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Old Oct 09, 2012, 02:20 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
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Quote:
Originally Posted by solentlife View Post
My modification to twin motor set-up is on hold while I wait a couple of essential bits .... that hopefully should cure the torque problems with contra props ...

Nigel
He is another take on making a twin pusher out of a HK model

http://www.rcgroups.com/forums/showp...&postcount=947
Andy
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Old Oct 09, 2012, 12:54 PM
222 km/hr Parkjet flyer
solentlife's Avatar
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Quote:
Originally Posted by headlessagain View Post
He is another take on making a twin pusher out of a HK model

http://www.rcgroups.com/forums/showp...&postcount=947
Andy
mmmmm looks lke a couple of Radjets ... not really my cup-o-tea ...

I like a single fuselage ... the PKJ will do it well I reckon.

Nigel
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Old Oct 09, 2012, 02:17 PM
Glow 😡 no no no
Australia, SA, Evanston Park
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Some years ago someone put 2 funjets together but I'm with Nigel, no something that floats my boat.
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Old Oct 10, 2012, 02:52 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
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it looks cool,but too much of a mission to launch I would say.I still love the twin PJ idea nigel is busy with
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Old Oct 11, 2012, 01:22 PM
222 km/hr Parkjet flyer
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Originally Posted by chop stiX View Post
it looks cool,but too much of a mission to launch I would say.I still love the twin PJ idea nigel is busy with
I do apologise for the long wait ... but work gets in the way .... I get home .. start sorting and find another silly bit missing.

The motors are rigged ready to install ... it's just a couple of bits due any day now ... but I'm away on job again tmrw ! But at least sll should be here on my return and I can then get sorted and you guys can see the result.

nigel
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Old Oct 11, 2012, 05:11 PM
Wats the worst that can happen
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Canada, BC, Surrey
Joined Jan 2009
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Has anyone tried 4s with the stock PKII motor?
I have a 35A ESC coupled with the stock motor using a 5.5 x 5.5 prop.
By eyeballing it doesnt seem much faster than a 3S - however the pitch is definately higher so I might be wrong.

Would a smaller propellor be more suitable for the 4S? i have 4.1, and 4.5 sizes

Seems the ESC and motor were happy to burn through about 6 speed runs during the 4 min flight. No heat problems .
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Old Oct 11, 2012, 11:25 PM
222 km/hr Parkjet flyer
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Originally Posted by TheCure View Post
Has anyone tried 4s with the stock PKII motor?
I have a 35A ESC coupled with the stock motor using a 5.5 x 5.5 prop.
By eyeballing it doesnt seem much faster than a 3S - however the pitch is definately higher so I might be wrong.

Would a smaller propellor be more suitable for the 4S? i have 4.1, and 4.5 sizes

Seems the ESC and motor were happy to burn through about 6 speed runs during the 4 min flight. No heat problems .
You need to get a tacho and run up the different props and then calculate the theoretical distance traveled in 1 minute. You will find that probably your stock motor on 5.5x5.5 is overloaded with 4S ... but possibly passable on the 3S. I suggest you reduce down to recc'd 5x5 on the 3S and to a 4.5x4.5 on the 4S.

I run 5x5 on 3S and 4.75x4.75 on 4S ........ but my motor is a 450 heli motor of 4400kv. A 5x5 on it just pushes amps so high - the esc would be bigger than the model !!

Nigel
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Old Oct 12, 2012, 12:21 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
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Ni worries Nigel.I know that feeling.damn life and work always gets in the way of us and our toys
TheCure,as Nigel said,definitely go down to a 4.75x4.75 on 4s,maybe even 4.5x4.1
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Old Oct 23, 2012, 07:36 AM
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After a week of very interesting reading thought I would share my experience with high powered electrics and get some advice.

When setting up a large electric glider last year and moving to lipo I found that moving from 3s to 4s actually reduced power.

Power train was a 20/22/2 mega, 3.5:1 gearbox and 17x10 prop. Basiclly when using 4s the prop became inefficient and reduced power.

Now back to the pkj

Can anyone tell me in mm the throws for both elevator an alierons?
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Old Oct 23, 2012, 02:04 PM
Wats the worst that can happen
TheCure's Avatar
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Nigel, how are things coming along on the twin?

I can only sit on the edge of my seat for so long before I fall off...
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Old Oct 24, 2012, 04:07 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
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Quote:
Originally Posted by AUSELECTRIC View Post
After a week of very interesting reading thought I would share my experience with high powered electrics and get some advice.

When setting up a large electric glider last year and moving to lipo I found that moving from 3s to 4s actually reduced power.

Power train was a 20/22/2 mega, 3.5:1 gearbox and 17x10 prop. Basiclly when using 4s the prop became inefficient and reduced power.

Now back to the pkj

Can anyone tell me in mm the throws for both elevator an ailerons?
6-8 mm each way is more than enough.Mine has 6 mm on low rates and about 9mm on high.and believe that 3mm diffs,is insane,especially rollrate
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Old Oct 24, 2012, 10:24 PM
222 km/hr Parkjet flyer
solentlife's Avatar
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Originally Posted by TheCure View Post
Nigel, how are things coming along on the twin?

I can only sit on the edge of my seat for so long before I fall off...
My assigbnment in Singapore got extended .. todday I'm over the water to Malaysia .. then back to Singapore ...... expect back home sometime first week November ...

I believe all bits are now arrived home .. Wife has daily run to Post Office picking up stuff for me !!

You are not only one chomping at the bit on this ....

Nigel
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Old Oct 24, 2012, 10:32 PM
222 km/hr Parkjet flyer
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Originally Posted by chop stiX View Post
6-8 mm each way is more than enough.Mine has 6 mm on low rates and about 9mm on high.and believe that 3mm diffs,is insane,especially rollrate
At slow to moderate speeds I run at about 8mm total either (elevons shouldn't be set to add too much when combined stick) ... but as soon as I pass the moderate speed levels (100kph ~) my throws get switched down to about 3 - 4mm total. At over 200kph - even those can scare the **** out of yer !!

So I would suggest a stock set-up at 8mm full and about 5mm D/R reduced. If you start upping power as most do ... then start expecting to cut that D/R down.

I leave Full at that 8mm even though my PKJ is a 200kph + missile ... so that dead-stick I have decent control of her. But on launches and especially that I have to catapult her (she reaches over 110kph BEFORE of the rails) I use the D/R 3 - 4mm throws.

Differential ? I have maybe 1mm if that ... to be honest that was not planned .. just happened. Never bothered to take it out. My elevons are possibly 0.5 - 1mm up from neutral at centre. But that will be taken out when the twin gets in the air I reckon.

Hope that helps.

Nigel
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Old Oct 24, 2012, 10:36 PM
222 km/hr Parkjet flyer
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What happened to Speed posts ? No-one going at outrageous speeds anymore ?

Still waiting for someone to bust my 222kph ...

Nigel
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Old Oct 24, 2012, 11:55 PM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
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Quote:
Originally Posted by solentlife View Post
What happened to Speed posts ? No-one going at outrageous speeds anymore ?

Still waiting for someone to bust my 222kph ...

Nigel
I have a motor/prop combo that might get close to that,but need a new airframe,unfortunately,as life always does,gets in the way,so I have limited time for flying and playing around but I'm going to attempt
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