The Wright Stuff

I use Inwoods - it's local to me so saves postage. They will cut a bigger sheet to size for you, no problem, or if it's not in the shop, they will order it for you - arriving in 2-3 days.

The other thing to think about is that LiPo's generally don't self-discharge to any significant extent, or at least, they shouldn't do. There is an enormous gulf between 20% (about 3.7 V - the 'lower limit' for storage mentioned informally above) and the 3.0 V 'threshold' for permanent damage. I would strongly argue that if you store a battery at 10% - 20%, and it self discharges to below 3.0 V over a reasonable storage time (say 3-4 month winter break) then that battery was probably on its way out anyway...

I really don't believe it's particularly sensitive. Anywhere between 20% and 50% isn't going to make any measurable difference to lifespan unless you study a dataset of thousands of batteries. As Matty says, the only real rule is not to store them fully charged. I'm not aware of any good data on lifespan. It would take 2-3 years to collate such data, and since the battery technology will have evolved in that time, it would then be 2-3 years out of date.

Posted by Biggles' Elder Brother - Moderator on 19/09/2018 11:44:33: Posted by Devcon1 on 19/09/2018 02:56:58: Intrigued to find out what the twist will be and the performance. Sorry if I dissapoint you Devcon - but the "twist" is just that I think its a bit unusual to be doing an electric conversion of an electric conversion! Edited By Biggles' Elder Brother - Moderator on 19/09/2018 11:45:44 ...and here I was wondering whether the 'twist' was in the wing or in the fuselage, and how it was going to be straightened out...

This argument has two sides, both equally valid. It depends upon the cost of your batteries and the relative value of your time. Batteries will last significantly longer if they are consistently treated well. But monitoring charge and discharge cycles is time consuming. If you are retired and have lots of high C 6S packs, then it's probably well worth taking care. If you fly foamies with bog standard 2200 mAh 3S low C packs, then the relative reward for investing the time is much less. I have a full time job, a two hour commute, and two young children to sort out each day. To have time to carefully manage my batteries, I would need to take a day off work every week, unpaid. For that, it's much much cheaper to simply replace my batteries every couple of years or so... So there we are, while technical information is useful, personal circumstance is relevant too... Edited By The Wright Stuff on 19/09/2018 09:47:14

Any update Tony? I'm interested to know if you got any more answers!

Posted by andyh on 17/09/2018 14:25:57: Posted by Cuban8 on 17/09/2018 12:20:06: ... we get tarred with the slightly odd and boys with toys brush. pretty accurate then +1

Posted by Ian Jones on 17/09/2018 10:35:41: and I think taken from "Joe Soap" point of view probably didn't to our hobby any harm, though I think they could have done better for us. I think on reflection, that 'we' were not the target audience. Not by a long way. Joe Public wants to see a lot of hairy flying, and crashes - it's part of the entertainment.

Posted by Don Fry on 14/09/2018 15:17:12: Edit. A nose heavy plane does resist the nose coming up. That's why you need some up trim to keep it up. And the up trim gets more uppy when the power comes on, or it increases speed because of there is more wind, and force acting on the elevator Since no up-trim has been added in order to produce level flight, in fact quite the opposite, a bucket load of down-trim has been added to ensure straight and level flight, I would agree with Nigel that it is unlikely to be the CoG too far forward.

Posted by PatMc on 14/09/2018 12:25:26: If a model is trimmed to fly S&L when it's nose heavy it will have to have more difference in incidence between wing & elevator. This means that any increase in power/speed increase the lift causing the nose to rise. This is the basis for the well known, but apparently not well understood, "dive test". Have a look at the "dive test" explanation about half way down this page. The test was concieved with gliders in mind & it's not necessary to actually dive a power model as the only reason for the dive is to cause an increase in speed, increasing opening the throttle of a power model has the same effect. It can still be useful to separate the effects of CoG / elevator trim versus thrust lines. If you want to check the CoG independently of knowledge of whether the thrust line is correct, you need to build up speed without using the throttle... ...a dive, of course, is quite a convenient way to do this. Of course, it doesn't have to be vertical, a 'dive' can be really quite shallow, provided it produces the required increase in speed...

I ask once again (though I'm beginning to suspect my posts are invisible): do we actually have any statistics that say the number of cars being hit is increasing in a statistically significant way? If not, why are we squabbling about it? Small number statistics can be influenced by a great many factors. For all we know, it could just have been one really expensive car that got hit. The difference between mean and median is instrumental when drawing conclusions. Or it could be that car insurance companies are becoming more insistent on following up liability, rather than just paying out. Edited By The Wright Stuff on 14/09/2018 12:51:15

...bad statistics...

As I've said already, without more information than any of us have available at present, you CANNOT equate 'higher total value of awarded claims' with 'more accidents'. You just can't. It's bad statistics.

Posted by Cuban8 on 13/09/2018 11:05:20: So..... are we saying that if modeller A crashes his model into modeller B's car and causes damage, modeller A should in the first instance, report the incident to their insurer as they would on finding any other malicious or accidental damage to their parked car? The cost of the repair would then be recovered by A's insurance chasing B for the money? At which point BMFA step in and protect B from legal action. In principle, this is exactly how third party insurance should work, yes. It has to be proved that the modeller who crashed was negligent. If it was deemed to be an unavoidable accident, then no BMFA payout is required. It's the car insurance company's hard luck. Perhaps there are short cuts applied in practice, though, like BMFA paying out in anticipation (perhaps to save legal costs) if it seems likely that a case could be brought to bear...

Posted by Piers Bowlan on 13/09/2018 10:46:39: I wonder how far away they would park their cars if they had to claim off their own motor insurance policy if their car was damaged by an errant model aeroplane. I guess the BMFA think it is OK because that is 'what they have always done'! It would be interesting to see how the insurance premiums might fall if members cars were not covered by BMFA insurance, assuming that claims for damage to members cars is a significant part of total claims. Less risk=lower premiums= less deficit at the end of the year for the BMFA. It's not quite true to say that members' cars are covered. Damage repair WOULD be paid by the car insurance in the first instance. The BMFA insurance only kicks in as third party liability, so there is no guarantee that the car repairs would be covered (in fact, I'm sure that many claims would be rejected). All that is covered is the eventuality that a member is sued for the damage. Edited By The Wright Stuff on 13/09/2018 10:52:53

A 20S power system is starting to become serious!

Posted by CARPERFECT on 12/09/2018 23:56:56: The bit in the middle about only being £20,000 short fall. 35,000 x 4 = £140,000 ? So why do we need an extra £120,000 ? I suspect that there are four elements to this: Economics can be complicated. We are shown only a much simplified version of the numbers. There is likely to be more to it than we generally appreciate (or 'need to know'. The £20,000 shortfall is for the one year, there is also a need to repay deficits from previous years. The £4 may well be 'haggled back' to £2 or £1 at the AGM, hence the initial proposal is more than actually needed. Of course, it may be that the subs increase itself affects the numbers renewing, so that the £20,000 is based on renewal rates at the current £34. Edited By The Wright Stuff on 13/09/2018 08:48:37

I watched on catch-up last night, and to be honest my response was quite neutral. It was okay. It didn't blow my socks off with excitement, but I didn't cringe either. I liked the format and the competitive element, and I thought the 're-writing history' aspect worked very well - I guess (having been to the BoB pyrotechnic events at shows like Weston Park) I was a little underwhelmed by the models and the flying. What really disappointed me was the lack of decent video footage of the models in the air - it would have been nice to see a few close up slow motion shots to capture the key moments. There was lots of talk about slow, realistic, smooth flying, but this wasn't really evident in the footage the viewers saw, which was lots of manic zipping around in the distance. But overall, good production. It could have been a LOT worse. Edited By The Wright Stuff on 12/09/2018 08:51:06

Posted by Nigel R on 11/09/2018 12:44:54: due mainly to significant increase in claims for members crashing into other members vehicles or expensive aircraft in the pits area. so, why have we collectively all got worse and less safe at flying? We can't tell from that single sentence whether: There have been more accidents. A higher proportion of accidents are now turning into claims. The number of accidents and claims are the same, but the value is higher. Common sense would dictate that it's most likely to be a combination of all three. But without detailed incident statistics, it's probably fruitless to speculate...

BEB, Bob, I agree 100%. The bit I'm missing is quite where the 'cavalier approach' perception arose in the first place - reading back through Dave's posts, I felt they were polite, measured and suitably caveated already. I see no reason why he wouldn't progress through testing in exactly the systematic manner that BEB has correctly outlined. Is the actual issue here simply that it's off-topic for a 'does it exist?' OP question? In which case, guilty as charged for the lesser crime! But seriously, I'd be happy to hear about Dave's progress in a suitably titled new thread, making clear that it is not intended for beginners, of course!

Posted by The Wright Stuff on 10/09/2018 08:29:46: Posted by Ikura on 09/09/2018 18:33:20: Whenever you post a description of what you are proposing, you don't avoid the responsibility of what you say or do. I'm sorry Ikura, BEB, but while I agree with a degree of caution in this particular thread, I can't agree with the subsequent generalisation. Most of what we talk about on this forum is to some extent proposing, doing, or testing aspects of model building and flying that were beyond or to the side of what the manufacturer intended. That's what makes the hobby so diverse. Firstly, if you've ever used a different glue to the manufacturer's recommendation, or you've fitted an electric motor when the instructions called for I.C., or programmed an open platform Tx, or used after market receivers not authorised by the Tx manufacturer, then surely this is from the same hymn sheet... who decided where the line was drawn? Secondly, I think there is a huge difference between describing an approach one intends to experiment with, and recommending it to others as an accepted practice. Of course there is some responsibility to a degree, and this is an area for common sense to be applied, but ultimately, the sole responsibility is with the pilot/operator. The ANO is very clear on this point.

double post Edited By The Wright Stuff on 10/09/2018 08:46:58

Please can I ask a potentially daft question? Presumably the model can 'know' its groundspeed via GPS, and it can know its attitude via gyros. But how does it 'know' its airspeed when it's landing itself? Without an external airspeed sensor, how can it compensate for a steady wind?

Thanks for posting ARC, that's a fantastic looking model and an enviable strip!!! Are you going to fly it on BoB day?

+1 for soldering, rather than replying on connectors.