SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Mar 07, 2010, 05:54 AM
Extreme CNC Alloy EDF
Extreme_RC's Avatar
Australia
Joined Mar 2006
11,578 Posts
Quote:
Originally Posted by maxsky View Post
Happy that my thought were confirmed by the holly rc bible

By the way coul you tell us if he can add the thrust of each motor on a twin edf jet to calculate the final thrust power?
Certainly you can add the thrust of two fans to see your total static output, best to try and do it with the fans in the installation so all losses are taken into consideration.
Extreme_RC is offline Find More Posts by Extreme_RC
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 07, 2010, 11:26 AM
Registered User
Joined Jan 2010
78 Posts
Kind a strange thing cause freewing is rating is motors for 1100 Gr of thrust so if we add them together it should gives 2200 Fr of thrust

I never see someone getting 2.2 Kg of thrust with these things.

3500 Kv stock Freewing motor gives me 1.5 Kg of thrust.

I will receive the 3800 Kv version next week so i will test it and keep you informed but i am sure that i will get something like 1.8 Kg of thrust like everybody does....
maxsky is offline Find More Posts by maxsky
Reply With Quote
Old Mar 08, 2010, 12:01 AM
Extreme CNC Alloy EDF
Extreme_RC's Avatar
Australia
Joined Mar 2006
11,578 Posts
Its called losses, testing the fan and motor on a thrust stand with perfect inlet and outlet gives 1100g thrust for one fan on a single battery pack with high C ratings.

Put 2 together inside the fuse, the answer is simple
Extreme_RC is offline Find More Posts by Extreme_RC
Reply With Quote
Old Mar 08, 2010, 02:01 AM
Registered User
Joined Jan 2010
78 Posts
Good answer, we both agree with this

I always told that raw spec can t be added together to give your final thrust.
I didn't know that it was only due to loss but now I am sure that mfg company are giving their thrust under the best conditions wich never occurs by the way
maxsky is offline Find More Posts by maxsky
Reply With Quote
Old Mar 08, 2010, 12:23 PM
Registered User
hklagges's Avatar
Munich
Joined Dec 2008
1,145 Posts
Quote:
Originally Posted by Mtn_Commando View Post
Had to move the ball joint of one of the nozzles to the other side to make both nozzles operable by a single TV yaw servo.
I did so, too.

Quote:
total of 7200mahs at a combined weight of 780 grams.
Too heavy in my book, I told you at least 3 times, I think .

Quote:
heavy 150+ gram rx battery and just go with a 7A UBEC,
7A sound good.

Quote:
I really hate the fact that edfs have such little flight time
I fly my Su-34 for 8 minutes on 3.200 mAh, but very easy on the throttle (40%) and with the "optimized" airflow. It seems to me that the very short flight times only happen if you fly full throttle.

Cheers,
Henrik
hklagges is offline Find More Posts by hklagges
Reply With Quote
Old Mar 08, 2010, 12:43 PM
Registered User
Mtn_Commando's Avatar
United States, CA, Dublin
Joined Sep 2008
1,007 Posts
Quote:
Originally Posted by hklagges View Post
Too heavy in my book, I told you at least 3 times, I think .
Yes definitely not light. I'm hoping that moving the packs far back will help, along with the heavy k-force esc's (82 grams a piece). If I can't make the cog work, I'll go for lower mah packs.

Can you please share how much your pack weighs, where you have it situated, and how much (if any) weight you had to add aft to make it balance?


Quote:
Originally Posted by hklagges
I fly my Su-34 for 8 minutes on 3.200 mAh, but very easy on the throttle (40%) and with the "optimized" airflow. It seems to me that the very short flight times only happen if you fly full throttle.

Cheers,
Henrik
Yes i definitely won't be flying full throttle for most of the flight duration. 8 minutes is much nicer. But still lower than 15 mins which glow and low amp electrics can achieve without breaking a sweat. What is your amp draw at 40% throttle?
Mtn_Commando is offline Find More Posts by Mtn_Commando
Reply With Quote
Old Mar 09, 2010, 07:57 PM
Registered User
United States, FL, Fort Pierce
Joined Jan 2007
194 Posts
Extreme RC

Earlier you said that you'd start work on the F-35. Have you started work on it yet? Do you have a build thread? I'm hoping that they avoided some of the issues that has been pointed out on the su-47.
truevine77 is offline Find More Posts by truevine77
Reply With Quote
Old Mar 10, 2010, 12:19 AM
Extreme CNC Alloy EDF
Extreme_RC's Avatar
Australia
Joined Mar 2006
11,578 Posts
F35 looks to be very different, its much lighter to start with, I think the retracts will be quite good in this model just due to the weight reduction. I havent had a chance to assemble one but I will try and get to it in the next few weeks, lots of other building that needs to be done right now and hard to find time! Am hoping the controls are not all pre linked so we dont have to change the ext leads around, but until I get into it and check no point guessing
Extreme_RC is offline Find More Posts by Extreme_RC
Reply With Quote
Old Mar 12, 2010, 11:28 AM
Registered User
hklagges's Avatar
Munich
Joined Dec 2008
1,145 Posts
Lack of flight reports

Hello there,

I am curious that there are still so few flight reports.

[ ] Do only a few people have the Su-47?
[ ] Do only fewer people have finished the build?
[ ] Did they crash their model and abandon it?
[ ] Is the weather friggin freezing everywhere on this planet like here?
[ ] Does it fly bad and was a disappointment and nothing to report about?
[ ] None of the above

Cheers,
Henrik
hklagges is offline Find More Posts by hklagges
Reply With Quote
Old Mar 12, 2010, 06:18 PM
Registered User
Bigdaddi's Avatar
north east pa
Joined Nov 2009
70 Posts
You forgot shelf decoration, Really Big shelf decoration.
Bigdaddi is offline Find More Posts by Bigdaddi
Reply With Quote
Old Mar 12, 2010, 06:21 PM
Registered User
Mtn_Commando's Avatar
United States, CA, Dublin
Joined Sep 2008
1,007 Posts
Quote:
Originally Posted by hklagges View Post
Hello there,

I am curious that there are still so few flight reports.

[ ] Do only a few people have the Su-47?
[ ] Do only fewer people have finished the build?
[ ] Did they crash their model and abandon it?
[ ] Is the weather friggin freezing everywhere on this planet like here?
[ ] Does it fly bad and was a disappointment and nothing to report about?
[ ] None of the above

Cheers,
Henrik
Well mine is still under construction, maiden should be about 2 weeks away.

Can you please share how much your pack weighs, where you have it situated, and how much (if any) weight you had to add aft to make it balance?
Mtn_Commando is offline Find More Posts by Mtn_Commando
Reply With Quote
Old Mar 12, 2010, 06:51 PM
Registered User
Bigdaddi's Avatar
north east pa
Joined Nov 2009
70 Posts
I'm just waiting for some good weather to maiden mine.
Bigdaddi is offline Find More Posts by Bigdaddi
Reply With Quote
Old Mar 13, 2010, 06:15 AM
Registered User
hklagges's Avatar
Munich
Joined Dec 2008
1,145 Posts
Quote:
Originally Posted by Mtn_Commando View Post
Can you please share how much your pack weighs, where you have it situated, and how much (if any) weight you had to add aft to make it balance?
I bought the Turnigy 6s 30C 3600mAh. It weighs 577gs and has (according to the manufacturer) a size of 137 x 43 x 43mm. This geometry allows me to push the pack far back into the head, it goes so far back that the velcro strap doesn't cover it anymore. I didn't put any weight at the back of the plane on purpose, but of course I have 2 servos more for the TV nozzles. Also, I am not using the parachute at this moment, so its weight is not there as a counterbalance at the back. Even so, I put a Schulze LiPoRXII 910.7 receiver battery into the front to make the plane balance at an adjusted COG plus 10mm. The battery can do 7A continuous at a controlled voltage - better than relying on one 3A continuous ESC. It weighs another 77g.

Regarding the Turnigy: My first test pack died after one test run... Turnigy Death.

Cheers,
Henrik
hklagges is offline Find More Posts by hklagges
Reply With Quote
Old Mar 13, 2010, 01:48 PM
Registered User
Mtn_Commando's Avatar
United States, CA, Dublin
Joined Sep 2008
1,007 Posts
Quote:
Originally Posted by hklagges View Post
I bought the Turnigy 6s 30C 3600mAh. It weighs 577gs and has (according to the manufacturer) a size of 137 x 43 x 43mm. This geometry allows me to push the pack far back into the head, it goes so far back that the velcro strap doesn't cover it anymore. I didn't put any weight at the back of the plane on purpose, but of course I have 2 servos more for the TV nozzles. Also, I am not using the parachute at this moment, so its weight is not there as a counterbalance at the back. Even so, I put a Schulze LiPoRXII 910.7 receiver battery into the front to make the plane balance at an adjusted COG plus 10mm. The battery can do 7A continuous at a controlled voltage - better than relying on one 3A continuous ESC. It weighs another 77g.

Regarding the Turnigy: My first test pack died after one test run... Turnigy Death.

Cheers,
Henrik
Thanks for sharing. It's interesting that you had to add the rx battery weight to the FRONT. I'm thinking I'll have the opposite problem with the heavy batteries that I plan to use. You could have used an external BEC and used the weight saving to put in a bigger pack
Mtn_Commando is offline Find More Posts by Mtn_Commando
Reply With Quote
Old Mar 13, 2010, 04:13 PM
Registered User
hklagges's Avatar
Munich
Joined Dec 2008
1,145 Posts
Hello there,

Quote:
Originally Posted by Mtn_Commando View Post
It's interesting that you had to add the rx battery weight to the FRONT.
Initially, I thought I would use the standard tv nozzles, which are lighter, and the standard tv setup, which does not require the 2 extra servos that I put in at the rear. I also bought extra light lipos because I made the mistake of oversizing a battery for the Su-34.

Quote:
I'm thinking I'll have the opposite problem with the heavy batteries that I plan to use.
Yes .

Quote:
You could have used an external BEC and used the weight saving to put in a bigger pack
I thought about that, and I also asked my ESC manufacturer whether their BECs could be used in parallel, which unfortunately, they can't. But after the Turnigy battery pack died after its first test run in my living room, I thought that maaaybe after all this work that I put into the Su-47, I want to have control over the steering surfaces independently of the main battery... so that I could still sail it down to earth even if the main battery dies.

Cheers,
Henrik
hklagges is offline Find More Posts by hklagges
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product FreeWing 70mm F-35 w/ Thrust Vectoring bhatch21 Foamy EDFs 1411 Yesterday 10:48 AM
Discussion F-22 Raptor thrust vectoring scratch built twin ducted fan jet MikeysRC Foamies (Scratchbuilt) 2 Aug 05, 2009 11:29 AM
Discussion SU-35 or any twin EDF with thrust vectoring dash8pilot Electric Ducted Fan Jet Talk 11 Jul 21, 2008 07:32 AM
Discussion Wicked thrust vectoring twin turbine mig-29 video lavochkin Foamy EDFs 5 Jun 12, 2008 12:07 PM
Build Log Mig-35 Twin EDF w/ Thrust Vectoring tailslide5_0 Foamy EDFs 23 Aug 27, 2007 09:20 PM