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Member postings for Andy48

Here is a list of all the postings Andy48 has made in our forums. Click on a thread name to jump to the thread.

Thread: Covering Iron - worth buying?
16/01/2013 19:22:02

Heat guns

Rather than the modellers heat gun I use one of these made for crafting, hence the pink (!!!) colour. The 2 speed ones are best, and not too vicious for solarfilm. They are great too for heat shrink. At about £13 you can't go wrong.

**LINK**

Thread: Electrified Hype
13/01/2013 19:58:02

Answer: wrong motor and wrong prop. That 300kv will only give you 1600g of thrust with a 14x7 prop, barely enough to lift the brick let alone the plane.

The 500kv will give you 2600g of thrust using a 13x8 prop.

If you have not set the ESC up, then you will not even get the spec level of thrust.

13/01/2013 19:28:19

1. faulty motor

2. faulty esc

3. bad joint somewhere

4. poor connection somewhere

5. ESC not set up correctly for motor

6. Wrong version of G60

7. wrong prop for motor version

Thread: Underperforming Lipos or something else ?
08/01/2013 20:38:24

Nooo! It isn't as simple as that. Can I quote from the Emax GT box "The motor efficiency is higher when it is run before maximum current specifications."

What happens is that as the maximum current is approached, the efficiency starts to drop off and actually you could well have less output power, though be using more current and draining the battery faster, which is exactly what the orange curve on the very relevant graph above shows.

Thread: Reading and viewing
08/01/2013 15:05:05

Alan

Can I suggest you Google "U3A", and look for a local group.

U3A is designed for people of our age, and usually offer a wide range of activities and groups from walking groups to book clubs. It sounds like you would really enjoy at least the book club, not only for the chance to discuss a series of set books, but also for the like minded people you would meet there. There are 3 in our U3A who also also a member of our local model club. Cost is usually minimal.

Martin

Thread: Underperforming Lipos or something else ?
08/01/2013 14:57:01

graph

Not entirely sure about this, but I seem to remember reading that the maximum efficiency of a brushless motor is at about a third of maximum load. Found the above chart for a brushless motor which would seem to indicate that too, and also show that increasing the torque load (ie prop size/pitch) does not always lead to more power.

Emax are very specific about prop size, I would assume that this the most efficient size, and a larger prop will draw more current but may not give an increase in performance.

I do know from some of my tests that the efficiency is higher at lower currents. I must experiment more with a few bench tests. Hmmmm.

Thread: How untidy is your workshop?
07/01/2013 22:01:54

I am in the process of redecorating my workshop so it is rather untidy. One of the attractions of buying our house some years ago was a large room built onto the back of the double garage. It has a double brick wall, which I had cavity filled along with the rest of the house. New double glazing, and a new felt roof. Then came a sink and water, and lots of cupboards.

I also do quite a lot of woodwork and one of my best investments was a dust extractor. That lives in the garage and I have ducting through into the workshop. Little or no noise and NO DUST.

Somehow though, I never seem to get it quite tidied before the next project starts.

My workshop is great. I can usually sneak parcels in there before OH sees. smiley TV and old Sky dish for company, plus kettle and I'm all set.

Thread: Underperforming Lipos or something else ?
07/01/2013 21:51:22

Steve. Sorry for getting the wrong motor. Doh!

However if you look at PatMc's link and the one I gave above from the EMax website, you will find that the GT2820 /07 will give 41amps on a 4S battery, but 26amps on a 3S. Your answer probably would be a 4S battery. I have tried various propellers on the BL2820, and found that the Emax specification of a 12x6 proved the best. Interesting though, with a brand new Lipo, with a really low internal resistance I could only get 51amps not the 59 as stated.

I have yet to try fiddling with the ESC timing setting. This may make a difference. Failing that, if you cannot fit a 4S, you could change to a GT2820/04 and get a little more power. Just a thought.

Thread: trouble getting your planes into the shed?
07/01/2013 13:08:40

And yes! There's the kitchen sink too.

Thread: Underperforming Lipos or something else ?
06/01/2013 20:23:53

I was being conservative, a new Lipo will give over 2.2kg of static thrust with a 2820. Believe me I've been doing quite a bit of research on this motor of late...

06/01/2013 20:08:36

The Emax 2820 should use an 11x7 propellor and draw a max of 38A with a 3S. See manufacturers spec: **LINK**

If it still gives a low wattage, then possibly something wrong with the Lipos, or maybe a bad connection. Maybe your Lipos are getting a bit tired, and the internal resistance is rising fast.

I can confirm a 4S with a 12x6 will draw just over 50amps and give a thrust of over 2kg.

Edited By Martin Phillips on 06/01/2013 20:09:17

Thread: Electric newby starting a Wot4 E and requiring advice please
06/01/2013 16:35:11
Posted by Biggles' Elder Brother - Moderator on 05/01/2013 00:23:53:

Hi Keith - well that field battery will just about about do for 3s batteries - but allowing for charger losses etc you will only get two battery charges of it - at best! You see your lipo's are 11.1v - pretty much the same as the field battery - and they need 2.2Ah to fully charge. So two charges is 4.4Ah, assuming your charger is about 80% efficient that 4.4 Ah will take about 5.5 - 6Ah out of your field battery! Doesn't leave enough for a third charge.

You really need a leisure-style 12v lead-acid job to recharge at the field. I use a 70Ah battery - but I have a lot of 6s batteries, you could probably manage well with something a bit smaller - say 30-40Ah or so.

BEB


Can I suggest a compromise? A 24ah gel battery comes in at £30 delivered. **LINK**

This is half the price of a leisure battery, and half the weight, yet should be good for many more flights.

Can I also add a plea about safety? Any of these batteries are quite heavy lumps, and god forbid, in an accident, could be much more dangerous than the accident itself. Imagine being hit on the back of your head by a battery travelling at even 30mph after your car stops suddenly in an accident. The safest place is in the passenger footwell, or the rear passenger footwell.

 

Edited By Martin Phillips on 06/01/2013 16:38:35

Thread: I have been thinking, why bother buying. if not manufacturing
06/01/2013 15:03:17
Posted by Tom Sharp 2 on 05/01/2013 01:12:03:

Think British Leyland.

I'm shuddering at that particular thought.

Thread: January 2013 Issue feedback
02/01/2013 14:08:41

Lee

In answer to the first part of your question, yes, considerable expertise. In answer to the second part, no.

It made an interesting combination when I was learning to fly.

31/12/2012 11:23:46

Hi Max.

Thanks for the comments.

Do I have to confess now???

As I think I have already said, I have had an on/off series of attempt to learn to fly, not helped by several job changes that meant moving from one end of the country to another. When I retired, I made a serious attempt to learn but found some down at the club so unhelpful. One day a few years later I decided I was either going to do it this time and get my A certificate or find another hobby. Out came my very old Apache trainer with an Irvine 46 in it, all faded down one side where the oil had had its way. After not a lot of fiddling the engine started ( it was a super engine), and with a quick once over, down to the club I went. The atmosphere had changed and it was much more welcoming.

After a few flights, I decided I wanted another plane as a backup. After much research and thought I bought the Seagull Innovator, and thoroughly enjoyed learning on this, so much so, the old Apache was usually left at home. However, at times it proves a little light. The day of my test came and another flyer and I were down to take our test. He took his test, I managed to do something silly through nerves and blew up the ESC. In the end I took my test on the Apache instead. I do remember being asked questions on safety for both IC and electric.

After that I bought the larger E-Pioneer to go with the Innovator and it literally flew out of the box, and during this time I realised how much work I had had to do to specify all the things you have mentioned. There is so much confusion even on the web that it was quite difficult. Motors seem to have amazing differences in specification for the same motor depending on where you read it, hence the idea for the articles.

In the end, I did the homework - lots of it, beefed everything up a bit to provide a decent safety margin. I measured current and wattage for different propellers, and checked the performance using a static thrust test with the model hooked up to a sensitive balance on a smooth surface. Thankfully I have that sort of a background so I quite enjoyed the challenge.

The servos seem to be no problem in damp or wet weather, other things are though as we shall see later. Easily overcome once you are aware.

With the motor/esc/lipo combination specified the plane is just under the recommended weight of 2.2kg and will fly vertically - the static thrust exactly matches the all up weight. However it is still easy to fly, and makes taking off far less hit and miss, or should I say, bounce, flip and crunch. In all but the windiest conditions this combo will have enough power to do both parts of the test no problem, though swapping a battery only takes a minute or two.On normal flying a 10 minute flight will half discharge the battery.

Thread: C-160 Close shave in Germany
28/12/2012 21:44:03

Are the DM aware that planes have pilots?

28/12/2012 21:35:50

3 out of 10?

Hmmm, that's pretty good for the DM, they'll be pleased with that. cheeky

Thread: James May's Toy Stories: Flight Club
24/12/2012 18:27:48
Posted by KingKade on 24/12/2012 16:24:50:
Posted by Simon B on 23/12/2012 23:32:41:

Until the poor sods go into Slough and get ignored

Edited By Simon B on 23/12/2012 23:33:16

Made me laugh when the store guy said 'have you tried the internet?' exactly what slouh model centre wants you to do, as aposed to walking in and picking up models, and heaven forbid ask some questions!!!

I knew there was a reason for moving away from Slough.

24/12/2012 18:26:51
Posted by Stephen Grigg on 24/12/2012 17:02:56:

Thoroughly enjored the programme we should all fly our models from helicopters no complaints from neighbours.

You don'tknow my neighbour, he'd just find something else to complain about.

Thread: January 2013 Issue feedback
17/12/2012 17:21:22

BEB, you and Erfolg are absolutely right, however this short interaction has actually been useful feedback to me, and Winco Steve has clarified his thoughts well, and, hopefully will enable me to keep the future articles balanced. Thanks Winco for your comments.

If I may comment on Lidsay's very valid post, when I took my "A" test, I was asked questions on both IC and electric, and looking at the test requirements this should clearly be expected. The "A" test is something I will be covering in due course, and this is a handy reminder to ensure I do mention familiarity with both "disciplines" before taking the test.

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