Just talking about VWs

Discussion in 'Volkswagen' started by Pops, Mar 12, 2018.

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  1. Aug 13, 2018 #321

    Pops

    Pops

    Pops

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    More than observation, but a thorough test program to make all the performance graphs, V speeds, range, etc. A lot more than what is required for the Phase 1 test hours. I had more than 40 hrs in the test period in the little simple SSSC. Everyone who has flown it, said it was one of the best little airplanes they have flown. A lot of tweeking. Its all about the details.
     
  2. Oct 26, 2018 #322

    Pops

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    Wrong thread.
     
  3. Jun 4, 2019 #323

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    Pop,

    My Great Plains 2276CC with Revflow carb Cygnet cruise quite nice at 19.5inches of MP and 2850-2900 rpm. I believe about 45hp. 58x34 Ed Sterba Prop CHT ~305-315 on a 80 degree ambient. I climb to TPA at full power and back off to a cruise climb as needed to stay under 330f. The Cygnet flies great with two large souls and full fuel. I had a stud break after solo and made a precautionary landing without incident. On investigation I suspect the flaw was introduced when doable nutting the stud to install.. I decided to replace all studs with rolled 4130 studs and put new 040 heads from Mofoco. Standard valve size heads. Works great!

    https://www.youtube.com/results?search_query=nx237f

    Please share more about your circuit that automatically switches in the bleed down electric system. Pictures of your fly wheel drive will always be appreciated.

    Matt


    Matt
     
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  4. Jun 4, 2019 #324

    Pops

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    Haven't worked on it for a good while now, just trying to get the JMR finished and in the air. Then I will go back to working on that project.
     
  5. Jun 5, 2019 #325

    N804RV

    N804RV

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    My little Sonerai 2L has an 1835cc on a Dhiel accessory case. I believe it started out as a Revmaster conversion. But, it was totally rebuilt by a guy who put it on his Q2 for awhile, then decided he needed something else. It has a 69mm crank ground .010" under, entire mass balanced to within 1/100th gram. Heads are custom built by Fumio Fukaya. It has a Slick 4316 single magneto and a 30amp alternator whose sole task is to keep a small 12volt battery charged for running the fuel pump a couple of gauges and a cigarette lighter adapter powered hand-held radio.

    The "ready to install weight" is just shy of 150lbs (no starter or flywheel). And, fuel consumption in cruise is less than 3gph at 22" MP and about 3,150 RPM. The Sonerai, with me on board and 8 gallons of 92 octane non-ethanol, will cruise along at about 130mph. Take off ROC is about 750' at 90mph. Vx is 85. But, climbing out at 90 is easier on the engine and it doesn't make a whole lot of difference. CHTs are always about 375-390. And, I've had it up to 9,500' msl and it would still climb.

    [​IMG]
    [​IMG]
     
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  6. Jun 5, 2019 #326

    Vigilant1

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    The Sonerais and the VW are a good match. The color of the case and heads does look like the gold that Revmaster uses, and you've probably got the nice big front bearing that they use.
    What carburetor do you have fitted? If that's it attached to the air filter wrapped in plastic, it doesn't look like a Revmaster "Revflow" carb.
    I'm glad things are going well for you. A VW built right, maintained well, and run within its limits (esp CHT) can be a very reliable, economical aircraft powerplant.
     
  7. Jun 5, 2019 #327

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  8. Jun 5, 2019 #328

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    Great report how did you fit the alternator without a flywheel?

    Matt
     
  9. Jun 10, 2019 #329

    N804RV

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    Its a Zenith carb. It has a choke, as well as a one-off designed in-flight adjustable mixture. Its mounted so that it draws air from the lower cowl, no carb-heat, none needed.
     
  10. Jun 10, 2019 #330

    Dana

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    Why do you say no carb heat needed?
     
  11. Jun 10, 2019 #331

    N8053H

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    My 1/2 vw was setup this way also. Drawing air from the lower part of the cowl. It also did not require any carb heat.
     
  12. Jun 10, 2019 #332

    blane.c

    blane.c

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    No carb heat on an aircraft with carburation, is just a Social Darwinism experiment waiting for a foregone conclusion.
     
  13. Jun 10, 2019 #333

    akwrencher

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    Unless the air in the lower cowl is hot and dry enough already, making it full time carb heat.
     
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  14. Jun 10, 2019 #334

    blane.c

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    It was tribal knowledge that the "6" did not need carb heat, the idea of ever using it was scoffed at, then one nasty weather day a crew got in trouble almost crashed, the engineer pulled carb heat on a engine and it started to react to it and they hastily applied carb heat to the rest of the engines and climbed out over the rock pile in front of them.
     
  15. Jun 10, 2019 #335

    Mike Stewart

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    Is that from a book?

    If not . . . if you made it up . . . please write the rest of the story.
     
  16. Jun 10, 2019 #336

    blane.c

    blane.c

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    I didn't make it up, some friends of mine had some trouble after takeoff. They told me with the "big eyes".
     
  17. Jun 11, 2019 #337

    Vigilant1

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    The Revflow carb fitted to the Revmaster (and the similar Aerocarb/Aeroinjector, or the much loathed Posa carbs) don't have a venturi, so there's much less cooling in the carb body and a lower chance of icing (there's still >some< cooling due to evaporation of the fuel charge). For this reason, a lot of planes using these carbs aren't outfitted with carb heat if they draw intake air from a moderately warmer location within the cowling. I'm not saying it is right or wrong, but many folks have flown like this for a long time in conditions favorable for carb ice without a problem. But doing so with a conventional carb that has a significant pressure drop across the venturi is different, I would think.
     
    Last edited: Jun 11, 2019
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  18. Jun 11, 2019 #338

    blane.c

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    If you set up an engine to run off an air from an area of the cowling that is warmer then you are feeding the engine air that is less dense all of the time. So in a manner of speaking you are always taking off and flying with a certain amount of a density altitude penalty regards engine performance. While this may be working empirically for some to prevent carburetor icing, I would not trust it as it is not likely to supply the amount of heat necessary in the extreme. Additionally your engine always suffering from artificially running at a higher altitude will never cruise as efficiently while pulling the airframe through denser air. This may be a small difference in performance, but the smaller the difference in performance then the less likely that you have the carburetor icing protection needed in extreme conditions.
     
  19. Jun 11, 2019 #339

    Vigilant1

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    That's true, the performance is reduced compared to using cooler air.
    The temps in these carbs have been measured and the very slight temp drops have been validated, as has the effectiveness of using under cowl air to fix it. There are some national authorities that recognize the issue and waive their hard rqmtfor carb heat in planes set up in this way (again, with carbs of this type). In exchange for the slight performance hit, users believe they get simplicity under the cowling, simplicity of operation, and improved safety (planes with carb heat still ice up and crash with some frequency. We know the reason and the fix, but the situation remains).
    It is just another option. I'm not saying it is right or wrong.
     
    Last edited: Jun 11, 2019
  20. Jun 11, 2019 #340

    N804RV

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    I have left it the way it was when I bought it. No carb heat. I've put 170 hours on it, no problems. RIght or wrong, it works just fine. Come to think of it, in all my hours in Cherokee 140s with the MA-4 updraft carbs, I don't think I ever used carb-heat (except that time the CFI told me "hey, this ain't no Cessna. No carb heat unless you think you're actually experiencing carb ice.").

    As far as performance, that little 60hp engine speaks for itself. ;)
     

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