Rendegade

Bryan, I thought I'd just put this over in another thread before it degenerates any further.

Can you tell us how you've come up with these, and more importantly how you've overcome some of these issues? This isn't meant to be an attack, I'm seriously interested, as I'm sure are quite a few other modellers.

flyncajun

Recently the designer of the Spark e-mailed me and said He liked my Bipe and He was designing a Bipe, and wanted to know my Bipe setup.
I Had a weak Moment and gave a setup to him LOL
So you might be able to pry that one from him, But I cannot just give that info Out anymore. It has cost me 20 Years of my Life, I think it may be worth something.

I figure if you can Buy My designs, reverse engineer it, and just look at the common sense and experience in it, we both win
Every think I do to a design is proven purpose.
Every body knows when they eat a Cake "mostly "what is used to make the batter, and you know all cakes LOOK good ,How much of whats in the batter gives the outcome for the "good" cakes. The chefs never tell what the recipe is for the really good cakes, they would no longer sell the best cakes LOL

Every airplane designed today for competiton by active competitive pilots" Not the knock off look alikes" are worthy airplanes. It is the small details that are missed,what cannot be seen that seperates the knock offs, Competition and understanding of the needs of the airplane in competiton is what makes the really good designs. and they evolve from this. Thats Why My airplanes look like My Airplanes or CHip Or CPLR`s airplanes look like they evolved from a educated Idea. We have a philosophy that evolves from understanding What the goals are.
WE are involved enough and lucky sometimes to see the new power plants available ect. and design around this knowledge before the average guy even knows about new products are being developed around the corner.

An airplane that is not well thought out or designed , starts the chain reaction rolling, and the mixing begins. this mixing seems to be Mystical and we actually like that about it, it gives us endless hours of debate about what it might be. I go out and find what it is, refine it in the next design, and eliminate it. usually when you find the cause for one mix,it is actually the fix for two other problems. they have a way of compounding problems.
We waste our time putting bandades on the sore ,and not curing whats causing the sores. and our new radios actually enable this.
Ever notice every Bip out there has the same wing area ,Why every body copies what they think the other person my know!
I copy myself. and improve on what I know ,When I try to improve on what somebody els knows I fail.

Refinements come from understanding the Needs or Goals of what the Purpose is for the design, Everything done in the design needs to be in Harmony with the Purpose of the design. from the gear to the paint.
Available Power, for the most part, drives the advancement of the design and gives the flexibility in the setup Thats why Props are so effective in changing how a airplane feels , But most can`t feel the good or bad that prop may do to the setup of the design.
I try to design with everything in mind.

Most Guys don`t realize that by having thrust off set in the engine it actually robs power from the prop! this is a small but important detail.

Here is my secret in a nutshell.

Every thing you do the airplane that changes the force required to fly it straight ,causes three other problems (triangulation
This in turn affects Everything and I mean everything , we do to get the airplane to fly without mix. From throw to expo`s
Understanding what percent to make an airfoil,or how much wing area is required to make the aiplane fly without compromising the trim of flight, to how big to make the ailerons ,or how much fin and rudder to use, all contribute to the ability to trim the airplane without mixes.

Then having the skill to seperate these out and find the flaws in the setup, or design ,is what sets me apart ( in my oppinion )
I have had countless students to this philosophy,and very successfull students I might Add
All from a old Coon Ass from down the bayou.

Bryan

MTK

Speaking for myself, If you played around in this game long enough, you've heard and/or read every one of these "fixes, dosand don'ts", several times over. There are others as well....

From personal experience I can say that a rearward CG makes the plane work okay in inverted flight but makes it uncertain in pitch when upright. Throw in anhedral stab with a rear CG and cross wind flying creates a whole nother set of problems.

I've found that stab anhedral does detractsome wing dihedral. Flatten the stab and yaw response is different, all other things equal. I've found that a small amount of down thrust does correct a pitch to canopy in the full power upline. But it can create other issues so I use the technique sparringly. A slight positive in the stab helps correct both an upline and inverted flight when CG is forward, between 25% and 30% MAC

No way anyone will convince me that a heavy model flies better than the exact same design does10-15% lighter. On CG, I tend not to useCG as a trimming criterion. I tend to calculate it'sideal position based on areas, area distributionand moments, and add 15% static margin. There is nothing magic about 15% static margin, it is something that I've settled on with experience.

I love the flightenvelope ofsmall LE radii. Occasionally I used larger radius on the wing LE in particular and have always been disappointed, Add to the list that thick wings create more lift than thin wings. Baloney! Thick wings are sluggish in pattern apps, plain and simple....

I don't subscribe to the tiny wing syndrome that has invaded patterndom. Properly designed, large wings have all the attributes we want plus they reduce loading, which enlarges a model's flight envelope. I don't subscribe to flared rudders or thick TE's. I don't subscribe to canalizers. Dorsals and ventrals, definitely, and not just on fuselages....

I don't think I've ever wound up with a model set at zeros all around. Tried to tweek the model's angles based on need rather than preconceived notions, particularly over the past 20 years as trim technique has been learned and refined. I think that's where Bryan is coming from too

Have never used aileron differential on a pattern model, only trainers with rectangular wings.

I use and recommend high taper ratios in wings, at least 3:1 root to tip. My current design sports 3.4:1. This enables a significant increase in wing area with no down sides in roll response. It also produces greater capability in cross wind.

I use and recommend low TVC (tail volume coefficient). I use TVC in pattern models around 0.6 and it has served great over a couple decades. Some, very few, commercially available models are getting down close to this at present. Most still play in the 0.8 TVC region.Stated simply,lower TVC produces more spritely performance which is super duper in todays schedules

I've found that, in every case where a single prop was turning CCW (front view), for a given and identical amount of aileron deflection, right roll has always been faster than left roll. I've always had to increase left roll deflections to compensate. Having flown Dave L's contra Bravo, I saw and felt that problem go away. This seems to imply that SSS is the culprit

Regards SSS, Bryan and I differ in our opinions a bit; But I'm not sure whether Bryanis actually sayingthat it doesn't exist. I think he believes it does but that he simply doesn't care since his trimming reduces it's effects to negligible levels. I believe that roll response difference is directly attributable to SSS. This could be proven far easier in an E set-up where motor can be set-up to run in either direction. I would love to hear results from someone with an E-plane that is willing to try the experiment.....

smcharg

My Feedback: (1)

Matt, you are exactly right. Bryan and I have had several conversations on the phone based on the other thread. Yesterday, without discussing it with him, I said in that thread , "Sounds to me that Bryan isn't announcing that the spiral slip stream doesn't exist or does exist (leaving the thinking to the theorists) but simply that it isn't a variable that must be adjusted for in our models."

I got a text from him a little later saying "Bingo"

I, for one, really appreciate thinking outside the box. People can learn a lot if they stop and listen with a clear mind and without prejudice. They don't have to agree but they can certainly form their own opinion instead of just following the masses. Right or wrong, y'alls knowledge is gold. Thank you for that.

Scott

MTK

I'm buying a Shinden, not to reverse engineer it, that's not necessary.Rather, to gassify it and continue to learn. The Shinden has a few features that are in line with my design philosophy and goals, in a ready made package that I don't have to build or break the bank. $1500 is not particularly expensive for such a model.

On the other hand, what Oxai wants and gets for their stuff is absolutely crazy. They don't fly 3X as well as other stuff. Hard pressed to fly 1X as well.

Doug Cronkhite

My Feedback: (34)

Hehe.. fun talking points here for sure.

Thick symmetrical wings don't create any more lift than thin, but they do create more parasitic drag. Depending upon the airfoil chosen, they can also increase induced drag. Sometimes this is desirable, sometimes not.

Sharp leading edges do ABSOLUTELY NOTHING to the pitch sensitivity of a wing section. It does lower the parasitic drag SLIGHTLY, but it's primary benefit is a sharper leading edge radius will cause airflow to separate more quickly than a blunt radius. That's it.

Heavy is NEVER better. A heavier airplane will be slower to bounce around in the wind, but once moving, that inertia then works against you taking longer to damp that movement.

A 0-0-0 airplane will always fly with the fuselage and tail low relative to the direction of a flight, assuming the wing section is symmetrical. Simple reason being is that a wing section requires angle of attack to generate lift.

As for SSS causing your airplane to roll more quickly to the right.. Torque should be working for you when rolling to the left, allowing the airplane to roll more quickly left than right. The Sopwith Camel was a perfect example of this, albeit reversed since its engine turned CW when viewed from the front. It would roll (and turn) VERY quickly to the right, but was TERRIBLE rolling and turning left as a result of torque and gyroscopic precession.

Thrust arrangements in the engine generally control what the airplane does in an unloaded state, such as in a vertical upline, HOWEVER, there are caveats to this as well. A thrust line of 0-0 works just fine IF your airplane never changes speed in up lines from its speed in a static level flight state. If your airplane slows down though, then the forces at work in balanced 1G flight, begin to cause issues in the vertical. There is no magic bullet that will work with all force arrangements when it comes to thrust settings. For any given design, there will be differences. I've never put any down thrust into a mid-wing, mid-stab airplane. For my 46% Ultimate Bipe, I needed UP thrust. Same for my original 35% Cap 232 which had a high thrust line relative to the wing, with a high stab. It required 1.5 degree of up thrust to draw straight up lines.

My basic rules have been, Thrust controls up lines, Trim controls down lines. Bryan is dead on the money though when he says that changing one thing will always affect other things. That's absolutely true. This is why it's so important to make ONE CHANGE AT A TIME, and then re-test.

RC_Pattern_Flyer

My Feedback: (1)

You said outside the box.

Design by Mark Hunt

mjfrederick

The Rebel Alliance might sue for copyright infringement.

OhD

Are you airplane designers/trimmers going to put right thrust in this design (reversed motor rotation) and why?

Jim O

tuny

From My experience:

- anhedral stabs look cool!, thats it, no changes in anything, only a pain to set up straight.
- moving the stab incidence is the exact same thing as moving the elev trim, this does nothing in the trimming process, after the plane is trimmed adjust the stab to ged rid of any elev trim.

Tuny

vbortone

My Feedback: (2)

I agree with Tuny. I did it many years ago. Check the pic. Flew the plane with both and never felt any difference. It will be interested if someone guess what is the name of that plane.

Rendegade

Looks like a Tornado (too big to be a Bullet), obviously with an anhedral stab.

vbortone

My Feedback: (2)

It is really the bullet. Very nice flying pattern plane. ST 46 with 0% nitro. Kraft radio.

tuny

Most important, that pic is in Venezuela!!!!

vbortone

My Feedback: (2)

Correct. Field Tucape still in use. City San Cristobal.