Giant Cod Edge Profile ARTF build blog (of sorts)

[richard hargreaves]

Posted by Erfolg on 20/01/2011 13:53:20:

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.

Might just be a plane thats not that cog sensitive-from the funcub thread on rc groups it flys pretty much the same on anything from 50-80mm-disclaimer added that I might be talking rubish due to lack of experience, mind you all my electrics are below wing level if this might make a difference.

cheers richie

[Erfolg]

Congratulations Richard, well done!

 

I had a look at the chat and could not find anything about the CG. I guess i rushed through to quickly.

 

If it were not for my grandchildren giving me a cold, I would have had a go in Park behind the house. At least it is not Flu this time, which they gave me before Christmas, needed antibiotics then.

 

I am contenting myself in finishing a GWS AT-6 and changing a ESC on one of my sports planes. It all takes time.

 

I will do some checks on Amps and watts etc on the planes which i have just readied so as to able to just go and fly, when a bit better.

 

The weather should be taking a turn for the worst shortly as i should have 4 planes for maidens in the next week or so.

Edited By Erfolg on 21/01/2011 15:22:23

[richard hargreaves]

Have just tried a few flights today in a little too much wind(10-15 mph but gusting and too turbulent for my levels of skill) but had to have a go due to having a new video camera to play with.

no damage to plane luckily but my sons camera skills(and my flying ability) still need a little practise.

Took up my gws 190 epp as its a bit heavier and more powerful (880g and 350ish watts on a 10x 4.7 slowfly prop) but was still a little too windy for it( ok my abilities lol) the wind sheer at tree top height didnt help much either.

Next flight is going to be in a bigger field due to the amount of downwind speed I needed to carry to keep control not giving me much time and space to react to keep the gws safe and brought home in one piece.

No damage to either plane though but I think the gws needs a paint job for better visibility against the clouds

Vids should be on youtube under the name richiehash for those who want a laugh.

All comments welcome btw.

cheers richie

[Bob Moore]

Seemed to fly well and the video was good too. I was waiting for a dramatic crash and there wasn't one!

 

10 to 15 mph sounds a bit much for me. I find it gets chucked around by turbulence from trees etc., and lack of penetration. 5mph to 10mph just about ok.

[richard hargreaves]

Yea hoping for some calmer winds this week as it looks like I've not got any work on unfortunatly-otherwise its flight sim time for a few daysto keep my fingers up to speed

cheers richie

[Erfolg]

I flew my 540 for the first time at about lunch time.

 

The wind was between 5-8 mph. With a steady 5 being the normish.

 

I personally could not cope with the CG any further back. My model is quite sensitive in pitch, moving rapidly from diving to a steep climb.

 

I also found the model to sensitive to power. If trimmed for a slowish level flight, full power causes the model to pitch up and steeply climb.

 

In roll the model initially turned to the left quite strongly, requiring a permanent right aileron trim. With respect to sensitivity to the aileron, initially very little then significant turn/roll on full deflection.

 

I had initially set the elevator poorly, setting the elevator level with the wing, this required quite a lot of up trim, to achieve level flight. The first circuit had my left hand constantly on the up trim button whilst regulating the up elevator the right hand. Though looking at the up now there does not look much at all.

 

The model could hover into the head wind, though was prone to dropping a wing

 

Although not flying straight from the board, not bad, but does still require more trimming.

 

No damage, but the fin does need more support as it flexes to much, which i will do shortly.

[Erfolg]

I have flown the model again today.

 

The wind speed was circa 2-5mph.

 

I have dialled -50% exponential into both elevator and aileron.

 

Initially I had some issues with pitch and left turn. I put quite a bit of right aileron in on trim and increased the up trim quite a bit, you can barely see it, though it took some time to get the digital trim to do anything to the flight characteristics.

 

Once the basic trim was sorted I was able to concentrate on just doing circuits, rather than madly compensating on the sticks whilst pressing the trim.

 

I found that rudder turned the model much the same as aileron. Combining both produced far more predictable and smoother turns.

 

With decent setting on pitch, opening the throttle produced a model that smoothly headed vertical.

 

What is most noticeable is how forgiving the model is from mal-manipulation. To many times I had the model in a steep turn with the nose high, and it kept flying no tendency to stall at all. I also had the model in a steep dive, heading for a re-kitting, again a bit of up had an instant response into a climbing mode.

 

I found the landings could be made to be stationary affairs, I made at least two such landings. This is important on a winter stubble field.

 

Loops are none events, though that is the limit of my attempts at aerobatics to-date. That is other than unintended momentary prop hanging.

 

Although not a competent flier of this type of model, I am very impressed. I am not sure that in anything other than light winds, it would cope well. As any slight increase in airspeed has the model climbing steeply, so the transition from down wind to upwind could be traumatic. Although up wind and downwind legs would be stress free affairs.

[Bob Moore]

Sounds as though you got there in the end!

 

The first time I flew mine I had to trim almost full down elevator till I shifted the CoG further forward. After that I had no issues at all. Rolls and inverted are fine.

[Erfolg]

I have finished the motor testing of the GC 540

 

Motor A2204 GC Link

 

using a 8*4 prop GC Link

 

Volts 8.28 max

 

Amps 6.5

 

Watts 48

 

Revs 6570

[Bob Moore]

My original figures from page 1.

With my 1600kv motor and 2s 1000 battery and an 8 x 6e prop I measured 7 amps current. The model weight is 400 gms. So if my thinking is right that is close to 60 watts a pound (ish). I guess it should fly?

 

Your test is quite close to original tests, though I suspect you have better test equipment. My model is quite a bit heavier now (with a few repairs here and there) and I'm now drawing about 9 amps with a SF 3D propeller 9x6 SF. 70 watts?

[Erfolg]

Nawww, my test equipment is basic. A standard Overlander Watt Meter and a HK mini tachometer.

 

To all intents and purposes, our results are identical.

 

Although my motor is at the limit of its viable operable range.

 

At the present weight, it seems capable of prop hanging when the Lipo is at or near max, capacity.

[Erfolg]

Having flown the GC edge a number of times now, I can totally concur with those say it is both outstanding value and very good performance, for outdoor low wind speed flying conditions.

 

Yes, an excellent £13 worth of air frame and probably £20 to 30 worth of airborne gear, incl. battery.

[wayne maddox]

hi all,need some help on this model,i cant see what all the plywood fittings are for,,,like the hex bits that come out of the undercarge supports and the 2 U shape bits.thx