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Member postings for Mike Blandford

Here is a list of all the postings Mike Blandford has made in our forums. Click on a thread name to jump to the thread.

Thread: Jumper T16
28/04/2019 21:52:21

Details here: **LINK**

Yes, with the diode, it does work in a Taranis.


28/04/2019 17:56:31

Try using a different "receiver number" on the Tx. I know, with the S6R/S8R there is a problem with some XJT modules with some "receiver numbers". I suspect it has to do with the module unique ID. Yo may have a similar problem with the 4-in-1 module.

If you are using an unmodified DJT module then the telemetry data is only available on the connector on the rear of the module.I have modified my DJT modules so the telemetry signal connects to the bottom pin of the module connector (via a resistor and with a diode clamp) so the telemetry is available directly.


28/04/2019 00:03:35

The "FrSkyX" LBT protocol in the 4-in-1 multiprotocol firmware doesn't actually do a listen, it just handles the correct data format. I'm not aware of any plans to fix this (and I coded the changes to support the LBT option).

On all the multiprotocol modules I have, I notice the power output when using the CC2500 chip (used by FrSky protocols) is noticeably lower than a "proper" FrSky module. Careful range checking is therefore recommended.

Personally, I only use real FrSky Tx modules for the FrSky protocols because of this.

Note that FrSky are also very unhappy with Jumper as Jumper appear to have basically copied the FrSky X7 (for the T12) and the X10 (for the T16), so taking advantage of all the development work done by FrSky without incurring the corresponding costs.

FrSky provide me with technical data on their radios (under a NDA), to enable me to port ersky9x firmware. I've been waiting over 5 weeks for similar data for the T16!


Thread: Build your own telemetry sensors.
23/04/2019 15:58:55

Just for information, the lower of those two boards matches the "official" Arduino Pro Mini, as seen on the Arduino site. I also note on the rduino site it indicates the Pro Mini has been "Retired"!


Thread: Understanding the numbers....
21/04/2019 01:27:18

Even with the model on the ground, the height of the aerial above the ground is important. The range you get could be significantly different if the aerial(s) are at the bottom of the fuselage or at the top. You could easily by looking at 4 inches or 6 inches, which would make a 50% difference to the range!


20/04/2019 21:46:46

A couple of things (if you are measuring accurately). 90 feet is 27.4 metres. Going 30 metres away is 10% further.
Secondly, and more significant, the range you get is proportional to the height of the receiver aerial above the ground. Depending on where on the model the aerials are, they could be very close to the ground, e.g., on a glider with no undercarriage they could be only 3 inches off the ground, on a power model with an undercarriage, they could be 6 inches above the ground. You would get a significant increase in range with this.

I always do my range checks with the model on top of my flight box, so the aerial height above the ground is about the same for all models, probably about 12 inches.

Also, in your back garden, you may be getting signal reflections that cause the range to be reduced.


Thread: Build your own telemetry sensors.
17/04/2019 19:32:20

Andy: When adding heatshrink, make sure you don't block the holes in the pressure sensor.

If you just want to sense analog voltages, I have a simple project here (uses 3.3V, 8MHZ Arduino): **LINK**.

Looks like I built my vario sensor back in December 2015, after I had written the code for the SPort interface and the millis()/micros() that work without using interrupts so the software serial timing works reliably.


Thread: Sticky throttle
14/04/2019 23:01:03

As I now understand it the switch warning doesn't handle this requirement. There are TWO correct positions for this switch and one incorrect one in this application. The switch warning currently only handles ONE correct position and two incorrect ones.

It looks to me that the switch warning would need to be enhanced to support this.


14/04/2019 15:40:51

Totally confused now!

If the "Switch warning" is set to require SA to be UP, then surely you get a warning if it is NOT UP, which seems to be what you require!


Thread: Who wants a Warbird Replics Hurricane?
09/04/2019 18:50:15

I've just weighed my Hurricane (without flight pack) and it comes out at 6 lb 8.2 oz. The 6S, 3000 battery is around 18 to 19 oz, so I'm looking at 7 lb 11 oz plus any extra nose weight I need!


06/04/2019 20:53:57

Getting close to finished! I've still to fit the pilot and canopy, but the radio and electrics are all in. Just fitted a FrSky MLVSS (specially wired to give pack voltage only), and an FrSky RPM sensor. I already had a FrSky 150A current sensor fitted. All are mounted in the cowling area, as is the ESC. If I need some nose weight, it may as well be useful!

I think I shall go with a 12x6 prop, just got a couple of Master ones and a 3" black spinner. All fitted and working. I did a quick test indoors using s 2S, 3000mAh battery. I had readings of 7.2V, 9.0A and 4450 RPM. I haven't checked the calibration of the voltage reading yet. As I intend to use 6S, I could be looking at 12000 RPM on the 12x6 and around 1000W.

The next job is to check the CofG. Given I've used the larger tailplane size, I'm wondering how far back from the position on the plan, (mentioned earlier in this thread as conservative, nose heavy) I could go. I like "light" for the overall weight! I'll probably put the 6S in and check the weight and starting CofG position.

For information, someone on another forum asked about the MLVSS sensor (normally plugs into the pack balance connector and reads all the cell voltages) and if it would work to just measure the whole pack voltage, wired to the ESC power leads only. I did some tests and came up with wiring 6, 2K7 or 3K3 resistors, one each between the seven connections to the MLVSS. This provides suitable input voltages to each one, and then gives the total pack voltage.

I'll need some stick time on other models before I fly this!


Thread: How to use IRX4+ multi-protocol module with Taranis?
30/03/2019 16:45:07

For information, the Multiprotocol code was updated at some point to do channel mapping and scaling.

This means, for example, you have a default channel order used in the radio (e.g. AETR), with the mixes set to 100%, and the module maps this to the selected protocol. So if you use "DSM" the module takes in AETR at 100% and sends TAER at 80%.

When the firmware is compiled for the module, you specify the input channel order you wish to use. With a purchased module like the IRX4+, this is whatever they have decided to load!


28/03/2019 18:45:08

You might try asking here: **LINK**.

The firmware on the module is the same as in that thread, the hardware is just a copy really.


27/03/2019 23:08:12

I don't use openTx, but I understand if a protocol isn't listed by name, you may still select it by number.

Each protocol has up to 8 sub-protocols. For Bayang, there are 4, sub-protocols implemented:

0 Bayang
1 H8S3D
2 X16_AH
4 - 7 are currently not in use


Thread: FrSky ACCESS - New improved protocol
25/03/2019 18:47:43

No timescales at present, FrSky are working on the firmware for the modules and receivers. They will provide this when ready so the open source changes may be tested.


25/03/2019 18:42:57

There is quite a bit of work involved in supporting this new protocol, it is actively being developed and implemented. It should be available on all FrSky transmitters and supported by ersky9x and openTx.

My view is it will appear at much the same time on all transmitter firmware.

The details of the protocol between the radio and the Tx module are being refined as the firmware is developed. This is happening in the same way that the Taranis was developed with direct involvement between FrSky and open source developers.


Edited By Mike Blandford on 25/03/2019 18:45:42

Thread: Who wants a Warbird Replics Hurricane?
24/03/2019 16:25:02

Interesting, I wonder what the mechanical explanation is! Normally, I would expect the motor to speed up as the 'plane gathers speed. Since I'm looking to use 6S, my motor should be rotating quite a bit faster than yours already!

The prop washer on mine is already hatched.

I'll check to what I have the timing set anyway.


23/03/2019 22:49:14

I did some power tests today. The motor I'm using is an E-max GT 4020/07, KV=620. My plan is to use 6 cells, although at that KV value, 5 may be better to give a larger prop.
Test 1 with a 11x7 master prop gave took 36.5A, so around 800W.
Test 2 with a 13x6.5 APC-E prop took 52A and around 1100W.
Test 3 with a 12x6 Graupner grey prop took 45A and around 950W.

I hadn't got an RPM sensor hooked up, but I'd estimate test 1 at around 11000RPM. As I was using a 4-cell and a 2-cell in series (3000mAh), I didn't have a full voltage reading either, although the 4-cell (quite old) showed between 14.6 and 14 V.

I'm tempted with the 11x7 and 800W at the moment, although a 12x6 may look better.


Thread: C rating on Lipo's
23/03/2019 22:27:54
Posted by J Moyler on 23/03/2019 15:57:24:. . .. In the example above this means 60% of 44Amph = 24.4 Amph. .

60% of 44Amps is 26.4Ampswink


Thread: Does your club prohibit the use of after-market receivers?
23/03/2019 21:35:16

I would question whether this actually achieves the objective. I would assume the club would allow the use of an Orange Tx module with an Orange receiver. However, some of the Orange modules had a fault in their firmware, I found the fault and reported it to the firmware writer. For the Orange modules I have, I re-flashed them with the multiprotocol firmware that had the fault fixed. So, as far as it looks, I would be using an Orange module and receiver!

As it happens, I normally only use FrSky, but I have used other modules and receivers when testing them.

Another possibility could be someone has several DSM2 receivers which match the make of the Tx, but some DSMX receivers that don't. I would suggest the DSMX receivers may well perform better, particularly on a crowded flight line.

I would also wonder what that club thinks of open source Tx firmware. Personally, I'm much happier using that as I know what is in it!


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