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Need advice about servos

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Old 02-27-2019, 09:02 AM
  #26  
Real2You
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Thanks Jester...all good information!
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Old 03-04-2019, 10:44 AM
  #27  
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Also guys being that we are on the topic of these two planes....is using an AR620 receiver and two 6V..2000MAH..5C...NiMh batteries in parallel the way to go? Seems two batteries in parallel adds weight....are their other battery options that you guys use?
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Old 03-04-2019, 12:05 PM
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I usually do not run dual batteries until 50cc size. That being said, there is no reason not to. I would however suggest LiFe batteries as you will save some weight and they will deliver more current then the Nickel Metals. They will also not self discharge or develop a memory. I would run a single 3000 MAH or Dual 1800 MAH. What I worry about the most are switches. Get a good quality HD switch or better yet I have started using these. They also have a dual input/output style. I have one in my 70cc Reed Falcon.


https://alofthobbies.com/zepsus-dual...itch-7amp.html
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Old 03-05-2019, 06:40 AM
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I never went down the two battery route [ with one exception ].

IMHO You are just creating more things to go wrong.

The most I used was a 5 cell NiMH pack with 1800 mah capacity and happily flew turbines and 20 ft span gliders on them.

Buy good cells and switches and check at the beginning of every season. I also flew a lot of small stuff on 300 mah NiMH packs and those got replaced every 3 years.

The only time I used two batteries was on models with mechanical retracts and a retract servo. The retract servo was on a separate battery so if it stalled then it did not drag down the main battery. This needs a bit of signal wire switching but it is well documented.
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Old 03-05-2019, 07:21 AM
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Thanks guys...I'm gonna go with one battery and a good quality switch. Thanks.
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Old 03-26-2019, 01:33 PM
  #31  
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Hi True2You! That Sig Cub will be a great flying aircraft. As far as the engine choice, if you want a rocket ship that will do loop after loop with the application of full throttle and full up elevator go with the 70 4-stroke. If you want to fly in a scale like manner go with the 40 to 45 4 stroke as recommended by Sig. When this kit was designed some 40+ years ago the model airplane engines didn't have as much power as they do today, but they still flew okay on the recommended engines. A full scale Cub has a top speed of about 85 and a cruise speed of 70-75. To do a loop one had to put it into a dive to gain enough airspeed to make it over the top of the loop.
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Old 03-27-2019, 09:16 AM
  #32  
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Thanks....I ended up getting a .62 4-stroke for the Cub and a .46 2-stroke for the Kadet. All the information I received has been very helpful!
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Old 03-27-2019, 02:17 PM
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Just a word of caution. With the 46, that Kadet, since you didn't tell us which one, could be like a rocket when compared to the Cub.
A Kadet MKII will be much faster since it's a 56" span plane, if build with the dihedral shown in the plan and instruction book
A Kadet Senior or Seniorita will be about half way in between the MKII and Cub since they have an overall lighter wing loading but are larger(meaning more drag) than the Mk II
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Old 03-27-2019, 02:35 PM
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Just a word of caution. Depending on which Kadet you are building, that 46 could make it like a rocket when compared to your Cub.
The Kadet MKII only has a 56" span but is a heavier build, with 18 oz/ft wing loading(33% higher than the other two Kadets) so it will and probably must fly faster than the larger Cub or Kadets
The Kadet Seniorita has a 63" span but is only rated for a 25 so it will probably be overpowered and nose heavy
The Kadet Senior has a 78" span so it should be similar in speed to the Cub

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Old 03-27-2019, 02:49 PM
  #35  
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The Sig Cub is lightly built compared to the Goldberg or GP Cubs, and absolutely they fly well on a 26 FS. The Saito 62 is a wonderful engine, but way too much power for the Sig Cub. And wait till you put it up against the plan and it doesn't fit. An experienced builder can modify it, but is that really what you want to fuss with?

For your Kadet a 46 is a lot of power, unless it is an OS 46 LA, which would be fine. If it's a ball bearing type, it will be WAY more power than you need. As people will say, 'you can always throttle back'. But you might be surprised at how little movement of the throttle stick will give you more power than you want. I've been an instructor for many years and I know what happens when a beginner suddenly gets more power than he can handle. Of course, the instructor with a buddy box can take over, but it's not an effective way to learn. Don't you want to be able to enjoy your airplanes?
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Old 03-27-2019, 09:45 PM
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Originally Posted by buzzard bait View Post
The Sig Cub is lightly built compared to the Goldberg or GP Cubs, and absolutely they fly well on a 26 FS. The Saito 62 is a wonderful engine, but way too much power for the Sig Cub. And wait till you put it up against the plan and it doesn't fit. An experienced builder can modify it, but is that really what you want to fuss with?

For your Kadet a 46 is a lot of power, unless it is an OS 46 LA, which would be fine. If it's a ball bearing type, it will be WAY more power than you need. As people will say, 'you can always throttle back'. But you might be surprised at how little movement of the throttle stick will give you more power than you want. I've been an instructor for many years and I know what happens when a beginner suddenly gets more power than he can handle. Of course, the instructor with a buddy box can take over, but it's not an effective way to learn. Don't you want to be able to enjoy your airplanes?
So, are you saying my "word of caution" was well founded?
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Old 03-28-2019, 04:11 AM
  #37  
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Yes, Hydro, I completely agree, and I think the power for the Cub is too much too.

Back when the original Kadet came out a typical engine would have been an Enya 35 or a K&B 40. Those were in the 11 to 12 oz range, maybe less. If someone sticks on a 17 oz ball bearing 46 that makes twice the power, the combination of weight and power is not ideal for a trainer. Yes, you can do it with a buddy box, but why? I'm just reinforcing what you wrote. My Kadet Mk.II was an excellent trainer with an OS 40 FP, which was about the same power and weight as the older engines.

I had an OS 46 LA on a Kadet LT-40 and that was a good trainer engine, but it's only 12 oz and the power is very adequate without being over the top, so I think the 46 LA is the exception. I think you're absolutely right to caution him on using a 46.

The Sig Cub, even if built on the heavy side, will fly nicely with a 40 four stroke. Built reasonably light, a 26 is fine. The original was designed for a .15 to .19. Sig has beefed it up since then, added ailerons, but it's still a light airplane compared to most RC planes these days. A more powerful engine will add weight, be harder to install, squirrely on take off, and it might be hard to get it to idle slow enough to land. People do it, but I don't know why, and I certainly wouldn't suggest that much power on a Cub for a beginner.
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Old 03-28-2019, 08:41 AM
  #38  
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Now this is why these forums are good! I am learning a lot by just asking a few questions. The Kadet is a Mk-II. I definitely want to put an engine on it that is good for a beginner.....although I don't plan to fly it until I at least go through a few foam trainer type planes. Reading all these posts about oz. this and ball bearing that....gets me to reading and learning. I appreciate all the interaction. Thanks guys!
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Old 03-28-2019, 08:07 PM
  #39  
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It doesn't always work out quite this well, but we try.
Now, let me throw something else at you. Your foam planes won't really help you that much if they have the "auto-save" system in their electronics. They also don't respond the same way as a plane with a nitro motor will. Too far off the throttle of an electric and the motor stops. Advance the throttle and you have instant power. Too far off the throttle of a nitro motor and the engine quits. At that point, you better be good at gliding since that's all you can do since there's no way to restart the nitro motor in the air. A foam plane also doesn't have the wing loading of a balsa plane. I also found a review on the T-28 Trojan, if it's the Horizon BNF version:
A couple things I would look out for. First is the landing gear is not fitted well. It tears off with anything that is remotely rough when it comes to landing. I've opted to simply belly land and thing have been much less stressful. Also as in other reviews the elevator is awfully touchy. If you pull back too far on your transmitter, the plane jerks in the direction you are trying to go. It can make landing jerky-jerky looking. But with practice and the mental block to not pull on the stick helps remedy it. I'm running 70% expos as well and still have issues keeping it from jumping all over the place. I'm going to try using low rate for the elevator as well next flight to see if that helps. It's strange as the ailerons are perfect and roll the plane at almost a scale rate. I recommend this as a second plane or warbirds trainer. Again it flies very stable and is a blast to put in the air!
This doesn't really sound like a good first plane to me but, then again, that's just my opinion
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Old 03-29-2019, 05:51 AM
  #40  
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Originally Posted by Hydro Junkie View Post
.....Too far off the throttle of a nitro motor and the engine quits.....
I beg to differ with you. Not if the engine is set up properly. When you bring the throttle stick all the way back the engine should just continue idling until you advance the throttle. I have two Futaba radios with a throttle cut feature to kill the engine when you want to. Older radios I would just move the trim lever all the way down to stop the engine and then move it back up to idle again.
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Old 03-29-2019, 06:48 AM
  #41  
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Originally Posted by Real2You View Post
Hello all,
First time on the airplane side of these forums. I'm building a Sig J-3 Cub 71" wingspan(first build of an airplane of this size).
The build is going good and as I get closer to completion I am wondering what are good servos to use. As a beginner I will just be doing basic flying.
I have been trying to read information about different servos but I thought I would get some real life advice. I think I will need 5 servos...any advice?
Thanks.
What brand of radio do you own? I like to stick to the OEM manufacturers servos.
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Old 03-29-2019, 08:17 AM
  #42  
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I have the 1st generation DX7...but I have been flying the UMX Timber on days where there is little wind and it has helped but I do know those planes are pretty easy to fly and are a lot different than a nitro plane and other electrics. I was hoping to fly the T-28 next. One way or another I'll learn...
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Old 03-29-2019, 10:49 AM
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Originally Posted by pmcafee View Post
I beg to differ with you. Not if the engine is set up properly. When you bring the throttle stick all the way back the engine should just continue idling until you advance the throttle. I have two Futaba radios with a throttle cut feature to kill the engine when you want to. Older radios I would just move the trim lever all the way down to stop the engine and then move it back up to idle again.
Having a radio(without a kill switch) set up that way was common over the years but, with a beginner, it would be very easy to shut down the engine and not move the trim back up, been there seen that. The instructor, who was dealing with multiple students on this day, didn't notice that the trim was still down on one of the radios when it was time to fly. The student gave the plane some throttle, started it and up they went. When it came time to land, the plane's engine quit after throttling back. The student then was talked through a deadstick landing, after which, the trim switch issue was found. It was a "wake up" call for both the instructor and student as both forgot to check the radio settings before flying. With a multiplane computer radio, it's even more important to check the settings or, as many pilots have found, you could be flying one plane with a radio configured for another. Getting back to my point, plain and simple, an electric foamy doesn't fly the same as a nitro powered balsa plane.

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Old 03-29-2019, 01:22 PM
  #44  
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Originally Posted by Hydro Junkie View Post
Having a radio(without a kill switch)......................................nitro powered balsa plane.
Yup, I know what you mean. Have probably done that myself sometime in the past. I use a written checklist I run through before each flight to prevent such things, like forgetting to plug in the aileron servos. I've done that. LOL! The checklist remembers a lot better than I do. Of course, now that I'm 66 and do something stupid, I can blame it on just having had a senior moment.
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Old 04-18-2019, 04:07 AM
  #45  
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Old 04-20-2019, 01:49 PM
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Hi!
I agree with "Buzzard Bait"! Too big engine in a trainer is no good!
Been and instructor for 40 years and seen many newcomers with too big engines in their trainers getting in trouble just because they have too powerful engine up front.
The SIG cub would fly just fine on a OS .LA .40 swinging a 12x4 prop. A .70 four stroke is just to powerful!, At least if you fly at sea level.
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Old 04-21-2019, 06:58 PM
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Thanks jaka...one thing I have learned from this forum is there are a lot of ways to skin a cat!! I imagine a person's skill level dictates how much power they want on their plane. I have definitely learned a lot from all the input and it's appreciated.
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Old Yesterday, 07:53 AM
  #48  
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I guess I am going to play devils advocate here a little. One thing that I have noticed at several flying fields are guys who have a lack of throttle control. Sadly it's not just throttle but rudder as well. When I was taught to fly, the first thing my instructor ( dad ) did was to take me to the schoolyard behind our house and have me drive the airplane around on the ground for a couple hours. The first things I learned was throttle and rudder control. It also helped me deal with the control reversal when the airplane was coming at me. IMO it's better to learn to contol the power available as opposed to limiting it. Flying an airplane in a situation where you are behind the power curve is quite difficult as compared to learning to control the power IMO.
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