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Old Jan 28, 2013, 09:40 PM
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John, thanks for speaking up. I'm encouraged to do what's familiar to me. Not much can go wrong, and if some shimming is needed, an evening's work makes it permanent and looking like the original design. And I'll find out in the first minute of flight whether I had a good idea or one that needed some adjustment.
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Old Jan 28, 2013, 10:08 PM
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John, thanks for speaking up. I'm encouraged to do what's familiar to me. Not much can go wrong, and if some shimming is needed, an evening's work makes it permanent and looking like the original design. And I'll find out in the first minute of flight whether I had a good idea or one that needed some adjustment.
Peter - The Mam is a fine beauty and I'm sure you'll do her justice. Keep us posted on build progress and what changes worked (and any that didn't). If I can help in any other way, let me know

Best regards, John
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Old Jan 29, 2013, 02:32 AM
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Honestly Peter, I really don't think you need to change anything; Vic Smeed models were designed to FLY, and that is exactly what they all do, adding radio just makes sure you keep your model! Changing rigging, tailplane sections etc will just make them fly differently - not better. For proof of this look at the scores - hundreds - of Tomboy models being flown with radio now.
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Old Jan 29, 2013, 07:20 AM
Edubarca
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Honestly Peter, I really don't think you need to change anything; Vic Smeed models were designed to FLY, and that is exactly what they all do, adding radio just makes sure you keep your model! Changing rigging, tailplane sections etc will just make them fly differently - not better. For proof of this look at the scores - hundreds - of Tomboy models being flown with radio now.
I couldn't agree more. Smeed's designs have always performed flawlessly without any modifications. No wonder his model airplanes are legends even today.
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Old Jan 29, 2013, 08:30 AM
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Steven Mettam's Mamselle was featured in the May/June 1995 edition of EFI.
Err, that's eighteen years Ray

Regards Ian
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Old Jan 29, 2013, 01:12 PM
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I couldn't agree more. Smeed's designs have always performed flawlessly without any modifications. No wonder his model airplanes are legends even today.
I certainly wasn't suggesting the plane needs changes. These are strickly a matter of improving the handling qualities under RC control which, of course, is highly dependent on builder/pilot preferences. That being said, I doubt any of the changes suggested will adversely affect the plane's performance

Take the example of wing/tail incidence - Virtually all older FF designs (pre-bunt designs) have several degrees of wing/tail positive relative incidence. They were designed this way for a good reason; so that they would climb in a steep spiral under full (constant) power and then glide at a lower speed such that maximum lift to drag could be achieved. As we all experienced at one point in our FF careers (at least I did many times), without enough rudder trim to keep it cork-screwing on the way up, it would loop over our heads, often sending us home with more pieces than we brought. In the content of RC control, where you'd like to fly in a straight line under power occasionally, you're pretty busy shoving various amounts of down elevator in with varying throttle settings when stock FF incidence settings are present. Reducing the wing/tail incidence reduces pilot work load under this common flight condition w/o measurably detracting from the low power/glide performance.

John
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Old Jan 30, 2013, 08:03 AM
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I certainly wasn't suggesting the plane needs changes. These are strickly a matter of improving the handling qualities under RC control which, of course, is highly dependent on builder/pilot preferences. That being said, I doubt any of the changes suggested will adversely affect the plane's performance

Take the example of wing/tail incidence - Virtually all older FF designs (pre-bunt designs) have several degrees of wing/tail positive relative incidence. They were designed this way for a good reason; so that they would climb in a steep spiral under full (constant) power and then glide at a lower speed such that maximum lift to drag could be achieved. As we all experienced at one point in our FF careers (at least I did many times), without enough rudder trim to keep it cork-screwing on the way up, it would loop over our heads, often sending us home with more pieces than we brought. In the content of RC control, where you'd like to fly in a straight line under power occasionally, you're pretty busy shoving various amounts of down elevator in with varying throttle settings when stock FF incidence settings are present. Reducing the wing/tail incidence reduces pilot work load under this common flight condition w/o measurably detracting from the low power/glide performance.

John
As well as elevator we now have the benifit of proportional motor control. If a models OK for free flight it's just a case of balancing these two during different flight phases without any need to make changes to the incidences.
If the relative incidence of wing & tail is reduced then the cg would need to be moved rearwards (increasing pitch sensitivity) & a different range of motor/elevator would be needed this time with the model inclined to fly more like an average sports model than a vintage one.
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Old Jan 30, 2013, 08:27 AM
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As well as elevator we now have the benifit of proportional motor control. If a models OK for free flight it's just a case of balancing these two during different flight phases without any need to make changes to the incidences.
If the relative incidence of wing & tail is reduced then the cg would need to be moved rearwards (increasing pitch sensitivity) & a different range of motor/elevator would be needed this time with the model inclined to fly more like an average sports model than a vintage one.
Right on the money patmcc, that sums it up perfectly.
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Old Jan 30, 2013, 02:04 PM
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Perhaps all these comments are the answer of my problem with all the Junior 60s I have built, I don't know. The problem is that although carefully built as per plan with exact incidence angles CG, good amount of downthrust, the model always acts as tail heavy and I have to permanently apply down elevator, even when the motor has cut. (I use 3 channel propo) Solution? Increase sharply the positive incidence of the stabilizer. This has cured the problem. but why then in 1946 the original Junior 60 flew with the force arrangement shown on the plan? Comments welcome although I'm not talking of the Mam'selle. By the way, I fly at 3.000 meters elevation with a Chinese ASP .21 which is very reliable and powerful. Flying the Junior with smaller engines didn't help to solve the problem.
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Old Jan 30, 2013, 02:49 PM
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Right on the money patmcc, that sums it up perfectly.
pat & Sun - Might I suggest an experiment --> take any of your current OT models with stock incidences and add a temporary shim under the TE of the wing so that you have 1~2 less positive incidence. No other changes. Fly it and let us know if you think it flew better or worse from a pilot workload standpoint.

John
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Old Jan 30, 2013, 04:05 PM
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pat & Sun - Might I suggest an experiment --> take any of your current OT models with stock incidences and add a temporary shim under the TE of the wing so that you have 1~2 less positive incidence. No other changes. Fly it and let us know if you think it flew better or worse from a pilot workload standpoint.

John
Don't need to fly one to know what would happen John; Unless I moved the CG back, which would mean decreased longitudinal stability and hence higher pilot work load I would have to hold in some up elevator which as far as I am concerned would also be an increase in pilot workload. The whole essence of a converted F/F vintage model is that, properly powered with the right incidences, it will climb if enough power is applied; solution if you don't want it to climb, throttle back, it will then fly level and with a further reduction, descend. That is how full size aircraft (other than vastly over-powered jet fighters which equate to our equally vastly over powered 3D models) climb and descend, they increase or reduce power. With my aerobatic models I trim for straight and level flight at full power which means zero-zero incidences and enough side thrust to counter the torque, ideally the model will continue in the direction it is pointing until I apply a control input to change that. But these converted vintage Free-flighters are not that type of model they have a degree of automatic stability. Yes, you CAN play with the incidences to make them fly that way, but the result is always not as good as a model designed to fly like that from the start, and certainly less pleasing for that particular type of model.
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Old Jan 30, 2013, 04:42 PM
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Don't need to fly one to know what would happen John; Unless I moved the CG back, which would mean decreased longitudinal stability and hence higher pilot work load I would have to hold in some up elevator which as far as I am concerned would also be an increase in pilot workload. The whole essence of a converted F/F vintage model is that, properly powered with the right incidences, it will climb if enough power is applied; solution if you don't want it to climb, throttle back, it will then fly level and with a further reduction, descend. That is how full size aircraft (other than vastly over-powered jet fighters which equate to our equally vastly over powered 3D models) climb and descend, they increase or reduce power. With my aerobatic models I trim for straight and level flight at full power which means zero-zero incidences and enough side thrust to counter the torque, ideally the model will continue in the direction it is pointing until I apply a control input to change that. But these converted vintage Free-flighters are not that type of model they have a degree of automatic stability. Yes, you CAN play with the incidences to make them fly that way, but the result is always not as good as a model designed to fly like that from the start, and certainly less pleasing for that particular type of model.
Sun - I'm really not looking for an argument here, but are you suggesting that to achieve a 'make it go where you point it at various power settings' you have to move the CG so far back that it's unstable/unflyable; just because it's a FF design? If so, that's simply not the case. Just like you pointed out for aerobatic models, there's benefit to lowering the relative incidences to achieve a 'go where it's pointed' result which is equally useful in tweaking a FF design for RC use. My experience across 4 OT models with this change is that they still fly beautifully in all other respects such as glide and cruise while mostly eliminating the throttle/pitch coupling of the original design.

This is my last post on this point.

John
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Old Jan 30, 2013, 05:08 PM
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pat & Sun - Might I suggest an experiment --> take any of your current OT models with stock incidences and add a temporary shim under the TE of the wing so that you have 1~2 less positive incidence. No other changes. Fly it and let us know if you think it flew better or worse from a pilot workload standpoint.

John
John, if the wing incidence is decreased it will cause a decrease in the motor's down-thrust.
I always adjust the elevator & tweak the cg as necessary in the normal trimming process of any newly built OT model until it will fly hands off at low throttle. I've never yet changed the wing incidence or bothered to shim the tailplane seat.
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Old Jan 30, 2013, 05:18 PM
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Edubarca, I've nearly finished re-furbing & electrifying a Junior 60. I don't want to hijack this thread so when the Jnr's complete I'll open a new thread & perhaps we can discuss it in some detail comparing it with your experiences.

BTW I'm at sea level - about 200 yards horizontaly & 50ft above as I type.
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Old Jan 31, 2013, 06:31 AM
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John; the last thing I wanted to do was start and argument, I was merely pointing out that I know how my models fly and hence know perfectly well what the effect of reducing the wing incidence would be. Obviously my set-up works for me on the dozen or more vintage/nostalgia F/F conversions I have set up this way, yours works for you, fair enough there are usually more ways than one of achieving something. The point I was trying to make is that there is no NEED to change the setting in 99% of cases unless the model is either over-powered or you want to achieve different flying characteristics which suit your flying style better.

With that I'll shut up and apologise to PeterH for hijacking his build thread, I am looking forward to seeing the Mam'selle take shape and wish you success with it Peter, whatever set up you use.
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