Geared Drives

Discussion in 'Chevy' started by akbuilder, Jan 26, 2007.

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  1. Jan 26, 2007 #1

    akbuilder

    akbuilder

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    Does anyone have any experience with the geared drive built by Bud Warren??
    His web site is GearedDrives.com, it looks like a good unit at a reasonable price. Any comments good, bad or indeferent?
     
  2. Jan 26, 2007 #2

    orion

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    It's really difficult to make off the cuff judgments without getting in deeper in order to analyze the details of the reduction's components. But at the same time there are a few comments that can be made based on what's presented at the site.

    1) Probably the first and foremost thing that strikes me is that the site claims the producer to be a very experienced machinist but does not mention anywhere his qualifications to design this rather critical component of the drive-train. There is no mention of engineering, his or anyone else's. As such, I doubt there was any serious work done on longevity calculations nor analysis for all the foreseeable flight loads. He seems to make the claim that static dyno testing and his so far short term installation on an Express is sufficient justification (not even close BTW) for the drive's reliability.

    2) To me the drive incorporates some red flags. The chief of these is the fact that the drive's case (which handles all the flight loads) reacts the internal forces into the flat end plates (with sharp corners!). The potential of cracking due to fatigue (looks to be cast material) is significant since this configuration might develop substantial flexing as a result of off axis flight loads (gyroscopic and maneuvering loads).

    3) The site presents several blanket statements that are made with no justification for the stance he takes. He seems to be of the opinion that planetary reductions and chain drives are insufficient for this application and that his spur drive is the only solution. This of course is not correct since any drive designed for the application and service environment should work well, regardless of the transfer mechanism. Even a cursory examination will show that a planetary drive for instance spreads the load over multiple contacts, thus reducing the tooth stresses, allowing for slightly smaller and lighter components. True, I too am a bit hesitant of drives that use automotive planetary clusters, but otherwise there is no practical reason why a single spur would be better than a planetary one if the latter were designed right. The same argument holds for silent chain drives - they are designed for service well within the rpm range of these engines and due to their configuration, they spread the contact load over many teeth, resulting generally in very durable mechanisms. Chain drives also tend to be quieter than many geared configurations but they can be heavier.

    There are several other red flags here but the above is sufficient in my book just to pass this one by.

    In my opinion, probably the best reduction drive for V-8s was developed by Mr. Geschwender. The drive business he developed is now for sale so I don't think any are available until they come up with a new owner, but this was one drive done right. You can look at some of his work at www.alternate-airpower.com.
     
  3. Jan 27, 2007 #3

    akbuilder

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    Thank you for the info Orion. that definetly looks like a much better unit.To bd its not available. I'm looking at options for when I get to the engine part of my build. I should start my build of an Wag-Aero sportsman 2+2 this summer. Have three thoughts for power, chevy V6, Eggenfellner Subaru, Wankel Rotary. Still have time to think it over though. The Chevy is looking like the lowest cost to get into the air though with availabe parts out there.

    Joe
     
  4. Jan 27, 2007 #4

    org

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    Has anyone checked out the VestaV8 unit? I'm curious about it but haven't heard of anyone actually using it.
     
  5. Feb 2, 2007 #5

    akbuilder

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    Orion I checked out the other drives that you have posted in other posts. How would an airboat drive work as a tractor drive rather than a pusher?? How would the bearings hold up to the loads or are they built to take a load in either direction?

    Thanks in advance.

    Joe
     
  6. Feb 2, 2007 #6

    orion

    orion

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    I've only seen one airboat drive a few years back (at it wasn't one of these) - they used ball bearings at all the critical points. Sticking with one bearing type made the drive cheaper (although a couple of pounds heavier) and the ball bearings run cooler and quieter than tapered rollers. The bearings were sized to be able to handle the thrust loading so the drive did not care whether it was a pusher or tractor.
     
  7. Feb 5, 2007 #7

    macosxuser

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    The 4.3 Chevy V6 always appealed to me, I wonder if either of those redrives would be durable enough for few few hundred hours on the front of an RV.
     
  8. Feb 5, 2007 #8

    orion

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    I would be willing to guess that it would. The service loads are similar and the airboat service environment tends to be worse than what your airplane would see. Besides, based on input from a few folks I've met that own airboats, some of them are literally beat to death throughout their life and the drives keep on chugging without a hiccup. Take care of them and keep the oil cool and they should do quite well on an airplane.
     
  9. Feb 5, 2007 #9

    akbuilder

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    Airboats are used alot here in Alaska during hunting season and listening to the way the throttles are used those drives are abused badly. Don't hear of too many going out though. I am also thinking of using an 4.3 Vortec on my Wag-Aero Sportsman 2+2. Still need to contact some of the manufactures to see if they are suitable for the V6. Thank you for the knowledge and valuable information that you provide to us begining home builders Orion.

    Joe
     
  10. Aug 20, 2009 #10

    flywulf

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    hello all,

    Orion,

    I wonder if you are familiar with the re drive designed by Jim Stewart. It is a spur gear reduction drive used on his scaled P-51 mustang.

    What are your thoughts about that design?

    Thanks,

    Eddie E
     
  11. Aug 20, 2009 #11

    orion

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    Do you have a link?
     
  12. Aug 20, 2009 #12

    MKIV

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    Hi Folks,
    A set of Auto trans gears I stumbled across that ''Might'' be of use for a geared reduction drive in the attached pic. They are from a Ford Telstar- Mazda 626 with either V6 or 4 cyl DOHC motor trans .---Ford probe might be the same thing. These are the idler & crownwheel & give a ratio of approx 1.8/1. Tooth counts are around 44/80. Center distance approx 6". In the car there is a smaller pinion gear as well to give the actual Final drive ratio. Width of gears is about 1.4" & they have approx 30° helical cut .

    Jac.
     

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    Last edited: Aug 20, 2009
  13. Aug 20, 2009 #13

    flywulf

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    i don't have a link to any sites currently. What I do have is a brochure that was available when the kit was being manufactured and sold. I will see about scanning it and post it as pic's on the site. If that does not work I will save them as PDF and send them to you. Might take a couple days to get it done.

    Ed
     
  14. Aug 20, 2009 #14

    orion

    orion

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    Looks like an interesting possibility. Would be interesting to see what alloy they're made from and to what quality they're manufactured to. Personally I would not recommend anything lower than AGMA 12 for airplane use but it may be possible to grind, hone and polish these to the necessary tolerances.
     
  15. Aug 20, 2009 #15

    Jan Carlsson

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    I meet Stewart in 1999, in Vero Beach, I remember he said the redrive was made by and sold as a Airboat drive, (for som (L)awful american reason) I don't remember the brand of the redrive, can it have just been named airboat drives? or something, it was made in Fl as I remember.

    Jan
     
  16. Aug 20, 2009 #16

    MKIV

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    In Sport Aviation 'June 1997' the engine 'A 502 BBC' was being promoted @ Sun n Fun by Total Engine Concepts( TEC) & the Re Drive was being promoted by ECM of Florida.
    1999 Oct Sport Flying saw the motor & re-drive @ Oshkosh with Precision Aero Engineering out of Torrance, Ca.
    I see no reference to the re-drive by any of these outfits by way of internet search today.

    Jac
     
  17. Aug 23, 2009 #17

    flywulf

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    It took a little bit to get it done as I figured it would.

    Orion, attached is the brochure for the redrive that Stewart 51 inc gave out with their info packet for the scale P-51. I have a hunch it is the same unit that precision aero eng. currently has.

    Again, what are your thoughts about this design?

    Cheers,

    Eddie E.
     

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  18. Aug 23, 2009 #18

    flywulf

    flywulf

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    Also,

    Here is a nice Pic of the unit on a S-51

    Cheers,

    Eddie E
     

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  19. Aug 24, 2009 #19

    orion

    orion

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    All in all, the documentation, such as it is, seems to describe a reasonable approach to the development of this box and quite frankly, their dampener idea is identical to a design that I used, so I certainly can't fault them for anything there. The document of course has no actual engineering info so posting any generalized commentary is only second-guessing their work.

    There are a couple of comments though that I can make based on what's there but again, without any detailed numbers to go on, this is just my two cents worth of opinion.

    1) The document continually refers to WWII era box designs as if they were the guideline for this particular product. I would certainly hope that this is used only as a guideline and that proper engineering and sizing analysis was used in arriving at the final configuration - not just the good old eyeball.

    2) The gear teeth were finished only to an AGMA 9 level finish. True, this reduction drive does not turn very fast so ultra-high precision may not be necessary but personally, I probably would not do a gear based airplane reduction drive with anything less than AGMA 12. I would also prefer to use a helical cut gear, not a straight spur (for less noise and vibration).

    3) I'm not necessarily thrilled with the design of the case itself. In flight, the prop generates a variety of moments and forces, the largest of which are those generated by gyroscopic loading. Some of the case's configurational details do not seem to be designed in a way that considers those types of loads.

    But as I said, this is simply off the cuff so should be taken with a grain of salt.
     
  20. Aug 25, 2009 #20

    flywulf

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    Thank you for your thoughts on this design.

    I am surveying all the available designs for reduction drives for my proposed replica fighter project. I am finding it very difficult to find a suitable unit to incorporate.I am seeking a design that can handle up to 800 HP. Again I am not a qualified and experienced aeronautical or mechanical engineer. I am hoping to use an existing unit that is available for purchase. My 2 cent survey looks like this,

    Geschwender- hy-vo chain design, out of production. Also I find it difficult to trust a chain.

    EPI- their first design failed in service. maybe the redesign will work as planned.

    American engine- not available, company dissolved

    blackhawk- not available, company dissolved.

    Cam- drive- I have no idea what happened with this organization.

    Stewart- company sold

    Precision aero- suitability and availability of unit unknown

    Orenda- too expensive

    Falconar- not available for purchase and probably too expensive if it was made available.

    Bud Warren- I get the impression that these are automotive components being used for the clutch drive. No known engineering analysis, seems risky to me.

    Prowler aircraft- not the HP range I am looking for. But seems to have a healthy track record.

    Vesta- I will have to see what they have available.

    I am doing first draft lofts of my project and the engine/redrive combo seems to be the most difficult item to place. WHich makes sense because the size of the pilot in a known quantity......:roll:

    Eddie
     
    Last edited: Aug 25, 2009

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