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Old Feb 20, 2012, 07:23 AM
TheThomass is offline
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doppler


Hi guys in case one of you know how to measure the speed :-)
http://youtu.be/y8laB0hcUWQ
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Old Feb 20, 2012, 09:41 AM
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Quote:
Originally Posted by TheThomass View Post
Hi guys in case one of you know how to measure the speed :-)
I just used an iPhone app called RCSpeedo and held it up to the speakers. You have to choose high quality video on youtube for this to work well.

Time in video 0:35, speed 66 mph (106 kph)
Time in video 0:55, speed 62 mph (99 kph)
Time in video 1:04, speed 75 mph (121 kph)

This seems about right, I use the same motor and prop as you, but run mine on 3S and have clocked it around 130-140 kph.
Old Feb 20, 2012, 11:40 AM
Aero Andy is offline
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Quote:
Originally Posted by meshyx View Post
I just used an iPhone app called RCSpeedo and held it up to the speakers. You have to choose high quality video on youtube for this to work well.

Time in video 0:35, speed 66 mph (106 kph)
Time in video 0:55, speed 62 mph (99 kph)
Time in video 1:04, speed 75 mph (121 kph)

This seems about right, I use the same motor and prop as you, but run mine on 3S and have clocked it around 130-140 kph.
Hi meshyx

That's a brilliant app, please could you have a go at my video below, I'd really appreciate it.
Many thanks
Andy

HobbyKing Park Jet (2 min 34 sec)
Old Feb 20, 2012, 11:41 AM
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Quote:
Originally Posted by meshyx View Post
I just used an iPhone app called RCSpeedo and held it up to the speakers. You have to choose high quality video on youtube for this to work well.

Time in video 0:35, speed 66 mph (106 kph)
Time in video 0:55, speed 62 mph (99 kph)
Time in video 1:04, speed 75 mph (121 kph)

This seems about right, I use the same motor and prop as you, but run mine on 3S and have clocked it around 130-140 kph.
Wow , I estimated it around 60-70kph.
So it's a lot faster than I thought. It's time for some 3s lol

Important note: there was wind, but for people not into RC it's cooler to say it goes 120kph

I don't have an iPhone so thanks a lot for this!
Old Feb 20, 2012, 01:11 PM
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Quote:
Originally Posted by Aero Andy View Post
That's a brilliant app, please could you have a go at my video below, I'd really appreciate it.
For the passes around 1:10 and 1:20 I got 104 and 109 kph (65 and 68 mph)

I don't want to take over this thread with more speed readings, so everyone who are curious should take a look at http://www.rcspeedo.info , they have a free version for PC, and cheap ones for iPhone and android phones.
Old Feb 20, 2012, 01:34 PM
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To cheer some of you up: even I crash "sometimes" lol
http://www.youtube.com/watch?v=4rxDOlZQBhI

also broke the prop on another flight

Tomorrow next flight with onboard cam so hopefully I'll be able to put some footage on YT

@meshyx: completely understandeable Thanks for the link, I'm downloading it right away!

Grtz, Thomas
Last edited by TheThomass; Feb 20, 2012 at 01:58 PM.
Old Feb 20, 2012, 07:06 PM
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I use the PC version a lot ... particularly checking out Youtube claims ! Less said about that !!

What I would like to see is a data set .... what motor kv, what Lipo ie 1300 3S 25C, what prop ........ against the speeds obtained. This way it becomes really useful info for others ....

Lets take mine for example :

3700kv motor, 5x5 prop, 3S 1300mAh 25C lipo, throttle EPA set at max 30Amps gave me a speed of 222kph measured by on-board EagleTree Sensor.

With regard to RCSpeedo ... I have real trouble getting Android version to install ... I want to pay .. I want to support author ... but my Android 2.3.4 phone is refused by Apps market install routine. Reason I am told is many apps are brand specific and mine is not covered. I contacted RCSpeedo but no reply.
Old Feb 20, 2012, 11:29 PM
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i just put a 4s 1300 45-90c nano on my turnigy typhoon 3450kv motor. it screammms on 90% throttle...... so addictive
Old Feb 21, 2012, 03:01 AM
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My setup and speed (RCspeedo on PC)

2730 3000kv motor, 30A ESC, 4.75x4.75, 2s 1000mAh lipo, 250g

0:28 - 131,6 KPH
0:36 - 103,3 KPH
0:43 - 77,5 KPH
0:55 - 107,9 KPH
0:56 - 88,8 KPH
1:21 - 81,8 KPH
1:25 - 75,5 KPH
2:13 - 199,8 KPH
2:20 - 117,0 KPH
2:42 - 136,7 KPH
2:48 - 96,1 KPH
2:58 - 90,5 KPH
3:13 - 107,1 KPH
3:20 - 124,5 KPH
3:37 - 98,8 KPH

(video is a few posts higher: Parkjet doppler passes)
Old Feb 21, 2012, 05:08 AM
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222 km/hr Parkjet flyer
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Quote:
Originally Posted by TheThomass View Post
To cheer some of you up: even I crash "sometimes" lol
http://www.youtube.com/watch?v=4rxDOlZQBhI

also broke the prop on another flight

Tomorrow next flight with onboard cam so hopefully I'll be able to put some footage on YT

@meshyx: completely understandeable Thanks for the link, I'm downloading it right away!

Grtz, Thomas
Ever thought to turn the mount round and have prop closer to back of model ? May help with any CoG so you can try out various different packs ....

Looking at later Doppler speed results .... the 199 kph ... seems out of place .. did you have a full throttle dive at any time ? Watching the video - you obviously static mounted the camera to pick up the sound ... the fly-pasts are quick - but having flown mine at 222 kph ... appear slower ...

Stick a 3S in there - you know you want to !! I have a 4S ready to go in ... WHEn I get back home again ..........
Old Feb 21, 2012, 05:15 AM
dusk is offline
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My setup and speeds:

Hextronik 24g 3000kv motor, 4.5x4.5E prop, 3S 1300mAh 25C lipo,
30Amp ESC, 20Amp (225W) peak, 355gAUW, speed by RCSpeedo

155.0km/h
156.9km/h
163.1km/h

HXT900 servos. 95% success rate launching with a side arm toss at 50% throttle.
Last edited by dusk; Feb 22, 2012 at 05:26 AM.
Old Feb 21, 2012, 06:39 AM
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If people don't mind - I want to start a spreadsheet of motors / ESC / power etc. to detail these machines ...

It will be interesting to compare set-ups.

Nigel
Old Feb 21, 2012, 07:05 AM
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Checking through various forums etc.

It seems that on 2S - you can expect from 100 - 120KPH realistically .... depending on kv of course and I'm assuming people using 2700 - 3100.

On 3S that jumps to 120 - 160kph on same motor.

An interesting item .. what is the LOWEST kv and set-up people have flown the PKJ with ? Results ? I tried with 1800kv and 3S ... gave 8.7A and 110W ... but flopped on launch .. now we know that trim was terribly out and may have prevented flight.

For results table ,.... really interested in :

Motor Brand name
kv
ESC amp size
LiPo data - that is S, mAh , C
Speeds in KPH or MPH (please say which)
Method of speed determination ... Pitot, radar, doppler, GPS ...
All up weight in grams or ozs (please say which)

Lets put together worthwhile info ....

Once I have a reasonable number of entries - I'll make available to anyone who wants it.

If you want to send direct to me the info ... then PM or email - fine.

Cheers
Nigel
Old Feb 21, 2012, 07:24 AM
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hey this rcspeedo app is cool! i ran it on my video and it gave me the following results

Hobby King Park Jet Mk 2 (7 min 11 sec)




Neat! Mine is the stock setup of the mk2, running an 800mah turnigy 3s with a 4.5x4.5 prop.

Thanks for the rcspeedo link!
Old Feb 21, 2012, 07:30 AM
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I finally managed to launch mine consistently. I use a left handed discus throw with the thumb on the underside. I've used it with a lot of small wings before, but had a lot of trouble with this one.

Thank god for the half meter of snow, I estimate about 20 crashes and five successful launches in the last few weeks Turns out that the trick is to give about 1/3 throttle and 1/3 right stick during the launch, that resulted in a very smooth transition.

I'm using the standard 24gram 3000kv motor on a low stick mount with a 1000 mah 3S battery.


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