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Old Jun 29, 2012, 03:10 PM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by blanik213 View Post
Hey nigel you are better off with the separate RX battery if your going to push this plane to it's limits,it will avoid any possible RX voltage brown outs or esc issues.I use a 800mah 2s to run the RX and two JR DS378 servos in my Aurora ,just my 2 cents

I fly gasoline powered as well ... with 2 "Rx" packs ... one for Radio, other for ignition ..


The PKJ has :

2 6.5gr Digital servos
1 Delta mixer
1 MEMS Gyro

60A ESC without BEC

280mA 4.8v NiMH pack

With all the parts to install they can be swapped around weight wise - allowing me quite a range of LiPo ... I can go from 1300 3S to an 1800 4S

The 280 pack should give 3 flights before recharging. The idea was that the power draw by the motor was high enough that LiPo would be in danger of giving out in flight. I also considered that a non-BEC ESC would be a few grams lighter. I know that I will have Rx power even if LiPo gives out.

But since running her - I'm starting to consider fitting a BEC I have spare .... or even fitting the 70A ESC / BEC I have sitting around.

The biggest problem though is my being in Arabian Gulf many miles away from the PKJ !!

Nigel
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Old Jun 29, 2012, 07:43 PM
BLANIK213
blanik213's Avatar
United States, NY, Phoenicia
Joined Feb 2008
665 Posts
The 800 mah 2s 20c is a lipo and only weighs 43 grams
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Old Jun 30, 2012, 05:30 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by blanik213 View Post
The 800 mah 2s 20c is a lipo and only weighs 43 grams
My 280mAh NiMH came out of a supermarket 2ch twin aeroplane ... never flew right. It's actually 1/3rd AAA cells in heatshrink.

Weighs about 15gr, charges in minutes - I put on charge while flying another model or talking, each charge lasts more than 3 flights of HARD servo / gyro use.
A 2S Lipo is bigger, heavier and too high a voltage as my gear is 6V max. except for the FrSky HV Rx of course.

The only niggle I have is no switch on it - so it's plugged direct to Rx .. But I don;t want to add a switch as it's difficult to find where to fit it, and it's added wires and weight. It's part of the reasion why I'm considering a UBEC ...

Nigel
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Old Jul 01, 2012, 03:12 AM
Wats the worst that can happen
TheCure's Avatar
Canada, BC, Surrey
Joined Jan 2009
489 Posts
i just tried a 2627 4200kv motor w/3s & 6x4 prop (stock skyfun prop).
it pulled almost 65A @ 850g/thrust. the plane weighs around 300g AUW.
almost 3:1 ratio. Only had a 50A ESC, and motor got very hot in the few seconds i had it running.
does a 4.1x4.1 prop sound more appropriate for this motor?
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Old Jul 01, 2012, 04:06 AM
Glow 😡 no no no
Australia, SA, Evanston Park
Joined Mar 2010
4,646 Posts
Quote:
Originally Posted by TheCure View Post
i just tried a 2627 4200kv motor w/3s & 6x4 prop (stock skyfun prop).
it pulled almost 65A @ 850g/thrust. the plane weighs around 300g AUW.
almost 3:1 ratio. Only had a 50A ESC, and motor got very hot in the few seconds i had it running.
does a 4.1x4.1 prop sound more appropriate for this motor?
Lol yes
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Old Jul 01, 2012, 09:53 PM
Wats the worst that can happen
TheCure's Avatar
Canada, BC, Surrey
Joined Jan 2009
489 Posts
I just wanted to do a quick test with the 6x4.
Well, with the 4.1x4.1 i got around 35amps @ 760g/thrust.
Half the power consummed for almost same thrust.
Seems a hell of alot less torque roll too.
Wish me luck with the maiden.
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Old Jul 02, 2012, 02:09 PM
Skilled crasher
Ukraine, Kyiv city, Kiev
Joined Oct 2010
81 Posts
solentlife, how do you use gyro with elevons? Cuz I wanted to use one on ailerons too.
TheCure, good luck! Be sure not to make a torque roll on start, don't use too much power!
And it;s better to use smaller battery = less weigth.
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Old Jul 03, 2012, 07:05 PM
Registered User
Joined Jun 2011
122 Posts
Pilot error...
An example of what you might find after flying with 100mph into the ground.

Luckily new kit is already ordered
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Old Jul 04, 2012, 12:08 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
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Ouch
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Old Jul 05, 2012, 03:40 PM
ICrashRCs
United States, TN, Memphis
Joined Jun 2011
1,196 Posts
Hey gang,
Is the stock stick channel at the proper depth and angle?
I hope so, it just got epoxied in.
This will be my first wing level motor mounting.
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Old Jul 05, 2012, 05:48 PM
Wats the worst that can happen
TheCure's Avatar
Canada, BC, Surrey
Joined Jan 2009
489 Posts
Quote:
Originally Posted by sashaNar View Post
solentlife, how do you use gyro with elevons? Cuz I wanted to use one on ailerons too.
TheCure, good luck! Be sure not to make a torque roll on start, don't use too much power!
And it;s better to use smaller battery = less weigth.
Havent gotten around to the maiden yet. Waiting for better servos.
i strengthened the wings using carbon ribbons from middle of fuselage to almost wing tip - along the same groove intended for the provided carbon rod.
Also did something different this time. After a few nose-ins with my other PKII, I noticed is a weak area. So, I used a 1cm diameter carbon tube, cut small slots in one end to give in shearing power, and corkscrewed it into the nose, and down a good 1/3 of the fuselage. Secured with Gorilla glue.
Its strong as hell now. the only flex is in the middle of the fuselage now - which is minor.
I think I may nose into the ground on purpose, teach it a lesson for all the times it, and gravity worked against me.
This time I have the upper hand.
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Old Jul 05, 2012, 08:50 PM
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Joined Mar 2012
78 Posts
thomas.....ouch! did you try repairing it for the experience of making it look new[ish] again. i get a kick out of how wrecked these lil birds get and yet a little 2part epoxy works magic,then sand the blisters and crushed paint smooth[ish] and repaint.....

this is pkj2 in several stages of repair with the last one being finish 2 days ago and ready to cause me grief[thats good grief]and be the screaming demon she really is...lol.

i'v been flying early mornings and the winds or heat are having me leaving the funjet and pkj home/ it also doesn't help having only one 4cell for each bird. pkj crashed and poked a hole in the batt. funjets second pack now has a swollen cell thats ready to burst.

new batteries are on order from hk.

1st two pictures were before maiden flights,2nd two pictures are after the second & 3rd crash....last two pictures show a badly beaten pkj,full of blisters,broken canopy foam and plastic now cut down to bare min amount before i come up with a new plastic canopy. so after hitting the ground hard there's nothing newish about these repairs...lol
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Old Jul 06, 2012, 08:33 PM
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United States, GA, Jonesboro
Joined Nov 2010
1,641 Posts
what kinda speeds are you getting Tobydogs? i have that motor, havent used it yet though.
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Old Jul 07, 2012, 12:26 AM
Registered User
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Joined Mar 2012
78 Posts
i know its over the 100mph mark .it's the fastest plane in the hanger and a total bear to control long enough to record passes by the video camera so someone can doppler it. every time it flys it goes screaming around and i get it trimmed only to do a death spiral into mother earth. each time it repairs it's harder to fly than the first time and requires all new trimming.

i'v been flying this week as i'm on vacation but the heats a kill joy for the desire to bungee launch,so i hope to launch it next weekend and record it's flight. i'v got a small collection of videos of the pkj's 1 and 2, but need to get music to drown out my dumb disscussions with flying bud's at the field.
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Old Jul 07, 2012, 12:41 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by sashaNar View Post
solentlife, how do you use gyro with elevons? Cuz I wanted to use one on ailerons too.
TheCure, good luck! Be sure not to make a torque roll on start, don't use too much power!
And it;s better to use smaller battery = less weigth.
Gyro has to be via Delta / V-tail mixer. It cannot use split servo via Tx.

So stop the Tx elevon mixing. Connect gyro to Aileron + aux ch for sense on Rx. Now connect V-tail mixer to gyro output and other elevator ch on Rx. Plug servos into v-tail mixer.

Now set-up gyro as low level on Rate Mode.


On the subject of weight - actually weight also helps speed as flight in fact is a factor of not only lift of wing but gravity ... ask any glider flyer. My PKJ weighs considerably more than any others I reckon and I still have the highest speed at 222 kph. With regular flights of 200+ kph when not pushing the envelope.

nigel
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