Piper wing ribs

[EDMO 1078]

Leni,

     I forget where it was posted, but you were comparing the PA-12 cruise with the slower PA-18, and talked about the change in incidence:

I don't have documentation on this, but I believe the PA-12 had the Clark Y ribs, like the J3, and the 18 was changed to the NASA (something) 35  or one of the NASA Dud patterns - This could be why the 18 was slower in cruise even with a lot more horsepower?

EDMO

Edited 6 Sep 2014 by Ed In Missouri

[akflyer 1427]

No.... before john stoner died, he was building the ribs for Dakota cub at his hangar in soldotna. I spent a good bit of time with him there going over some drawings they had, one of them being an overlay drawing of an 18 fuse over the 12 to show the difference in the aoa. They both use the USA 35B airfoil.

[EDMO 1078]

Thanks Leni,

     I knew Piper had changed the rib design after using the Clark Y - but guess incidence made the difference.

EdMO

[Luked 71]

Ed, I remember looking this up one time and one person on a forum somewhere mentioned that lots of people assume that the cubs have the Clark Y because it looks so much like the USA-35B. That must be accurate because I did a quick google search and found this quote from Flying magazine.

 

 

Taylor chose the lightly loaded USA-35B airfoil for the E-2, a design that provided good low-speed flying qualities — it was reluctant to stall and provided plenty of warning before it did. All Cubs, including the J-3 and Super Cub, have used this same airfoil shape. For this reason, the Cub is a forgiving airplane in the hands of a novice and downright divine with a skilled pilot at the helm.

 

 

Read more at http://www.flyingmag.com/aircraft/pistons/piper-cub#TQ6rMDEBjmJp22h4.99

 

Edit: Flying doesn't mention it, but I read in other sources, they mention that some cubs used a USA-35B (modified) because they added 4% to the top surface ordinates.

Edited 6 Sep 2014 by Luked

[EDMO 1078]

Luke,

    I thought that there were two different ribs used on the Cubs - but thought the change to the 35 came with the late J3 and for sure on the PA-18 SuperCub.  I didn't know what Taylor used.

    I wonder if the rib type is listed on the TCDS for each plane?   I never checked them for that.

Thanks,

EdMO

Edited 6 Sep 2014 by Ed In Missouri

[Luked 71]

Well I read it on the internet, so it must be true... 

[akflyer 1427]

I don't need a tcds to tell me what I know first hand from working with a wing manufacture and limited involvement in subsequent testing and certification on the Yankee cub. I had the original drawings and subsequent updated drawing to study. A quick Google search will net you a whole lot of hits that state the USA 35B.

[EDMO 1078]

Leni,

    I wasn't saying that anyone was wrong - I just wondered if the TCDS on every plane lists the wing rib profile - I had never searched them for that.  Sorry if you took it different than what I was trying to say.

EdMO

[akflyer 1427]

nope, I didnt take it any different.  hmmm... maybe I should have said... Badges... we dont need no stinking badges...    I doubt that the rib profile is listed on the TCDS, but it may be.  I do know its on the factory drawings.  Look up Steve Pierce he can probably tell you where to find the info.  He is in Graham Texass at http://www.pierceaero.net/

 

[EDMO 1078]

Leni,

        I was not referring to the Piper 35B ribs when I wrote about the TCDS info - I was curious about the wing profile on my Maule, Ercoupe, Cessna,  and any other plane that I might be interested in finding the wing profile.

EdMO

[akflyer 1427]

https://store-dtwuls.mybigcommerce.com/content/a-787_rev33.pdf

 

TCDS for ercoupe... I have not seen one on any of the planes I have researched (cessna, piper etc.) that listed the wing profile or airfoil. 

 

You can google just about any TCDS for any aircraft and download it.

 

I had to do this on the 180 when I was arguing the use of the 1 1/8" tail spring versus the .875" tail spring.  take you back to CAR3 not current regs..

[Luked 71]

Hey Ed, check out this site:

 

http://aerospace.illinois.edu/m-selig/ads/aircraft.html

 

It's a pretty complete list.

 

Hint: press ctrl+F and type in the name of the aircraft you want to search the page.

 

I just searched for the Maule on that page, and it looks like all models used the good old USA 35B mod.

Edited 7 Sep 2014 by Luked

[EDMO 1078]

Thanks Leni and Luke for the info.

     I have the TCDS on both the Ercoupe 415C/D and the Maule M4C, and maybe the Cessna 150 and 182 - The are stored with my many books and papers, and I haven't looked at them for a few years.   Not really too worried about it now that they are all gone - Got to think about this Monster I have been building for a few years with the Eppler/Riblett/Ashby wing ribs and get it finished.

Looks like you hit the Jackpot of info Luke!

EDMO

Edited 8 Sep 2014 by Ed In Missouri

[Av8r3400 1179]

Cool website, Luke...

[akflyer 1427]

Sweet site Luke!! Thanks for posting that one!

[Luked 71]

Yeah, it's kind of fun to just scan through and see what they used on various famous planes. It's also interesting to see how popular some airfoils were. It makes you wonder how critical airfoil selection really is on your average GA plane.

 

Most people probably noticed this,  but just in-case you didn't, there is another part of the site that has all of the airfoil coordinates:

 

http://aerospace.illinois.edu/m-selig/ads/coord_database.html

 

If you just want to see what an airfoil looks like, you can also click on the gif file to see a plot of it.

Edited 8 Sep 2014 by Luked

[EDMO 1078]

Leni,

    Guess we stirred the pot enough to  get some really good info posted - Thanks to Luke!

Maybe you could put the info posts in "Files and Forms" so they are easy to find?

EdMO

Edited 8 Sep 2014 by Ed In Missouri

[akflyer 1427]

I am wondering just how the ole avid would do with the USA 35B ribs... I have been kicking around the idea to build a new set of wings using the KF IV profile but I may give this some thought

[EDMO 1078]

Harry Riblett would probably say, "You Digressed" !   The Cubs don't set any speed records!

EdMO

Edited 8 Sep 2014 by Ed In Missouri

[akflyer 1427]

I have the 180 for speed.  The avid is purely STOL fun flying, and was never intended to be a CC machine.  Nothing so far seems to be able to beat a cub in STOL competitions... Infact, the cub guys have certainly SPANKED the hell out of the guys with 200,000 super duper latest and greatest STOL machines.. That makes one stop and wonder if old Mr Taylor just got it right and some things really cant be improved on.

 

When a 95 HP cub (stripped down and super light) keeps kicking the ever loving shit out of the SQ's, Highlanders, Carbon Cubs etc, one must take note that maybe that wing is just one of the best ever developed for STOL work.  99% of the guys that work cubs for a living prefer the straight wing with no mods to it.. why? because it works day in and day out and does not have nasty habits.

 

Just something to ponder on

 

[Luked 71]

One other point for the cub wing is that it's kind of like the chevy 350 of wings. There is a ton of accumulated knowledge about them. There has been a lot of experimentation and improvement on them. And, there are lots of suppliers that offer many types of parts for them. Even if it wasn't better than the Avid wing, these would be big points in it's favor.

[EDMO 1078]

I almost knew you wanted the STOL advantage and not speed - But what about the huge difference in wing chord/span compared to the Cub???  How much could the smaller 35B wings do over what the undercambered already does?  Just thinking and writing...

.

What about the high-lift / slow cruise wings used on the Zenith 701/ 801 - It gets off the ground quick?

 

Longer wings and bigger flaperons plus slats or extended leading edge with the undercambered might be just about the best stol you could get out of our small birds.

EdMO

Edited 10 Sep 2014 by Ed In Missouri

[cliff 45]

 I have the same opinion as akflyer. These planes were designed for recreational flying not long cross country flying. Why do you think the wings fold, so you can drag them cross country, unload, unfold, and enjoy. I never understood the people who take a 2 stroke airplane and add long range fuel tanks, landing lights, every bell, gadget and whistle possible to a plane they will never fly at night or on long cross countries. locally, we have several grass fields that we hop in the light planes and go visit. All are with in 20 miles and that is pretty much the extent of our little groups cross country flying. When I am traveling I fly my Cessna. If I have to go to a light sport license in the future I will buy the fastest LS I can afford and use it for cross country work. If you are flying a  2 stroke Avid or Kitfox on long cross country flights, it is because you love the adventure not the speed, comfort, and reliability these planes provide. Tweaking them is fun, but they are what they are.

[Guest]

I flew my little 582 powered MKIV all over the Western US and enjoyed every minute of it. No IFR bells and whistles, no long range fuel tanks. I could carry a small whitewater kayak and all the camping gear I needed to spend multiple days away from civilization. A lot of fuel stops, but that was fun too! I did not have multiple planes to choose from, and I suspect most folks don't. Just because you don't own a plane ideally suited to a particular mission does not mean you shouldn't undertake the mission does it?

[Guest]

Oops! Re-read your post where you say "If you are flying a  2 stroke Avid or Kitfox on long cross country flights, it is because you love the adventure not the speed, comfort, and reliability these planes provide."

 

You are correct. If I owned a cross country cruiser there are definitely times I would have chosen to take it! I thought you were saying cross country is not what they are designed for and you cannot understand why anyone would do it with one. I did it because it was the only plane I had......and I do enjoy the adventure which is a bonus.