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Old Feb 26, 2012, 02:03 PM
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speed to beat unless someone shows otherwise




138mph
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Old Feb 26, 2012, 08:30 PM
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shauntot's Avatar
Joined Aug 2005
412 Posts
YOU GUYS ARE INSANE! (in a good way) - way to go for trying to max out the pj..would love to see a video of those insane speed runs!

btw - i created the rail launch gun last weekend...copied the one I saw on the youtube video

Hobby King EPO ParkJet Launch Gun (0 min 14 sec)


unfortunately either my pj's motor (stock mk2) is too weak and this guy had a different power system altogether because my pj couldn't take off properly from the launcher and would just flop down on the ground as soon as it exited the rails. oh well, time well spent on a weekend, anyway i have a new project for the pj this week which is to mount a keychain cam on it which i got this weekend as well.

rock on pj speed junkies!
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Old Feb 26, 2012, 08:57 PM
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Joined Mar 2010
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bummer to hear that on the launcher...i had hopes it would work also.

i plan on trying something using a fiber glas rod. i hear it won't work but then i.v nat seen anyone try it yet.

the plan is to mount a fiberglass rod used to mark driveways in the winter into a 2x3 wood stud. these rods can be pulled over all the way without snapping[like a fishing pole] and they are extreemly powerful! if i adjust the angl and provide a stop method so not to wip past vertical...it might toss the parkjet far. i won't have to pull it down more than a few ft to be way stronger than a human toss. if it works,i can plug the pole in at the field and have a buddy pull the parkjet back while standing on the 2x3,holding onto the wing with 2 fingers and my powering up to 1/2 throttle would be awsome if it works. trial and error are the experiments fortunes are made from. the glass rod only cost $4.


as far as the power in pj#2 goes,these are dons rc readings for the wicked 3000 thats installed with the 80 amp esc.


Here are test results for the Wicked 3000 ( all data with APC props):
3S lipo:
Prop RPM Amps Watts Pitch Speed
4.7 x 4.2 26000 rpm 30 amps 320 watts 104 mph
4.5 x 4.1 27900 rpm 27 amps 290 watts 108 mph
4.1 x 4.1 29400 rpm 23 amps 260 watts 114 mph

4S2250 Long Max lipo :
Prop RPM Amps Watts Pitch Speed
4.1 x 4.1 36200 rpm 35 amps 510 watts 140 mph
Larger props are not recommended on 4S, and when using 4S the motor must get good cooling.
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Old Feb 27, 2012, 12:16 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,260 Posts
Guys I reckon mine gets around 152km/h still need to do a proper speed test though.but I'm busy slapping some color on it
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Old Feb 27, 2012, 08:00 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
9,133 Posts
Quote:
Originally Posted by Jpette View Post
I was amazed yesterday to see how my new paint job helped to follow the plane .
For the first time I could relax a bit and be sure of what was happening !!

This plane is a real blast !! I never go back to the real Stryker that feels like a pig compared to this crazy one .

My 4S-1000-30C batteries are limiting me by know and if I want to get more pitch , I"ll need to get some better ones first .

Anyway, I love it so much like that that I"ll wait for thoses batteries to dy first and then Solentlife better you watch for your six cause I'm coming and fast on you !!
Go for it .... if someone beats me - makes me all the more determined to push harder ! I'm planning on 300 kph in the next few weeks based on gear I've ordered for her.

Don't forget we need data .... motor, ESC, LiPo, weight, prop, speeds, how speeds obtained ie doppler, sensor etc. so others can benefit from our work.
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Old Feb 27, 2012, 08:10 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
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Quote:
Originally Posted by stuartb View Post
bummer to hear that on the launcher...i had hopes it would work also.
Don't be - the video guy says he runs 4S ... so no slow-coach power-setup
so even if he's on 3S - I bet he aint using a 20C !~!

Quote:
as far as the power in pj#2 goes,these are dons rc readings for the wicked 3000 thats installed with the 80 amp esc.

4S2250 Long Max lipo :
Prop RPM Amps Watts Pitch Speed
4.1 x 4.1 36200 rpm 35 amps 510 watts 140 mph
Larger props are not recommended on 4S, and when using 4S the motor must get good cooling.
Is that 140mph by my spreadsheet calculation ? I reckon I will be pushing 300 kph with my motor upgrade and maybe try the 4S ... First of all though is to find out what my present set-up really does if I open her up fully ! Remember my 222 kph was with restricted throttle to stop ESC burning out !

Boy oh boy - do I wanna go home and get this baby going !
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Old Feb 27, 2012, 08:28 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
2,260 Posts
Quote:
Originally Posted by solentlife View Post
Go for it .... if someone beats me - makes me all the more determined to push harder ! I'm planning on 300 kph in the next few weeks based on gear I've ordered for her.

Don't forget we need data .... motor, ESC, LiPo, weight, prop, speeds, how speeds obtained ie doppler, sensor etc. so others can benefit from our work.
WHATTTTTTTT 300km/h thats stupid for a foamy but I love it!!!!!
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Old Feb 27, 2012, 09:01 AM
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Quote:
Originally Posted by solentlife View Post
Don't be - the video guy says he runs 4S ... so no slow-coach power-setup
so even if he's on 3S - I bet he aint using a 20C !~!



Is that 140mph by my spreadsheet calculation ? I reckon I will be pushing 300 kph with my motor upgrade and maybe try the 4S ... First of all though is to find out what my present set-up really does if I open her up fully ! Remember my 222 kph was with restricted throttle to stop ESC burning out !

Boy oh boy - do I wanna go home and get this baby going !
would LOVVVVVVE to see a video of that baby doing 300, that'll be insane to say the least! yeah!
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Old Feb 27, 2012, 11:29 AM
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United States, LA, Shreveport
Joined Jun 2011
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Prop Static Thrust & More good info
http://adamone.rchomepage.com/calc_thrust.htm
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Last edited by morris.hans; Feb 27, 2012 at 11:53 AM.
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Old Feb 27, 2012, 12:13 PM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
9,133 Posts
I've read so much over last few weeks about thrust etc. and to be honest - I feel that we may be moving outside the realms of what people use for tables / discussion documents.

At high revs and loads as we have - the prop starts to do strange things ..... if you strap down my baby and open her up ... look side-on at the prop disc and you see it flex as you throttle. That is with a good quality stiff prop supposed designed for this.
Imagine that prop in the air as speed increases the flex probably decreases as NETT thrust decreases.

I daresay the mount and foam itself is suffering some small amount of deformation, witness the stress marks in photos earlier from my 222 kph run.

I fully expect to have to build up speed to the 300 kph mark in the first minute of flight, to actually launch at that level of power would be disastrous ..... To be honest - I wonder whether I need to split the attempt up - same as full-size speed record people do ... go up in stages ?

One of the problems I had on that momentous run - the cold affected my SD card in my Video machine .... the other is that the Video machine I usually use and prefer ... Sony handycam 8mm .... needs to be out in the cold for at least 20 mins to make sure it's settled to conditions.
Hopefully by time I get back in next days .... things will be OK for my next episode ! I also need a particular person who is brilliant at the videoing ... how he manages to stay on target defeats me !

All I can say is "Watch this space !! ".........
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Old Feb 28, 2012, 03:44 PM
ExPat
Aero Andy's Avatar
Spain, Murcia, Mazarrón
Joined Apr 2010
1,600 Posts
Hey Nigel

I'm going to swap my Emax 2805 2800kv motor and 3s lipo for something a little faster. I plan to take your speed record.....
Here's a photo of my new proposed set up..



I'm a little worried about the AUW, and I hope the torque isn't too much on launch...
Andy
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Old Feb 29, 2012, 12:22 AM
how'd I do that....oh
chop stiX's Avatar
South Africa, GP, Pretoria
Joined May 2011
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Quote:
Originally Posted by Aero Andy View Post
Hey Nigel

I'm going to swap my Emax 2805 2800kv motor and 3s lipo for something a little faster. I plan to take your speed record.....
Here's a photo of my new proposed set up..



I'm a little worried about the AUW, and I hope the torque isn't too much on launch...
Andy
hahahahhahahahahahahahaa
Andy you just killed me man lol that's a good idea you might have abit of as prop with AUW but sure you will figure it out
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Old Mar 01, 2012, 10:21 PM
Doug Bonham
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United States, PA, Ross Township
Joined Jul 2008
75 Posts
Quote:
Originally Posted by amba View Post
Following my PKJ's recent crash, I've decided to try and adopt some of the ideas suggested here.
Namely changing the motor angle such that thrust points to the center of the wing(rather than above wing as it used to).

I'm trying configuration 'C' in the attached drawing, achieved that by sawing the stick that came with the kit (and survived the first crash) to give the motor the needed down angle.

Hopefully, tomorrow it'll fly (at least, we'll know if this does the trick or not )
I was actually going to suggest adding some downward thrust.... should help with the hand launching.
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Old Mar 01, 2012, 10:29 PM
Doug Bonham
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United States, PA, Ross Township
Joined Jul 2008
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Quote:
Originally Posted by WickedDragon View Post
Why thank you! That's the nicest thing anyone's said to me today!!! Ah cumon... a 3:1 thrust to weight ratio, isn't that outrageous.... is it?? Which reminds me... anyone have an average flying weight on this bird? It's only a 56mm fan.

Here are the specs....
Motor 24-45-3790
s V A W Thrust rpm eflux speed (mph)
3 11.1V 19.9A 221W 450g (15.9oz) 38,600 135.89~
4 14.8V 32.6A 482W 721g (25.4oz) 48,000 217.73~

(You'll have to figure out the headings yourselves... they just won't line up!)

So about 1.6 lbs of static thrust, but I think that's very conservative... thinking more like 2+ and pushing air at 218mph.

I'm going to try to get some real thrust number over the next couple of days... after I figure out how I'm going to do that. Unfortunately, as I said the thrust line ended up slightly skewed, but it will still rock! Hopefully, I'll be able to get someone to Doppler it and get an actual speed... not sure if the radar gun will work with so little metal!
With these crazy speed run results, I'm not sure this is even worth mentioning... But, finally got to test on a 4s pack..... it's bumping 30oz of thrust.... beat the specs by 5oz... might be able to tweak out another ounce or two with motor timing! Might actually have to put a good ESC on this critter..... and yes Taz is getting anxious for the maiden! Our field is very swamp like currently!
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Last edited by WickedDragon; Mar 13, 2012 at 01:17 PM.
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Old Mar 03, 2012, 10:10 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia, Ventspils pilsēta, Ventspils
Joined Jan 2010
9,133 Posts
Just to let all know - I'm on my way home for a few days from the desert ....

So if weather is good - yer better watch out ! I'm all out to beat my own record ...

Remember peeps ... watts is good but you have top get it into a high pitch propellor to generate speed ... it's no good having loads of thrust and a prop that cops out ...

Think about the Tug boat in port - loads of thrust but no speed.
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