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Old Dec 08, 2012, 03:04 AM
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Kingston, Canada
Joined Jun 2004
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Hopefully the motor should be close to the aerodynamic thrustline. It's done after the rest of the CG/elev. trimming is done just to fine tune it. Only works for symetrical or semisymetrical airfoils. Nothing to do with fullsize aircraft as they don't have the power to weight ratio that the models have. Also not set up for sustained inverted flying, like the models are. What I meant by " may not work for everybody" was, You may not like this method and may prefer your own. Not into semantics. I like things simple Try it, you may like it. Why criticize it if you haven't tried it. Been setting them up this way since about 65.

Gord.
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Old Dec 08, 2012, 10:39 AM
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Joined Aug 2005
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Quote:
Originally Posted by scruffy1 View Post
on your suggestion above, the cg is at 44% if the front of the (swept) top wing and the rear of the (unswept) bottom wing are considered the edges of the chord
With a swept top wing you'd measure from the mid-point (half of the sweep) of the LE edge of the top wing to the TE of the unswept lower wing. That will give a truer approximation. No criticism intended, just curiousity. 44% would be way back but in-accurate if measured near the fuselage rather than half-way down the span.
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Old Dec 10, 2012, 06:44 AM
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Australia, QLD, Mountain Creek
Joined May 2012
151 Posts
gee Scruffy, It's getting all a bit too complicated over here

I like the Pitts, are we are starting to get along much better, but when a long weekend at Rainbow Beach presented itself, there was no way we had the room to take it.This
Wing at the beach (6 min 38 sec)

is why I am converting to the dark side with wings
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Old Dec 10, 2012, 07:31 AM
looking up down under
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Australia, NSW, Fairlight
Joined Feb 2008
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nice !

and the plane too...
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Old Dec 13, 2012, 01:24 AM
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Australia, NSW, Fairlight
Joined Feb 2008
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went out after my repair session, and this time remembered to take the anemometer with me

10kph gusting to 15 - no problemo !

i had "upgraded" the prop from what i presume is the sf e-prop 8*3.8 that was supplied in the kit, to the TGY Slow Fly Prop 8*3.8SF w/ shaft adapters as the original item had bent enough to be a risky prospect for shedding a blade

wow ! much different despite the exact same specs - this thing allows me to go vertical almost endlessly at full pace - not surprisingly it also meant i emptied the battery sooner, and i predict it means i am going to need to back off to a 6 minute timer to leave 20% in the tank, or fly more gently

which means i will need to back off to 6 minutes because it is unlikely i will back off gunning the motor
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Old Dec 15, 2012, 06:42 AM
looking up down under
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Australia, NSW, Fairlight
Joined Feb 2008
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so good that i crashed again

took to going slow and was having a great gentle stunt fly, then got a little wild too low down and bit the dust

broke a strut, and bent it half way up as well

ha! i had cleverly traced the struts and the baldachin into the booklet that came with the kit so i could whip up a new one should the need arise - great idea, except i threw the book out tidying up last weekend

memo : stop flying crazy at under 50' or cop the consequences
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Old Dec 26, 2012, 02:56 PM
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Joined May 2012
151 Posts
Hi Scruffy,
No pics or video , you'll have to take my word for it but the Pitts and i kissed and made up. Finally got the best mix of battery, battery position, prop and trim on all six control surfaces and bugga me, it has become a throw it in the air and bang the stick about and then a controlled landing type of plane. Obviously just experience on your side to get to this point much faster than me.
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Old Dec 26, 2012, 09:22 PM
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Australia, NSW, Fairlight
Joined Feb 2008
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way to go, my friend

i've replaced the strut and then busted the baldachin again this afternoon (same split, now much better repaired)

it flies beautifully even in reasonable wind - sadly i don't pilot as well as it flies (yet)

but yeah, once it's trimmed it is a sweet bird

have fun ! and seasons' greetings
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Old Dec 27, 2012, 05:27 AM
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Australia, QLD, Mountain Creek
Joined May 2012
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Best wishes and a happy crashless New Year to you as well. Thank you again for your invaluable help that i needed during the build

This is my choice every morning, mostly i take both
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Old Jan 25, 2013, 05:14 PM
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Australia, NSW, Fairlight
Joined Feb 2008
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modifications to the set up

having gotten more deeply into the capabilities of the dx8, i have unlocked the mystery of mixing enough to realise that life is easier with a zero / zero thrust line if you utilise the throttle to elevator mix ability

as a consequence, full throttle gives me speed but minimal zoom (adds down elevator), and minimum throttle leaves the nose high and floaty (adds up elevator)

obviously this doesn't work the same inverted (although it would be possible to add a switch for that instance), but working the elevator inverted is a skill i need to improve anyway, and i mostly fly upright if i am level

on the dx8
>function list >mixing >mix > >mix1
set the control as THR > ELE
mine has rates of 15% 10%
offset of 50%
Trim : Act
Sw: Mix0

offset is where the zero point is on the mix (neutral, being 50%, or mid throttle position)
rates are for up and down, but i can't recall which one is up

work on that for yourself

the other epiphany was the use of an onboard lipo voltage meter with audible alarm, which lets me use all the safely available battery capacity whilst keeping the discharged resting voltage just under 3.7v

i cannot recommend this thing enough, but you can read all about it on this link on my blog, as i have already raved enthusiastically about it in that post
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Old Aug 21, 2013, 03:05 PM
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United Kingdom, England, Tamworth
Joined Apr 2013
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Can anyone tell me what CofG measurement they used at the lower wing? My dad finished building it today. Using 1300mah batt and it was dropping the nose alot. Any advice cheers?
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Old Aug 21, 2013, 11:20 PM
looking up down under
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Australia, NSW, Fairlight
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Quote:
Originally Posted by Shep0479 View Post
Can anyone tell me what CofG measurement they used at the lower wing? My dad finished building it today. Using 1300mah batt and it was dropping the nose alot. Any advice cheers?
balanced inverted with a 1300mah lipo in, mine's balance point is essentially where the rear of the leading yellow stripe hits the tip, which is somewhere between 1&1/8" and 1&1/4" from the lower wing leading edge

worth noting that was with my 97gm lipo; my heaviest 1300mah is 113gm, and i don't change anything trim wise for difference in mass

hope that helps

enjoy the pitts - mine is still my favourite powered aircraft (but i will build a reaktor in the next few months, so i might alter that view)
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Old Aug 23, 2013, 03:48 AM
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United Kingdom, England, Tamworth
Joined Apr 2013
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Quote:
Originally Posted by scruffy1 View Post
balanced inverted with a 1300mah lipo in, mine's balance point is essentially where the rear of the leading yellow stripe hits the tip, which is somewhere between 1&1/8" and 1&1/4" from the lower wing leading edge

worth noting that was with my 97gm lipo; my heaviest 1300mah is 113gm, and i don't change anything trim wise for difference in mass

hope that helps

enjoy the pitts - mine is still my favourite powered aircraft (but i will build a reaktor in the next few months, so i might alter that view)
Thank you very much. Hopefully this will sort out the problem. Cheers
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Old Aug 23, 2013, 04:00 AM
looking up down under
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Australia, NSW, Fairlight
Joined Feb 2008
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Quote:
Originally Posted by Shep0479 View Post
Thank you very much. Hopefully this will sort out the problem. Cheers
if you look through my thread there are lots of tips on trim, as i was completely ignorant of the cg despite some hints, and as the baldechin isn't entirely "fixed" in where it ends up situated, i suspect there's variations to be had

with the cg as noted for me, it is a really sweet machine, and still going strong despite several repairs and more propellers (the 8038 is fantastic)

have fun !

pitts redux (3 min 3 sec)
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Old Aug 23, 2013, 06:01 AM
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nice flight music thanks I will have a more in depth read. cheers
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