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Hobbyking parkjet...need for speed!!!!!!!!!!!!!

Old 06-15-2014, 03:43 PM
  #651  
solentlife
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Originally Posted by dahawk View Post
Thanks Nigel,

Yes, I hear differing opinions all over the place. Your 6X makes the most sense. One guy had told me 2X the model weight was the "rule of thumb" --Not.

I think I can modify the connectors as you suggested in order to eliminate the bump. The Jetapult™ must be less than 1/2 the ramp length you're showing. Mine is only about 26" (660mm) in overall length. Did not seem like I need a long ramp length anyway. Worked fine once I got the tension dialed in and placed a small 2" brick under the front.

One thing I have done for my heavier rail structure ... the picture I posted earlier is 1/2" pipe ... my heavier is 3/4" .... The T connector - I have cut away the upper inner side of the T and the rail is held by self-tapping screw through outside part into rail. This then stops any contact with part of my F16 .. Twister that sits down into the rails ...

I was finding that the ridge caught the aileron servo a couple of times and on one launch caused the servo to rip out ...

https://www.youtube.com/watch?v=zLnclmDh8eo

Nigel
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Old 06-15-2014, 04:44 PM
  #652  
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Good idea Nigel. This one is also 3/4 in. pipe. I think I may be able to trim back the inside ridge a bit with a Dremel but like you mentioned may need add a screw from the bottom or outside of the connector.

Frankly, it's such a short rail and because things happen so fast, I didn't really notice it catching. Looked on the underside and could not detect any scrape marks. So maybe I got lucky. Funny to watch the little Goshawk take off from the bounce like a touch 'n go.
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Old 06-15-2014, 08:36 PM
  #653  
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i am taking away the pipe insulation and am sanding down the top of the corner connector so the launch will be smooth with no bumps. also i think my angle and height could be reduced. not to much.
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Old 10-19-2014, 02:51 AM
  #654  
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For those interested.......HK has a new parkjet out. Or basically a revised one.

http://www.hobbyking.com/hobbyking/s...trSearch=parkj
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Old 10-20-2014, 08:59 PM
  #655  
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interesting...they include a 3 axis gyro with the plane, but it has no rudders. It also uses a 2 cell lipo. Not a bad price.
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Old 10-21-2014, 02:53 AM
  #656  
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i still have 2 flyable hk park jets sitting in the hanger. i seem to remember them costing something like $15 for the kit and in the day shipping was around $17,so a overpowered setup making a really fast park jet didn't cost anywhere near $80.and i don't want to know what shipping cost is today from china

my 4850 kv ,with a 60amp plush on 3cells was money well spent.
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Old 10-21-2014, 04:38 AM
  #657  
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Well I bought one of the $17 kits couple years back and after 0 luck getting it in the air I decided the small fast planes are not for me. I quickly went back to my slow flying powered sailplanes and the like. Plus my eyes are not quite as sharp as they once were so a larger model is definitely a plus.
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Old 10-19-2015, 09:00 PM
  #658  
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Default Ressurection !!

So who's up for restarting 'NEED FOR SPEED' ?

Since flying the Polaris ... which is no slow machine either ... I have been looking again at my Parkjet Twin Beast ................

I could never get this machine to launch ... hand or bungee. She just did whatever SHE wanted ...

OK ... ponder this.

My Twin has the motors mounted higher and set into the fins. She runs 4.5" props not 5" ... so ground clearance is quite good.





(Ignore props here, I know one photo has them backwards ... they were just for photos).

So lets say for arguments sake ... a couple of floats were fitted underneath raising her up of water sufficient to clear props ....

Novel idea ... gives literally largest possible take-off run I can get ...

Anyone game to try ? I shall be working on a design of floats and size to suit ...

Yeh .. I know ... crazy !

Nigel
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Old 10-20-2015, 01:02 AM
  #659  
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CRAZY MAN!!!...lol.

Sounds like fun Nigel, you need to make a drop away float so not to slow the pkj down. as for me,speeds been taking back seat to fpv'ing and looking into a larger 650 quad with gps functions and elec retracts. and a 2d gimbal for the go pro ,ect..ect. Now if the government doesn't impose some really restrictive rules with the regesration of drones I may actually go forward with the purchase. altogether $650 and change.

the famous line by Jim Cary in the movie "the mask"......."Somebody stop me!"

Sadly it may just be the government both federal and local. will know more as the holidays approach. the FAA say nearly 1,000,000 drones will be sold by christmas[this means toys also] and they are stepping up the new rules that were supposed to be in place this sept 30th but obviously aren't.

Nigel , do post a few pictures of your invention and a video of a flight.
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Old 10-20-2015, 07:43 AM
  #660  
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Got to think about height ... weight ... length ....

I think simple box floats with a step just behind finger holes.

Floats to be in line with the 'bumps' under wings ....

Rear end in line with rear of motor bell, so there is slight overhang relative to the wing.

Front end to be in line with about halfway from wing break line to the joint to fuselage.

Width ? about 1.5" ??

Ideas ?

Nigel
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Old 10-20-2015, 10:41 PM
  #661  
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If its hard to launch you may have to think about rather 'cleverer' floats that control the water drag at high speed.
In boating terms that means a deep V hull and possibly a swept back step.
The object is to smoothly loose the hydrodynamic lift and water drag without a significant change in the plane's angle of attack so it can simply 'fly off' the water. Not so easy to arrange.
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Old 10-23-2015, 09:25 AM
  #662  
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All points noted Q ....

The motors on the twin are probably going to be changed from the power hungry Heli jobs ... they really devour LiPo's.

I have ordered another Funfighter motor (same as what goes in the Rarebear) ... so added to the one I already have ... and 4S .. we should have a more reasonable power setup.
Initial trials I reckon to make with 3S in there ... see if it works first.

Very kindly ... guy in UK has sent me an unused kit of the original PKJ .. so that will be saved for final set-up once bugs are sorted.


I have to say - the interest is not only the Speed ... but the Water aspect. Since flying the Polaris ... its become like a drug ... I love flying of the water. The river at back of my house is very wide ... I have benefit of the long sweeping curve as it passes my location giving me literally all wind directions capability.
I have mind to add floats to more of my models ...

Nigel
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Old 10-23-2015, 11:47 AM
  #663  
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The Cessna 182 that is giving me real hassle on water ... will be giving up its first set of floats shortly.
They are too long for the PKJ ... but the main forward body is too short ... so my idea is to CUT them shorter on the aft section to basically provide more balanced for the PKJ.

They are light as made of solid foam ... and mounting is simply plates slotted in and epoxied into the foam.

Once I get home and playing ... should be able to post up a few photies ...

Nigel
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Old 10-29-2015, 12:18 PM
  #664  
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Ok ... here are a few starter piccies ... just fitted roughly to give an idea of what she would look like ...

I used the old spare Cessna floats and I think actually they might just work !!















Weight increase is quite minimal actually ... the model is already grossly overweight. I am planning to swap out the 'hungry' heli motors for Floater-Jet motors - same as I use on my Tu144. That way I can reduce battery reqt's to a more reasonable size / weight. I can also replace those heavy 80A ESC's with something more appropriate !! They also are Opto - so I can get rid of the sBEC ...

You can see the Eagle Tree speed sensor is still there ...

It's more a 'Can it do it ..' project than a speed one. Interesting ...

Nigel
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Old 10-29-2015, 10:18 PM
  #665  
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interesting Nigel. it may work but certainly at a cost for speed. do you think it might just nose over into the water when throttling up? hopefully that doesn't happen getting everything wet thats exposed like the esc's and motors would be a bummer.

this past weekend a fellow club member was flying a Stryker and i dopplered his passes with my phone. 80+mph except when flying into the wind it dropped to 60mph. makes me consider the pkj and funjet.
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Old 10-30-2015, 05:42 PM
  #666  
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Originally Posted by tobydogs View Post
interesting Nigel. it may work but certainly at a cost for speed. do you think it might just nose over into the water when throttling up? hopefully that doesn't happen getting everything wet thats exposed like the esc's and motors would be a bummer.
Dunno .. it really is a suck it and see ....
The floats are more than required for the model I reckon ... so she should float high and nose up.
As to getting gear wet - that's a price I can live with ... Each part will be wrapped in clingfilm to give some sort of protection, except for motors of course..


this past weekend a fellow club member was flying a Stryker and i dopplered his passes with my phone. 80+mph except when flying into the wind it dropped to 60mph. makes me consider the pkj and funjet.
But the average is the real speed so 70mph. That's slow for a Stryker ... most will hit about the 100 mark with little changes to set-up.

I'm considering taking the kit I've been sent of the original PKJ and scanning for laser cutting in balsa / depron. Fuselage of course will be unable to fully create original - so that will be own design ... A MAYBE exercise !!
If I do it .. I'll post up templates.

Nigel
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Old 11-27-2015, 09:20 PM
  #667  
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I have not forgot this one ... just too many things happening at the moment ...

I will get round to it !

Nigel
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Old 01-20-2016, 08:59 AM
  #668  
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I used to fly Skyfun Delta, very similar to plane in pics.
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Old 03-28-2016, 01:46 AM
  #669  
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blast from the past!!! i just pulled pkj#2 off the shelf and installed a rx again. i haven't flown the pkj2,or funjet,or even the recently built speedshark.

for the past few weekends all i'v been flying is quads and fpv. last weekend and this weekend i flew the superfly delta as fpv and am loving it!!! no osd to judge height or speed,all by site through the goggles.

i fly on the heli side of the club and theres no runway for bigger planes there so these hand tossed planes are the way to go and the gang there like things that go fast. i just started reprograming a channel for the pkj2 sinc it was erased to make room for other projects. hopefully i get the pkj airborne by tossing it instead of a bungee launch. i'll video all attempts for speed flight but won't be posting bad launches ...lol.....only good flights
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Old 03-28-2016, 04:04 AM
  #670  
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Cool

Some guys are converting park jets like yours including the Multiplex's
and even Stinger 64's into fpv jobs. Pretty cool to see a high performance edf weaving through the trees.

Can't wait to see your vid !

Hawk
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Old 03-29-2016, 01:44 AM
  #671  
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Just to add to Dahawks
The fun fighter series is a lot of fun as well. Wyoming outdoors out fitted the FF rarebear with this combo http://rctimer.com/product-1318.html
work great and not ough on the budget. Its a blast to ride co-pilot as wel
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Old 07-11-2016, 10:18 AM
  #672  
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Originally Posted by headlessagain View Post
Sounds like a plan to me
If it helps the cause, I have a brand new original Parkjet kit that I don't think I'll ever start (flying gliders mostly now) PM me your contact address and I'll send it to you free gratis and for nothing See, you have no excuse now! Suggest you might like to use your beat up one as proof of concept and the new one once all the bugs are ironed out.
It's the same version as in this video using just a single BW 3000 kv motor and 1000 3s pack
https://www.youtube.com/watch?v=eekUHh8jFhI
Andy
I know its an old thread .. but I have today opened the box - very kindly sent to me by "Headlessagain" over on RCG.

Its a plain white job and will get my "RAF" scheme ...

I was looking at the twin concept and to be honest I would love to just have a PKJ flying as standard let alone busting a gut on twin !

So I am looking at possibly a Fun Fighter motor on 4S or a 2826 2200kv on 3S ... so she's fast but manageable.

Its also possible I may look at strapping an EDF onto her .....

I also plan to trace out in Depron a similar shape model to create a flat wing version and see what can be pushed ...

Back to building board !!

Nigel
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Old 07-11-2016, 08:19 PM
  #673  
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OK here she is getting fixed up, first is sitting on top of Polaris as a sense of scale ..





Motor is 3000kv 250 Heli motor .. with 4.75 x 4.75 prop but that is only a thought - may change when test fly ..



Underside left plain - I think the overspray adds a bit of character !!



What's left to do ?
Add servos (MG TGY-9018MG), the control arms will exit at top of wing to put things out of way from snagging on grass etc.
Install HK 50A ESC
FrSky 4ch Rx
Test for best battery positions and mark up .... expecting to use from 1300 3S up to possibly 920 4S or more ...

I have an Eagle Tree Speed Sensor if needed. But I do not expect to hit anywhere near my previous 222kph ... in fact I had a flight of over 230kph but sadly I failed to record ..

This one is intended to be a keeper and hope not to bash her up too much.

Nigel
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Old 07-12-2016, 05:52 PM
  #674  
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OK she's RTG ....







And installation :



Canopy held by cocktail stick at front and Velcro at rear.

Balances just a shade in front of the finger holes. I can move battery back a touch if necessary. She will take either the Rhino 1250 or the normal Turnigy 1300 3S after removing one of the foam bridges of the canopy.

Nigel
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Old 07-12-2016, 10:56 PM
  #675  
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Sweeet!!! Great job painting it. Should be plenty fast with your setup. Are you adding a bungee hook and any extra carbonfiber rods toward the nose area for strength? We used to over build these lil birds Nigel. Great fun for sure.
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