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Dec 06, 2019, 09:46 PM
Captain USCG
Captain.MPN's Avatar

Requesting advise on the Trojan horse


Hello fellow T-28 flyers/owners,

I have been out of the hobby for some time, due to work and life... However, I'm easing my way back in. I picked up a CZ T-28 recently from my LHS, that was pre owned, with a spare set of wings, in the box, as well as horizontal stab & canopy + 4 props.

I have read through both threads, this one as well as the mod thread. which has been great reading material. But.., before I lite this wick, I have a few questions. I use to fly all of my planes with my old Spextrum DX7, and have several older, circa 2010ish receivers. I bound the Trojan to my DX7, After several taxi trials, I just didn't feel comfortable with the old equipment. Then I suppose the bug bit me, so I upgraded to a DX8 gen 2.

I must admit how much has changed in the past 5 years... I'm somewhat uncertain if the DX8 was a good choice, but being adaptable, I'll get it figured out sooner then later I hope

My plane came with a Spektrum AR9350 & 2 remote receivers installed. Flap hinges, Du Bro 2/56 push rods, really the whole bit, besides the stock motor, ESC/BEC & retracts... It has been flown, a few times, having spoken with the previous owner, and others at the field. Rock solid, as per what I was told. It shows as well... Looks like it's never been touched.

To get to my point, I have a CC 20 BEC that is NIB, and for safety measures, I figure I'll install that for the proclaimed retract issue. But my questions are, 1) fly it as is 1st? 2) are the DX8 Gen 2 and AR9350 compatible? & 3) having never dealt with the new safe technology, is it worth even setting that up..?

Any feedback would be greatly appreciated.

Mitchell
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Dec 06, 2019, 10:36 PM
Registered User
Quote:
Originally Posted by Captain.MPN
Hello fellow T-28 flyers/owners,

I have been out of the hobby for some time, due to work and life... However, I'm easing my way back in. I picked up a CZ T-28 recently from my LHS, that was pre owned, with a spare set of wings, in the box, as well as horizontal stab & canopy + 4 props.

I have read through both threads, this one as well as the mod thread. which has been great reading material. But.., before I lite this wick, I have a few questions. I use to fly all of my planes with my old Spextrum DX7, and have several older, circa 2010ish receivers. I bound the Trojan to my DX7, After several taxi trials, I just didn't feel comfortable with the old equipment. Then I suppose the bug bit me, so I upgraded to a DX8 gen 2.

I must admit how much has changed in the past 5 years... I'm somewhat uncertain if the DX8 was a good choice, but being adaptable, I'll get it figured out sooner then later I hope

My plane came with a Spektrum AR9350 & 2 remote receivers installed. Flap hinges, Du Bro 2/56 push rods, really the whole bit, besides the stock motor, ESC/BEC & retracts... It has been flown, a few times, having spoken with the previous owner, and others at the field. Rock solid, as per what I was told. It shows as well... Looks like it's never been touched.

To get to my point, I have a CC 20 BEC that is NIB, and for safety measures, I figure I'll install that for the proclaimed retract issue. But my questions are, 1) fly it as is 1st? 2) are the DX8 Gen 2 and AR9350 compatible? & 3) having never dealt with the new safe technology, is it worth even setting that up..?

Any feedback would be greatly appreciated.

Mitchell
Is this the Gen 1 CZ T28 or the Gen 2?

So to answer your questions

1 - Sure why not
2 - Yes though you will only have access to 8 channels rather than 9
3 - Yes, you have been out of it for a while and will help with confidence
Dec 07, 2019, 12:37 AM
If it flies, I can crash it.
rocketsled666's Avatar
Hmmm. I have a slight different take.

1) The LG is definitely a risk. It's small, but non-zero and no way to predict. If you don't make the LG mod you'll be kicking yourself if there's a problem. It sounds like you know what to do and already have the BEC, so I say do it before you fly it.

2) 8 Channels is enough. You've got 6 for the flight controls and LG, and 2 left over for Flight Mode control if you want it.

3) Not being familiar with SAFE, I would actually caution you not to set it up. You have to get it right, and it's more than just enabling it. If you get it wrong your flight will end badly. A similar caution extends to AS3X if it's not already set up (the 9350 is not the stock RX). Pick a nice windless day to fly it, get a feel for it. Start to experiment with these other features once you're able to handle the airplane. Get them set up and tuned on a windless day, too (and for your first tests, take off without the assists being enabled, get some altitude sufficient to recover if something happens, and then turn them on), and then you can start flying in more challenging conditions and the systems will do their thing and all will be well. Alternately, you could just buy a stock replacement RX and Horizon will have set the gains for you.
Dec 07, 2019, 06:07 AM
Right Rudder
PittSpecial's Avatar
Quote:
Originally Posted by Captain.MPN
Hello fellow T-28 flyers/owners,

I have been out of the hobby for some time, due to work and life... However, I'm easing my way back in. I picked up a CZ T-28 recently from my LHS, that was pre owned, with a spare set of wings, in the box, as well as horizontal stab & canopy + 4 props.

I have read through both threads, this one as well as the mod thread. which has been great reading material. But.., before I lite this wick, I have a few questions. I use to fly all of my planes with my old Spextrum DX7, and have several older, circa 2010ish receivers. I bound the Trojan to my DX7, After several taxi trials, I just didn't feel comfortable with the old equipment. Then I suppose the bug bit me, so I upgraded to a DX8 gen 2.

I must admit how much has changed in the past 5 years... I'm somewhat uncertain if the DX8 was a good choice, but being adaptable, I'll get it figured out sooner then later I hope

My plane came with a Spektrum AR9350 & 2 remote receivers installed. Flap hinges, Du Bro 2/56 push rods, really the whole bit, besides the stock motor, ESC/BEC & retracts... It has been flown, a few times, having spoken with the previous owner, and others at the field. Rock solid, as per what I was told. It shows as well... Looks like it's never been touched.

To get to my point, I have a CC 20 BEC that is NIB, and for safety measures, I figure I'll install that for the proclaimed retract issue. But my questions are, 1) fly it as is 1st? 2) are the DX8 Gen 2 and AR9350 compatible? & 3) having never dealt with the new safe technology, is it worth even setting that up..?

Any feedback would be greatly appreciated.

Mitchell
Mitchell,

1. Okay, you say that you have reviewed the MOD Thread for the Carbon-Z T-28 Trojan then, have you considered placing a Tape (Medical Tape) over the Circuit Board of the Nose Wheel Retract? This Nose Wheel Retract is prone to fail when the RC Flyer decides to fly and land the model OFF from Wet Grass! Here is the consequences of doing so................................
https://www.rcgroups.com/forums/show...T-28-Trojan%21

2. From item #1. don't think you would need any additional device for the Retracts as the Tape will isolate any moisture from the Nose Wheel Retract circuit board. I usually spray a tiny bit of CRC 2-26 pray on the circuit board and using Q-Tip swab to allow for even more protection before applying the Protective Tape. The Mains do not need this as the Circuit board are perpendicular to the wheel travel, however, it would be a good idea to provide protection to them as well.

3. Assuming that the previous owner has flown the model with the AR9350 then, the model has been successfully flown with this Telemetry ready receiver? I myself personally do NOT like any Artificial Stabilization Control in 3 Axis (AS3X), and went with a known regular receiver, the AR8000+SAT. This AR8000 has enough AUX inputs to allow for the dual Power Source for my selected Castle Creations BEC PRO. I would caution you with the any Receiver that has SAFE & AS3X and if you decide to continue to fly then, be very familiar with it and all the programming.

Best of luck!
Pitts
Dec 07, 2019, 10:37 AM
Captain USCG
Captain.MPN's Avatar
Rocket_33 - Rocketsled666 - & Pits,

Thanks for the feedback... I truly appreciate the Camaraderie that fellow flyers provide especially ones like you guys, who have thousands of Posts and the willingness to share your knowledge...

Having flown multiple different aircraft, large scale normally and still have them. Theyíre just a little dusty.

Considering I am as well, I have heard the good bad and the ugly regarding the AX3M technology, and SAFE. Especially when you have never flown with it before.

As per my airframe being gen 1, or 2... Iím uncertain. The previous owner bought it new from the LHS in October, so Iíll assume itís a gen 2?

I fly off pavement, however I will keep a close eye on the FOD and the retracts. I have cycled them probably 30 times, static on my stand, and they have worked flawlessly. However if a failure is going to happen, itís going to happen 👆 up there...

The 2 least important things to a pilot are, runway behind you, and altitude above you.

In the case of this girl, which Iím going to say Iím impressed with. Is the gear binding...

Once again thanks so much, and Iíll let you know how the maiden goes.
Dec 07, 2019, 05:12 PM
If it flies, I can crash it.
rocketsled666's Avatar
My gear worked flawlessly right up until the flight when they didn't and I had to belly land the plane because one main wouldn't deploy... I consider myself lucky, since the real issue with the gear isn't so much that they can get stuck but that the ESC's BEC can be overloaded if a gear gets stuck, causing it to brownout. Brownouts reset the RX, and since it's an AS3X RX it doesn't give control back to the pilot until after it's completed its initialization, and it won't initialize while the plane is moving (in flight). So a brownout in flight equals a no-control crash. That's the reason you want to put the LG on a separate power supply (unless your airplane has the updated LG with over-current protection built in to each retract).
Dec 07, 2019, 11:28 PM
blissinindy
Quote:
Originally Posted by rocketsled666
... Brownouts reset the RX, and since it's an AS3X RX it doesn't give control back to the pilot until after it's completed its initialization, and it won't initialize while the plane is moving (in flight). So a brownout in flight equals a no-control crash. That's the reason you want to put the LG on a separate power supply (unless your airplane has the updated LG with over-current protection built in to each retract).
Rocket, the Rx won't re-establish control in the air and quickly?? Yikes! this has certainly a priority for HH since the AR500 days ... We know the RX (or TX) can distinguish re-link from first link - blinking light displayed ... So fast initialization on re-link should be possible ...

This is what the AR-636 manual has to say:
How QuickConnectô Technology Works
ē When the receiver voltage drops below 3.5 volts, the system ceases to operate.
ē When power is restored the receiver immediately attempts to reconnect.
ē If the transmitter was left on, the system reconnects typically in about 4/100 of a second.

QuickConnect with Brownout Detection is designed to allow you to fly safely through most short duration power interruptions, however, the root cause of these interruptions must be corrected before the next flight to prevent a crash.

NOTICE: If a brownout occurs in flight it is vital that the cause of the brownout be determined and corrected.
What have you found in using the RXs?

Thanks!!
Dec 08, 2019, 12:50 AM
Right Rudder
PittSpecial's Avatar
I believe Rocketsled is trying to say that your model WILL CRASH assuming you don't have a External BEC such that a retract or retract pair is pulling lots of current and does NOT allow the minimum Voltage to recover the Receiver.

So, YES, the model will crash in the case of an unprotected situation when retract will just for whatever reason will pull large amounts of Current and the minimum Voltage to allow the Receiver to function is no longer available and this is mostly on landing when you deploy the retracts and something UGLY happens to them.

In my model's case (while in the hands of the previous owner) the unthinkable happened and the Nose Wheel Retract started to catch FIRE and burned a hole on the Plastic Nose Wheel Holder for the Retract! See pictures from the link I provided in my previous post.

I believe the previous owner of my model was extremely lucky and was able to land the model even though it was technically on FIRE!
Last edited by PittSpecial; Dec 08, 2019 at 01:02 AM.
Dec 08, 2019, 02:30 AM
If it flies, I can crash it.
rocketsled666's Avatar
Quote:
Originally Posted by blissinindy
• When the receiver voltage drops below 3.5 volts, the system ceases to operate.
• When power is restored the receiver immediately attempts to reconnect.
I know. But I've always had a couple of problems with this. They don't say how low the voltage can drop and still do this "speedy" recovery, and "reconnect" isn't the same thing as "reinitialize". There's got to be a voltage below which the RX behaves like it's just been powered up (and it's going to be greater than 0V). In this situation, the airborne airplane will refuse to grant control until AS3X initialization completes. And the radio connecting is required for AS3X initialization to start. Saying it connects doesn't say it won't need initialization afterward. But note - I do not know these things, I have not bothered to check since I modded my plane and now it doesn't matter.

Since my plane never crashed, and I never saw anyone else's. I can only go on what has been described, and that's been loss of control coincident with deploying or retracting the gear. Whether that means the RX never reinitialized or it means the power never recovered sufficiently to get out of brownout mode is anyone's guess. The ESC BEC is 5A. It's driving 6x full size servos plus the retracts. The retracts draw a few 100mA in operation if they don't get stuck. I measured mine when I set up the separate BEC power system and a retract draws 2.5A when jammed. So with a jammed retract drawing 2.5A, you've only got 2.5A left over for 6 large-ish servos. That's not a lot of juice.
Last edited by rocketsled666; Dec 08, 2019 at 03:17 AM.
Dec 08, 2019, 10:39 PM
blissinindy
Quote:
Originally Posted by rocketsled666
I know. But I've always had a couple of problems with this. They don't say how low the voltage can drop and still do this "speedy" recovery, and "reconnect" isn't the same thing as "reinitialize". There's got to be a voltage below which the RX behaves like it's just been powered up (and it's going to be greater than 0V). In this situation, the airborne airplane will refuse to grant control until AS3X initialization completes. And the radio connecting is required for AS3X initialization to start. Saying it connects doesn't say it won't need initialization afterward. But note - I do not know these things, I have not bothered to check since I modded my plane and now it doesn't matter.
Rocket, you've raise a very important point!! We could do some experiments to confirm behavior, but it would probably just be easier to call Horizon

I'm sure you remember early on in the DSM2 introduction timeframe, reboot after brownout took over a second. Horizon received complaints on that and re-acted, introducing QuickConnect. I'd be really surprised if they didn't cover the same scenarios in AS3X receivers. The receiver light flashes when this happens - it knows, even when you completely disconnect the battery and then re-connect. As an embedded SW guy, off the top of my head, I can see ways to implement this desired behavior for an AS3X receiver without need for continued voltage (at any level) on the Rx end. If I can come up with a few ideas that quickly, I'm thinking the experienced folks at Horizon who've (hopefully) put some real time in on this can (much) better that

Quote:
Originally Posted by rocketsled666
... I can only go on what has been described, and that's been loss of control coincident with deploying or retracting the gear. Whether that means the RX never reinitialized or it means the power never recovered sufficiently to get out of brownout mode is anyone's guess. The ESC BEC is 5A. It's driving 6x full size servos plus the retracts. The retracts draw a few 100mA in operation if they don't get stuck. I measured mine when I set up the separate BEC power system and a retract draws 2.5A when jammed. So with a jammed retract drawing 2.5A, you've only got 2.5A left over for 6 large-ish servos. That's not a lot of juice.
Based upon all the valuable info in this thread, I'm thinking you and others measured even more than 2.5A for a truly stalled retract. The amperage went up until the retract moved, the Rx browned out, a fire occurred or more than one ... :: A stalled retract drawing enough current to brownout the receiver (or enough current combined with servo movement), would just throw things right into brownout again when the receiver came back up in QuickConnect mode and resumed commanding the retract (and the servos) ...

Again, you make a very good and scary point. Really worth a ask of Horizon!! I'm hoping QuickConnect takes care of this scenario, which, if you think about it, aligns with the original scenario it was intended to correct ...

Edit

I sent a message to Horizon. let's see what we hear
Last edited by blissinindy; Dec 08, 2019 at 10:56 PM.
Dec 09, 2019, 09:50 AM
fighter or target, which r u
paladin-34's Avatar
Quote:
Originally Posted by Captain.MPN
Rocket_33 - Rocketsled666 - & Pits,

Thanks for the feedback... I truly appreciate the Camaraderie that fellow flyers provide especially ones like you guys, who have thousands of Posts and the willingness to share your knowledge...

Having flown multiple different aircraft, large scale normally and still have them. Theyíre just a little dusty.

Considering I am as well, I have heard the good bad and the ugly regarding the AX3M technology, and SAFE. Especially when you have never flown with it before.

As per my airframe being gen 1, or 2... Iím uncertain. The previous owner bought it new from the LHS in October, so Iíll assume itís a gen 2?

I fly off pavement, however I will keep a close eye on the FOD and the retracts. I have cycled them probably 30 times, static on my stand, and they have worked flawlessly. However if a failure is going to happen, itís going to happen 👆 up there...

The 2 least important things to a pilot are, runway behind you, and altitude above you.

In the case of this girl, which Iím going to say Iím impressed with. Is the gear binding...

Once again thanks so much, and Iíll let you know how the maiden goes.
captain.mpn if you want to fly the plane unprotected put the gear down and then pull the retract plug from the RX. fly with the gear down. I did it for the first ten flights,

Joe
Dec 09, 2019, 11:41 AM
Right Rudder
PittSpecial's Avatar
How about supplying better retracts and separate controller ?
Dec 09, 2019, 10:44 PM
If it flies, I can crash it.
rocketsled666's Avatar
There's nothing overtly wrong with the retracts themselves. It's the switches used for the end-stops. My mod included both a dedicated BEC just for the retracts, and the modification of the retracts to use the JP controller, which is current-limiting. The V2 T-28 replaced the V1 LG with ones that eliminated the switches and replaced them with current-limiting control.
Dec 12, 2019, 06:44 PM
Registered User
so the retracts on the site for replacement are different than the original ones offered?
Dec 12, 2019, 09:34 PM
If it flies, I can crash it.
rocketsled666's Avatar
I couldn't say for sure. But probably.


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