aviationinfo

My Feedback: (3)

Hi Mike:

I've gone all through this forum getting your answers on power setups for large scale IMAC planes, and I see that for the size I'm flying (33%) your preference is not for some of the higher tech power systems, like Powerboxes, etc. Correct me if I'm wrong, but you'd suggest perhaps 2 batteries plugged into the receiver (w/2 switches) to power everything. I see also that pretty much everyone has gone to a 6v. system.

Do you advocate using any kind of RF isolation system? I believe that one may even have voltage regulators built into it. One example is the I4C, I'm sure you've seen it. If not, do you then use voltage regulators for each battery between the battery and the receiver?

Also, if you don't have any kind of multifunction RF isolation system on board, do you then use chokes on every servo? I'm thinking that there could be issues with the electronic ignition systems and RF noise, but am new to gas engines.

Thanks for your input, I appreciate reading and learning from your posts.

Andrew

MMcConville

My Feedback: (4)

Easy answers.

1. For 33% models, I use 1 x battery plugged into the RX. I dont go to 2 x batteries into the RX till I get to 40% size models

2. I do not advocate Powerboxes. I subscribe to the KISS principle and the philosophy of "if it aint broke, dont fix it". I have never experienced a need for a powerbox or experienced a problem flying w/o one. This is true for all models including my TOC airplanes.

3. I have never used an RF isolation system. My belief is that if one is needed in a model, its a bandaid covering up a problem that needs to be fixed, i.e an EMI issue, a bad rx, a tx output problem or something else.

4. Yes, 6V system always. More servo power and more speed. I use 6V on all models unless they are non-aerobatic types like a J-3 Cub or maybe a warbird. Yes, use a voltgae regulator between the batt and rx.

5. I use chokes only on any lead coming from the nose of the model to the rx, such as a throttle servo lead, or the rx battery lead if the battery is in the nose for CG reasons.

IMO, I see many guys putting way more complexity into their models than is needed, and a lot of guys are putting as much or more gear into 33% models than is even needed in 40% models, which results in an overweight model and a much less enjoyable flying experience. Hope this helps.

budgetdude

My Feedback: (6)

What regs do you run?

MMcConville

My Feedback: (4)

I use Duralite regulators

aviationinfo

My Feedback: (3)

Thanks Mike, I appreciate your time. I can see that simpler is better, especially if I can avoid making dumb mistakes.

Another Q from a Newby Gas Guy?

Do you think PCM receivers are the way to go then, for a 33% plane?

I also found one of your posts where you said you only used a Matchbox on a multiple rudder servo setup. Does that mean you try not to use them on multiple aileron servo setups?

Thanks again,

Andrew

MMcConville

My Feedback: (4)

Yes, I do think PCM receivers are preferable.

On Matchboxes, I use them on any surface that has multiple servos driving it. AIlerons, rudder, and if the models had 2 x servos per elevator helf then I use them there too.

If the rudder servos are being pushed really hard, then I will use a seperate battery to power only the rudder servos through the Matchbox, which is probably what I was getting at in the post you read. Though, since the 8611 came out, I have gone away from doing that (this is on 40% models) and power all 3 8661 rudder servos through the rx.

aviationinfo

My Feedback: (3)

Thanks Mike! One last Q, and I won't bother you again (for awhile...!)

I have an older PCM - Z receiver that works real well; it's a 7-channel. It's a JR--- NER 627 XZ. I've been using it with my 8103, which in the long run I plan to replace with a 9103 or maybe even a 10X, (and therefore get a newer receiver) but not just yet. Do you think that receiver would be sufficient? I know it's not the latest, but it works great. However, I also don't know much about the modulation and how it may have changed since that receiver was made - probably 10 or more years ago.

Thx for your thoughts.

MMcConville

My Feedback: (4)

Well, just a couple of things. First, Z PCM is 512. So the resolution is pretty low which isnt great for flying precision.

Secondly, its getting pretty old, and old electronocs, especially the heart of the connection to the TX is something I'd be cautious about.

budgetdude

My Feedback: (6)

Mike do you run an electronic kill switch, if so whick one?

MMcConville

My Feedback: (4)

No. But I do set my failsafe to low throttle.

Bobby Folsom

Hello Mike. I have a couple of questions that stem from the conversation above. I really would like to run only 1 Duralite 4000 mah RX battery on my new AQ QB Extra 260. It has 2 aileron servos per wing, one servo for each elevator half, one rudder servo and one throttle servo - all except for throttle are 8611As, the throttle will be an 8411. I use one 945S RX. I have a 2800 mah Duralite on the DA 100 ignition with an ElectoDynamic electronic kill switch.

I believe you fly the Unlimited IMAC sequence. How many Unlimited IMAC flights (1 sequence = 2 flights) do you get from your setup? How many flights could I expect to get from batteries/setup described?


Thank you for taking the time to answer my questions.

Bobby

MMcConville

My Feedback: (4)

A few comments first. I dont recommend using a digital servo on throttle. Use a good quality analog servo. Fir some reason, we see more digital servos fail on throttle than analogs. Also its not goot to have the higher current draw of a digital when its not needed.

For the IMAC flights, you means 1 flight = 2 sequences right? Not the vice versa.

I really never push batteries, but my educated guess is that with that set-up (with an analog thrott servo) you should be able to safely get 5 to 7 flights.

Bobby Folsom

Thanks Mike. Yes, you are correct about the 1 flight = 2 sequences. And, I hear you about not pushing your batteries. I may have to perchase an analog servo for my throttle becaise digitals are all that I have.

Thanks again,

Bobby

JLB

My Feedback: (2)

Regarding your use of chokes. Could you please name a source for chokes. Are these something built
in to extensions or an external device of some sort ? Always something new to learn. Thanks.

MMcConville

My Feedback: (4)

JR

Use these:

http://www.horizonhobby.com/Products...ProdID=JRPA028

Wrap the lead around them 3 times.

Solstice

My Feedback: (1)

Hi Mike,

Good information in this post! This all brings up another question I've had for some time. What capacity battery is appropriate for 40%, 35%, 33%, 30%. Perhaps a better way of looking at it is the number and type of servos being used. For example I have 9 servos on the 33% 3d/IMAC model; 7 digitals and two analog servos. What's the minimum battery capacity to use? Does it matter if LiIon or NiMh? I appreciate your thoughts.

Jay

MMcConville

My Feedback: (4)

mAH are mAH. They type of battery doesnt matter. The advantage of nimH over Nicad, and LIIon over NiMH is lower weight for a given capacity.

As for what is correct, I dont have any hard and fast rule. I believe its more than the number of servos, but also how hard they worl. My 40% Carden 260 has 10 servos in it, but I use 2 x 4000mH batts. They should be working a lot harder than 9 or 10 in a 33% model.

Normally ina 33% model I use 1 x 4000mA pack (if using Liion), a 2700mA NimH or an 1800mAH Nicad. Weight is the primary objective here (avoiding it) so if using smaller packs, I charge more frequently.

Solstice

My Feedback: (1)

Thanks Mike! Makes good sense. I agree weight is the issue. My reasoning behind asking about the various battery types was to determine if one had an advantage other than simply mah and weight. Specifically whether one type is better able to supply the average and surge amps. Simply put, my primary concern is using some the currently available double A size 2500mAH NiMH packs. My thinking is that they may not be able to provide the current when a 3d load is placed on them. What is your thought in general about using them? Should I just bite the bullet and jump on the LiIon bandwagon? Thank you for the quick response.

brn2fly

My Feedback: (190)

Mike,
I was wondering about matchboxes vs. Y harness. I have an Aerotech 35% Edge 540T with 3W106 TOC, dual Futaba 149 DP PCM receivers. One receiver has a coreless servo (Fut. 9201) for the throttle, 2 8411s on a Y harness for the left aileron, and a one 8611a on the elevator half. The servos on the Y harness pull about .01 amps ea (.02 total) at neutral and .4 amps at (.8 total) full deflection. Is this OK? The other receiver has the same elevator and aileron set, however it has 2 8611a on a Y harness for the rudder. The rudder pulls about 1 amp total at full deflection and .01 totals at neutral. I used the H9 load meter. It did take a while to work the linkages so the servos did not bind. I have matchboxes to use. I used two receivers because I was concerned about putting 8 hi-torque servos and one coreless servo on none servo because I did not want to over load the bus in the receiver. I am using Fromeco 7.4/2400 mah on each receiver as well as the ignition. I set this plane up mainly for 3D flying; however I might fly some IMAC events with it. Should I change my set up?

Thanks Andy

MMcConville

My Feedback: (4)

A few answers. First, there should be no problem using those serevos through 1 rx. I use more than that through 1 in my 40% models. I cant speak for the Futaba rx, but with JR there is no problem.


If your rudder set-up is pulling 1 amp at max deflection, there is a pretty good fight between the servos happening. The current draw should be the same at any position (on the ground) if the servos arent binding. Its very difficult to get two digital servos working well on a surface w/o a matchbox. As a rule, I recommend a matchbox on any surface driven by more than one digital servo.

In short, yes, I'd recommend changing the set-up.

brn2fly

My Feedback: (190)

Thanks Mike for your help.

BR289

My Feedback: (106)

As usual, I have learned something from this thread. Thanks Mike for the informative answers...
Blair

aviationinfo

My Feedback: (3)

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