piotrekpepe

Christopher Paysant Le-Roux and Benoit Paysant Le-Roux used in France servo FUTABA S9254 for elevator!! Why they used heli servo 47.2 oz-in. (3,4kg) torque? In my opinion it is too low power for elevator.
Please see my photo of his Oxalys from WC F3A 2005 in France.

stek79

I've just checked... this is the FASTEST futaba servo! 0.06 s / 60 deg @ 4.8 V!!!

It seems to be very low torque, 2.8 Kg-cm ... Interesting!

Regarding power, we have to consider also elevator control horn height: if it is very large the actual torque could be 2 times or even more.

Perhaps do you have elevator pictures?

piotrekpepe

I don't have better photos. In this photo we can see, that's horn is not very long. Normal horn, which is used by many F3A flyers. Some competitors use very bigger torque servo with longer horn...

bla bla

Our elevators move so little during flying why would one need mega kgs thrust? Don't bother answering that, instead look at it this way.
The sales of S9254 are about to seriously take off... much to the amazement of Futaba!

bwick

Man he needs to learn how to build. Look how messy that thing is!

jamesjoneill

guess this goes to show that as long as the model is straight and structurally sound, how it looks inside doesn't matter at all!

jaycey

Interestingly maybe is that it looks like a MK Dual Elevator bellcrank and MK recommend minimum of (I think!) 7kilo torque with that pruduct.

jamesjoneill

Hi Jason,

yes they do, although I never worked out why. All it does is transfer the force from the internal pushrod to the two outer pushrods - the same as a Y-pushrod would, and yet it does it with more precision and less slop than most if not all other methods. Thus it should not effect the required overall servo power, that should be governed by the surface size, flying speed etc only.

I work on the principle that I don't require the ultimate in speed (unlike a heli tailrotor for instance), so I might as well go for the maximum torque I can. The theory being that this should allow the servo to hold the surface position no matter what. I have settled on the JR DS8401 as being one of the best F3A servos about at the moment (11kg, 0.18s).

However as with all of these things, personal choice comes into it and if BPLR is happy with the 9254 then fair play. It doesn't seem to be holding him back!!

One thing that occurs to my cynical mind - I wonder if they changed the servo name plate over to psyche out the opposition???

James

cameron

Didn't Chad Northeast mention a while back that CPLR used a seemingly tiny elevator servo at the 99 worlds?
Very similar torque numbers if my memory serves me correctly. Chad?

Cam

can773

My Feedback: (1)

Ya he ran a 9102 aileron servo (non-digital) in '99, they are around 50 inoz or so.

2001 he was running a 9252, which is about 90 inoz...

Cant remember what he used in 2003, but there is probably a picture somewhere.

The rotation rate in both CPLR and BPLR snaps in France was incredible, I suspect that is the reason for the ultra fast servo.

f3a05

But where did the initial line break go?

MTK

This type of control horn has too many force transfer points and is more susciptible to long term problems. The biggest advantage it offers is manipulation of the moment arms such that a small servo will serve the purpose just fine. What's the big deal?? CPLR recognized this and uses it to his advantage. So can you.

regards,
MattK

apereira

We are getting used to the fact that there new servos with so much brute power that it might be affecting the way we chose our equipment, I used to fly a Finesse with a single 50oz servo with no problems (YS120AC), but if you have so much power and use a lot of deflection you are (in F3A) loosing a great deal of servo resolution because of the dual rate , it might be that the ball bearing dual bellckrank offers no resistance and the elevators are probably balanced, so using the required elevator throw and not 3D throw actually gives you better response and precision thought resolution, remember that servo was intended for a tail rotor and is the only one that can react fast enough to the gyro commands and with precision, and that , does not mean in anyway he might be using a gyro at all, he is just analyzing what he really needs of is better for the function, that is very clever.

Regards to all

smok

Hi guys, I am not familiar with F3A rules, so I am just curious if gyros are allowed at all to be used in competitions ?

cheers,

Smok

Sprink

Gyros are not allowed.

Certainly BPLR apparently flys with very little throw on his control surfaces, so little power is needed.

I too would tend towards the high speed servo over the high torque to improve response, except the rudder where you do need the power, and the speed is less of an issue.

If you compare the size and depth of control surfaces, the elevator comes out at the smallest, so intuitively needs less torque than either the ailerons or rudder.

bla bla

It may well be the fastest servo... 0.06s at 60 deg but how long does it take to bang the sticks into the corners. Shurely the servo, regardless of what speed, can only be as fast as the human fingers on the sticks, in putting and out putting the command. Obviously fast fingers run the the Frenchmans family. Snap button anyone?

Adamg-RCU

Servos have advanced enough that we no longer need the strongest servo on the rudder. The JR 8611a has something like 320oz/in on 6v! I doubt we need any more than 175oz/in, so I'm hoping JR re-gears the 8611a to double the speed and halve the torque.

Dean Pappas

Chad,
They just weren't snaps!
You don't need power if you aren't pitching the plane far enough to break.
Of course, CPLR had lots of companny in the finals ... like all nine other pilots.
When the stuation after lunch looked like third might be up for grabs, some of the pilots proved that they knew they weren't flying snaps, by bringing their real snaps out of retirement. It's obvious that some of these guys do not even practice a real snap, 'cause they were ugly! But, they knew that there might be points to be had, if they did a real one. So, it's not my opinion as to whether the finalists were doing real snaps, or not. We have their own connfessions, with the sticks.

Let me sum up, justy so that no one can accuse me of being vague. (vbg)
What I saw in the finals this Summer was a travesty. The sad part is that both judges and pilots accepted it.
Now Io know how lemmings can march into the sea, en masse.

best regards to All,
Dean Pappas

Tangy Tom

What a load of rubbish. You obviously haven't a clue what a snap should look like if you are claiming that all ten finalists were not doing proper snaps. Textbook examples of snaps were demonstrated by Onda and Chip.

Granted some of the snaps were borderline/illegal e.g. Benoit's during the prelims (for which I personally would of zeroed and he may well of been, never saw his score sheet), but come the finals I would say his and CPLR's were legal, just. The other 8 finalists snaps were undoubtedly snaps, no doubt about that in the slightest.

Can we not just have faith in our judges for a change?

Tom

NJRCFLYER2

My Feedback: (42)

And what does the text book say please?

jamesjoneill

I guess that the real conclusion here is that with the ever increasing power of the modern servo, especially digitals, we've lost site of just how much power we really need for an F3A plane.

That a 2.9kg servo works on the elevator is clear, whether it is theoretically enough power is irrelevent.

However just because it suits BPLR's style of flying doesn't mean it will suit everyone elses. I would suggest that it doesn't make a huge difference what servo you use (out of the current crop of digitals and high-end analogues), so just find one that works for you!

Of course, 3D is a whole different story but that's out of our remit!

James

Anthony-RCU

My Feedback: (2)

Can we not just have faith in our judges for a change?

Tom

Interesting rumor that in 2003 a number of judges zeroed some snaps and this year all those judges were not used.

Dean Pappas

Hello Tom
Clearly we disagree. That's okay ... maybe some day, we'll do it over a beer.

The judges were briefed, with a definition of what is and is not zero-able, with which I utterly disagree.
They were told that if the maneuver could not be readily identified as either an axial roll, or as a barrel, then it must be a snap.
This is a dreadful cop-out.
It is up to the pilot to demonstrate to the judge, so that he has no doubt, that the plane was driven to a pitch break.
It's somewhat like the difference between continental law and the legal principles under which both you and I live.
Is it a menauver if the pilot doesn't prove it, or is a maneuver unless the judge disproves it.

This is a discussion worht having, but in a different thread.
My problem is that the judges were not given free rein.
Did you not hear the murmuring in the crowd, during the finals?
You certainly heard the guffaws when pilots tried for a real break and blew it: their airplanes sure behave differently when actually stalled.


best regards,
Dean Pappas

can773

My Feedback: (1)

Hi Anthony

I am very certain that our judge delt some zeros in Poland ('03) and he was back in France.

I think whats more curious is why the judging criteria changes from WC to WC? In Poland zeros for snaps were being handed out left and right (I know I had at least 2 or 3 every flight!), in France few if any zeros for what I would call worse breaking snaps than was flown in Poland. Distance was more closely watched in France where in Poland 200+ meters was common. Seems there is a new focus each WC on a specific criteria.

That being said, I had no problem with the judging for the most part they got it right.

snap_roll

i believe tt ultra fast servos help in snap roll recovery, as they move back 2 neutral position faster, there fore making input to stop snap roll more effective eg. counter direction aileron