Rotec R-2800, R-3600 Q&A

Discussion in 'Radial's' started by Radialconversions, Feb 17, 2018.

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  1. Feb 17, 2018 #1

    Radialconversions

    Radialconversions

    Radialconversions

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    I’ve been operating the Rotec R-3600 for a few years now and have had good success on its installation. It took a lot of work to get it correct, but I think I’m there now with a safe installation. When I first got the engine all of the problems that were occurring in the field had just started to see daylight. All of the Rotec owners banded together and started to come up with ideas on what was wrong. What we found out was that most of the engine failures occurred not due to the engine, but the installation practices that were used. So we set out to identify each problem area and come up with fixes.
    Some ideas go as far as changing the oil tank design and some are as simple at running blast tubes to certain accessories. Anyway I know there are many concerns and questions about these engines. I’m here to answer any questions people have.
     
  2. Feb 17, 2018 #2

    Morphewb

    Morphewb

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    While it's admirable Rotec owners have banded together to fix ''what's wrong'' with the engine this is something that shouldn't have had to happen. Operating a dry sump radial engine hasn't been a secret for almost 90 years. Why was it left up to the customers to work out the bugs of the system while at the same time having to pay for that dubious honor? None of you should have had to ''come up with fixes''especially if you had to pay good money to do what the manufacturer should have done in the first place. Rotec had data available from years of operational experience on just about every radial engine manufactured since the mid 1920's. You guys shouldn't have had to pay to become beta testers on a technology that's been ''mature'' since long before I was born.
     
    Last edited: Feb 17, 2018
  3. Feb 17, 2018 #3

    Flyboyeaa

    Flyboyeaa

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    Brian, can you tell me about the accessory housing you are developing for the r3600?
     
  4. Feb 17, 2018 #4

    Bond007

    Bond007

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    Hey Ben I think the term guinea pig applies here
    Danny 007
     
  5. Feb 18, 2018 #5

    Radialconversions

    Radialconversions

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    Sure thing. It’s a new mini sump that integrates the sump, oil filter, oil pressure relief valve, and the check valve from my clean kit. It also adds a second scavenge port for the clean kit. By combining all of those components together into a single unit I’ll be able to eliminate about 10 feet of oil lines in my installation. The volume of the sump has also been increased as it extents in between the two lower cylinders. The stamped baffling I’m developing will work with the sump.

    3C02AA16-3858-4A4D-B351-69C5CAE58811.jpeg
     
  6. Feb 18, 2018 #6

    Flyboyeaa

    Flyboyeaa

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    looks like a much needed piece. Are you going to try to include a better breather into the engine also? Maby one that vents near the top of the crank case.
     
  7. Feb 18, 2018 #7

    IanJ

    IanJ

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    Can you provide a brief overview of the problems that were identified, and the proposed solutions? All the problem reports I've seen have been piecemeal and usually sensational, which leads me to question which hyperbolic report (angry owner or belligerent Rotec -- or more likely neither) to believe. It sounds like oil is a problem, but what about oil?

    Thanks for doing this, I'm very excited to get some straight answers about these engines!
     
  8. Feb 18, 2018 #8

    Lotahp1

    Lotahp1

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    I’m no engineer but that two bolt tiny mount flange looks problematic???? If that’s where that whole unit hangs from? Add the weight of oil and movement etc seems like some other braces might be needed? Again just my eye, maybe I’m not giving that little two bolt flange the respect it deserves ?

    Anyway to get Steve Wolff to chime in? I mean he designed a plane around one and now after a failure is not using that engine? Big name like Steve Wolff not using it causes some pause...at least for me.
     
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  9. Feb 18, 2018 #9

    Radialconversions

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    Not depicted in the drawing are two tabs welded to the sides that bolt onto the two lower cylinders. These tabs will have elongated holes to deal with cylinder expansion.

    I can’t speak for Steve. I worked with him on his Rotec installation. All he told me was he liked the sound of the Verner better. I’m sure the gear box is giving him pause as well. Even though his was a one off design that has since been changed.

    As far as the other challanges I’ll do a write up on them later tonight or tomorrow. Time for some family time. Happy Sunday everyone!
     
  10. Feb 18, 2018 #10

    Bond007

    Bond007

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    As well respected and as bad ass as Steve is I would say when he thru the Rotec out to pasture,that cast a black cloud on it for me
    Danny 007
     
  11. Feb 19, 2018 #11

    planebuilder

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    "These tabs will have elongated holes to deal with cylinder expansion. "
    So, won't that mean some movement, that might still allow fatigue up at the tiny 2 stud flange mount?
     
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  12. Feb 19, 2018 #12

    Radialconversions

    Radialconversions

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    So, yes, lots of the reports received have to be “sifted” as there is always emotion attached. Trying to get to the bottom of the problems and taking a logical step towards a perminant fix takes time and persistence. First off, every fix for an issue was done so with the full knowledge and cooperation of Rotec. We collaborated, and still do, on ideas to improve the product.
    So here is the list of known problems and the solutions to each one:

    poor oil scavenging,

    This was fixed with a two fold approach. First I ditched the banjo fittings that come standard with the engine. They are fine to use on the pressure side of a pump, but not the suction side. At the same time we upped the scavenge oil lines to -8 from the sump all the way to the oil tank.

    Oil foaming,

    This is actually no fault of the engine, but is responsible for a good number of the engine and gear box failures. I even had this problem on my Radial RV early on. Instead of coming up with a bandage fix I designed an oil tank that is made specifically for the engine. It spins the oil and drains through a series of baffling. I’ve never had an oil foaming issue since using the new tank.

    Hydraulic Lock,

    Welcome to Radial Engines. This is mostly operator error, and not understanding how to clear hydro lock before and during start.

    Engine driven fuel pump.

    It’s a small pump similar to what Rotax originally used. It has M6 barbs for the hose connections. Also it’s very weak for pulling fuel up hill for a low wing aircraft. I use compression fittings to convert the barb to an AN-6 fitting. Also I have a full time low pressure electric fuel pump that’s hooked up to a pressure switch in the oil system. Any time the engine is running the pump is running. This isn’t necessary for gravity fed systems. Also, if s boot cowl is used the pump gets very hot. We add a blast tube to the pump to help prevent vapor lock.

    Separate oil filter block,

    Nice as a remote mount, but adds quite a bit of oil line to the installation. My prototype sump with integrated filter is coming together.

    Ignition,

    Most of the failures have been Installation related. Many installations of the electronic ignition placed the coils and modules firewall forward with no blast tubes. This cooks the modules causing failure. By installing a cooling jacket on the components and ensuring secured connections the chance of failure is greatly reduced.

    The new engines have been greatly improved and are even better when care isn’t taken on the installation. My goal is to make the installation an easy process.
     
    Last edited: Feb 19, 2018
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  13. Feb 19, 2018 #13

    Radialconversions

    Radialconversions

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    Elongated means milled in the direction of cylinder expansion. No fatigue won’t be a factor.
     
  14. Feb 19, 2018 #14

    Flyboyeaa

    Flyboyeaa

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    Will the new sump also be vibration dampened by the rubber return hoses from the rockers and case drain backs?
     
  15. Feb 19, 2018 #15

    Radialconversions

    Radialconversions

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    No, those don’t provide any dampening, even on the old sump. This sump will be very sturdy compared to the old circular one.
     

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