Doc James Hammond
Very Strong User
The reason why I am asking these questions is because the model will be a wingeron - if not then no need.
Wingerons - contrary to intuition, don't work better than conventionally controlled models that use camber changing (Ailerons/flaps/elevator). Its easy to see, and by now most people have observed how a conventional stabiliser with an elevator works better than the all-moving type. Its exactly the same with the wing, only more so. I know people naturally think that rotating the entire wing rather than that little flap MUST work better - but it doesn't. Like I said above - CAMBER CHANGING is the most efficient way to change the forces on the wing.
Raison de etre: But - Never mind that! Making a wood wingeron model because the world needs a wood wingeron model - especially a blast from the past - and by the way I heartly agree with this and I'm going to have one if it comes to pass, is cool - but it can have its problems due to the obvious mechanical necessities, etc but also aerodynamic problems.
Some well-meant advice - and I know the design is not set in stone yet.
First the section. Its marked on the orginal drawing as E374?? but I see you have E193 used??
E193 was a commonly used section in the early 80's and noted for its nice glide ratio, but NOT noted for its aerobatic ability. In fact quite the opposite. Despite its thickness, its virtually flat bottomed as you can see from your CAD sketches, so most if not all of the desired inverted performance will be lost. That might be something to consider before moving along. Use of the combination of E193 AND dihedral - even a little - will set that model on rails - until it goes off the rails - see below.
Next the wing planform. Is it the idea to follow the wing planform of the Ludion? If it is, then as its drawn on the orginal drawing will work well, maybe a little more rear sweep might help a bit more, but as you have it mapped out (I know its only back of the napkin sketch at the monent) with the bias towards a higher trailing edge taper and lower leading edge angle, then it might have stability problems and just let go if pushed too hard. See below (!)
Last, that Dihedral. If the combination of Wingeron, thick, flat bottomed E193 section, modified wing planform AND dihedral are used you will have a model that is so stable it will be very reluctant to do anything other than fly in a straight line, and will be self-correcting to the extent that it will fly like a Hobie, pendulum wise, swinging from side to side with any variation in the wind and will balloon on the turns. But if pushed too hard, with the taper of the wing biased towards the leading edge, a complex reaction between the CG, and Mean Aerodynamic chord may cause sudden stalling. Since Its likely to be a light model then these effects will be magnified.
If the model is outlined as per the original drawing, the section kept to the E374 that is marked on the drawing (I just checked) and the dihedral forgotten then it will be a lovely little responsive low wind sloper. But E193, forward sweep on the planform and dihedral will not produce the desired results.
Just some advice.
Doc.
Wingerons - contrary to intuition, don't work better than conventionally controlled models that use camber changing (Ailerons/flaps/elevator). Its easy to see, and by now most people have observed how a conventional stabiliser with an elevator works better than the all-moving type. Its exactly the same with the wing, only more so. I know people naturally think that rotating the entire wing rather than that little flap MUST work better - but it doesn't. Like I said above - CAMBER CHANGING is the most efficient way to change the forces on the wing.
Raison de etre: But - Never mind that! Making a wood wingeron model because the world needs a wood wingeron model - especially a blast from the past - and by the way I heartly agree with this and I'm going to have one if it comes to pass, is cool - but it can have its problems due to the obvious mechanical necessities, etc but also aerodynamic problems.
Some well-meant advice - and I know the design is not set in stone yet.
First the section. Its marked on the orginal drawing as E374?? but I see you have E193 used??
E193 was a commonly used section in the early 80's and noted for its nice glide ratio, but NOT noted for its aerobatic ability. In fact quite the opposite. Despite its thickness, its virtually flat bottomed as you can see from your CAD sketches, so most if not all of the desired inverted performance will be lost. That might be something to consider before moving along. Use of the combination of E193 AND dihedral - even a little - will set that model on rails - until it goes off the rails - see below.
Next the wing planform. Is it the idea to follow the wing planform of the Ludion? If it is, then as its drawn on the orginal drawing will work well, maybe a little more rear sweep might help a bit more, but as you have it mapped out (I know its only back of the napkin sketch at the monent) with the bias towards a higher trailing edge taper and lower leading edge angle, then it might have stability problems and just let go if pushed too hard. See below (!)
Last, that Dihedral. If the combination of Wingeron, thick, flat bottomed E193 section, modified wing planform AND dihedral are used you will have a model that is so stable it will be very reluctant to do anything other than fly in a straight line, and will be self-correcting to the extent that it will fly like a Hobie, pendulum wise, swinging from side to side with any variation in the wind and will balloon on the turns. But if pushed too hard, with the taper of the wing biased towards the leading edge, a complex reaction between the CG, and Mean Aerodynamic chord may cause sudden stalling. Since Its likely to be a light model then these effects will be magnified.
If the model is outlined as per the original drawing, the section kept to the E374 that is marked on the drawing (I just checked) and the dihedral forgotten then it will be a lovely little responsive low wind sloper. But E193, forward sweep on the planform and dihedral will not produce the desired results.
Just some advice.
Doc.
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