Twin Engine Corvair powered JAG-2

Discussion in 'Corvair' started by Daleandee, Sep 1, 2018.

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  1. Oct 24, 2018 #21

    blane.c

    blane.c

    blane.c

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    I think there should be another engine on the nose as well. That would make it a winner. Woot woot!
     
  2. Oct 24, 2018 #22

    lr27

    lr27

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  3. Oct 24, 2018 #23

    blane.c

    blane.c

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    Well same BS same challenge.
     
  4. Oct 24, 2018 #24

    TFF

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    Professional pilots are constantly tested on engine out flying. It's the weekend warrior that has trouble with twin ops. Years ago in Flying mag, I believe, they had the statistics of twin problems from the perfect pair. Bonanza and Barron. Bonanza pilots survived loosing their only engine more than the Barron guys loosing just one. Generally same airplane and same type of pilots. It's all about training and practice. Plenty of cases where the pilot secured the wrong engine, i.e. Shutting off the good one. Now you really have a problem. Side note at the airline I worked at, two pilots ferrying a plane stalled both engines at an extreme altitude they should not have been at. Locked both engines up so they were a glider. Had to get blown to 25,000 to start the APU. They destroyed both engines with a core lock. Of course crashed. One of the findings was there was no duel engine failure emergency checklist. Another set of pilots on a ferry flight in our old turboprop planes, got cute. Captain went to talk to the flight attendant and the copilot shut one of the engines down to surprise the capt. Of course it did but it freaked the FO out too. The restarts kept overspending the prop which shuts the engine down. Back and forth they would overspeed one and it would shut as they got the other started to just overspeed again. At least they survived and got it flying again at 1000 feet but the engines rolled the plane a couple of times on the way down. Of course they were seat of their pants chasing the plane and never got the checklist out to stop making their mistakes.
     
  5. Oct 24, 2018 #25

    BoKu

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    Nah. But if you want to show us a statistical analysis that bounds what the probability really is, that's cool.
     
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  6. Oct 25, 2018 #26

    proppastie

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    Estimated max gross: 2150 lbs
    It started life as an RV-6A (Van's site: 965 lbs empty, 1600 lbs gross).

    550 lb is a big jump......mounting the engines to the wings had to produce changes in the spars if they are mounted somehow to the spars.

    Edit: looked at more pictures.....and it is not clear if modifications of the spar were made.
    It still is quite an accomplishment, and given the scope and quality of the project one would surmise he did/had done the stress correctly.
     
    Last edited: Oct 25, 2018
  7. Oct 25, 2018 #27

    proppastie

    proppastie

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    Depends how you analyze or frame the question. Anecdotally I had 1 pilot induced fuel starvation incident and one ice induced fuel starvation incident in about 3500 hr. Had I been in a twin, both engines would have quit? So in the hypothetical twin fuel starvation twice the number of engines failed in the same period of time.
     
  8. Oct 25, 2018 #28

    lr27

    lr27

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    Unless there are a significant number of incidents in which one engine dies BECAUSE the other one is there, there can't be twice as many engine failure incidents in twins as there are in singles. Proppastie's post shows why. OTOH, I have no doubt the risk IS increased some.
     
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  9. Oct 25, 2018 #29

    blane.c

    blane.c

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    I think it is likely you will have an engine problem, not as likely to have a failure. I also think it doesn't matter how many engines you have, you are still likely to have an engine problem but not on all of them at the same time (usually). I also think odds are for idiots. I have listened to the logic of turbine singles being so reliable and reading of a turbine single crashing in the Amazon because of engine failure. It doesn't matter the odds when it happens to you. I will give up some efficiency for multiple engines, it is better.
     
  10. Oct 25, 2018 #30

    lr27

    lr27

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    Careful. With that kind of philosophy, you may be susceptible to buying too many lottery tickets.
     
  11. Aug 24, 2019 #31

    Daleandee

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  12. Aug 24, 2019 #32

    FritzW

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    ...a triple dog dare!!!!

    An engine has X probability that it will fail during Y hours of operation. 2 engines have 2X probability that one of them will fail during Y hours. ...or 1X probability that one will fail in 1/2 Y hours.

    A roulette wheel has a 1/38 chance of landing on a certain number in one spin. It has a 1/1 chance of landing on that number in 38 spins.

    If you pick two numbers you have a 1/19 chance of hitting one of them in one spin or a 1/1 chance of hitting one of the numbers in 19 spins.

    EDIT:
    Even simpler answer. ALL parts have a chance of failing. If you double the number of parts you double the chance that one will fail.
     
    Last edited: Aug 24, 2019
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  13. Aug 24, 2019 #33

    BJC

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    Anyone know how it performs on a single engine with the fixed pitch propellers?

    Reminds me of a blunt-nosed Wing Derringer.


    BJC
     
  14. Aug 24, 2019 #34

    Daleandee

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    No idea as I haven't seen any performance information or specifications given.

    Here is a video of the landing when it was taken over to the paint shop:



    Dale
    N319WF
     
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  15. Sep 4, 2019 #35

    radfordc

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    Nope. Just because the chance of hitting a particular number is 1 in 38 doesn't guarantee that the number will appear in 38 spins. Conside a coin toss. The chance of heads is 1 in 2...but you can flip the coin a 100 times and it's possible that it will come up tails every time. Possible....not likely.
     
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  16. Sep 4, 2019 #36

    radfordc

    radfordc

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    I don't know...but I like the quote from the builder,
    Remember, the glide ratio of ANY (properly flown) twin with an engine out is better than the glide ratio of ANY single with an engine out.
     
  17. Sep 5, 2019 #37

    FritzW

    FritzW

    FritzW

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    Of course it doesn't, if it did I'd be a rich man. I was just pointing out the basic idea.
     
  18. Sep 5, 2019 #38

    FritzW

    FritzW

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    True. But, unless the design has adequate single engine performance, you double the chance that your going to be gliding.

    I'm all for multi engine, I've got 7,500 hours as a LoadMaster on the Lockheed Tri-Motor (C-130). The more engines you have, the higher the chance you'll have to shut one down.
     
  19. Sep 5, 2019 #39

    proppastie

    proppastie

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    How many shut downs in 7500 hr.?
     
  20. Sep 5, 2019 #40

    FritzW

    FritzW

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    I'd guess well over a 100. BUT... most of them weren't the "oh s#it!, shut it down!" type. Most we're just precautionary. And a lot were prop problems, not engine problems.

    EDIT: when you have a fairly little airplane with four fairly big engines, it's best to shut down a questionable engine if you don't have a compelling reason to leave it running.
     
    Last edited: Sep 5, 2019
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