As we continue the flight testing of the Model 5, forward CG limit is one of the items yet to be settled. According to Bob - the limit is set when elevator control authority in the flare is inadequate.
I have been told different things from builders about the results of putting VG's on the hor stabs. Comments across a wide range. From it was terrible and made the plane unstable. To they really helped get more elevator authority. I do remember a couple builders of the original BH (flat tail ribs) had very good luck rectifying a forward CG problem caused by too heavy a prop on the front of a 540. 3 blade metal props can be problematic if you fly with little in the back - according to those owners. They said VG's on the bottom of the hor stabs really helped.
So please let me know what you saw placing VG's on the hor stabs. Best info would be from a Patrol or Model B with airfoil shaped ribs. Or even the Model A with the wood strips glued on the flat ribs to make them airfoil. I think a few are flying around now with those wood strips in place.
If the VG's helped please describe their placement. And if you can quantify the difference - that would be good. Meaning a before and after with just the VG's on the hor stabs. Not placing VG's on the wings at the same time. The info would really help us as neither Bob or me know a lot about VG's. And it seems possible that the forward CG limit could be different with VG's installed. Easy to test and find out.
Thanks to several of you we now understand where VG's on the wings are best placed. We intend to try the VG's on the wings and tail surfaces of the Model 5 after preliminary testing is done. Thanks in advance for your help. Mark
I have been told different things from builders about the results of putting VG's on the hor stabs. Comments across a wide range. From it was terrible and made the plane unstable. To they really helped get more elevator authority. I do remember a couple builders of the original BH (flat tail ribs) had very good luck rectifying a forward CG problem caused by too heavy a prop on the front of a 540. 3 blade metal props can be problematic if you fly with little in the back - according to those owners. They said VG's on the bottom of the hor stabs really helped.
So please let me know what you saw placing VG's on the hor stabs. Best info would be from a Patrol or Model B with airfoil shaped ribs. Or even the Model A with the wood strips glued on the flat ribs to make them airfoil. I think a few are flying around now with those wood strips in place.
If the VG's helped please describe their placement. And if you can quantify the difference - that would be good. Meaning a before and after with just the VG's on the hor stabs. Not placing VG's on the wings at the same time. The info would really help us as neither Bob or me know a lot about VG's. And it seems possible that the forward CG limit could be different with VG's installed. Easy to test and find out.
Thanks to several of you we now understand where VG's on the wings are best placed. We intend to try the VG's on the wings and tail surfaces of the Model 5 after preliminary testing is done. Thanks in advance for your help. Mark
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