Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Oct 26, 2012, 08:58 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Once I have the twin flown ... I am honestly considering a mild PKJ ! Yes a stock one .... the 222 one is stripped to bare frame now after too many crashes and repairs trying to beat her old record. The later PKJ2 is in good 'uncrashed' order but is the basis for my twin attempt, the 4400kv and stuff are benched.

So thoughts came round to whether I should hit what I term the max thr PKJ is capable of ... then relax to more sedate sub 200 speeds !!

Just to recap ........ Twin is :

2 of 3800kv 250 heli motors
2 of 4.1x4.1 and 4.5x4.5 contra props
2 of 50A ESC's with separate BEC
3S 1800 and a 4S 1500 ... first run with 3S .. then if successful - we hit it with the 4S ... short run time and possibly ESC's will be on limits ... but should be interesting.
No gyro ... but serious D/R + Expo to keep her tamed.

Calculations based on my data sheet of actual results on prev PKJ's indicates a possible speed of about 250kph with 3S and over 285kph with 4S ...

One aspect that is troubling is how to catapult ... it indicates a dead launch and only AFTER exit the rails to engage motors ... due to props striking rails if turning. This worries me because of 'panic' pushing stick fwd .. it would be too easy to push throttle too far too quick ... as it's only a matter of a second or two between exit rail and demand for power ...
I'm trying to figure out if I can design a wire cradle that lifts it enough to allow props to turn ... slide up the rails ... drop away without having prop strike ...
Initial thoughts are a cradle that is actually attached to the bungee ? That all models in fact could use ...

Ideas / sketches anyone ?

Knees are trembling already !!

Nigel
solentlife is online now Find More Posts by solentlife
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 26, 2012, 02:05 PM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
3,920 Posts
Could you use a launch dolley
http://www.rcgroups.com/forums/showthread.php?t=903514
Andy
headlessagain is online now Find More Posts by headlessagain
Reply With Quote
Old Oct 27, 2012, 12:51 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by headlessagain View Post
I used similar to this many years ago .... but now it wouldn't worjk for me as flight sites are rough ground.
I need to have something on the rails of the catapult launcher.
Second the PKJ needs to be at real speed before I can successfully control it ... something the catapult gives me.

I did consider a 4 wheel dolley without tyres ... running on the rails ... but actually a smooth frame is good enough ... just need to design it.

Nigel
solentlife is online now Find More Posts by solentlife
Last edited by solentlife; Oct 27, 2012 at 01:07 AM.
Reply With Quote
Old Nov 10, 2012, 02:22 AM
Registered User
Joined Nov 2004
1,220 Posts
Maiden was last week, completely stock but used a 4.7x4.7??? Graupner prop I had lying around.

No problem with launch and glide was reasonable (it happened to be a foamy fly off at our club).

Only issue was with the motor mount that needed gluing after each landing. I will glue in some balsa to stiffen it up.
AUSELECTRIC is offline Find More Posts by AUSELECTRIC
Reply With Quote
Old Nov 10, 2012, 03:34 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by AUSELECTRIC View Post
Maiden was last week, completely stock but used a 4.7x4.7??? Graupner prop I had lying around.

No problem with launch and glide was reasonable (it happened to be a foamy fly off at our club).

Only issue was with the motor mount that needed gluing after each landing. I will glue in some balsa to stiffen it up.
Suggest getting rid of stock mount ......... easily replaced with something like this :









Certainly cured my motor mount blues !! The above phots show my 550W set-up. My PKJ2 has same with 1.1KW power !!

Nigel
solentlife is online now Find More Posts by solentlife
Reply With Quote
Old Nov 12, 2012, 04:31 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,252 Posts
Nigel how's the PJ 2 coming along?
I am dieing in anticipation to see that beast.
AUSAELECTRIC
have a look at how I did mine.no work at all and to this day it's held up perfectly.and my PJ has had some hard meetings with mother earth
http://www.rcgroups.com/forums/attac...mentid=4007087
chop stiX is offline Find More Posts by chop stiX
Reply With Quote
Old Nov 12, 2012, 05:21 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
3,920 Posts
Stuffed my PJ into the ground yesterday. Nose now bent up and motor stick mount ripped out. Some hot water treatment, two 6x1mm carbon flats and some CA and looks good as new.
I find one of these is ideal for enlarging the slot for the carbon
http://www.ebay.co.uk/itm/Flush-Cut-...item5d35eddda1
Re-glued the motor stick and added a recessed lolly stick underneath which I then screwed through into the motor stick. I appreciate that if I have a hard landing the whole mount area will probably rip out as used to happen with the original Stryker. Build to fly not to crash.
Andy
headlessagain is online now Find More Posts by headlessagain
Reply With Quote
Old Nov 12, 2012, 05:59 AM
Wats the worst that can happen
TheCure's Avatar
Canada, BC, Surrey
Joined Jan 2009
487 Posts
I'd recommend stuffing a 1cm hollow carbon rod about 1/3 from the tip of the nose to about halfway back in the battery area.
if can be done by serrating the rod by dremelling a number of notches a few mm apart around the perimeter. Rotate the shaft like a drill would. Back it out, stick some Gorilla glue + water in the hole, and re-insert the rod. Once set, cut the front protruding rod off.
My PK is super stif and strong now. I have almost no fear of crashing now (I still would rather not).
TheCure is offline Find More Posts by TheCure
RCG Plus Member
Latest blog entry: My Mods to My RC Electronics
Reply With Quote
Old Nov 12, 2012, 07:58 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by chop stiX View Post
Nigel how's the PJ 2 coming along?
I am dieing in anticipation to see that beast.
AUSAELECTRIC
have a look at how I did mine.no work at all and to this day it's held up perfectly.and my PJ has had some hard meetings with mother earth
http://www.rcgroups.com/forums/attac...mentid=4007087
Get me out of China and I'll get her in the air !! Darn work assignment has dragged on ...

Everythings waiting for me ... the wife as well !!

Nigel
solentlife is online now Find More Posts by solentlife
Reply With Quote
Old Nov 12, 2012, 08:01 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by TheCure View Post
I'd recommend stuffing a 1cm hollow carbon rod about 1/3 from the tip of the nose to about halfway back in the battery area.
if can be done by serrating the rod by dremelling a number of notches a few mm apart around the perimeter. Rotate the shaft like a drill would. Back it out, stick some Gorilla glue + water in the hole, and re-insert the rod. Once set, cut the front protruding rod off.
My PK is super stif and strong now. I have almost no fear of crashing now (I still would rather not).
My way is to lay in two balsa spars underneath ... these not only are light and give rigidity with them and the epoxy, but also allow me to fix the velcro more securely to hold the LiPo in place.

Nigel
solentlife is online now Find More Posts by solentlife
Reply With Quote
Old Nov 12, 2012, 09:40 AM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
3,920 Posts
Thanks guys. It seems much stiffer now but I could always add another 6 x 1mm flat carbon strip from just behind the air intake to the extra spanwise carbon rod I'd already installed
Andy
headlessagain is online now Find More Posts by headlessagain
Reply With Quote
Old Nov 12, 2012, 11:47 PM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,252 Posts
Quote:
Originally Posted by solentlife View Post
Get me out of China and I'll get her in the air !! Darn work assignment has dragged on ...

Everythings waiting for me ... the wife as well !!

Nigel
Oh thought you might have been back yet.hope you capatilising while your there and buying as much rc stuff as you can
chop stiX is offline Find More Posts by chop stiX
Reply With Quote
Old Nov 13, 2012, 08:28 PM
Registered User
tobydogs's Avatar
Joined Mar 2012
78 Posts
how do i post a utube vid,it's so easy on wattflyer....i have 2 new vids of the pkj4 on wattflyers forums. under:hobbyking parkjet,need for speed.

the pkj screams the sky and i even have a few 3der foamies flying in the same video to show natural speed while the pkj is unnaturaly fast...lol.

the pkj is as follows,tp 4850kv brushless from hk,mystery 50amp esc,3cell 1300mah 30c gforce. hope to get this one dopplered again.
tobydogs is offline Find More Posts by tobydogs
Reply With Quote
Old Nov 13, 2012, 10:53 PM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,252 Posts
Tobydogs
Just copy and paste the link here.it will pull the vid through and voila
chop stiX is offline Find More Posts by chop stiX
Reply With Quote
Old Nov 14, 2012, 10:15 PM
Registered User
tobydogs's Avatar
Joined Mar 2012
78 Posts
i'v tried that more than once and this is what i get ......i copied this link from wattflyer and also off my utube channel and each time this is the result....would love to share the pkj4 vids here at rcg...theres a lot more experimenting on the pkj's here.

so heres what i get....





tobydogrc uploaded a video 39 minutes ago
4:56
SUNP0004




where the vid????
tobydogs is offline Find More Posts by tobydogs
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Hobby lobby F9F Panther EPO Jet Receiver Ready ARF smasher41 Foamy EDFs 975 Jul 25, 2014 11:11 AM
Discussion HK AT-6 Texan EPO Plug-n-Fly 29.5" w/s stuart warne Electric Warbirds 12 Jun 14, 2011 02:47 AM
For Sale HK Mini-PITTS -- EPO, Brushless, Plug 'n Fly WRXronald Aircraft - Electric - Airplanes (FS/W) 3 Aug 04, 2010 10:03 PM
New Product New HK Mini F-16 EDF Fighter Jet / EPO Plug-n-Fly CrashingDutchman Foamy EDFs 13 Jul 01, 2010 11:15 PM
Discussion HK's EPO F-16 WRXronald Foamy EDFs 5 Apr 11, 2010 02:47 PM