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Thread: Cool New Flaps on the way? Decent Article with Pictures on the Planes at Valdez

  1. #41
    jgerard's Avatar
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    Bill the Micro VG's were there when you, me, and DW flew it last weekend. Wing only, and CC gap seals on the tail. I agree that this is going to be a nice improvement to a Supercub and look forward to flying it again soon to further explore the parameters.

    Jason

  2. #42

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    I keep getting asked how much this mod will cost and I am reluctant to throw out a number, there are lots of obstacles to cross yet and it is impossible to predict at this point. I can tell you that my goal is to be able to offer it certified for under $5,000. I will work hard to certify it and make this happen, but I cannot make any promises.
    Doug
    Last edited by ksecub; 05-18-2011 at 09:26 PM.

  3. #43
    Dave Calkins's Avatar
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    Bill, thanks for your compliment.

    Doug, don't make any promises. 5K for what is reported to be a very usable performance increase is HIGH VALUE, in my opinion.

    (Some will dis-agree, thinking 5K is alot of money for "just" Keller Flaps...........right after 5500 dollars is spent on the cool factor of tires).

  4. #44
    Gunny's Avatar
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    Curious if there is any thinking on performance improvement conflict between slots/slats and the proposed flaps? Would flatter deck angle detract from slot/slat performance? Probably too early to tell at this point. Sounds like a great project!!
    "You are the Gray Rider who would not make peace with the Blue Coats, you may go in Peace." - Ten Bears

    Gunny

  5. #45
    Steve Pierce's Avatar
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    Quote Originally Posted by Gunny View Post
    Would flatter deck angle detract from slot/slat performance?
    I thought the same thing Gunny and figured it wouldn't be a good mod on a slotted or slatted wing.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  6. #46
    skywagon8a's Avatar
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    Using both slats & Doug's flaps could open a large can of worms in the certification process. A greatly lower stall speed could require new tail surfaces. The flight tests could turn up other required alterations. His best/safest move would be to certify the flaps on a stock PA-18. After that???? and more$$$$.
    N1PA

  7. #47
    Dano Bardwell's Avatar
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    So Doug, how does one sign up for a set of NON certified
    Flaps that you want to build I'm very enterested !

  8. #48

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    Flap update. I had another DER test pilot fly the airplane yesterday and I got the same report as the first DER test pilot. I have to fix the tail separation before the flap is certifiable. The flaps are basically too powerful for the existing tail. Ideally we will come up with a bolt on fix like a strake, VGs, or some other device which will be easy and quick to add to the airplane. If we cannot come up with a bolt on device I will try a new horizontal stabilizer. I built a set of stabilizers that use a NACA 0012 airfoil on the bottom surface only. The stabilizers look just like the original ones but have an airfoil on the bottom side only. I need to cover these and try them out. I need to do some more tufting and video work under the existing tail to see if there are any clues to help solve the problem. Bottom line is, just adding the flaps alone is not certifiable.
    Regarding the Experimental market, I personally like the airplane just the way it is, the stick shake does not bother me and I would fly it this way for the rest of my life. I donít know if I feel comfortable with people flying it without fixing the problem or at least investigating it further. I need a little more time to get to the root of the problem before I hand them out to the experimental market, I donít want any widows suing me, itís just not worth anyone getting hurt over.
    The problem can be solved or at least the flaps can be determined safe or not with some more time and effort, until then I think we will have to be patient. Thanks for all the support and encouragement.
    Doug

  9. #49
    Steve's Aircraft (Brian)'s Avatar
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    Doug,

    Earlier it is stated that the flaps are extended inboard to the fuselage.... I know that on our Pacer with the stock flaps extended inboard that there is some buffeting of the tail surfaces that was not there before the modification....Perhaps this is the same with your flaps...I know it would probably take a lot to modify them at this point, but you might want to consider making them the stock cub length and try them before you make any more major modifications to the rest of the airplane.....

    Also on the Pacer note....any chance you might make them for the PA-22 / 20 also..??

    Brian.

  10. #50
    Dave Calkins's Avatar
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    Quote Originally Posted by Steve's Aircraft (Brian) View Post
    Doug,

    Earlier it is stated that the flaps are extended inboard to the fuselage.... I know that on our Pacer with the stock flaps extended inboard that there is some buffeting of the tail surfaces that was not there before the modification....Perhaps this is the same with your flaps...I know it would probably take a lot to modify them at this point, but you might want to consider making them the stock cub length and try them before you make any more major modifications to the rest of the airplane.....

    Also on the Pacer note....any chance you might make them for the PA-22 / 20 also..??

    Brian.
    Very good point. Definitely worth a look at the point Brian makes before doing a whole lot of other work to eliminate the shake.

    Also, where was the CG for the test flights?........thinking that an aft CG would minimize the shake if it's due to separation from a "stalled" condition of the stab. Versus a 'washing' of the stab by the flap flow.

    ...wish I'd taken the time to fly it. D

  11. #51
    skywagon8a's Avatar
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    IF it turns out that changing the airfoil on the stab solves the problem, it would be relatively easy to just glue a wood fairing on each rib or rivet or screw a new rib to the original rib. A whole new stab would not necessarily be required.
    N1PA

  12. #52
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by skywagon8a View Post
    IF it turns out that changing the airfoil on the stab solves the problem, it would be relatively easy to just glue a wood fairing on each rib or rivet or screw a new rib to the original rib. A whole new stab would not necessarily be required.
    one piece kydex bottom, held pop rivets

  13. #53

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    Quote Originally Posted by Steve's Aircraft (Brian) View Post
    Doug,

    Earlier it is stated that the flaps are extended inboard to the fuselage.... I know that on our Pacer with the stock flaps extended inboard that there is some buffeting of the tail surfaces that was not there before the modification....Perhaps this is the same with your flaps...I know it would probably take a lot to modify them at this point, but you might want to consider making them the stock cub length and try them before you make any more major modifications to the rest of the airplane.....

    Also on the Pacer note....any chance you might make them for the PA-22 / 20 also..??

    Brian.

    Please! This would be a great mod for a Pacer.

  14. #54

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    I am still working on FAA, STC approval. The stumbling block is still the stick shake.

    The DER test pilot flew the prototype again today and really likes the way the plane flies, but it is still not certifiable in his opinion, due to the stick shake. He said that he would put it on his experimental cub and really thinks it makes a difference in performance. The flap system has been tested by many pilots and no one has had a problem with the stick shake expect the DER test pilot and he said it was just from a certification point of view. I am now under the impression that a new horizontal stabilizer may be needed to pass certification. If I had an experimental Cub I would not change the tail and would not think twice about it. A new horizontal stabilizer with add complexity and cost, I am satisfied with its current flight characteristics, unfortunately it does not meet a couple a flight test requirements which in my opinion are not a function of safety. I am not saying that the rules are not valid or worthy, they are, they just might be a little too stringent in some cases.

    I have been asked to provide the flap system for the experimental market but have been reluctant to do so with the stick shake issue. After extensive testing and talking to DER test pilots I do not feel that the stick shake poses a safety concern and therefore plan to release it to the experimental market at the Johnson Creek fly in this weekend.

    I will have pricing and availability at that time. Ideally I would like all perspective buyers to fly the airplane prior to their purchase so they can see the added performance as well as the minor stick shake prior to making the decision to purchase. Unfortunately the prototype aircraft is not insured so I need to be careful letting people take it around the patch. I would insure it, but the aircraft is now in experimental market survey category and think it would be unlikely that an insurance company would be willing to under write a policy for me. Up to this point I have only let pilots I know or know of fly the airplane, I will need to think about how to handle letting people I donít know test fly the aircraft. Any suggestions would be greatly appreciated. Perhaps I could fly in the back seat and be PIC. Maybe I could get people to agree to return it to me in the same condition I lent it to them, or if they crash it, pay for the rebuild.

    Any way I look forward talking about it and getting people to fly the prototype at Johnson Creek or here in Portland.

    Thanks,
    Doug

  15. #55
    www.SkupTech.com mike mcs repair's Avatar
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    just a thought or two...

    can you stiffen the elevator 'feel' some to lessen the shake making it to the stick, i.e. tighten the stick stubs cross bolt(s) in yoke some/add rubber washer(s), and loosen? elevator cable tension some(or tighten?), to lessen the shake transmission to the stick???

    or play with the elevator bungee cable length(shorten) to use bungee to soak up(change frequency?) some of the vibration??

  16. #56
    aktango58's Avatar
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    maybe avoid letting anyone from a state called Okla-Homa

    or one wearing a blue hat that says flip or flop

    or just demonstrate from the back seat when close to the ground. I would love to see it fly, but am certified...
    I don't know where you've been me lad, but I see you won first Prize!

  17. #57
    skywagon8a's Avatar
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    This project has my juices flowing. The idea of improving the performance of an airplane fascinates me. I am trying to do the flight testing in my mind, here on the east coast.

    Can you be more specific as to exactly what the tail shake is? Is the stabilizer shaking? The elevator? Or both? Does it do it with power on or at idle? Or both? Did it make any difference changing the cable tension? At how much speed above the stall does it start? What happens at a lesser degree of flap deflection?

    Changing the airfoil on the bottom of the stabilizer only would likely change the trim throughout the entire flight envelope. It seems to me that if you were to change the stabilizer airfoil that it should be done symmetrically.

    As Brian suggests that perhaps the shake comes from extending the flaps inboard as the cause of the shake, would installing a fence on the inboard end of the flap have any effect?

    This is just me thinking out loud. Perhaps you have already thought of all of the above.

    Keep it up. Thank you for keeping us in the loop.
    N1PA

  18. #58
    StewartB
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    Does the tail shake when the flaps aren't fully deployed? Perhaps limit the travel for certified planes. If the pilot/owner removes the limiter???? Or is there a load or gear configuration where the tail shake is diminished? Lots of Cessnas are factory equipped with 40* flap settings yet are limited (by placard) to 30* on floats. I bet some guys disregard the placard.

    Certification is probably tougher now. It looks like a great mod. Good luck making it a successful venture.

    Stewart

  19. #59
    Dave Calkins's Avatar
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    Doug, did you tuft test the fuselage to see where the flap-"wash" is directed? Still curious about that.

    I think Mike has a great idea with 'tightening' the elevator control system.

    ....sure wish I'd flown it here while I had the chance. A very cool mod!!

  20. #60
    behindpropellers's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    just a thought or two...

    can you stiffen the elevator 'feel' some to lessen the shake making it to the stick, i.e. tighten the stick stubs cross bolt(s) in yoke some/add rubber washer(s), and loosen? elevator cable tension some(or tighten?), to lessen the shake transmission to the stick???

    or play with the elevator bungee cable length(shorten) to use bungee to soak up(change frequency?) some of the vibration??
    If the air is turbulent....causing the stick to shake you need to fix that problem, not put a band aide on it. Besides.....doing anything with the control system would add more engineering to the problem (control system change).

  21. #61
    jgerard's Avatar
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    I was told that the flap restriction on Cessna's has to do with full power go around certification requirements, based on the FAA acceptable standards of stick force at a particular trim setting and C/G - bla bla bla bla ( you get the picture ) It's all in the regs and anyone can look up certification flight test standards and parameters.

    When I flew the plane It seemed to be both from what I could see and what I felt that the shake is all in the elevator. Doug and I talked about increasing the top and bottom bungee system tension on the elevator to reduce the elevator flutter and increase it's stability for any given trim setting.

    The flaps really do make a noticeable difference in how the plane flys

    Jason
    Last edited by jgerard; 06-15-2011 at 12:34 PM.

  22. #62
    skywagon8a's Avatar
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    Have any of you who have flown the new flaps looked back at the tail to see exactly what is moving? It is possible, for example, that if the stabilizer is doing the shaking that this is what is causing the elevator to move and that by fixing the stab shake the elevator shake will stop. Perhaps a diagonal stiffener in the stabilizer will do the trick? The only support that the stabilizer has are the flying wires attached to the rear spar tube. This allows the entire forward part to flex. Seems to me that I have seen the stabilizer on a stock Cub shake during some circumstances. I haven't flown one for a while though. Maybe it is the fin/rudder that is causing, through the brace wires, the horizontals to shake?

    These are just thoughts from one who knows no more about the flaps than what is in this forum. My 2c.
    N1PA

  23. #63

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    Doug, I have no idea if it is the same shake but I have had elevator shake on cubs with the flaps extended in to the fuselage. It was always with full flaps and quite a bit of power on. The worst was on a cub with .060 flat aluminum screwed to the bottom inboard end of the flap to extend. It was a slow fore/aft movement of the stick of less than a inch and didn't seem to bother much. I flew this cub a couple thousand hours and got completly used to the shake.

    Dave

  24. #64

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    We are working on a web site:

    www.performancestol.com

    It should be up sometime mid next week, it will outline cost and availblty for the experimental version of the double slotted Cub flaps.

    We will be testing a new stabilizer design this weekend with hopes that it will solve the stick shake concern. Again, the stick shake it a problem for certification only. We have not experienced any adverse negative flight charateristics other than a slight stick shake with over 100 hours of flight testing.

    Thanks,
    Doug

  25. #65
    Dave Calkins's Avatar
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    Doug, have you tufted the fuselage yet so see where the flap wash is hitting??????????

  26. #66

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    The tail shake is fixed!!!!!!!!!!!!!!


    I installed my new horizontal stabilizers last Friday and the tail shake is completely gone! The new stabilizers have the same plan form as the originals. The top surface is flat just like the originals, the bottoms have an airfoil shape which is hardly noticeable. My goal was to not alter the cosmetics of the Cub.


    I have called the DER test pilot to schedule another flight test to verify that the problem is fixed. I want to get his blessing before I go full steam ahead with the STC process. The bad news is that the STC version will likely need new horizontal stabilizers which will obviously increase the kit cost and the effort to get a STC.


    Experimental folks can purchase the flaps only if they desire.


    Doug

  27. #67
    Bugs66's Avatar
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    For experimental, will the kit allow the builder to customize the hanger spacing? Can there be 3 hangers as is in many experimentals?

  28. #68
    jgerard's Avatar
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    That's awesome Doug, glad to hear the new stab worked

    Jason

  29. #69
    Bill Rusk's Avatar
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    Outstanding!!!! and CONGRATULATIONS!!!

    Bill
    Very Blessed.

  30. #70

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    Bugs,

    The answer to your question is yes, I will provide the system to experimental folks in custom "build your own kits" as well a custom "pre-built" systems. The web site that should be up and running sometime next week will have pricing break downs for all experimental systems.

    I will not have pricing available for the stabilizers for a couple of weeks. I need to refine the drawing package on the stabilizers and get quotes to build them before I can publish a price. I do know that they will be more expensive than the Airframes, and Univair stock stabilizers. They are not as simple as the stock stabilizers and they weight about a pound more that the stock ones. These new stabilizers would likely be nice for nose heavy 180 Cubs, they will provide a lot more nose up authority.

    For experimental folks, I would suggest purchasing the flaps only first and trying them out. If you are uncomfortable with the stick shake you can add stabilizers at a later date. I think if I was experimental I would by-pass the new stabilizers. The stabilizers will only be required for certified Cubs. The stabilizers are direct replacements for the stock stabilizers, you would still use your old elevators.

    The purpose at this point to sell experimental kits is to refine the production process, detail drawing package, establish pricing from my vendors in quantities, and get people flying these flaps. I have machining, laser cutting, sheet metal forming, anodize, material vendors, fabricator/welding vendors that I want to give the opportunity to supply to me in a small production quantity. The only way to get the pricing reasonable is to order in a larger quantity. It cost me over $10k to build the first set including the stabilizers which is not acceptable. The refined system has more machining requirements in an effort to get the weight down. My goal is to break even on the first round of experimental and hopefully find other ways to get the cost down. I would like to sell large volumes with a smaller profit margin than a limited number of kits with a high profit margin. I think the modification is very worthy and I would like to see as many people as possible using it.

    I will be pursuing an STC as well, I think the certified market is bigger than the experimental market. Unfortunately the STC process will likely take a year or more to get through, please be patient certified cub owners, I will do my best to get it done ASAP.

    Thanks,
    Doug

  31. #71
    www.SkupTech.com mike mcs repair's Avatar
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    make sure you try to get your STC(s) written so stabs can be used alone like you said on nose heavy cubs and PA-12's..... bet you would make more easy $$ just from that.......

    (flip them to other sides for tail heavy ones )

  32. #72
    Bugs66's Avatar
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    Doug, sounds like most experimentals will be able to use. Very cool! I saw your demo plane flying around at JC. Looked impressive and like a well designed product.

  33. #73
    Iflylower's Avatar
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    Ok, my new question is about the new stabs. Are they better/more effective than stock? Did you inadvertently get into two new businesses? Tell us about the them. Could this be an improvement over stock without going the new flaps?

  34. #74
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Iflylower View Post
    Ok, my new question is about the new stabs. Are they better/more effective than stock? Did you inadvertently get into two new businesses? Tell us about the them. Could this be an improvement over stock without going the new flaps?
    thats also how day and nights long -12 flaps are stc'd, with the requirement of their other stc for square tail feathers.... but many just deviate from the flap stc and use regular-18 tail..... two stc would sound better, but probably more work?? $$

  35. #75

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    I do think the stabilizers are better than the stock and could be very useful to Cubs without the flap system. My goal was to fix the tail shake not re-invent the stabilizer. But now that I think about it they could be valuable to all the nose heavy 180 Cubs out there. It is not my intend to get into the stabilizer business, but it might happen if demand warrants. My priority is the flap system, I feel it really improves the Cub. I will put some pictures of the new stabilizers on my website that should be up and running some time this week.

    www.performancestol.com

  36. #76
    mvivion's Avatar
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    Doug,

    Did you ever give the strakes, ala Boundary Layer Air (now owned by CC) a try to see if they fixed the stick shake? Adding those would be a real simple program, much cheaper than new stabilizers, and they're already in production for that matter.

    MTV

  37. #77
    aktango58's Avatar
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    Very cool!!!!

    In MTV's line of thought, did the stick shake happen with VG's installed? Micro's are also mounted on the tail, (until you drag it through the brush)
    I don't know where you've been me lad, but I see you won first Prize!

  38. #78

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    I did try stakes, VGs, delta wings, and everything easy that I could think of but nothing worked. I really wanted something like VGs that would easily stick on and not increase the cost of production and certification, but I could not find anything that would work. The new stabilizer is the only thing that worked.

    I will need to remove the wing VGs for certification flight tests. If I leave them on than I will be required to have them on all installations which I don't want to require.

  39. #79
    Steve Pierce's Avatar
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    Had a tail shake on the Extra 330. We put some of that zig zag tape on top of the stab ahead of the elevator and it solved it but Extra would have no stick on band-aids and made some sort of permanent fix. I will find out what it was.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  40. #80
    skywagon8a's Avatar
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    Do you really need to make a whole new stabilizer? Could you get away with apiece of the correct shaped wood glued to the bottom of the ribs to form your shape and then some new fabric? This would save a lot of $$$$.
    N1PA

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