Giant Cod Edge Profile ARTF build blog (of sorts)

[Bob Moore]

It does look a bit like that, but at £13 I can  try manoevres that I wouldn't risk with one of my bigger more expensive IC models.  I've had great fun with it.  Just the thing for teaching your children to fly in the park too.   Check out the 15 reviews on GC. 4.87 score out of 5.

[Erfolg]

Bob

 

My calcs/measurements put the CG at 2.125" (53mm) from the LE. Yours is much further back, is it the 540 you have?

 

Taildragger

 

I think horrific is far to strong a description. Value for money is better.

 

When i compare the GC model with some similar models in the club, the material is much thinner. Yet the finish is far better, with the hard printed skin.

 

Compared with the models flown in the "Masters" videos, it is to heavily built, with solid wings etc.

 

It is the detail which makes the model to heavy, yet for beginners on a low budget, pretty damn good.

 

It is certainly not cutting edge technology, yet a better kit than many far more expensive kits. It is, what it is, a budget model for ordinary flyers.

[Bob Moore]

Hi Erfolg, yes it is a 540. Some of my calcs put the CoG quite a bit further forward, but as I said I was having to put almost full down elevator on to get level flight.  I found a graphical method on another thread which put it at 80mm and shifted my battery just about as far forward as it would go to achieve that.  It seemed pretty extreme to me, but I did it and it solved the down elevator problem and flew 100 % better. (My model is more than usual tail head as I have had to repair the elevator with more tape and a couple of cocktail sticks, plus reinforced the main wing to fusi join aft of the C o G.)

 

My other models had CoG given so this is the first time I 've had to experiment, plus this is pretty battered now!  All I can say is that's where it balances and it flies well. Rolls and flies inverted?  Why not compromise half way between the my 80mm and your calc?

[Erfolg]

Bob

 

My method is very simple in this instance.

 

The leading edge is straight, with all the taper on the TE.

 

At mid span the chord is 7" or 175mm. 30% is approx 50mm.

 

What I have omitted is the area of the side chines. have you taken these into account?

 

Erfolg

[Bob Moore]

I'm rather a beginner at working out this stuff and after looking at a few methods, I used the graphical method here  and used the mac from that.  I've probably done ir completely wrong, but it worked?  The projected line with three dots is my 80mm CoG?

 

I didn't take into account the side chines, but maybe I should have!  Seems to work anyway

 

Looking at it again here, I probably took completely the wrong line!!!

 

 

Edited By Bob Moore on 30/12/2010 22:53:34

[Erfolg]

Hi Bob

 

The graphical method/process you have used is in principal the same as the simple maths method I use. Both therefore should provide the same answer.

 

I t could be that a simple step has been omitted from the process you have used?

 

As shown the MAC should be circa 172mm, at mid span of 230mm.

 

This is the same as the calculated value

 

which is (root chord+tip chord)/2 , (230+115)/2 = 172mm at mid span 160/2 = 230mm.

 

I suspect this is where the differences lie. I have chosen to place (hypothetically) the CG at 30% of the MAC. Which then becomes (172/100)*30 = 52mm.

 

Which then made me think 80 is a lot different, what is it as a percentage of the chord?

 

So I rearranged the basic relationship to (80*100)/172 = 46%.

 

This value of 46% has caused me to suspect that you have place the CG on the 50% chord line of the MAC, omitting the the final step. It is obviously only my suspicion/idea.

 

I guess what matters is the model flies, and apparently well.

 

It would help me (Selfishly) if we can determine the differences on placing the CG..

 

Erfolg

 

I do realise that not all the brackets are necessary, but does help make it easier to see what I have done.

[Erfolg]

It is Fertig, Zuende or Finished!

 

The all up weight is 234g. That is with motor battery and servos etc.

 

I still could do with an little additional feedback on the CG,

 

I will post a picture, but it just looks the same as everyone else's. Not remarkable

[Stephen Jones]

Hi Erfolog ,

 

I`ll go in loft later and check where mine is although mine is not perfect .

[Erfolg]

Much appreciated Stephen

[Bob Moore]

That's amazingly light.  Where did you shed the weight I wonder? Mine's more like 375 gms (just a spring balance to weigh it? )  but it has had quite a bit of tape, thin ply and balsa added now.

 

What battery/ motor/ prop are you using? 

[Stephen Jones]

O M G

 

 

Just been in my loft and my GC Edge weights in at a whopping 410gramms , motor 2812 15t

33amp Esc , 3s 1300Ma battery , 2 x 9 Gram servos , 1 x 15 Gram servo, and some balsa to restrengthen and My CoG is 45mm from the Leading Edge .

 

So while i was in the loft i decided to get the un-built foam models down for comparison 

Just look at the Difference .

  

I think i Building the yak 860 next clear instructions plenty of carbon fibre , allthe hard wear you need and the control surfaces are cut at an angle ready for hinging .

Edited By Stephen Jones on 03/01/2011 22:11:19

[Erfolg]

There may be a number reasons for the big difference in weight.

 

The first i am using a A2204 1400kv motor, which weights 19g.

 

The second is I am using a 2s 500 lipo, forget the weight.

 

A third possible, is I am using CF to the elevator and Rudder, rather than extension leads, or wire push rod.

 

A forth possible, I have not used the supplied tape, where hinging is required i have used Blenderm. The CF is held in place using UHU POR.

 

Further weight could, maybe should, have been saved by substituting the wire UC for CF.

 

I have also avoided to a large extent the ply supplied, using 1/32 for the motor.

 

I have added additional weight with the depron webs front to back , underneath and short webs on the top, where you have used balsa, I think?

 

All servos are 5g, which i guess we all used

[Stephen Jones]

Please Let us know how it fly`s .

That is how i have considered building the GC cap 232 with additional strength added to the fuselage and wings by supporting them by bracing fishing line between them .     

[Erfolg]

I will certainly let you know how my model flies or does not.

 

I am waiting for some good weather, to give it a try. Does it always seem the minute you are ready, the weather isn't. After many weeks of sitting in a low, with no worth while wind, suddenly fronts start coming in, one after another.

 

The information with respect to the 42mm is vary reassuring. My own assessment indicates 53 mm. Bobs being at 80. It suggests a bit of tolerance in CG range. If it would benefit from moving forward this will require a little work, as most things are pretty far forward.

 

 

 

[Bob Moore]

The fishing line might be useful, but I still think you'll need to stiffen the fusi longitudinally as it's very twisty and flexible. Trouble with the fishing line may be snagging it when you land and ripping out whatever you attached the ends too?

 

Yes the weather isn't playing ball lately. You certainly need very little or zero wind to test fly as it's picked up by the slightest breeze and is quite slow.  Keep it up wind!

Edited By Bob Moore on 05/01/2011 13:28:32

Edited By Bob Moore on 05/01/2011 13:44:02

[Erfolg]

Fishing line is the right idea, probably not the best solution.

 

If you look at many of the models shown on the Masters Video, or FD Ballerina or the Stunt Monkey, all have bracing using 1.5mm rod, hot glued.

 

With respect to longitudinal twisting, this seems to be additional addressed by longitudinal Depron fillets and or having a "fish" shaped fuz, where there is a substantial depth at the rear. The rear having warren truss type CF rod reinforcement.

[richard hargreaves]

Hi all- first post for me.

have built the edge 540 as cheap as possible and thrown up a very basic vid of my poor flying on youtube .

Need a cameraman that doesnt shiver at 2 deg c and a half decent camera really.

My flying experience is many sim hours last winter (prolly close to 100hrs) followed by my first plane which was a 2nd hand well abused gws spitfire(now gone to the plane yard in the sky)-also have a funcub and a gws fw190(epo) making around 300w ish.

Total real world flying experience of between 3 and 4 hrs so bare this in mind if you give the vid a look.

The edge is using 4 emax servos as recommended on the cod website plus a towerpro bell motor and 30a esc with a 10x 3.8 gws prop. Cog is around 80mm from L.E. of wing

Peak power around 195-200w powered by tipple 5c 1000mah batts flying weight is about 350-360g.I've added about a tenners worth of carbon rod and strip to strengthen it in order to suffer my ham fisted abilities.

video is here

http://www.youtube.com/watch?v=Ewd-5OgRI10

cheers richie

[Bob Moore]

I flew mine again today, it flies well, but I think you have more pulling power than I do. I'm drawing about 9 amps max, so I reckon 70 watts. What Kv motor is that and how many cells please. (I did try Googling it!) Prop I used today was a High speed APC Style propeller 1005E / E10x5E. Didn't find much difference to my SF 3D propeller 9x6 SF.

Had better luck with that than I did with a second maiden of my number two Wot 4. Brand new Irvine 40 engine . Ran beautifully on the ground and for a few minutes in the sky. Climbing almost vertically, but 3 dead sticks. The last I didn't get back to the strip. Fortunately didn't land on the tarmac lane alongside but cliiped a hedge and into the field next door. Fusilage pretty badly damaged but fixable. I can see why people are switching to leccy.

First maiden with the Wot4 , with a different engine, I had similar results. 3 dead sticks and the last ripped the u/c off (almost in the same field alongside ours.)

[Erfolg]

Hmmm

I do not think I can measure my amps pulled, due to the little plugs and sockets and no adapter.

I am waiting for warmer weather to try my model.

Must take a photo, for the record.

Awwwwwwwwwwwwww the weather is so cold, what happened to global warming.

[richard hargreaves]

The tower pro motor is a 2409 18 delta running at 1000kv-the 200w is a static figure which I'm guessing unloads to something close to 180w airbourne(prop is the gws slo fly btw).

The data sheet (www.hobbyking.com/hobbyking/store/tp_motor.html) gives a 60second max output of 180w but much more than 15 seconds would see it so high vertically that I doubt I would be able to see the thing and flat out level flight just looks wrong in this model in my opinion.

It flies fine on 1/3 to 1/2 throttle and the 7 minute video took less than 600 mah out of the battery.

Wind speed I'm guessing at around 5-8 mph so a slightly heftier breeze shouldnt provide any issues either .

In addition to my flying fleet listed in my first post I also have an FMS P51 1400mm version with flaps and retracts which I am yet to build untill I am happy enough with my skill levels that I wont reduce it to scrap on my first flight, although if someone twisted my arm hard enough I might sell it on in order to finance a pair of smaller birds which would be more suited to my flying field which is only 120 m wide but about 500m long and tree lined at the edges ( 51 31 04 n 3 29 48 w on google earth). As its only 400 yds or so from my house its rather easy for me to sneak in a quick battery or 2 weather allowing.

cheers richie

[Bob Moore]

My weight is just a little more than yours, but not a lot. My motor is a 1600 kV and I use 2s 1000mA. I'm afraid I didn't understand whether you are on more than 2 cells? Mine needs a good half throttle for level flight and full on gives a pretty slow climb. Flies well enough though and as I've said before, is great fun. Allows me to try things I wouldn't risk on a bigger more expensive model.

Interesting that your CoG is exactly the same as mine. Erfolg calculated it quite a way further forward.

[Erfolg]

The CG issue is interesting, beyond academic.

Stephen has the CG the furthest forward at 45mm, his has flown, successfully if my memory serves me well. Then I have the CG at 50mm but not flown. These are in the 25-30% chord position

Both Richard and Bob have the CG at 75mm which is 50% chord, which normally would not be considered viable for RC.

I guess that it could be the flat plate airfoil that makes the big difference. I will post a general post to see if those that fly indoor models can shed some light on why, the unstable appears to be stable.

[richard hargreaves]

Sorry should have said batts are 3s not 2s and only £7.75 from giant cod here http://www.giantcod.co.uk/loong-tipple-1000-3s1p-2030c-lipo-battery-p-404434.html .

Could the variation in cog be down to the size of the ailerons making a bigger wing in level flight?

As it is mine may be a tiny bit tail heavy I suppose but certainly not bad enough to make it hard to fly given how inexperienced a flyer I am.

It definately makes it easy to prop hang although the poor quality video makes it tricky to see , however I aquired a decentish video camera today so will try to get some better footage up asap , work/weather conditions allowing.

cheers richie

[Erfolg]

As promised pictures of my finished build.

Nothing remarkable. Just two changes from the instructions, first the spar is inset, two keel reinforcements, which are easier to see on the underside.

Possibly the other change is the use of Blenderm to save weight on hinging and some reinforcements.

[Bob Moore]

Good luck with the maiden. I'll be interested to hear how the CoG worked out?