Trying to achieve turbonormalizing the home-built way

Discussion in 'Firewall Forward / Props / Fuel system' started by geosnooker2000, Aug 11, 2019.

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  1. Aug 20, 2019 #81

    rv6ejguy

    rv6ejguy

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    I read about this on VAF a while back. May be so, but in this realm, perhaps being conservative is safer, given the possible outcome?

    Would be interesting to see how the Barber Pole is driven in a Boeing. I think on King Airs I flew, it was strictly moved with pressure altitude. I am guessing both Beech and Boeing have done extensive instrumented testing to explore flutter limits to receive certification. I recall watching a YT vid of Airbus testing the A380 for flutter. A bit hairy.

    Hope to see both you guys at Reno again this year.
     
    Last edited: Aug 20, 2019
  2. Aug 20, 2019 #82

    SVSUSteve

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    Thank you! And just remember, if it’s above your pay grade, it’s in low earth orbit above mine.
     
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  3. Aug 20, 2019 #83

    SVSUSteve

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    Rolls-Royce has a video of the original design for mounting one of the Trent engines (I think it was the 900 for the 380) fluttering during a test flight. It’s absolutely terrifying to see. I am not sure if it’s publicly available. One of my friends who works for them as an engineer showed it to me.
     
  4. Aug 20, 2019 #84

    BoKu

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  5. Aug 20, 2019 #85

    Turd Ferguson

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    geosnooker2000, here's one you can deciper:

    Indicated speed is 265 (or mach .78). The barber pole (redline), not really Vne but close enough, is 288 (Mach .85). At the top of the MFD on the right side you can see the TAS is 460. And the best part is the groundspeed of 603. That's a good go-home leg. IMG_1469.jpg
     
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  6. Aug 20, 2019 #86

    BJC

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    Yes.

    Go to the link in post 62 for a discussion.


    BJC
     
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  7. Aug 20, 2019 #87

    geosnooker2000

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    All this "why" is interesting and all, but the "how" is what this thread is supposed to be about. And I don't mean increasing Vne. Please look at the thread title and respond accordingly.
    I have been (lightly) reprimanded here before for "thread creep", as have many of you. And I agree with the reasoning. For the sake of others searching for subject matter, let's keep things where they belong. I specifically went and started a thread in the aerodynamics sub-forum for this Vne stuff so that we could get back to economically turbonormalizing an 0-320 here.
    To allay y'all's fears, I do not intend to operate my Ch 640 outside the speed limitations stated by Zenair. It WOULD be nice if they published whether or not that 175MPH is IAS or TAS, but I'm going to take it as TAS until proven otherwise. If that means that I have a plane that is capable of flying to 20K, but it would be dangerous to exceed 16K, I will set an operating limit inside the POH of 16K. Or 15K. Or whatever it turns out to be to get to about 160TAS. The point of this exercise is that by the designer's own admission, the plane (normally aspirated at max gross) will not get even close to performance limits, at least until you hang a 540 on the front. That is going in the opposite direction of what I want to try. I want to try an 0-320 and achieve better cruise performance as a function of altitude, not brute force.
    Now, I WILL say, what Mr. Farnham has suggested in the SDS systems DOES interest me. $5700 is a chunk. But it sounds like it checks all the boxes of what I am trying to achieve.
    To borrow a phrase from Mr. Jon Croke, "Now Baaaack to [turbonormalizing]"
     
  8. Aug 20, 2019 #88

    BBerson

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    Title is "turbo normalizing" the "Homebuilt way".
    Is " supercharger normalizing" a Homebuilt way?
     
  9. Aug 21, 2019 #89

    geosnooker2000

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    I would say so for the most part since supercharger normalizing isn't that common among the modern certificated GA fleet? As long as you are trying to do it with automotive parts, I'd say you are following the spirit of what I'm trying to do. Or at least, non-TSO'ed parts.

    I think the overall point here is, an APV costs somewhere in the neighborhood of $1700. That's ridiculous for a part that probably is worth about $100 or $200 when you take out all of the BS liability insurance costs associated with it just because it goes on a plane instead of a car. Multiply that times all of the components in a Turbo system. That's what I'm trying to avoid.
     
  10. Aug 21, 2019 #90

    pictsidhe

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    There's a lot of super-normal people here ;)

    OK, OK. I'll make an on-topic comment, just to derail the thread ;)

    If you boost an engine and keep to its original power, you should be fine. You will likely need to blow extra air through the fins to keep it cool at altitude, but the innards will be seeing sea level stresses. If you boost to 15psi absolute, it'll run about sea level power. It will gain a little due to lower back pressure on the exhaust. Assuming you size the turbo properly...
     
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  11. Aug 24, 2019 #91

    TFF

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    The biggest problem you are going to have is the low boost you want to run. Tons of waist gates for cars on the market. Most are about more boost and spool up. The only other consideration is unlike racing where you want the waste gate closed until boost is exceeded, you want it controlled like a production auto where boost is always bleed, where you have excess until you get to your critical altitude. Waist gate closes progressively the height you go. Probably two waist gates. One for control, one for overboost runaway set 3-4 psi above control.
     
  12. Aug 24, 2019 #92

    pictsidhe

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    Use an ECU controlled type wastegate. A controller for that would not be complicated. I'd be surprised if someone didn't already make one.
    If they don't, well, maybe I should?
     
  13. Aug 24, 2019 #93

    Hot Wings

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    That is the path I'd take too. But then we run into the old 'which is more reliable, mechanical or electrical?' question. Lots of beliefs and emotional comfort levels involved with that debate.
    It's why I didn't offer this option way back when the thread started.
     
  14. Aug 25, 2019 #94

    pictsidhe

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    Well,
    Well, you could hook up a wastegate to a vacuum referenced pressure actuator, but they are hard to find.
     
  15. Aug 25, 2019 #95

    Hephaestus

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    In theory this would be a lovely scenario for a vgt and let the ECU manage it with a wastegate solely as a engine saver.
     
  16. Aug 25, 2019 #96

    poormansairforce

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    Um, how about operating it manually? No failures.
     
  17. Aug 25, 2019 #97

    Hot Wings

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    You mean other then the pilot? ;)

    It is odd how the most flexible and adaptable system on the plane can also be the greatest source of failure.
     
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  18. Aug 25, 2019 #98

    rv6ejguy

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    You guys are overthinking what's been done simply and reliably for decades on the automotive world. Get a Tial automotive WG with the lightest springs available, add a cockpit mounted $25 mini air regulator to provide control pressure to the top chamber- done.

    Same basic gear that most racers are running at Reno except they have much higher spring pressure in the wastegates.
     
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  19. Aug 25, 2019 #99

    pictsidhe

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    That's a manual control that will need tweaking with altitude. Set it for high altitude and forget to change it when descending, you have 12psi down low. That could have surprising results if you add a lot of power down low without resetting it. Going up is not an issue, it will just run out of power if you don't add boost.
     

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