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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: The Seagull E-Pioneer thread
13/08/2013 15:23:00

Hi Bob

On the test runs I did, I found that with a 3600 4S battery, I could run it at full power for half a minute (ie take off), and then I could easily get 15 minutes out of it with the wattage down to 150. In actual flight, I set my timer for 8 minutes, and I also have telemetry on board to warn of low battery. On an 8 minute flight I usually put back in about 2000mah, rarely much more, and I have plenty of time for a few more circuits if I am waiting to land or you-know-what the landing. I find my concentration span is rarely greater than 10 minutes. Don't know if this is an age thing.....surprise

The 12x6 is the recommended prop. I did try all sorts of different props on static tests measuring current, wattage and static thrust, and the 12x6 was the most efficient:

10x6 Max current 35a max static thrust 1.66kg

11x7 Max current 40A max static thrust 1.8kg

12x6 Max current 50A max static thrust 2.26kg

12x8 Max current greater than 60A static thrust @ 60A 1.99kg

These results were taken using the same battery throughout, hence the variation from the earler figures. As can be seen, your instructor has it wrong way round (an ic man?) and a higher pitch prop simply increases the current, in this case high enough to blow either the motor or an ESC.

The EP is quite lively with a 4S, and it sounds to me like you are flying on too much throttle. You can easily throttle back to a third and it will still happily fly comforably in most winds. At half throttle with a 12x6 it uses 15ah with a static thrust of 1.1kg, whereas you seem to be averaging about 25ah. Another issue could be that you haven't set the end limits of your ESC correctly, so the throttle appears to be lower than it actually is.

When you have your next lesson, try, or get your instructor to try a few low passes and see just what throttle setting will give confortable handling. I thiny you/he will get a surprise!

Hope this helps.

13/08/2013 12:35:47

Details of the safety plug:

safety plug 2.jpg

 

safety plug mount.jpg

I used a couple of M3 blind nuts in the mount, and glued an XT60 into it. Then I built up the wiring harness as follows:

 

wiring harness 2.jpg

I fitted an XT60 onto the speed controller so the whole thing is plug in, and all the electrics can easily be removed if required.

Sadly, this assembly was editied out of the articles.

Edited By Martin Phillips on 13/08/2013 12:37:01

13/08/2013 12:18:37
Posted by Phil Winks on 12/08/2013 21:45:10:
Posted by Martin Phillips on 12/08/2013 21:23:53:

There is about 3 degrees of side thrust on the motor built into the motor mount, which is slightly offset in the bulkhead to bring the front of the motor into the middle. Looking from the nose, towards the tail, the motor points about 1cm to the right of the vertical tail fin. On the above configuration this amount of side thrust is fine.

side thrust to the left side of the aircraft is a new one on me martin, honestly in knocking on 40 odd models either built or owned I don't think I've ever seen that condition and checking my E-Pioneer shows absolutly no sign of side or down thrust whatsoever is this possibly a result of the incorrectly assembled motor mount box I wonder?

Phil


If you read my post again you will see this is right thrust not left. The EP definitely does have side thrust built in.

12/08/2013 21:23:53

On the tests I did with my Emax 2820/07 with a fully charged new 4S battery driving a 12x6 prop, I got 675 watts, and a maximum static thrust of 2.3kg. However, as expected drawing 50 amps soon pulls the battery voltage down, hence, I suspect the varying figures. Maybe some are measuring average power over a period of time, or it could be due to the condition of the battery, i.e. its internal resistance. The BRC maximum wattage figures are lower than those quoted on the Emax website.


**LINK**

I notice Emax quote a weight of 144g, BRC 145g, and Giant Shark 159g. Someone has to be wrong!

After half a minute at full throttle, the battery voltage drops from 16.86v to 14.97v, reducing the current to 45a and bringing it down to a safer range. To get a thrust of 0.75kg, the 2820 uses about 9 amps, i.e. reducing the throttle somewhat greatly reduces the current drawn.

There is about 3 degrees of side thrust on the motor built into the motor mount, which is slightly offset in the bulkhead to bring the front of the motor into the middle. Looking from the nose, towards the tail, the motor points about 1cm to the right of the vertical tail fin. On the above configuration this amount of side thrust is fine.

Thread: Phils E-Pioneer assembly
09/08/2013 12:03:24

The most difficult things I found about building even an ARTF is getting the right components that not only suit the model but ensure it is balanced once completed. This was one of the features I deliberately included in my series of articles, to take away this major unknown. I also built on the experience of over 100 flights with the plane so I understood its strengths and weaknesses. You have opted for larger servos, which has meant enlarging the openings, but there is a bigger problem, weight. The construction of the EP is somewhat unique, though becoming more common. I used 12g metal gear servos and the supplied connectors. They are very easy to adjust at the servo arm end. Remember that simple "direct linkages" such as this don't need the torque of systems that have to drive snakes etc. Modern servos have a great torque anyway. I've had no problems with these servos.

Your problem is going to be weight. All that extra weight in the tail 18g per servo, 36g in total will require 2.5 /3 times that weight in the nose, i.e. nearly 100g It is not possible to move the battery forward to counteract this.

 

Edited By Martin Phillips on 09/08/2013 12:04:34

Thread: Field etiquette
08/08/2013 15:24:47
Posted by Tom Sharp on 08/08/2013 00:01:11:

One call you dont hear to often nowadays is "Interference".

That's true. Its probably because the committee don't like you talking about them like that.

Thread: The Seagull E-Pioneer thread
07/08/2013 14:33:05

I actually used an Emax 2820 which weighs in at 144g, which is about right given that you have bought a much heavier motor.

06/08/2013 12:12:01

Tony, the ESC can be velcroed in the bay underneath the battery compartment. If using a 3000-4000 capacity battery theres not a lot of room in the battery bay. Know about the link, they are available in the US. As. I said in the article, I suspect it wont be long before something like it is available here. My plug is glued to a small ply base which is then screwed into the side just in front of the wing. The ESC, safety plug and leads to the battery can then easily be removed without any soldering.

John, I have smallish hands, and find using a tranny strap very useful. I hang the loop of the safety plug on that, it works for me. Its always useful to have a spare though, long grass is a marvellous magnet.

Sadly I did not do the photos for the article, and they did not put a safety plug on their version. Am not at home now, but when I get back in the next day or two I will post a piccy. Where I have fitted mine seems fine, it is clearly strong enough the plug has probably been inserted at least 100 times or more.

On the subject of wiring, 14swg is quite adequate for the power leads, and makes soldering much easier. The way such cables are rated gives a wide tolerance to allow thinner cables to be used in situations such as this.

Thread: Afternoon treat!
05/08/2013 22:55:46

I have a Panasonic bridge camera and really like the viewfinder. If I use the screen I need my reading glasses, however I can adjust the viewfinder to suit my eye without needing glasses. Thus I can keep both eyes open and see the plane and see through the viewfinder

Thread: The Seagull E-Pioneer thread
05/08/2013 22:42:07
Posted by Phil Winks on 05/08/2013 19:49: much

esc prob in the back of the motor mount though possibly in the bty bay given its better to extend the motor to esc leads than the bty lead.

another thing I intend to do is use twisted servo extension leads, a throw back to 35mhz days to help prevent electronic noise to the RX.

I will be making bespoke ext leads to keep things tidy, not difficult if you are half decent at soldering, otherwise buy the closest length above that needed and you will need 5 possibly 6 depending on esc placement.

The ESC goes underneath the battery compartment. This keeps it well balanced with a 4S battery so long as it weight in at around 400g or less. Twisted servo extension leads are unnecessary. Simply keep them short.

You need 2 extension leads only, one for the rudder and one for the elevator. The rset should easily reach. A 2.4g receiver is so light, its exact position matters little. You will also need a short Y lead for the wing servos.

At about 50p each, why bother to make your own leads? It must cost you more than that to make them.

05/08/2013 22:25:24

The turning circle really does not matter much, most instructors will suggest you do not bother with a steerable nosewheel. In real terms 4-5 metres is fine, any less and it will simply tip a wing instead of turning. What is critical thought is to allow enough room for the battery, otherwise it will foul the servo.The wing joiner tube is plenty strong enough. In a crash you will probably bend the aluminium tube quite significantly, the wings will be undamaged, and the fuselage will probably split at the former where it is joined to the front part of the fuselage. Believe me I've been there. If the wing joiner tube is too strong, you may end up with far more serious damage elsewhere.

Before I wrote the articles I used 4mm bullet connectors for the safety plug. I did find that eventually the bullets did push back into the housing with time leading to total power failure. The XT60 was suggested for good reason.

I would not try to hide the safety plug. It would be all to easy to accidentally have it connected and not realise. It needs to be visible. Hiding it could be more dangerous than not using one at all, you might think it is not connected. For me, safety is far more important than aesthetics.

A battery cover is quite a good idea in winter when the ground is wet, however you risk overheating the ESC with limited airflow at other times of the year, and space for one is tight. The battery will also run hotter reducing its lifespan. Get decent velcro straps, the sort with a buckle on them which are much stronger, and you will not have problems with the battery coming loose.

 

 

 

 

 

 

Edited By Martin Phillips on 05/08/2013 22:26:47

Thread: Evans Volksplane free plan for beginners?
05/08/2013 13:22:23

First rule of thumb when building from these plans is to assume the plan is wrong. You'll usually be proved right several times over.

Second rule of thumb is that the narrative will always be missing at least one crucial part of the build.

Happy building.

Edited By Martin Phillips on 05/08/2013 13:24:32

Thread: Model Restraint
02/08/2013 17:52:54

Presume you mean a Deans plug for the battery? Conceptually no different except that it is placed on the outside of the model where it can be easily fitted and removed on the flying field.

Frankly, any slight delay on the flying field is simply tough. After all its their safety as well as yours. The pre-flight checks take just seconds, and surely even the ic boys check the operation of the control surfaces on the flying field? I've never had any complaints when doing this.

02/08/2013 16:53:15

For me the most effective solution is fitting a safety plug to every model. I do not fit this until I am on the flying field with the model in the take off position. Once plugged in (standing behind the wings), I then perform final safety checks. The safety plug is removed once the flight is finished, but before the model is removed from the flying field. With the safety plug removed then it is perfectly safe to disconnect and reconnect a battery, even if the battery is underneath.

Using this procedure no mechanical restraint is necessary.

When testing at home or occasionally on the field, then I use a mechanical restraint, and the safety plug provides a strong message, armed and possibly dangerous.

The only possible flaw in this is a badly constructed model where the wiring is such that a short could occur, but then any badly constructed model is a danger.

Thread: New Spektrum DX9
01/08/2013 22:09:04

Hmmm. Like the idea of voice alerts for the telemetry.

It also looks as if they have improved the menu roller. I find mine on the DX8 perhaps the worst part of the tranny as it is quite slippery and you end up pressing a tad too hard and selecting something instead of moving onto the next menu element.

Seems to have the dual antennae too.

Just noticed. Experience level: Advanced. Lets me out then. crying

Edited By Martin Phillips on 01/08/2013 22:10:50

Thread: Goosed Lipo
01/08/2013 22:00:28

If you Google this subject you will find several articles on measuring IR, together with a few ideas for making your own tester.

Testing the IR of a Lipo is a relative test, i.e. you test it when it is new, and at regular invtervals thereafter. As the battery ages you will see the IR rise gradually at first, and then when the battery is near the end of its life, the IR will dramatically increase.

The HK one is pretty cheap even if you use it for just this one function, and far cheaper than finding your battery has expired just as you open full throttle in an awkward flying situation.

Its saved me quite a bit of money too. I have found that the most expensive quality batteries that I have bought are starting to fail/have failed  much quicker than some of the cheaper batteries.

Edited By Martin Phillips on 01/08/2013 22:02:33

01/08/2013 19:25:39

You cannot easily test IR with a simple multimeter. I also have flight pack telemetry with a warning, and those batteries which give an early warning signal are the ones where the IR has significantly risen. As Steve says, IR gives a very good health check for batteries if you monitor them regularly.

It also has a great servo tester that uses the pulse width so you can get very precise centring trim when setting up a model. You can also check normal end throws which are less than the maximum possible throws of the servo. My cheapo servo test is way off the middle point.

01/08/2013 16:46:30

Erfolg, get yourself one of these and take any guess work out of it. It will measure the internal resistance for you:

7 in 1 meter

**LINK**

Thread: I thought I knew how the brake behaved.
30/07/2013 14:08:39
Posted by Steve Hargreaves - Moderator on 30/07/2013 13:46:08:

My understanding Erf was that a spinning propellor (braked or freewheeling) will ALWAYS produce more drag than a stopped one.....a spinning prop offers effectively a circular area roughly equivalent to the diameter of the prop where as a stationary prop only offers the surface area of its blades...much less in other words...

Yes but.... The spinning prop, due to its shape is cutting through the air rather than acting as a circular barrier.

30/07/2013 12:24:11
Posted by Steve Hargreaves - Moderator on 30/07/2013 11:16:06:
If only the ESC could harness this energy & use it to recharge the flight battery.....true regen braking in the way of automotive hybrids....thumbs upsmile p

No reason why it can't. Any good at circuit design? There's a real winter project for you.

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