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Old Nov 23, 2012, 05:07 AM
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United Kingdom, Leeds
Joined Aug 2011
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Quote:
Originally Posted by solentlife View Post
Sounds about right ... Welcome to the Need for Speed campaign !

I get about 210kph on my tired PKJ with 3700 Westor + 5x5 on a 1800 3S ... when I ran a 4.75x4.75 - I dropped to about 195kph.

When I first got her going (she took so many failed launches - I nearly gave up) - she hit 222kph with the 3700kv + 5x5 + 1800 3S - that is the max she ever did. Batterys were having a hard time of it !

Thanks Solentlife, I'm glad you answered, it was mainly you I was thinking of when I asked for the opinions, but didn't want to ask. Been lurking round this thread for a couple of months and your posts have been my main inspiration for cramming more power in the back of this thing!!

I too went through the steep learning curve with the PKJ, so many torque spirals on launch, the front end has been off 4 or 5 tmes! She's now probably more carbon and epoxy than she is foam...............but nice + rigid! Best mod I did to help with launching is a foam block between the finger holes to give better grip, I can now chuck her fairly hard at an upwards angle on low throttle then "catch" her in a glide and feed in power as she falls, not had a failed launch in weeks.

Just about got thrust angle etc dialled in now and she flies pretty straight + true, may up the power in the coming weeks and chase the 222kph title!! When I put her on a watt meter last I backed off at 400w, got the throttle curve at 75% max at the minute so there's more to be had there and also 5x5 to try.

Been trying to get some onboard video but strapping a keychain cam to the top (hence the velcro in the pic) does strange things to the aerodynamics, will try again.
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Old Nov 23, 2012, 10:31 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
8,566 Posts
My 222 machine was 550W ... then she went up to 700W ... but couldn't get her to settle. The frame was badly mauled by then and I think at the extreme speeds the bumps and crimps didn't help. Put a small motor on for a while and she was fine ... ~100 - 120kph.

PKJ2 which is now the 'Evil Twin' had a 4400kv motor on and she was calculated out at 1.1Kw.
She never did get to complete a flight - tried and tried but I'd fix one thing - it would be another ... and it went on ... the machine was just too powerful I reckon.

Even with the catapult launcher - she was too much ...

As the Evil Twin - have a problem again of too much power draw on the LiPo ... so thinking on what to do ...

Nigel
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Old Nov 24, 2012, 01:01 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
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I'm a total idiot !!

There's me - gone and fitted two overpowered heli motors to the PKJ(T) ... when in fact all I needed to do was to fit two lesser motors that took bigger props !
There would be no worries about torque from a big prop as they would have been contra-rotating .... I could fit 2 7x6 props no problem.

Consider the speed of the Rarebear ... the Edge 540 racer ... both are reckoned around the 100mph range when sorted ... and that's WITHOUT 100A overloads.

I was so far down the road of high kv .... immense power with the single - I lost sigght of the twin advantage ...

Nigel
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Old Nov 24, 2012, 02:28 PM
Takeoff=Option Landing=Must
robusp's Avatar
USA, NY, Depew
Joined Jan 2009
821 Posts
Here is my interpretation of ParkJet MKII.
I got the kit over a year ago together with a complete model.
My original ParkJet is getting face lift to be a dual motor-extended fuse-canard and when I found the kit I decided to do something different.
I flew it 5 times already and it is awesome. It has 55mm 6 blade EDF with 4200kV motor. On 1300mAh 3s I'm getting 6min mostly wot flying time.
I kept it on light side, with 5g servos, receiver w/o case and short, thin wires.
It is little hard to hand lunch. When my buddy did it, he gave it good toss in to 5 mph wind and it took all I had to keep it alive.
It was lot easier using bungee. It was in fact so easy that I did it myself with radio laying on the ground while I held the plane with both hands.
It's very predictable, has excellent speed for the size and handles wind pretty good. Lots of fun, more fun actually than original configuration. I thing original one suffered from torque roll.

Rob
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Old Nov 24, 2012, 08:49 PM
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United States, GA, Jonesboro
Joined Nov 2010
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http://www.rctimer.com/index.php?gOo...productname=im still flying my parkjet with this little motor, with 3cell. its got so much power, i hardly ever go above half throttle. ive never had a plane with so much power to weight ratio. quater throttle and its still scootin along. the motor is 3cell, 2600kv, and very lightweight. ive been running a 4.7 x 4.2 prop, and i just looked at the specs & realized i can go to 6 x 4. its probably flyin 90mph now.
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Old Nov 25, 2012, 03:15 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
8,566 Posts
I thought about EDF on this baby ... couldn't decide what size to use. I note that Skyangel Screamer which is similar size has the 50mm ..... but I considered maybe a 64mm on the PKJ ?

Nigel
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Old Nov 25, 2012, 10:51 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,260 Posts
Quote:
Originally Posted by solentlife View Post
I thought about EDF on this baby ... couldn't decide what size to use. I note that Skyangel Screamer which is similar size has the 50mm ..... but I considered maybe a 64mm on the PKJ ?

Nigel
64mm??? jees!now I'd love to see that
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Old Nov 25, 2012, 10:59 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
4,221 Posts
gchrisgo34
like the paint job but I should check your workshop as somebody's broken in and swapped your gold motor for a larger silver one
I was running this 36 g 2600kv motor on my PJ but recently swapped out for a heli motor which I've yet to maiden.
http://www.giantshark.co.uk/a22088-2...-p-405607.html
Andy
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Old Nov 26, 2012, 02:02 AM
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gchrisgo34's Avatar
United States, GA, Jonesboro
Joined Nov 2010
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they were also kind enough to put the control rods on top of the wing. ive still got that motor, but i decided to maiden with the gold one since its lighter. and i just havent changed it because i like it so well. its got more power than i need. & if i went to the other, it'll just add weight. the gold motor is perfect for this plane
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Old Nov 26, 2012, 04:45 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
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Quote:
Originally Posted by chop stiX View Post
64mm??? jees!now I'd love to see that
Well - I have a reputation to keep up .... being totally insane.

Nigel
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Old Nov 26, 2012, 06:26 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,260 Posts
Quote:
Originally Posted by solentlife View Post
Well - I have a reputation to keep up .... being totally insane.

Nigel
hahahaha.true.though a 64 mm fan will eat through a 2200 pack faster than a dog that's been starved for a week on a piece of meat.there's not really space for anything bigger than a 2200.even that's big
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Old Nov 26, 2012, 06:34 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
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Quote:
Originally Posted by chop stiX View Post
hahahaha.true.though a 64 mm fan will eat through a 2200 pack faster than a dog that's been starved for a week on a piece of meat.there's not really space for anything bigger than a 2200.even that's big
My Lanyu 64mm is fed 2200 3S packs - gives me about 4 mins... in fact it's factory spec'd for 1300 3S !! (I do also run 4S 2700 packs through it - but's that me !! )

Nigel
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Old Nov 26, 2012, 06:40 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
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hahaha nice.well that's not too bad.was just thinking of space.since it's fairly limited
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Old Nov 26, 2012, 07:06 PM
Registered User
United States, KS, Potwin
Joined Mar 2012
37 Posts
Wow. I just got this http://www.hobbyking.com/hobbyking/s...dProduct=11884 motor on my parkjet. Flew it yesterday. Haven't got a chance to clock it yet, but I know its a good 20-30 mph faster than my brothers stock MK2. I am using a 4.1x4.1 on 3s. I will get some amp/watts figures posted shortly.
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Old Nov 26, 2012, 07:18 PM
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United States, KS, Potwin
Joined Mar 2012
37 Posts
Here we go. WOT is 53 amps/550 watts. A little to much considering my esc is 35-40 and I'm using 850 and 1000 nanos. It should unload quite a bit once its up and flying though. Lots of fun.
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