Hey hey...No I am the one and only Spooky. You just cannot stand it because you have two people that agree.

No I get a lot out of it. The Funtana .90 has a defect in it. Especiall when you use JR servos. I understand your anger. I would be too it the products I endorsed were faulty!!!!!!!

Look you are lucky to be here. If it wasn't for us Americans coming over there getting you out of trouble you would be talking German. So can it.

Doug,
Do you ever go to work or fly? Every time I get on here you are here whinning about what somebody said! Get a life dude....

Did I mention that the Funtana .90 has a defect in it?

Marlarkie, We do not talk like you do in the pacific NW. We talk the right way!

Well had enough for tonight. Been flying all day! Pretty tired. So you lucked out tonight. But I am sure I will be seeing your stupid posts. Gosh I wish i could hang out on the forum all day and tell everybody how screwed up they were! See you later you losers....

You too need to go back to your MTV and leave us! DUDE!

Doug,


A-MEN, BROTHER!!!! You 'splained it so simple even my three year old son understands!!! Seriously, very good post----Full of usefull information based on mathematical facts, not guestimates!!!!


As each day passes more and more sport flyers are getting into 3D aerobatics. The average sport flyer buys his Funtana, or whatever, to join in on the 3D craze. What the average sport flyer may or may not understand is that a plane set up with the wild max 3D type throws may not ideally be set up for being flown at max speed, pattern or IMAC. To get those extreme throws that may be required for 3D flight, one may have to set up the servo linkage to such extremes that the mechanical advantage of the lingkage becomes compromised. What I'm saying is that the throws that work for 3D may cause your control surface to flutter when the model is flown at a higher speed. No defect in the model....Just a set of circumstances that could explain some of the failures (flutter) of ANY plane that has extremely large control surfaces for 3D flying and less than ideal mechanical advantage linkage setups......After flying nothing but jets for the past 15 years I can't wait to join the 3D craze with my first 3D plane---A DA-50 powered Chip Hyde Double Vision.....[8D]

Again, good post!!!!


Kevin

this is a great thread.

some of the stuff I knew and some was intuitive to me. but to have so much ifo on this subject in one place and so well explained is a great help to me. as well i'm sure to others.

i believe my setups will benifit greatly.

thanks to all.

and BTW. i think the funtana flutter horse has been beaten into enough glue to hold both spook and startsivs funtanas together forever. get off it allready. you started your thread and made your points. this thread has nothing to do with your funtana except to tell you how to set up your next one. so please, excuse yourself from the discussion.

Doug, thank you for taking the time to crunch the numbers.

-Tom

Doug, that was explained perfectly. Now if only some would read it and try to learn something and stop beating a dead horse.

Great job Doug,
DTB

Mass balancing is desirable, model or not. On the contrary mass balancing will help control and or eliminate flutter.


Not quite... The 1/4" setup with a 1:1 ratio would be strongest (remember servos are rated with 1" arms, a smaller servo arm will increase the FORCE). The 2" setup at 1:1 would realize 50% less FORCE at the aileron, while 1/4" setup would offer a 400% increase in FORCE at the aileron.

The 1:1 relationship is based on equal length arms, therefore what ever is available in servo power (TORQUE/FORCE) is transfered to the surface. The arm lengths play a factor in mechanical advantage or the lack thereof. Ideally you're looking for a minimum of 1:1 with desires of 1":1.5" or more. In a nutshell, longer control arms reduce the available throw, as do shorter servo arms, while either of these factors can increase the FORCE realized by the surface. The inverse of these factors, shorter control arms/longer servo arms will increase throw while decreasing the FORCE realized at the surface.

After all that, your servos TORQUE is a constant and remains the same regardless of the arm utilized atop it. Servo arms will effect the FORCE available, but never the TORQUE. TORQUE realized of the surface is effected/calculated by the FORCE delivered to the control arm from the servo and the length of the control arm pivot point in use. Torque = FORCE x LENGTH/DISTANCE (T=FxD)...

nice bit of maths but not much common sense, I was referring to the leverage not servo torque and mechanical advantage, that has been explained very well by Doug.

with a 3D plane you require a 1-1 ratio with the servo to gain the right amount of throw, that’s a fact and something we have to live with. now you go away and in practical terms (not mathematical terms as in maths you are not mounting your horn onto balsa wood!) mount your horn at 1/4" from the hinge line and with a 1/4" servo arm on your funtana and I guarantee your wings would have fallen off within 1 circuit.

now do it with a 1.5" horn and 1.5" servo arm and it will be fine, resolution will be better and so will the slop as although as you said the torque relevant to the length of the arm has reduced, so has the forces that are required to move the surface by the same amount.


how many TOC planes do you see with short arms? and why to fiber classics / comp ARC make sure they supply both servo arms and horns (which are LONG) with their kits.

Dave

I was not suggesting either scenario was practical ( 1/4 " or 2 " ). Either results in the surface realizing an equal sum of TORQUE with a given servo at 1:1 ratio. How it is achieved is the variable. Model specific requirements dictate the minimum control arm overall length.

Either scenario has equal leverage and resolution at a 1:1 ratio. Mechanical advantage is not a factor, its non-existent until such time the control arm exceeds the 1:1 relationship. The servos TORQUE/FORCE is again not a factor at a 1:1 relationship, its all the same.

3D planes do NOT require a 1:1 relationship, this is FACT. A 1:1 ratio will net equal travel arcs of the servo and control surface. Simply put there is NO absolute in this regard. Some models and surfaces may perform better with less surface deflection than others suggesting a skewed ratio is preferred if not desired while implementing mechanical advantage. These things are model and pilot specific. It all boils down to the desired degrees of surface deflection, most servos are limited to a 60 degree travel arc in one direction, a 1:1 ratio will net 60 degrees travel. For example, 60 degrees aileron throw on my 40% Extra 3D bird is NOT required. It works best with 35-40 degrees deflection.

Michael,
My head hurts! So........ how would YOU set-up YOUR Funtana?

I'd recommend following the manufacturer's recommendations. The information published has proven to work and work well. The manual likely suggests a known deflection for each surface. I would setup my linkage to provide these " knowns " with ATV/EPA's within 10% percent of the MAX settings and determine the need for more less from there. My goal would be to obtain these " knowns " with as short a servo arm and as long a control arm as permissible.

I like precession servos be it analog or digital, my personal preference would be for the digitals.