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FixedWing
06-08-2004, 02:16 PM
I want to take a close look at the various component parts that go into a Super Cub to see where it might be possible to save weight using, for example, alternative materials. To do this I?d like to get some idea of where it might be fruitful to look.

I know from reading here that the minimum weight on a more powerful, high performance, but light weight, Super Cub is about 1050 lbs. But what are the weights on the various parts that go into making that up? Specifically:

Fuselage
Wings (Dakota slatted or equivalent)
Rudder
Elevator
Engine
Instrumentation (basic and light IFR)
Interior seats
Other interior parts (inner walls, floor, etc)
Battery
Brake system
Landing gear
Fabric & paint covering
Windows
Rigging
Wing struts

And anything else I?ve missed.

Once I have an idea where the weight is going, then I want to start thinking about where it might make the most sense to look at removing that weight.

Thank you! :)

Stephen

cubunltd
06-08-2004, 02:53 PM
Stephen,
From your list, there is not a lot you can save. A few pounds maybe. You might be able to save a pound or two with your selection of instruments, light weight battery. A standard battery weighs around 27 lbs. A light weight one about half that. you can save about 20 lbs. depending on what paint process you use. Interior cushions don't weigh much to begin with. The rest of your list I wouldn't mess with as you need the strength in the remainder of the components. You can save some pounds by using a wooden propellor, but you "may" be giving up a little performance. I've not yet flown a Supercub with a wooden prop so I can't say for sure, but I have flown a lot of J3's with a wooden propellor and they don't match the performance of a metal prop.
cubsunlimited@verizon.net.

FixedWing
06-08-2004, 03:26 PM
From your list, there is not a lot you can save. A few pounds maybe. You might be able to save a pound or two with your selection of instruments, light weight battery. A standard battery weighs around 27 lbs. A light weight one about half that. you can save about 20 lbs. depending on what paint process you use. Interior cushions don't weigh much to begin with. The rest of your list I wouldn't mess with as you need the strength in the remainder of the components. You can save some pounds by using a wooden propellor, but you "may" be giving up a little performance. I've not yet flown a Supercub with a wooden prop so I can't say for sure, but I have flown a lot of J3's with a wooden propellor and they don't match the performance of a metal prop.

I'm trying to think outside of the box here. What seems to make the Super Cub so great is that it has become generic where you can pick and choose the carious components that make it up. This is great! And I've been paying attention to which components can be put in and which can be left out.

But what I'm trying to think more about now is using alternative materials. Actually changing what it is that goes in. For example, sports motorcycles moved from steel frames to aluminium to save weight almost a decade ago. Could the same be done for a Super Cub fuselage? If so, how much weight would be saved? Similarly, all of the wing components have been made out of aluminium ? mostly sheet aluminium. Could composite carbon fibre be used instead? If so, how much weight could be saved? Ditto for the seats ? they seem to be made out of steel. They?re not structural. So could this be made out of aluminium or composite material? The list goes on and on.

Saving weight is all about money. I?d like to start thinking about where the potentials are and how much it will cost to get the weight out.

Stephen

cubunltd
06-08-2004, 04:21 PM
I see where you are going, however in order to make an aluminum fuselage , the tubing sizes would have to increase along with the wall thicknesses to maintain strength and rigidity. An aluminum fuselage would also not take the flexing for very long. An original fuselage weighs about 110 lbs. so how much could you save? 10 lbs.? Is this worth the extra effort and time that it would take? A lot of aluminums are not weldable, so you would have to make sure you got the right spec.
The seat for in fact is structural in so far as the force it takes when you crash. You definitely don't want it to come loose on impact. you could use some composite materials on the interior panel and save a pound or two. Hey keep thinking, but don't compromise safety for a few pounds.

HydroCub
06-08-2004, 04:53 PM
I found the way to take 50# off my Cub at the Border's bookstore.

Answer is in the "health" section...... The Atkins Diet...!!

FixedWing
06-08-2004, 05:23 PM
I see where you are going, however in order to make an aluminum fuselage , the tubing sizes would have to increase along with the wall thicknesses to maintain strength and rigidity. An aluminum fuselage would also not take the flexing for very long. An original fuselage weighs about 110 lbs. so how much could you save? 10 lbs.? Is this worth the extra effort and time that it would take? A lot of aluminums are not weldable, so you would have to make sure you got the right spec.
The seat for in fact is structural in so far as the force it takes when you crash. You definitely don't want it to come loose on impact. you could use some composite materials on the interior panel and save a pound or two. Hey keep thinking, but don't compromise safety for a few pounds.

I agree completely on the safety issue.

If it is 110 lbs and only a savings of 10 lbs then definitely not worth it.

For the seat, I'm wondering if carbon composite might make more sense. It would be a lot stronger. The weight savings would be significant. How much? I don't know.

What I want to do is get some ideas of the numbers involved and then show photos of the various pieces to my auto racing friends. They will be able to look at those pieces and tell me 1) how it might be done, 2) how much weigh might be saved and 2) whether it would be safe.

Maybe nothing can be done. Maybe the Super Cub is already as light as it reasonably can be for the price. But I'd like to at least take a look at it and see.

Stephen

FixedWing
06-08-2004, 05:29 PM
I found the way to take 50# off my Cub at the Border's bookstore.

Answer is in the "health" section...... The Atkins Diet...!!

Yes, but what about all of that meat you've got to carry around with you??? :crazyeyes:

Stephen

HydroCub
06-08-2004, 06:07 PM
I found the way to take 50# off my Cub at the Border's bookstore.

Answer is in the "health" section...... The Atkins Diet...!!

Yes, but what about all of that meat you've got to carry around with you??? :crazyeyes:

Stephen


That's why you carry a gun and a fishin' pole...!!

cubunltd
06-09-2004, 11:06 AM
Not to take anything away from your racing buddies, but they are not airplane designers and their butt isn't up in the sky with you. If one of their ideas doesn't work on a race car, they pull over. I used to build race cars and motorcycles also and what may apply to a race car doesn't necessarily apply to an airplane. Stresses on a race car are different then on an airplane. I would urge you to take the advise of people on this sight who have experience with building and modifying airplanes. You are not the first to try and make a supercub as light as possible, but there is a limit. Once again, I don't mean any disrespect to you race car friends, I'm sure they are very good in what they do, but they are not airplane builders.

FixedWing
06-09-2004, 12:05 PM
Not to take anything away from your racing buddies, but they are not airplane designers and their butt isn't up in the sky with you. If one of their ideas doesn't work on a race car, they pull over. I used to build race cars and motorcycles also and what may apply to a race car doesn't necessarily apply to an airplane. Stresses on a race car are different then on an airplane. I would urge you to take the advise of people on this sight who have experience with building and modifying airplanes. You are not the first to try and make a supercub as light as possible, but there is a limit. Once again, I don't mean any disrespect to you race car friends, I'm sure they are very good in what they do, but they are not airplane builders.

I think you are totally right. I just want to take a look at the idea. I haven't actually decided to do anything. Information, thought and discussion are good things, right?

Stephen

cubunltd
06-09-2004, 01:49 PM
You're right Stephen, Thoughts, discussions, ideas and thinking out of the box also is what it's all about and it's all good.
Do you own/fly a supercub now?
cubsunlimited@verizon.net

FixedWing
06-09-2004, 06:44 PM
Do you own/fly a supercub now?

I have absolutely no experience with SuperCubs.

That is frankly why this interests me so much. It represents to me something that I can learn a great deal about. The skills necessary to build something like this are skills I do not have and will need to learn if I am going to be successful. When the SuperCub is built, I then will be able to learn a completely new set of flying skills that otherwise I could never learn. And finally, it will also give me access to places that until now have been inaccessible to me and I want to learn about that too.

Also, because so many of you are here actively doing this and because there is such a free flow of information on this topic, both on this site and in general, this is another reason why I?m interested in this project. I want to learn but I?d rather not learn the hard way. So it is precisely because of all of the skill and experience that you and others possess that I do feel like I can take on a project like this.

Stephen

Crash
06-09-2004, 09:37 PM
You first have to figure out what the mission of this airplane will be, then build it in that direction. I have found there is a trade off to just about everything, including light weight. Our Cubs in Alaska tend to weight a bit more then "outside" Cubs because we use heavy duty parts and large tires that tend to take the weight up. You can get one real light but you give up "bush" use-ability or comfort (push button starter) in the process. As I said before, everything is a trade off and most of the weight saving ideas have already been tried hundreds of times already. Crash

cubunltd
06-10-2004, 08:38 AM
Crash is absolutely right. Build the airplane for the mission. I'll be happy to help you in any way I can as I'm sure everyone else on this sight will. You can email me if you want with any questions.
cubsunlimited@verizon.net

P.S. Are you really from Mars?

FixedWing
06-10-2004, 10:24 AM
Crash, Unltd, I know you are both right. And yes, most of my thinking has been going into figuring out what I want and what is out there already that can meet those needs. I do know that my SuperCub is not going to be the lightest Cub possible. As Crash says, once you design a plane for a mission it takes on additional weight.

If I really wanted the lightest Cub possible then I?d probably build that experimental J-3 Cub with a turbine engine pictured on the turbine thread. :grin:

In a way, I regret posing this question now. It has obviously produced an unintended reaction from SuperCub guys like yourselves. Really, the only reason I asked it was that this is information that I cannot already find by searching the archives. A lot of the standard stuff is there for me to read about and I think I have a duty to at least do some research there before asking questions. But this topic is new.

And no, I?m not from Mars. I?m in Connecticut at this moment but will probably be in Europe soon. My home is in Hongkong. I travel quite a bit. I got into the habit of putting ?Mars? for locale when posting on a number of car enthusiast boards. Nice cars have a way of vanishing a lot more frequently than do SuperCubs. Unfortunately, secrecy is sometimes necessary.

Stephen

cubunltd
06-10-2004, 03:25 PM
Stephen, the reaction wasn't meant to be negative in any way. The only way to learn about something is to ask questions. The only dumb question is the unasked one. Besides if you hadn't posed the question, you might not have had the opurtunity to talk with two nice guys like Crash and myself...... Seriously, I'm in western Pennsylvania and we're not that far away. Come visit me and take a look at some of my projects. I'll supply the burgers and beer!

John

P.S. You're invited too Crash..and anyone else that wants to come.
cubsunlimited@verizon.net

FixedWing
06-10-2004, 05:06 PM
I'm in western Pennsylvania and we're not that far away. Come visit me and take a look at some of my projects. I'll supply the burgers and beer!

That sounds like an offer that I'm not going to want to refuse! Thank you. :)

Incidentally, I was a bit surprised when you said that only about 10 lb. could be saved on a 110 lb. frame if it were made out aluminium. I had expected it to be more. So I asked my metallurgist father if this were true.

He told me that aluminium would actually have better fatigue properties than does steel but that if it were built from similar strength aluminium tubing it would only be about 20 lbs. lighter than its steel equivalent. And of course, it would be much harder to work with.

So it could be done and there would be savings but you are right that the savings probably wouldn?t justify the effort.

He suggested titanium instead. :grin:

Stephen

cubunltd
06-10-2004, 05:44 PM
Lets not get into titanium. It requires welding in an inert atmosphere. If not welded properly it becomes very brittle. Oh by the way did I mention that I used to weld for the airlines (USAir). I'm certified to weld all those exotic metals, Titanium, inconel. hasteloy, magnesium. waspaloy etc etc.
Even if you had one welded in that type of an enviroment, where would you go to have tubing repairs done? The cost would probably be prohibitive also.
Hey the invite stands, There is no better place to learn about supercubs then where they are built and modified.
Just let me know when you 're coming.

John

Crash
06-10-2004, 10:22 PM
Fixed wing; Your question was a good one, and one I ask myself all the time when I'm assembling a Cub in my mind (awake and asleep) or in my hanger. I hate weight!! But I am also realistic when it comes to the final product and how I will use and enjoy it. The current Cub I just finished is the best flying Cub I have ever been in, but it came in at 1195 lbs dry (no oil or gas). I struggled with the thought of the extra weight of the O-360 180 hp verses the lighter O-320 160hp. I eventually let HP win out and really like the performance of the O-360. So you pick your poision and go with it. These planes are all a blast to fly. Take care. Crash

PA12driver
06-11-2004, 11:29 PM
Crash, So tell me how you like the Wings you built/bought for the 18 versus the ones on the 14? Was that a good choice?

Tim

Crash
06-12-2004, 01:32 AM
Tim, the wings on my PA-18 are new stock PA-18 Dakota Cub wings, my old wings were the original Piper wings that had extended everything mod with droop tips. I like the stock Dakotas a lot better. The PA-14 wings are basically the same thing except I bought a complete set of Dakota Cub ribs and put them on new Univair spars, leading edges, and false spars (Dakota didn't have theirs PMA'd at the time). I liked the way I did the PA-14 wings better because I was able to hang all the parts, primer them, then assemble the wings. The complete wing assemblies like I bought for the PA-18 are hard to spray all areas when they assembled. Take care. Crash

Steve Pierce
06-12-2004, 06:47 AM
Ditto that. I rebuilt a set of wings last winter but never took every rib off. Priming was a pain in the butt. The wings I am building now are down to nothing. It is a lot easier to prime everything and then assemble.

FixedWing
06-12-2004, 08:14 AM
So is there any chance that someone will take a shot at my original question? If nothing else, I'm still very curious where all of the weight goes on a Super Cub.

So what is the best guess at the various component weighs that make up a Super Cub?

Thank you.

Stephen

cobblemaster
06-12-2004, 05:09 PM
Original landing gear with hydrasorbs, 800X4 tires= 54lbs.

FixedWing
06-12-2004, 07:12 PM
Original landing gear with hydrasorbs, 800X4 tires= 54lbs.

Adds up quick doesn't it? I wouldn't think that the original landing gear would be so heavy.

Any guess what extended gear and tundra tyres add to this?

I would guess that the larger components, in decending order, are going to be the engine, the frame (110 lb.) and then the two wings. After that I would think it would be many components each adding a few pounds to the total.

Stephen

Kano
08-12-2004, 04:22 AM
Sorry, a bit late on the post...

A carbon seat was mentioned as a lighter alternative to steel. The catch is, when overstressed, steel deforms long before rupture, but carbon breaks. Actually, snaps. Better have my butt on a bendable item than on a bunch of potential splinters...

Philip

Fortysix12
08-12-2004, 07:53 AM
Are you going to look for horsepower as well. That's were I'd be spending time and money. More power and your plane gets lighter. How much do you weigh? And fuel. Flown your cub with only 2 hours of fuel on board? It's amazing the difference from full to 12 gallons. After reading your question I'm really not sure what your asking. Do you want to know what each component in you list weighs? Engine- light weight starter and altenator? Is that the kinda of your looking for.

CptKelly
08-12-2004, 08:48 AM
If one really wants a light plane, just fill the wing voids with plastic bags filled with helium, like they did with the big derigibles (sp?). Talk about slow landings and takeoffs.....

Mike

jr.hammack
08-12-2004, 01:41 PM
fixedwing,
currently rebuilding a pa-18A,going from basic stock to all light weight mods,alt.,starter,etc.,only problem i don't have a accurate scale to weigh the components on, will see if the scale i've got compare to others,if your interested.

jr.

FixedWing
08-12-2004, 09:57 PM
I haven?t looked at the Experimental Cubs section for a little while so sorry to all for not noticing that this thread has become active again.

I frankly regret that I ever asked this question. The question is far too ill defined and open ended. I was really only trying to get a basic idea of what the various parts that make up a Cub weigh so that I can get some sort of feel for what is important for weight savings and what is less so. Probably it would have made a lot more sense for me to wait until later and then to ask more specific questions.

Stephen

FixedWing
08-12-2004, 10:08 PM
A carbon seat was mentioned as a lighter alternative to steel. The catch is, when overstressed, steel deforms long before rupture, but carbon breaks. Actually, snaps. Better have my butt on a bendable item than on a bunch of potential splinters...

Maybe this topic deserves its own thread?

Philip, I'm not so sure you are right here. Yes, deformation is necessary to absorb the energy of a crash, but is the seat the best place for this deformation to take place? Look at the way a helicopter seat will channel the stress to the legs so as to spread the load over time. But I really don?t think you want the seat itself deforming.

I also don?t think that a carbon fibre seat will necessarily splinter. Look at what is done these days in Formula One. Those vehicles (including the seats) are absorbing a tremendous load without failure. No question that an aircraft pilot could realistically be put inside of a safety cell similar to what is now done in Formula One and that many more crashes would be survivable if this were done. But this is well beyond the expertise of any of us here.

Stephen

glassjet
08-13-2004, 02:58 AM
My uncle just rebuilt a cub... with all the goodies... light weight starter, alternator, battery, etc.... It does have 6 over gear with 26 inch bush wheels and a freshly overhauled 160 Horse...... It weighed in at 1103 lbs.. which we were happy with... I don't remember the exact number on the tail weight but it was about 45 lbs.. which put it right on the forward CG limit.... This thing really really performs.... I can't but wonder if the forward CG is almost as important as the light aircraft weight.... I'm looking for the same performance out of mine.... Any thoughts ? 8)