Page 2 of 7 FirstFirst 1234 ... LastLast
Results 41 to 80 of 244

Thread: New member building a PA18-95

  1. #41
    Lowrider
    Join Date
    Nov 2012
    Location
    Idaho Panhandle
    Posts
    1,682
    Post Thanks / Like
    Sky,

    I took your suggestion to move the hinges down seriously and have discussed it with my IA at length and we're going to come up with a plan to do that when I get started on the wings. He can't understand why there weren't flaps on there to begin with.

    Cub,

    I'm using 6" Matco triple puck 1.5" axle but my gear is upsized one tube size along with everything from the back of the door forward because of the 0-320. I have a C-170...does that mean I'm not Kool???
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  2. #42
    Cub junkie's Avatar
    Join Date
    Mar 2002
    Location
    My Moms basement
    Posts
    2,049
    Post Thanks / Like
    I edited my post so you are kool too. The reason there are no flaps on the LSA is for the very reason we all have discussed, Barrow is a lightweight freak. He had his reasons. You make a lot of reference to your IA as your engineering advisor. An Inspection authorization part of a maintenance certificate. Not saying your IA doesn't have some engineering ideas or maybe he has an engineering degree but when you make wholesale changes to a design you are in the dark without the help of an engineer. Thats why they call it experimental as we know but the major changes that have been done to cubs have all been looked at by engineers and tested to destruction by many.
    Last edited by Cub junkie; 05-09-2013 at 10:52 AM.

  3. #43
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    9,179
    Post Thanks / Like
    Lowrider,
    My suggestion of a Husky flap hinge was only as an illustration. Personally I hate that hinge as it is mandatory that you wear a crash helmet while anywhere near that wing.

    One thing to pay attention to is the shape of the trailing edge of the wing just ahead of the flap. It should flow smoothly from the bottom of the wing to the top of the flap/trailing edge junction. If it is not in a smooth lazy S shape it will generate turbulence over the top of the flap thus reducing good laminar flow over the flap. This means less lift. I used balsa wood to make a nice smooth shape on mine. It could be made from thin curved aluminum.

    Another thing is the width of the gap when the flaps are down. The gap will be greater when using the Husky hinge rather than the Piper hinge. I welcome input from an aerodynamicist here. I am of the opinion that the more narrow gap of the Piper, will generate a higher velocity flow over the top of the flap thus reducing/preventing flow separation on the top of the flap. This will result in more lift at lower speeds. If the gap is large with an angular wing trailing edge, there will be turbulence with a reduction of lift from the flaps. This will be evident with a reduction of stick back pressure at landing and stall speeds.

    This could get into a heated discussion of long Vs short flaps and their effect on pitch trim, so I will sign off for now.
    N1PA

  4. #44
    Lowrider
    Join Date
    Nov 2012
    Location
    Idaho Panhandle
    Posts
    1,682
    Post Thanks / Like
    Thanks Cub...I feel Kool now!!

    Totally agree with you about changes and that's why I am trying to follow tried and proven methods and incorporate them into my plane.


    Sky,

    Won't some version of a flap gap seal mitigate the over the top of the wing/flap flow?

    We should move back to my thread under "Lowrider LSA".

    Jim A, I'm sorry we hijacked your thread!!!
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  5. #45

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like

    Cub it shall be.

    I sheepishly called Bob from Bearhawk again last Friday and asked him if it was too late to cancel my plan order. Thank goodness for snail mail, checks, and understanding people. He hadn't received my letter yet and said cancelling my plan order would not be a problem at all. I felt horrible about making the call, but Bob was not upset in the least and we actually had a lengthy conversation about first time building and the pleasure of flying a Cub. I hope others help him fulfill his dream of seeing more Bearhawk LSAs in the sky.

    After reading everyone's replies to my thread and weighing my take on the pros/cons of a different design, I have come to this realization. I've spent enough time and money comparing plans. It's time for me to start building my Supercub. Why would I build anything else? Don't answer that, I need to stay focused. To keep me focused, I've created what I'm going to call "Jim's Building Code", JBC for short. Remind me of it if I seem to stray from course.

    Jim's Building Code

    1). I'm going to scratch build a mostly stock PA-18-95 with flaps.
    2). It will be built to operate primarily from wheels and skis with future floats in mind.
    3). I will involve my family in the build as much as I can.
    4). It will weigh 792lbs. or less when I am done.
    5). It's wing will have aluminum spars and ribs.
    6). It will be powered by a C-90.
    7). I will not compromise safety to make my target weight.
    8). I will scrutinize everything that goes into the aircraft and everything that I leave out.
    9). I will build it as inexpensively and as quickly as I can within a budget of $20,000-$30,000.
    10). I will fabricate as much of it as I can.
    11). I will log my hours, track spending, take photographs and document the build from start to finish.
    12). I will rely on others who have built before and/or are qualified to provide inspiration, information, and help with my build.
    13). I'm going to start on June 1st. 2013.
    14). I'm going to finish no sooner than June 1st. 2017 and no later than June 1st. 2020.
    15). I will need to spend on average 8-14hrs./week on the build in order to finish it within my time frame.
    16). Above all I will enjoy the building process and be happy with what is created in the end.

    Over the next few weeks I will be finishing up some projects that my wife would like to see completed before my family and I embark on this journey.

    Expect a new thread in "Member Projects In Progress" on June 1st!

    Thanks again,

    Jim Allen

  6. #46
    Bugs66's Avatar
    Join Date
    Feb 2004
    Location
    Spokane WA
    Posts
    2,309
    Post Thanks / Like
    Sounds like a good plan Jim! Here is some eye candy for motivation:
    http://www.bing.com/images/search?&q...rge&FORM=R5IR3

  7. #47
    Lowrider
    Join Date
    Nov 2012
    Location
    Idaho Panhandle
    Posts
    1,682
    Post Thanks / Like
    Jim,

    Looks like you have set goals and priorities that will get you a very nice airplane...more importantly, you'll enjoy the journey and by involving your family, it will be more meaningful when completed. Good luck on the build and I will be checking back on your list to make sure I haven't forgotten anything!!
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  8. #48

    Join Date
    Jun 2007
    Location
    New Zealand
    Posts
    486
    Post Thanks / Like
    Quote Originally Posted by Jim A. View Post
    I sheepishly called Bob from Bearhawk again last Friday and asked him if it was too late to cancel my plan order. Thank goodness for snail mail, checks, and understanding people. He hadn't received my letter yet and said cancelling my plan order would not be a problem at all. I felt horrible about making the call, but Bob was not upset in the least and we actually had a lengthy conversation about first time building and the pleasure of flying a Cub. I hope others help him fulfill his dream of seeing more Bearhawk LSAs in the sky.

    After reading everyone's replies to my thread and weighing my take on the pros/cons of a different design, I have come to this realization. I've spent enough time and money comparing plans. It's time for me to start building my Supercub. Why would I build anything else? Don't answer that, I need to stay focused. To keep me focused, I've created what I'm going to call "Jim's Building Code", JBC for short. Remind me of it if I seem to stray from course.

    Jim's Building Code

    1). I'm going to scratch build a mostly stock PA-18-95 with flaps.
    2). It will be built to operate primarily from wheels and skis with future floats in mind.
    3). I will involve my family in the build as much as I can.
    4). It will weigh 792lbs. or less when I am done.
    5). It's wing will have aluminum spars and ribs.
    6). It will be powered by a C-90.
    7). I will not compromise safety to make my target weight.
    . I will scrutinize everything that goes into the aircraft and everything that I leave out.
    9). I will build it as inexpensively and as quickly as I can within a budget of $20,000-$30,000.
    10). I will fabricate as much of it as I can.
    11). I will log my hours, track spending, take photographs and document the build from start to finish.
    12). I will rely on others who have built before and/or are qualified to provide inspiration, information, and help with my build.
    13). I'm going to start on June 1st. 2013.
    14). I'm going to finish no sooner than June 1st. 2017 and no later than June 1st. 2020.
    15). I will need to spend on average 8-14hrs./week on the build in order to finish it within my time frame.
    16). Above all I will enjoy the building process and be happy with what is created in the end.

    Over the next few weeks I will be finishing up some projects that my wife would like to see completed before my family and I embark on this journey.

    Expect a new thread in "Member Projects In Progress" on June 1st!

    Thanks again,

    Jim Allen
    Heck, I wish I could be as focussed as that!

  9. #49
    Bill Rusk's Avatar
    Join Date
    Jan 2003
    Location
    Spokane Felts Field, WA/Poplar Grove, (Chicago) IL
    Posts
    5,184
    Post Thanks / Like
    Jim

    Awesome. Gotta love a man with a plan.

    I look forward to following your build. You will have to fight yourself to hit the target weight. It is soooo easy to fall into the trap of......"it'll only add a little weight and it'll be worth it". Congratulations and good luck.

    Bill
    Very Blessed.

  10. #50
    Cub junkie's Avatar
    Join Date
    Mar 2002
    Location
    My Moms basement
    Posts
    2,049
    Post Thanks / Like
    Good choice on which airplane to build. You should build what you think you will want in the end result. Flaps on a light cub make sense and make a big difference. In choosing a cub clone if it comes to a time that you don't want to build a particular part you can buy it knowing it will fit and work. I'm going to remember that 792 goal. Bob Barrows responce is no surprise, long before he designed the Bearhawk line of aircraft he built a variety of different homebuilts. He is truly a homebuilder and his designs reflect what he has learned over the years.

  11. #51

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like

    Ribs

    If I buy a Carlson full rib for a pattern, will I be able to make a cut down version of it to make 3/4 ribs, butt ribs, tank ribs, nose ribs, etc? Or are the other ribs just enough different that I will need to buy more patterns to make them? This may be a question for Carlson. Another thought I had was to buy just the extruded T rail and make my own Piper truss style ribs from the Northland drawings. It looks like a guy could make the truss webs on his own, but an impossibility on the T. It also sounds like Carlson removes the bottom of the T to accomplish the bend at the leading edge and they don't do any shrinking on the top chord. Is this correct? I don't want to buy any more patterns than I have to and I don't want to get all screwed up using Carlson style ribs in the Northland drawings. I kind of like the idea of making Piper truss ribs because I have drawings of them that I could copy. It would take more time for sure. Safe? Possible to build? Too heavy because of the extruded T?

  12. #52
    Bill Rusk's Avatar
    Join Date
    Jan 2003
    Location
    Spokane Felts Field, WA/Poplar Grove, (Chicago) IL
    Posts
    5,184
    Post Thanks / Like
    Jim

    I hate to sound like a broken record but you can easily add 5 to 10 pounds to the total weight by using the wrong ribs. The original Piper Ribs were 6.8 oz. I do not know about Carlson but there are a lot of aftermarket ribs out there that weigh close to 13oz. It does not seem like a big deal until you multiply it by 26 or 32. If you are going to make your target weight you are going to have to watch every ounce. Don't start off by adding an unnecessary 10 pounds. Cub Crafters makes a light rib as does Javron. It will cost less to build your own and now you have an idea for a weight to shoot for. 1 oz on the rib will equal close to 2 pounds total. Just a suggestion.

    Hope this helps

    Bill
    Very Blessed.

  13. #53

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like
    Bill,

    I couldn't agree more. I want to build my own ribs. From what I understand, the Piper T doesn't exist anymore except on original ribs. As close to the original rib weight is what I'm after and I've heard that Carlson's ribs are the lightest out there but they are heavier and they are different. I' m just curious if I could build ribs like Piper truss ribs using the extruded T that is available, and not be heavier, preferably lighter than what the Carlson rib is.

  14. #54
    Cub junkie's Avatar
    Join Date
    Mar 2002
    Location
    My Moms basement
    Posts
    2,049
    Post Thanks / Like
    Carlson will sell you the rib capstrip extrusion already milled out for the nose rib radius almost as cheap as if you bought the material and did it yourself. As Bill pointed out, ribs are an area that gains weight fast. Carlson's ribs are pretty heavy when compared to a Piper. They seem to be a similar weight compared to a Dakota Cub rib.

  15. #55

    Join Date
    Jun 2007
    Location
    New Zealand
    Posts
    486
    Post Thanks / Like
    Jim,

    You can do what you describe, I am doing just that except I am using some stocks of Piper T-section and W-section that I have. I don't know what I will do when I run out; I have a few ideas, and using the Carlson T-section is one of them.

    Building Piper ribs is very fiddly and a real compromise and may not be what you want to do with your spare time. Because the Piper sections are not available if you use other sections or material you will tend to over-engineer it unless you do a structural analysis. Indeed anything you can fold up will not be as stiff as the Piper W-section pound for pound.

    Piper ribs are quite delicate and both the Dakota Cub and Univair ribs have been engineered to be more robust to stand up better in service. That advantage doesn't come free in the weight stakes of course.

    A trade off you will have to come to terms with is trading weight savings for dollars. Can I use this slightly heavier thingy and save myself fifty bucks. Or shall I spend the fifty bucks and save the weight. Ask Bill Rusk about his drilled brake discs!

    Cheers,
    Andrew.

  16. #56

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like

    Called Javron and Cub Crafters

    I made two phone calls today. I talked to Jay at Javron and Mitch at Cub Crafters. Their ribs are both 2-3oz. lighter than the Carlson rib. The problems are I won't be able to make them and to buy them seems to go against Bill's cost/weight breakeven suggestion. Man, they do look like nice ribs though. Jay and Mitch were very helpful and straightforward. I'm sure I'll be speaking with both of them again in the future. 4 to 5 pounds will be the weight cost in the ribs. I don't like it, but like Andrew said, I have to choose.

  17. #57
    Bugs66's Avatar
    Join Date
    Feb 2004
    Location
    Spokane WA
    Posts
    2,309
    Post Thanks / Like
    Has anyone weighed a D&E stamped rib? I wish I would have weighed one of mine. They sure seemed light to me but had nothing to compare to. All this talk of extreme weight saving wasn't around when I was building mine. I just put it together and have a nice flying Super Cub.

  18. #58
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    9,179
    Post Thanks / Like
    This is a bead roller. You can make dies of most any shape that will fit on it. If you have the desire to build your own ribs you could get some light weight sheet aluminum and make your own. These tools are available in many places for a reasonable price. I would think that you could make some ribs out of 0.016" 2024-T3 similar to Piper's, maybe with a "U" shaped cap strip. The curve could be formed using a shrinker or crimper. I'll not enter a sheet metal forming discussion here. It will be time consuming but satisfying and cost reducing in the end. You could calculate the weight in advance. 2024 aluminum weighs 0.101 lbs per cubic inch. This: http://www.onlinemetals.com/calculator.cfm is a calculator which may help.
    N1PA

  19. #59

    Join Date
    May 2010
    Posts
    1,334
    Post Thanks / Like

    Piper "T" section

    Click image for larger version. 

Name:	P1150824.JPG 
Views:	138 
Size:	752.3 KB 
ID:	11500

    This is my answer to the rib problem. Click on the picture until you get the + sign and then click once more for a large picture where you can see the detail of the T section close up. I ordered the main ribs from Dakota but manufactured my own "T" section for the "in between" nose ribs. Making the 24" t section was more a developed skill over several hours of trying out different ways to try and accomplish the goal. In the end the needed tools were a 3 in 1 (shear,brake,roll) machine, a modified bead roller (my own dies), A roller crimping machine, and a cheapy English wheel. After many failures I can now crank out 24" T section in under 10 minutes from .016" 6061-T3. I am not happy with the roller crimp (Chinese) dies I have so the final product is not exactly what I want yet but it will get there. I am doing this for fun and education (the reason for experimental)

    Click image for larger version. 

Name:	P1150827.JPG 
Views:	95 
Size:	704.0 KB 
ID:	11501

    Current box of shame. Those are mostly roofing flashing prototypes as is the properly bent structure in the first picture. The "T" section is 6061-T6 which is tougher to bend.
    Last edited by qsmx440; 05-17-2013 at 03:48 PM.

  20. #60
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    9,179
    Post Thanks / Like
    That looks great gsmx440. You seem to have the procedure down. Can you get 6061-T3? That should work easier.
    N1PA

  21. #61

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like
    This is great information guys. Good stuff to think about while fishing with my three boys this weekend. Better get ready. I'll check back on Sunday.


    Thanks,

    Jim

  22. #62

    Join Date
    Jun 2007
    Location
    New Zealand
    Posts
    486
    Post Thanks / Like
    Quote Originally Posted by Bugs66 View Post
    Has anyone weighed a D&E stamped rib? I wish I would have weighed one of mine. They sure seemed light to me but had nothing to compare to. All this talk of extreme weight saving wasn't around when I was building mine. I just put it together and have a nice flying Super Cub.
    Bugs,

    Did you rib stitch or pop rivet the fabric to the flanged D & E ribs?

    I haven't been keen on running the rib stitching past the edge on a flanged rib, so all the Univair ones I have used I've pop riveted for this reason. Just wondering what you did and what you think.

    For several years I ummed and ahhed about how realistic it was to build a Cub to fit into our microlight category, which until recently permitted only a 1200 lb max weight. The reality is unless you're totally focused on weight savings you won't have a good performing Cub with adequate payload when you're limited to 100 hp and 1320 lb max weight. I know what you mean though. If I put one of my kids in the back of my 150 hp Cub I can't tell the difference, so you wonder what all the fuss is about

    Andrew.

  23. #63

    Join Date
    May 2010
    Posts
    1,334
    Post Thanks / Like
    Quote Originally Posted by skywagon8a View Post
    That looks great gsmx440. You seem to have the procedure down. Can you get 6061-T3? That should work easier.
    Brain seize. To many projects
    Electric Renault Dauphine conversion, L21-150 horse (clone), ham projects,dogs, kids and fly's.. It is 6061-T3!

  24. #64
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    9,179
    Post Thanks / Like
    Using the calculator http://www.onlinemetals.com/calculator.cfm and making a wild guess as to how much material is in one rib, I'm guessing, that using 0.016" 6061-T3, one rib should weigh perhaps 9-10 ounces counting the rivets. That is assuming that the cap strip is 10' x 2" and the diagonals are about 5' x 1".

    How much does an original Piper rib weigh?
    N1PA

  25. #65
    Bugs66's Avatar
    Join Date
    Feb 2004
    Location
    Spokane WA
    Posts
    2,309
    Post Thanks / Like
    Yes I rib stitched. The flanges have a bevel so you can. Also the D&E wing does not have the half ribs like Piper. Less parts mean less weight.

  26. #66

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like

    Here we go.

    Ordered materials to start my build today. After looking into all the options available, decided to go with Carlson style ribs. I' m going to start with the left wing. I plan to build a squared off wing with 14 ribs. I bought one aileron rib to use as a pattern and 13 milled L-shaped capstrips. Before I ordered anything, I tried to make some T-shaped Piper style cap strip from aluminum flashing I had. I borrowed a bead roller and a shrinker/stretcher to play with. The best result I was able to make was with my brake and hand seamers followed by the shrinker/stretcher. I'm sure I could have eventually made the lighter Piper truss style ribs, but I'd have more money in custom dies and tools than I'd have in all the ribs. This didn't make sense to me at this stage. I'll be buying some tools that I don't already have along the way that I will for sure need. I hate to buy some now that won't for sure produce a creation I can trust or am happy with. I'm going to start building a fab table this weekend. Should have some materials and a rib to look at next week. Next step- build a rib jig and make all the left wing ribs. I'll look into moving this thread into the "Member Projects in Progress" category and post some pictures soon.

    Jim

  27. #67
    SpainCub's Avatar
    Join Date
    Feb 2009
    Posts
    612
    Post Thanks / Like
    Great Jim, I think we are eager to see your progress. BTW, why not blog it instead os starting a thread? I say this because every step (or post ) you add could be discussed separately with out interfering with the most current progress...

    Food for thought.

  28. #68
    Marty57's Avatar
    Join Date
    Jan 2005
    Location
    Nipomo, Ca
    Posts
    1,374
    Post Thanks / Like
    Jim,
    Best idea I came across was from EAA Ch. 1000 on building tables. http://www.eaa1000.av.org/technicl/w...l/worktabl.htm
    Their idea was to build three separate tables to be bolted together for the long table needed for the fuselage. After fuselage, they can be separated and used as needed. I went one step further and made mine three different widths. My 2+2 fuselage is pretty wide at the front so I made the first table just wider than that for the front. The table at the tail post didn't need to be as wide so I made it a bit narrower; middle table was in between. By doing that I didn't have as much far leaning and stretching when welding; saved an already messed up back further pain. I have used those three tables in every conceivable configuration over the years. Another tip I learned is when you strike the center line on the table. Chalk lines can be surprisingly off. In boat building I learned a nice trick. Paint your work table white after leveling. Stretch a heavy string (string line for foundations worked great for me) along the middle of the table as tight as you can. Get a can of grey primer and spray straight down over the string. When the primer is dry you have a perfectly straight White line down the center of the table outlined by the grey primer. Worked great for me.

    Marty57

    Click image for larger version. 

Name:	table.jpg 
Views:	57 
Size:	74.4 KB 
ID:	11654
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  29. #69
    Larry G's Avatar
    Join Date
    Nov 2010
    Location
    Minocqua WI
    Posts
    277
    Post Thanks / Like
    I like to use the white melimine on my table so you don't have to paint it. It's nice to use permanent sharpie on it then you can wipe it off with acetone.

  30. #70

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like
    Table is all but done. Two 3' tall x 3' wide x 8' long tables bolted together with full length storage shelf midway up underneath. If I need a third later, I still have room to build and bolt one on. My four year old and six year old boys helped with building the tables. The four year old learned a lesson about sawdust and rubbing your eyes and my six year old learned how to read a tape measure. You'd be suprised how many adults don't know how. Thanks Marty and Larry for your tips. Once I get a little closer to actually building something of length, I'll level everything up and refer back to your advice.

    Thanks,

    Jim

  31. #71
    Lowrider
    Join Date
    Nov 2012
    Location
    Idaho Panhandle
    Posts
    1,682
    Post Thanks / Like
    My lathe and mill are sitting on Melimine...easy to clean up!! Remember, at some point you are going to be welding on the table so I'm not sure how that will react to 6K degrees but I have had good sucess with using aluminum cookie sheets to put between the joint to be welded and the birch plywood I used. It does scorch some but a little sandpaper and white paint will fix that problem. I built 4' wide, two 8' tables and a 2' section between them all bolted together. I built a 2"x8" frame so it is pretty solid and I installed electrical boxes and compressed air outlets on the sides (8 of them) to keep the cord clutter to a minimum. Lag screws in the bottom of the legs allow you to level the table as needed and keep everything as it should be on the "bubble". Only other suggestion is make sure your tools and power equipment is close to your work to save time and walking...unless you need the exercise.
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  32. #72

    Join Date
    Apr 2013
    Location
    Cloquet, MN
    Posts
    135
    Post Thanks / Like

    Aileron/Flap questions

    While I'm waiting for materials, I've been thinking about flaps and ailerons and reading what others have said on different threads. I've also discussed privately with a builder what exactly he did. I'd like to hear what some other people have for opinions. I'm planning to run flap and aileron from the fuselage to the square tip of my wing. If I'm not missing something, the length will be 16' with the rear spar being the limiting factor. Because of weight and because of C90 engine, I'm planning 14 aileron ribs that I will make from Carlson L capstrip and a pattern aileron rib. The L is slightly lighter than their T. I'm planning on having an engineer buddy or two take a look at the Carlson aileron rib and advise on different intercostal shapes/lightening holes to make it as light as I can and still be safe. The wing I envision is a standard 13 rib with an aileron rib in place of the wing tip rib and a 14th aileron rib on the end of the rear spar. Not knowing much, but sounding like a good idea is making the leading edge from carbon fiber and doing away with all the nose ribs to save more weight. I also like the thought of adjustable droop ailerons. If I understand, one could dial them up for better cruise and dial them down for better slow flight. I'm not sure on wing tips yet, but again I am pondering making my own from carbon fiber or possibly leaving them off entirely. From what I can gather from the prints, it looks like a standard aileron is roughly 102.125 inches and a standard flap is roughly 62.5 inches. It also looks like the standard chord length for both flap and aileron is 13.25 inches. If I do what I plan, it looks like I'll have roughly 25.25" to fill in with either aileron,flap, or a combination of both.

    Here are the burning questions...

    How long for the aileron?
    How long for the flap?
    Should I go with the standard chord for flap and aileron? I'd like to because of weight and simplicity but again, I don't know much.
    What about lightening holes in the spars like the CC? This one scares me. Maybe it shouldn't.
    Should I worry about twisting spars with 14 ribs and longer aileron/flaps?

    Keep in mind C90 engine, primarily wheels/ski's with possibility of future floats. 792 pounds. Not a STOL competitor but want to hop off the ground and land/fly slowly with control. I am going to shy away from LE slats/slots in favor of a little more cruise speed. I want to build the toughest, lightest wing I can and not worry about tearing it off.

    Thanks,

    Jim

  33. #73
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    9,179
    Post Thanks / Like
    Quote Originally Posted by Jim A. View Post
    ...I'm planning to run flap and aileron from the fuselage to the square tip of my wing. If I'm not missing something, the length will be 16' with the rear spar being the limiting factor. Because of weight and because of C90 engine, The wing I envision is a standard 13 rib with an aileron rib in place of the wing tip rib and a 14th aileron rib on the end of the rear spar.
    Place a full sized rib at the tip. This will give you an attachment for the squared off removable tip.

    Quote Originally Posted by Jim A. View Post
    Not knowing much, but sounding like a good idea is making the leading edge from carbon fiber and doing away with all the nose ribs to save more weight.
    You still will need to address the air load on the leading edge which is trying to collapse it. This is the main reason for the nose ribs.
    Quote Originally Posted by Jim A. View Post
    I also like the thought of adjustable droop ailerons. If I understand, one could dial them up for better cruise and dial them down for better slow flight.
    I like drooping ailerons. I have flown them on a Cub. They do help take off and landing performance. The Cub, which I have flown, had them connected through a complicated movable pulley system to the flap handle (weight). Drooping aileron systems reduce the up aileron travel which is important in crosswinds. The question of up for higher cruise only works on certain airfoil shapes. I doubt that the Cub is one of those. I rigged the drooping ailerons on my 185 so that I could test this theory by varying their position while in flight. Any position other than neutral, slowed down the cruise speed.

    Quote Originally Posted by Jim A. View Post
    I'm not sure on wing tips yet, but again I am pondering making my own from carbon fiber or possibly leaving them off entirely.
    Mine are squared and slightly drooped. Screwed on to the tip rib. They will have less drag if they are most any shape other than "just left off".

    Quote Originally Posted by Jim A. View Post
    From what I can gather from the prints, it looks like a standard aileron is roughly 102.125 inches and a standard flap is roughly 62.5 inches. It also looks like the standard chord length for both flap and aileron is 13.25 inches. If I do what I plan, it looks like I'll have roughly 25.25" to fill in with either aileron,flap, or a combination of both.

    Here are the burning questions...

    How long for the aileron?
    Mine is 88" with the control horn at the inboard hinge location.
    Quote Originally Posted by Jim A. View Post
    How long for the flap?
    Mine is 110" starting at the fuselage.
    Quote Originally Posted by Jim A. View Post
    Should I go with the standard chord for flap and aileron? I'd like to because of weight and simplicity but again, I don't know much.
    Mine is standard chord.


    Quote Originally Posted by Jim A. View Post
    Keep in mind C90 engine, primarily wheels/ski's with possibility of future floats. 792 pounds. Not a STOL competitor but want to hop off the ground and land/fly slowly with control. I am going to shy away from LE slats/slots in favor of a little more cruise speed. I want to build the toughest, lightest wing I can and not worry about tearing it off.

    Thanks,

    Jim
    792 pounds is a lofty goal. Good luck.

    LE slats/slots require a lot of power to over come the drag when operating them at their maximum effort/effect.

    In my opinion long flaps when used at the proper angles are very effective. Testing will tell you which angles are best for your application. My Cub "floats" with full flaps. I wish that I could get a lot more deflection comfortably. The reason that I can not is two fold. My flap handle is not long enough to provide the force necessary. And the handle location is too far aft behind my range of motion to be able to effectively operate. Currently my best take off position, for short distance and angle of climb, is the full 50 degrees. However, because of the awkward use of the flap handle close to the stall speed, I do not consider it to be safe.
    N1PA

  34. #74
    Bill Rusk's Avatar
    Join Date
    Jan 2003
    Location
    Spokane Felts Field, WA/Poplar Grove, (Chicago) IL
    Posts
    5,184
    Post Thanks / Like
    Jim

    That is a lot of ground to cover. A lot of that info is on the site here and can be found with the search engine.

    Here are my short answers


    How long for the aileron? Std aileron but moved out to the tip
    How long for the flap? Build to take up all the room from moving the aileron outboard
    Should I go with the standard chord for flap and aileron? Yes, weight will be everything with a 90Hp engine I'd like to because of weight and simplicity but again, I don't know much.
    What about lightening holes in the spars like the CC? You will need to to keep it light This one scares me. Maybe it shouldn't.
    Should I worry about twisting spars with 14 ribs and longer aileron/flaps? Probably not. A 90Hp Cub will be slower and generally have less air loads than a 180Hp Cub


    You do not have the power to carry the extra weight and area of the square tipped wing. Go round tip and keep it as light as possible. You do not have the power to carry the increased weight of a droop flap/aileron system.

    You will never make 792 pounds with your current mentality. I am not trying to be rude or harsh but you are going to have to give up a LOT of stuff to make your goal weight. If you do make that weight you will not need the other things (droops, Sq tips, flaps, Etc). You are trying to build a Jerry Burr Cub. He has won short field contests all over the place, not because of all the mods but because he has a very light Cub (and he is a VERY good stick). A light Cub is a wonderful thing to fly. What you sacrifice is utility. You will not have the range, or load hauling, capability of a larger engine, heavier Supercub. If you do all the things you are talking about above you are going to have a 900 or 950 pd Cub and with a 90hp engine it will not perform like you want. It is all about trade offs. You are still trying to build a light cub but do not yet understand what that means. Search weight and cub on this site. Jerry Burr is your standard. Talk to him. Read his posts. Just about every "improvement" you are thinking about adds weight. You can't do that.
    You need to have a gram scale by your side even when you sleep.

    My recommendation. Start collecting used wing (J-3/PA-11, early SC) parts off Ebay or Alaska list until you have enough parts to rebuild/build up a set of basically J-3 wings. Nothing is lighter than the original factory rib, just keep collecting until you have a complete set of useable ribs. Drill the spars. Use CF leading edges but leave the nose rib in. Add the two 11 gal wing tanks. (oops just added weight, even offset by drilling the spars and CF LE, will still add 5 to 10 pounds) No flap, round tip, no landing lights, 13 rib, fabric cover over the wing tanks, primer only where necessary,.......

    Just trying to help

    Bill
    Very Blessed.

  35. #75
    Bugs66's Avatar
    Join Date
    Feb 2004
    Location
    Spokane WA
    Posts
    2,309
    Post Thanks / Like
    I agree with what Bill said. Also ditch the droop ailerons for sure.

    I have said it before, if you want to build a kite, then go for it but don't expect it to be much stronger, capable, or durable than a kite. My main point is folks seem to sacrifice so much then after the plane is completed and flown wish they had a more capable or durable aircraft.
    Last edited by Bugs66; 06-06-2013 at 11:48 AM.

  36. #76
    Cub junkie's Avatar
    Join Date
    Mar 2002
    Location
    My Moms basement
    Posts
    2,049
    Post Thanks / Like
    Some J-3 rebuilds get close to your target weight with heavy finish and add ons. If you want to get good performance from a C-90 build an experimental J-3 with a PA 11 style back seat and a SC elevator system so you can have a standard PA18 baggage which is enough. Building an airplane is a daunting task and if you don't have a plan in the begining then changing your mind midstream will add time and weight. As mentioned, Jerry Burr is the king of lightweight continental powered cubs. I would look for pics of his ship and study what you can find out from them.

  37. #77

    Join Date
    Jun 2007
    Location
    New Zealand
    Posts
    486
    Post Thanks / Like
    Jim,

    I kinda echo the same thoughts as the other respondents to your last post. I said earlier something like if you want a Cub, build a Cub and if want something different, build something different. I know this is going to sound rude, but the plane you describe is not a PA-18-95. With longer chord flaps and ailerons, extended wings and flaps and modernised structures (carbon fibre), you might be better off building that Bearhawk Patrol, because Bob Barrows has done just that, incorporated a lot of modern ideas and new technology into the basic Cub format.

    I am attempting to build a Cub to fit into the New Zealand microlight category. Until recently I only had a 1200 max. weight to play with. It is now 1322 lbs, and while there are differences between our microlight rules and the US LSA rules, as far as a Cub goes they are pretty much the same. This is something I have been mulling over for some years now and I have spent a lot of time taking upon ideas, evaluating them, re-evaluating them and then rejecting or accepting them. For all sorts of reasons I am not building a PA-18-95 clone, but I will be using as many stock Piper parts as I can. I really think you have a lot of thinking to do if you are going to depart from the tried and true PA-18-95.

    Because I am attempting a low power experimental Cub, I can see that the perspective of the guys who have posted is from their experience with their 180 hp machines. There are a few guys who post on this forum (Tempdoug, SuperXP11 and one or two others) who have built 90 hp experimental Cubs. I would get hold of them or read their posts and see if their Cubs are what you would like. SuperXP11's machine is sub-800 lbs and has squared off wings I believe, but Doug's is over 900 lbs I seem to recall. These guys are doing it, with flying planes. If their machine is what appeals to you, that is probably what you have to aim for. If it is not, you are then going to have to add and subtract a few things.

    All the best,
    Andrew.

  38. #78
    Lowrider
    Join Date
    Nov 2012
    Location
    Idaho Panhandle
    Posts
    1,682
    Post Thanks / Like
    I'm doing a lot of the same things Jim is looking at and I continue to rethink the flaps because of weight but I'm going with a 0-320 for sure because of density altitude where I"ll be flying. Flaps provide significant benefits in my opinion and I think that is shared by a lot of you folks. I've beefed up the fuselage for the 0-320 and will be starting my wings soon so I need to make decisions and live with them. I want simple and as light as possible while still giving me the features that I believe are necessary for my mission and probably floats in the future. Keeping it light to stay inside LSA weight and still make it tough enough to handle rough field work is a big challenge!!
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

    There are no new ways to crash an airplane no matter how hard you may try!

  39. #79

    Join Date
    Sep 2002
    Posts
    1,621
    Post Thanks / Like
    Were it me, I'd forego the 90 and run an O-200 with 9.5 pistons for an extra 10% power and torque. Combine with a Mac 7535 for takeoff and climb. Does great climbing at 55 mph and 2850 rpm.

  40. #80
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    9,765
    Post Thanks / Like
    Quote Originally Posted by JimC View Post
    Were it me, I'd forego the 90 and run an O-200 with 9.5 pistons for an extra 10% power and torque. Combine with a Mac 7535 for takeoff and climb. Does great climbing at 55 mph and 2850 rpm.
    If your going to over prop it and lug it around then a C90 is what you want. But if you let a 0200 breathe above 2700 it will make the hp you need. Does great climbing at 45. Jim understands the math, I just remember the smile.

    Glenn

Similar Threads

  1. New member
    By willirw in forum Cafe Supercub
    Replies: 6
    Last Post: 02-16-2010, 06:17 PM
  2. model change PA18-125 to a PA18-150
    By cubcrasher in forum Modifications
    Replies: 5
    Last Post: 02-23-2005, 03:03 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •