aviator2906

I am in the process of building a Patriot XL and I am considering using smaller servos in the wing and possibly elsewhere. I am thinking maybe JR331s for flaps and ailerons. They have over 40 oz. of torque and are less then half the weight of a standard (.63oz. vs. 1.6oz.). That would skim off about four oz. They also could be mounted sideways and enclosed in the wing to reduce drag. I would also like to use them in the tail, but the way it sounds everyone is having problems with it being nose heavy with standard servos. What about custom building a battery that could fit as far back in the tail as possible? I really hate adding lead to an airplane.

Please give me your opinions and suggestions, everyone.

js3

My Feedback: (3)

If I were building a Pat XL, I'd probably do exactly as you are proposing. All except the JR 331 servos. I've heard some bad things about the 331s and have stayed away from them. The JR 341s however are rock solid.

You probably realize that most "mini" servos nowadays have more torque and perform better than standard gear 25 years ago. As long as you pay attention to correct control horn geometry these servos will be fine. Side mounted to reduce drag--yes you should do it.

As for the custom battery pack, yes to that too. You can make it just about any shape you'd like.

Good ideas!

Flyboy Dave

My Feedback: (21)

I'd be using servos in the 75 inch rating on the XL.

FBD.

bob27s

My Feedback: (19)

Good posts...

Ive considered this too. There is no reason to run 75-100 oz servos on these control surfaces. Expecially the ailerons and flaps. The control surfaces are not much different than what was found on my older 100 mph pattern ships 10-20 years ago. I flew a few of those with basic S-28 and S-130 servos when needed...worked fine. For the PatXL, servos pushing 40-60 would be fine in these locations.

HS-225, JR 341, experts, (the 'midi' size servos in this range - digital or analog) many of us use for pylon planes would work great in these applications, and probably on all of the control surfaces, and easily shed about 6-7 oz off of the plane. Throttle and retract valve servo can be HS-81 or other mini servo. Light weigh NiMH or Lipo battery would save another ounce or so.

Bob

Flyboy Dave

My Feedback: (21)

I wouldn't recommend using 40 oz mini servos in an extra large (XL) Patriot
prop jet, not even in a nightmare....

....sorry. I might use one on the throttle.

FBD.

bob27s

My Feedback: (19)

To each his own - thats the good thing about this hobby.

For pattern and helicopters I used the S130 and S131 servos for a number of years. They worked then, and my feeling is similar good quality products would work now for similar applications. These were in the 50oz catagory. Servos with 60-120oz in a standard servo package are a relatively new inovation.

The patriot and patriot XL have relatively small control surfaces - normal linkages (no ungodly long control arms or horns) - minimal control throws. Good advantage is taken of the geometry. No huge flutter/load/travel demands like with some of the 3D birds. A good quality sport servo is all that is required. Id tend to go for a ball bearing type.

Using something like a HS-425 ball bearing standard servo for flight controls would be adequate. Those are full size servos, robust gear train. Like most standard sport servos, these are in the 45-50oz bracket.

Mini/Micro servos, no. I definately agree there.

But the midi servos are great for jobs like this.

The HS-225 at 4.8v puts out over 55 oz, and the HS-5245 digital version (same size, 1.1 oz) is over 60 oz. Good gear trains, good cases, 4 screw mounting, solid package. The JR 3121,901,9021, Futaba S3002, and others in this size are all good. Ive used them on aerobatics, racing, DF jets - always reliable.