flyierjon

HI all,

I am wondering if i it is possible to stick with the radio i have already for my 1/2 scale Pitts i am putting together. The radio im talking about is the JR XP652. Its a 6 channel programmable radio. I know im going to use 16 servos and a dual power interface to connect them all. but can i use this transmitter or do i have to buy a more computerized radio?

Thanks for any help.
Jon

Broken

I can't think of a good reason why not....

Tired Old Man

My Feedback: (1)

The 652 is a good radio with quite a few usuable mixes. If the plane doesn't need more than 6 channels it will work just fine.

flyierjon

I think i am only going to be useing 5 channels... ail, rudder, elevator, throttle, and smoke. I cant think of any thing else i would want on it!

Is there a electric start i could put on one channel? any one know any thing about this?

Tired Old Man

My Feedback: (1)

The retract or flap channel would work. That's a lot of weight you would be adding to the plane, though. Also a lot of battery capacity to drive the starter. The big gassers start pretty easily by hand.

jsm77777

My Feedback: (4)

Short answer is yes, no reason not too. If it works for you, it's just fine. Scott

rcblimppro

Is this a PCM radio? On a 1/2 scale pitts you will have some seriously long aileron extensions going to the upper wing I would strongly advise PCM.


Shawn Berkheimer

R/C Blimp Productions.com

flyierjon

2 servos per aileron... but whats the difference between ppm and pcm that would help with the long aileron extentions? My radio can switch between pcm and ppm... would i have to buy a different reciever for this?

ICE_MAN

Yeah you have to buy the PCM reciever.

Are you really putting this in a 1.2 scale pitts or is someone pulling my leg?

flyierjon

yes you read correctly.... 1/2 scale pitts! i going for as close to scale as possible... cockpit and all!

Tired Old Man

My Feedback: (1)

Ah-ha, a scale flyer. That perfectly explains the desire for an onboard starter.

The use of PCM will better eject RFI than PPM. From a personal standpoint, I like to set up planes using a PPM rx to locate and eliminate any obvious radio issues and after that's completed install the PCM rx and go fly. Setting up with the more susceptable receiver helps to weed out stuff rather than cover it up to come back and bite you later if it gets stronger.

Rcpilot

My Feedback: (78)

I've been using a JR652 for YEEEEAAARS on giant scale planes. Granted--none of them are 50% scale.

I just recently upgraded to an 8103.

There are only a few things that I can fault the 652 on:

No Dual Rates or Expo on the rudder. Not necessary--but nice to have.

No way to mix dual elevator servos correctly. You can mix dual elevator servos--but you can't get both of them to respond to trim inputs from the TX. Simply not possible with the 652. Requires a Matchbox or similar device.

It's a power hog. My stock niCD battery wouldn't last 5 flights. I switched out to a 1500mah niMH battery and can fly for about 2 days on a charge.

But, if you can work around that stuff--it's a fine radio for GS planes.

I still use it, but not on GS anymore. I've got the 8103 for my GS stuff. I use the 652 for my hot rod trainer, and my 40 size 3D planes.

I personally do not think you need PCM. I've been flying PPM since the first day in this hobby. Never saw the need for PCM.

flyierjon

so pcm is a matter of choice??? thanks for the info RCPILET! it really helps. so with what you said about a match box, would that allow me to trim 2 servos like for example on the elevator or rudder? or any other channel???

rcblimppro

I can't imagine trying to put in a decent sequence in without having expo on rudder. A 1/2 scale Pitts is going to have about 105"-110" wingspan. Imagine the length of an extension that has to run from the RX in the fuse up to the cabaines and then down the wing. My guess is that there will be some flying wires involved as well. IMO PCM is not an option, but I do like Pat's idea of running it up and doing all the range checking with PPM. That way you could optimize the setup then install the PCM RX and be that much better off. Personally I would look into a Smart Fly power expander as well.


Shawn Berkheimer

R/C Blimp Productions.com

flyierjon

that is what i think im going to do, get it all set up and everything with ppm and then before the first flight switch it over to pcm. please explain to me what a smart fly power expander is and how much do they cost!?!?!

THANKS TO ALL OF YOU FOR YOUR HELP!!
Jon

Rcpilot

My Feedback: (78)

Jon:
A JR Matchbox is a device that allows you to run 4 servos off 1 channel.

For example:
If you have 2 Elevator servos--you plug them into the Matchbox and then plug the Matchbox into the Elevator port in the receiver.

What you get is the ability to set the center points of each servo. You get the ability to set the end points (travel) of each servo. You get the ability of reversing the direction of 1 servo.

A Matchbox can handle up to 4 servos. So, if you've got 4 ailerons servos--then you just plug them all into the Matchbox and then plug the Matchbox into the aileron port in the receiver. Adjust all the servos for best performance.

You can even power the Matchbox with it's own battery.

A Smart fly power expander is a device that allows you to use more than 1 servo on a control surface. It also has isolated servo and RX power.

www.smart-fly.com

Jon:
Don't take this the wrong way, but allow me to make an observation.

If you don't know what a matchbox or a power expander is--are you sure that your ready for a 50% scale Pitts?

Most giant scale fliers have used the matchbox or at least know what they are and how to use them. Also, most giant scale fliers will know what a power expander is and how it works.

If you don't know what these devices are--then how much experience do you really have with giant scale planes?

If this is your first giant airplane--then I suggest you step back and start with something smaller and less complicated than a 50% scale Pitts. Thats big $$$, big responsibility, and big danger--when your dealing with a plane that big.

Just a suggestion. Not meant to offend.

flyierjon

RCPILET. no offence taken. but I also am a fast learner. I am doing this project because i know i can do it. No matter what it takes. I am always a safe radio control pilot/ airplane builder. I have knowledge of most things dealing with large scale airplanes, i helped a friend build and fly an exact to scale 1/3 scale piper cub. Instead of using a match box or a few of them i am getting a dual power interface. This will be better than a match box.

With any project, I pick up on things quickly. If i need help or have questions i have people i can go to for help on these subjects, including on here. The people on here are great. And im always learning.

One of the main reasons im doing this 1/2 scale pitts project is because this plane was the dream of the guy who got me into the hobby and he has died recently in a bad car accident and this is my memorial to him! I hope that is a good reason and i am willing to learn or do what ever it takes to make this a reality!!

Volfy

My Feedback: (23)

Why would PCM matter if what you're worried about is long servo extensions? PCM or PPM, by the time the RX converts the incoming RF signal to individual servo position for each channel, it all becomes the same pusle width signal that all RC servos understand.

Problem with long servo extensions degrading servo signal quality (either by voltage drop or RF noise pickup) can be solved with twisted leads, larger wire gauge, RF chokes and/or signal amplifers.

If you are worried that long servo extensions might act as antennas radiating RF noise, it is only somewhat of a problem when they are run in very close proximity along the entire length the RX antenna wire. This applies mostly to rudder and elevator servo leads run inside the fuselage, not aileron extensions. Even then, the effect usually amounts to some very minor servo glitching and maybe a slight reduction in reception range. Having a PCM RX does help minimize this. Still, it isn't much of anything to write home about and not really something that would serious compromise operational safety. Anyhow, it is easy enough to separate the servo leads and RX antenna inside the fuselage, especially a 1/2 scale Pitts!

Whether to use PCM vs. PPM is a whole 'nother can of worms. I'll stay out of that one.

rcblimppro

The length of the servo leads in themselves is not an issue. Its the fact that they will be placed relitivly close to flying wires and then add in the ignition of a big twin. I would be willing to bet that under these conditions you will not get an adequate range check with PPM. Twisted wires will help and I always use them in all my airplanes but experiance tells me that PCM is the way to go. With PCM you will also have failsafe that can be set to engine off in case there is ever an issue. A Power Expander will Buffer out any RF that may get into the servo leads and will deliver more current to the servos than the RX would be able to do. Something I would consider because of the length of the leads. One person that would be good to direct questions to would be Bil Hemple as he does have an Exclusive Model 50% Pitts. Attached is a pic of a Power Expander in my 40% Extra.


Shawn Berkheimer

R/C Blimp Productions.com

flyierjon

Thank you RCblimppro. I am going to be using a power expander from smart-fly. im just trying to figure out how i can hook up 4 battery packs to it instead of just 2. and along with the expander i will have a voltage regulator and a bat share.