Salvage and Reprogram the AR636A Receiver from Eflite Planes with SAFE®

The Plight

Many Eflite foamy planes sold by Horizon Hobby come with SAFE® technology based on AS3X® receivers from Spektrum. While Spektrum’s AS3X receiver can be purchased separately and installed on any planes to give them 3-axis gyro stabilization, Horizon Hobby has coupled the AS3X receiver with most of their Eflite foamy planes, with additional programming, to make their planes more accessible to beginner flyers. The receiver/plane package is known as SAFE®. And the main features of SAFE® include the famed “Panic” button, as well as beginner-friendly receiver-side flight modes.

planeThese SAFE® features annoy veteran flyers to no end, and render most of these fine aircraft useless to experienced flyers, unless the $80 AS3X receiver is replaced with a normal receiver. Take the NIGHT VisionAire that I can’t stop flying, for instance. This is an exceptional 3D plane that delivers great value for the price. But its built-in receiver forces the pilot to choose either the Precision flight mode with intermediate gyro gains and ridiculously low throw rates, or the 3D flight mode with very high gyro gains, and 100% control surface throws. The gyro stabilization can never be turned off.

Perhaps Horizon Hobby can’t fathom why anyone would want to fly their VisionAire with low/zero gyro gains and very high throw rates, or high gyro gains and low throw rates. The end result is that one can never fly the VisionAire at very high speed without the plane swimming in the air like a dolphin. And one can’t have a relaxed cruising experience under strong winds.

Sarcasm aside, I do understand why gyro gains are coupled with expo and throw rates in these receiver-side flight modes. Often beginner pilots have nothing more than the free DX5e that comes with their plane. So Horizon Hobby must make it such that pilots with a dumb radio can still fly these sophisticated planes. Receiver-side flight mode is one way to achieve this goal.

The Seldom-mentioned Solution

AR636A picture IMG_1356 Cropped AdjustedBut it turns out that most of these planes actually come with an extremely capable $80 Spektrum AR636A Sport receiver, and it can be reprogrammed using just a smartphone and a special programming cable. You can change gyro rate gains, as well as heading gains. You can completely turn off AS3X stabilization in any of the three receiver-side flight modes, if you want to fly your plane without gyro stabilization.

The fact is, Horizon Hobby does not go out of its way to advertise that these supposedly locked-down “AR636A Sport” receivers can be reprogrammed without losing SAFE® features. There isn’t a lot of information online talking about repurposing the AR636A receiver, except on rcgroups.com and some Youtube videos, and only if one knows what exactly to look for.

Many experienced pilots chuck the AR636A and install a new receiver in order to make the plane fly the way they want. What most do not know is that AR636A is simply a normal AR636 Sport receiver with preconfigured parameters and some built-in customization tailored to particular Eflite planes. For instance, here is a version of AR636A customized for the Sukhoi. In replacing the AR636A, not only does the pilot waste an $80 receiver, they also lose Panic mode and other SAFE® features that may come in handy when lending a plane to a newbie.

spma3081 cable pictureThe solution in most cases is a $12 AS3X programming cable, plus a free app called Spektrum AS3X Programmer for one’s smart phone. These are designed to work on normal AR636, AR6335, AR7350 and AR9350 receivers. But they work just fine for the AR636A, too. In fact, the app knows about these custom AR636A receivers – when connected to one, it will properly set the receiver type to “AR636 SAFE” which is not a choice one can explicitly set in the app under normal circumstances.

Identify Your Receiver

AR636A picture IMG_1356 Cropped Adjusted AnnotatedNot all Eflite SAFE® planes come with AR636A. The VisionAire and Carbon-Z Yak 54, for instance, in 2014 shipped with the AR635 receiver. While this was a fine gyro-stabilized receiver, it could only be reprogrammed using transmitter sticks. Another example is the Apprentice S 15e – it comes with a one-of-a-kind receiver.

If you already have an Eflite plane, make sure the receiver looks like this picture. Note the extra “A” at the end of the model number, the “Sport” designation, and most importantly the “PRG” label by the bind port which serves as the programming port.

But even then there is no guarantee that your receiver is “easily” reprogrammable. Page 428 and Page 429 of the AS3X receivers thread on 2016-07-28 clarified the issue. As of this date, only a few AR636A receivers can be directly reprogrammed using the app. Most previous AR636A receivers, even if they look identical to the above, must be connected via an USB cable to a PC, and have its receiver firmware flashed, in order to unlock the receiver for reprogramming.

Reprogrammable receivers from the appAt this time, it seems like one reliable way to find out if the receiver from your plane can be reprogrammed without requiring a firmware flash is to look at the Programmer app. In the New Model page, planes with reprogrammable receivers are listed explicitly.

If you search in rcgroups.com, you’ll find enthusiasts discussing AR636A reprogramming, such this discussion in the Night VisionAire thread around 2015-10-29. Note that, like this article of mine, no online information can be trusted alone. And not all information from the past you dig up will still be current and applicable by the time you read it. That discussion from 2015, for instance, makes one believe that wiping out the receiver firmware via a PC and losing the panic mode in the process is the only way to reprogram the AR636A from the Night VisionAire. That is not true, or at least no longer true as of the writing of this article (2016-07). Use the app itself as the definite source of truth.

If you are considering buying an Eflite plane, and want to make sure you can reprogram its receiver, with or without the need to first flash the firmware, start with the bindnfly.com page which lists all planes. For some planes it lists their exact receiver model number. These are planes listed as having the AR636A receiver:

  • NIGHT VisionAire
  • Pulse™ 15e
  • P-47D Thunderbolt
  • Rare Bear
  • FJ-2 Fury

The page alone is not to be trusted, however. It lists the ParkZone® Sukhoi SU-29MM as having a normal AR636 receiver. I have the Sukhoi, and I know it comes with a locked-down AR636A Sport receiver. And AndyKunz from Horizon Hobby confirmed on rcgroups.com that no Sukhoi receiver can be reprogrammed without firmware flash. Now you know what keywords to search for online, when researching a plane. Do your homework first.

Learning to Reprogram the Receiver

So you’ve got the AS3X Programming Cable. And you’ve downloaded the Spektrum AS3X Programmer app. Furthermore, your receiver does not require firmware flash. Where do you begin now?

If you are relatively new to RC flying, you should start with the AS3X page at Spektrum. Just remember that almost everything they write about the AR636 applies to the AR636A. Spektrum has a 16-video tutorial series on AS3X on Youtube, designed for users who buy an AS3X receiver to install on their own planes. It is useful to go through the entire set if you are new to the scene, starting with Spektrum AS3X Step 1: Transmitter Setup.

But for the purpose of reprogramming AR636A, what you need are Step 13, 14 and 15.

Spektrum AS3X Step 13: Exponential and Dual Rate explains how to set expo and dual rate on the receiver, in one of the three receiver-side flight modes. Honestly, I recommend that you change expo to 0% and D/R to 100% in all receiver-side flight modes. I set up expo and D/R on my radio instead. This allows me to decouple expo and throw from gyro gains. Recall that the bundled expo, throw and gains were what caused pilots grief in the first place with these locked-down receivers.

Spektrum AS3X Step 14: Gain Adjustment explains gyro rate gain and heading gain very well. You must watch this video. You should note that there is a small difference between AR636 and AR636A. SAFE® planes hijack the heading hold feature of AR636A to implement the Panic Mode. When you hold down the panic button on the radio, it forces the receiver into heading hold mode, to move the plane back to a stable, upright orientation. So you will want to leave the heading gain settings in N/A, if you want to keep the panic mode. You can, however, freely change the rate gains.

Spektrum AS3X Step 15: Relative Gain Settings is the key to understanding how to find the right gains for ailerons, rudder and elevator for different flying scenarios. This only applies, however, if you have a modern Spektrum radio such as the black DX6, DX9, DX18, etc. that support telemetry, and is updated with modern firmware. Your AR636A receiver is able to send back its expo, D/R and gain settings as telemetry data, to the transmitter. The transmitter then allows the pilot to dial up and down the relative gain, on the radio, while flying the plane, until the right gain is achieved. Once the right gain is found, you read the “actual” gain shown on the radio, and reprogram the absolute gain on the receiver to match what you found.

Actually Reprogram the Receiver

So you patiently learned to reprogram the receiver. And now you are actually going to do it. Just know that you are doing this at your own risk. No one can save you if you screw up.

Wiring the programming cableFirst remove the propeller from your plane. You never want to program your receiver with your propeller on the plane. Most tutorials advice you to remove your receiver, and power it with a battery pack for programming. But no one does this in practice. Everyone just plugs a flight battery pack into their plane, and power up the receiver that way. So you want to remove the prop. See how John Adams does it in this picture? Connect the programming cable to the bind port of the receiver as shown.

Power up your receiver. And launch the programmer app on your phone.

Don’t do anything in this app yet. Do not follow the initial setup instruction from the Spektrum video. Instead, just connect the programming cable to your phone. The Spektrum app will detect your receiver, and prompt you to create a new model FROM THE RECEIVER. This is the key to your success. You must let the app download current factory settings from the receiver to your phone. The app apparently tracks the model of the receiver it connects to, and it will not allow you to synchronize model changes you make in the app to the receiver, if it did not create this model from the receiver in the first place. For the Night VisionAire you will see default factory settings of AR636A reflected in the app. Flight mode 1 and 2 are identical.

App FM1   App FM3

You should take this time to name the auto-created model. And from the Settings pane, you can email this model to yourself. Save it as a backup, so you can go back to factory settings later, if you wish.

In the Settings page you’ll find that the app sets the “receiver type” for this model to “AR636 (SAFE)”. This is not a receiver type you can normally choose in the app, if you were to create a model file anew, without synching it from the receiver. The app apparently knows that it is dealing with a special, customized AR636. Note how it sets heading gains to N/A? The app knows that SAFE® uses heading hold to implement panic mode.

You can now tweak rate gain, D/R and expo on each axis. And you can try it out in real-time, too. After you tweak a value, the app will automatically synchronize it to the receiver. You can move the sticks on your radio to see these changes right away. Just remember two things. First, for the AS3X to engage in the receiver, you must first throttle up past a certain percentage – it’s a safety guard. So if the plane doesn’t seem to respond to your gain changes, make sure you have activated the AS3X once by throttling up, and then back to 0% throttle. Secondly, you have already removed the prop, right?

All I wanted was a cruise mode with less pitch rate gain to avoid the porpoise-like motion. I also did not want the receiver to impose any expo and throw constraints on any axis. So I edited flight mode 2 to make it so.

I also wanted a mode where stabilization is completely turned off. So I made the same changes as above to flight mode 1, and in addition zeroed out all rate gains.

Now I have three flight modes: 1. no stabilization, 2. low gyro stabilization, and 3. high gain for 3D flights.

fred-night-visionaire-spektrum-as3x-programmer-settings-2017-july

That’s it for today. Fly responsibly. And try not to make garbage.

ps: 2016-07-26. Eflite is about to make available a second generation Sukhoi SU-29MM. This is the first time Eflite publicly states that a plane with the AR636A receiver can be tuned using the programmer app on a phone. But there is scantly any additional information on this detail. Instead, the gen-2 page and video go to great lengths to explain how pilots can now easily disable the Panic mode at binding time. I think Eflite is solving a non-issue – no one cares about disabling the panic mode. People want to learn to free their planes from the tyrannical regime of bundled receiver parameters. Instead of releasing a gen-2 Sukhoi with a disabled panic mode, Eflite and Horizon Hobby can better engender enthusiasm by simply providing proper documentation on reprogramming of AR636A receivers in existing planes. That said, this gen-2 plane probably comes with a receiver that can be programmed without firmware flash. I expect this plane to show up in the known plane list in the Spektrum Programmer app soon.

ps: 2016-07-28. There is apparently a new set of planes with the so-called “SAFE Select Receiver” (Spitfire and Timber). These are advertised as easily reprogrammable. I take it to mean that you don’t need to flash the firmware and lose SAFE features. Perhaps the Sukhoi Gen 2 comes with this receiver as well.

About Xinhai Dude 辛亥生

The name Xinhai Dude 辛亥生 is a pun in Chinese, as it means both “he who was born in Xinhai” as well as “he who studies Xinhai”. I had an ambitious plan to write something about the great Xinhai Revolution of 1911, thus my blog https://xinhaidude.com. But after an initial flurry of activities the initiative petered out. One day I will still carry it through. But for now, this website has turned into a conglomerate of my work on various topics of interest to me, including travel pictures, RC model airplane flying, ice skating, classical music composition, science fiction short stories, evolution and atheism.
This entry was posted in RC Planes and tagged , , , , , , , . Bookmark the permalink.

42 Responses to Salvage and Reprogram the AR636A Receiver from Eflite Planes with SAFE®

  1. Koosha says:

    I just bought an E-flight T-28 bfn 1.2 with AR3X AR636A
    I follow the instruction and put them together and bind the receiver with my DX6i spectrum radio
    Now all control surfaces work as normal but in page 10 of instruction manual said something about checking the AR3X if it is active or not which is tilting the plane up an down left and right and so on in this point I realized that my control surfaces does not respond to those movement
    This means theAS3X is not active (as I understand from manual)
    I don’t know what to do now
    I wonder if anybody had or have this problem and any chance to fix this?

    • Search for throttle or prop in this article. For the stabilization to engage you must first throttle up. It’s a safety mechanism. But you need to be very careful that your prop won’t cut you nor fly the plane away from you when you do this. Normally one holds the tail of the plane, or stands with the horizontal tail stabilizers wedged against the heels. If you are not sure please google for videos before you try this.

  2. FirstJoan says:

    I see you don’t monetize your page, don’t waste your traffic, you can earn additional cash every month because you’ve got high quality content.

    If you want to know how to make extra money, search for: Mrdalekjd methods for $$$

  3. Garland Jones says:

    Good info,,but I need to know how to put safe back on the 636,, any thing

    • Did you remove the heading gain from a SAFE AR636A? Like I wrote, I dared not do that. It looked like the app would let me do that, but I simply did not touch it. If you removed heading gain, do let me know if you figure out how to program it back. I have no idea.

  4. Tony says:

    I have anAR636 bought from a local hobby shop. it is not programmed for anything. I have been trying to load any of my models into it so as to enable SAFE.. but i can not get it to work.

    Other than sending it back to HH any ideas?

    • I have never had an unlocked, normal AR636. I don’t know how to help you. But if you recall my experience with the locked-down AR636A, I had to download the model directly from the receiver to the phone app. And the app associated the stored model to the receiver. I couldn’t create a SAFE model from scratch.

  5. Sam says:

    Why so complicated! All I want to do is fly the plane not become a software engineer..my icon a5 ar636a safe plus is off. No correction from wind or overbanking or anything…can’t figure out the issue. If only it were as easy as a red switch! Only it’s software jargon

    • Late reply as usual fr me. Sorry. I don’t have the Icon. Hit it looks like you probably bound the radio normally which would disable SAFE.

      • Koosha says:

        I just bind to my radio normally all control surfaces respond to my radio normally
        But it doesn’t respond as safe mode when I tilt the plane in the ground test
        What we can do now

  6. Anonymous says:

    I will be using a PC with the downloaded Spektrum programmer since I don’t have a smartphone. Will this method present any limitations to programming receivers?

  7. Don says:

    Excellent article. Of course by now you probably know you can buy an off-the-shelf AR636 and send it back to HH and they will program it, for a fee, to one of their stock SAFE setups that you specify.

  8. kiwi-craig says:

    do you know if the app works on the blade 200SRX helicopter receiver, its listed as an AR636A many thanks

  9. Mark Ellis says:

    Thanks for all your hard research. All very useful and well presented. I thought I would share my experience. I purchased an AR363a on a well know auction site not knowing it had been extracted from a BNF model. All seemed good as it bound with my new Spektrum DX6 and the flying controls worked after a fashion. So I purchased an Audio Updater which would not connect or give me a serial number so that I could register it. So I then purchased the USB interface cable…. I was able to connect with this cable (after applying power via a BEC) and download the Serial number which was then not recognised by the Specktrum RC product registration service. BINGO the Device was shown as Sukhoi at this point I had not found your excellent work, so lesson learned I now have 2 expensive cables and no result. I suspect Spektrum deliberately or otherwise use the same product Number on discreetly different kit to provide uncertainty to persuade modelers to chuck the recovered RX or not to buy second hand ones. All this in the hope we will buy new….. they should be happy with the money they make on the cables because I cant afford to buy a new one now ☹

  10. Wolfgang says:

    Thanks for the great summary.
    I have a gen 1 SU29 mm and am suffering from oscillations in 3D mode and ridculosly small throws in precision mode which cannot be overturned on the sender side. I do not care about SAFE at all. I just want to fly the plane like a grown up guy with decent throws …

    Hence I tried to optimize the AS3X settings of my AR636A. Here is the result:
    – The mobile app would not detected the receiver,
    – the Windows Updater would detect it and show the serial number
    – the Windows Programmer would not connect to the receiver
    Hence I tried to register the receiver to download the firmware updates.
    Unfortuantely the Spektrum website would not allow registering the receiever.

    Any hints?
    You wouldn’t have a firmware update file for the AR636 that you could make available?

    Thanks from Munich

    Wolfgang

  11. Gary Davidson says:

    Please help…. I have an Eflite Sukhoi Gen 2. The app communicate well with my plane, but during an upload the app crashed. Now i can’t get as3x working. Does anyone have the settings saved for this aircraft who could email then to me?

    • 辛亥生 says:

      I don’t have a Sukhoi Gen 2. My Gen 1 receiver can’t be flashed. I wrote about that here. I also noted my expectations about Gen 2. But I’ve just checked the app store for update to this app. I am on v 1.0.8 (iPhone). And this version hasn’t been updated since Nov 7, 2016.

      So, how did you make the app talk to your plane? Did you choose the “Default (SAFE)” profile, then?

      You need to call Horizon Hobby or Eflite. I found their customer service very professional and customer-friendly. They’ll be happy to help you.

  12. Michael Lee Holmes says:

    I have one of the AR636a receivers and am trying to figure out how to flash the firmware to make it programmable, I’ve tried to register it on the Spektrum website and it keeps giving me the error message that it’s not an AR636 receiver.

    • 辛亥生 says:

      Sorry about the late reply. I have never flashed my receiver. Part of why I went through the trouble of researching and then writing this article is because I did not want to have to deal with flashing the receiver. I didn’t really have a working PC at the time. Flashing was dealbreaker for me at the time.

  13. Isaak says:

    Got new Timber with AS3X on it and AR636A rx. in first 12 flights 3 times at take of plane sharply turn around and hit the ground. I got no control to recover from it. And sure plane broke. Fix it and plane do the same. Found out that AS3X settings for rudder in reverse and at take off time wind or anything else turn plane horizontally it altivate AS3X and make it worse. I did not planning in programing, but tech support says no other way to fix it. Support says if I change direction on my radio, you need to rebind. and I did several time with no result. Only reprogram with my IOS device .
    How hard to reverse rudder direction in AS3X?

    • 辛亥生 says:

      Sorry about the very late reply. The mobile app has a servo reverse setting under the Surface Setup page. Here is what the built-in help says:

      “Reverse. Changes the direction of the servo movement.Servo reversing for the control surface must be done in the application and not the transmitter. The versing setting for all control surfaces (Aileron, Elevator and Rudder) must remain normal in the transmitter.

  14. Rossi Nuccio says:

    Im trying to reprogram my rx that came with my HH Opterra / AS3X 636A. I cant seem to get the IOS cable to work well.Keeps crashing and saying recycle power etc. Any idea whats going on here?

    • 辛亥生 says:

      Perhaps it’s an app vs new iOS issue. Have you upgraded to the new iOS 10.2? When I wrote this article I was on the previous iOS version. I haven’t used this app since then. I have upgraded to 10.2 now. When I have a chance I’ll see if the app/cable still work.

      • Rossi Nuccio says:

        I’m on 10.0.2 Should I upgrade?

        • 辛亥生 says:

          I meant that I was not on 10.2 when I used this app. 10.2 is the latest iOS version. When a new version of the iOS comes out I often see apps crash.

          For example weather underground stopped working. Sometimes you have to wait for the app developer to release a new version of the app. In the case of weather underground I uninstalled the app and reinstalled it. It stopped crashing.

          • Ross nuccio says:

            Thanks very much. I’m getting connected ok now. Just need to figure out how to get a wing to work properly with a DX6i. Anybody have AR636a settings they can email me from the app ;) ??? Thanks.

  15. Eric Filsinger says:

    Thanks so much i’m getting a night vision air and wondering if this will work on my hobby zone Sport cub s2

    • 辛亥生 says:

      Well. I don’t know about the Sport Cub S2. As I wrote on the article, it seemed to me that the only sure way to find out is to look at the “Spektrum AS3X Programmer” app, and see what plane models it officially supports. I’ve just updated this app on my phone, and looked at it. It still shows the same four supported planes: Han5100 P51, Night Visionaire, Ultimate 2 and Crescendo S….

      • Thanks again, please tell me how much D/R and expo your adding on the radio? I have a DX and with 70% D/R and no expo I found it way too sensitive.
        Do you still have the panic function after making these changes?

  16. I possible could you share a screen shot of your final settings? Getting a NV next week THANKs

    • 辛亥生 says:

      Sure. I just did. Reload the article to see new screenshots showing the three modes I programmed for the NV. As I wrote on the article, I zeroed out expo in all three modes, because I programed expo separately on my radio and assigned that to a different switch. I set dual rate on all three modes to 100, because again I programed that separately on the radio.

      So, you see, the only difference between the three modes is simply the rate gain. I have effectively disabled all bells and whistles on the AR636A, except for the rate gains.

      That said… I can tell you that I’ve flown the NV every other two days for almost two months after I wrote this article. I found that I really didn’t need anything other than mode 1 where all rate gains are turned off, under most flying conditions. When it was really gusty, I sometimes switched to mode 3 when hovering. But that’s an exception, not the norm :)

  17. Hamid Sami says:

    what about programming a AR636 without the”a” to make it work like the SAFE? with the three modes and the panic? can you share the inputs?

    • 辛亥生 says:

      I don’t think you can take a stock AR636, and add SAFE to it. If you really want an AR636A with SAFE, buy one online. There are lots of people fed up with the locked-down versions.

      What you want is the opposite of what this article addresses. If you want to arm your plane for a beginner, then even a locked-down AR636A (like the one from the old Sukhoi) will be fine. In that case, pairing gyro gains to control surface throws is desirable for its simplicity. And the beginner will probably never want to turn off gyro assist.

    • No you cant, there is heading programmable but its not exactly the same, Spektrum also does not sell SAFE receivers separately for a reason, they are plane specific!!!!! Some also are locked and can not be programmed

  18. Skip Vedell says:

    Thanks for the detailed explanation. Where do I find the pc app that unlocks my AR636A to make it more tunable. I have the first gen parkzone sukhoi. Thanks

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s