New two seater jet aircraft from Sonex

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by saini flyer, Jul 11, 2019.

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  1. Jul 12, 2019 #41

    Hephaestus

    Hephaestus

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    See I've been hunting for the fast personal transport with no baggage for a while... While not everyone - there's that market there.

    I keep hoping sonex or Vans would do something with the TP100 turboprop so that engine comes down into the less insane price point.
     
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  2. Jul 12, 2019 #42

    nerobro

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    The TP100 is.. deep into the "to much power" end of things. We really need a ~100hp turboprop.

    Turboprops are also "not the solution" to everything. If you like to throttle things back, Turboprops aren't your friend.
     
  3. Jul 12, 2019 #43

    BJC

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    Agree. It would be interesting to learn how many new parts had to be designed for either the single seat or the two seat version. I expect that the majority of parts are from their other, on-going kit planes, with the possible exception of some thicker skins, bulkheads or fittings.


    BJC
     
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  4. Jul 12, 2019 #44

    Hephaestus

    Hephaestus

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    At 140lbs we definitely need a smaller one... It would over power most 100hp airframes I'm sure. But it is technically a 100hp drive, they do have 40/80hp turbines too ;)

    I'm more of a speed guy, I like high and fast over low and slow. (But I'm trying to learn to like it, again partly why I'm shopping for a Challenger like option)

    With the current price of 100LL continuing it's insane climb, it's not hard for even a more utilitarian design to cost less per mile on jetA (just fuel costs). I keep hoping this smaller turbine market keeps evolving
     
  5. Jul 12, 2019 #45

    Hephaestus

    Hephaestus

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    I'm more of a market economist, you're well over a 100k to get into a decent turbine... This still comes in well below most turbo options even. I don't expect them not to place a premium on it, they've taken a risk, should be rewarded in my opinion.
     
  6. Jul 12, 2019 #46

    BJC

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    My comment was a response to gtae07 wrt developmental cost, which has a effect on profitability of the kit, but none on what they can, and should, charge. I think that they could (and probably should) charge more and not hurt sales. We’ll see what the response is at Oshkosh. I seem to recall a statement from them indicating that they have sold more single seat versions than they expected.


    BJC
     
  7. Jul 12, 2019 #47

    mcrae0104

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    I suspect the vast majority of the JSX-2/2T parts are not shared with any other Sonex product. They are not simply Waiexes (Waiexi?) and Onexes with a jet strapped on--they're completely different airframes.
     
  8. Jul 12, 2019 #48

    AJLiberatore

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    ;)...

    Many years ago when I had a serious mojo for a Davis DA-2A, a friend of my busting my chops at lunch said hey why don't you build one with a Jet on it. Napkin sketch ( which I need to find ) emerged in a flash that wasn't far off from this with a fixed gear. I guess I wasn't crazy after all. The things you see when you don't have an F-107 or a 382-10J handy ;).

    IMHO the Day a modularized E-Fan ( along w/ the batteries, yes I know that is the hurdle ) become a reality this config becomes the norm, I saw that potential w/ the Sonex as well....
     
  9. Jul 13, 2019 #49

    mm4440

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    Hi, small turboprop make little sense for normal aircraft. I was told by a Williams rep at Oshkosh when I asked why they did not seem to do shaft turbines, "The gearbox costs more than the core engine and you still need a prop and governor. A turbofan makes more sense."
    Small turbofans would be an improvement but can you buy one? Augmenters and afterburners are not too difficult to make for a small turbine. It is experimental aviation.
    I doubt if any companies in experimental aviation have product liability insurance. It both unaffordable and a lawyer magnet.
     
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  10. Jul 13, 2019 #50

    BBerson

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    They say the small turbofan is inefficient because the blade clearance loss to diameter ratio is unfavorable.
    So a whole new design is needed to get a large diameter with low power. Perhaps with fewer blades/nozzles.
     
  11. Jul 13, 2019 #51

    Turd Ferguson

    Turd Ferguson

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    N70CF was Corky Fornof's plane. The dataplate says Fornof Aerojet Special SN001. I was learning to fly in S. Louisiana in the late '70s' and flew into his base airport. Ran in to Corky and he invites me to come back in the hangar look at the new livery for the Sonic Drive Inn sponsor. I didn't know what a BD5 was, didn't know who he was, he didn't know me other than some goofy student pilot but he took 1/2hr out of his schedule to shoot the breeze and show me his planes. I knew what a BD5 was after that! What a stand up guy! Later they were doing a promo at the Sonic Drive Inn in my town, I stopped to look at the planes again and there was Corky and Bob Bishop. He remembered me from the previous visit at his hangar! He asked how I was progressing with flight training, again, what a stand up guy! Same goes for Bobby Bishop! I got to meet Corky again several yrs later when he bought a Pitts that had been crashed in an airshow and rebuilt by a friend of mine. By then I knew the Bearcat story with his dad, Bill Fornof. Have a lot of respect for Corky.
     
    Last edited: Jul 13, 2019
  12. Jul 13, 2019 #52

    Scheny

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    Our project, the Beast One is this competition, but we unfortunately just started. At first we wanted to have a 2- seater, but the intended jet engine, the DGEN-380 never entered series production and they offered it to me for 800k if ordered at low quantity.

    I don't understand how the PBS TJ100 can be sufficient for a two seater unless it is a glider... Only 1100N of thrust, so calculate for yourself. We said more than 400kg MTOW would be a no go.

    I was trained as an Airbus pilot before I got children and switched to automotive as a manager for big projects. I still often fly as a flight instructor for people who want to try an Airbus on the big Sim and also have hours on the Eurofighter and F16 full motion. Most of my trainers back then were fighter pilots, so I know what to expect from a small jet. In our opinion, the JSX has multiple shortcomings, that's why we started the project. I would be glad to share them, as other than Peter I like disclosure in front of experts instead of cheerleaders.

    Edit:
    The reason we did not go for the 2-seats: one PBS comes at roughly 60k and needs 40k in overhaul every 300h. So you will definitely not want to multiply this by two. In addition, the TJ100 can not be just exchanged by the TJ150, as it is neither man-rated, nor does it have a (sufficient) generator
     
  13. Jul 13, 2019 #53

    Kyle Boatright

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    The engine brochure says 1300N of thrust for 5 minutes. That's roughly 300 lbs of thrust in a 1500 lb airplane. Back of the napkin stuff suggests a takeoff roll of ~1500'. I don't see the problem, given this is advertised as a low performance jet.

    The optional engine has a bit more push (about 15%), and I'm sure will be the choice of most unless the price difference is substantial.
     
  14. Jul 14, 2019 #54

    BBerson

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    The HondaJet is 2.61 lb. per pound of thrust.
    The older corporate jets are around 4.0 lb. per pound of thrust, I think. Would need to compare with the BD-5J and others of similar wing loading.
     
  15. Jul 14, 2019 #55

    PW_Plack

    PW_Plack

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    I guess they'll just have to be happy selling their single-seater for 30% more than they paid for it.
     
  16. Jul 14, 2019 #56

    Kyle Boatright

    Kyle Boatright

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    The Sonex has a much thicker airfoil, a straight wing, and 2.3x the wing area of the BD5J at about 1.75x the gross weight.

    It isn't going to scorch down the runway or climb like a Harmon Rocket, but it'll still zip around pretty well. And, if the turbine acts like a turbine (i.e. reliable and maintenance free like a hammer), it'll make for a great Saturday morning airplane with relatively low time required for engine maintenance.
     
  17. Jul 14, 2019 #57

    Scheny

    Scheny

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    It's really easy: weight = 4x thrust as bare minimum (first generation jets and overloaded freighters), 3x as standard what to aim for (almost all current jets) and 2x or lower is high performance for military use. The JSX2 was already low powered at MTOW...

    The jet is only efficient at high speeds, so they show impressive climb rates most of the time (as this is all they got), but it will be at >100kt! A propeller plane of comparable weight and 100hp will have twice the thrust, but only for takeoff or lower speeds.

    You see, the trouble you run into is at low speeds, where induced drag will kill you on the left side of the drag curve. This is where the Beast One comes into place, as it is ~30% better at pattern and landing speeds than all comparable planes, while having the same performance at top speeds.

    Nothing about innovation or re-invention of the wheel. Just apply what's state of the art. Everyone tries to improve the top speed where it is impossible, we said instead let's take care of the left side where there is lots of margin left for improvement. Feel free to challenge the data, I am open to disclose the values.
     
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  18. Jul 14, 2019 #58

    BJC

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    What is the goal your project? A single airplane, plans for sale, a kit, or a production airplane?

    When will you start your build thread?


    BJC
     
  19. Jul 14, 2019 #59

    Scheny

    Scheny

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    I started a thread in aircraft design already. The build thread will start after summer with the full scale mockup I create for ergonomics.

    As the plane is built in composite and a lot of molds need to be built, the plan is to sell it as an experimental, but we have to evaluate how complete. Build assist seems the way to go.
     
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  20. Jul 14, 2019 #60

    BJC

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    Yes, I’ve been following it. I asked about a build thread because I’m eager to see the physical manifestation of your design work.


    BJC
     

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