600 My T-Rex 550 Rebuild

[Heliman450]

Hi all! I was looking for a section to publish my thread covering the rebuild of my T-Rex but as we don't seem to have a crash/rebuild area then I think here's fine. I'm not quite so knowledgeable as Steve to do mixing and matching of parts from different helis (yet) but my focus will be on building in strength. Therefore, I've been looking into the pricing for a conversion to DFC as it's a simpler design, has a 10mm main shaft and also seems to include a turn-buckle arrangement for adjusting the pitch and looks pretty good, too.

I was tempted towards a super cool looking 3-bladed head but as I still don't feel inclined to go for the added cost of a crash just yet (twice as much as the DFC plus an extra blade). I brought the heli back from my workshop to do a download of the flight data files from the Spirit Pro as suggested by Steve (never did it before). Any other suggestions welcome as no order placed yet.

I was preparing my list using Shop.Align.com.tw as the source. Any feedback on how efficient they are on delivery?

Next job is to transfer the latest firmware update over to my Jeti DC-14 Tx. as I have been receiving a message from it for some time now. I downloaded v4.0 this morning and will replace my v3.02. I'm hoping to lift my game overall through the next couple of weeks and return with a revitalised heli to video with my new camera (if they deliver in time ).

Bye now!

 

[Smoggie]

Phil,

I hope the repairs are not as bad as it first looked. FWIW main shaft diameter is common accross all the 550 and 600 Trex helis (10mm). The DFC is the same as the rest. Main shaft length however does change so if you did go to DFC you I think you would need the shorter main shaft (part # H60243T). You already know what i think of the DFC head and FWIW Align have dropped it from all their latest models, but it's your call.

Anyway, I happen to have a complete DFC head with grips and main shaft, links and everything if you were interested. It's like new. I also have the DFC swash which I was hanging onto as a spare but I dare say I'll never use. This is what i took off my own 600 Pro DFC after converting in the opposite direction to what you are thinking about!

Personally I'd not bother with a three blade head. Other than the novelty value and aesthetics I dont think there is really any significant advantage in running one and you generally lose a fair bit of flight time... But this is coming from someone who has only read reports on them by others I've never used one, so take it for what it's worth.

 

[Heliman450]

Hi Steve, I've decided against the 3-Bladed head on the grounds of cost as I mentioned.

I haven't measured my main shaft diameter but I was expecting it to be 8mm as I've been using my alignment tool as it came from the box. I read somewhere that there's a sleeve inside the tool that must be removed to use it on the 700/800 with the 10mm shaft so have only assumed that the parts I've seen are bigger than on my 550.

If you're wanting to offload your bits, then maybe we can exchange some ideas on how to achieve it via a 1-2-1 message through the Forum. I'll get in touch.

Cheers!

 

[Smoggie]

The 550 and 600 use a 10mm shaft, the 700 uses a 12mm shaft.

 

[trainrider06]

Hi Phil, you have the correct area that you posted in.
Very sorry to hear about the crash, as the old saying goes, gotta get back on the horse.
Hopefully damage is minimal, and she's up and going soon!

 

[Heliman450]

Hi all! I was prepared to crash the heli as I was feeling that it was due a good overhaul anyway and I was spending a bit too much time 'perfecting' my hover and simply taking my time. No worries there, I now know why it crashed so here goes......

The heli lost signal as recorded in the flight log of the Spirit Pro. I'd already come to this conclusion myself as I was doing an inspection and reflecting on events. One of the pitch control arms has a bent ball link so the turn-buckle must have been in place at the time of impact and the fact that I couldn't find them was just a coincidence. Who knows in which direction they went and without a metal detector, I'm never likely to find them in the field.

So why did it happen? As I spent so much time using the heli within a very restricted window of operation, I didn't turn to keep it directly in line of sight and it just flew too far over to my right and went out of the signal volume of the Tx. I've asked Jeti if they have a diagram to show what this looks like but up to now they haven't responded.

A lesson learnt for the future!

Steve has come up trumps with a newish DFC head and we're sorting out how to do the deal. That takes care of the major cost items so it just needs me to get the bearings, blades etc. I checked out the servo operation and all seem to be operating smoothly throughout their full range. The battery ('C' from A-D) was quarantined for a short while until I got back in the car and has taken a cycle without any problems.

Depending upon the time to get all the stuff together, I'll be back on my horse asap

In the meantime, I need to spend some simulator time improving my auto rotations.

 

[Smoggie]

You shouldn't (if all was working ok) have gone out of range Phil. The antenna on 2.4GHz transmitter is non-directional so it transmits pretty much with equal strength in all directions. Some 2.4GHz Tx's have a 'hole' immediately in line with the antenna where the signal is weaker but the better transmitters these days (including Jeti) have two or more antenna so there is no 'hole' at all. Assuming no solid objects come between you and the heli then range should be 'out of sight' in any direction. For sure I've personally flown planes to the point that they were 'specs in the sky' without any reception problems.

If the log is indicating loss of signal then there is a problem but range in itself isn't the cause of the problem. Usually where there are reception issues it's the receiver end that's at fault. It could be placement of the antenna on the heli is leading to masking the signal (you need at least two antenna on a large heli placed so at least one is in line of sight at all times). Or it could be some other issue such as the voltage supply to the receiver dropped too low and cause reception to be lost (though low voltage should have been logged).

Can you post the log data?

 

[Heliman450]

Hi Steve, the flight log is on my small notebook, which I just packed away for the evening. It's not the most interesting of things but I'll dig it out and post it soon and you can give me some feedback on it. For example, I think it's showing longer than I was flying on that particular occasion and I'll need to check the manual for what it says. I also think the date/time isn't correct. It seems to be getting a reading every 10 seconds and holds its last log, which presumably is replaced each time the Tx. is switched off and then on again, the previous log being lost if not recovered.

This afternoon, I bought some of my bits and ordered up some that they don't have in stock. How's your shipping list coming along? One of the things I was intending to do was to return to the M0.6 tail rotor drive gears but they're telling me that the bevel gear isn't available any more do you think that's true? I didn't see it on shop.align.com.tw when I was there yesterday. I'll trawl around a bit and if I can find it somewhere I'll see if I can buy multiple units as they're very vulnerable items.

Talking of the tail, I got delivery of the skids a couple of weeks back but only got round to fitting them just before my final session. The tail-fin now stands 55mm clear of the ground. A big improvement on 7mm and as stated here it lifted off perfectly but didn't touch the ground once when setting down.

That's it for now....... off to watch some Olympics.

 

[Smoggie]

I'm going out to check my spares bin tonight but other than the head assembly and 600 length tail boom parts i probably dont have much of interest. The boom may be more expensive to ship than it's worth due to 'oversize' length. I'll contact you.

The TT gears are all available, dont believe them if they say otherwise. The old style white ones have been replaced by the new black ones but they are directly interchangeable. If i were you I'd keep the Mod 0.6 auto gear and tail drive layshaft because they give a higher RPM tail, that's preferable (better tail hold) to the later M0.8 gears which are optimised for sky high headspeed.

 

[Heliman450]

You shouldn't (if all was working ok) have gone out of range Phil. The antenna on 2.4GHz transmitter is non-directional so it transmits pretty much with equal strength in all directions. Some 2.4GHz Tx's have a 'hole' immediately in line with the antenna where the signal is weaker but the better transmitters these days (including Jeti) have two or more antenna so there is no 'hole' at all. Assuming no solid objects come between you and the heli then range should be 'out of sight' in any direction. For sure I've personally flown planes to the point that they were 'specs in the sky' without any reception problems.

If the log is indicating loss of signal then there is a problem but range in itself isn't the cause of the problem. Usually where there are reception issues it's the receiver end that's at fault. It could be placement of the antenna on the heli is leading to masking the signal (you need at least two antenna on a large heli placed so at least one is in line of sight at all times). Or it could be some other issue such as the voltage supply to the receiver dropped too low and cause reception to be lost (though low voltage should have been logged).

Can you post the log data?

Hi Steve, wow all this clever stuff with my Jeti recently! I'm in contact with their support people and they want screen-shots so I had to find out how to set that up and send them what they wanted, phew!

Attached is the flight log, hope it's what you expected, if not maybe you can help me to zero in on something else. I also looked at the data logging and that needs me to spend more time with it. I discovered that vibrations aren't a problem as the highest peak was only 8%, sounds good to me!

View attachment spirit-log-2016-08-16-120401.pdf

Bye now!

 

[Smoggie]

Interesting Phil!. Something bad happened at the end of the flight that's for sure and it must explain the crash.

So the reported error is "Receiver Signal Lost"

Bearing in mind that this is the log from the Spirit and not the receiver itself this can only mean that the Spirit was no longer receiving a signal from the receiver. This is different to the receiver itself not receiving an RF signal from the transmitter. If the receiver lost it's RF connection then it would go into 'fail safe' which (depending on setup of receiver) would either fix the servos in last commanded position, or it would move them to a pre-set 'failsafe' position. Either way the Spirit would continue to receive a signal from the receiver even if the receiver itself had lost its RF connection with the transmitter.

For this reason I think this is most likely a different type of error. I think it probably indicates that the receiver shut down completely or that the wired connection between the receiver and the Spirit was broken (loose connection maybe?). A fault in the connection between the two is only likely if you were using a single wire connection, the failure of several different wires at the same instant is highly unlikely.

So if you were using a single wire hookup between Rx and Spirit I'd be looking very closely at the security of the connections at both ends, maybe power it up and give the wire and connections a bit of a 'tug' and see if connection is lost.

PS.....I'm guessing that the 'low voltage' error at the very end is where you disconnected the battery, so probably no concern.

 

[Heliman450]

Hi Steve, thanks for the feedback.

I'm intending to go see my Jeti/Spirit Pro supplier to get his advice on what's available to provide a second receiver unit. I don't think it will be the same as the 7 channel one, which I currently have as I don't need that many channels. I'll also speak to him about this error message and probably buy another Ex-Bus link cable as a precaution and anything else that he thinks will assist in the solution.

My intention was to do all the things with my Jeti Tx. that I put to one side in my quest for more stick time. Hopefully it will all come together soon and not last too long.

Cheers and bye for now!

 

[Smoggie]

I'm sure that your receiver will have dual diversity antenna (so it's actually already effectively two receivers in one box). There should be no requirements for another physically seperate receiver. I doubt if it's even possible to fit one, though I'm no Jeti expert so i could be wrong on that point.

Interesting to hear what the Jeti support guy says.

 

[trainrider06]

Hi Steve, wow all this clever stuff with my Jeti recently! I'm in contact with their support people and they want screen-shots so I had to find out how to set that up and send them what they wanted, phew!

Attached is the flight log, hope it's what you expected, if not maybe you can help me to zero in on something else. I also looked at the data logging and that needs me to spend more time with it. I discovered that vibrations aren't a problem as the highest peak was only 8%, sounds good to me!

View attachment 16391

Bye now!

I just checked the log out that you posted, I am beginning to suspect something went wrong and not of your accord there Phil, seems you had a massive power failure somewhere. Phil did you run the servo test in the spirit program?? The one where it really puts the servo's through the ringer, and they go up and down really fast? Are you running an auxiliary pack for the servos??

 

[Heliman450]

Hi Rodney/Steve, the massive power failure occurred as the heli hit the ground when the battery launched itself forward taking the canopy with it

Since changing my ESC and having two power supplies coming from the main battery I'm showing a good 6.0V at the receiver against my previous 5.7V using a separate battery for the Spirit Pro/servos as it was with its original set-up. The receiver power supply went back from the Spirit Pro to the receiver along the Ex-Bus cable, which Steve is advising should be checked out, I'm just going to change it out anyway. No cables had come out but there could easily be a bad connection in there.

I haven't felt the need to do the test on the ESC as it was an upgrade from the standard 70Amp to a new, 100Amp unit. Of course, since the feedback here, I intend to rebuild and adopt whatever is necessary to give me some confidence that the signal loss from the receiver to the Spirit Pro doesn't occur again (no 100% guarantees in this world!).

Since the crash, I've spent a lot of time running the replay through my mind and it seems more likely to be Steve's explanation. At the moment I thought "Oh dear, this is going to be expensive" the heli was facing left side to me about 60m to my right and maybe 30m altitude putting the two antennae on the heli away from me. I intend to find a satellite arrangement to prevent this in future although I haven't looked at Jeti's website yet.

I think this covers the points you both raised, thanks for the feedback.

 

[Smoggie]

If there is even a slightest chance that it could have been a reception issue then make sure to conduct a thorough range check on the heli before flying again, including range check from different orientations. Some transmitters these days give 'RSSI' (Received Signal Strength Indication) which is sent to Tx from the Rx by telemetry. I'm not sure if jeti has that feature?

If your Jeti does have it then you may be able to get a data log from the Tx which would show any reception issues.

 

[trainrider06]

This is why I use Spectrum stuff, I scratch my head enough over that, and one of those new fangled things like a Jetti would only smoke my pea brain to a crisp trying to reckon any issues with those systems.
But when you described how the heli went down, that would surely indicate something failed in the system itself. The only other thing would be a frozen finger of panic where one watches the heli pound it'self into the ground and then upon reflection you realize that your finger flew it into its demise. I believe you have already reflected that option out of the equation though....

 

[Heliman450]

Hi guys, thanks for keeping on my case.

Rodney, I've always liked a challenge, hence, taking up a hobby that I've had no experience of during my younger years

I know that my finger didn't freeze as the collective stick was at 100% when the heli hit the ground. I even had time to decide not bothering to try one of those fancy auto rotation thingeys as nothing was responding to my controls anyway. I'm only surprised at how little is actually broken but it didn't just plunge into the deck, it was quite graceful actually. The Olympic judges might have even given it a good score.

Steve, when I finally get around to changing out all the stuff I want and the 'new' DFC head arrives, I'll enlist my good lady's services as a remote witness to whether a problem still exists before flying. At the end of the day, I must take the chance of flying it as I don't want to just look at it all nice and shiny sitting on the shelf. Fingers crossed!

Thanks again and bye!

 

[Smoggie]

The box of goodies was shipped today Phil. Royal Mail say three day delivery.

I wonder if the Spirit's 'auto-level' stabilisation helped keep the heli upright as it descended, even after communication with the receiver was lost? I think it should have.

 

[Heliman450]

The box of goodies was shipped today Phil. Royal Mail say three day delivery.

I wonder if the Spirit's 'auto-level' stabilisation helped keep the heli upright as it descended, even after communication with the receiver was lost? I think it should have.

Excellent! Feels like Xmas all over again

I'm sure that the Spirit Pro helped a bit to keep the crash from being a total disaster as it came down so upright. I'd just completed a right turn and was slowly increasing the collective to prevent it from losing height and it just kept on going as though something had locked and the increased pitch didn't give any lift.

It's to one side at the moment as I work on the very damaged Blade 450. It's almost together. Just the head rebuild and set-up to do. Normal life family things are getting in the way at the moment