HorizonHobby.com Shop our Airplanes Products Shop our Surface Products
Thread Tools
Old Feb 02, 2016, 11:37 AM
Vince Caluori is offline
Find More Posts by Vince Caluori
Registered User
United States, WA, North Bend
Joined Dec 2002
202 Posts
Discussion
Aerodynamics and design of F3P models

I’d like to start this discussion with the canalizer. ( the small wings we attach to the upper and lower fuselage above/below the wing)
I have not seen a contemporary design that doesn’t include them.
Even Devin added some to his Annubis at the World Championships. (hope he comments).

The point is what are they doing for us and why? If we knew that we could discuss area, aspect ratio, vertical and horizontal position relative to the wing, and incidence angle with respect to the wing.

Some explanations i have seen include that they are a way to add lift area without increasing the wing span which would affect roll rate. The more lifting area the slower we can fly.

Maybe they serve as end plates for the fuselage. The fuselage in our models is definitely a lifting surface when we knife edge. End plates would increase the effectiveness of the fuselage

The F3A guys say the T-canilizers they use totally change the way their airplanes handle particularly the rudder response but also in roll but they are 3 dimensional ships and not flat.

So what function or functions do they serve and how do we optimize them?

Opinions? Facts? Guesses? Theories? How big should they be?
How long should they be? What aspect ratio should they be? Should they have any incidence?

Does anyone have any real data?
Vince Caluori is offline Find More Posts by Vince Caluori
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 02, 2016, 01:11 PM
Free is offline
Find More Posts by Free
"Free" in Christ! #F3P
Free's Avatar
United States, CA, SF
Joined Jan 2012
1,072 Posts
I would love to hear about not only canalizers, but also about the general design process that goes into designing a world class model.

Personally most of my designing comes from trial and error and basic aerodynamic principles, but I would love to start designing on a more scientific level.

I'll be watching this thread and hopefully we can get some insight into the design of these amazing aircraft.

Free
Free is offline Find More Posts by Free
Reply With Quote
Old Feb 02, 2016, 03:59 PM
Finnspeed is offline
Find More Posts by Finnspeed
F3A Team Finland
Finnspeed's Avatar
Järvenpää, Finland
Joined Nov 2005
1,067 Posts
I'm not a designer but I do know that in F3P (the models I know about) the canalizers are meant to improve knife edge characteristics. I think the ultimate goal is to be able to fly beautiful rolls (no wobbling or huge corrections) and particularly help if a move includes knife edge loop sections.
Finnspeed is offline Find More Posts by Finnspeed
Reply With Quote
Old Feb 04, 2016, 09:49 PM
Vince Caluori is offline
Find More Posts by Vince Caluori
Registered User
United States, WA, North Bend
Joined Dec 2002
202 Posts
No wobbling in rolls with minimum corrections and capability to make knife edge loops are two interesting design requirements.

In a rolling maneuver we therefore would like the fuselage lift to be the same as the wing so that we would not need to make rudder corrections, thereby increasing the angle of attack of the fuselage to compensate for its lower lift.

In the knife edge loop we would want to increase the lift of the fuselage with respect to it’s angle of attack. Lots of rudder applied to change the angle of attack.

Canilizers or end plates can be effective in both cases.

End plates effectively increase the aspect ratio of the surface. Higher Aspect ratio means more lift per degree of angle of attack.
Here are data that show the effect of the height of the end plate/span of the surface and the area of the end plate with respect to the area of the surface: fig 15 Hoerner Drag.

Clearly if we are relying on the end plates we want tall end plates with lots of area. Tall in this case means end plate span with respect to the fuselage depth to the wing.

What should they look like? I’ve seen circles, high aspect, and low aspect versions. Here is some data; Fig15 Hoerner Lift.

The text that goes with this data says: The circular plates provide a higher effective aspect ratio than equal area rectangular plates. Regarding the triangular plates the one with straight leading edge seems to be better for lift while the one withe point leading causes less parasitic drag. Reduced to the same area ratio,plates between c and d are expected to be optimum. Of course in our F3P ships weight is critical and the circular end plate will be lighter. Less circumference = less carbon. (maybe Alexy is right as he usually has a circular or semi circular canilizer!)

Of course, This test data is based on a real wing and not a fuselage like we are dealing with. If we make a SWAG that the fuselage is a very low aspect wing than losses at the tips or edges of the fuselage could be high and might accentuate the benefits of end plates.

I just watched Jurgen’s video of Nicolas Detry’s flight at the swiss championships which was great and his airplane has no canilizers. Maybe he decided to save a couple of grams! Filo Materazzi also flew a great flight and his ship has his traditional high aspect canilizers but with “ventral” fins extending a short way above the canalizers. Both ships are beautiful and looking very light.

I think i noticed that both ships had smaller wings; maybe that gets their fuse area closer to the wing area?
Vince Caluori is offline Find More Posts by Vince Caluori
Last edited by Vince Caluori; Feb 05, 2016 at 06:06 PM.
Reply With Quote
Old Feb 05, 2016, 03:18 AM
Jurgen Heilig is offline
Find More Posts by Jurgen Heilig
Registered User
Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
18,846 Posts
Quote:
Originally Posted by Vince Caluori View Post
... Does anyone have any real data?
Hi Vince,

I don't think that anybody has real data. Current F3P models have moved into an area of very low Reynolds numbers.

In order to get real data, you would need to run very low speed wind tunnel tests. Alternatively you could experiment with various shapes and forms on the same model and watch/evaluate the results.

Jürgen
Jurgen Heilig is offline Find More Posts by Jurgen Heilig
Reply With Quote
Old Feb 05, 2016, 02:37 PM
Vince Caluori is offline
Find More Posts by Vince Caluori
Registered User
United States, WA, North Bend
Joined Dec 2002
202 Posts
Jurgen,
Your comments are to the point and I couldn't agree more.

Your event films/photos and reporting of the specifications of the airplanes are therefore priceless. That is true especially for those of us in the USA where F3P is not at the same status as in Europe and where we have to travel for days by auto to attend each others rare contests.

Vince
Vince Caluori is offline Find More Posts by Vince Caluori
Reply With Quote
Old Feb 05, 2016, 11:17 PM
Vince Caluori is offline
Find More Posts by Vince Caluori
Registered User
United States, WA, North Bend
Joined Dec 2002
202 Posts
I looked at Julien Hecht's flight at he Swiss Championships and his airplane looked a lot like Detry's. Except he had one canalizer mounted below the fuse and none on top.

Would be great if they shared a little data with the rest of us!
Vince Caluori is offline Find More Posts by Vince Caluori
Reply With Quote
Old Feb 06, 2016, 04:34 PM
AJWoods is offline
Find More Posts by AJWoods
Aircraft Designer Guy
AJWoods's Avatar
United States, CA, Santa Clara
Joined Jul 2005
1,764 Posts
Not to over simplify, but this one picture pretty much sums why we end up with all sorts of extra devices on the fuselages.

Even if we fully balance the area of the fuselage with the area of the wing, since the fuselage has a MUCH lover aspect ratio, it will need to be at a higher AOA to generate the same lift. All these end plate effects are to make the fuse behave as though it had a larger aspect ratio, or drive to a span efficiency over 1.

One solution would be to substantially increase fuselage area so that lift from the wing = lift from the fuselage at the same AOA, this would provide for the most axial slow rolling maneuvers, without changes in aircraft pitch angle throughout the roll. The other option is to just match area's and aspect ratio with non-planar wing layouts. I experimented a bunch with this, and you can build remarkably neutral aircraft, but they do not "present" as well, since they just look weird. http://www.rcgroups.com/forums/showt...1567447&page=2

Also made a big balsa version this summer. http://www.rcgroups.com/forums/showthread.php?t=2467257

-Adam
AJWoods is offline Find More Posts by AJWoods
RCG Plus Member
Latest blog entry: Star Wars Lambda Shuttle
Reply With Quote
Old Feb 06, 2016, 04:43 PM
AJWoods is offline
Find More Posts by AJWoods
Aircraft Designer Guy
AJWoods's Avatar
United States, CA, Santa Clara
Joined Jul 2005
1,764 Posts
One other addition that's been working it's way into the top tier models is gentle sweep of the wings. Wing sweep contributes to effective dihedral, as shown in the attached chart. By gently sweeping the wing, the plane will be closer to (or actually) spirally stable, upright or inverted. Making straight line segments look more locked in, without any need for pilot corrections.
AJWoods is offline Find More Posts by AJWoods
RCG Plus Member
Latest blog entry: Star Wars Lambda Shuttle
Reply With Quote
Old Feb 07, 2016, 06:34 AM
Ampbomber is offline
Find More Posts by Ampbomber
Registered User
Ampbomber's Avatar
Michigan
Joined Aug 2002
383 Posts
Can someone explain how mounting the cans perpendicular to the fuse helps change the fuse AOA? Or am I missing something? Seems that they would affect overall wing area and lift.
Ampbomber is offline Find More Posts by Ampbomber
Reply With Quote
Old Feb 07, 2016, 07:38 AM
pmackenzie is offline
Find More Posts by pmackenzie
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
Joined Dec 2002
18,663 Posts
Quote:
Originally Posted by Ampbomber View Post
Can someone explain how mounting the cans perpendicular to the fuse helps change the fuse AOA? Or am I missing something? Seems that they would affect overall wing area and lift.
The theory would be that they act like wing tip plates and increase the effective "span" of the fuselage when it is knife edge.

I think they might be a bit to small to do that. Look at the ones used on F3A models, they are a tiny percent of the fuselage length.

But they might keep the flow straighter as it hits the rudder?

Or perhaps it is some combination of the two?
pmackenzie is offline Find More Posts by pmackenzie
Reply With Quote
Old Feb 07, 2016, 07:46 AM
Ampbomber is offline
Find More Posts by Ampbomber
Registered User
Ampbomber's Avatar
Michigan
Joined Aug 2002
383 Posts
Thanks. Would any anhederal or dihederal work better?
Ampbomber is offline Find More Posts by Ampbomber
Reply With Quote
Old Feb 07, 2016, 08:17 AM
pmackenzie is offline
Find More Posts by pmackenzie
I don't want to "Switch Now"
pmackenzie's Avatar
Toronto (Don Mills), Canada
Joined Dec 2002
18,663 Posts
They are usually flat, but another question is what angle of attack to mount them at
The Elanor I fly has them at 0-0, but I think the Trivia has them mounted with the leading edges closer to the centre line.
The ones on the Trivia are much larger than the ones on the Elanor, so that might have something to do with the difference.
pmackenzie is offline Find More Posts by pmackenzie
Reply With Quote
Old Feb 07, 2016, 08:45 AM
Ampbomber is offline
Find More Posts by Ampbomber
Registered User
Ampbomber's Avatar
Michigan
Joined Aug 2002
383 Posts
Yep, flat is probably easier. I'll work with probably 7.5 " d and round. I'll be thinking about it as the build goes on and more info arrives.

Thanks
Ampbomber is offline Find More Posts by Ampbomber
Reply With Quote
Old Feb 07, 2016, 10:41 PM
Vince Caluori is offline
Find More Posts by Vince Caluori
Registered User
United States, WA, North Bend
Joined Dec 2002
202 Posts
Pat,
Your observation that the Trivia had incidence compared to the wing was interesting. The Armonia kit from Techone had almost 3-4 degrees of incidence. Leading edges high from the wing. It is a locked in knife edger!

I asked Signore Materrazzi what his thinking was but could not get an answer.

Vince
Vince Caluori is offline Find More Posts by Vince Caluori
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion F3P model control horn plans harry silver Indoor Pattern/F3P 2 May 18, 2015 11:05 AM
Sold Zaic, Model Glider Design; Simon, Model Aircraft Aerodynamics RCGrouSS Aircraft - Sailplanes (FS/W) 4 Dec 12, 2014 11:26 PM
Sold Zaic, Model Glider Design and Simon, Model Aircraft Aerodynamics RCGrouSS Aircraft - Sailplanes (FS/W) 1 Dec 12, 2014 05:05 PM
Question The most aerodynamicly efficent design for an RC plane? Drunkskunk Electric Plane Talk 77 Dec 17, 2013 07:57 AM
Discussion Design your own F3P model Ruud_NL Indoor Pattern/F3P 1 May 04, 2007 06:23 PM