Official Freewing T-33 Shooting Star 80mm EDF Thread

[F22trainer]

This video has a lot mixed in it, including some forgotten fun before an incident with my T-33, along with helping folks fly a Hobbyzone Carbon Cub S.

For the record, I love this jet and tell everyone they should get one :D

Mine will be looking like that one soon. If I had not already purchased a wing as part of another project with a design for the round wingtip option, it would be spare parts for someone. But new fuselage is on the way. The twelve blade fan is a nice upgrade.

[GBLynden]

This video has a lot mixed in it, including some forgotten fun before an incident with my T-33, along with helping folks fly a Hobbyzone Carbon Cub S.

For the record, I love this jet and tell everyone they should get one :D

[GBLynden]

In case you didn’t hear, she went down last weekend
Crew OK.

I am sorry for your loss!

[F22trainer]

In case you didn’t hear, she went down last weekend
Crew OK.

[Evan D]

Thanks OV-10!

[OV10]

Don't know why/how/who did it, but have corrected it.

[Evan D]

Why did this move from the regular spot?

[HangarQueen]

The only thing that remains suspect to me would be the ESC/BEC unit. I don't know how to test these units on the bench and since I don't run telemetry receivers I'm not well-versed enough on how to detect any sort of irregular operation.

It sure looks that way.
The way that I can think of to test this on the bench, is to put a decent load on the battery and monitor the voltage. My charger has the means to measure internal resistance of the battery, which is an important parameter that could cause a serious voltage drop under heavy load.
But then again, as I write this, I realize that this could not cause the BEC output voltage to drop; the battery voltage would have to drop extremely low for this to happen.
Remains the BEC itself. How many Amps is it rated? Try to put a serious load on it and monitor the voltage.
Another thing: how close is the ESC to your receiver? An ESC switches at pretty high frequencies, and can cause interference for your receiver.
Too bad you don't have telemetry, because that is really a great tool in circumstances like this, you can zoom in on the shortest of voltage drops.
I use Frsky equipment, and it logs these parameters 5 times a second. And the best part about telemetry is that it constantly monitors signal strength and quality at the receiver, and reports back. Whenever the signal becomes too weak, the radio will give an aural warning, long before you effectively lose connection. I've had that warning a couple of times, because of bad antenna placement. Without telemetry, something far worse could have happened.
In the case of the crash in my club, we were first thinking towards the capacitors because he was using a (new) stabilized receiver (Spektrum), and that leaves the possibility that the stabilization could have caused some spikes in the power supply, which could be solved with capacitors.
He added the capacitors after the first event of loss of control and all went well for a couple of flights. But then the loss of control occurred again, resulting in a total loss of the airframe.
It is really frightening when that happens, because there is no clear explanation.
One thing is that he appeared to have some form of interference in one particular corner of our airspace, with different models (and thus different receivers). As I said, he is a serious and experienced RC pilot, he wouldn't lie about this at all. I have never experienced this sort of problems with any model, so there might be a source of interference that his radio seems to be vulnerable to (there is a house in that corner...), we can't exclude that. And no, I'm not trying to bash Spektrum brand in any way, we have just been trying to analyze a problem in an objective way.

[Gilatrout]

I lost a plane today due to signal loss. Given the orientation, the battery probably blocked the signal. Anyway, the way failsafe was set, the plane just spiraled in.

I'm not familiar with futaba, but spectrum indicates signal loss as a hold in the transmitter. Once a hold occurs, the receiver goes into failsafe unless it reacquires the connection.

Much of what you are describing sounds very similar to loss of signal/failsafe.

[RobWetterholtJr]

HangarQueen,

Thanks for the response.

I know the BlueBoxes have come under scrutiny in different FreeWing aircraft threads and so I decided to bypass it in both my T-33s. I've read numerous reports of people having no problems either way.

Of particular interest is the fact that the BlueBoxes don't seem to serve to reduce voltage (the voltage reduction down to 5.5 Volts occurs in the ESC/BEC unit) but instead acts as a sort of fancy Y-harness so these models can be flown on a six-channel radio, if desired. With that in mind I decided to go straight in to the receiver and not risk faulty trace lines...and in more than 20 years of flying I've never done anything but wire everything directly in to the receiver, with no problems.

I'm confident the servos, receiver, transmitter and battery were not the cause here. The transmitter was declared fully functional by Futaba. The battery, receiver and servos were brand-spankin' new. In post-crash analysis on the batteries I haven't been able to produce any sort of cell imbalance after putting them through charge/discharge cycles.

Color me STUMPED!

The only thing that remains suspect to me would be the ESC/BEC unit. I don't know how to test these units on the bench and since I don't run telemetry receivers I'm not well-versed enough on how to detect any sort of irregular operation.

[HangarQueen]

I can really understand your frustration, Rob. I would be extremely bummed too.
We had a similar incident with this same model in our club last year. The guy lost control over his T33 and it went in, badly, irreparable. He is a good and very experienced pilot, wouldn't lie about this. When he screws up, he owns up to his mistakes. But he felt sick about this one, because he felt like there was nothing that he could do to prevent this.
I'm not sure, but I think he didn't bypass the Blue Box. And if I remember well, he had these short bouts of loss of control during the first flights too, which freaked him out. He installed some capacitors on the power supply to his receiver, that I remember, because they recommended this for that type of receiver. But it clearly didn't solve the problem.
I own the L39, bought it from another club member after he crashed it. He was convinced that he stalled it, but I saw it happen and it sure wasn't a stall. During a (fast) low pass, it suddenly rolled to the right and went in. He wanted to throw it away, so I offered to buy it from him for a very reasonable price, and I repaired it.
As I have more than enough channels on my radio, and I leave the model assembled all the time, I decided to bypass the Blue Box for everything except the lights. I never experienced the slightest glitch on that model. And it flies like a dream 😊

[RobWetterholtJr]

xviper,

If my frustration wasn't readily apparent from the get-go I don't know what to tell you. Furthermore, your lecture about how me only wanting to hear what conformed to my ideas was akin to rubbing salt in an open wound, I did not appreciate that.

I provided what info I thought would be relevant and provided info after reading your response in hopes that that would hopefully shed light on what's going on...only to get another response about how releasing bits and pieces of info can only lead to more guessing.

I guess if that's where we're at here with problem-solving the gremlins that run around in these EDFs from time to time then stepping away from this segment of the hobby might be the right thing for me to do.

I am still bummed.

[xviper]

xviper,

Before you throw any more shade my way about whatever box you think I'm trying to put these crashes in, I'll let you know I removed the blue box in both of my T-33s and routed everything to the receiver directly as follows:

Channel 1: Ailerons (both servos Y-harnessed)
Channel 2: Elevator servo #1
Channel 3: Throttle
Channel 4: Rudder
Channel 5: Flaps (both servos Y-harnessed)
Channel 6: Gear (all three retracts triple-harnessed)
Channel 7: Nose gear Steering servo
Channel 8: Elevator servo #2

So where do we go from here?

As far as your comment about "did I even test them afterward"...yes. Everything checked out 4.0 on deck post crash.

I did notice a weaker than normal left aileron servo in my second A-4 post-crash during a bench test and so in both T-33s I used brand-new HiTec HS-65HBs. All servos exhibitied normal characteristics post-crash.

Perhaps this bit of information would have been useful in helping diagnose your problem? Both being that you already removed the blue box AND did the after test?
As for throwing "more shade" your way, remember that it was you, who clearly stated that you did NOT want to hear any "schtick". You threw the first "shade" and set the tone for what kind of answers you wanted.
When you hooked it up using 8 channels in a 6 channel model, (not saying there's anything wrong with this but ............... ) you could have easily introduced a level of complexity that making after crash diagnostics requires investigating additions points of failure. So, where do you go from here? Well, I'm not fully in tune with little bits of information that get added piece by piece after the initial enquiry. Your first post had a tone of anger and "stand offishness" and your last reply has a tone of "Don't be obsurd, I already did that", so I'm bowing out. Even though my first instinct was to stay out of this, I tried. I'll let others provide more guesses as you release more information. You already know what you don't want to hear. I'm not willing to continue guessing at what you might want to hear.

[RobWetterholtJr]

xviper,

Before you throw any more shade my way about whatever box you think I'm trying to put these crashes in, I'll let you know I removed the blue box in both of my T-33s and routed everything to the receiver directly as follows:

Channel 1: Ailerons (both servos Y-harnessed)
Channel 2: Elevator servo #1
Channel 3: Throttle
Channel 4: Rudder
Channel 5: Flaps (both servos Y-harnessed)
Channel 6: Gear (all three retracts triple-harnessed)
Channel 7: Nose gear Steering servo
Channel 8: Elevator servo #2

So where do we go from here?

As far as your comment about "did I even test them afterward"...yes. Everything checked out 4.0 on deck post crash.

I did notice a weaker than normal left aileron servo in my second A-4 post-crash during a bench test and so in both T-33s I used brand-new HiTec HS-65HBs. All servos exhibitied normal characteristics post-crash.

[xviper]

Earlier in this thread and all along the way in the thread, there's been talk about issues with the "blue boxes" (control boards) using ground paths that come from many different components. On some of the boxes, some ground paths (circuits) are very close to another ground paths and coupled with sloppy soldering, a ground for one component can jump to an adjacent circuit. Some people have had failures that can be presumed to be linked to this phenomenon. Those who are concerned about it have removed critical components such as AIL and ELE and even retracts from the blue box and wired them directly to the RX. It has been said that removing the retracts from the box may not be a good idea since powered components such as lights take their feed from the retracts.
I've had two of these T-33s. First one on maiden took off and immediately inverted and crashed. I fixed it and sold it. Second did the same thing but I was somewhat prepared for it so when it inverted, I cut all power and didn't touch any of the sticks and just let it come down (fairly gently on its back). Fixed the minor damage and removed the AIL and ELE from the box and hooked up directly to the RX. It has flown many, many times since without incident.
So in retrospect, no, I doubt very much yours had anything to with a faulty ESC or BEC. (Did you even check them afterwards to see if they still functioned properly?) It's more like they had poorly made blue boxes. Many owners of certain Freewing planes (jets in particular) immediately remove critical control surfaces from the blue boxes even before the first flight.
I refrained from responding when you made that statement about not wanting to hear any "schtick". At the time, that indicated to me that you only wanted to hear what might conform to your ideas of what should be wrong. However, in truth, these cross contaminating ground paths in the blue boxes are few (although significant) and the vast majority of owners have never had such problems, BUT THEN, you didn't want to hear that did you?

[RobWetterholtJr]

Same. I have the 64mm Lippisch and MiG-15 and can't kill the darn things!

My experience with these 80mm 6S size EDFs has been nothing but a disaster. I'm continuing to wonder what in the world is going wrong...

[MikeT]

Interesting. I've never had a issue with any of Freewing and Flightline stuff. Maybe I'm just lucky.

Mike

[RobWetterholtJr]

MikeT,

Exact same receivers in all four. All brand new. Both antennas routed externally. One vertically next to the canopy and the other horizontally (on opposite side of fuselage) at about the same height.

[MikeT]

Hey MikeT,

I was using a brand new Futaba R2008SB receiver. No telemetry.

Interesting, how about the other 3 aircraft you lost. Just curious.

Mike

[RobWetterholtJr]

Hey MikeT,

I was using a brand new Futaba R2008SB receiver. No telemetry.