Need Help! Jets Servo
 

I have two futaba S9151 at 132 oz on a Kangaroo style jet, and for the first time today I noticed that they where not strong has I thought they were. Could anybody suggest a servo, thats standard size, full ball bearing, digital, and if possible metal gears that are very reliable? Thank You for your help

RE: Need Help! Jets Servo
 

JR 8611, I believe 260 or 280 oz at 6V.

RE: Need Help! Jets Servo
 

8611 is a great servo, but they are no longer available, some hobby shops might have them in stock. the replacements are 8611A. 280 oz at 6.0 volt. i just put the new 8611a's in my facet on the elevator

mark

RE: Need Help! Jets Servo
 

Do the 8611a have the same problem as the 8411 had ( slop, in the servo ). I need reliable servo for my jet?

RE: Need Help! Jets Servo
 

I am actually using Futaba S3050´s with 90 oz/in at 6V in a P-80 powered Kangaroo.... they work
and feel great.

If you feel that your 130 oz/in servo is not quite strong enough, there is something wrong with it
or with the installation setup... (read it as the servo arm length versus the elevon arm)


Enrique

RE: Need Help! Jets Servo
 

i have to agree with the above statement, 135 oz servos should be more then enough, the guy i fly with all the time had 130 oz servos on all controls and fly's great

so check your set up. maybe your rods , from servo arms to control arms are flexing under full power, i switched over to carbon fiber rods and they work great

mark

RE: Need Help! Jets Servo
 

The setup of the plane is perfect, I'm Futada aluminum horn, central hobbies carbon fiber rod ( 4-40 ), rocket city hardware. Every time is free, no biding up, the major trouble is the speed of the jet and the force on the aileron.

RE: Need Help! Jets Servo
 

ok, set up might be ok, how many servos in each wing? are you useing 1 servo per wing, or 2?


mark

RE: Need Help! Jets Servo
 

I'm using one servo per wing. Also I'm using Duralite Batteries 4000 mah pack with a regulator at 5.1 volts and at the time they were at 100% full. With 22 gauge extension for Wild Air.

RE: Need Help! Jets Servo
 

Kelly,

I would agree with these guys on both counts...8611A is a great servo (no, they dont have the slop like the 8411) but you should have adequate amount of torque here...
are you running 100%+ on ATV or have you dialed the servo down for correct throw? Used single 8411 on mine w/p-120...never felt soft.
Todd

RE: Need Help! Jets Servo
 

Well over 200 mph? mine was clocked at this speed and the servos are good enough to the task. I also dont use aluminum horns, just du-bro giant horns and steel 4-40 rods without CF... still happy and alive here! ;)

as a aditional information, I didn't use a voltage regulator.... just a 5 cell batt. If your regulator turns the voltage down to 5.1 Volts, you will have a substantial less torque in those servos compared to a raw 6 Volts... perhaps this is part of your problem.



Best regards, Enrique

RE: Need Help! Jets Servo
 

The S9151 only work at 4.8 volts, and my jet was clocked in a 367km ( 228 mph ), this is the first time we hit this speed, before we where running about 340/350 km.

RE: Need Help! Jets Servo
 

Yes, my error. this servo is a F3A rudder servo that can only work at 4.8 Volts (just read it at tower hobbies) but with anyways plenty of torque for your speed range. But, it you feel better oversizing the servo of your plane, do it . there are no couter-indications for doing this, unless you didn't oversize in the same proportion your batteries capacity. (with the consequent disadvantage of cost
and weight...)

Best regards, Enrique

RE: Need Help! Jets Servo
 

When the plane was in a dive it was not responding as usual to the stick and was get very low, to me this indicates the servo where not doing there job properly. This is the reason I would like a servo with a higher torque spec. And for the batteries a 1500 mah pack NICAD is almost equal weight to a 4000 mah duralites pack, and I don't have to re-charge so often, which means more flight time.

RE: Need Help! Jets Servo
 

we might be overlooking something. even though the servo might be enough power/torque. and even if the servo is mounted perfect. you might have some flex arond where the servo is mounted.

the new skymaster hawk i just built. they had us reinforce the area where the servo mounted , reinforced it with carbon fiber, this was to keep the wing area where the servo mounted from flexing under a load.

just a thought

mark

RE: Need Help! Jets Servo
 

Sluggish elevator response in a dive is quite unpleasant! do you have pictures of your plane to show us? in particular, close-ups of the elevons and wings?


Best regards, Enrique

RE: Need Help! Jets Servo
 

The 8611A is a better designed servo than the 8611...Due to the high output of this servo the 8611 was blowing the upper case apart under severe loads. The 8611A has a re-designed case with six screws holding the case togther instead of four. You can't go wrong with this new servo!!!!!

Kevin

RE: Need Help! Jets Servo
 

The elevons and the wings are the same size as a kangaroo, the body is longer and a little wider. I don't have a good picture of the elevons or wing.

RE: Need Help! Jets Servo
 

Quite a mistery, a pic of the plane would greatly help...

BR, Enrique

RE: Need Help! Jets Servo
 

8611 servos are great. They do however have the six screws to hold the case, 4 lower and 2 upper. The new 8611a's have the same case but a new gear train and POT. We do have them in stock if you can't find them any where else. PM me and I can give you the store #. Thanks, Dave.

RE: Need Help! Jets Servo
 

I'm surprise you don't know what a Kangaroo looks like, so here a picture of my plane.

RE: Need Help! Jets Servo
 

The JR 8611A also has a different motor.

RE: Need Help! Jets Servo
 

Kelly,

I think they want a picture of your linkage. To see how far away from the servo and surface the arm is attached. To me, it sounds like you are at a mechanical disadvantage.

Mark M.

RE: Need Help! Jets Servo
 

Kelly,
You still have failed to indicate your servo servo geometry.... are you running 100%+ on ATV or have you dialed the servo down for correct throw? This could have a huge impact on the amount of torque being delivered by the servo...
Todd

RE: Need Help! Jets Servo
 

actually, the servo arm set up is fine, 99.99% of are running 2 servos on each wing, giving us 200 oz. and up -per wing side. kelly, you are only using 1 servo at or about 135 oz. you need to upgrade the servo, 8611A or run 2 servos per wing. that should solve the problem.

mark