Wattflyer RC Network: RC Universe :: RCU Magazine :: RCU Forums :: RCU Classifieds :: RCU User Reviews :: RCU YouTube
Home Who's Online Calendar Today's Posts RealTime Post Spy Mark Forums Read
Go Back   WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Electric Ducted Fan Jets
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

Electric Ducted Fan Jets Discuss electric ducted fan jets here including setup tips, power systems, flying techniques, etc.

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 10-06-2014, 09:57 PM   #1
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default EDF Thrust Meter

Does anyone have the HK type thrust tester? Can you also put the nose of the jet against it and check the static thrust of the jet? Any other suggestions for a thrust tester?

Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Old 10-06-2014, 10:48 PM   #2
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 6,222
View solentlife's Gallery47
Thanked 266 Times in 263 Posts
Club: Founder Member Ventspils RC Club. Ex Waltham Chase and Meon Valley Soaring.
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Outstanding Contributor Award  125mph Speed Demon 
iTrader: (0)
Friends: (15)
Default

I just place standard kitchen digital scale on floor. Switch on, stand model on scale by its nose. Zero weight and then open throttle .... model pushes down on scale reading thrust only with no losses or friction.

Simple, only needs a cheap scale.

Nigel

222kph PKJ,EDF Concorde, Mini4,Mig3,T45,PKJ twin,ME109,Edge540,Cessna182,Skymaster Biplane,F15,F16,Badius,Ultimate,SE5,Qbee10,450 Heli,V911,J3 Cub Founder 9x forum: http://groups.yahoo.com/group/Flysky_RC_radio/
- Subscribe my Youtube: "solentlifeuk"
solentlife is online now  
  Reply With Quote
Old 10-06-2014, 10:50 PM   #3
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 4,495
Thanked 492 Times in 458 Posts
Awards Showcase

5kW  Outstanding Contributor Award  1kW 
iTrader: (0)
Friends: (8)
Default

All you need is a weight scale with the range to cover your expected thrust. Digital 'spring balance' hanging type is ideal, can be picked up for next to nothing off ebay. If the plane has wheels just hook the spring balance on the tail give it full throttle and see how hard it puls. If the plane doesn't have wheels hang it from a roof beam or similar, zero the scales and see how hard it pulls down when you give it throttle.

Or if the weight of the plane and thrust combined wont overload them, use standard kitchen scales as suggested above.

There is no great science to it.
JetPlaneFlyer is offline  
  Reply With Quote
Old 10-06-2014, 11:24 PM   #4
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default

Thanks for the great advice. I will give it a try. Any ideas how to test with the unit out of the plane?

Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Old 10-07-2014, 12:01 AM   #5
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 2,246
Thanked 223 Times in 214 Posts
iTrader: (0)
Friends: (1)
Default

Simple thrust measuring devices work fine for EDF just as with the prop planes... but an EDF is a strange beast. Most will "stall" the fan if there's low/no airspeed at high throttle.

There's simply a maximum differential pressure you can develop between the front and back of the EDF. A good inlet ring, eflux tube and ducting system can improve things, but you'll still only be measuring the static thrust. which my experimenting (mostly I tie a fish scale to the tail of the planes) shows that peak static thrust is usually 50% to 75% throttle.

My big EDF in the Avatar pic gets off the ground in 100 ft less runway at half throttle vs hammering it to full from a standstill...

Your data from trying to measure static thrust of a bare fan may have absolutely no relationship to how the aircraft will perform.
fhhuber is online now  
  Reply With Quote
Old 10-07-2014, 12:26 AM   #6
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default

Thanks! That makes perfect sense. I fly the Freewing 64 mm jets. I guess that explains why they struggle after launch but accelerate once they get moving.

Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Old 10-07-2014, 06:58 AM   #7
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 4,495
Thanked 492 Times in 458 Posts
Awards Showcase

5kW  Outstanding Contributor Award  1kW 
iTrader: (0)
Friends: (8)
Default

Measuring the thrust of an EDF out of the plane can have little correlation to what thrust it will make when mounted internally inside ducting. The ducting usually reduces thrust significantly. Also small details like the presents and shape/size of an inlet 'bell-mouth' make a huge difference to static thrust, but less difference in flight. So it's complicated.
JetPlaneFlyer is offline  
  Reply With Quote
Old 10-07-2014, 08:59 AM   #8
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 6,222
View solentlife's Gallery47
Thanked 266 Times in 263 Posts
Club: Founder Member Ventspils RC Club. Ex Waltham Chase and Meon Valley Soaring.
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Outstanding Contributor Award  125mph Speed Demon 
iTrader: (0)
Friends: (15)
Default

So far my EDF;s have shown about 15 - 30% reduction in thrust OUT and IN a model.

My 70mm's being the worst ... and the 50mm being the best.

I used to hang my models from house beam on a Fishermans scale - this is way I do it with tractor Prop models ... but EDF's - I now simply stand on nose on kitchen scale ...

Static Thrust may not be same as Dynamic In-Flight - but it is a good indicator of good or bad installation.

Test of EDF out of model is a waste of time really as results are not related to airframe issues. An example is a Hobby King 70mm EDF can produce over 1200gr's static thrust out of airframe ... but is stifled to a measly 900gr installed. (70mm Haoye EDF, 2800KV, 4S LiPo). Even upping to a 5S doesn't really make much difference as the restriction is the airframe ducting.

Nigel

222kph PKJ,EDF Concorde, Mini4,Mig3,T45,PKJ twin,ME109,Edge540,Cessna182,Skymaster Biplane,F15,F16,Badius,Ultimate,SE5,Qbee10,450 Heli,V911,J3 Cub Founder 9x forum: http://groups.yahoo.com/group/Flysky_RC_radio/
- Subscribe my Youtube: "solentlifeuk"
solentlife is online now  
  Reply With Quote
Old 10-07-2014, 12:04 PM   #9
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default

Thanks to everyone for the information. I have 3 Freewing jets and used to sell ELE EDF units on our web site. I have many fans 5, 6, & 8 blades. Several motors various Kv. I was playing mix 'n match but wanted a way to get in the ball park for amps/thrust before driving 30 miles to the field.

Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Old 10-07-2014, 12:22 PM   #10
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 2,246
Thanked 223 Times in 214 Posts
iTrader: (0)
Friends: (1)
Default

Basic rule is 50% more watts/lb than what is needed for the same performance with a good pusher prop setup.

Because of this, to hit the same weight, we generally accept shorter flight time with EDF to get the desired performance.

That's assuming you are comparing to a high rpm pusher and aiming at level flight top speed. Also EDFs tend to lose speed in tight turns.
My Dynam Me262, for example, can fly circles around a local guy's big P-61 if I keep the turns wide... If I try to make the same tight turns he does at the end of each lap he's got me every time.
fhhuber is online now  
  Reply With Quote
Old 10-07-2014, 12:46 PM   #11
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default

I have never had a pusher and am not trying to set a speed record. I have flown pylon planes (still have a Cosmic Wind) that go well over 140 mph. I just like to tinker, experiment, and go fast. Just started playing with the foam jets and having a blast with "something new".

Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Old 10-14-2014, 05:30 PM   #12
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default Thrust stand

I put together a thrust test stand with stuff I had laying around. The jet sits on the white board that is mounted to the bottom board with high quality ball bearing drawer slides. It moves glass smooth with zero drag. The front of the sliding board is pointed and pushes against a digital scale. I can wind it up hands free and test amps, volts, watts, and thrust. The stock 4 cell Stinger I read 32.3 A, 14.7 V, 460 watts, and 21 oz thrust. It will be interesting to see what the hot set ups are when they arrive. May not mean much in actual flying but I like to tinker.


Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Old 10-19-2014, 11:29 PM   #13
Bill G
Super Contrubutor
 
Bill G's Avatar
 
Join Date: Oct 2005
Location: West Central PA
Posts: 4,300
View Bill G's Gallery86
Thanked 177 Times in 171 Posts
Club: rcg staff
Awards Showcase

Outstanding Contributor Award  Outstanding Contributor Award  Scratchbuilders Award 
iTrader: (3)
Friends: (17)
Default

Some years ago I made a foam mount that would cradle a fuselage and clip onto a postal scale. Very crude, but a better version could easily be made. The good thing with analog is that you can slight variations and still deduce a good reading. With digital, it has to reach a steady state or the readings are either all over the place, if you can even get any reading at all.


Attached Thumbnails
Click image for larger version

Name:	ME262_large_foamie8_thrust.JPG
Views:	20
Size:	52.0 KB
ID:	177968  
Bill G is offline  
  Reply With Quote
Old 10-21-2014, 01:23 AM   #14
SlickZERO
Member
 
SlickZERO's Avatar
 
Join Date: Jan 2006
Location: Citrus Springs, Florida
Posts: 95
Thanked 0 Times in 0 Posts
Club: Nature Coast R/Cers
iTrader: (0)
Friends: (0)
Default

Seems to work fine. I guess the sliding tray has enough mass to keep it steady? I rev it up and when the scale peaks I push the hold button. I try it several times and get the same reading until the battery voltage starts to drop.

Too many projects, Too little time
Bret Martin
SlickZERO is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Electric Ducted Fan Jets

« Previous Thread | Next Thread »

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
AEO 27mm EDF thrust not there jibwalker Electric Ducted Fan Jets 44 03-22-2014 12:33 AM
JPower 50mm EDF V-Tail Jet Glider Joe 1320 Electric Ducted Fan Jets 4 06-03-2013 03:53 PM
ELERC Micro A-10 Warthog 30mm EDF Beta Test Joe 1320 Electric Ducted Fan Jets 13 02-02-2012 02:15 PM
Home made thrust vectoring nozzles for EDF? earthsciteach Electric Ducted Fan Jets 6 10-06-2011 12:03 PM
Prop Selection Hose Man Beginners 7 03-23-2011 02:57 PM


All times are GMT +1. The time now is 09:27 PM.


Powered by: vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Charities we support Select: Yorkie Rescue  ::  Crohn's & Colitis Foundation



Page generated in 0.27807 seconds with 50 queries