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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Predator Servo Arms?
03-09-2008 05:22 PM  10 years agoPost 21
gas_hopper

rrNovice

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hi
i'm the same way , i run inexpensive throttle servos , just don't see the need for a high end servo with the throttle , put the money you save towards the cyclic servos or a faster tail servo , just my two cents , GH

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03-09-2008 06:46 PM  10 years agoPost 22
TooBizzy

rrApprentice

Georgetown, Ohio USA

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I checked all the Futaba Analog servos on their site and none of them has a case height of 1.3" like my 9452's. Looks like I picked a good cyclic servo that won't work too well on this machine. It is the only standard size servo Futaba has designed with this case height...Bummer...

At this point, it looks like the best way to fix this is add a spacer between the frame and the mount of the 9452's. I could add a spacer to both aileron servos to keep the geometry the same. Although, I don't know if moving the servo out 2-3mm will change the geometry all that much. I think I'll still go to the trouble to make them both the same so the geometry is the same.

I had read of the problems of using a metal gear servo on the throttle, but forgot. Thanks for reminding me, jschenck .. I was about to hit the "Buy It Now" button at Tower for another 9452! You just saved me $80+ !!!

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-09-2008 07:17 PM  10 years agoPost 23
jschenck

rrProfessor

La Vista, NE.

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http://grandrc.com/inc/sdetail/48252

I'm thinking about getting some of these for the servo mounts anyway but they could give you the lift off the frame you are looking for.

Funny, I would ave assumed the 9452 and 9351 have the same deck height. Here's is the clearance with my 9351 and 3010. It is close.

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03-09-2008 07:49 PM  10 years agoPost 24
TooBizzy

rrApprentice

Georgetown, Ohio USA

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That is exactly what I'm looking for. Thanks. Your photo shows in detail what I've been talking about. Great closeup....

Futaba has very few Digital servos that will run at 6v. The 9351, 9350, and the 9452 are about all the choices that is available. I happened to choose the 9452's! I am going to run a 6v setup using A123's and a Spectrum VR5203 regulator for the tail servo and gyro. I have 2 Raptors set up like this and so far they've been flawless.

Last time I was out, I flew my 30 for about 45 minutes, (2) full tanks with header tank, and put back 440ma in the pack. Charging at 4 amps it was topped off in less than 5 minutes. Keep in mind that you can charge these batteries at over 10 amps without hurting them.

Just letting you know the method to my MADDNESS!

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-09-2008 07:58 PM  10 years agoPost 25
jschenck

rrProfessor

La Vista, NE.

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What's the peak voltage hot off the charger on a 2S A123? I'm also going to run 6V but going the traditional Arizona + Relion

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03-09-2008 08:28 PM  10 years agoPost 26
TooBizzy

rrApprentice

Georgetown, Ohio USA

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You charge A123's to 7.2v which is considerably less than 2s lipoly. The cutoff for Lipoly's is 8.4v. You need to regulate the whole system when using lipoly's. Unless your running JR's new 8717's. For A123's, you only need to regulate the tail servo and gyro.

A123's drop to 6.6v very quickly after turning your system on. They will stay at 6.6v for 90% of their discharge. So you don't have to worry about huge swings in voltage. I have several planes that run off 5 cell nimh which peak charge is over that of the 2s A123's. I have never had a servo failure running 5 cell nimh, so the A123's should even be more reliable.

The thing I'm looking for is charge rate and safety. I live in Southern Ohio and the weather changes daily. So when the wind ain't blowin' and the sun is shinin', I want to charge in less than 10 minutes and head to the field.

A123's might save you some money over a completely regulated system. You might want to look into it.

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-09-2008 10:02 PM  10 years agoPost 27
jschenck

rrProfessor

La Vista, NE.

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I wouldn't really be comfortable running the system above 6.0V, even for a short while. I've thought about A123 regulated for my Raptor's just because of the ability to pound a charge into them. I don't have a charger with A123 capability. Which charger do you use?

Since the deck height of the 452's is lower can you just flip the ball link to the top of the servo arm? would that put the ball link on about the same plane as the ccpm linkage ball links? be a simple solution.

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03-09-2008 10:49 PM  10 years agoPost 28
TooBizzy

rrApprentice

Georgetown, Ohio USA

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I tried mounting the balls to the front or the arm, and it puts too much angle on the rods to the cyclic bellcrank. The balls have to go on the inside of the arms to keep the rods as straight as possible. If I moved the balls to the outside, I would be moving the alignment of the rod by about .300 inch. All I need to move out is about .080. I believe the spacers is the best way to go.

I have a Daptor for my Tritons and an Astroflight A123 charger. It is good to about 8 amps. It is perfect for my 2s packs, but is a little slower on a 7s pack. I have a Tripple output 30v 10a Mastech coming for my bigger packs. I believe with the Mastech, I won't need another charger. Plus I will have a good Power Supply since I don't currently have one.

If your interested, I've uploaded two pictures of my Raptor 50se. It is outfitted with a 2s A123 and the Spektrum VR5203. This is the same way I am setting up my Predator.

I have read so many times where switches fail and the reciever resets because of low voltage or goes into failsafe while running a 4.8v setup. With running multiple battery feeds into the reciever and doing away with a switch, I (hopefully) will have eliminated some of the problems with running a higher current-draw setup.

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-09-2008 11:31 PM  10 years agoPost 29
TooBizzy

rrApprentice

Georgetown, Ohio USA

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Here's some pics to show the alignment of the cyclic rod with the ball on the inside and on the outside....I only have the top rod connected in both pics, so disregard the bottom rod laying on the breather.

I ordered the PV0054 servo plates. The ones from Grand looks like they are steel. I ordered ones from Heliproz which look like aluminum. The ones on my Raptor 50 are aluminum. I ordered enough of them to go on the outside of the servo rail too. Overkill probably. But we all do it!

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-10-2008 03:32 AM  10 years agoPost 30
jschenck

rrProfessor

La Vista, NE.

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So no regulator with the A123's to the flight servos? Are you concerned about too much voltage? I think this would be the perfect setup with the 8717's but I didn't go that route, for now. Perhaps if I get an Astro 109 I'll do this.

Your photo's definitely shows the need to have the ball links on the back side of the servo arms and that the 9452 is a shorter deck height servo. Pretty sure the GrandRC part is the same as HP's, just a bad picture. Are you going to pull the brass eyelets out of the servo mounts when using the plates? Also I think we'll have to use longer screws. I think I just decided that my predator needs the plates worse than one of my 3 Raptor's

I ran into a problem with mounting the front tail servo bell crank. time for a new thread.

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03-10-2008 05:10 PM  10 years agoPost 31
TooBizzy

rrApprentice

Georgetown, Ohio USA

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So no regulator with the A123's to the flight servos? Are you concerned about too much voltage? I think this would be the perfect setup with the 8717's but I didn't go that route, for now. Perhaps if I get an Astro 109 I'll do this
I have read many, many, posts and documentation on this. Here's what I've learned. 4.8v servos were designed for use with a 4 cell battery, Nicad or nimh. Peak charge for both are 5.4-5.6v or there abouts. When they went to a 6.0v servo, it was designed around the peak voltage of a 5 cell pack, nimh/nicad. Peak volts for a 5 cell pack is 7.0-7.2v. A 6.0v servo was designed with these limits because they had to withstand the peak voltage of a 5 cell battery. Just so happens this is the same peak volts as a 2s A123. Plus a 123 drops voltage pretty fast to 6.6v and stays at that voltage for 90% of the discharge. I have been using 5 cell setups unregulated in my planes for years. No failures yet...(Knock on wood!) Theres plenty of info on this out there. Its not hard to find....
Are you going to pull the brass eyelets out of the servo mounts when using the plates? Also I think we'll have to use longer screws.
I think I am going to leave the brass eylets in. They are designed to keep from smashing the rubber pieces too tight. The rubber will then be able to do its job. I have longer 2mm cap screws I got from MSC along with locknuts. I don't think it could be done any better.

jb

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-10-2008 05:53 PM  10 years agoPost 32
jester4

rrKey Veteran

Brampton, Ontario

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Interesting about the A123's. So what you are saying is that you can run a 2S A123 without a regulator for all 6V capable servo's? Hmmm.....

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03-10-2008 06:09 PM  10 years agoPost 33
TooBizzy

rrApprentice

Georgetown, Ohio USA

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Yes....Try to digest what I posted on voltages of the difference between 4.8 and 6.0v servos. Doesn't it make sense? All servo manufacturer's would not put a product out there, that, the only way you could run it would be to run a regulator....Its only on our heli's that run most gyro servos at 4.8v that you need a stepdown or regulator. The rest of the servos that are rated for 6.0v can be run off 5 cells or 2s A123's...The only time you would need a full system regulaor is if you use lipoly's. They peak charge at 8.4v...Now that is too much for a 6v servo...

edited--added a bit more info...

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-10-2008 07:38 PM  10 years agoPost 34
jschenck

rrProfessor

La Vista, NE.

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yea, you're right - I've flown 5 cell for a long time on my fixed wing also. My Hitec's love that extra voltage. I've run 6V regulated on my 9252's which are rated as 4.8V only and they've been fine.

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03-10-2008 08:59 PM  10 years agoPost 35
TooBizzy

rrApprentice

Georgetown, Ohio USA

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Yea, the 9252's are only rated at 4.8v. That would have been my choice of servo had they been 6.0v. It gets a little confusing with so many different servos, voltages, and battery configs!

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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03-19-2008 02:09 AM  10 years agoPost 36
TooBizzy

rrApprentice

Georgetown, Ohio USA

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Update:
I bought the Aluminum Raptor servo plates and used them to shim out the S9452 aileron servos. I used two of them on each side between the servo and the frame. The shims are 1.5mm each, total shim is 3mm. Now I have plenty of clearance....SO far the case height is the only drawback of the 9452's. They seem to be very smooth. We'll soon see how they are in the air.

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...

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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Predator Servo Arms?
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