additional travel on the stock -18 setup seems to help when slow and in gusty conditions.

You can add more travel to the stock -18 system without modifying the center hinge/bell-crank but you may just get a little rubbing on the top of the wing from the control cable. I guess that is what teflon chafe tape is for.

Jason
 
This is a little off the subject. My supercub will have Colt wings and ailerons. I saw a PA-16 and liked the way the aileron
cable came up the strut across the bottom of the wing and attached to lower horn versus going thru the wing to upper
horn. Since I only have a front control stick I made a second torque tube aileron horn 180 degrees out with the first. I will
use the lower horn to work the stops and the upper horn connected to the cable going to lower aileron horn. The balance cable
will connect upper horns and go thru wing and fuselage behind the pilots head. This will be a simpler system, less parts,
and easier to adjust. I mainly did it because it required less alteration to the Colt wing.
 
2 cents. I find that the roll rate is best in the 12's and 5's with the stock wings. Trained one or two guys in each. When the ailerons are tabbed on either it gives the effect of sharper roll response for the input given vs. rigged for more throw. I find the latter more comfortable in those crappy crosswinds. The tabbed aileron is almost a fight against itself in a heavy, gusty, crosswind. The 18's are always slower in roll as a general statement. What is bad on both is using extended wing tips with stock ailerons. It would be easier to land those and just turn them on the ground. Another thing that I can always feel is drag in the pulleys from the 18 to the 12. Not a big thing but it always seems the 12's have less?? I would love to have a cub with the roll of a 12 or 5. My question is if you used the 12 ailerons for flaps any experimental guys do that? That shape sure seems to help?
 
PA-12 ailerons

A mate and I are both looking to build scratch-built Cubs. To fit into the New Zealand microlight system these will be something modeled along the 90 hp Super Cub.

We are looking at different ways of building ribs and we have realised that utilising a PA-12 aileron cove and aileron will simplify construction.


We would also like to have a more snappy aileron response, than that of a stock PA-18, just like you guys describe of the J-5 and PA-12.


So, I wonder if some of the following questions can be answered:
1. The PA-12 aileron cove is similar to the PA-18 flap cove. Similar does not mean the same. What is the difference?
2. Are the aileron hangers on the PA-12 the same length as on a PA-18?
3. I believe the PA-14 flap cove is the same as the PA-14 aileron cove. Which means it is different to the PA-18 flap cove. How does the PA-14 and PA-18 flap differ?
4. The PA-12 has a lot more aileron travel than the PA-18. Averaging the different up and down travel, the PA-12 has some 55.5% greater travel that a PA-18. So some of the greater response is due to the ailerons being higher geared. I have read in these pages that the PA-12 control arm on the torque tube is longer than that of a PA-18. So, is it the aileron cove shape that gives the greater response or is it the higher geared ailerons?
5. Higher geared ailerons = higher aileron forces. But then does the shape of the PA-12 ailerons lighten up the forces?
6. Can anyone advise of a source of drawings for the PA-12 rib, aileron and aileron ribs.... and PA-14 flaps?
7. Also wondering about, as part of all this, running the cables thru the wing like a TriPacer..... The TriPacer aileron horn is longer... the cable entering the wing at a sharper angle. Wondering if one might have to go to this style horn (and therefore cable run) to get the greater aileron travel...... comments??


Thanks in advance for your input.


Andrew.
 
Bill:

I built SC ailerons with PA-12 leading edges on my last cub. The one with the extended RV-10 fowler flaps. You have seen the plane, so has Dave Calkins, but probably didn't notice the ailerons. They fit tightly in to the SC cove with about 1/8 inch clearance. They have standard SC rigging. I swear they have a lot less adverse yaw compared to stock and good response. It is a square wing with 92 inch ailerons all the way to the tip.

Tim James
 
Last edited:
MainlandCub said:
A mate and I are both looking to build scratch-built Cubs. To fit into the New Zealand microlight system these will be something modeled along the 90 hp Super Cub.

We are looking at different ways of building ribs and we have realised that utilising a PA-12 aileron cove and aileron will simplify construction.


We would also like to have a more snappy aileron response, than that of a stock PA-18, just like you guys describe of the J-5 and PA-12.


So, I wonder if some of the following questions can be answered:
1. The PA-12 aileron cove is similar to the PA-18 flap cove. Similar does not mean the same. What is the difference?
2. Are the aileron hangers on the PA-12 the same length as on a PA-18?
3. I believe the PA-14 flap cove is the same as the PA-14 aileron cove. Which means it is different to the PA-18 flap cove. How does the PA-14 and PA-18 flap differ?
4. The PA-12 has a lot more aileron travel than the PA-18. Averaging the different up and down travel, the PA-12 has some 55.5% greater travel that a PA-18. So some of the greater response is due to the ailerons being higher geared. I have read in these pages that the PA-12 control arm on the torque tube is longer than that of a PA-18. So, is it the aileron cove shape that gives the greater response or is it the higher geared ailerons?
5. Higher geared ailerons = higher aileron forces. But then does the shape of the PA-12 ailerons lighten up the forces?
6. Can anyone advise of a source of drawings for the PA-12 rib, aileron and aileron ribs.... and PA-14 flaps?
7. Also wondering about, as part of all this, running the cables thru the wing like a TriPacer..... The TriPacer aileron horn is longer... the cable entering the wing at a sharper angle. Wondering if one might have to go to this style horn (and therefore cable run) to get the greater aileron travel...... comments??


Thanks in advance for your input.


Andrew.
Click to expand...

yes same SHAPE as -18 flap cove but -1/4" LONGER?/SHORTER rib length behind rear spar..... don'T remember which.....
 
Bill, After a conversation with Jerry Burr, I came away with the understanding that the most significant fault of the the -18 aileron was the excessively wide gap between the wing and the aileron. (especially on the inboard end) Extending the flap gap seals to the aileron (as per Crash) results in increased aileron response. (never tried it myself) Looks nice, too....
 
I made an outline tracing of my PA12 aileron leading edge and the PA18 style flap on the 12. I think the PA18 has the same leading edge on the aileron as the flap. You will notice that the 12 leading edge is much sharper. On my PA14 experimental replica project I plan on using the D&E aluminum extrusion for the aileron. I have wondered how to convert it to the 12 style leading edge. I am considering forming a wooden edge and bonding it to the aluminum extrusion before covering the aileron. Anyone have a wood moulding cutter? Any thoughts? Sorry but the image upload doesn"t seem to be working.
 
jimboflying said:
I am considering forming a wooden edge and bonding it to the aluminum extrusion before covering the aileron. Anyone have a wood moulding cutter? Any thoughts?
Click to expand...
I made a wood fairing using balsa for the leading edge of my rudder to fill in the gap to the fin. Cut the concave side with a table saw by running the wood strip at an angle through the blade. First clamp two fences on either side of the blade at an angle. I used a couple of pieces of strapping for the fences. It takes some experimenting to get the angle and blade height setup correct. Run several test pieces until you are satisfied. The saw blade is not as happy cutting sideways as it is running straight through so you will have to make progressive passes. Using this method I was able to get a fairly accurate match to the curvature of the tube. The other two side angles are cut using the table saw in it's normal manner. I used Stewart's fabric glue to fasten the wood to the tubing. Then finish the desired shape with sandpaper. I also used balsa covered with fabric to replace the aluminum fairing between the top of the flap and the wing. For this I used the flap as a sanding block to get a good match to the shape of the flap leading edge allowing for the fabric thickness. The result is a good tight seal when the flaps are up. I am planning to use a strip of Teflon tape (available from Aircraft Spruce) to prevent chaffing of the fabric between the wing and flap.
 
i have a set of 12 wings for my Javron Cub, which i bought as an unfinished/unstarted/unsighted project. i didn't understand what i was getting until late in the proceedings, but after reading this post, i'm keen to get going with them. i have already sent photos of the bellcrank assembly and lightening holes to one of the members of this group. if anyone else is interested PM and i'll send more. like 'Mainland Cub' i am looking for any information relating to the 12 wings, rigging drawings and setup. i take particular note of his comment regarding the length of the arm on the 12 torque tube versus that on the 18. if anyone can shed some light on this i'd like to know. it will be much easier to set it up now with the correct length arms. are the 12 drawings available in the public domain??
thanks,
Phil
 
Aileron Cables.

pfjay52 said:
i have a set of 12 wings for my Javron Cub, which i bought as an unfinished/unstarted/unsighted project. i didn't understand what i was getting until late in the proceedings, but after reading this post, i'm keen to get going with them. i have already sent photos of the bellcrank assembly and lightening holes to one of the members of this group. if anyone else is interested PM and i'll send more. like 'Mainland Cub' i am looking for any information relating to the 12 wings, rigging drawings and setup. i take particular note of his comment regarding the length of the arm on the 12 torque tube versus that on the 18. if anyone can shed some light on this i'd like to know. it will be much easier to set it up now with the correct length arms. are the 12 drawings available in the public domain??
thanks,
Phil
Click to expand...

Hi Phil,

Sounds like you're thinking of retaining the belcrank and the differential ailerons. How were you thinking of running the aileron cables?

There was some info on this site about the torque tube arm length. I will find it and post it.

What flaps do your 12 wings have?

Andrew.
 
behindpropellers,
if this is wrong, what is correct? i'm confused... here is a quote from that link:

"The PA12 aileron travels are determined by the bellcrank stops in the wing. They are not adjustable. The bellcrank "has" to be centered to obtain the correct travels. You also have to have the extension on the bottom of the torque tube.
The PA18 is different. The travels are set by the bracket that's attatched to the center aileron hinge. The reason that the PA18 travels are equal in both directions is that they are not differential ailerons like the PA12."
cubsunlimited@verizon.net

can you tell me or show me some photos of how this is set up?
thanks,
Phil
 
Mainland Cub,
thanks, yes, i plan on keeping the full 12 system. my airframe is set up like the 12. i think! i've never taken any notice of the 12 cable routing, but looking at some photos from Cubus Maximus i think i have pulley mounts set up on the airframe, that will run up the front of the 'D' window, over a pulley and into the wing.
i have a hybrid setup as described here, Cub wings and 12 flaps with a 4" extended chord. the flap cove is definitely different to the aileron cove by about 1/4". as i am away i can't run a tape measure over them, but i can send you some photos once i return home in a few weeks?
cheers,
Phil
 
The J-3 and PA-12 torque tubes are the same. The PA-12/J-5 TT has an extra hole drilled in it. A tab is connected to extend the throw.

I have all of the math differences written down somewhere from when I was working with a DER to get the PA-18 elevator system in my J-5.

PC060012-1.webp
 

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behindpropellers said:
The J-3 and PA-12 torque tubes are the same. The PA-12/J-5 TT has an extra hole drilled in it. A tab is connected to extend the throw.

I have all of the math differences written down somewhere from when I was working with a DER to get the PA-18 elevator system in my J-5.

View attachment 6120
Click to expand...

actually, ......

the bottom is as you show on normal -12, but the Top stick pivot bolt(elevator) is higher than a newer cub.... OLD cubs were like a -12
 
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