If you read my post again, you will see that I use a PCM radio. Not a 2.4

WBG

do yourself a big favor and get the A123's! any question you might have can be answered at these websites.
http://hangtimes.com/
http://www.fromeco.org/

Yes I had read that when I posted my comment, But He is talking about using the DX7 which is DSM2. In my experience this is a great radio. Most of the problems I have seen occur when using the DX7 have been in the setup on the plane, such as using a 4.8v pack, not the transmitter its self. Using a 4.8v on a giant scale 3D plane with digital servos puts you in a position where you could drop below the 3.5v cut off for DSM2. That was all I was saying.

I go with the old addage. Keep it simple stupid.

I have a 116 inch Davis D1W that I fly with a Quadra 35. I am using standard metal gear servos on the flight controls. I run a standard for the onboard kill. Throttle is a standard also. Believe it or not I get 4 flights on a 900MAH nicad battery. I use a switches with the largest wire available. I try to keep the battery and reciever switch close so I do not need extensions. I am flying it with a Turnigy 9x radio, HK module, and HK 8 channel reciever. It is 2.4 I have not had any problems at all.

Right now as I write this it is on the charger I am recycling the nicad to insure it is still up to par. The surfaces are HUGE but because it does not fly fast it is fully capable of handling the load.

The more complex you make something the easier it is for something to go wrong. I know guys will think I am nuts but with 20+ years in the hobby and flown many different styles of aircraft. A proper setup with smooth movement of controls do not require much power to operate.

Reliability is what you need. If what you have works good then go with that.

I am putting together a Corsair with a 75 inch wingspan. It will be powered by a HH26 gas engine. Radio is a Turnigy/flysky 9x with Assan Module and 9channel reciever. Servoes are MG996 on flight controls. throttle is a standard futaba. Retract is micro to operate the air valve built into the wing center section I only have one airline to hook up that way. Batteries will be 2000MAH nimh. I will test fly it in MAY or JUNE. I have to wait for it to warm up and dry up so I can paint. NO powerboxes, no fancy high dollar servoes. Just reliable equipment. I do not anticipate a single problem. Ground tests have been fine so far.

What I have learned about gas engines so far. Keep the reciever as far away from the ignition box as possible. DO not bundle wires. I run my engines just a tad on the oil rich side. So far so good and I enjoy the cheaper price of fuel.

You can make it as complex or as simple as you want. I just prefer a simple setup. It is far more reliable and easier to troubleshoot if a problem occurs on the ground.

What a load of garbage, the misinformation in this thread alone is priceless.

Short circuit hey, every Nicd pack which has lost a cell for me has ended up in the dirt.

Keep the input coming. I think we should just ditch all of the other threads and keep this one going. This post will become the only forum!

Personally I use LIFE, you can use any flavor, A123 or the LIFE flat packs like the Hyperion or the batteries Tower sell. I use them with no regulator, any 6v servo will handle the 6.6v and the batteries drop to this voltage as soon as a load is applied, perfectly safe and reliable. These batteries are easy to charge, do not have any memory effect like NiCd or Nimh and suffer extremely little self discharge, they will not burn your house down either. That is unless you abuse them, but that can be said for ANY battery.

Mr. Flip,
Always discuss applying excessive voltage with your radio manufacture before you stress your radio electronics in to a failure situation.

Here’s how to treat your NiCads:
Charge them at 1/10 their rated value for 16 hours prior to the day you go flying.
Measure their voltage at the field before each flight.
Cycle them every three months to test their capacity.
Discard them when their capacity is 20% their initial value;
Or discard them when they are three years old, whichever comes first.
Certainly discard them before you drill them in to the dirt.
Dan.

Dan, I know how to treat Nicds and Nimhs, I used to race 1/10th scale before 8th scale became popular, even a relatively new and fully tested Sanyo Nicd can put you in the dirt, which was my case. You do realise a 6v Nicd/Nimh pack will be above 6v for a period do you not, if the manufacturers do not put enough tolerance for .5v than I will not be buying their gear, and if you are really that worried about it, there are H.V. servos these days. The only servos i would not use are the 4.8v Futaba servos which are mainly used for heli rudder applications.

Got to move with the times my brother, Nicds are ok but not for the reasons you are mentioning and there are better and more reliable power systems out there these days.

p.s. Any battery can put you in the dirt though, lets not be naive about it.

http://www.youtube.com/watch?v=vUBIHtqpJDQ

http://www.youtube.com/watch?v=HtUkKWdF9LE&NR=1


Now If I may. altitude arcing happens just like it says at high altitude with full scale airplanes running unsealed magnetos. Idont think we should broach that subject in this venue.

There is a ton of mis-information being discussed in this thread. For example. The DS-821 servo.Dudeshow me some proof. I had those on my T-Craft and wrung that airplane out. Never 1 failure. That said read your airplanes manual and use theappropriate servo for thecorrect application. Onthe airplane videos I posted above, I contacted SIG and used the DS-821on the ailerons and used metal gear servos on the rudder and elevator.

Again there are a lot of choices to be made.There are manydifferent ways of doing things that achieve the same end result. Your way, my way, may or may not be better or worse than someother builder.

So to the OP. I think you will see a lotof BS is this thread. Some good some bad and some dont have a clue. You my friend are going to have to sift through it all and come out the end with the nuggets of gained knowledge. HoweverIwould quit reading this forum, go to your localfield, pick someone that flies gas airplanes and has been doing it awhile, then ask to look at their setup and take pictures.Do that again on another guys gas airplane, then again. You might even go to another field and do thesame.

Here is what you glean from this. You will see a pattern of how guysput their airplanes together and most of them will be similar with a few exceptions and it all boils down to choice, such as bettery placement, this radioor that. But what you need to pay attention to are the basics.How was the engine mounted. How didhe run his controls. etc. Once you gainsome knowledge. Come backto this forum and read through all the BS and have a good laugh at all the mis-info here.

My 2 cents.

Glenn Williams

Sorry partner, no misinformation here.

Spektrum/JR specifically warns against using them in anything larger than 120 size planes or nitro helis.

As for proof, go search any dedicated heli forum, there's a lot of information about the output shaft shearing clean off the top of the gear or the amplifiers dying. I personally had one go on a plane with two ailerons that was electric.

That is good information bud, unfortunately gone are the days of getting info in the modern forum, I am sorry but there is just so much information these days the only place to go is the flying field.

The ds-821 should never be used with a gas motor. Maybe you have had tons of success, but trust me the timer is ticking my friend. There is way to much vibration caused by a gas engine for a nylon geared servo.

Sorry but you are all wrong about the DS-821 servo.

Go to Horizon Hobby's website. Then look at the T-craft and pull the manual via PDF. you tell me what servo they say use. Then call Sig and ask them as well about what size servo can be used for the ailerons. I never said I use the DS-821 for all controls guys. Do your homework before you comment. Also last time I checked we are talking airplanes here not helicopters.

Glenn

Weezle, if your gas engines are vibrating excessively you should think about replacing them with ones that don't. I have been using 50cc gas engines (Brison 3.2) since 1995 and they do not vibrate any more than my .60 size engines did. I have helped guys using 200cc engines and I have never noticed any unusual amounts of vibration. Now, to be honest with you, the guys with the larger engines are financially well off so I would not be surprised if they were using expensive name brand engines. In other words, the engines were not from you know where. I have been using none metal geared servos for all my gas planes without a single gear failure and I fly for two hours every week. Since 1995, that's a lot of hours. I do admit that the gears do wear out and I replace the gears as needed. I also have had Futaba replace a feedback pot every now and then as they do get a worn spot around neutral over a long period of time. Dan.

I use a Li-Ons with a Smart-Fly Power Expander and Turbo Reg. Works just fine. Why would you use Ni-Mh batteries. You are just asking for trouble there. Btw I use a JR X9503 and DX7. With NO problems at all.

well said x1

Well, let me toss what I'm doing, and why, for discussion (target practice). Going into it, when compared to my earlier experiences flying nitro, my concerns are the amperage requirements of larger digital metal gear servos, especially if one of them stalls. The possibility of that stall pulling the line/buss voltage down to the point where the receiver drops off line is well known, ESPECIALLY when running 4.8 volt packs. I run a switch w/charge jack on each of those packs, adding to amperage handling capabilities of the system as well as adding a redundancy factor at a well known source for troubles (the switches). Power from the switches is run to the regular receiver batt. position, the second to a short Y in the line to the rudder. Regarding ignition power, you should have the ability you shut the engine down remotely, so I spend a bit extra and do that using an ignition battery eliminator circuit that's also capable of shutting the engine down remotely while I'm at it. They aren't that much more than just the remote shut down feature, and there's a couple different ways of doing this (different subject). I power that IBEC from the receiver bus (a Y placed anywhere it's convenient - usually throttle). Regarding radios, not here to slam any radios, but I do get tired of the "it's gatto be Futaba" hype. I believe in life after Futaba, and went Hitec Aurora. I can program it to do anything without a manual, or my glasses. I did that after 20+ years of Futaba ownership while making the switch to 2.4

So simply put, when going gas (26cc+) I go with 2 6v.batteries, supplying power through 2 switches, 20ga (min.) wire everywhere, metal gear servos, and an IBEC for ignition power. It's a very simple system, and supply's the extra power and redundancy to let me sleep at night. These planes are getting big and expensive enough to dent my flying budget, as well as my ego, when they go in. FWIW

sorry, double post

I would like to comment about receiver battery voltage on 2.4 Spektrum systems. (I cannot add info on Futaba, hitec etc.) If you use a 4 cell pack on a Spektrum receiver and you excersize all the controls at once, the receiver can go into Brownout or hold. This is the reason I recommend using a 5 cell pack. The brownout/hold is temporary unless the voltage drops down to below (dont quote me on this) 3 volts or so. If the battery state is less than that you will go into LOCK and failsafe mode.

To keep things simple, use a 5 cell nickel metal hydride, LIPO etc that has around 7.5 volts. If you want to add more weight and redundancy you can use a bigger battery or 2 batteries with a regulator. Again this is all personal preference.

The original Poster said he had a Spektrum set-up as do I. I have flown giant scale gas succesfully with my old DX6i and did not encounter any problems using the above mentioned set-up.

I was going to buy the DX8, but they were not available when I went and purchased my DX7. Just read the manual and you will be fine.

Now lets go a little deeper into the DX6i, DX7 and DX8 radio subject.

I can attest that if you do not have your main and remote receiver mounted as per the directions you will at some point encounter a hold or worse. THere are many videos on youtube that show this. Now if you really want to get fancy you can buy the main, remote and 2 more satellite receivers (look on Horizons web site) I dont think you need these unless you want triple redundancy.

If your airplane is built from composites make sure you buy the receiver made for that application. If your airplane is Balsa and monokote etc. the regular setup of the AR7000 is good to go.

Make sure you do a range check at the field with and without the engine running.

The key here is to have adequate receiver battery voltage and to ensure that your main and remote receivers are positioned properly within your fuselage.

Then when you go to the field always have some of the experienced guys take a look at your setup. It is very easy to get tunnel vision and miss something. I have been flying RC since 1984. I always have a couple of guys take a look at a new install to make sure I did not miss anything.

Now talking about vibration. Gas engines do vibrate, but you can minimize the vibrations. Balance your propellor and spinner. Always run your engine with the wings attached. Make sure the engine is timed properly. I will say this. I flew NITRO for years as well. I have flown "quality" gas engines and have not had the so called vibration issues that some seem so worried about. For example I had a Zenoah G-26ei in my T-craft and that engine was worked over by Ralph Cunningham. It turned 9000+ rpm with a APC 17x6 IMAC prop. No vibration issues.

On the airplane I posted the videos on. It is a DLE-55. I use a XOAR 22x8 prop and am seeing 7500+ rpm on the ground and unloaded in the air I am sure it is getting around 8000.

Again no vibration issues.

Here is the bottom line on all of the posts here. MAINTENANCE. Don't just fly your plane and put it away. After you get home do a wipe down and visual inspection of all your servos, connections, gear, engine mounts etc. A little TLC goes a long way. Take care of your equipment and it will take care of you.

There it is in a nutshell.

Glenn Williams

Ahicks don’t go to sleep tonight. Go to you airplane and rearrange your installation before it’s too late. You have violated some very basic rules about radio installations that should be corrected right away before something tragic happens. Here is what I understand from your post.

You have connected two batteries in parallel. This does increase your battery capacity but decreases you reliability significantly. When two batteries are connected together, the weaker battery will always be a load on the stronger battery. Should either battery fail it will pull down the good battery.

I don’t know what the IBEC is but it sound like you are using the same battery for the receiver and ignition. That is about the worst thing you can do and it should be changed immediately. It sounds like you have survived so far and you are very lucky. You should go find an electrical engineer, preferably a radio frequency engineer, and he will support what I have said.

Sorry, but that is the way it is. Here is something I put together a few months ago.

Your engine generates a spark around 100 times a second. Each one of those has the potential of containing radio frequency components that fall within the band that your radio is operating on. They radiate around the ignition system as an electromagnetic field and are conducted within all its wires going to and from its batteries and spark plug. By bringing the control wire to the switch from the receiver you violate all the advice from the radio manufacturer to isolate the radio components from the ignition system by eight to 12 inches or as much as possible. It is possible to pick up this RF through conduction and radiation. A lot of the guys ignore that by doing what is convenient or less expense and get away with it. This gives them a sense of security that is very false. This is good because I hate to see guys go in but all you need is a few seconds of sparks that are on your frequency and you will lose control. A ground check is also irrelevant because those nasty few sparks on your RF may not occur at that time.

Dan.

Worthless without pictures

I'll go you one better with the setup. Couple of years ago I lost a 50CC EDGE because the receiver went into failsafe at 400feet and locked. I had nothing. Watched it sail off in the blue sky until it went in. Cause of this I not only use two batteries and switches, but also two receivers. Each receiver controls half of the control serfices. You tie opposite ailerons to opposite elevators. So now if something goes wrong with one receiver I have a chance to get it back on the ground. This can be done with both 72 and 2.4 with no problem. I mostly fly large aircraft so for the small amount it cost for another receiver, it's worth the investment.

Good input James. A two receiver system is the most reliable of them all and not that expensive. It's so obvious, I'm surprised the guys who care about it use other types of methods. In the quest for reliability, they wind up with contraptions that are very unreliable. Dan.