1. Parramatta Radio Control Aircraft Club
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  Phoenix RC Flight Simulator

Posted by: smuzz
21-02-2011, 12:17 AM
Forum: General
- Replies (20)

A couple of months ago, Owen was talking to Gazz about flight simulators - Owen learned to fly pretty well using FMS (http://n.ethz.ch/student/mmoeller/fms/index_e.html) but for an industrial-strength simulator, Gazz recommended Phoenix RC.

Having purchased a copy of Phoenix RC a month or so ago, I can only reinforce everything positive thing Gary described about it. I got a copy from a local supplier, Brooknet (http://www.brooknet.net.au/Phxshp.html) and it arrived within a couple of days. Been really enjoying using it - time will tell whether it makes a difference to the skills levels, but it works seamlessly with Spektrum transmitter gear and is great fun.

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  Spectrum DSMX

Posted by: gbanger
10-02-2011, 04:39 PM
Forum: General
- Replies (5)

Spectrum have bitten the bullet and realized that they needed band hopping technology to stay in the game.
Here are 2 links to the release of of this (new) technology.

http://www.youtube.com/watch?v=iGYpnvHzod4&feature=fvwk

http://www.youtube.com/watch?v=iTS_iUwNd...ata_player

Gazz

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  Tower Hobbies Group Order?

Posted by: kizza42
08-02-2011, 08:59 AM
Forum: General
- Replies (8)

G'day,
Just looking for EOI's in a Tower Hobbies group order. Darren has offered the use of his account which gives some nice savings the more we order.

I'll be grabbing a CC esc and some micro balloons etc.

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  Heli Set-ups

Posted by: Skidz
07-02-2011, 07:40 PM
Forum: General
- Replies (1)

Given there were lots of questions on heli set-ups and that our club is electric only, I though I would post some excellent information for the heli guys on setting up throttle and pitch curves and the theory behind it.

The author is "Martin" from SSSFA who is widely acknolwedged as one of the most experienced electric heli pilots around.The original post came from www.rcrotorz.com.au which is a broad based heli forum. Martin has many technical posts on this forum and I would encourage heli pilots to take a look at his contributions.

http://www.rcrotorz.com.au/showthread.ph...ric-Heli-s

Throttle Curves for Electric Heli's

Electric motors work differently to nitro motors,
as such we use very different throttle curves
and slightly different operating procedures


What is different?
Nitro engines will over rev at high throttle settings and under no load
Electric motors don't do this - their speed is always exactly relative to the voltage they see
(Your TX throttle curve and the ESC control the voltage delivered to the motor)

Nitro engines will decrease in RPM when a load is applied
Electric motors don't do this, they just draw more current
(When a lot of current is drawn the battery voltage will drop a little, so will the RPM)

These two nitro characteristics are why we need a throttle curve (and ideally a governor),
to try and keep the headspeed constant

These two electric characteristics explain why we can use a flat throttle curve to get a constant headspeed
and even run an electric motor on a 100% flat throttle curve with no risk of over speeding
(A flat throttle curve means same throttle position across the entire curve, e.g. 100%, 100%, 100%, 100%, 100%)


Why is a constant headspeed an important goal?
Because the collective (lift), aileron and elevator all respond differently with respect to RPM
At low RPM they are weak, slow and mushy
At high RPM they are strong, quick and crisp

When learning to fly you notice this most in the collective
Your collective reflexes are not yet developed
You take off and find that the heli rises quickly at high collective stick positions
But when you drop the collective stick, the heli comes down very quickly indeed,
yet the heli is slow to arrest this decent if you let the headspeed drop

This is even worse on a windy day
Wind gives lift, a gust of wind and the heli climbs suddenly [uncommanded]
You need to use much more negative collective that you would normally to descend,
and if you're using a throttle curve, this will slow the headspeed badly

The combination of a changing headspeed and changing blade pitch
creates a lot of possible reaction speeds that you need to contend with - it's hard work

Even expert pilots are seeking a constant headspeed
They way they quickly trash around the sky,
they are expecting the heli to respond in a certain manner and speed to each stick input
It's a lot harder to time these moves correctly if the headspeed and reactions are changing a lot
(and when you're doing this on the deck, timing and response are vital)


Modern ESC's
These days, most ESC's have a soft start facility, it's vital
Electric motors can change speeds very quickly indeed
Without a soft start we risk stripping the main gear during spool up
(This may be another reason to not use a throttle curve!)

Make sure your ESC is set to heli mode (mainly turns the brake off) and enable the soft start

If you are using a CastleCreations ESC there is a lot of information for you here (PDF's and Videos):
http://www.rcrotorz.com.au/showthrea...ghlight=castle

You need to run the ESC at 75% throttle or higher (Kontronic ESC's can run lower)
At lower throttle settings, the switching components in the ESC get too hot and can burn out
This is a factor we take into account when selecting the number of cells, motor KV and gearing


Electric Throttle Curves
Due to the way electric motors work (constant speed at a steady voltage)
we tend to run flat throttle curves, same value right across the curve.
This delivers a steady voltage to the electric motor and gives us a steady headspeed

So what do we want to get out of our various throttle curves?

The normal mode throttle curve is normally targeted at getting the heli through the spool up procedure
and gives us a usable but calmly behaved heli
When we encounter problems with the heli in the air,
we will either want to take the heat out of the heli and drop back to a calm normal mode
or in more serious situations we will go into hold mode (crashing with power off creates much less damage!)

So for example, normal mode: 0% 75% 75% 75% 75%

The stunt1 or idle1 throttle curve for beginners would typically be the same as normal mode
without the 0% setting that we use when spooling up and down
This enables us to use full negative pitch and still be fully powered

For example, Stunt1: 75% 75% 75% 75% 75%

The stunt2 or idle2 throttle curve may be used to give a quicker headspeed for hot dogging around

For example, Stunt2: 90% 90% 90% 90% 90% (but you can use 100% flat if you want)

The specific setting values will depend on your setup and the headspeeds you get - adjust as desired


Spool up & down procedures
The ESC soft start enables us to use a different spool up procedure,
and supports the use of our flat normal mode throttle curve.

We simply smoothly raise the collective stick to zero degrees (normally middle stick position) in one single motion
The heli will start to spool up slowly thanks to the ESC soft start
Once the headspeed is fully spooled up (~5 seconds) we then raise the collective further and take off

After landing in normal mode you smoothly drop the collective stick to the bottom,
the power to the motor will be cut, the heli will spool down nicely
Also note normal mode pitch suggestion in next section


Pitch Curves
If you read older RC heli guides, they say beginners should learn to hover without any negative pitch
That was fine back in those days, but these days heli's are both lighter and have more lift
I've seen numerous beginners struggling to bring a heli down on a windy day
I tend to start beginners off with these 3D curves (hovering at 75% stick)
(the values are pitch degrees - not TX point values)

Normal: -5 -2.5 0 +5 +10
Stunt1: -5 -2.5 0 +5 +10 (When learning to hover)
Stunt1: -10 -5 0 +5 +10 (When learning basic 3D)
Stunt2: -10 -5 0 +5 +10 (Full linear 3D setup)
Hold: -5 -2.5 0 +5 +10

This enables you to bring the heli down on a windy day

This means when you spool down in normal mode,
the heli does not push hard into the ground
(-10 degrees is a lot - it can squash skids on small helis, you'll snag the tail)

The hold curve is designed to avoid you grabbing too much negative
Just aim for 1/4 stick and guide it in

Normal, Stunt1 and hold all feel the same (especially when you loose power!)

When you're much more advanced you will change these - but that's another story/article


Caution

When running a flat 100% throttle curve,
check your headspeed to ensure it's safe!

Generally smaller heli's can use faster headspeeds
due to shorter blades and associated forces

Here are some rough guidelines for beginners:
325mm blades ~ 2750 rpm
425mm blades ~ 2600 rpm
500mm blades ~ ???? rpm
550mm blades ~ 2100 rpm
600mm blades ~ 2000 rpm
700mm blades ~ 1900 rpm

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  Build log: The Blu-Baby

Posted by: smuzz
04-02-2011, 06:13 PM
Forum: General
- Replies (13)

JohnP was I think, the first in our club to discover the Blu-Baby Trainer (http://www.rcgroups.com/forums/showthread.php?t=681556).

My instructor says that I should have another plane in the hangar to fly solo with and I think the Blu-Baby might be the ticket. John's example looked good to me and I thought I might get one together. I haven't worked with depron before so it seemed like an opportunity to put other things aside and get started.

The RCGroups Blu-Baby thread is over a thousand pages long, so I read a few of them and made a couple of decisions ...
- Will build the 42" version because it suits a spare powertrain I already have, and the extra size might help me keep it sighted.
- Also, must build the aileron version because I think I'd be lost without ailerons.

Printed out the plan sheets and stuck them all together. The first task was cutting the so-called monobloc. This is normally made from pink/blue foam or even laminates of depron up to the required thickness. I had a large block of balsa lying around unused and it was about the right thickness, so used it instead. Having access to a band-saw made this job easy, otherwise it would have been difficult to cut by hand and keep square.

   

While the band-saw was handy, cut a bunch of styrofoam semi ribs for the wings. These are nice and wide and will go from the leading edge back to the wooden spar. Made from off-cuts of foam packing.

   

Now cut all the depron parts (well, most of them anyway) from 6mm depron. This is easy as long as the scalpel blade is very sharp and gives a satisfying but false sense of significant progress, compared to building a model up from balsa.

   

OK, that's it for one session - need to have a couple of beers and think about options before lurching forward.

OK, last post work done over a week ago, I'm just catching up with my progress here.

The wing was next to receive treatment. The original version called for a rolled, undercambered depron structure but reading through the posts indicates that it tended to flex too much. An alternative was a Kline-Fogelman aerofoil but I decided to go for the built-up sport wing just for fun. Started off with some balsa leading edge stock, chamfered the depron to butt against it and stuck the semi-ribs on. I was using UHU-Por as the glue because I hadn't tried it before and it's apparently "the go" for depron.

       

Next was to get the timber spars in place, would have used some CF box-section instead if I'd had some at hand - never mind, wood would do! Some little recessed boxes in the undersides of the wings for the aileron servos to come later and some depron semi-ribs between the spar and the trailing edge. The aerofoil is a flat-bottomed section, but I simply sketched it out by hand - it doesn't represent any properly designed NACA or other design.

   

The upper surfaces were then covered with 2mm depron, after having ensured some pieces of cotton were placed inside the wing so that I could pull the servo leads and extensions through later. The next photograph shows the wing root with the spruce spar and guide ready for the two ply dihedral braces to be glued in.

   

I attended to aileron hinges before cladding the top surface of the wing - this was done by gluing hinges to the top the 6mm depron wing undersurface and then sandwiching them beneath the 2mm top surface. This saves having to cut slots afterwards and guarantees that they're solidly glued in place.

   

A slight departure from the plan was next (yes, I'll take full responsibility and I know I might regret it). The cavity for the battery-bay in the underside of the mono-block was too small for the 2200 mAh batteries I want to go in there (so I don't have to buy another battery size variation). I extended the size of the bay towards the front. This meant that the standard undercarriage mounting position was now cut away though. It would be a good idea to keep the undercarriage legs in the same position, so some holes were bored into the block above the battery-bay and grooves cut into the block so that legs could be inserted from each side and set into the grooves with a forward rake.

       

Some extra grunting and farting later, we have bent undercarriage legs in the correct position and once set with expoxy they should be strong enough to deal with my clumsy landings.

   

Right now, it's beer-o'clock again so more to come later ...

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  Wanted AGP ATI Card.

Posted by: srl
31-01-2011, 09:43 PM
Forum: For Sale
- Replies (1)

I'm Just going over my CNC mill and my reading up tells me that I need one for better parallel port performance.
I'm a Nvida Man.
Doesn't mater how old it is.

srl        

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  HK Spitfire Supermarine 1.4M XL

Posted by: Omarko
27-01-2011, 05:32 PM
Forum: For Sale
- Replies (8)

hey guys

I have a brand new unused HK Spitfire Supermarine XL for sale. Still in orig box, never opened.

Anyone interested? If yes, make an offer (they are $159+ post new)

A

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  Lipo's anyone??

Posted by: SydRob
17-01-2011, 08:09 PM
Forum: For Sale
- Replies (7)

Hi Guys,

Been away a little waiting for my membership, to hard to go to field and not be able to fly. Anyway, got a few high discharge LIPO I bought after some late-night, Jim Beam fueled Hobby-king sessions, that I don't really need.

Will post pics later -

Zippy 3S 2200mah, 30C. XT60 Connector.
Rhino 3S 1350mah, 30C. XT60 Connector.

Offer me a bit less than HK prices and their yours. Unused. Just charged once. (( Please balance and check b4 use - anything wrong money back of course ))

Can't wait to get into it this year!! Happy New Year to all the crew. Thumbup

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  Annoying Stuff

Posted by: Drew
15-01-2011, 10:19 PM
Forum: General
- Replies (4)

Two weeks ago, I went to take off an discovered a total lack of power from my motor. It sounded more like a sewing machine than a model aircraft motor.
I tested a couple of fresh packs and not difference.
I deduced that it was probably speedy trouble as I had been pushing the 55A Scorpion speedy. I had been using 20c 2200Mah batteries so only had 44A - well under the speedy headroom. However, about 4 flights has been on 6S (serialing two 3S packs) and when I inspected the speedy, it is labelled as rating to 4S.

Prior to this, I had noticed possible sluggish response and figured old batteries and a need to switch to 4S operations for a power/ speed boost.

I've just finished soldering up and testing a brand new Plush 60 from Rob and got similar results!!! On the amp meter, it was barely drawing 10A at full throttle.




I did recell changing the prop recently 'coz I figured that mine was starting to look a little banged up. It was the same size, pitch and manufacturer. Anyhow, I swapped back after the poor result on the plush and nearly hamstrung myself (I was standing with my feet in fromt of the slabiliser to stop the plane running away)!!! A full 46A coming from the battery and plenty of thrust.

I think I have probably hurt my scorpion speedy but the real issue might have been an unbalanced ot uncentred prop Frown. To prove this, I need to unsolder the bullet connectors and resolder them to the scorpion. Too much trouble right now but I may do it later for academic interest.

The good news is that it has proven that my motor is fine. Smile

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  [split] New Addition to the hanger.

Posted by: gbanger
13-01-2011, 03:53 PM
Forum: General
- Replies (1)

Just weighed the PC9 for you Steve.

Take off weight is 2790 grams with a Turnigy 5S 4000 30-40C battery.

Am running this Turnigy 85 amp ESC with built in 5 amp BEC that also comes with an On/Off switch
http://www.hobbyking.com/hobbyking/store...duct=10331

Cheers Gazz

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  1. Parramatta Radio Control Aircraft Club