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General control line discussion => Open Forum => Topic started by: Ted Fancher on December 06, 2017, 12:24:31 PM
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I wanted to re-read some info on Igor Berger's modified/improved flap drive mechanism and haven't found a search query that brings one up on Stunthangar. Anybody recall such a thing on the site? Have a link? Or am I imagining something that never was here? Thanks
Ted
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p.s. If there wasn't anything here and anyone recalls where it was discussed...S.N? M.A.?...I'd appreciate a heads up. thanks
Ted
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Igor will probably post soon, but a link here
http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=390821&mesg_id=390821&listing_type=&page=3
and within that, a link to his site showing a plot.
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Ted it sure was here somewhere, maybe in the building section. There is some info in there I’d like to copy some of. I have a few of his gadgets and forgot some of what I needed for them.
Dave
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Thanks, Fred. Just out the door to the gym and will look it up on my return. Appreciate the heads up.
Ted
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Ted it sure was here somewhere, maybe in the building section. There is some info in there I’d like to copy some of. I have a few of his gadgets and forgot some of what I needed for them.
Dave
Thanks, Dave. Thought I had searched the entire forum but I might just not have understood the search structure. Yeah, pretty much anything Igor posts is worth studying.
Ted
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Thanks Fred. The one I need is about the setup of the electronic stuff. I’m sure I’ll find it someplace.
Dave
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Hi Ted,
Igor has provided considerable information in Stunt News over the years. There was a two part series in the Jan/Feb and Mar/Apr 2013 issues. The second part described details of his Max Bee design and had a great photo of his control system. The first part describes, among other things about his models, his logarithmic control unit.
The stunt world is fortunate that Igor has been willing to share his information with us and a big thanks to Bob Hunt for making this happen.
You might be further interested in that Jan/Feb 2013 issue of Stunt News. The cover photo shows a National Champion holding a nice looking model called the Trivial Pursuit.
Keith
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I'm starting to get the feeling that Ted is thinking about re-entering the fray.
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Is this what you're looking for?
http://www.netax.sk/hexoft/stunt/the_max_ii.htm
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Is this what you're looking for?
http://www.netax.sk/hexoft/stunt/the_max_ii.htm
Thanx for that link, Steve. Looks like I'll be doing a little cogitating. Love to see a schematic of it in phases of action. At a glance it isn't yet obvious to me. Looks a lot heavier than a standard horn which gives a little pause.
Ted
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Thanx for that link, Steve. Looks like I'll be doing a little cogitating. Love to see a schematic of it in phases of action. At a glance it isn't yet obvious to me. Looks a lot heavier than a standard horn which gives a little pause.
I’ll send you a calculator that shows what it does for a given control geometry.
I have it on my current dog. I like it.
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I’ll send you a calculator that shows what it does for a given control geometry.
I have it on my current dog. I like it.
I'd appreciate that Howard. Do I understand correctly that the device's intent to to provide a variation in flap deflection based on total control input...i.e. less per degree of elevator at one end of the "cam" throw and more per degree at the other?? Any idea what the rationale for doing so might be? The unit appears to comprise a number of steel parts; is its weight an issue at all?
Thanks for your help. I'm just trying to stay abreast of the modern technology since the rebirth of interest in the old Imitation due to Mike Griffin's desire to kit the thing. Haven't paid a lot of attention to the technical progress in the hobby for a number of years now but...
Hope the Rushes have a Merry Christmas enjoying their lovely new "estate". Do you have tea in your library every day? ;) ;)
Ted
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Ted,
You still might look at those Stunt News articles I mentioned earlier.
Keith
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I'd appreciate that Howard. Do I understand correctly that the device's intent to to provide a variation in flap deflection based on total control input...i.e. less per degree of elevator at one end of the "cam" throw and more per degree at the other?? Any idea what the rationale for doing so might be?
It has the effect of giving you lots flap motion around neutral, and then progressively more elevator the further you deflect it. It's like having large flaps for rounds and smaller flaps for squares. You want the flap to improve the tracking in rounds and give you some feel in level flight, but less (just like the small flaps on the Imitation) to permit more elevator deflection in the squares.
Your solution (smaller/just big enough) flaps has the potential to have the problem that you had at the 2004 WC, e.i. not enough feel/too "pitchy", and that we later solved on that fateful flight afterwards by decreasing the relative elevator travel. This hypothetically removes any compromise you might have to make in flap area or relative motion to make it happy in both rounds and squares.
I have only flown one flight (Paul's first Predator) so I couldn't comment on the desireability. It is very closely related to a thread we had on SSW in the early 2000's that I cannot immediately find, the problem at the time being coming up with an acceptable mechanism to implement it. I think Igor was a participant in that thread but whether it influenced him or not, I don't know.
I would guess that it would greatly improve the various "giant flap" models and essentially addresses the issue we found with Paul Ferrell's profile Cardinal, just in a different way that does not require knives and saws. Hard to say how it would compare on a conventional model, or if you would want to make the flaps bigger but (just like the light handle thread), one disregards Paul Walker as one's own peril.
Brett
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I'd appreciate that Howard. Do I understand correctly that the device's intent to to provide a variation in flap deflection based on total control input...i.e. less per degree of elevator at one end of the "cam" throw and more per degree at the other?? Any idea what the rationale for doing so might be? The unit appears to comprise a number of steel parts; is its weight an issue at all?
Thanks for your help. I'm just trying to stay abreast of the modern technology since the rebirth of interest in the old Imitation due to Mike Griffin's desire to kit the thing. Haven't paid a lot of attention to the technical progress in the hobby for a number of years now but...
Hope the Rushes have a Merry Christmas enjoying their lovely new "estate". Do you have tea in your library every day? ;) ;)
Ted
Below is a picture of a sample flap-vs.-elevator curve. Elevator is linear with leadout travel (not shown), but flap deflection peters out at max control. The plot below shows some down elevator at zero flap, which how Impacts seem to trim out.
Igor gives his rationale in the references. He may not have mentioned that it gives more leverage over flap hinge moment (a big deal, as you discovered in your flap-trimming experiments) at high flap deflections. It works better than balance tabs-- better than my mechanization of balance tabs, anyhow.
Weight is an issue. Weight is particularly onerous aft of a control surface hinge. Michael Schmitt put his Igor mechanism forward of the flap hinge, which might be better.
Yes, stop by for some Rosie Lee when you're in the neighborhood.
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It's like having large flaps for rounds and smaller flaps for squares.
Well, sorta. You still have the full nasty flap chord, so hinge moment alleviation isn't as much as you'd get from trimming the flaps to optimize their size for square corners.
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Well, sorta. You still have the full nasty flap chord, so hinge moment alleviation isn't as much as you'd get from trimming the flaps to optimize their size for square corners.
Hmmm. I can't figure out how to express this well in English. For those of you who can read minds I'll just think real hard at my keyboard for a bit...
OK, done that. Now (poorly stated) English for the rest of you: if small flaps are good in the squares, why not use the Igor Flap Thing to give extra deflection on the small flaps around center, with full correct-for-a-square deflection at the extremities? Or is it just good to have a honkin' big flap hanging out in the wind as a sea anchor to hold down the amount of actual control deflection vs. handle deflection?
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The unit appears to comprise a number of steel parts; is its weight an issue at all?
Most of the extra weight is the extra 3 legged piece. The other parts should be similar weight to standard parts. The actual part with ball bearing installed, along with its center pivot rod and rod bearing is about 20.3 grams when made of aluminum. That is not overly lightened and is threaded for the bearing screw and ball links. Ball links are not included in the extra weight. Making the piece of carbon fiber could lighten that. That piece is mounted roughly 3" behind the trailing edge.
Shown on a profile plane here
http://flyinglines.org/planes.9.16.html
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Most of the extra weight is the extra 3 legged piece. The other parts should be similar weight to standard parts. The actual part with ball bearing installed, along with its center pivot rod and rod bearing is about 20.3 grams when made of aluminum. That is not overly lightened and is threaded for the bearing screw and ball links. Ball links are not included in the extra weight. Making the piece of carbon fiber could lighten that. That piece is mounted roughly 3" behind the trailing edge.
Shown on a profile plane here
http://flyinglines.org/planes.9.16.html
That is cool Fred! On a profile, the mechanism would inevitably be mounted in single-shear arrangement on the side of the fuselage. Did you do anything special to keep it steady?
(http://flyinglines.org/rfs.16.underwood.sharkS2.jpg)
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Brent, PM sent.
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if small flaps are good in the squares, why not use the Igor Flap Thing to give extra deflection on the small flaps around center, with full correct-for-a-square deflection at the extremities? Or is it just good to have a honkin' big flap hanging out in the wind as a sea anchor to hold down the amount of actual control deflection vs. handle deflection?
Looking at the data that Igor publishes about his planes, it looks like he typically uses pretty narrow chord flaps. This is the info for the Max-2 which is very similar to his winning MaxBee design.
18% root, 13% tip (inboard) 14.8% (outboard) = around 16% average.
(From my measurements of Igor's MaxBee plans published in Stunt News, it appears to use very slightly larger flaps for around a 17% average, around~20% root/14% tip)
http://www.netax.sk/hexoft/stunt/the_max_ii.htm
wing span- 1500mm (59 inches"
Wing area .42m2 (651sq. in)
chord root- 270mm
chord tip in -195mm
chord tip out - 195mm
root flap - 60mm
tip flap inboard - 30mm
tip flap outboard - 34mm
Average area flaps - 16%
thickness of airfoil - 20%
aspect ratio- 5.39
C/4 sweepback - 3.76 deg
taper - .69
(MaxBee) Stab/Elev. Span 760mm (30 in), area-% of wing 31%
Here is the elevator (x) to flap (y) ratio as used on this model with the pivot at 55%. Series 1 is 1:1 ratio, series 2 is Logarithmic device.
(http://www.netax.sk/hexoft/stunt/images/the_ma1.gif)
(https://stunthanger.com/smf/index.php?action=dlattach;topic=47192.0;attach=274235;image)
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I wanted to re-read some info on Igor Berger's modified/improved flap drive mechanism and haven't found a search query that brings one up on Stunthangar. Anybody recall such a thing on the site? Have a link? Or am I imagining something that never was here? Thanks
Ted
Ted I have that article on my server:
http://www.maxbee.net/download/MaxBee_1.pdf
http://www.maxbee.net/download/MaxBee_2.pdf
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This is the info for the Max-2 which is very similar to his winning MaxBee design.
Yes, MaxII was predecessor and it had the same wing and controlls, Max Bee had redesigned fuselage for better aerodynamics and for electric motor.
It was twin of MAX which had standard bellcrank, I did them just to see the difference. Both are on the same server.
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Thanx for that link, Steve. Looks like I'll be doing a little cogitating. Love to see a schematic of it in phases of action. At a glance it isn't yet obvious to me. Looks a lot heavier than a standard horn which gives a little pause.
Ted
Yes it is aproximately 30 or 40 g heavier, but it is not big problem to make 2cm longer wing to carry it :- ))
Right, I thought to make it lighter, for example composite or alu, but I prefer soldering classic bushing so solution was clear.
https://www.facebook.com/pg/MaxBee-363984487112995/photos/?tab=album&album_id=419666638211446
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Ted I have that article on my server:
http://www.maxbee.net/download/MaxBee_1.pdf
http://www.maxbee.net/download/MaxBee_2.pdf
thank you Igor. I'll check them out this weekend. Going to a play (Annie) with my son tonight.
Ted
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I see that Igor has removed the Max Bee plan from the PDF. It should be available from the PAMPA Plans Service: Plan PPN050, two sheets.
(Not listed on http://www.pampacl.org/index.php/plans ???)
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Looks like it is not up to date, here is screen shot from latest stunt news: