Here is a list of all the postings Guvnor has made in our forums. Click on a thread name to jump to the thread.
|Thread: Weston Park 2019|
Went today (Sunday). Two gripes, stupid number of bodies standing around in front of the fence blocking the view, and secondly, by 1:00pm today, most of the pilots and their interesting models had departed, leaving us with endless 3D aerobatic displays.
|Thread: Exponential for beginners?|
",I have driven most means of transport available, from tanks to light aircraft, and there is one thing they have all had in common. Their controls were always linear. "
Some new cars have non linear FlyByWire steering.
Airbus airliners have non linear controls, as do most modern military aircraft...
"Lets hope someone had bought it and it will continue to produce."
I thought the machinery had been scrapped...?
|Thread: Balsacraft Blenheim replacement canopy.|
Call Sarik - they may have the moulds...
|Thread: BMFA SUBS|
But thats partly what it's for. Go and ask the CAA...
What worries me more than anything is the numbers of BMFA members who admit to binning the BMFA news as it comes through the door, evidently having failed to look for any urgent safety or technical notices. talk about reponsible flyers.
|Thread: RAF Scampton to be sold|
1) All of the buildings on Scampton are listed, so any developer will have to preserve them.
2) The A15 will have to be straightened back out by any buyer - it's in the covenants.
3) There isn't a bottomless pit of money to preserve every wartime airfield.
4) Scampton has been run down for years - Labour tried to close it 10 years ago...
He won't know as much as you'd think, seeing as he retired 20 years ago... The world has moved on...
|Thread: RAF's Finest Biplane? Hawker Fury MkI|
Anyone worked out the weight of an A4 sheet of 1mm brass...?? Would 0.5mm be more suitable?
They've gone into administration...
|Thread: New Drone Laws from 30/5/2018|
It's all kicking off on the drone Facebook groups...
The drone brigade all now think that if they join the BMFA they are exempt from the Dronecode 400 foot rule. How has the associations defined 'Model Aircraft' and 'Drone'...?!
The CAA WILL want transpoders eventually, and yes, we will pay for them.
They are here, now.
It's no longer on the BBC News website as other news has taken it's place.
How long would you like it left there? A week? A Month??
The BBC haven't 'dragged up old news', they've reported on a new piece of legislation heading for Parliment.
How hard is that to understand?
It's been shown around all the German shows over the last few weeks.
|Thread: Dead Lipo remedy?|
I was about to write a long piece about LiPo chemistry, but it appears from posts today I'd be wasting my time.
I can't think of a commercial LiPo charger that will charge a LiPo if it's under 2.5V or thereabouts, and absolutely not from zero.
This isn't something the charger designer forgot to incorporate, it's a safety feature, a safety feature most here seem to think it's fine to overide. It's there because over discharging the cells permanently changes the cells chemistry, and therefore, is a clue they shouldn't be recharged.
Yes, I used the words 'utter lunacy'. Sorry if that's a bit strong, but nothing I've read here has changed my mind, inlcuding the gem above, "if the battery has a CE marker, it will be fine."
Edited By Guvnor on 12/05/2018 19:28:34
I do have some knowledge of LiPo chemistry and charger design.
Why do you think LiPo chargers refuse to charge LiPos who's V has dropped below a certain threshold, usually preset to 2.5V with a small load? Most commercial chargers use COTS chip sets, TI in particular. Clever ones WILL give a short gentle kick to try and revive a low V cell, but NOT from 0V. The charger chipset designers will assume that if the starting V is under 2.5V, the cell cannot and must not be charged... Have a read here: https://www.digikey.co.uk/en/articles/techzone/2016/sep/a-designer-guide-fast-lithium-ion-battery-charging
From this link:
deep discharge, like overcharging, can damage the cell.
Edited By Guvnor on 12/05/2018 00:16:03
Edited By Guvnor on 12/05/2018 00:17:24
If you're happy to take these risks with no understanding of what's going on between the plates then that's fine, go for it.
You obviously know nothing about LiPo chemistry.
Which part of "This is a dangerous situation which can ultimately cause a short circuit between the electrodes." is a mystery?
As the battery was discharged to 0V, then forced back up, those lovely copper strands are right now shorting between the cathodes and anodes. Not a huge amount and they will instantly destroy themselves. But one day the battery will be knocked or pressed and it will short properly.
Why take any risk whatsover with a damaged LiPo?
Please, just bin it...
It isn't "my opinion"...
The Zeus battery website as noted above for a start.
This is from the mpowerUK site:
Under-voltage / Over-discharge
Rechargeable Lithium cells suffer from under-voltage as well as over-voltage. Allowing the cell voltage to fall below about 2 Volts by over-discharging or storage for extended periods results in progressive breakdown of the electrode materials.
First the anode copper current collector is dissolved into the electrolyte. This increases the self discharge rate of the cell however, as the voltage is increased again above 2 volts, the copper ions which are dispersed throughout the electrolyte are precipitated as metallic copper wherever they happen to be, not necessarily back on the current collector foil. This is a dangerous situation which can ultimately cause a short circuit between the electrodes.
There was a big feature on LiPo safety in a recent RCM&E. I don't understand why people can't see that an overdischarged LiPo, no matter how fine it seems to be, is a ticking time-bomb...
Edited By Guvnor on 11/05/2018 19:43:47
Your choice. The cells may appear to be working but if you understand anything about the chemistry of Lithium cells, you will know that the strucure of the cells IS damaged.
From Zeus batteries website:
Over Discharge Conditions
Typical rechargeable lithium cells can safely operate down to 2.75V/cell. However, when an unprotected lithium cell is discharged past the minimum voltage level you run the risk of damaging the cell and ultimately lead to degraded cycle-life, unstable voltage characteristics and swelling of cells from internal chemical reaction.
Sooner or later, that battery might do something unpleasant.
I wouldn't like to be around when it does...
I just can't understand why anyone would risk a LiPo fire for the sake of a £13.75 battery...
Edited By Guvnor on 11/05/2018 18:45:56
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