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Old Dec 24, 2012, 07:24 AM
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Originally Posted by PeterVRC View Post
de-tuning (via higher IR) can often be required to keep a setup running in a sustainable area.
I have never had a battery puff since I always ease into my length of flights to find out the limits, size things appropriately (or try to anyway), and charge conservatively. De-tuning via using a higher IR battery would seem the catalyst for such an event by placing more stress on the battery. Kinda like running a 20A item on 22ga wire .... the wire takes the hit and melts.

Lowering the throttle endpoint seems to make sense to me to keep things within spec. Finding out the spec (limit) is the key I guess but one cannot ever determine the level of manufacturing quality. One motor may take 1100W forever and the next one smoke @ 900W. Left thumb training would do it too but in the course of a flight, one might tend to just go for it. With a mechanical limit set that couldn't happen. You mentioned earlier that these motors are cheap so if you toast one, just get another! OOPS, there goes another one! I've learned a lot about EDF's here in this thread... Thanks
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Old Dec 24, 2012, 11:53 AM
Wats the worst that can happen
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Canada, BC, Surrey
Joined Jan 2009
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Thank-you for the informative response.
I actually did buy two metal trunion version as well - so I'll use those instead.
The front landing gear I've already completed with pull-pull steering. I know you're not a fan of that. I tried my best to get the linkage working, but couldnt. It kept binding. I have another unbuilt Meteor - I'll put more effort into making it work (and refer to your blog) when I need to build this one.

Those sprung oleos look like they'd add a significant amount of weight.

btw. Did you ever try the two servo elevator idea? I still havent re-maidened mine since I installed. I attempted to, but the electrical system shorted out - i believe caused by the larger-style retracts. It certainly has much more authority than stock. It should be able to perform tighter loops now no doubt.



Quote:
Originally Posted by PeterVRC View Post
I have those in my Meteor... but you want the Metal Trunion version really. They are much better... for a fraction more cost.
And I have sprung oleos, which you pretty well need if you want it to last long term... especially on grass! I take off from a cricket pitch, but land on the oval's grass. And it is fine doing that.

Metal trunion version of that retract:
http://www.hobbyking.com/hobbyking/s..._Trunnion.html

Oleo set:
http://www.hobbyking.com/hobbyking/s...Strut_Set.html
The oleos are a bit costly, but they are excellent and there isn't much else you could get to do the job as well anyway. I did use the stock wire legs/wheels, cut down to suit, for ages, so you can certainly do that to save money!

My installation is somewhere WAY back in this thread.
The main gear is SUPER simple.... but the nose gear takes a bit more time. Not too bad if you know what you are doing from experience, but if you don't have those clues etc it can be a big project!

The main notes are:
1) Nose: Make the leg fold FORWARDS
2) Mount the retract off its "top" - the side that is away from the trunion. Change the retract mount plate to the 'full' one. Just use one large plywood 3mm or 4mm plate put up into the cut-out nose area (part of the existing open area used too). Mount the steering servo into that same single plate (pre-do it all before epoxying the plate in!).
3) Use pushrod steering - I have an outline of doing that in my Blog (most people don't do it right, but if you do know how and why then they are the best system by far!)
4) Mains - just dremel out the existing plastic mounts to take the retract unit, that works fine and is strong... and dremel out some foam for the legs and wheels to recess into.
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Old Dec 24, 2012, 05:46 PM
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No, using higher IR does nothing to hurt the battery. It just reduces volts to the motor.
This reduces current. Thus power.
Less current through the battery reduces its heat.
So it all equalises out as fine. And is nothing at all like using 'thin wire to limit current' etc.

In ALL setups, no matter what battery you use, you have to test them and check the currents and temps, so that you run the battery at an acceptable level. You can do that all statically and will know what will happen before you even ever fly it. They will not use as much power in flight as statically (by a small amount), so statically is a good test.
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Old Dec 24, 2012, 05:51 PM
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After adding a few other planes a month and few back, I have not taken the Metoer out for a while now. It has a stress fracture at teh nose area, from a BIG crash long ago.... and the fact I mounted the nose gear folding REARWARDS, which later showed its shortfall !! Because the retract and main stress is all much more forwards where the nose is much thinner!

I have another Meteor waiting to be built, so that one I will do the twin tail servos and will be a 6S powered one. I am not sure when I will start that. It would need about one week allocated to building it all up.

I think the oleo weight is worth it. I never bother about weight is aircraft anyway - I consider them all to be way too light, versus the real scale mass/inertias they need to have to behave properly aerodynamically. So I never really run out of weight carrying ability... they are usually fully done up and still "too light" anyway.
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Old Dec 24, 2012, 08:34 PM
TakeOff=optional,Landing= Must
fg1972's Avatar
Australia, Melbourne
Joined Jul 2010
427 Posts
Anyone know the stock meteor weight with its fixed landing gear vs the weight after installing retracts & oleos?
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Old Dec 27, 2012, 06:46 AM
RAVI KOTHARI
Bombay,India
Joined Nov 2005
257 Posts
just love my Meteor, outflies my friends habu easily.
Powered with the leopard/minifan setup, she flies for a Good 6-7 minutes, its just amazing how potent the system sounds & the lipos are just mildly warm.
thinking bout getting another one, this time in the retracts Go..............
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Old Dec 27, 2012, 07:42 AM
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Quote:
Originally Posted by PeterVRC View Post
No, using higher IR does nothing to hurt the battery. It just reduces volts to the motor.
This reduces current. Thus power.
Less current through the battery reduces its heat.
So it all equalises out as fine. And is nothing at all like using 'thin wire to limit current' etc.

In ALL setups, no matter what battery you use, you have to test them and check the currents and temps, so that you run the battery at an acceptable level. You can do that all statically and will know what will happen before you even ever fly it. They will not use as much power in flight as statically (by a small amount), so statically is a good test.
Then I wonder why the 20C batteries puff up whereas the 30C batteries do not?
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Old Dec 27, 2012, 08:26 AM
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That will be because you used a 20C battery, which gave an end result of current (which is the result of motor impedance and battery IR) that was too much for the battery's specs.
It sounds like you should not be allowed to make choices of batteries, because if you ever puff any then you don't know what you are doing well enough.
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Old Dec 27, 2012, 10:14 AM
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Quote:
Originally Posted by PeterVRC View Post
That will be because you used a 20C battery, which gave an end result of current (which is the result of motor impedance and battery IR) that was too much for the battery's specs.
It sounds like you should not be allowed to make choices of batteries, because if you ever puff any then you don't know what you are doing well enough.
No no, I have never puffed a battery. Earlier in this thread you said you use them but that the 20C would puff if too much wot was used, but not the 30C

Quote:
Originally Posted by PeterVRC View Post
HobbyKing:

5S 3000mAH 20C Zippy $20
Works pretty well, but if you WOT lots it will puff. Still passable really, and a super bargain at $20!! Mine have lasted long term and at this cheap price you can afford to throw them away 'sooner' than a 30C for example.... but all of mine are still working fine.

5S 3000mAH 30C Turnigy $32
Only a fraction better power than the 20C, but doesn't puff if WOT is used a lot.
Higher C (more important is that it also means lower IR) means you will get more power because the volts dropped over the battery are less than for a lower C battery, but in this case of 30C versus the 20C, you don't see that much gain... it feels more like it is 25C versus the 20C Zippy.... or the Zippy is 25C and this one 30C.

5S 3300mAH 65C Nano $59
Double the price, but not double the performance! But enough more that you are likely to be asking for trouble with the stock motor! Lower IR means more volts for the motor = more power = over-stressing its specs a bit too far.

I would not advise going over the 30C for the stock motor.
I can't 'advise' using the Zippy 20C, because it is marginally over-taxed (runs overly hot for a long life) if you use WOT too much - but if you can take care of it (not WOT all the time!), it is that super bargain price and still performs very well!

These two (20C and 30C) are also still perfectly suited for use with a CS10/L2855-2300kv combo, if you 'upgrade' to that - for its better 'jet' sound. And their resultant motor power keeps it at a level it will last long term (the L2855).
I have not tried a Nano in that combo, but it should be fine - and more power - but would have to be taking the motor into the region of 'over-spec that will affect lifespan'.
If you do really want a more powerful result than the above (stock or CS10/L2855) I would advise a CS10/HET 2W30 on 6S. That is a long-life combo and would be 20% more power sort of thing - it should go over 1:1 thrust (might need a thrust tube to get its optimal output). But that is almost a $100 combo, whilst the CS10/L2855 is a $30 combo!
Sounds to me like it hurts the battery if it is puffing, or am I misunderstanding you?

Quote:
Originally Posted by PeterVRC View Post
No, using higher IR does nothing to hurt the battery. It just reduces volts to the motor.
This reduces current. Thus power.
Less current through the battery reduces its heat.
So it all equalises out as fine. And is nothing at all like using 'thin wire to limit current' etc.

In ALL setups, no matter what battery you use, you have to test them and check the currents and temps, so that you run the battery at an acceptable level. You can do that all statically and will know what will happen before you even ever fly it. They will not use as much power in flight as statically (by a small amount), so statically is a good test.
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Old Dec 27, 2012, 11:26 AM
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Quote:
5S 3000mAH 20C Zippy $20
Works pretty well, but if you WOT lots it will puff. Still passable really, and a super bargain at $20!! Mine have lasted long term and at this cheap price you can afford to throw them away 'sooner' than a 30C for example.... but all of mine are still working fine.
This didn't mean pasable to WOT them, but that they will puff if you use it WOT too much... so it is a passable battery to use for less demanding flying in the Meteor. As long as you kow what parameters it will be running at, you can make sure you use it within acceptable ones. And at $20 the 3000mAH 20C is a super bargain, so use it according to its capability. Their IR is not quite high enough to 'force' lower power - higher IR would drop motor volts more and thus they wouldn't run at higher Amps anyway - but seeing it isn't, you have to control that aspect yourself. In the Durafly Vampire, which has more ducting restriction, it does run in that 'forced' lower power region, because the ducting restriction limits what the fan can run at anyway. So even though bench testing shows the 20C is a bit low for that L2855-2300kv CS10 combo, the Vampire itself causes the parameters to run at lower levels and you can WOT it merrily as it will only run at 43Amps area anyway. The Meteor will run it at 50Amps area for WOT, so that is too much for a "60A Capable" battery to cope with for very long at all.

This is all on a L2855-2300kv in a CS10.... any changes to those items means the numbers will very likely change too. Thus why you have to test every combo to see what it truly does, so you can then change to a more appropriate battery if need be, or use the one you tested at a lower level seeing you know its limits.
Even if you go to a 3000mAH 30C (90A "Capable") you still have to test that, because its lower IR will increase the volts to the motor, and thus the max Amps it runs at WOT also - which then eats into some of that extra C leeway it has. Say, like the 50Amps in a Meteor on the 20C could move up to 54Amps on the 30C, thus 1.5x current leeway factor is now 81Amps (not 75Amps as before with the 20C's Amps result). So it now falls within the leeway needed (by 9 Amps).
In general, moving up in C does NOT take the power level (and thus Amps) up as far as the gain in leeway (due to higher C) gave you. So for eg, if 20C was marginal, and 30C would seem a good amount more leeway, it will not give "10C worth" but maybe something like 6C of leeway.

Meanwhile you still have to monitor those changes to see if the motor itself can cope with the step up in power. 20C, at 50Amps might have ran volts at 18.0v so Power = 900W..... 30C at 54Amps would be higher volts, say 18.4v so Power = 993 W... just thanks to the 0.4v the higher C could give. And now you have to watch WOT, not because of the battery, but because of the motors limits. So possibly a 25C's results would end up at a nice balanced total (say 950W) that meant both motor and battery can cope fine with any manner of flying it.
[All just made up numbers, in the region they would be, to show the results of different C's in that Combo, in a Meteor]

Go higher in C = even lower IR = more motor volts = more Power.... and maybe already by 40C it is now the motor that is the weak link.
So you don't just throw in 'a higher C', just as you don't throw in any old lower C either. Both directions hit problems for any given combo.... so you need to TEST it all out to work out the best solution, OR how to use what you do have or choose so that you don't stuff up something in the combo. (Battery, Motor, or ESC too if the Amps move up too high).

Quote:
Then I wonder why the 20C batteries puff up whereas the 30C batteries do not?
Explained above.
You might choose to use a certain battery, that is marginal (such as the 20C), and you have tested to know the numbers but flying with it is hard to truly measure what you have truly 'done' in-flight, over that time frame.... so if it was a battery that needed limiting its max power use, you might 'feel it out' - building up to it - to see how it comes down. But it will take many flights to find out, seeing they will all vary, so then you will also likely take the battery down to lower discharge levels on this, or that, flight. Then might find out your initial thoughts on how to use it were a bit amiss - even though you 'built up to it'. And often you don;t have a more correct battery... or like this case $20 for 20C (which is just passable to use) versus $35 for 30C, might make you opt for that 20C.
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Old Dec 27, 2012, 02:47 PM
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I know exactly what you are saying but you don't get what I am saying so, never mind. Enough is enough
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Old Dec 27, 2012, 04:05 PM
Gotz tha Jet Feeva!!
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United States, GA, Kennesaw
Joined Dec 2011
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Got a spare airframe that I'm thinking about glassing, and installing a 6S setup...
Anyone ever go that route?
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Old Dec 27, 2012, 08:57 PM
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Nope... LOL
But I have a second one which will get a Lander CS10 Alloy 6S setup I have for it. (Which might get tested ou tin the current Meteor - if I ever get around to that!)
I won't glass it... or didn't intend to. But I have been waiting for a suitable test case for WBPU/Glass, so I guess that is one of the top contenders to have it done.
I am just not sure about the added weight, which would have to be a few hundred grams then.... the glass & WBPU, filling, painting, more WBPU.... and the alloy 6S and battery are already a fair bit of extra for it to carry anyway.

Sounds better to test the 6S on it, leave it plain unpainted.... then work out the weight carrying ability before deciding on the glass. (It will have retracts and oleos, as per the current one).
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Old Dec 29, 2012, 09:47 PM
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I got a bit fired up over my Meteor today....... so I did repairs and some tests....

My Meteor 'bare' weight is 1077g. Well above stock (Which I think is more around 959g when mine was stock, or close to that), because of retracts and painting and then many coats of WBPU for a protective shell finish.

The Dynam Fan/Motor on 4S, as I had used for a short while initially, was pretty lack lustre. A move to 5S definitely sped thins up! To a 155Kph Top Speed area (RCspeedo'ed on a number of occasions).
Then I switched to a L2855-2300kv driven CS10, using the stock ESC still. By now I had added retracts, and later on painting, so overall it was worse than the Dynam Fan.Motor on 5S. But still a very nice sporty jet, probably doing 135kph to 140kph Top Speed area.

Testing showed that the L2855-2300kv CS10 is a near perfect combination in the stock Meteor.... and the inlet, exhaust, fan, totals add up to a very free flowing system - in-plane thrust results are not far off the bench maximums possible with this combo. Note - I also have the CS10 inlet lip on the fan in the Meteor, as it needs that 'bridge' to the internal ducting.

Tests and results next.....

....
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Old Dec 29, 2012, 10:34 PM
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Luckily I had done tests and recorded them right from the original build of my Meteor....
On the Dynam Fan/Motor on 4S and on 5S.... but not with larger, higher "capability" batteries also, unfortunately.

The stock Meteor on 4S, two batteries used, gave a pretty poorly 0.45:1 and 0.57:1 Thrust to Weight ratio!! No wonder it flies so 'average'!!
Moving to 5S raised that to 0.69:1 and 0.73:1, which at about 0.7:1 you start getting a jet that flies like a 'jet should'. For very zippy speeds you need more towards 1:1.

In the results table pic below you can see that the move to the L2855-2300kv CS10 has increased the Thrust to Weight up to 0.81:1 and 0.87:1. Now we are getting more towards good speed capabilities!
But note, these are on higher 'capability' batteries than the Dynam Fan/Motor was using with its 3000mAH sizes. The closest comparison (by numbers anyway) are the 3000 30C = 90A in the Dynam, and 4000 20C = 80A in the CS10. 0.73 versus 0.81... so the CS10 combo still won out.
I need to do a few additional tests using those prior 3000mAH batteries in the CS10 so that then there is a truly direct comparison to be seen.

With the larger batteries the weights are up, but the Thrust to Weight is still better.
Down the end of the results table you can see the Efficiency numbers, and the CS10 wins those too overall. Only the weak power of the 4S Dynam on a 3300 30C beats it, but of course that combo can only fly around like a slug anyway! hehe
Run the CS10 at lower throttle areas and its overall Efficiency will rise a bit too.

Another thing to be seen is how the L2855-2300kv CS10 loses efficiency once it goes over 1000W area. The 4000 40C, which could run it at 1100w, drops in efficiency. So that shows you don't really want to drive this motor over 1000W area.... for efficiency reasons, but as well as for lifespan reasons because L2855's don't like over 1000W - they are rated to 900W by specs and that seems about correct really.
But of course (??) you won't fly at WOT all flight, so you would generally operate more in the 800W or so region. With the occassional WOT burst to that 1000W/1100W area. So that is OK and all in all you are likely to run in the optimal efficiency area for most of the flying.
This will also keep the ESC Amps down to more in the 50A area or so... with those occassional bursts towards 60A area. (The stock ESC's max rating). Those Detrum ESC's are really good little varmints!! Just like the stock Dynam fan and motor are too really!
But the L2855-2300kv CS10 comes out the winner overall.... a perfect match, from pretty well the lowest budget combo possible! ($13 motor, $16 fan).

The Zippy Compact 5S 3700mAH 25C battery.....
This is the best battery to use for this combo ALMOST!!!
It is the lightest of the tested batteries.... it is just $34..... at "92A Capable" (3700 x 25C) it fits the "Use a battery at least 1.5x the needs in its capability".... it fits really well....
But a bunch of these Zippy Compacts have one issue!!! The imbeciles making them wired them up as if they are going to run 100Amps plus!! (which you shouldn't even ever do with them!). So they used 8 AWG leads out of the battery, and these are very hard to BEND into correct paths for most aircraft! They exit the battery at an angle, not parallel to it (like most batteries do) and 8AWG is so strong and stiff that if you bend it, the forces going back into the battery will snap off the battery tabs they are soldered onto!! I have wrecked two of those battery types having that occur. It is just so stupid to use such heavy gauge wire on them.... and to open them and change that is a major task!
For this test one I had cut them short, to 20mm approx, and moved down to 10AWG (or was it 12AWG??), but even that short stubby 8AWG length still makes it very hard to safely connect it up in the Meteor! You can just feel the stress going back into the battery - it is probably JUST passable.
So you really need to cut open and re-wire those Compacts, to erase the fair chance you will wreck it eventually - sooner or later!

Basically the 3700mAH Compact saves you 50g of weight over the equal performing Zippy 5S 4000mAH 20C (non-Compact) which costs $34 also.
So in the end this 4000mAH is the true winner, by a fraction in numbers (a bit higher Capacity also) - but by MILES due to the stupid Compact wiring issue!
A 3000 or 3300 30C will cost even more than that too. And in that lower capacity you need that higher C (30C).... so that just doesn't pay off in cost, unless you want your Meteor a bit lighter and thus a fraction more spritely - but it is not much of a weight saving really.

...
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