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Member postings for Steve J

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

Thread: How did that happen
25/11/2020 21:15:53
Posted by iflylilplanes on 19/11/2020 23:37:13:

... had a club member carted off to hospital for 57 stitches when the TX was turned off first, electric model chewed his fingers for arms and stomach. ...

Sounds like your club member did not have his failsafe set correctly. If that is the case, he is probably lucky that he injured himself and not a third party.

25/11/2020 21:09:32
Posted by GrumpyGnome on 23/11/2020 07:57:12:

As it adds no effort to use Tx on Rx on Rx off Tx off and it MAY reduce risk, why not get into the habit ?

Because nobody has come up with an argument as to why, with the equipment that I use, transmitter on first is safer than model on first.

Thread: New Spektrum NX range
25/11/2020 16:56:16
Posted by Trevor Crook on 25/11/2020 16:30:00:

At present, the price of an NX8 is $20 more than a DX8. Als Hobbies list it at £60 more.

Indeed. The UK shops seem to be putting a significant premium on the NX transmitters that is not there on HH's US site. An early adopter and their money are easily separated .

25/11/2020 14:58:39
Posted by J D 8 on 25/11/2020 13:29:36:

I was flying on the weekend using a Spectrum NX [ not sure if 6 or 8 ] ...

Setting up and testing his new Wot 4 was easy, much the same as as older Spectrums.

Good to hear. It looks like incremental upgrade to the DX series. It will be interesting to see where the prices stabilise. It looks like my answer to "What would I do if my DX9 died?" which I ask myself every now and again has become "Get an NX8".

<off_topic>

IMHO anybody who moves to a certain German manufacturer at the moment is 'brave'.

</off_topic>

Thread: How did that happen
22/11/2020 22:11:20

Posted by Peter Jenkins on 22/11/2020 20:26:51:

Try explaining your ratiknale to the insurance company's lawyer in the event of an accident!

In that unlikely event, I would quote from the instructions supplied by the manufacturer of my radio equipment.

Q. After I've bound the receiver to my transmitter, which do I turn on first when I want to fly?

A. Either one.

22/11/2020 21:59:31
Posted by Peter Jenkins on 22/11/2020 20:26:51:

You shouldn't assume I know nothing about safety crtical software!

I didn't assume anything. As you are so knowledgeable, you should have no problem answering the following:

Case (1) A transmitter sends a signal equivalent to 0% throttle to a receiver. The receiver translates this to a pulse width and transmits it to an ESC which decides that it is 0% and doesn't spin the motor.

Case (2) A receiver powers up. There is no signal from the transmitter that it is bound to. It either sends no signal to the ESC or sends the signal that it was previously programmed to send in the absence of a signal from the transmitter, i.e. 0%. The ESC doesn't spin the motor. If there is no signal, the ESC doesn't even arm.

Please explain why (1) is safer than (2) assuming that the failsafe was set correctly.

Please explain why (2) requires SIL rated software.

Note that (2) is what 2.4GHz receivers do prior to acquiring the signal from the transmitter to which they are bound.

Thread: JR XG7
22/11/2020 18:33:45
Posted by David Chapman 5 on 22/11/2020 16:33:47:

trying to set up a throttle safety dis-arm using the Aux 2 switch.

If memory serves (and it has been a while since I've programmed a basic JR) you do something like mix thro to thro with an offset of -170 and a value of -100%. If your radio has throttle curves, it is easier to use them.

Thread: Drone Accident
21/11/2020 19:50:19
Posted by Ady Hayward on 21/11/2020 18:15:55:

I seem to recall a rather costly space probe crashed during its landing phase due to a similar Feet/ metres conversion issue.

Mars Climate Orbiter failed to enter Mars orbit back in '99 due a metric/imperial units mix up.

Edited By Steve J on 21/11/2020 19:51:46

Thread: Spektrum NX6 Rx Voltage
21/11/2020 14:32:08
Posted by Chris King 3 on 21/11/2020 14:07:14:

I thought (perhaps ignorantly) that the Rx would return the LiPo voltage through the ESC.

Only if the ESC is one of Spektrum's Smart ESCs and the AR410 supports Spektrum's SRXL2 protocol.

Thread: Drone Accident
21/11/2020 12:58:21

Nice try by the LAPD, but, IMHO, the RCMP still have the best drone/helicopter collision.

Thread: How did that happen
21/11/2020 06:20:25
Posted by Peter Jenkins on 21/11/2020 00:05:29:

Posted by Steve J on 20/11/2020 17:09:51:

If you have a decent radio and take a bit of time to understand how to use it and setup your models correctly (both of which the OP appears not to have done) then it shouldn't matter if you power up the model before turning on the transmitter and turn off the transmitter before powering down the model. In fact, there is a pretty good case for saying that it is safer to do so.

Only if you believe that the software in the ESC is built to safety critical standards.

As it happens, I know a thing or two about control and safety systems.

What would you say the approximate probabilities of the of the following are:

  • A brushless ESC deciding to spin a motor in the absence of a signal commanding it to do so.
  • A receiver deciding to send a signal to an ESC telling in to spin a motor in the absence of a signal telling it to do so.
  • Maloperation of transmitter leading to a signal being set to the receiver telling it to spin the motor.

In my experience, maloperation of the transmitter is dominant, so having the transmitter off while you have your squishy bits near the prop is probably safer than having it on.

20/11/2020 17:09:51
Posted by Allan Bennett on 19/11/2020 20:18:08:

Even if your failsafe is set for zero throttle, you should always disconnect the model's battery before turning off the transmitter.

Why? If you have a decent radio and take a bit of time to understand how to use it and setup your models correctly (both of which the OP appears not to have done) then it shouldn't matter if you power up the model before turning on the transmitter and turn off the transmitter before powering down the model. In fact, there is a pretty good case for saying that it is safer to do so.

Thread: BMFA kick backs/discounts for clubs
17/11/2020 07:12:43

Society of Model Aircraft Engineers

16/11/2020 14:28:20

Posted by MattyB on 16/11/2020 11:27:25:

Personally I would like to see the BMFA adjusting to this reality and looking to cut costs aggressively in the next 2 years. This would help to offset the loss in members and enable the BMFA to push forward a more aggressive programme to replace lost members from the (seemingly quite large) group who have registered with the CAA but are not current members of national associations.

IMO one of problems that the BMFA have is that if you aren't a member of an affiliated club and only want insurance the BMFA cost almost twice as much as one of the other associations.

16/11/2020 11:34:32
Posted by Dickw on 16/11/2020 10:42:57:

The latest news from the AGM is here.

That is just the fees. Anybody know if anything interesting was said that isn't in the documents published before the AGM?

Thread: DLE 30 Pitts exhaust
16/11/2020 07:49:14

IAD lists a JMB Brecka Pitts for a DLE-30.

I assume that you are aware that a Pitts will only get you down to the mid 80's dBm.

KS have an in-cowl muffler for a DLE-30.

Edited By Steve J on 16/11/2020 07:52:16

Thread: Can I use NiCad trickle chargers on NiMH?
11/11/2020 08:16:42
Posted by Neil James on 10/11/2020 13:55:57:

... can I use these chargers designed for NiCads to charge and maintain NiMH, given the differences in voltage and chemistry? ...

Can you? Yes so long as the current is below the continuous overcharge rate given on the datasheet. Should you? No. You should be delta peaking and you should be cycling conventional NiMHs every 3-4 months.

Thread: The Gov't, CAA, BMFA & UAV legislation thread
06/11/2020 18:42:46
Posted by Cuban8 on 06/11/2020 09:15:52:
Posted by Martin Harris on 06/11/2020 00:23:07:

Yes, I have a few concerns over future changes but I'm pretty confident that the BMFA et al are busy negotiating to mitigate many of their effects.

Exactly - a storm in a teacup if ever their was one.

The CAA published the 8th edition of CAP 722 yesterday. Here is page 186:

cap722 page 186.jpg

UAVs flown in the specific category are required to have electronic IDs from next December.

Thread: A disengaged membership?
02/11/2020 16:19:42

Posted by Mike T on 02/11/2020 14:37:35:

Official bodies tend to like persons and organisations that bring them solutions to problems and I believe the senior echelons of the BMFA are seen in that light.

Would that be the same BMFA that the DfT/CAA gave up talking to early last year and who only got back in the room when a more sympathetic person became Secretary of State and told the CAA to talk to them?

Thread: Flying through covid !
02/11/2020 07:00:54
Posted by Doctor Chinnery on 02/11/2020 01:00:08:

As someone just said: it's only a month,

ROTFLMAO

and the weather isn't very tempting anyway.

Where I live there is a decent forecast for the second half of this week.

they are trying to contain a potentially fatal disease

I truly don't know what the government's strategy is. It seems to be do what the polls say and hope that something turns up.

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