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Building an Experimental PA11

Question for you all on struts....I have a set of Supercub struts...one side are the sealed ....the other side not, so I need to decide a couple of things.....do I buy new sealed set for the one side and have a complete set of sealed supercub struts on my 11 or do I sell the sealed ones and buy a set of sealed J3 struts? Another option is aluminum all around....the supercub struts seem like overkill and I could save some weight by just buying new J3 struts.....one more question...wonder what the weight difference Is between sealed J3 struts And Aluminum?
 
For that little -11 the supercub struts would be overkill IMO. They're certainly more than strong enough but you're adding a good bit of weight. J3 struts on the other hand are going to save a good bit of weight over -18 struts but the downside is you have to be careful about parking outside in a wind storm or heavy snow as you could bend them pretty easy if you get a negative load on the wings.

The -18 aluminum struts are a great product and are similar in weight to J3 struts (maybe a little lighter, don't have a set of J3 struts to weigh) while still being as strong as -18 standard duty struts. Downside is obviously cost but if you have the money and are willing to put it into a really nice cub build (which it appears you are) there aren't really any downsides to the aluminum struts and if going experimental that saves you $500 not buying the STC.
 
The -18 aluminum struts are a great product and are similar in weight to J3 struts (maybe a little lighter, don't have a set of J3 struts to weigh) while still being as strong as -18 standard duty struts. Downside is obviously cost but if you have the money and are willing to put it into a really nice cub build (which it appears you are) there aren't really any downsides to the aluminum struts and if going experimental that saves you $500 not buying the STC.
What is the source of these certified -18 aluminum struts? Are they an Alaska thing? I've only seen recent mention of a certified version without any mention of a source.
 
Curious what the weight difference is between J3 struts and Super Cub struts. I might have to go dig around in the loft of one of the storage hangars to find out. I do know we put -18 struts on an -11, they are more streamlined and he wanted them because they were faster.
 
Yeah, I'd be curious as well. The J3 struts are pencil thin and small compared to -18 struts. I would imagine the weight difference is significant.
 
Stock PA-11 lift struts are wider and more streamlined than J-3 struts. The originals are about the same cross section as PA-18 struts. Piper did that in addition to lowering the engine mount and adding a pressure cowl, more raked windshield, and streamlined bungee covers to get a little more speed from a basically J-3 airframe [in fact, the first several PA-11s used J-3 fuselages that were modified on the production line]. All that amounted to about 7 MPH with the same engine and propeller as a J-3.

It still can't catch an Aeronca Champ with the same engine and prop, is still more difficult to get into, and is still not as easy to land. Nonetheless, I have Aeronca to thank for inducing Piper to improve the J-3. Champs are great airplanes, but I prefer flying the Cub.
 
....is still more difficult to get into, and is still not as easy to land...

I've found getting into the rear seat far easer than the front. Almost makes it seem like the piper double folding door was designed for entry/exit of the rear seat primarily...hmmm

Good info on the PA-11 struts. I had thought all along that the J-3 and the -11 used the same struts.
 
PA-11s may be soloed from either seat and remain well within the C.G. envelope [moving the fuel tank from the boot cowl of the J-3 to the left wing of the PA-11 allowed that]. I think most folks fly them from the front because, unlike a J-3, you can see over the nose from that seat. That's where I fly it from except when doing a Cub act. I prefer flying from the rear seat then because the airplane "feels" better from that seat during extreme maneuvering. I don't know if I have a definitive reason for that, but it does. Maybe because the C.G. is a little farther aft and there is slightly less pitch stability or because there is more structure in front of you to frame the sight picture.
 
Same here, I far prefer flying from the rear but that's mainly because I have to because I've got a nose tank to contend with. The plane for sure feels better with an aft CG; far more responsive. I think another piece to that puzzle is that you feel the pitch and yaw for more being behind the axis of rotation so you tend to fly the plane a little more "square" from the rear seat.

But really, I'm just poking fun about flying from the rear. The more I look at cubs the more I realize how much of the plane was designed around flying from the rear seat like the brake cylinder location, door and step design, rear seat design, parking brake arrangement, and left window design. The later iterations just moved the pilot to the front seat and then slowly adapted the front seat and controls to being equal to the rear seat setup. The addition of these steps on the landing gear to be able to enter/exit the front seat is just one example of how the plane really wasn't designed around front seat usage but the aftermarket stepped in to adapt it. Just an interesting way the design changed.
 
Stock PA-11 lift struts are wider and more streamlined than J-3 struts. The originals are about the same cross section as PA-18 struts. Piper did that in addition to lowering the engine mount and adding a pressure cowl, more raked windshield, and streamlined bungee covers to get a little more speed from a basically J-3 airframe [in fact, the first several PA-11s used J-3 fuselages that were modified on the production line]. All that amounted to about 7 MPH with the same engine and propeller as a J-3.

It still can't catch an Aeronca Champ with the same engine and prop, is still more difficult to get into, and is still not as easy to land. Nonetheless, I have Aeronca to thank for inducing Piper to improve the J-3. Champs are great airplanes, but I prefer flying the Cub.

That’s what I thought when I read this thread as well: the 11 struts are different from the J 3 struts

MTV
 
According to my 85 YO buddy Ray who has owned 4 or 5 Pa11s, the first ones in 47 had J3 struts till they were used up. Piper didn't waste anything. Mine was the 11 built and had J3 struts. Don't forget that the jury strut clamps are different also

Glenn
 
What is the source of these certified -18 aluminum struts? Are they an Alaska thing? I've only seen recent mention of a certified version without any mention of a source.

8962a7048f89df7016952c785e653a09.jpg


Airframes Alaska. 12.5 lbs lighter than Univair sealed supercub struts

https://www.airframesalaska.com/Aluminum-Struts-s/2061.htm


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There's nothing on the instructions, STC, or ICA regarding wind or snow. The only difference is that they are more similar in strength to stock or standard duty lift struts than they are to the heavy duty lift struts.

So basically, just make sure to not neglect your plane and let snow build up on it and you should be fine. For very windy areas obviously tying down with the nose to the prevailing wind would be necessary. I know there are folks who need the extra strength of the HD struts for windy areas or if the plane is not attended and allowed to get a bunch of snow on the wings but that's why the HD struts exist and those would be a better option for that type of customer than the aluminum struts.
 
According to my 85 YO buddy Ray who has owned 4 or 5 Pa11s, the first ones in 47 had J3 struts till they were used up. Piper didn't waste anything. Mine was the 11 built and had J3 struts. Don't forget that the jury strut clamps are different also

Glenn

Yep, that’s the story I was told as well.

MTV
 
There's nothing on the instructions, STC, or ICA regarding wind or snow. The only difference is that they are more similar in strength to stock or standard duty lift struts than they are to the heavy duty lift struts.
This is the STC:
https://www.airframesalaska.com/v/vspfiles/pdf/STC PA-18 Aluminum Struts.pdf
What about 4) ...compatible, up to 2000 lb. gross weight...?
I realize they were only certified to 2000 lbs because the highest -18 certified gross weight is 2000 lbs and for simplicity and working with FAA there was no need to prove more strength.
A large number of the E-AB Cubs are rated at 2300 lbs or more. What is the manufacturer's recommendation for the higher gross weight use?
Do you know if they were tested in comparison to the conventional steel struts or just to the anticipated 2000 lb loads?
 
I never realized that PA11 struts were so much different in profile than J3 struts....I saw the 2 listed in the catalog but Never really thought about them being that different. I like the idea of weight savings of Aluminum...12 lbs is a nice number....but i realize that is for 18 struts....I’m still curious of the difference between those and 11 struts in weight...maybe I’ll call univair and see if they know.
 
The other Nice thing about the front seat of the 11 vs J3 is the elimination of those damn diagonal support tubes for the nose tank.....they really suck, especially with winter boots on
 
According to my 85 YO buddy Ray who has owned 4 or 5 Pa11s, the first ones in 47 had J3 struts till they were used up. Piper didn't waste anything. Mine was the 11 built and had J3 struts. Don't forget that the jury strut clamps are different also

Glenn

Not according to Clyde Smith.

Think about it; Piper was trying to clean uo the Cub to get more speed from the airframe. They spent time and money trying several ways to do this by trying mods out on a J-3. They found that streamlining the lift struts made a noticeable improvement in drag. As you can see from the photos of the 2 prototype PA-11s [s/n 11-1 NX91913 and s/n 11-2 NX2000M] in Roger Peperell's book, they had the more streamlined struts. They were both built in 1946 and production didn't start until March of 1947. Since the design approval was issued by the C.A.A. in October of 1946, it is unlikely and would have been illegal for Piper to deliver the airplane with J-3 struts on it.

Regarding old buddies and folks that have owned 5 of the type, I speak with authority (because of my own advanced age) when I say that just because you are old doesn't mean you are right.
 
I speak with authority (because of my own advanced age) when I say that just because you are old doesn't mean you are right.

I had to chuckle at your comment. My Dad is 82 and when someone comments they have been doing something X number of years his comment to me is they could have been doing it wrong al those years. :)
 
Curious what the weight difference is between J3 struts and Super Cub struts. I might have to go dig around in the loft of one of the storage hangars to find out. I do know we put -18 struts on an -11, they are more streamlined and he wanted them because they were faster.


Sealed J-3 univair struts, painted no clamps:
Rear: 6lb 13oz
Front: 8lb 14oz
Total 31lb 6oz

Airframes aluminum un painted no clamps:
Rear:4lb 5oz
Front: 8lb 10oz
Total 25lb 14oz


Non sealed Pa-18 painted no clamps
Rear: 6lb 12oz
Front: 11lb 3oz
Total:35lb 14oz

10Lb difference in stock non sealed struts and airframes aluminum. They advertise 11.5. That's about on par with what I have see with buy my product and save X in weight is usually on the high side. Guess i should have weighted the sealed struts. Maybe someone else can. And feel free to check my math, I may be off
 
Lift Struts
Airframes:
Front PA-18 No oil, no paint 11 lbs
Rear PA-18 No oil, no paint 9.5
Front PA18 with oil and paint 11.5
Rear PA18 with oil and paint 10
Univair sealed Struts, painted as removed:
PA18 Front 11
PA18 Rear 7
Aluminum struts advertised 18 lbs lighter than AF and 12 lbs lighter than Univair.
Univair set of struts primed and painted 40.6 lbs.
Airframes aluminum struts no paint 28.2 lbs.
 
Wow! Supercub.org contributors ARE THE BEST! So is it the new cool to put unpainted aluminum struts on? Decisions decisions.
 
Almost pulled the trigger on some AF Aluminum Struts today....They mentioned potential difference between J3/PA11 jury strut vs PA18....only difference is built in pitot right? also shipping cost on struts sorta sucks...$330.....Anyway, I think this is the way to go still. Any thoughts?
 
Would be nice if someone posted the weights of javron. I heard they are heavy and I think they use a front strut on the rear too


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Pretty sure it’s on my thread somewhere.
They definitely do not use a front strut on the rear strut. Without looking through my thread, I’m pretty sure that they are lighter than the heavy duty strut set, but a little bit heavier than the original strut set.
Bill
 
Have you checked with Carlson in Ohio for al. strut material? They are a good small company to do business with.
 
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