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

[solentlife]

So 10m of 6mm Bungee on way from HK ...... I have plenty of fishing line as I fish a lot.

Joint of bungee to line via plastic light ring of course to stop fishing line cutting bungee. The bungee tied and bound back. End of line to PKJ will have a small red flag and again light plastic ring for hooking onto PKJ.

I reckon hook should be just behind that air-hole in the underside of PKJ.

[solentlife]

Here's ideas coming up !

catapult system with bungee :

http://www.scalesoaring.co.uk/VINTAG.../catapult.html

Standard launch techniques for gliders with bungee etc. :

http://www.scalesoaring.co.uk/VINTAG...ngGliders.html

scroll down of course for the Bungee system.

Now that catapult system allied with my rails ??

[stuart]

NightFlyyer-a-Pult R/C Plane Catapult by Dave. Self Contained ...
10 min - May 25, 2009
Uploaded by NightFlyyer
www.youtube.com/watch?v=IKM1CQvpbqs

NIGEL andNJS!!!!!!!check this out!it's a smooth launcher and equals a good toss by a strong thrower. it's self contained. i watched many edf/funjet bungee launches and crash videos to see it's still a rough launchgoing off the pvc rails. this is a simular concept i had where a pin would stick up about 3/4 to 1 inch up a wood rail that would have a bungee cord inside the rail.and pulled down around the back for maximum tension,you would pull the pin down and lock it in place.no need for a hook as a simple hole in the fuse might work,and at the last few inchs of the run of the rail ,a routered angle in the rails slot would drop the pin flush thus freeing the plane.

i'v only veiwed this vid of nightflyers once but thought i better move the vid here before i lose it like i have so many videos viewed in the past.


if i start to build a launcher,the "bot" is going to fall way behind,and i would ike to get that bird in the air before wood starts to warp sitting on the workbench.

by the way,even though i didn't fly the funjet andpkj1 in front of a crowd on sunday,i did fly the skimmer twice for 15min+ flights searching for lift,and the aj slick twice until i could see the rudder fluttering do to loose cables on the pull/pull wires. had a great day warming up the thumbs to sticks on saturday....so should be feeling comfortable to speed run hopfully soon. i am in no rush to break the record you'v set nigel..lol.. and i tracked my package from hk as leaving hong kong on the 14th. my order of the 4850kv and v3 should be here soon.

what do you think of the way bungee launchs looks on line and what do you guys think of this design?

[stuart]

smaller in designe and a little less power.....seems doubling up the bungee inside the tube might increase power. what i love about these vids are the many choices to view afterwards.



J-Power L-39 bungee launch - YouTube
3 min - Apr 11, 2011
Uploaded by Skippy347
www.youtube.com/watch?v=a-7MnC62WNY

[solentlife]

two points about Night flyers catapult :

a) He's using the F35 which is a fast well powered EDF that hand launches a dream. What we need to see on there is a pig of a model as I think the run is too short under bungee.
b) We need clearance for the prop ... that flat bed will be a problem. So that's why I advocate rails. Note he's used same rails but put a ply top to it.

[solentlife]

this is what I'm thinking of ... but more steady on the rails !

YouTube Video

http://www.youtube.com/watch?v=l9ctQ...eature=related

and this one ...

YouTube Video

http://www.youtube.com/watch?v=kNVrn...eature=related

There's loads of the rails and bungee sort.

OK ... one item you will see when comparing Nightflyers self-contained vs the normal laid out bungee type. The speed of launch and pull of the laid out traditional bungee is higher. Why ? The bungee is allowed it's full length to pull in required direction. The pulley version has the bungee disconnected at a short distance but still pulling - but now nothing is connected. You will get an initial gain from having the extra bungee doubled length but in fact the run is too short to be fully effective in our PKJ case I believe.

[solentlife]

This last one is more relevant I think as he clearly shows he's not giving power till after it leaves the rails ..

YouTube Video

http://www.youtube.com/watch?v=2GZYE...eature=related

I think that will still be a factor in success or not. The feeding in of power and when.
One of his launches falls flat on it's belly ... too late on power. So when / how much power ?

s it necessary to have the second line coming up to model or can it be the bungee and then line to trigger ?

Why do most set the model halfway up the rails and not use the whole rail as guide ? I think for our PKJ that needs steady till it has speed - the further back and distance to run on rails is called for.

I am also hoping that my launcher which will be based on :

YouTube Video

http://www.youtube.com/watch?v=UviIG...eature=related

YouTube Video

http://www.youtube.com/watch?v=t9HKn...eature=related

will also launch all my intended models incl. EDF

Funny - watch Part 2 at the end ! It happens to all !

[solentlife]

YouTube Video

http://www.youtube.com/watch?v=9tP9-...eature=related

Oh man ... I shouldn't laugh !!

He does get it to work in second vid. But he launches so close to water !! Man - I'd die waiting for the PKJ to death roll into the water !

It's decided then - I have the plumbers tubing ... I have suitable ply to create the trigger / bed etc. I have the bungee coming ... I have fishing line and red cloth ... I have key rings.

I just need to get home and put it together.

Wonder what my Cessna would do on it ?

[stuart]

Nigel my friend,my v3 arrived today with the towerpro 4850kv motor. the motors the perfect size for the park jet .....but heres a question on the v3. the tubes smaller holes located behind the front of the tube is supposed to be extended at least 1.2 inch past the leading edge of the wing and as seen by my first location it isn't. in fact ,mounting it in the canopy as far forward it only went as far as your mount...shouldn't we be pushing the tubes secondary hole past the curves of the nose,or at 100+mph runs we may get miss readings. it looks like the last configuration is what is right and of coarse very risky to the tube on landing. nothing is glued in and i did add epoxy to the tube joint ,like you said,its not epoxied very well.

as far as the launcher goes,the best looking to me was the one using only a short piece of bungee launching the funjet,other wise the pvc frame looks to be the safest and more easily used for larger gliders if needed.

[solentlife]

I reckon your position of tube is fine ... in fact I will change mine to that. I have to feed my tibe through the nose of the model ... but yes I have my static holes more fwd than yours.
If you think that your position is not good - think about those who fit to wing LE ... all the vortices / air flows that are coming of the nose etc. ? Reckon your position is better and fine.

Glad you got the bits - now go break my record !

[solentlife]

Guy on RC Groups .... he fitted the Stinger wheels to his Parkjet ! Now I have a set on my 50mm T45 EDF that I am thinking about removing ... plus I have a set of mini retracts. I have a bag of small wheels about the smallest that you could use ... 20mm diam.

How much speed loss if a set of retracts are fitted ? I know the fixed wheels would drag terribly ......... but retracts ?

Front leg would have to fold forward I think to clear ... mains no problem.

Hey ... I'm having silly thoughts !!

[stuart]

will be building a launcher,first gotta take the pooch to the vet,then off to Lowe's to p/u PVC pipe,fittings,wood ,ect...ect.....

when i here it takes longer to shop for the material than it takes to build ,i would agree since Lowe's is our idea of a toy store for building stuff,i have a list in hand and may make mods as i go thru the store.

i may make the launcher that allows me to adjust how wide the bars are so i can handle larger wings should i have to. i may have a problem with using stakes in the ground as we're not allowed to poke hole in the ground do to the field being an old buried refuse dump covered in a membrane and soil ,and then grass.if this is the case i will have to weight the bungee cord out in the field ,and possibly switch the design to a smaller pedal release design. Lowe's also sell the latex tubing to be used for garden and water purposes ,but its exspensive...1.80 L/F x 20 ft.

i may still research latex tubing later as i hate to spend $40 for the bungee.

will post pictures of the finished product and will be hopefully testing it with pkj#1 if the weekend doesn't rain out.

[solentlife]

Hobby King ........... $3.99 for 10m bungee ....

mmmmmm not allowed to poke a stake into the ground .... you do realise the pull that's on a bungee ? I think they usually reckon you need 5 - 6x the model weight tension. Bungee also stretches about 6x its length.

You will need some heavy sandbags I would suggest with brick or something other side trapped by the sandbags.

How deep is the soil ? It must be reasonable depth - grass won't grow on shallow ground ... well it does but soon dies of ...

Stu - what you think about my Retracts idea ??

[stuart]

i may build this due to the simple pedal launch and i can lock the rail to the fence post when i leave the Field. as far as weights go,i have 50lb weights from a barbell set i used to use.....1 should be plenty and the little spikes holding the pedal launcher shouldn't cause a stir.


http://www.youtube.com/watch?v=iNh62...ture=endscreen





my son had to help me move the video,i will be doubling up my 18ft of bungee and add nylon heavy gage fishing line or builders jet line tied to the key rings for connecting to the pedal and plane. the alt build is larger with sliding rails and needs to be piked down front and back of the launcher. what to do?


now then........wheels? retracts??? we need to ditch all weight and scream the sky for speed!! not ease of launching, but alas...we digress...lol.

[waydrantsaita]

spam

[solentlife]

NA - I spent quite a bit time around Curacao / Aruba with Shell. Willemstadt, Bullen Bay etc. Wonderful - would love to go back. Dk they still have the floating pontoon bridge with outboard motor in Willemstadt cut?

Welcome to our crazy Parkjet world !

[solentlife]

Originally Posted by stuart

...................
now then........wheels? retracts??? we need to ditch all weight and scream the sky for speed!! not ease of launching, but alas...we digress...lol.

Years ago when I did slope soaring - we used to ballast our slopers to get more speed and penetration ............ my PKJ is near 500gr which I believe is nearly double design weight ?
The speed of my PJ does not suffer by the weight - in fact because gravity and fwd momentum are factors in flight - may actually assist in my amazing speeds.

I'm talking fitting retracts ... not dangling wheels causing drag. So I hope to have a clean airframe with wheels up. Think of the take-off runs !!

OK .. I have LiPo's that I cannot use in the PKJ because the 450 motor on back end is so heavy. i need big lipos to balance. If I fit retracts - that may help me use my smaller lipos. That will offset partly the increased weight. The retracts I have are mini electric jobs and need no servos.
I am thinking to order another PKJ and that will be my model to apply all the lessons learnt. My existing beast to be the test bed for all the crazy ideas !

I need to get to that elusive 300kph !

Anyway Stu - what are you doing ... why are you not up with me in the 200kph arena ? C'mon guy - get moving !!

[solentlife]

PKJ Elevons ....................

More I think about them - the more I agree with others who have removed the foam ones and replaced with balsa.

I'm even wondering whether they can be split into aileron / elevator halves ?

[NJSwede]

I'll finish this baby tonight (it's been delayed a bit because of the gorgeous Slick i received), but you guys scare the cr*p out of me with your stories on how difficult it is to launch. Then again, I'll fly it with a small motor and a 1300mAh, so it might be a bit floatier than Nigel's brick...

[solentlife]

Originally Posted by NJSwede

I'll finish this baby tonight (it's been delayed a bit because of the gorgeous Slick i received), but you guys scare the cr*p out of me with your stories on how difficult it is to launch. Then again, I'll fly it with a small motor and a 1300mAh, so it might be a bit floatier than Nigel's brick...

Ha Ha !!

Can we have a vid of launch and flight pls ?

When you do the low passes ... can you try and keep them straight and level past you and try to keep others from talking over the motor sound ? That way we can doppler the flight. Talking disrupts the sound file ...

But what would be nice is a commentary from you as you fly - with quiet at the low passes - so many vids are just model and little else ...
Would be nice to hear impressions etc. while trimming etc. The pilots info while flying ...........

[stuart]

hey there pontus,i hope you get better weather then i have,to windy to fly here in northern nj.or at least to windy to go for the ride and see.

after i do a yard cleanup,i'll put together the launcher and p/u a cheap hang type fish scale to regulate how much tension to pull the bungee.

hope you get home soon nigel ,and post a few vids for us to watch.....looks like rain for today,and tonight....sunday afternoon.

[solentlife]

Bloody client still won't let me go home even though I'm stuck doing nothing !

I am more determined now to make the Retract idea work on the PKJ .. I'm one of those who cannot lay down and let it go ...

I know from previous models I had with retracts .. Spits etc. - that cleaning up the wheel / leg section meant more than the weight penalty. Lets be honest reason full size retract is to get rid of drag.

With my power plant - I reckon even with wheels down I'll be creaming past !!

[solentlife]

Bloody client still won't let me go home even though I'm stuck doing nothing !

I am more determined now to make the Retract idea work on the PKJ .. I'm one of those who cannot lay down and let it go ...

I know from previous models I had with retracts .. Spits etc. - that cleaning up the wheel / leg section meant more than the weight penalty. Lets be honest reason full size retract is to get rid of drag.

With my power plant - I reckon even with wheels down I'll be creaming past !!

[stuart]

well, i gotta go to home depot to p/u yard supplies....what a waste of money that could have been spent on the hobby. i don't want the neighbor ganging up on me.

i only posted to calm nigel down...lol....your double posting now that you'v been away from flying for to long. common man,go highjack a real plane large enough to get ya home,and small enough to hide in your back yard...lol[i think it's a good idea]

[solentlife]

OOOPs !! How'd that happen ?

That Jet on the runway - same one as in the film, WIND ... the fictional America's Cup movie ... may be fictional - but a very good movie showing sailing boats on the edge.