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Thread: R-3350 racers with a slow nose case?

  1. #11
    Join Date
    Sep 2011
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    Santa Fe, NM
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    176

    Default Re: R-3350 racers with a slow nose case?

    Just curious. If you put the R-3350 EA-2 slow nose gear reduction case on a relatively stock Sea Fury such as Sawbones, how much would the Reno lap speeds increase? Sawbones seems to be stuck around 420 mph in qualifying. Would the slow nose case get them significantly faster without any other air frame mods?

  2. #12

    Default Re: R-3350 racers with a slow nose case?

    Quote Originally Posted by Ken Adkins View Post
    Just curious. If you put the R-3350 EA-2 slow nose gear reduction case on a relatively stock Sea Fury such as Sawbones, how much would the Reno lap speeds increase? Sawbones seems to be stuck around 420 mph in qualifying. Would the slow nose case get them significantly faster without any other air frame mods?
    My take on it is that an aircraft may not gain any speed with just adding a slow nose case. If the engine is built, then the standard .4375 gear reduction becomes a limiting factor, and that is when switching to a slow nose case can make "faster" happen. A stock R-3350 probably would not benefit from the lower reduction.

    It is all about keeping the propeller tips below supersonic. Letís say that the perfect speed for the prop is 1,200 rpm. At that propeller speed, an engine with a .4375 reduction would run at 2,743 rpm, around max for a stock R-3350. But, if you have modified your R-3350 to make more power and you wanted to turn the engine faster, you are limited by the gear reduction because you must keep the prop at or below 1,200 rpm. Switching to a slow nose case with a .355 reduction allows you to keep the prop at 1,200 rpm, but the engine will now run at 3,380 rpm (23% higher rpm). An engine speed of 3,380 rpm is probably too fast for an unmodified R-3350, but that rpm may be ideal for one that is hand-built by people who know what they are doing.

    As RiffRaffRay was saying, Keenum acquired a .355 slow nose case but never used it on Race 99 because they never had a full-on race engine. The .4375 reduction was working fine for the power they had and the engine rpm they were running (this last sentence is me hypothesizing).

  3. #13
    Join Date
    Sep 2003
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    Lockport, Ill.
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    Default Re: R-3350 racers with a slow nose case?

    Bill,
    You are correct, on a stock motor the slow speed nose case won't help. We had tuned our motor to run what the Wright 3350 manual had specified as METO power. Alot of work was done with the carb jets and fuel flow as well as ADI settings. The most speed we gained was from drag reduction i.e. exhaust pipe angles, custom canopy and windscreen, gear door adjusments, wing and fuselage profiling. Kerch was a huge help with this. He sent me an engineering study done by Hawker in the late 40's. They were trying to break the world speed record for a prop plane and were looking at airframe modifications. It showed each mod and the amount of speed that was gained. We went from 376 in 1998 to 446 in 2009 using 2 stock motors from Aircraft Cylinder. Our crew cheif Jim Skinner did the best he could with the plane considering Mike also used the airplane for airshows and cross country flights.
    Ray

  4. #14

    Default Re: R-3350 racers with a slow nose case?

    Quote Originally Posted by W J Pearce View Post
    My take on it is that an aircraft may not gain any speed with just adding a slow nose case. If the engine is built, then the standard .4375 gear reduction becomes a limiting factor, and that is when switching to a slow nose case can make "faster" happen. A stock R-3350 probably would not benefit from the lower reduction.

    It is all about keeping the propeller tips below supersonic. Let’s say that the perfect speed for the prop is 1,200 rpm. At that propeller speed, an engine with a .4375 reduction would run at 2,743 rpm, around max for a stock R-3350. But, if you have modified your R-3350 to make more power and you wanted to turn the engine faster, you are limited by the gear reduction because you must keep the prop at or below 1,200 rpm. Switching to a slow nose case with a .355 reduction allows you to keep the prop at 1,200 rpm, but the engine will now run at 3,380 rpm (23% higher rpm). An engine speed of 3,380 rpm is probably too fast for an unmodified R-3350, but that rpm may be ideal for one that is hand-built by people who know what they are doing.

    As RiffRaffRay was saying, Keenum acquired a .355 slow nose case but never used it on Race 99 because they never had a full-on race engine. The .4375 reduction was working fine for the power they had and the engine rpm they were running (this last sentence is me hypothesizing).

    At 3200 RPM, the cooling fins on the top of the forged aluminum cylinder heads on the R-3350 get distorted and warped out of shape. I always took this as a sign that the head was about to be breached.
    As I recall, Curtiss Wright also said to scrap the whole engine if it hit this RPM or more. The big radials do not like high RPM!
    And yes, it is a Hemi.
    Last edited by toldjaso; 11-02-2017 at 07:29 PM.

  5. #15

    Default Re: R-3350 racers with a slow nose case?

    Thanks for the info!

  6. #16
    Join Date
    Dec 2002
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    1,644

    Default Re: R-3350 racers with a slow nose case?

    Did the Bearcat have a slow nose case on the FIFI engine?

  7. #17

    Default Re: R-3350 racers with a slow nose case?

    Quote Originally Posted by Race5 View Post
    Did the Bearcat have a slow nose case on the FIFI engine?
    Da

    Off 232
    Last edited by toldjaso; 11-05-2017 at 04:16 PM.

  8. #18
    Join Date
    Nov 2006
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    Boron,CA
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    317

    Default Re: R-3350 racers with a slow nose case?

    "We went from 376 in 1998 to 446 in 2009 using 2 stock motors from Aircraft Cylinder."

    What aero mod produced the largest single gain?



    Thanks, Kevin

  9. #19
    Join Date
    Sep 2003
    Location
    Lockport, Ill.
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    10

    Default Re: R-3350 racers with a slow nose case?

    Quote Originally Posted by FuryFan View Post
    "We went from 376 in 1998 to 446 in 2009 using 2 stock motors from Aircraft Cylinder."

    What aero mod produced the largest single gain?



    Thanks, Kevin
    The paint and airframe profiling gave us the most followed closely by the smaller canopy and windscreen. Both took months to complete but were well worth the effort.
    Ray

  10. #20
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    Sep 2011
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    Santa Fe, NM
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    Default Re: R-3350 racers with a slow nose case?

    Riff Raff rounding the pylons at 446 mph would sure be a welcome sight in the 2018 Gold race, just sayin...

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