Snake Oil or will it actually work?

Discussion in 'Maintenance Bay' started by farmrjohn, Sep 22, 2019.

  1. farmrjohn

    farmrjohn Pre-Flight

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    I ran across this product on the Aircraft Spruce site it sounds interesting. Google wasn't too helpful in tracking down much information, although the link on the AS site does list "approved" propellers. Any thoughts?
    PROPELLER VORTELATOR KITS FOR CERTIFIED AIRCRAFT
    http://tinyurl.com/y4v6hb3t (tiny URL is for a 92 character page from AS)
     
  2. Tantalum

    Tantalum En-Route

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    Seems dubious to me.
     
  3. Salty

    Salty En-Route PoA Supporter

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    I like the review.

    73560F0D-05EC-420F-971E-9021992841AC.png
     
  4. Bell206

    Bell206 Pattern Altitude

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    Don't know if it works, but don't see how they can produce or sell the product for a TC aircraft without a Part 21 approval like PMA/STC. Even Prop Guard has a STC. Usually Spruce is good about providing the docs but something seems amiss with this one especially since there is an "eligibility" list.
     
  5. Dan Thomas

    Dan Thomas Final Approach

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    First read about these 30 years ago. Not new at all.
     
  6. Tantalum

    Tantalum En-Route

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    The RPM thing doesn't make any sense to me. If the prop is producing more lift, that means putting a higher load on the engine, which entails a lower RPM. Not increase it

    Seems like trash to me. A $105 ribbed "for the propeller's pleasure" piece of tape
     
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  7. frfly172

    frfly172 Touchdown! Greaser! PoA Supporter

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    No listing for MT props.
     
  8. Rgbeard

    Rgbeard Cleared for Takeoff

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    I really love one of the testimonials, citing a 40 ft/min improvement in climb.

    SRSLY? And under what scientific study/control procedures did you measure this? Haha.
     
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  9. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    The inner part of the prop is pretty much stalled and just generating drag - reducing the drag would let the engine spin up faster. In theory. If they work.
     
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  10. alfadog

    alfadog En-Route

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    Looks like something that could work. I have no idea how much they would help or how long they will stay on or if they are actually legal though.
     
    Last edited: Sep 22, 2019
  11. Mark Lee

    Mark Lee Filing Flight Plan

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    works for wings why not props?
     
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  12. James331

    James331 Touchdown! Greaser!

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  13. Tantalum

    Tantalum En-Route

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    I heard fire stickers or ones that say "fear this", also add at least 10 horsepower
     
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  14. Jumpmaster

    Jumpmaster Pre-takeoff checklist

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    I installed chrome rocker covers. Added 5 kts in cruise. At least.
     
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  15. chemgeek

    chemgeek Cleared for Takeoff

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    When your supporting data is testimonials...well, just color me skeptical. This kind of thing COULD be objectively tested to determine if there is a statistically justifiable effect.
     
  16. IK04

    IK04 Cleared for Takeoff

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    Sticking tape on a part of the prop that creates no thrust?

    A thick layer of bugs will do the same for free...
     
  17. Huckster79

    Huckster79 Line Up and Wait

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    Come on, we all know light or heavy, hot or cold, humid or dry, altitude, etc has no effect on performance...
     
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  18. Skyrys62

    Skyrys62 En-Route PoA Supporter

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    Performance increase because your wallet is lighter.
     
  19. MooneyDriver78

    MooneyDriver78 Pattern Altitude

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    Looks like clear duct tape, punch some holes in it so it’s not so smooth. VGs help at high AOA, so maybe it would help in climbs but the inner part of the prop is moving so slow, I would think it would provide the same amount of thrust as a portable fan.
    I chock this up to placebo effect, paying $200 for 2 pieces of tape, I would be hoping for any benefit too.


    Tom
     
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  20. bflynn

    bflynn Final Approach

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    Wind tunnel tests are reported to show reduced drag, which does increase RPMs and speed because the prop doesn’t have to work as hard. Same idea as vortex generators on the wing, but applied to the spinning wing.

    There’s some science behind it. The wisdom and legality of using it is questionable. There are corrosion issues reported after removal.

    I suspect it does increase speed by a knot or two. You decide if it’s worth it.
     
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  21. Tantalum

    Tantalum En-Route

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    I get the science behind it.. but I'm extremely skeptical that this piece of tape helps facilitate that. How does someone with a 10 or 20 knot incremented steam gauge airspeed indicator confidently say they picked up 1-2 knots of speed anyway. I agree that these improvements are largely placebo. The real test would be to take a blind study so eliminate any confirmation bias or placebo.
     
  22. Salty

    Salty En-Route PoA Supporter

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    Yup. I ignore any claim of 5 knots or less. It’s below the ability to measure it accurately with all the variables there are to deal with.

    *And claims above 5 knots are probably provably false.
     
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  23. Skyrys62

    Skyrys62 En-Route PoA Supporter

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    Placebo effect can produce happiness/satisfaction, so it does have that value.

    I think Tom nailed it.
     
  24. Dan Thomas

    Dan Thomas Final Approach

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    That might hold true in the static condition, before the airplane is moving forward, but otherwise the relative wind speeds and blade angles are well within unstalled territory.

    The ones I read about long ago were applied to the entire blade span. One would think that if they were all that successful, they'd have beeen pretty popular and still in wide use.
     
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  25. Brad Z

    Brad Z En-Route

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    I own a Cessna 182. There literally hundreds of speed mods available for my airframe. I've installed them all.

    My 182 cruises at 310 ktas.
     
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  26. Tantalum

    Tantalum En-Route

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    to this point, I could see these making more sense on a constant speed prop where the VG's can be optimized for a given set of aerodynamic parameters. This piece of tape on the front of a fixed pitch prop is a gimmick
     
  27. NordicDave

    NordicDave Line Up and Wait

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    It’s likely in the same bucket as most “speed mods”, overly optimistic or unverifiable claims. 2-3 mph improvement? 2 mph is 1.7 knots, round off error in atmospheric conditions effecting flight.

    If this was a provable and durable improvement, the prop manufacturers would have adopted it years ago.
     
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  28. jaxcessnadriver

    jaxcessnadriver Pre-Flight

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  29. bflynn

    bflynn Final Approach

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    I must admit confusion to what you're trying to say. You called BS on it, then say you know the science, but then you deny the science.

    The testing wasn't done by the people buying this, it was done in test labs before it was sold. Are you calling the manufacturer a liar? That despite the science, you think it shouldn't work? That you don't understand it? It isn't worth it? Anyone who pursues a couple of knots of speed is a fool?

    There is such a range of things I could read into your posts.
     
  30. SoCal RV Flyer

    SoCal RV Flyer En-Route

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    5 extra knots for my checkerboard rudder. Well documented in the Van's community. :)
     
  31. chemgeek

    chemgeek Cleared for Takeoff

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    If you put flag stickers on your tail and orient them in the wrong direction, it takes 2 knots off your ajrspeed... :rolleyes:
     
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  32. Tantalum

    Tantalum En-Route

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    Trying to be less wordy. But since you asked:

    What I get the science behind:
    -Premise 1: That VGs work.. obviously. They're used in various applications to energize airflows, etc. So I "get" all that.
    -Premise 2: That the propeller is also a wing
    -Conclusion: That putting VGs on a propeller, in theory, could help the propeller operate more efficiently

    What I am dubious about:
    -just because the science supports it doesn't mean that this particular application will work as advertised. We get the science behind many things, doesn't mean we're able to put them all into practice

    -generating more lift, to make the plane go faster, would impart a higher load on the engine and decrease your RPM (at static sea level).. no? Someone else said that the idea is to kill the drag from the parts of the blade not generating lift, that's how they get 50 RPM gain.., which in turn makes the plane go faster since the lift generating parts go faster.. but don't most people pull their power back to a set POH cruise rpm setting anyway, or do all these users just elect now to cruise 50 RPM higher? If they're going to set the prop to their standard 2500 (or whatever) then we're expecting a ton of gains from a piece of tape that at the same rpm the prop is that much more efficient to have an appreciable gain in airspeed

    -1-2 knots in our planes is hard to measure. In the 172N (180) I used to fly you'd see anywhere from 112 - 117 KTAS depending on several factors.. these would be at your usual VFR 6,500, of whatever

    -the engineers who build our machines are smart people.. if it all took was some striations on the leading edges of the prop in various areas don't you think this would be done? The most advanced, modern, composite props don't have this feature. You don't see any commercial turboprops with this either... where being able to sell this kind of efficiency gain would actually be very valuable to all the Dash 8 Q400s flying around

    -when asked once (I heard this like fourth hand.. so tremendous gain of salt) why Airbus planes don't have all the little VGs on their wings that some Boeings do.. the response was that a well designed airfoil shouldn't need them. Maybe this was tongue in cheek, but there's merit to that

    -the propeller operates at a very wide range of angles of attach.. are these VGs optimized for low AoA (cruise) or high AoA (climb).. I doubt you can do both

    -not saying they're liars.. but the poster asked if we thought this was a gimmick, and I'm in the camp of it being a gimmick. Most people who are putting $200 tape on their props will likely be confident they felt a gain from it it as well
     
  33. Skyrys62

    Skyrys62 En-Route PoA Supporter

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    Common sense: 1-2 knots can be gained by washing/waxing your plane and losing a few lbs.
    Me: eh, I'll buy some tape.
     
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  34. Tantalum

    Tantalum En-Route

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    Can you imagine if you bought the stickers AND washed your plane? That's like 5 knots right there! After a few more after market speed mods you're probably looking at a 20 knot gain airspeed, and like a 300 RPM gain!
     
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  35. Mtns2Skies

    Mtns2Skies Super Moderator Management Council Member PoA Supporter

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    3773f04a996ee2a1b5747fd2d789742e.gif
     
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  36. chemgeek

    chemgeek Cleared for Takeoff

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    I'm curious about the physics of the purported treatment. The applied generators are on a portion of the blade with little absolute velocity, and they do not change the pitch of the blades. The only mechanism for increasing airspeed is to increase the efficiency of the propeller, but propellers are already highly efficient, and the vortex generators are not in an ideal location to have a large effect. The claims suggest that the generators are the equivalent of adding 1-2 inches of blade pitch, which does not seem credible.
     
  37. Tantalum

    Tantalum En-Route

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    All the while allegedly also making the engine RPM faster
     
  38. Cap'n Jack

    Cap'n Jack Final Approach

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    If the "vortelators" are vortex generators on tape, I wonder if someone got the idea from those large windmill blades. I've noticed vortex generators on those near the blade roots. I'm not saying they will (or will not) work for aircraft propellers.
     
  39. Unit74

    Unit74 Ejection Handle Pulled

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    And stalls at 25 dirty, right....?
     
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  40. IK04

    IK04 Cleared for Takeoff

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    ...And with that 125% fuel savings, you need an extra fuel tank to catch all that gas...