bigtj10

My Feedback: (1)

I have a Sig Senior, the first airplane I built and flew as a trainer. Now I would like to build a wing that has ailerons and reduce the dihedral to something closer to normal than the dihedral in the original wing.?

JohnBuckner

My Feedback: (1)

Tom First I have been a major booster of Senior Cadets for a long time and I have built a fair number of diverse Kit bashes and currently have five flying. They include: a standard trainer with ailerons and powered with an OS AX .35, its a working airplane and flew this one today. A four engine version with four OS .25FX, its been very successful for almost 19 years now. A single float cross country Cadet with a gallon of fuel, extended wing and area that has had a static flight of just over 6 hours. A twin engine version that is a chameleon and in minutes the engines are dropped off and the glider version is aerotowed into the air by another airplane. Lets see one more a giant version and greatly enlarged version on floats around 98 inchs or so. This wonderful old bird was gifted to me from a friend and is about 25 years old. Just one more that is well under the way and currently on the table is bi-powered one OS 55AX/one Graupner T-500 turbine. Also bi- controlled will be flown both controlline and RC.

OK got all that out of way and back to your question, I have found the fellows and myself are happiest when adding ailerons to a Senior with roughly one half of the indicated stock dihedral of the kit version. In other words the stock is six inchs at one tip and anywhere around three inchs at one tip is perfect!

Definitely avoid totally flat. If you really want to get wild add about the same amount of drop at the tips as most would use in dihedral . In other use words use about the about three inchs of drop (anhedral) instead of dihedral. this will provide an almost totally neutral roll response as possible and a magnificient aerobat. Seldom ever done as most don,t have the courage those that do are quite surprised in a good way.

John

Top_Gunn

My Feedback: (6)

Yup. I've only got one, though. Built a new wing with about half the dihedral of the original and large barn-door ailerons, and it flies very well. If I ever finish my current project I plan to build another with a low wing. For that one, though, the stock dihedral looks about right to me.

I don't think the exact amount of dihedral matters much. A guy in my club just added strip ailerons to a stock Kadet Senior wing and it flew very well.

Jason Gross

Way ahead of you Top Gunn ! I can't wait to get mine in the air as it's my first build. I've been waffling between barn door or big strip ailerons. One of the flyers at our field has one with reduced dihedral and 1 1/4" strip ailerons and it seems to fly real nice but, on the other hand I've done so much "extra" work already that it kind of feels like I'd be cheating by going with strips...

JohnBuckner

My Feedback: (1)

Hey Jason your low winger is looking good Here are some photos of a member who has passed on and his low winger, don,t know if you ever saw the two he built.

I did do strip ailerons on one about eighteen years ago and about 1 or 1 and a quarter and while it worked ok and of course very smooth the roll response was very poor and always took a lot of help from the rudder. It was a high wing ship though.

John

JohnBuckner

My Feedback: (1)

Hey Jason your low winger is looking good Here are some photos of a member who has passed on and his low winger, don,t know if you ever saw the two he built.

I did do strip ailerons on one about eighteen years ago and about 1 or 1 and a quarter and while it worked ok and of course very smooth the roll response was very poor and always took a lot of help from the rudder. It was a high wing ship though.

John

JohnBuckner

My Feedback: (1)

sorry guys somehow trying to get that pic of my fat butt outa there I only ended up in another double post

Rodney

I have built the Sig with perfectly flat wings and barn door ailerons. Excellent results, still ultra stable but can do rather fast rolls if commanded. The only thing one might not like about a flat wing, it can appear to have anhedral in some views. Performance wise, still excellent with the flat wing.

JohnBuckner

My Feedback: (1)

Speaking of anhedral For any high wing cabin type of airplane its my belief that considerable anhedral will get the airplane far closer to that elusive and fabled total 'neutral roll stability' It will make any 'high wing cabin type' a totally different and pleasant experience.

Although I have not done this with a Senior Cadet Yet, I have built/bashed four generic trainers with anhedral wings over the years and all have been very successful and the fellows just had to have them. It was hard for me to hang onto them. The last one I did about four years ago and I called it the Taxi Dancer, I think the starting point was an Aerostar 40 trainer. Will get some pictures up .

The wing were already in one peace and they were literally hack sawed in two the the sheeting cut away and new doublers were clamped on front and rear at the new angles.

Yup this has got me motivated a little and I think soon after the current project I will do another anhedral wing this time for a Senior and I think I will us about four inch droop at each tip. Probably will set it up as a second wing for the standard on my 35AX working trainer, That little AX is so awesome on a Cadet that have been kept light.


John

stevegauth30

http://www.rcuniverse.com/forum/kit-...ior-sport.html

Check this build thread. Tom is a great builder and just finished up his kit built senior sport. He built ailerons and flaps along with many other mods.

Top_Gunn

My Feedback: (6)

Yeah, don't remember where I saw it but people who know more about aerodynamics than I do have said that anhedral is best for high-wing planes, dihedral for low wing planes, and a straight wing for mid-wing planes, if the goal is neutrality. That's one of the reasons I'm not going to reduce the dihedral from stock when I do a low-wing Kadet Senior with ailerons. (The other reason is looks: a lot of low-wing planes, especially golden-age, have a bundle of dihedral.)

stevegauth30

Really? Anhedral for high wingers? I thought dihedral added stability. Like the old free flight planes with tons of dihedral. I have to admit, I have a lot to learn in the aerodynamic arena.

Top_Gunn

My Feedback: (6)

Dihedral does add stability. But there are other goals. like continuing to go where you point it, and reducing coupling. A Kadet Senior is so stable anyway that you can easily give up some. And the reason the stock wing has so much dihedral is that it's a three-channel plane, so you want it to roll when you apply rudder. With four channels, you don't need that.

JohnBuckner

My Feedback: (1)

The idea steve with the high wing cabin type is to completely remove all the self righting effects of dihedral so that roll response is completely neutral. This is that elusive stays where you put literally tendency and what Al Gunn posted above about dihedral is quite right. A totally flat wing on on a low winger moves away from that neutral point. For a low wing to acheve that neutral some degree of dihedral or dihedral effect is necessary and of course a midwing with a flat wing is already close to the neural point.

Yes Al gunn I you are quite right about the low wingers. That gentlemans picture of his low winger I posted above worked out very well but he had built one before that with a flat wing. I had done the initial test flying on both and the flat wing original was terrible being unable to stabilize in level flight constantly falling off in both directions. The second ships with three inchs dihedral each side at the tips made all the difference in the world and become a very pleasant flyer. That ship has even piggy backed 118 inch eight pounds gliders quite stabile and a pleasant roll response.

John

Rodney

+1 again John, as usual your comments are right on. I've done similar experiments with high wing planes with the same results.

stevegauth30

Thanks guys for the clarification. It makes perfect sense when put like that.

MARK JR

John do you have pics of your cross country kadet

bigtj10

My Feedback: (1)

Do you have any photos of how to build ailerons for the Sig Senior wing? I kind of dropped the ball on building the wing and went on to other planes but now I want to build the wing with less dihedral and add ailerons; I seem to remember seeing a photo of a wing with ailerons posted on this forum but I can't seem to navigate this forum without getting lost; I don't know if you are still posting on RC Universe even but I like your answers and I am almost certain you could help mefind the answers I need.

bigtj10

My Feedback: (1)

Do you have any photos of how to make ailerons or the "barn door" flaps I keep hearing about?

bigtj10

My Feedback: (1)

Dol you have any pictures of how to make ailerons for the Sig Senior wqing?

Top_Gunn

My Feedback: (6)

No pictures of how to make them, but here are a couple of shots of the bottom of one of my barn-door ailerons on a Kadet Senior, deflected fully upward so as to show more of the arrangement. The ailerons are hinged at the top, near the upper edge of the rear spar. The aileron itself just matches what would have been the chunk of the wing that you have to do without to make room for it except that the bottom of the forward side has to be slanted some so it can deflect downward. I've done this twice: Once by building a wing that way and once by starting with an already-built kit wing with no ailerons, cutting out part of it to make room for the ailerons, and making ailerons to fit. Hope this helps.

bigtj10

My Feedback: (1)

Thanks very much!!

ETpilot

This may help. Ailerons
Not too difficult a task. I put barn door on my LT-40.

Top_Gunn

My Feedback: (6)

Really wish I'd put flaps on one of mine. Doesn't need them at all, but they are seriously cool.

bigtj10

My Feedback: (1)

That anhedral drop is way fascinating!! I feel like such a stick in the mud having never had the early experiences and gained confidence in experimenting with all phases of this small airplane science!! Thanks for your fascinating ideas; I better order another wing replacement set for this Sig SR. Maybe it is time to figure out how to change the anhedral/dihedral of the wings with some kind of mechanical solution? Surely you have had some thoughts about it?? Thanks for opening my eyes!!
Tom