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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: Sennybridge jamming trial
22/08/2019 11:17:48

They don't mention the 868MHz band, I wonder if that is included?


Thread: Prop size and efficiency
19/08/2019 12:23:24

I'm curious as to what formula you used for the "Volume of air per rev (cubic inches)" value.

For a 7x5 prop you have 3023.35. I would expect the calculation to be 3.5 * 3.5 * pi * 5 (as in pi * radius squared * pitch) for which I get 192.42.

You appear to have used (3.5 * pi * 5) squared!

My understanding is you need to consider the velocity of the air moved as well as the volume (mass) moved. The energy imparted to the moved air is kinetic energy, so is 0.5 * mass * ( velocity squared). This means a larger prop of the same pitch as a smaller prop, but rotating more slowly, will move a greater volume (mass) of air, but with less velocity. The energy imparted to the air may then be less.

Calculating this energy for the 7x5 and 10x5 props for the first motor in your list, I find the 10x5 is only about 16% "better" than the 7x5, as opposed to about 53% from your spreadsheet.

For electric power, there are electrical losses, and these are mainly due to the current flowing, and proportional to current squared. Moving to a lower voltage, and hence a higher current is likely to increase these losses, and the extra loss may be more than any gain from a larger prop. Personally, I try to use a higher voltage with a lower Kv motor to reduce the current while driving a larger prop.


Thread: X9D+ 2019 or Q X7S?
14/08/2019 20:53:48

Posted by Peter Christy on 14/08/2019 08:42:54:

I would expect QX7s to have Access in the near future as well. It may even be possible to do a firmware upgrade to the new protocol at some point, as I seem to recall reading somewhere that FrSky would offer this to hardware that was capable of supporting it.


My understanding is ACCESS will not be supported by a firmware upgrade as FrSky do not want to make the ACCESS firmware accessible by putting a logic analyser on the connections between the processor and the RF chip. The ACCESS hardware uses a single chip with both processor and RF on it so the signals are not accessible. FrSky even grind the identification off this chip (although I can make a guess what it is!).

Any upgrade to older radios is by replacing the RF module.

FrSky are also dropping support for the older 'D' receivers with ACCESS. This is partly because the 'D' protocol is not legal in the EU for new products. I'm in the middle of producing new firmware for D8 receivers that uses the 'X' protocol. I have something working (FCC version so far), that controls servos and sends some telemetry back for the two analog inputs and RSSI.


Thread: S6r Rx downloads
09/08/2019 17:35:11

The failure to write from V1.4 has been reported by others (on RCGroups).

I managed to install the Freelink tool, in spite of the installer being in Chinese, and this worked OK with the STK to a S8R.

Another alternative is to install the "SportSet" tool I have written. See this post for details: **LINK**, and post 8682 on the same thread gives more detail.


Thread: Registration of flying sites with NATS/ATC
04/08/2019 12:05:08

Not that being listed stops overflying by light aircraft. I fly at one of the listed sites and we had a full size fly over quite low last Friday. I could almost read the registration. I wasn't flying at that time, but I did have my Cularis at over 700 feet during a couple of flights, I reckon the light aircraft was lower than that!


Thread: Build your own telemetry sensors.
31/07/2019 12:45:35

Where did you get the Arduino IDE from?


Thread: Differential thrust mix.
26/07/2019 00:13:22

For electric, I'd recommend reducing one throttle with a rudder mix, never advancing a throttle, otherwise you could end with the situation a motor starts up when only rudder is applied.

I found I needed some differential throttle on my BH Mosquito for taxiing, otherwise it just would not turn.


Thread: Moon landing
20/07/2019 20:02:26

Why do you expect to see a "flame" from the rocket motor? Unlike the Saturn V first stage that uses kerosene, the lunar module uses hydrogen and oxygen, flames are mainly caused by glowing carbon.

For the landing, remember the rocket motor was not that powerful, it was only working against 1/6th of earth gravity. It is also mounted on the descent stage, so is a bit further away from the astronauts than you might think.

It appears that: "Apollo flight trajectories bypassed the inner belts completely, passing through the thinner areas of the outer belts"


Thread: Phil G's Frame Divider for S-Bus
16/07/2019 21:55:14

SBUS is still 9mS, and I don't expect it to change. Too many users feed it to a flight controller (e.g. betaflight), and want the 9mS rate to minimise latency.

My own SBUS decoder (on Github), using an Arduino Pro Mini, outputs 16 channels, at an 18mS rate. However, If I see a change on the SBUS 9ms after a pulse has been output, I send another pulse to minimise latency, but then revert to pulses every 18mS for a short while before allowing another pulse to be sent "early".


Thread: S8R stabilisation problemsanyone
12/07/2019 12:33:04

"latest" as a description of the firmware you have flashed is a bit vague! Do you mean the 20190531 version for the S8R?


11/07/2019 22:56:41

Is the Rx in "Quick mode"?


Thread: 9XD+
11/07/2019 22:43:38

The X9Lite runs both erskyTx and openTx. The internal module uses the new ACCESS protocol, but this now includes D16 mode. D8 mode is not legal in Europe for new radios as it doesn't conform to the the bandwidth use or LBT.


Thread: Number of channels?
11/07/2019 14:32:08

Both the X9D+ and the QX7 use an internal XJT module that fully supports 16 channels. For the receiver you either need 2 receivers, each providing 8 direct servo outputs, or you need to use the SBUS output that provides all 16 channels, for which you need either SBUS servos or a SBUS decoder. From a single receiver (e.g. X8R) you still get 8 servo outputs as well as the SBUS, so you may drive 8 servos directly, and only need the SBUS for the other 8.

If you have used an Arduino for anything, I have SBUS decoder code that runs on an Arduino Pro Mini and provides all 16 channels as servo outputs.

For the transmitter you also have the choice of erskyTx firmware as well as openTx. Many users find navigating around the menus, and setting up models, easier on erskyTx.


Thread: 9XD+
10/07/2019 19:28:59

The QX7 is about the same size as the X9D+.

There is also the X9Lite, which looks very like the X9D+, but is about 0.5 inches narrower. Only £66 from T9, although you will need a couple of 18650 batteries for it. It does have only one POT and 5 switches compared to the X9D+ 2 POTs, 2 sliders and 8 switches.

For firmware you also have the choice between erskyTx and openTx.


Thread: Understanding the numbers....
04/07/2019 16:50:01

I understand what A, B etc. should be (and are for a Spektrum Rx), I'm questioning whether the Orange implementation is actually reporting the same thing!

With 'B' reporting only 29 "Fades", it seems unlikely to me that there would be 732 actual frame losses. According to Andy Kunz of Spektrum, " A "fade" is when a single antenna does not hear a frame of data. ".


04/07/2019 11:38:57

I'm wondering if the Orange Rxs are reporting something different to Spektrum Rxs. You reported a 5-minute flight gave: A - 1429, B - 29, L - 0, R - 0, F - 732, H - 0

The 'A' value indicates one antenna missed 1429 frames while the 'B' value indicates the other antenna only missed 29 frames, yet there are 732 frame losses, which I understand is supposed to indicate 732 times where the two antennae received different frames. This may be one received a perfect frame and the other received a bad frame, however the perfect frame will have been used for control!


Thread: Switching Brand
20/06/2019 11:53:46

In my case I'm using FrSky S8R (stabilising) receivers. These use channel 9 for stabilising gain control, channels 10 and 11 to select mode (normal, stab. auto-level, knife edge and hover), and channel 12 for starting the self-check/ limit setting function. So that's 4 channels needed before any flying controls. Then, on my Mosquito, I have 2 ailerons, 2 throttles, flaps, retracts, elevator and rudder, so 12 in all!

Regarding FrSky transmitters, you may use erskyTx firmware as well as openTx, indeed, the recently released X9Lite is supplied with the choice between the two. erskyTx is generally easier to use, but not really any less powerful than openTx. They were both "forked" from er9x.


Thread: S6R receivers
15/06/2019 18:28:54

FrSky have posted new firmware for the S6R and S8R receivers.

This fixes the problem with only some RxNums working. It also fixes a problem where SPort data from the Tx didn't "pass through" the SxR.

I've just flashed a S8R (with the FCC version) and tested with RxNums from 0 to 10, all worked. This is with an early X9D+ twhere only some RxNums worked before.

I've also used my "ChangeId" script (on erskyTx), and changed the physical ID of a FAS sensor "over the air" using this S8R. This didn't work before either, or at least changing the voltage on a Neuron ESC didn't work.


Thread: Forum members' new models: Let's see them.
01/06/2019 21:45:10

Sort of new model. It flew many years ago with a HP61 up front. I've now electrified it, replaced the radio gear and all the linkages. It's basically a (Wolfgang Matt) Superstar although I built the fuselage a bit differently.

Wing span: 62 inches.
Weight: 6lb 13 oz.
Motor EMAX 3526-04, kv 860.
Battery 2 off, 4-cell 3000mAh in parallel.
ESC FrSky Neuron 60.

I tested it in may back garden and got around 65A, so I set the ESC to a current limit of 60A.

(re-)Maidened today, flew rock solid.


It flew quite happily on 20A, I only hit full power once, briefly after take off, showed 60.5A at 10900 RPM and 15.7V (so around 950W).
On the second flight the ESC temperature started at 38C and was 76C after 5 minutes and stayed there (don't you just love telemetry and logging?). THe second flight was around 6 minutes airborne and used 1700mAh of the available 6000.

I do have a FrSky S8R (stabilising) receiver in it, but it doesn't actually need it, it was completely stable even with some gusting winds.

I'm using this as practice flying a larger and heavier model ready to maiden my Warbirds Replicas Hurricane!


Edited By Mike Blandford on 01/06/2019 21:46:38

Thread: Need help to identify plants
01/06/2019 21:22:34

Leave the flowers to go to seed. Eventually you will get some brown "pods" that are full of seeds. You may then collect these and sow them where you want the plants next year.
Or sow them in a seed tray and get some plants ready to put where you want them (been there, done that!).


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