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Member postings for Martin Whybrow

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

Thread: Clearview - take care
31/12/2017 18:44:06

A lot of antivirus packages work on signature for executable files; if they're not in the database, or the signature doesn't match, the program is treated as malevolent and the AV deletes files; I have a recurring issue with one bit of software that my AV keeps deleting, despite it being 100% safe!

The issue with Kaspersky AV is that it's Russian and the US government has apparently detected that as well as sending suspicious files back home for analysis, it may also be detecting keywords in files and sending those home too (it's been suggested that words and phrases such as top secret or classified might trigger this behaviour).

Thread: Changing connectors on my Lipo batteries
22/12/2017 17:59:44

I consider the XTs to be one of the best battery connectors for the purpose and certainly don't consider them unsafe.

Thread: Ebay sellers...
19/12/2017 00:05:39

Possibly the most honest thing I've seen in a listing: "I don't know what I'm talking about with it"

Thread: rchobby-avenues.co.uk - London based
09/11/2017 19:09:06
Posted by Adrian Smith 1 on 28/10/2017 08:44:55:

Browsing the t'internet the other day, as you do, I came across this online supplier. **LINK**

If you Google their registered address, you may think twice about buying from them wink

Thread: Mystery Glider help!!!
25/10/2017 23:17:42

Send me a message with your email address and I'll send it to you.

25/10/2017 21:00:38

The wings look very much like the Greensleve wings; the Greensleeve has a conventional (low horizontal stabiliser) tailplane; the wingspan is 2m and is electric powered with a motor in the nose. The wings are 2 pieces, joined with a steel bar; the wings mount via 2 dowels at the front and 2 M6 nylon bolts at the rear.

The Cortina has the same fuselage, but has an all moving T tail, 3 part wings with no aeilerons and a span of 2.2m.

I have both plus two more unidentified models with the same fuselage! I also have the instructions for the Greensleve.

Edited By Martin Whybrow on 25/10/2017 21:01:21

Thread: Plod Vs Drone
13/10/2017 22:29:24

Glad that Essex police know the law, their neighbouring force, to the north and west, doesn't appear to have a clue from my experience with them.

Thread: Fire Extinguisher Disposal
05/10/2017 17:51:04

Pete, do you mean BCF or powder? BCF is a halon, so disposal is very different.

The powder is relatively harmless as it's either ammonium phosphate, which is a fertiliser, or potassium or sodium bicarbonate. If it's the type with a gauge, it's a stored pressure extinguisher so needs to be fired to make it safe; if there's no gauge, it will be a cartridge type which can be opened easily (the head assembly screws off), these usually have a wider neck and will have no sign of a gas fill valve. With the cartridge type, you could tip out the powder into the bin, reassemble the extinguisher and fire it in safety.

Halon is a very tricky substance to deal with owing to ozone depleting chemical regulations.

Alternatively, let the local fire brigade set it off for you!

Thread: Air France A-380
02/10/2017 23:01:29
Posted by Paul Marsh on 01/10/2017 20:32:09:

It's not the Rolls-Royce Trent engine this time, but a General Electric/Pratt and Whitney engine,but same non-contained failure as the Qantas Flight 32.

Edited By Paul Marsh on 01/10/2017 20:36:05

QF32 suffered a turbine disc failure on the Trent 900, this was a fan / shaft failure; agree that both were uncontained failures though.

Thread: Sad day for Bishop Aviations Red Arrows.
27/09/2017 18:28:50

The engine sounded very much like it lost one cylinder, was the object that came flying out a spark plug?

Thread: Caption competition!
19/09/2017 18:54:02

You're right, that boot IS much bigger than it looks from the outside!

Thread: What's flying over your house
18/09/2017 18:49:40

Not so much from my house, although it would have been very close, but was out gliding today from Cambridge Gliding Club (1st time I've tried gliding), I spotted a fighter aircraft ahead which then turned and passed directly over us a few hundred feet above us, we got a very close up view of a Sea Fury, fantastic!

Thread: lengthening ESC wires to battery
17/09/2017 01:39:56
Posted by Geoff Sleath on 17/09/2017 00:33:23:You're absolutely right, Martin except capacitors don't store voltage, they store energy and the energy (Q) in joules = voltage x capacitance (in Farads!). Obviously you can juggle the formula around to give the voltage.

Geoff

I'm going to be a real pedant here! Capacitors don't store energy, they store charge, Q is a measure of charge, not energy and it's measured in Coulombs.

17/09/2017 01:36:02
Posted by Denis Watkins on 16/09/2017 23:20:12:

Its voltage too guys, as a cap never runs at 100% capacity,

They discharge at a very high rate at 2/3rds the voltage.

So the 50v caps I see in the pics will discharge at 30v, hmmm ?

Choosing a cap is like choosing an ESC, in that we choose one near and above our operating voltage.

Caps come in various guises, and ours would be the 8v or 16v

And would do their work between 6 and 10 volts.

On reaching their case claimed voltage range, they immediately discharge and are ready again to fill.

This is how they smooth circuits

I'm not sure where you go this information Denis, but it's far from correct.

The voltage rating of a cap is the maximum voltage it's guaranteed to withstand before the dielectric breaks down; when selecting a cap, choose one that exceeds the maximum working voltage, e.g. for a 3S pack, use a 16V or higher rated cap. You could use a 250V rated capacitor, it would work but it would be much larger than the 16V cap and would cost a lot more as well.

17/09/2017 01:29:25
Posted by Geoff Sleath on 16/09/2017 22:28:13:

The only problem is that the capacitors you're adding look like aluminium electrolytic which can have quite a high inductance themselves if the aluminium plates are wound round the electrolyte as they often are. That means their ability to absorb high frequency spikes is limited. A better type of electrolytic is a solid tantalum, which is more expensive, but they have much lower inductance

Tantalum caps are very unreliable and best avoided where possible as they have a tendency to go short circuit. Much better is to look at the ESR and select an electrolytic cap with a low ESR value.

Thread: Had my first full size flying lesson!
17/09/2017 01:19:46

Had my first hands-on in a Cessna 182 about 25 years ago, then a Piper PA28 about 4 years ago; also had an hour in a 737-800 simulator a couple of years ago, a very worthwhile experience if you get the chance (if you're anywhere near Cambridge and fancy a try, I can put you in contact with the operator of the sim). On Monday, I have an entire day of glider training at Cambridge Gliding Centre, courtesy of my brother (my 50th birthday gift from him, he knows me well!)

Thread: Multiple servo quick connector
14/09/2017 01:51:57

How about a D connector, they're pretty substantial but reasonably compact.

Thread: TJD Models - a lacklustre performance
01/09/2017 00:14:15

Obviously those recommending Appliances Online haven't had to deal with them when trying to get something repaired!

Thread: BBMF (at least) Merlin powered planes grounded
31/08/2017 18:36:13

A colleague who's in the know mentioned it was picked up during an examination of the magnetic plug in the oil system.

It's a shame thay didn't find it earlier, the Lanc was supposed to do a display at our loacl show at Little Gransden last Sunday!

Thread: What's flying over your house
28/08/2017 01:54:35

Sally B was flying today (Sunday), she did her routine at Little Gransden show (Cambs)

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