Loading ...
Sorry, an error occurred while loading the content.

parting out N991X

Expand Messages
  • Rick Stockton
    While at Oshkosh I bought a computer program that basically tells you if you have a good designed airplane. I have spent the last two days figuring out the
    Message 1 of 10 , Aug 2, 2007
    • 0 Attachment
      While at Oshkosh I bought a computer program that basically tells you
      if you have a good designed airplane. I have spent the last two days
      figuring out the program. I have inputted my T2 into it and it will
      fly, but it way underpowered and way over weigh. I need to make the
      elevator bigger and make the wings longer. AL La Mini-Coup.

      Computer: Stall 75 Kts, Cruise speed 101 Kts

      I need to start work on the Europa and get RID of N991X. I checked
      with Steve of Great Plains at the show and he believes the engine is
      OK. I had a one blade prop strike. I did a dial check and the force
      One Hub flange is .002. Crankshaft was 0.00". I ordered a new prop
      from Jay Anderson and it should be here in two weeks.

      I want to sell the VW with the Electromotive Tec unit as one. The
      Electromotive system cost me almost $4500. Add the Engine and the
      prop. Not sure what somebody would be willing to pay, but I'd listen
      to any reasonable offer. I believe a can sell the Electromotive on
      E-bay and get most of my money back. This is a 2200cc, type IV, i
      beleive about 65HP. I have it limited to 3600RPM's

      I'd like to sell the airframe, but not sure if anybody would be
      interested as it looks to weight in at 310 lbs. It would need an 80
      HP Jabiru and that's $9K.

      If anybody is interested let me know.

      707-330-1717
    • s_a_black
      ... I make my living with programs like that. Don t believe ANYTHING a computer tells you until you have checked it. Input the numbers for a similar airplane
      Message 2 of 10 , Aug 2, 2007
      • 0 Attachment
        --- In AirVW@yahoogroups.com, "Rick Stockton" <airbearfedt2@...> wrote:
        >
        > While at Oshkosh I bought a computer program that basically tells you
        > if you have a good designed airplane.

        I make my living with programs like that. Don't believe ANYTHING a
        computer tells you until you have checked it. Input the numbers for a
        similar airplane whose performance you know and see if it checks out
        with the real airplane. Or, compare your aircraft's stall speed and
        climb rate with others that have similar wing loading and power
        loading. Unless you know what is in the program or what you could have
        done to mess up the input (wrong units or whatever) it could be
        misleading you. Maybe not, but you have to check it to make sure.
        Don't make a major life decision based on a computer program output.
      • Gary Gower
        Rick, Nothing more real that Scotts advice. Another advice, (0.02 worth), there are also several books by some known designers that write about this area of
        Message 3 of 10 , Aug 2, 2007
        • 0 Attachment
          Rick,

          Nothing more real that Scotts advice.
          Another advice, (0.02 worth), there are also several
          books by some known designers that write about this
          area of airplane design, Double check your numbers
          against the ones in that program, if you find serious
          diferences, then the imput or the way the program
          handles some formulas will not be OK for your projct.

          For example there are several very good computer
          programs about propeller design, but the results will
          not be accurate in the powered paraglider range, This
          dont make the a bad program, just that need adjustment
          to work in that speed and RPMĀ“s range...

          Good luck with your project, be the T2 or the Europa,
          Building and flying is great.

          Saludos
          Gary Gower.

          --- s_a_black <scott-black@...> wrote:

          > --- In AirVW@yahoogroups.com, "Rick Stockton"
          > <airbearfedt2@...> wrote:
          > >
          > > While at Oshkosh I bought a computer program that
          > basically tells you
          > > if you have a good designed airplane.
          >
          > I make my living with programs like that. Don't
          > believe ANYTHING a
          > computer tells you until you have checked it. Input
          > the numbers for a
          > similar airplane whose performance you know and see
          > if it checks out
          > with the real airplane. Or, compare your aircraft's
          > stall speed and
          > climb rate with others that have similar wing
          > loading and power
          > loading. Unless you know what is in the program or
          > what you could have
          > done to mess up the input (wrong units or whatever)
          > it could be
          > misleading you. Maybe not, but you have to check it
          > to make sure.
          > Don't make a major life decision based on a computer
          > program output.
          >
          >




          ____________________________________________________________________________________
          Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more.
          http://mobile.yahoo.com/go?refer=1GNXIC
        • Stefan Vorkoetter
          ... Don t know anything about that plane, but any small plane would have to have an awfully high wing loading to stall at 75kts. For example, for a Volksplane
          Message 4 of 10 , Aug 2, 2007
          • 0 Attachment
            Rick Stockton wrote:

            > Computer: Stall 75 Kts, Cruise speed 101 Kts

            Don't know anything about that plane, but any small plane would have to have an awfully high wing loading to stall at 75kts. For example, for a Volksplane to have a 75kt stall speed, you'd have to reduce the wing area to about 25% (for example, by having a 6ft span instead of the 24ft it has). Or, leaving the 100sq.ft wing, you'd have to increase the gross weight from 650lb to 2500lb.

            A _very_ rough rule of thumb that will give you a ballpark stall speed is

            15 x SQRT(wingLoading)

            where wingLoading is in pounds per square foot and speed is in knots. Don't use this to design planes, but if it gives you a vastly different stall speed than the program, than either the program, or your inputs to it, are suspect.

            --
            Stefan Vorkoetter
            Capable Computing, Inc.
            http://www.motocalc.com

            Small Things Aviation
            Electric R/C, Homebuilt, and General Aviation
            http://www.stefanv.com
          • Jack Dernorsek
            Stefan, More explanation please. SQRT, is that Square Root of the wing loading? And at what point does the speed come into play in your rough formula? One
            Message 5 of 10 , Aug 2, 2007
            • 0 Attachment
              Stefan,

              More explanation please. SQRT, is that Square Root of the wing loading? And at what point does the speed come into play in your rough formula?

              One more comment, and this is purely my eyeball engineer's two cents worth,

              no way that 75kts would mean a 6' wing on the Volksplane. I bet a twelve foot wing would give you 75kts.

              Again, my guestimate only.

              Jack

              Stefan Vorkoetter <stefan@...> wrote:
              Rick Stockton wrote:

              > Computer: Stall 75 Kts, Cruise speed 101 Kts

              Don't know anything about that plane, but any small plane would have to have an awfully high wing loading to stall at 75kts. For example, for a Volksplane to have a 75kt stall speed, you'd have to reduce the wing area to about 25% (for example, by having a 6ft span instead of the 24ft it has). Or, leaving the 100sq.ft wing, you'd have to increase the gross weight from 650lb to 2500lb.

              A _very_ rough rule of thumb that will give you a ballpark stall speed is

              15 x SQRT(wingLoading)

              where wingLoading is in pounds per square foot and speed is in knots. Don't use this to design planes, but if it gives you a vastly different stall speed than the program, than either the program, or your inputs to it, are suspect.

              --
              Stefan Vorkoetter
              Capable Computing, Inc.
              http://www.motocalc.com

              Small Things Aviation
              Electric R/C, Homebuilt, and General Aviation
              http://www.stefanv.com





              ---------------------------------
              Need a vacation? Get great deals to amazing places on Yahoo! Travel.

              [Non-text portions of this message have been removed]
            • Stefan Vorkoetter
              ... Yes, SQRT is the square root of the wing loading. Speed is the _result_ of the formula (i.e. 15 times the square root of the wing loading is a rough
              Message 6 of 10 , Aug 2, 2007
              • 0 Attachment
                Jack Dernorsek wrote:
                > Stefan,
                >
                > More explanation please. SQRT, is that Square Root of the wing loading? And at what point does the speed come into play in your rough formula?

                Yes, SQRT is the square root of the wing loading. Speed is the _result_ of the formula (i.e. 15 times the square root of the wing loading is a rough approximation of the stall speed in knots).

                > One more comment, and this is purely my eyeball engineer's two cents worth,
                > no way that 75kts would mean a 6' wing on the Volksplane. I bet a twelve foot wing would give you 75kts.

                The problem is that your eyeball is linear. Given that the weight stays the same, stall speed is inversely proportional to the square root of the wing area. So if you have only 1/4 the wing area, you'll have twice the stall speed (square root of 1/4 is 1/2, and the reciprocal of that is 2).

                > Again, my guestimate only.
                >
                > Jack

                Again, this is only a rough approximation, considering that all other things remain equal, but it'll tell you if your computer program is out to lunch or not.

                Try it on some real airplanes (anything from a 2' model plane to a 747).

                --
                Stefan Vorkoetter
                Capable Computing, Inc.
                http://www.motocalc.com

                Small Things Aviation
                Electric R/C, Homebuilt, and General Aviation
                http://www.stefanv.com
              • s_a_black
                Rick, give us the span and area and weight and I will take a crack at it. Just as a sanity check. Stefan can have a go too - as he has developed software for
                Message 7 of 10 , Aug 3, 2007
                • 0 Attachment
                  Rick, give us the span and area and weight and I will take a crack at
                  it. Just as a sanity check. Stefan can have a go too - as he has
                  developed software for this.

                  sb
                • s_a_black
                  I just looked up the specs on the T2. I plugged it into a spreadsheet that I put together to check the published stall speed of the CX4. I worked out max lift
                  Message 8 of 10 , Aug 3, 2007
                  • 0 Attachment
                    I just looked up the specs on the T2. I plugged it into a
                    spreadsheet that I put together to check the published stall speed
                    of the CX4. I worked out max lift coeff. based on aspect ratio for
                    several planes using the NACA 4412. I don't know the airfoil of the
                    T2 but it certainly looks similar from pictures I found and on my
                    graph it falls right beside the VP-1 and Flybaby, both very well
                    known designs so a Vs of 50mph at 585 lbs seems reasonable.

                    Now if your airplane is going to be heavier then the stall speed
                    will go up by the square root of the weight ratio so if your
                    airplane is 10% heavier than the spec weight (weight ratio is 1.1)
                    then the stall speed will go up by 5% (sqrt of 1.1).

                    The load factor at which the wing will fail will go down linearly so
                    if the airplane was stressed for 6g ultimate and yours is 10%
                    heavier then it will now only be stressed for around 5.5g.

                    This is of course a gross simplification but it gives you something
                    to work with. To have a stall speed of 75mph you would have to have
                    a gross weight well over 1000 lbs. Are you a Sumo wrestler by any
                    chance?

                    Sorry if this is too off topic.
                  • Jack Dernorsek
                    Hi Ryan, Can you elaborate on the flying qualities of the overweight Teenie with extended wings? Thanks, Jack Ryan wrote: I have flown an
                    Message 9 of 10 , Aug 3, 2007
                    • 0 Attachment
                      Hi Ryan,

                      Can you elaborate on the flying qualities of the overweight Teenie with extended wings?

                      Thanks,

                      Jack


                      Ryan <rryan@...> wrote:
                      I have flown an overweight Jeanies Teenie with extended wings. I
                      have to agree with Rick and not a simulation. ---Ryan

                      --- In AirVW@yahoogroups.com, "s_a_black" <scott-black@...> wrote:
                      >
                      > I just looked up the specs on the T2. I plugged it into a
                      > spreadsheet that I put together to check the published stall speed
                      > of the CX4. I worked out max lift coeff. based on aspect ratio for
                      > several planes using the NACA 4412. I don't know the airfoil of
                      the
                      > T2 but it certainly looks similar from pictures I found and on my
                      > graph it falls right beside the VP-1 and Flybaby, both very well
                      > known designs so a Vs of 50mph at 585 lbs seems reasonable.
                      >
                      > Now if your airplane is going to be heavier then the stall speed
                      > will go up by the square root of the weight ratio so if your
                      > airplane is 10% heavier than the spec weight (weight ratio is 1.1)
                      > then the stall speed will go up by 5% (sqrt of 1.1).
                      >
                      > The load factor at which the wing will fail will go down linearly
                      so
                      > if the airplane was stressed for 6g ultimate and yours is 10%
                      > heavier then it will now only be stressed for around 5.5g.
                      >
                      > This is of course a gross simplification but it gives you
                      something
                      > to work with. To have a stall speed of 75mph you would have to
                      have
                      > a gross weight well over 1000 lbs. Are you a Sumo wrestler by any
                      > chance?
                      >
                      > Sorry if this is too off topic.
                      >






                      ---------------------------------
                      Need a vacation? Get great deals to amazing places on Yahoo! Travel.

                      [Non-text portions of this message have been removed]
                    • s_a_black
                      ... Rick s prediction of 75mph was based on a simulation wasn t it?
                      Message 10 of 10 , Aug 3, 2007
                      • 0 Attachment
                        --- In AirVW@yahoogroups.com, "Ryan" <rryan@...> wrote:
                        >
                        > I have flown an overweight Jeanies Teenie with extended wings. I
                        > have to agree with Rick and not a simulation. ---Ryan

                        Rick's prediction of 75mph was based on a simulation wasn't it?
                      Your message has been successfully submitted and would be delivered to recipients shortly.