rgreen24

My Feedback: (6)

Jim, for giggles try adding the stab fences to see if it helps in yaw

mithrandir

My Feedback: (2)

I kinda feel like my Eclipse needs more vertical... maybe I will try some stab fences or a bigger sub-fin?

OhD

I suspect that if there is an increase in lift for a given angle of attack it is because it prevents the air from spilling over the top of the fuselage as Alex and others have described. Sounds like we need an "I" beam cross section fuselage. How about a Hiperbipe with the top and bottom of the fuselage wider (hanging over like a roof does) than the normal rectangle-cross section. Then put twin verticals on it like a B-25 to get the yaw stability?

I believe Alex also showed it did reduce the span wise flow on the vertical so I guess the answer is both.

Jim O

OhD

Robert, the fences really improved my Gaudius and Tony F swears by them, so I'm sure they would help but I hate to mess up the beautiful Oxai finish. I've been trying more and more Expo (I'm at 82%) and next I will try less throw and a more reasonable Expo.

Jim O

rgreen24

My Feedback: (6)

I know that Oxia makes a great finish, however you can put the fences on it and make it look just as cool

OhD

I meant to say put twin verticals on it, but at the edges of the fuselage not at the ends of the stab like a B-25. I kind of remember seeing Cliff Weirick flying a model of one of these back in the 1960s or 70s and some great knife edge flying.

Jim O

patternflyer1

My Feedback: (11)

My opinion, make it larger than the CA one, more like a partial bipe... Lower than the top of the vertical stab or you start blanking that out. I think that the can makes the vertical fin see the air more closer to mid rudder than without it. I do feel positive or negative makes a big difference due to where it puts the air over the vertical stab.

I really don't see that a contra fixes a lot of issues. It adds a lot of issues. Sure, it may fix some, but I haven't seen where there is a 0-0 setup with no mixing with a contra yet. That would tell me the contra fixed things. Otherwise, it's a band aid, like all other gadgets IMO. Although I haven't flown one or set one up to know so I could be wrong.

C

serious power

' Although I haven't flown one or set one up to know so I could be wrong. '

Yes you could !

Brian

Malcolm H

You beat me to it Brian!

Malcolm

serious power

Malcolm,
Yes, why someone would expect the propulsion device to negate the power of gravity in all aspects is beyond me .

Brian

RC_Pattern_Flyer

My Feedback: (1)

Biplane or EXTREME channelizer?

n233w

Absolutely Love it! Bring it on, Jules Verne!

Bill

Fixed Wing

Flown by Captain Nemo...

Jetdesign

My Feedback: (8)

My money is on this guy.

OhD

I flew the Axiome with and without the channelizer yesterday. The object was to determine if the channelizer affected the yaw to roll and pitch coupling and the required mix during knife edge flight. With the channelizer I had required a little yaw to roll mix with left rudder knife edge and none with right rudder. I had also required a slight amount of down elevator with both right and left knife edge. I also decided to put the mix on a switch so I could test it with and without the mix.

I was expecting to see the plane pitch to the belly without the channelizer but had no idea how it would affect the roll. In the limited time of one flight, I concluded that I saw no effect on knife edge roll or pitch coupling with rudder. It did seem to require more rudder especially on right rudder knife edge suggesting that the channelizer did add to the lift of the fuselage in knife edge. I didn't fly it enough to determine how it affected yaw in the various pushes and pulls (it didn't seem any worse) but I would guess that stab fences would be a lot more effective solution to improve that characteristic. I put it back on and flew with it the rest of the day because it looks like hell (up close)without it.

Jim O

Rendegade

I have often thought that I'd like to try flying my mythos without the cannalizer and see what I get.

With that said, I don't know if adding stab fences would necessarily have the same effect, I would assume that having the canaliser where it is would change the centre of pressure of the fuselage in a more forward position (reducing 'spanwise' flow around the fuse) requiring less rudder to hold a KE

While adding stab fences may increase the effectiveness of the rudder, your CP may still be aft and require a very powerful rudder to hold it.

Not sure, food for thought anyway.

apereira

Some years ago, I lost the T-Can in flight on my first Osmose, and the airplane flew like crap, it need double the rudder to do the same with the T-Can, and the lesser the couplings the better, and the coupling got worse, of course the airplane was set up already with the T-Can, and I did not change anything, just got the T-Can back in.

Regards

sleeping

I'm sure have all read Brian Herbert's 'triangulation method of trimming'. Regardless of whether we subscribe to it or not (I do, but that's just me), there is one point he makes which I cannot ignore: "no drag is good drag". Exception to the rule, as there always is is your main wing profile, prop braking and the flared trailing edges of the rear stabs.

My point is that introducing a canalizer is another airfoil that has pros & cons as listed herein and all very well justified. But overall it must be said it makes the aerodynamics of the frame more complex and harder to understand. If in a very hypothetical scenario I banned CPLR from using a canalizer, besides the fact we do actually have to fly the plane, I think he'd find a different design.

QQ's spilt aileron? People have asked a number of times what benefit would come of that and there's been no response. Given the judges are so critical on snaps, many wing designs (the Spark a perfect example) have moved their MAC point / overall lift of the wing wing closer in. Perhaps? QQ is getting around this by using 'both elevators' in snaps and therefore allowing him to retain a large surface area on the main wing; again, as noted prior.

i've tried to be as neutral as possible !! in my thoughts, as I'm really hoping to for some responses back from JAS, Tony and everyone else involved.

cheers
DA

cartercg

I have played with installing stab fences, wing tips fences and a t-can. I think the benefits depend on the airframe. One thing is for sure, they are not a fix for a poorly trimmed airplane. I have spent considerable time applying Bryan's triangulation trimming, with great results. On my Peridot the t-can made a very noticeable difference. It made a very good plane with very little mix even better.

When I set up the rud to aileron mix I fly the plane on KE with somebody taking the reading of the stick position that I have to hold to maintain KE. My Futaba 18MZ gives me this value. I then set a point mix at the value, and can then set the aileron mix I want at exactly the right point. I also set up a point for the sort of rudder throw I need for KE loops. This helps when setting up the mix settings as I can change the mix for say KE without effecting the mix at the rudder I use for say hard KE loops.

Without the t-can I needed to hold 20% rudder stick to hold KE. After installing the t-can this dropped to 13%. That is a very significant reduction. The plane also held KE with a noticeably flatter angle. Net result is flatter rolls, easier KE loops and easier integrated rolling stuff. I installed my t-can zero deg to the main wing. I needed to move the CG back slightly. Rud to ail and rud to elev mixes needed to change slightly, but these mixes were already very low.

regards
Clint

TerryTill

I've been coming back to this thread just to look at this plane. It looks amazing.
Please let me/us know how it flies.

Terry

apereira

As CPLR told me once, he said "I do not know why is it everybody is not using it", to me that is enogh, and previously commented by Clint it has clear benefits.

OhD

It sounds like we all agree on its effects on knife edge flight. More lift for a given angle of attack so it takes less rudder. If rudder to aileron mixes are low to start there is little change. I believe Alex V has shown why this happens and has proposed a better solution, that is, a longer fence to channel the air in a "chord wise" direction if you think of the fuselage as a very low aspect ratio wing. It also seems like CPLR has gone that direction with his new design by decreasing the aspect ratio of his "canalizer".

In French canalizer sounds like cana lee zee. To channel, tunnel, marshal, duct.

Jim O

Alex Voicu

I think the solution i proposed (for those who are not familiar with it, the fuselage strakes and fin fences in the image below) needs to be tested on more airframes before saying that it's better than the canalizer.

I noticed the same benefits with the canalizer as mentioned by other pilots in the posts above, but the fuselage incidence in KE horizontal flight didn't change significantly. I would say that in general the effect of the canalizer was roughly equivalent with the addition of the fin fences, at least that was my impression when flying the plane.

Adding the fuselage strakes though really made a difference; the fuselage incidence was reduced dramatically and the fuselage now sits almost horizontally in KE flight. Sure, a small angle is still needed because the fuselage is symmetrical and as we all know, a symmetrical airfoil needs a little incidence to produce lift, but KE seems a lot more efficient. The first time i tried the fuselage strakes, i rolled the plane in KE position, while at the same time moving the rudder stick to the position i was used to for holding KE flight, and the plane actually started a KE loop. Even with 80% expo on the rudder, KE loops need very little rudder, i don't think i ever used more than half of rudder throw even on the exits and i need to pay attention not to make them too tight.

The rolls also benefit from this, they look a lot more axial and very little rudder is required. My main concern is not to over-correct with rudder.

Anyway, i think most pilots will be reluctant to use the fuselage strakes because the plane looks unusual with them, but i think the canalizer also met some resistance when it was first introduced.

sleeping

Perhaps I'm over-thinking this so let me know!

Your flying when it's a perfect calm day; no wind at all.
You complete one side of the box and now your flying horizontal at the bottom of your box and you are 100% at your preferred speed.
you then pull into a vertical line and open the throttle to maintain your speed. But as the plane loses it's momentum and relies more on the prop thrust alone, just how much does your airspeed change over your wings, T-Cans, etc? Your control surfaces are less responsive, so how does this affect all the trimming / adding of additional surfaces that you've made? Rolling loop ?

To summarise, we trim for normal, Ke, snaps, etc, etc, but is there any noticeable behaviour when you have more thrust / less momentum?
And to round it out the 'reverse' on down lines?
cheers
james