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

[Beemerider]

A question on the parkjet. Just finally getting around to assembly. Is the included roll of fiber tape to be used at the fuse/wing joint? I've used foam safe ca so far at all joints. In any pics I've seen I don't see fiber tape on wing joints. Or is the combination of glue and cf rods sufficient?

[stuart]

I don't see fiber tape on wing joints. Or is the combination of glue and cf rods sufficient?[/QUOTE]

beemer,it all depends on what you goal for the pkj is,if its just fast flying with pnp equipment you'll be fine. i used the fiberglass tape on the hing lines.

just a brief discription of mods done for the seriously over powered pkj's

used 2part 5min epoxy sparingly to join all parts.
bought a larger dia carbon fiber rod for the wings and added a thin ply floor board to strengthen the fuse front to back. this also allowed for easyvelcro battery straps to be located for battery. also added a carbon fiber rod just behind the leading edge of the wing so theres no wing flex in snap rolls or turns.

used extreemly thin birch to strengthen the ailerons and added the unused carbon fiber rods on the te of the ailerons.

tossed the stock motor mount for a better built in the stick mount and beefed it up with a circle of ply and epoxied in place then bolted the motor in.[pictures show different mount used.]

for the pkj4 i'm flying now,i used fiberglass packing tape over the hings and change out the stock thin servo push rods for my own rods. also put servo arms through the top of the wing.

hatch is held in place by small plastic thumb srcewsat the back of the canopy and a dowel for the front.

power for pkj4:TP 4850kv motor, 50 amp mystery esc,1300mah 30c gforce battery.5.5x4prop[i think...it been changed a few times].

i would consider using the tape you have to make a few hing stregthening points and perhapes down the wing joint areas.i don't know what the strength of foam safe ca is or if it's brittle when flexed. i can't wait to hear of yours and mikes first impressions of the pkj in flight,they'er great!!,the pkj blows my funjet away for causing high heart rate.

a few pictures of different mods done to the pkjs, first picture motor was a 2200kv,second motor is the dons wicked 3000 on 4cell,third motor is the tp4850 kv. i firmly believe the dons wicked will produce the greatest speed....it's just a handful to fly and i may move the motor forward and use a smaller 4cell then previously used.its pretty beat up right now so a new airframe may be on order.

[stuart]

very important!!! do not use the alum motor mount pictured on the second motor picture as they cant support the power of the dons 3000 on 4cells and will break. the mount in the background is what i'm using now for pkj2.this is how it is now...

[stuart]

NIGEL!!!!!!!!!i'm bummed man. i just surfed the hk planes and they don't have the pkj kits anymore...only the ones with the motor for $49 .out of stock in china but in stock in the usa warehouse. i refuse to spend the extra bucks for the airframe. i hope this changes since the success of the pkj4 and a renewed desire to rebuild pkj3 with the 3000kv 4cell.

[solentlife]

Originally Posted by rcers

Well I am going to join the ParkJet club but Nigel I fear you won't approve. I am going the "other" direction. I have a hot little 25g motor and will use a light 3s 1000 mAh pack. That motor on other planes with a 5.25 X 6.25 APCe prop has proven to be one excellent performer.

With ultra light servos and RX I should be able to get 8-9oz or so. I am guessing that my setup will go pretty well.

With that nice over square prop I usually get about 80mph on my sleek planes but can see what this yields.

Should be close to a whopping 110w or so. LOL!

Mike

I ran a small motor after blowing the hottie I used ... and really enjoyed it. It doesn't take much power to get this baby motoring ...

Nigel

[solentlife]

Originally Posted by stuart

NIGEL!!!!!!!!!i'm bummed man. i just surfed the hk planes and they don't have the pkj kits anymore...only the ones with the motor for $49 .out of stock in china but in stock in the usa warehouse. i refuse to spend the extra bucks for the airframe. i hope this changes since the success of the pkj4 and a renewed desire to rebuild pkj3 with the 3000kv 4cell.

That's not funny ..... I've just surfed and searched HK ... only the PNF's listed ....
Pity we can't identify original source of the PKJ ....

Nigel

[solentlife]

The simplest way to strengthen the elevons is to add a sheet of thin balsa to the underside of them. If you use epoxy spread thinly and then add 1/16th balsa sheet ... - the stiffness of balsa and epoxy makes those elevons rigid. The balsa can then be sanded at edges to blend in.

Nigel

[dahawk]

Here's some double-trouble for ya !


http://www.rcgroups.com/forums/showp...postcount=1037

[solentlife]

Originally Posted by dahawk

Here's some double-trouble for ya !


http://www.rcgroups.com/forums/showp...postcount=1037

Seems people have a passion for doubling up the Radjet .....

Weather here is e ... -3C ... snowing ... vis is ok for Cessna and slow stuff ... but anything lively - forget it !

Thinking to put the floats or ski's on the Cessna ...

Nigel

[rcers]

Got mine yesterday. I know regular CA is safe but I am not wild about how brittle CA can be. Anyone using anything else?

[dahawk]

My favorite is Beacons Foam Tac but having a hard time finding it. Thus been using 5 min epoxy on the epo/epo foamies.

[dahawk]

Rattlesnake broke the 150mph/241kph barrier today with his 6S Raddy. Whoa !

[stuart]

rcers,use 2part 5 min epoxy spareingly. i use rubbing alcohole and paper towels to clean off the squeezed excess and the wings and verticals have never given up even on those less than perfect landing otherwise know as "ground pounders","lawn dart"...ect...ect....

[rcers]

OK good to know.... thanks guys...

[rcers]

One more question - what throws and expo you guys using?

ML

[stuart]

i haven't made measurements but can say the throws are set to very little to medium. the parkjet at high speed reacts lightening fast even on low rates and its why guys loose control. once launched and trimed at low rate,it will roll like a spinnig top. what i like about the pkj is once trimed it flys on rails. expo is a must...i have a lot dial in to do aerobatics and not wanting to over control.

i can't wait till my new tx arrives so i can reprogram 8 planes into its memory. biggest hassel with the pkj is the initial trimming.she is a handful if the controls are off. once in the air i recomend high altitude and half throttle speed for trimming,wot may cause it to climb but i always fly high to coast and keep things cool. on a 1300mah 30c gforce i get 5 min flight times due to the method of gliding into position for the speed runs. this also removes the dive factor when i finaly get the speedo doppler to the field and makes the low and close flybys safer.

do paint it in bright colors as its easy to loose sight of...lol. and post some pictures,it's great to have someone else doing the pkjs

[solentlife]

For general stock speed ... 5mm +/- will have it dancing .... any more than that and you'll be picking up the pieces !

Once you get up to the 200kph ... the movements are TINY !! as Stu says - it spins like a top on roll rate ... and for elevator - it can flick up and over so fast it's a roller-coaster ride.

I have 70% expo on ... YES 70% .....

Nigel

[rcers]

Thanks guys!

[rcers]

OK it took to the air today. Exactly 250g AUW ready to fly (a light weight for sure). With the hot wind custom CDR motor it is running about 125watts total with a 5.25x6.25 APC speed prop. It scoots right along! I am very happy with the "low" power option.

I would estimate about 80mph or so. And with ~222w/lb it has pretty decent performance. New packs I was being nice but suspect I will get even a touch more then they are broken in a bit.



Mike

[solentlife]

Originally Posted by rcers

OK it took to the air today. Exactly 250g AUW ready to fly (a light weight for sure). With the hot wind custom CDR motor it is running about 125watts total with a 5.25x6.25 APC speed prop. It scoots right along! I am very happy with the "low" power option.

I would estimate about 80mph or so. And with ~222w/lb it has pretty decent performance. New packs I was being nice but suspect I will get even a touch more then they are broken in a bit.



Mike

Congratulations ............... you must be a one-off !! You actually flew a maiden PKJ without smacking it !!

Lovely - glad you had a ball with it, and I hope our info went some way towards that ...

Now to see how long it is before you get the 'itch !' to go faster !!

The stock PKj will hit about 120 ish KPH ... with most pushing stock with better battery's to about 130kph. Then things start to get serious above that !

Well Done !

Nigel

[rcers]

Yep I did a "launch" flight condition on the DX18 and managed one flight one quite well, flight two launch was pretty close to terra firma when I got on it.

I think I may try the side arm toss on the next launch.

The setup advice helped I have about 5mm of throw on low rates and about 60% expo so it was actually very manageable. So thanks indeed!

Mike

[gramps2161]

I got this in the email the other day for a new foam safe CA from 2dogrc. It is suppose to remain flexible and not get brittle like regular CA. I am going to order some and see how it works on a foam build I am going to do.
Figure I might as well post it since the question of glues came up in this thread.
http://www.2dogrc.com/bob-smith-foam...safe-glue.html

[solentlife]

Thats great Mike ...

Never been brave enough to do a side arm throw ! To be honest - I'm worlds worst chucker ! My flying pals don't ask me now - having seen my abyssmal efforts !

We have one guy who can launch just about anything ... so he's the guy I zero in on for maidens if possible.

Nigel

[stuart]

gramps ,that link didn't work for reading info on the new glue you found.

mike!!!outstanding man!!! so glad your pkj was succsessful and now you have to get us a vid ...i can't stand having to sit out on the side lines waiting for my new tx to arriveshould be in stock around now]. i have the gopro silver camera to wear on a headband mount. looking forward to getting doppler readings on all the pkj's. so try to get a close to the camera flyby for a sound check. nigel,i really expect the pkjtwin to perform top notch....she'll be another bird to doppler. i have better control now of the funjet& pkjs for closer flybys so may also give the radar gun another attempt but won't be holding my breth on that.

heres a rcspeedo question,if a video of a plane being dopplered by say an android phone says 104mph but my doppler reading off the laptop is different..... would the temp of the gps readings on my phone here being different than the phone in the video change the doppler reading very much?

i now have the android charge by samsung,i let my son have my upgrade and took his phone .he downloaded rcspeedo onto it and it works off test videos with slightly different reading. i guess being at the field will be the best test of all.

[gramps2161]

Stuart the link is fixed thanks for pointing it out.