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Biplane Wing Incidence - Well kept F3A secret or nobody knows for sure.

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Old 03-09-2014, 01:56 AM
  #26
serious power
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' Flying characteristics will change with flying speed if incidences are in play. ' Quote.

I think this statement has merit in this discussion.
I have to say that the Matt bipes really fly well.
I'm sure they, both top pilots, will have learned a lot through the development of the Amethyst in it's various guises. It really was an exercise in function over form. Stephan Kaiser who also flies there and with the Matt bipes is also a really good pilot. A lot of intellectual capital feeding into that exercise.
So to see their bipe set up with both wings the same is interesting and one would be unwise to ignore.

Brian

Last edited by serious power; 03-09-2014 at 04:08 AM. Reason: addition
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Old 03-09-2014, 04:25 AM
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Quote:
Originally Posted by serious power View Post
Hi Chad,
Thanks.
So your motor is 1.6 deg from square to the wings ?

Brian
Yes that would be pretty close, down thrust.
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Old 03-09-2014, 04:26 AM
  #28
Malcolm H
 
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Bryan,

Care to share the Shark incidence setup?

Malcolm
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Old 03-09-2014, 06:56 AM
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I forgot to mention one important point about incidence. I am referring to everything on "zero" with a fully symmetrical airfoil. Symmetrical airfoils require angle of attack to generate varying degrees of lift while semi-symmetrical airfoils require incidence to counteract lift while the model flies in SLF.

A trainer model is a perfect example of this. With a flat bottom wing the plane can only be trimmed for SLF at a particular throttle setting. Adding or decreasing power past that point and your throttle, in essence, becomes an elevator. I'm sure you all understand this but I am just using it as an extreme example. I don't know of any biplane that use flat bottom wings except maybe the old "Big John" or "Lazy Ace" style bipes and they are in no comparison to a F3A bipe but while studying "aerodynamics 101" the rules of flight are consistent, only the parameters of the airframe are different.

The perfect airframe setup for "0-0-0" is a plane that the wing and stab are on the exact same centerline as the engine. Any deviation from this platform will result in the need to tweak the flying surfaces. A nice straight arrow will fly perfectly straight but put a Z- bend in one and see what happens. Same goes for an airplane. Once you start moving things away from the centerline of flight things change dramatically.

Look at todays modern single wing aerobatic aircraft. They are the epitome of advanced aerobatic design BUT who can pass up the appeal of a biplane. I know I can't!

Please keep in mind that the comments I am making refer to aerobatics only.
Scale models , along with other types of specialized flight, is a whole different ball game.


I hope you guys don't think I am getting too far off topic considering the OP was directed at F3A biplanes but the OP said
any input was welcome. I'm going back down to my building board now. This is an interesting forum and hopefully it will
not end up in another hair balled argument like so many others.

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Old 03-09-2014, 11:30 AM
  #30
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Hi Brian,
Look forward to seeing your new creation (at Kent?).

Re incidence - can't think why incidences on each wing would need to be different for pattern. What would be the advantage of 1 wing stalling & t'other still flying, say - in spin entry.

Also F3-A people don't forget - no matter what incidence you 'think' you set on the model - the model will always fly at the correct incidence to fly level. You set the incidence with elevator trim in flight. If you try to use exessive incidence - all that happens is the fuselage then fly's tail up or down. Its impossible to get around this simple aerodynamic fact.
regards
Stuart

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Old 03-09-2014, 01:37 PM
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Hi Stuart,
I'm sorry to say there will be no trip to Kent for me this year - the 'creation' would not be ready for then anyway.
Hoping to get to Liechtenstein and that's early July.
I might debut it at the Triple Crown which I will be attending regardless - we have a title to defend .
See you then ?

Brian
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Old 03-11-2014, 11:55 AM
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Hi Brian,

Sorry you can't make it to Kent. See you at TC - & we can talk incidences!

regards
Stuart
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Old 03-12-2014, 09:28 AM
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Quote:
Originally Posted by Malcolm H View Post
Bryan,

Care to share the Shark incidence setup?

Malcolm
Indeed....Bryan is the best guy to comment on PATTERN Bipes. (capitals to make the distinction; we don't want scale set-ups). He has done more work (experimentation) on this than most. I will share only the fact that Bryan threw out practically all previous concepts on how to set-up a PATTERN Bipe and started with a clean slate. His results (Brett W) speak for themselves.

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Old 03-12-2014, 10:58 AM
  #34
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Matt I agree that Bryan is the man when it comes to these things. Either he hasn't seen this thread or he is being tight lipped. If it's the latter can't really blame him as he is the one who put in the work. I may send Dick Hanson a line to see what his views may be as he was quite successful designing bipes for some of the TOC guys. I'm interested because I just picked up a new YS 115 for pylon racing but don't really want to have the engine not being used most of the time. I was thinking a 60" 850-900 sq in pattern bipe would be just the ticket.
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Old 03-12-2014, 12:19 PM
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Naruke's Accuracy has a 0.5 degree difference between top and bottom wing

Quote:
Matt I agree that Bryan is the man when it comes to these things. Either he hasn't seen this thread or he is being tight lipped. If it's the latter can't really blame him as he is the one who put in the work. I may send Dick Hanson a line to see what his views may be as he was quite successful designing bipes for some of the TOC guys. I'm interested because I just picked up a new YS 115 for pylon racing but don't really want to have the engine not being used most of the time. I was thinking a 60" 850-900 sq in pattern bipe would be just the ticket."

I had been flying an Naruke Asyuler which was setup using Bryan's Triangulation method, I bought the trim guide from Bryan last year and really liked the way the model flew. I asked Brian if he had any ideas for setup on the Acuracy but as he has no experience with the model he was unable to offer any guidance....

Niall

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Old 03-12-2014, 06:18 PM
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I know Bryan well enough to know that after reading these posts he's glad to see his bipe trimming methods are still well undiscovered!

Plainly stated, Bryan has devoted his entire adult life to this hobby and deserves every bit of credit he seems to finally be getting!

Brandon Landry
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Old 03-13-2014, 03:07 AM
  #37
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Hi,
This is NOT intended to be a 'Trimming' thread.

Adjusting incidence is near impossible or at least very difficult on many of the current biplane designs.
There also seems to be a information/knowledge gap but for a few spurious ideas with little foundation.
Multiple adjustments are just not on with these designs - it is a bit of a one shot deal and it is a pity if people are trying to sort a poor set up or if they try to change the set up in a knowledge void.

I'm hoping this can be a thread where people share what they know or what they have - maybe we will find some consensus on a 'good' fundamental set up for F3A biplane wings incidence wise.
So just information on existing and or best potential wing incidence set up please.
There are quite a lot of people flying bipes now including some top pilots so there must be a growing knowledge/experience pool.

I have started this in the belief/hope that this is a sharing and helpful community.
If you have nothing to say then it is best to say nothing at all.

Brian

Last edited by serious power; 03-13-2014 at 03:12 AM.
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Old 03-13-2014, 03:08 PM
  #38
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Hi,
Can anyone else confirm that their Accuracy has a 0.5 deg,, variance between top and bottom wing - I assume the top is -ve relative to the bottom ??
Thanks.

Brian


Quote:
Originally Posted by Niall View Post
Naruke's Accuracy has a 0.5 degree difference between top and bottom wing

Quote:
Matt I agree that Bryan is the man when it comes to these things. Either he hasn't seen this thread or he is being tight lipped. If it's the latter can't really blame him as he is the one who put in the work. I may send Dick Hanson a line to see what his views may be as he was quite successful designing bipes for some of the TOC guys. I'm interested because I just picked up a new YS 115 for pylon racing but don't really want to have the engine not being used most of the time. I was thinking a 60" 850-900 sq in pattern bipe would be just the ticket."

I had been flying an Naruke Asyuler which was setup using Bryan's Triangulation method, I bought the trim guide from Bryan last year and really liked the way the model flew. I asked Brian if he had any ideas for setup on the Acuracy but as he has no experience with the model he was unable to offer any guidance....

Niall

Last edited by serious power; 03-13-2014 at 03:11 PM.
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Old 03-16-2014, 10:01 AM
  #39
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Mine should be coming coming around the end of the month, I will measure it all up when I get it. If it's anything like the Citrin, then it should be pretty much mix free.


Quote:
Originally Posted by serious power View Post
Hi,
Can anyone else confirm that their Accuracy has a 0.5 deg,, variance between top and bottom wing - I assume the top is -ve relative to the bottom ??
Thanks.

Brian
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Old 04-22-2014, 01:52 AM
  #40
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Hi,
Some interesting stuff coming soon.
New model from Gernot Bruckmann in collaboration with Andrew Jeskey.
The wing strut bases are screwed on - adjustment should be a lot easier with this .

Brian
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Old 04-22-2014, 03:06 AM
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I was the builder of two of Steve Strickers TOC Ultimate's that he used in the mid eightes with great success. We had very thin wings 9% and very light wing loading. The incidence setup was 2 degrees up thrust, zero, zero, zero. Four degrees of right thrust to hold it straight at low airspeed. Steve always flew with as little mixing as possible and condition switches were not used by him at all. Several competitors couldn't fly without lots of mixing and a condition switch position for each type of maneuver. Each plane is different by design forces, location of the wings and the tail.

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Old 04-22-2014, 03:36 AM
  #42
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Hi Ron,
Interesting.
I have not tried to work it out but I think these 5Kg F3A bipes have an even lighter wing loading that a TOC bipe so I'm interested to read that you were at a 9% section.
Thanks.

Brian
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Old 04-22-2014, 07:46 AM
  #43
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Brian,
We were trying to get the plane to snap on demand. His Sterman was so lightly loaded and with a std thickness airfoil it just would not stall easily. We had to use fuctional flying wires and lots of titainum fittings to meet the weight limit of 10 Kgs back then. Once they removed the weight limit is when we built the larger Extra's in 40 and 50% size in the early nintes as biplanes lost their bonus points. Most people never saw his 50% Extra fly including myself as He had aileron flutter ealry on with the crappy servos we had back then and we couldn't fix it before the TOC that fall and Steve sold the plane right after we got home in 98.
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Old 03-05-2016, 05:43 AM
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Hi,


I am currently building an Ascent Bip from Naruke Hobby. This is basically the same plane Onda used as his A model at the WC 2015 just with the old name Acuracy. I bought a kit for the GP version and have converted it into electric with a hatch at the top as on the Oxai EP version.


I am almost new to biplanes. Had a Miss Wind 50 from Sebart some years back but never measured the incidents on that plane.


When building kits I am so lucky that I have a full size drawing with the planes datum line and incidence for motor, stab and wings. What I am trying to figure out is how the plane will present in the air. If I misunderstand the concept my colour scheme can look like the plane is either flying with the tail low or too high.


The motor trust and the low wing are inline with the fuse datum line. So with this two as 0 degree the top wing will be -1 degree and the stab +0,5 degree. I assume both wings will have to fly with positive angle of attack so the bottom wing will be more then +1 and the top wing will be more than 0 degrees?


Input is appreciated.


I will upload some pictures.


Br,
Henning
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Old 03-05-2016, 05:50 AM
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Old 03-05-2016, 06:07 AM
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Old 03-05-2016, 07:06 AM
  #47
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great looking work! The Naruke Hobbies' kits are fantastic (I have an Ascent monoplane kit). I have not built a pattern biplane since my Sunray in 1980, but I'll follow your efforts with interest.
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Old 03-06-2016, 06:03 AM
  #48
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FWIW.... I'm currently working on a Goldberg Bucker Jungmann. According to the plans it is a 0-0-0 with 1.5 right thrust. It is said that it has no to very little roll coupling so I would assume little down elevator is needed inverted. Time will tell. I'm in the covering stage right now.

Ken
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Old 03-06-2016, 02:33 PM
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Ken, roll coupling is mostly a function of dihedral. Amount of elevator when inverted is a function of CG and incidence.

with wing, stab and engine down thrust at zero, the bipe may not fly as expected. Suggest to add about 1 degree of down thrust in addition to keeping wing and stab at zero. It will clean up the up lines among other things.
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Old 03-08-2016, 03:27 PM
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Hi Henning

The Ascent is looking great.

My knowledge on F3a biplanes is almost zero but I do have a Miss Wind 50. I'm not sure what the thrust is but with the stab at zero the top wing is -1.5 and bottom +1.8. The incidences of the Ascent look a little confusing to me. It would seem that it will require up elevator to fly level. Looking at the plan although it gives +0.5 on the stab the stab outline looks like it has negative incidence which makes more sense to me. There are also two lines that cross in the centre of the stab. The top line which is just below the LE centre and has the 0.5 over it crosses the bottom line. At the trailing edge both lines are well below the stab TE. Maybe I am looking at it wrong but measuring to the datum the stab is negative.

Keep up the good work.

David
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