Hi Todd
Thanks for the shout. I don't know that I will be flying in competion but I have a "Hankering" for something pure to fly!
Say Hi to your Dad for me.

LOL Yeah Doug,
It increased stability so much now, I can do a knife edge loop on just the rudder trim!
I just love making that stuff up,
Oh but then,
I tried the t-can, but it gave the rudder so much power I took it off because I was able to do knife edge loops with my mind.[sm=confused_smile.gif]
thats why I went back to the strake it took all the rudder power away
Also,the t -Can made the airplane a mix free bi-plane and I didn`t like that about it.
Bryan

Hi Brian
Thanks for the quick reply. As I told Todd I don't think I will be flying competitively, but I never say never! I have not flown "competitvely" in over 15 years!
I really like the looks of the Valiant and the quality of CARF aircraft. What was the lacking rudder response or feel"" that made you go to the "strake?"I have narrowed my search down to your Valiant or the CARF Yak 55 2.6 m. I am leaning toward the Valiant. I noticed on the website there were no Bldg Pics or Bldg. Instructions. Are they now available and included with the plane? I did read the Valiant build thread on RCU.
Great talking to you and thanks again for the reply.

Dick Mundee

Hi Dick ,
I hope you will pop up and fly with us, it would be good to see you again. Once you fly a modern pattern airplane you won`t be able to help yourself ,LOL
The build instructions are finished and will be added in a week or so to the site, along with the Strake instalation instructions.

I added the strake after Jason requested I design a T-Can for the Valiant and give him some feedback (he really likes it on the Integral and wanted me to build one and test it)
Any one who knows me knows,I don`t like add ons and have refused to use them because mostly they are used to correct trim problems,But at Jasons request ,,I made three add on versions to test,
A simple Fin like Dave Lockhart uses, it works very well for him,
a 5" T-can and ,
The Strake.
I tested them on a 10mph wind day, two flights each.
The Fin helped a little but not very much ,,it did not have any neg effects however.
I then put the t-can on I was surprised it was set to zero inc. it did give me some rudder authority But no adverse mix or trim needs I flew it for 2 flights through the pattern as before and never touched the transmitter trims.
Next I added my strake I put it on whithout the horizontal stay piece for two flights ,on take off, I could already tell the improvement. The airplane was so solid ,it felt like the airplane was pulling a parachute the stability was unbelieveble , I flew it for two flights through the pattern.
The biggest improvements was in the stall turns ,and the figure m rolling half loop element the rudder power was greatly improved along with stability in yaw.
I added the horizontal stay piece it was added because the first strake was made of Depron and taped on, I was worried it would come off so it was added for reinforcement.
I liked the way it looked and it gave the Strake good stability,so I left it on. it seems to give a little more effect as well.

the improvement is most noticed in the winds, and the snap,and spin exits,it keeps the airplane rock solid and really locks the exits.

I don`t believe in the VooDoo Crap with add ons and I`m all about testing , I also test and retest for the Data. this strake is the most improving find I have come across since I started designing Pattern airplanes 25 years ago.
Jason dragged me into this ,I thank him for the experiment. I started out A SCEPTIC myself, now,
I would not fly without it.

In a pattern design the bigger the rudder and fin the harder it is to make the airplane snap and spin clean, it just makes the airplane too stable this devise, gives you the stability of a very large rudder and fin without the poor results of the overstability.

Hope to see you around the trail
Bryan

Hey Brian
Thanks again for taking the time to explain the whole process as relates to the strake. I am sure that your explanation settled a lot of uncertanty related to the strake device, it made a lot of sense.. I will let you know what I decide.

Dick

Any time Bryan, u know I like to change things up (don't forget the fish )

When I get back from the WRAM show (brrr NY is gonna be cold) I'll post my throws for the Valiant in both threads.

Time to board for NJ

ahh ! the Fish
I cant forget! lol
Bryan

Bryan,
I was thinking for a while on how to improve knife edge flight and came up with an idea similar to yours, but maybe not quite as simple. I have a feeling that your strake in front of the fin may be acting like a simple 'winglet'. If you look at this CFD image from Alex Voicu's thread - http://www.rcuniverse.com/forum/m_89..._2/key_/tm.htm (hope he doesn't mind me using it) you can see that the higher pressure air under the fuselage is leaking around the top of the fuselage and is being wasted. As the tops and bottoms of fuselages are usually nice and rounded, that helps the air to leak nicely from on side to the other in a sideslip (such as knife edge). Adding a simple strake like that could (in theory I suppose) help improve the fuselages 'lifting' efficiency?
But then again, it would probably amplify the effect of a cross wind?

Hi Robert
I don`t claim to be a aerodynamist, I have too much common since, Hell I can barley spell it
If you want to improve Knife edge flight Move the c/g forward and increase the wing inc. it`s just that simple Trust me.you will get power and perfect control.
however, in my testing, and I do too! much,lol the Strake makes the fin and rudder more effective in yaw Control, from static, to full throw.better than anything I have tried including an increase in Fin/rudder size.
designing a Pattern plane,The fuse size always dictates rudder power, the fin size,and airfoil, dictates Yaw control. rudder is the smallest factor.
however your observation may have some merrit

I used to shoot Archery , back then I noticed when the arrow was trimmed correctly ," to shoot the most consistant,"
(we did this with Fletch and different weight tips ) they would always shoot the best in the wind as well.
in other words, if we had to shoot in a cross wind the arrow would always fly into the wind so we had to adjust downwind But it was always controlable no matter how stiff the wind was. Fuse size Never effects wind flying ,,only trimming does.

A Competition pattern airplane, When set up and trimmed Correctly! will do the same thing ,So, I added "Fletch" to the fuse,
and the c/g was perfectly adjusted for consistant yaw performance before hand (over simplified) so, the out come is what I`ve been explaining.

Just remember, if you have an airplane that drifts downwind I call it sliding, or skidding,and is hard to keep on line,in the wind in all attitudes, your airplane is not set up correctly.Any one can trim an airplane to fly in calm conditions , the wind trimming is what sets my system appart from the rest ,,,consistancy and reliability,in all conditions ,no surprizes. With my designs and trimming methods the airplane will attack the wind on its own, in any attitude verticle, horizontal,ECT.
CG too far back is the only reason you will have to use a throttle to rudder mix for example. or rudder into the wind yourself,it`s as simple as the arrow experiment.
We put too much Stock in fuse shape,wing profile rudder size ,,in fact it`s hard to tell our planes appart except for paint schemes,
has anyone found the magic airfoil or wing platform no one knows about ,,,pure fluff.
The fuse shape has so little effect in the big picture, If the designer concentrates on Trimming he will learn more about tweeking the design than a text book could tell him ,like about where to put the center of pressure on his fin.hog wash most anything will work the same as any other.
When you can trim the aiplane to fly perfect with no mix only then will you be able to improve the design ,,untill then you are working on false pretenses and blame what is a trim problem on a design flaw ,, Hense there is no improvement only confusion and fairy tails to explain away why a airplane needs 3.5 right thrust and 2.5 down thrust for example. or why Gyro effect is the reason we need to use a rudder to throttle mix. and 5 mixes are required to fly it.


Always remember,Wing Incidence. controls where to put the CG. to set up a "pure" pattern setup.
The less inc. the furthur back you run the CG V/versa. the rear setup is where the snowball begins.
Most Stabs are too big and most fin/rudders are way oversized there is more problems being generated from these two area`s than anywhere else ,,Excluding wing inc. which is the reason for the latter in a poorly trimmed and thought out design.

So don`t put much stock in a chart, or the test books No one at Nasa has ever designed a mix free Pattern plane and most data derived from the text books lead to poor designs and confusion and a continuation of the same ol`

Sorry I don`t know why I was so long winded
Bryan

Hi Bryan,

Interesting trim notes for sure. Its not often that one plane gets 3 different trim devices back to back. Did you try a knife edge loop with each configuration? I ask this because with today's fuselage volumes, the "mix" needed for only knife-edge flight is often very different that that needed for higher rudder inputs. The knife edge loop gets to check higher rudder input, power-on, power-almost-off. If so, what was the effect of each device? great notes.
Thanks,
Jim

Hi Bryan, completely agree with you're trimming. We were taught a lot of flight mechanics and it's easy to under-estimate it's importance, especially for pattern planes. I've always prefered aerodynamics though and always found these add on gadgets and how they work very interesting.

Actually Bryan I think I was agreeing with you.. Perhaps it's a terminology thing.

Do you consider the strake to be the dorsal fin, or the horizontal flow fence? The dorsal fin would most certainly improve the yaw stability. That makes perfect sense. The horizontal piece making the rudder more powerful also makes a lot of sense too, as it's keeping the air from flowing down the span of the vertical fin instead directing it straight over the rudder, improving it's lifting capability in the chosen direction.

One thing you hit on that most people miss is rudder power being a function of fuselage size (more accurately its ability to generate lift in the yaw direction).

Bryan is right on the money on this issue. What is THE right size for a horizontal or vertical stab? You'll get different answers for different types of flying.

The stab and wing relationship is straight forward to determine. A stab that is about 1/3 the wing area makes a base for a great trainer. For a good aerobat that's just too stable and one wouldn't be happy with the overall flight envelope.

But the tail moment must be considered as well. Some smart folks in sailplane circles have devised a convenient calculation that considers the wing, stab, tail moment and wing MAC. It's a ratio of stab/wing areas X tail moment/MAC lengths. It's THE driving calculation for pitch stability and it has a name....Tail Volume Coefficient. Many sailplanes deal in TVCs less than 0.4. Their wings are more efficient than everything we fly in pattern so going that low on TVC makes for very efficient flight.

For pattern, I've seen TVC greater than 1 for some planes, meaning much too stable in pitch for efficient aerobatics. Great for trainers though. My designs tend to hover at TVC closer to 0.6, making for very spritely performance around the whole envelope.

Lately, the trend has been to smaller wing areas with no adjustment to stab area. Guess what...these are more stable in pitch and are actually countering the very thing the "designers" are trying to do. The results will work but at lower efficiency of control command. This simply means that servos work harder to achieve the desired goal. Yeah I know some will argue "I love the way my XYZ snaps". I can only say fine.

Similar calculation can be done for the vertical ratio of areas and moments...it's just trickier because a fuse gets in the way. You need to do some estimation of where the nose area ends and tail area starts. If you want to make rudder more effective don't automatically add rudder area but consider fuse area increase around mid ships. OR do as Nat did and add a dorsal and ventral strake at midships. Also addition of a smaller dorsal just in front of the fin improves the rudder's ability to pivot the tail in yaw. It tends to concentrate the center of pressure (in yaw) closer to the fuse center line. There is almost no moment to speak of vertically so there is minimal adverse effect to this addition

Folks, Nature has examples of dorsals fins all over, just take a closer look. Take the dorsal fin off a shark and see how the fish turns....

Understanding the Vertical and horizontal TVC is fundamental to what we do in pattern. That's a great place to start a design. There's an awful lot more of course but the rest of the details are trimmings to the tree

MattK

Thanks Matt, Great work on the #`s


Hey Douge just having a little fun, the Strake and Dorsal are one in the same, the horizontal diverter does have a little effect I only used it to stablilize the strake because it was taped on But I like the way it looked so I added it to the finished design.

Jim
my Valiant did not have any mix at any point in the knife loop before or after I added the the three add ons if the c/g was correct.
All devices worked with no mix after adding them ,if anyone tries a add on device to fix a problem, they will probably add two or three problems some where else.They should only be used for enhancement, if it makes the airplane require mix ,the trimming process was not finished before it was put on.
I did add a couple more diverters to the top of the rudder and that addition added a roll coupling at the bottom of the loop and did not add to the effect of the device. so I removed them.

Trimming for knife edge mix is the most important trim process it trumps all other aspects of trimming ,when you get the knife edge ( Left rudder )to "no Mix" it will improve snaps,spins,and rolling maneuvers because the airplane can work in all attitudes with no vices. But unfortunatly most just adjust the cg to make the 4 points and slow rolls easy without any wing adjustement then, Just Mix the knife edge out.
To have an airplane that has no knife edge mix , will heal almost everything else bad the airplane displays if the design is sound.

I drive the Manufactures Crazy changing my dihedral during testing by 1-2 mm and moving wings up and down by slight amounts ,,,adjusting inc. ect
CARF has been Great with the development of the Valiant as was Oxai ,they just did what I asked and together we tweaked all flaws out.
The designer has to do his homework so the modeler has less work to get it to fly perfect.

In France in 05 Chip was discribing the problems he was having with his Bipe to me , rudder to throttle mix, hard to precisly control rolling circles , and some other issues
I told him he was tail heavy just from his description and watching him fly.after arguing some, he eventually moved his battery forward and helped his issues ,and told Me Damn Hebert! I hate it when your right, But only after he convinced me to reshape his fin trailing edge and rudder size to fix the problem, it did nothing to help his issues but make him listen to me LOL.
Recently, I read where he is now a convert to my trim methods and now uses .5 positive in his wings with the c/g forward it`s good to see that Ive not been shouting this from the roof top for nothing. Hum,,, May be now he will stop calling me the White Ethiopian !

A rearward Cg always effects knife edge first , causing a need for throttle to rudder trim,Have you ever seen the flat stall strip glued to the rear of a rudder to calm it down around center? ,any time the Cg is too far back the Snaps, spins and knife edge suffers, the better the knife edge flight trim the better the snaps and spins will be.
If you have to spin your airplane with elevator and rudder only , your tail heavy and will need a left rudder mix.
I have heard of guys actually adjusting the elevator halves different to help with the left rudder knife tuck ( it can never get rid of it) now please tell me Why we go through extreme pains to build a perfectly straight airplane and them adjust it crooked? makes no sense, this will cause you to carry a couple clicks of aileron trim ,and if you didn`t have a knive edge rudder to Aileron mix, you need one now.lso, We try to use fancy excuses for this like, Gyro effect, spiral slip stream ect but it`s only from a rearward c/g.
those words sound Nice and you sound important saying them but it`s not te cause of the issues, we must let common sense prevail. or we cant fix real problems just gum um to death in the pits with fancy vocabulary.

Then I hear not all airplanes snap and spin the same ,,it`s a lame excuse for a poor trimmed airplane Sorry,if it looks ugly it aint a snap or Spin the control throws , C/G were never accuratly adjusted to do the maneuver correctly.
If you have to enter your spins with rudder, you don`t have enough positive inc. in your wings and your c/g is too far back to boot! this makes it look ugly because your wings are not stalled. Up elevator should be the only input used to enter a spin if you enter spins with rudder, or by flipping a high to low rate elevator switch,it`s fake! anything else other than elevator used to enter a stalled spin entry is a forgery ,,,fix the knife mix ,,spin entry is easy esspecially in the wind.

I finished a comprehensive writing on this subject in the next Model Aviation with more in dept methods
if you follow this method you will be surprised at how much better you can get a pattern plane to fly.

I hope I didn`t bore everyone you may have guessed trimming is my favorite subject ,not spelling LOL

Bryan

White Ethiopian?? Golly gee willikers

MattK

Hey Bryan,

Don't worry about being boring and long winded with trimming details. Those that get bored either disagree with you or have perfectly trimmed planes. The rest of us eat it up because we are starved for more (and have planes that need help!). Looking forward to the MA article. In tghe meantime keep it coming our way!

Thanks,
Tom

Hi Bryan,
How do you apply this to a 'bipe'.
Do you set both wings the same and +ve.
Regards.

Brian

PS; I set my Zeque +ve .5 mid last year and moved the pack (5350) forward 3 ins and got a great result.

Hey Bryan

I just ordered the Valiant but was not able to get any info on the Strake or the Building Instructions. Any chance Reno has both of these items that you could get included with my order that is supposed to go out tomorrow!
Also can you tell me what Hyde mount, header, & pipe, prop, & fuel you recomend with YS 170 DZ CDI.
Thanks for any help.

Dick

Wow we set the hook! I hope we see you on the trail this year,
Andreas has not uploaded the build instructions Yet I`m not sure when he will get it up I know he`s wrapping it up now. But there is a very good Build thread on here some where done by Stuart Chale,A Great Craftsman ,it`s an elec. Build But I think there is enough info for you to glean, you won`t have a problem getting it done.
If you have any Questions , E-mail me.

Use the Hyde LR85 mount and the apc 19-11 prop the Pipe to use is a Hatari 821 and the header is a 822 I think LOL (the mid rise Header you can see them on the Central Hobbies website) I use the Central Brand NMP, "fixed gear Aluminum axles" and the Dubro 2.5 Diamond Tred Light wheels ,,and grind the treads off in a drill, they are 8 grams each and will last all season.
Use the MK BB 2.5 mm adjusters and clevises on Central Carbon rods and titanium ends.
I have this all layed out in the Manual I hope it is available soon.

The Strake is being made now I`m not sure he has them ready yet but it should be done soon.
I`ll keep you informed,,
I would like you to fly without it before you put it on so you can feel the difference it makes. the airplane flys fine without. but better with it.

Hope you can make a few events this year
E-mail me if you need anything
Bryan

Thanks Tom.

Guys ,I got a few pm`s about this.
I want to clarify that I`m not saying you have to fly nose heavy, I just use the term to explain the difference it`s a relative term,
you can only move the C/G forward if you use positive in the wing.
the more positive you use the more you have to move the C/G forward. there is however a saturation point.

Here is a good Standard to remember
If you have an Airplane with thin wings Say like the Zeque you will need more positive inc because the airfoil is not very powerful, Small,ish wing erea thin wing Start with .5 Pos But you will probably need to move more.'

We are trying to lift 1G
On an airplane like the Integral a little more area, a little thicker airfoil .5 is probably good, then, put the cg to 27% or till the left rudder knife edge pass is straight.
Remember the bigger the wing/thicker the airfoil the less inc you can run.

If you have an airplane with a 1000 sq. wing and a 12% thickness you can get away with .3 pos But there will still be a small belly tuck on left rudder knife right rudder will be fine however, your airplane will fly pretty good every where But you will get slid around in the wind also your 1.5 snaps will be ugly and hard to tame.
All Airplanes snap better with a forward C/G and pos inc. I`m talking about just throw the sticks in the corner Not a fake job only the pro`s can do.

Here is another rule of thumb,,if you have to use full rudder throw to do any snaps, your cg is too far back and is probably why your 1.5 snap Pos or Neg. is so darn Ugly
You should never need more than 40% of total rudder throw to do a one rotation snap ,and you should use 70-80% of rudder throw on a 1.5 snap + or -
Snaps and spin landings are controlled with rudder ,,rotation is controlled with ailerons if you have it set up reversed ,,you will never get a consistant landing on spins and snaps ,,,
well, unless you use rudder,and elevator only for spins ,,I talked about this earlier.

You should have at least 20deg. of throw in your ailerons for snaps ,,,,,get the rotation from the wings ,and the snaps are stalled ,,and start looking good ,when you get rotation from Rudder ,thats where inconsistency sets in on rotation (becomes very speed sensitive) and exits.
This is the most missed set up in the Masters class, and the point where most points are lost. Study this and don`t be affraid to make some changes. when you start using high Aileron rates and low rudder throw ,, it will amaze you how duplicatable the exit become.

Brian ,
on the Bipe I will hold that secret close to my vest,it will set my bipe designs apart in the hobby for a long time.
I can tell you this Last year, Chip told me I will regret ever messing with a Bipe ,,He could not be farther from the truth.
I have learned more in the last year designing and trimming the Shark, and it was the most revealing info I have learned in the last 25 years of designing Pattern planes.
Doing my research before I started, and trimming after ,I found No Body knew what they were talking about. not even me. LOL and don`t even read the full scale stuff!
Really, the rules for a Bipe does not change from the mono`s the indicators are the same. learning what to do with the info the airplane feeds back is hte key to success.

But after 10 different wing configurations I can tell you no one would have ever guess the correct setting.
some settings work ok just like the mono`s, but there is a magic setting ,just like the Mono`s
My Bipe has no throttle to rudder mix no roll coupling ,,I can do the complete pattern on knife edge using low rate rudder Bipes are great!
I had a good time learning.

a little long again ,,sorry
Bryan

Hey Brian
Thanks for all the info.
One quick question for you and the forum.
Oops too much thread creep, will start a new thread.

Bryan
Trying to get everything lined out so I can get started on the aircraft as soon as it arrives.
I need to know for sure what Hatori header [822 0r 823] and which Nishioaka pipe mount [37 or 29]?
What tank mfr. and size are the tank formers set up for? I am planning on usinf the CHS variable angle horns and clevises on control surfaces with the IMP on the rudder. CHM carbon rods & ends but what length? [24 or 36]
Tettra on the pull/pull. Any issues on those?
I am using your suggestions on landing gear/wheels & Axels with the MK tail wheel assembly.
I am having trouble locating the Cool Power 30% Heli LS locally, any suggestion on that. I probably will order at least four cases or more if necessary?
Thanks again for all your help and any suggestions will be very welcome.

Dick

Bryan, please ramble on! I learn with every post. Great stuff!

Volkert

Thanks Volkert

Dick, Yes the 822 header is the one you need, use the 37mm pipe standoff.
I use the 18oz Tetra crank tank ,,dont use the 17oz it`s not the right shape for the tank mounts
cut/sand the tank mounts so you can add split fuel tubing to help with wear on the plastic ,,,see link below how I do it.
on the carbon rod /titanium ends the short one are all you need. you want the 2.5mm rod ends
use 2.5mm MK bb linkage/ 6 adjustable rod ends and 4 bb clevis ends,,if you use two on the rudder pp. you only need two for ailerons otherwise (caution some may be drilled oversize make sure you test fit and use blue locktite on the bb clevises)
The chs Variable angle clevises are fine But be carefull sometimes the factory does not put the wood blocks in the wings in the same place (where you need to put the horn) So I just glue a 3/8 dowel in the ailerons and drill that, it`s much better in the long run.

On the elevator halves I use the supplied horns in the kit
Tetra PP is fine.
use a central Hobbies nose ring,
I have included a link so you can see how I set the proto up ,,a lot of good picks to look at
It will help you with the building if the instructions are not up in a week or so.
Put the CG on the middle of the tube / that means the battery will have to be close to the front,even with the CDI unit.

On the fuel I can Call Cool Power if you need, to know who the distributor is there ,But,
you can use regular Heli fuel just a little more smoke anyway.

Bryan

Hi Bryan
Thanks for the reply.
Couple of things.
1. Where did you get the cheek cowl latch system. I like it?
2. Do you have any close up photos of the canopy hold down system?
3. Can you better show or describe the fuel plumbing [engine bay] including the exterior "line pinch" system?

Do you have any info regarding the YS engine soft mount I asked about in the "breakin" thread?

I have one case of Cool Power Heli 30% LS coming from Tower but the cost is outrageous! There has got to be some place we can get it cheaper in quanity ordeers?

In that the firewall is not installed, I am going to need a procedure to do that to get the correct incidences.

I have everything I need to get the acc. I need except the info on the YS mount. I like the looks of the mount design assuming it can be mounted in the Valiant and is not to heavey!
The engine arrived today.

Thanks again for all the help. Sorry to have to ask so many questions but not being active in pattern for 15 years and a new plane has me lacking experience in the new technology!

Dick