[Claudius]

once you go below 3.7v per cell it will drain quickly .

3.7V/cell unloaded is well on the way to a empty cell.

but as claudio suggest cells can sustain 3.8 volts under load for some time .

I probably mumbled "unloaded", not "under load" Because the voltage of a LiPo cell is quite flat over a good portion of the state of charge, a reading of around 3.8V/cell after flight (i.e. unloaded) could be 20% remaining, or 50% remaining. A cell checker can only do so much, hence the suggestion to check the mAh returned to the pack on charge.

Wayne, if you do a Google Image search for "lipo voltage chart", you'll find any number of graphs which show an average *loaded* cell voltage of between 3.5-3.7V/cell, depending on the C rate of discharge.

3.3V per cell is much too low for a LiPo, and would be more appropriate for an LiFePO4 cell at a low C rate.

[Flying fisho]

I think I need an asprin

[wingtipper]

please understand , i was not suggesting that 3.35 volts is ok . i was trying to suggest that 3.7 was on the limit and pushing it , sorry for any confusion. i like to bring mine down with 3.8 or more unloaded .
i understand what wayne was asking , and when my batteries are around 3.8 no load per cell , under load they are around 3.7 as tested( EDF, 40-50C) ,however as claudio says they can still have 50% left or 20% left time plays a major factor .

[gbanger]

My appologies if anyone thought I was having a go at them. That was not my intention.
I was just trying to get a point accross.
I check my batteries as soon as I land with a good quality cell checker and never let my batteries get below 3.8 volts and about 40% change unloaded. They just last a heap longer that way.

[secant0give]

My appologies if anyone thought I was having a go at them. That was not my intention.
I was just trying to get a point accross.
I check my batteries as soon as I land with a good quality cell checker and never let my batteries get below 3.8 volts and about 40% change unloaded. They just last a heap longer that way.

I do the same with most of my packs, But I have had some set aside for extreeme punishment and Yes you guessed it they get sad pretty quickly !! Fly them hard and they dies fast !!

[Flying fisho]

Just bought a new Zlin (Model flight boxing day special) http://www.modelflight.com.au/products/H...07-10.html
According to Ecalc am looking at a power train - Turnigy G60 400kv, Turnigy 60amp Plush ESC & a 14 x 8 prop. Is this an overkill ? Not sure which servo's tho

[wingtipper]

Just bought a new Zlin (Model flight boxing day special) http://www.modelflight.com.au/products/H...07-10.html
According to Ecalc am looking at a power train - Turnigy G60 400kv, Turnigy 60amp Plush ESC & a 14 x 8 prop. Is this an overkill ? Not sure which servo's tho

hi wayne . i use in my mx2 a turnigy 50 50 580 kv 2000 watt motor on 6s 3000mah 20 c batteries it drives a 15x8 lightwood prop and has about 5+ kg of thrust . http://www.hobbyking.com/hobbyking/store...duct=22035 THE MX2 WIEGHS 2.2KG AND HAS 57 INCH WINGSPAN . same size plane as your ZLIN.
i would suggest an 85 amp esc or more for this type of plane as it will be pulling some load if your hovering and verticle climbing etc you would be pulling about 95 amps spike and 2100 watts on 6s .
or put the 15x6 on , just as good and about 85 amps spike and 1900 watts . great motor with heaps of grunt .

[secant0give]

Just bought a new Zlin (Model flight boxing day special) http://www.modelflight.com.au/products/H...07-10.html
According to Ecalc am looking at a power train - Turnigy G60 400kv, Turnigy 60amp Plush ESC & a 14 x 8 prop. Is this an overkill ? Not sure which servo's tho

It sounds similar in size to my Edge 540. It's got a very similar power train to Wingtipper's MX2. I reckon that's a pretty nice way to go.

[Flying fisho]

This plane has largish control surfaces pushing a 2.35kg beast thru the air aerobaticly at about 100 clicks. I would expect the servo's to require a bit of grunt. Any suggestions without doubling the price of the plane?

[Flying fisho]

Looks like I will have to wait for Zlin to arrive, there is no mention of servo size needed. I have "park size" (33mm x 19mm) servo's in my Eratix & Pulse but I imagine as the planes grow in size, so might the servo size. I am aware that servo torque needs differ not just with a plane's weight but also with its speed & control surface size. I imagine 3 - 5kg of torque would suffice & .1 to .15 sec speed. Not sure about digital v analog

[Flying fisho]

Hello, me again
My troubled E-flite Pulse is almost ready to fly again, all that I have left to do is attach the coveding film that I have purchased. Have asked at all the hobby shops I know but none have the iron I need. I also lack the experience, confidence & knowledge. If I could have somebody's assistance, I would be very appreciative.

[gbanger]

If any club members knows Steven Chins contact details please pass this link onto him ASAP.
The receivers alone are worth almost $700.

http://www.rctrader.com/category/359/Tra...eiver.html.

Shit... if I had the cash laying around I would buy this just for the recievers... not to mention that you will look far and wide to find a better radio!!!
Gazz

[Flying fisho]

Clicked on the link & got redirected to RC trader home page after message "Sorry the page you have requested no loger exists" appeared. Looks like too late & I only have his email address anyway.
His name appears as "Build 'em crash 'em" on the members list.

[gbanger]

It still exists you just cant cut and paste that link.
Try this one, it works for me.

http://www.rctrader.com/category/359/Tra...eiver.html
Gazz

[wingtipper]

JEEZ im glad i boght the DX8 otherwise i wouldnt be able to resist that package and hit the buy now button $$ that i just dont have at the moment .
who ever gets that one will be a happy chappy .

[smuzz]

This is more like a reference, than a Q and A post - but anyway ...

I've been meaning to put this up for about a year, and have finally got around to it. For those that haven't seen it, it's a very good motor test database. It's in French, but the numbers are the important things anyway. If you select the Union Jack icon up the top-left for an English translation, it will parse the page through Google Translate, which works well enough. It's a very comprehensive collection of data, quite useful - just remember that Europeans will use a comma ',' where we would use a decimal point '.' and vice-versa so if you see 3,400 it means 3.400 not three-thousand-four-hundred.

http://www.bungymania.com/bmdb.php

There are also other reference pages there focusing on servos, and on kits. What I find most useful, is that it's not all brand-name premier stuff which they have test data on (yes, they do Hyperion, AXI and such) but they've also got heaps of data on the Hextronic and Turnigy stuff and that's more directly useful to most of us, because the reviews that are available on HK's web-site are often dubious in their technical content.

[BenR]

Question for repairs......

I have a UM plane that has a challenge to repair. Its a biplane (UMX Beast) and the upper wing is held to the fuse by a piece of moulded plastic and glue. That plastic is fairly thin, and there should be 2 straight parts that come out between the parts moulded for the fuse and the wing on each side. On one side, one of these pieces has bent, and needs straightening and possible reinforcing. I suspect I can use something like a hot glue gun tip to soften the plastic enough to make it pliable for reshaping, but suggestions welcome for better ways to shape/any ways to reinforce.

[Raptorfly]

Question for repairs......

I have a UM plane that has a challenge to repair. Its a biplane (UMX Beast) and the upper wing is held to the fuse by a piece of moulded plastic and glue. That plastic is fairly thin, and there should be 2 straight parts that come out between the parts moulded for the fuse and the wing on each side. On one side, one of these pieces has bent, and needs straightening and possible reinforcing. I suspect I can use something like a hot glue gun tip to soften the plastic enough to make it pliable for reshaping, but suggestions welcome for better ways to shape/any ways to reinforce.

Hi Ben

Use a hair dryer to soften teh plastic. Use toothpicks hotglued to the underside of the plastic to re-inforce them.

Good luck

[BenR]

Use a hair dryer to soften teh plastic. Use toothpicks hotglued to the underside of the plastic to re-inforce them.

For the reinforcing, should I reinforce only the 1 plastic area that is out of shape, or should I take the opportunity to reinforce all 4?


And on a completely different question, I have been flying something where it wants to go nose up every time I put on the power - which I am fairly sure is angle of the motor (it glides at essentially perfectly level). However, most of the times I have flown it I would have called strong winds relative to the size of the model. Is it best to wait until I test it on a still day and then test/adjust the plane for motor angle?

[Raptorfly]

Do all four if you think it will help.

Nose up on power could be motor angle, it also could be the thrust line and or the trailing surfaces... best tested on a calm day and then eleminate one possibility at a time.

[smuzz]

And on a completely different question, I have been flying something where it wants to go nose up every time I put on the power - which I am fairly sure is angle of the motor (it glides at essentially perfectly level). However, most of the times I have flown it I would have called strong winds relative to the size of the model. Is it best to wait until I test it on a still day and then test/adjust the plane for motor angle?

Can't help you with the hairdryer stuff at all, but to other matters ...

1. The issue you're observing above does sound like a thrust-line problem, since you mention that with no power it glides in a well-behaved way. It's also possible (but much less likely) that the tailplane has a negative incidence too, if it's received a knock at some point - in a slow glide it might not have a noticeable effect, but be apparent more readily when you apply a lot of power and get the prop-wash back over the tail. Testing in perfectly calm conditions is the best idea, particularly if it's a very small (indoor?) model.

2. To a question you posted a while back and I think nobody answered - the CASA regulations apply to model aircraft in the take-off weight range of 100g to 150kg and so your ultra-micro at about 30 grams isn't the subject of any operational rules or procedures. It's unlikely that you'd cause any catastrophic outcomes with it, but I understand your willingness to double-check. Clearly it would be uncomfortable for everyone concerned if for argument's sake, it hit someone in the eye at full-bore - but we've been living with that sort of threat to civilisation since the very first small rubber-band powered free-flight plane ever took to the air. If you exercise "reasonable caution" in terms of any objective assessment, you'll be fine.

[secant0give]

And on a completely different question, I have been flying something where it wants to go nose up every time I put on the power - which I am fairly sure is angle of the motor (it glides at essentially perfectly level). However, most of the times I have flown it I would have called strong winds relative to the size of the model. Is it best to wait until I test it on a still day and then test/adjust the plane for motor angle?

If the wing section is quite cambered (Has much more curve on the top than on the bottom or is flat on the bottom and curved on the top) then the faster it flies the more it will want to climb.

You can counter this by angeling the motor down if it's a tractor or up if it's a pusher, or by adding some small ammount of down elevator mixed in with throttle. Some combination of both might well be the most helpfull for a zoomy wing section.

[wingtipper]

hi guys . i need to milk your flying skills .
I have a rebel 70 , EDF. which is similar to a HABU 2 , it has a tri wheel landing gear setup with a nose wheel . IT flies great and is very slightly setup just on nose heavy for flying .
when i land , i have found it needs a bit of speed on throttle otherwise it will tip the nose on touchdown stall .
landing just of idle it has avery low sink rate , when it touches down i havent been able to master a touchdown without bouncing , no damage occurs , but the model is so light i dont know how to avoid this , if i give it down elevator it might tip the nose and cart wheel .
its ok i can fly it no worries , but is there any tricks to stop the bounce on touchdown . ???

---

^^^^^ "flaps" . this is my other personality answering !! LOL .

[secant0give]

Usually it's too much vertical speed that makes planes bounce on landing
You could try flying in all the way and just greasing it onto the strip.

[gbanger]

I'd agree with Jason on that one. I would suggest that your approach is either too fast or too slow, and you closing rate on the grond is excessive.
You need to work on getting that feather just right, an approach with a reduced angle from a little further out is a good place to start.

[wingtipper]

Yeah probably coming in a little slow guys , thanks . thinking about it ; it's lift off speed is pretty fast .

[secant0give]

landing is all in the approach. If the approach isn't right then it's not going to end well!!
I allways say if the approach isn't comfortable then go around and have another go.
For some reason, with most new RC Pilots there is this compelling urge to get the model on the ground ASAP once the decision to land has been made. In general this is a mistake, one should allways land with the direct intention of going around if the approach isn't just right.

If the approach isn't ligned up spot on then corrections will have to be made close to the ground and this removes the pilots focus from concentrating on maintaining the sink rake, the air speed, the elevator and throttle settings. To land these have all got to be right and this needs to be set up a fair way out. You cant expect to keep all that together for a nice decent if your moving the ailerons and rudder about to correct a badly aligned approach. You may get away with it if the plane is a very forgiving one but it's a bad habbit and it will cost an airframe sooner or later.

Another thing I see a lot of pilots do is flair way too high. They come in from a nicely aligned approach with about the correct speed looking great and then when they are 6 or 8ft off the ground they flair the model, so it slows up and drops like a stone to the ground
The place to flair is 6-8 inches off the the ground not 6 to 8 ft. This seems like another barrier that takes a while to break through. What they are doing wrong is trying to slow the plane up using elevator. This is no good because what happens is, speed gets traded for height then the plane stalls way off the ground, drops like a stone and the under carrage gets damaged or worse.

The way to bring a plane in is, firstly get it ligned up a long way out!!
Then get it in an attitude where it will fly slow. This means holding a little elevator so the plane will fly slow but not enough elevator to make it stall.
Hold this attitude all the way from way out there to 6 inches off the ground!!

The plane will start comming down because it's slowing up, you are holding enough elevator so that if you open the throttle it will climb but not enough to make it stall. This is a key point, find that elevator setting early and maintain that elevator setting don't change it!!

Watch the model's verticle speed and make corrections with the throttle only. What you are doing is controlling the rate of decent with the motor while holding a constant angle of attack on the wing using the elevator.

Do not use elevator to slow up, land longer or if your too fast, go around.
It pays big divedends to do heaps of practice approaches, landings are a compulsory manouver after all

[wingtipper]

well my experience with this plane with 4 landings , ( you saw the 1st one ) and it tipped over nose 1st .
the 2nd was fast and it bounced 3 times and the end of the runnway long grass captured it nicely . the 3rd was very slow and it bounced once and stopped without run on and tipped over . the 4th was with a long long low approach on light throttle and it touched down lifted up again 3 times as in a very light flare , each time i had to touch throttle as it wouldve stalled , this glided the plane for a good 5 metres between bounces and finally the long grass at the end of the runway caught it nicely . .
i'm talking coming in striaght , just above the weeds , just above throttle and then running off the other end of the runway . it only weighs about 1050g with battery , probably it is the grass friction on touchdown .
never the less it flew quite well and i think is a good beginner edf . although the stinger had a more direct glide and weighted better . miss the panther

[robair]

Gday All

Anyone can fly a plane, landing is a different matter entirely.
Landing slow is deadly, landing fast can be problematic however not necessarily a deal breaker in model flying form.
Provided that you have a good approach happening set up your flare so it's concluded few inches above the ground and then try to fly the aircraft to the end of the runway with no/ low throttle, as soon as you drop below stall speed your plane will quite literally land itself at a low speed. If you are too fast the end of the runway will loom and a go around is the best option.

Always Remember - A GOOD APPROACH LEADS TO A GOOD LANDING, this is a non negotiable concept. If your approach looks crap your landing will also likely be crap.

Cheers
Rob B

[BenR]

(Another repair question I know.....)

How do I go about reattaching a rudder that has come off completely? The rudder was held to the main plane by some paper tape which is between 2 sheets of depron - however that has torn completely. Am I right to go about taking the rudder off the control horn (which is the only thing holding it on), use tape on both sides of the rudder to reattach to the tail, making sure that the 2 pieces of tape touch in the middle, then reattach and adjust the control linkage?