HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 27, 2012, 10:13 AM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
21,866 Posts
how did you guys attach the servo? i siliconed mine in.
corsair nut is online now Find More Posts by corsair nut
Reply With Quote
Sign up now
to remove ads between posts
Old May 27, 2012, 11:07 AM
Registered User
United States, TN, Jackson
Joined Mar 2007
4,011 Posts
GREAT JOB, Extreme!!!...Now THIS is a properly designed stab not prone to flutter!!!...With the other design the aerodynamic forces are going to try to make the tips flutter...You are relying on the combined strengths of the structure/servo/control linkage to prevent flutter...Why not do as Extreme has done and design a stab/elevator assembly the is more neutral aerodymanically, providing less strain on all of the parts???...The parts get built with lighter components as the structure doesn't need to be overbuilt to keep from destroying itself in flight...Looks GREAT to me!!!...

Kevin
Kevin Greene is offline Find More Posts by Kevin Greene
Reply With Quote
Old May 27, 2012, 12:16 PM
Callsign blocked
Brickyard's Avatar
United States, NY, New York
Joined Dec 2008
223 Posts
Quote:
Originally Posted by Kevin Greene View Post
GREAT JOB, Extreme!!!...Now THIS is a properly designed stab not prone to flutter!!!...With the other design the aerodynamic forces are going to try to make the tips flutter...You are relying on the combined strengths of the structure/servo/control linkage to prevent flutter...Why not do as Extreme has done and design a stab/elevator assembly the is more neutral aerodymanically, providing less strain on all of the parts???...The parts get built with lighter components as the structure doesn't need to be overbuilt to keep from destroying itself in flight...Looks GREAT to me!!!...

Kevin
Not trying to start anything, but I'm very unclear as to why you guys want to go with a completely different design than today's successful sport jets? Bandit, Electra, futura, ultra flash/lightning/spark..etc, etc.. I don't get it
Brickyard is offline Find More Posts by Brickyard
Reply With Quote
Old May 27, 2012, 01:05 PM
Team EJF >>>WHOOSH>>>
AceMigKiller's Avatar
Joined Jul 2004
5,256 Posts
Quote:
Originally Posted by Tamjets View Post
Vic,
I never wrong and know what goes to happen with this design and just most other had the experience like I do.
DUDE!
I almost spat up my coffee when I read this!!!

I'm sorry buddy, I know you think you're hot stuff and all but you're no real "master"... just another guy with an opinion. I think just about everybody here has seen you make mistakes both verbally and on the flightline.

Oh man! That was a good one... thanks for the laugh Tam

Vic
AceMigKiller is offline Find More Posts by AceMigKiller
Reply With Quote
Old May 27, 2012, 01:13 PM
3DHOG
jcdfrd's Avatar
USA, CA, Aromas
Joined Sep 2010
4,847 Posts
Quote:
Originally Posted by corsair nut View Post
how did you guys attach the servo? i siliconed mine in.
good morning Brent
nick used hs 5085's throughout and the dimensions of that servo made it a snug fit in the elevator and too keep the control horn centered on the elevator he removed some of the mounting hardware block that the bolt goes thru to be able to slide the servo into the stab more and get a straight perpendicular shot to the elevator control horn. what this did was create a sandwich effect when the mounting the stab, 75% of the servo was covered by the stab skin and then the fuse skin when installed and when you tighten down the stab bolts it also clamped the servo in place. it was taped and glued (potted) to the bottom of the elevator skin as instructed in the manual but now after a 3hr ride home and discussing the failure and stopping occasionally to pull parts and inspect them, Nick is kicking himself a little for not epoxying all the way around the servo and the bottom against the wood block that would have helped but I think his install was good. the problem is when you have a bad design that creates weaknesses and then try to strengthen the weaknesses(better hinges and gap sealing) the failure point just moves down the line. in our case it was the servo mount. a normally good enough mount turned out not good enough for this design
jcdfrd is offline Find More Posts by jcdfrd
Reply With Quote
Old May 27, 2012, 01:15 PM
Team EJF >>>WHOOSH>>>
AceMigKiller's Avatar
Joined Jul 2004
5,256 Posts
Guys,
It's abundandtly clear that it's my belief there is no flutter coming off the tail.
Aerodynamic theory is great (I have a degree in the stuff, as many others do), but you just can't disprove real-world data. I have already stated that this Stab/Elevator design is not the most *optimal* design, but the hard fact is we're simply not generating enough force to cause aerodynamic flutter!
I don't care to calculate what the theoretical number is when we reach the critical point.
We have Brent's and My Sniper flying now (on video) making high speed passes with no hints of flutter... and we're not being easy on them either
Even when the Prototype of this model crashed, there was no flutter... the entire Elevator simply ripped out due to my hinges not being glued in properly.

If you guys want a Split-Elevator design, that's fine.
We've already formulated a plan to work towards that. But a Split-Elevator isn't going to help you if you still don't glue in your hinges properly!!! Except maybe one Elevator will come off and not the other... who knows.

You can build your Sniper XL90 correctly, right now, and fly just like mine and Brent's did in the video. Unless there's some aerodynamic theory I'm unaware of that can prove I actually wasn't there and ours Snipers didn't really fly.


Vic
AceMigKiller is offline Find More Posts by AceMigKiller
Reply With Quote
Old May 27, 2012, 02:01 PM
Registered User
alanjets's Avatar
Ripoff britain
Joined Jan 2011
229 Posts
Quote:
Originally Posted by AceMigKiller View Post
Guys,
It's abundandtly clear that it's my belief there is no flutter coming off the tail.
Aerodynamic theory is great (I have a degree in the stuff, as many others do), but you just can't disprove real-world data. I have already stated that this Stab/Elevator design is not the most *optimal* design, but the hard fact is we're simply not generating enough force to cause aerodynamic flutter!
I don't care to calculate what the theoretical number is when we reach the critical point.
We have Brent's and My Sniper flying now (on video) making high speed passes with no hints of flutter... and we're not being easy on them either
Even when the Prototype of this model crashed, there was no flutter... the entire Elevator simply ripped out due to my hinges not being glued in properly.

If you guys want a Split-Elevator design, that's fine.
We've already formulated a plan to work towards that. But a Split-Elevator isn't going to help you if you still don't glue in your hinges properly!!! Except maybe one Elevator will come off and not the other... who knows.

You can build your Sniper XL90 correctly, right now, and fly just like mine and Brent's did in the video. Unless there's some aerodynamic theory I'm unaware of that can prove I actually wasn't there and ours Snipers didn't really fly.


Vic
I think Vic is right the planes arnt going fast enough to cause it to flutter mine wasnt glued it the wood there wasnt any there lol it was in the wrong place and it just riped the ones that were in out. its on the elivator i still have, the end ones just torn apart.I used Polycarbonate car body sealant the one thats used to glue car body pannels on to fix the servo in i dont even tape them a nightmare to get out but u do it right the first time
alanjets is offline Find More Posts by alanjets
Last edited by alanjets; May 27, 2012 at 02:26 PM.
Reply With Quote
Old May 27, 2012, 03:05 PM
Robert Wagoner's Avatar
Tucson, Arizona, USA
Joined Dec 1999
1,552 Posts
Wind tunnel testing

I'm going to arrange at the local UofA Aerospace lab for us to bring over a functional elevator assembly to be run in the wind tunnel. Then we can get this figured out once and for all on the existing details of dynamics and potential redesign of control surface design and shape.

--RW
Robert Wagoner is offline Find More Posts by Robert Wagoner
Site Sponsor
Reply With Quote
Old May 27, 2012, 03:15 PM
More Speed Indeed!
Hossinarizona's Avatar
USA, AZ, Tucson
Joined Nov 2007
1,012 Posts
Quote:
Originally Posted by Robert Wagoner View Post
I'm going to arrange at the local UofA Aerospace lab for us to bring over a functional elevator assembly to be run in the wind tunnel. Then we can get this figured out once and for all on the existing details of dynamics and potential redesign of control surface design and shape.

--RW
Mine
Hossinarizona is offline Find More Posts by Hossinarizona
Reply With Quote
Old May 27, 2012, 03:19 PM
Registered User
United States, TN, Jackson
Joined Mar 2007
4,011 Posts
Quote:
Originally Posted by Brickyard View Post
Not trying to start anything, but I'm very unclear as to why you guys want to go with a completely different design than today's successful sport jets? Bandit, Electra, futura, ultra flash/lightning/spark..etc, etc.. I don't get it
Of all of those planes mentioned none have the elevators larger at the tips than at the root...They, for the most part, look like Extremes example..

Kevin
Kevin Greene is offline Find More Posts by Kevin Greene
Reply With Quote
Old May 27, 2012, 03:26 PM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
21,866 Posts
im using cheap metal gear hextronic servos all over lol. i siliconed mine to the skin of the stab, and cut the mount tabs off the servo allowing me to also glue the servo to the balsa spar inside. mine is a little offset, but not enough to hurt.

major bummer guys.



Quote:
Originally Posted by jcdfrd View Post
good morning Brent
nick used hs 5085's throughout and the dimensions of that servo made it a snug fit in the elevator and too keep the control horn centered on the elevator he removed some of the mounting hardware block that the bolt goes thru to be able to slide the servo into the stab more and get a straight perpendicular shot to the elevator control horn. what this did was create a sandwich effect when the mounting the stab, 75% of the servo was covered by the stab skin and then the fuse skin when installed and when you tighten down the stab bolts it also clamped the servo in place. it was taped and glued (potted) to the bottom of the elevator skin as instructed in the manual but now after a 3hr ride home and discussing the failure and stopping occasionally to pull parts and inspect them, Nick is kicking himself a little for not epoxying all the way around the servo and the bottom against the wood block that would have helped but I think his install was good. the problem is when you have a bad design that creates weaknesses and then try to strengthen the weaknesses(better hinges and gap sealing) the failure point just moves down the line. in our case it was the servo mount. a normally good enough mount turned out not good enough for this design
corsair nut is online now Find More Posts by corsair nut
Reply With Quote
Old May 27, 2012, 03:28 PM
Robert Wagoner's Avatar
Tucson, Arizona, USA
Joined Dec 1999
1,552 Posts
Quote:
Originally Posted by Hossinarizona View Post
Mine
Yes.

--RW
Robert Wagoner is offline Find More Posts by Robert Wagoner
Site Sponsor
Reply With Quote
Old May 27, 2012, 03:36 PM
Robert Wagoner's Avatar
Tucson, Arizona, USA
Joined Dec 1999
1,552 Posts
Quote:
Originally Posted by Kevin Greene View Post
Of all of those planes mentioned none have the elevators larger at the tips than at the root...They, for the most part, look like Extremes example..

Kevin
Were going to gather some data on this and I'll share it.

--RW
Robert Wagoner is offline Find More Posts by Robert Wagoner
Site Sponsor
Reply With Quote
Old May 27, 2012, 03:42 PM
3DHOG
jcdfrd's Avatar
USA, CA, Aromas
Joined Sep 2010
4,847 Posts
Quote:
I have already stated that this Stab/Elevator design is not the most *optimal* design, but the hard fact is we're simply not generating enough force to cause aerodynamic flutter!
Vic
making a statement like this is not "avoiding drama" and is going to cause Flutter!!! in the mouths and keyboards all a crossed the world just watch...here comes the flutter lol!!

I do disagree with that statement so here's my flutter lol!!
design is a big part of the whole equation of flutter, design can create or prevent flutter, design can also increase or decrease aerodynamic forces being applied to controls and control surfaces. so here comes my updated opinion now with more data......I do agree with Vic that so far there has been no true flutter coming from the tail but disagree that we dont go fast enough to experience it, rather the poor design of the elevator shape is causing increased undue aerodynamic forces to the control system IE: hinge failure(Vics proto), elev control pushrod failure(alanjets) and elev servo control mount failure (Nicks)
this is how I see it with the SSXL data we have right now
I see two ways to fix the problem, change the design of the elevator(root cause) or make the control system strong enough to handle the increased forces. the one problem I see with the latter fix is that once the control system is strong enough to handle the additional forces this is actually when true control surface flutter may show its ugly head.

no disrespect Vic just trying to help us get to a proper resolution and hopefully a low cost easy one

John
jcdfrd is offline Find More Posts by jcdfrd
Reply With Quote
Old May 27, 2012, 03:44 PM
Registered User
United States, TN, Jackson
Joined Mar 2007
4,011 Posts
Quote:
Originally Posted by Robert Wagoner View Post
Were going to gather some data on this and I'll share it.

--RW
It's refreshing to have a distributor/manufacturer actually check to see if there is a real problem!!!...My hat's off to you!!!...You going the extra mile is something I'll think about the next time I need to scratch that new plane itch...

Kevin
Kevin Greene is offline Find More Posts by Kevin Greene
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Cool New HET L-39 90mm by EJF.com AceMigKiller Electric Ducted Fan Jet Talk 701 Aug 09, 2014 04:46 AM
Sold Crazy Price Drop!! HET Super Sniper with 70mm Mega/HET power system and servos. airmcn_3 Aircraft - Electric - Jets (FS/W) 9 Nov 14, 2011 11:37 AM
Found HET Sniper 90mm, airframe and maybe servos Knife Liddle Aircraft - Electric - Jets (FS/W) 2 Oct 01, 2011 11:10 AM
Sold NIB HET Super Sniper 90 V3 with HET 90mm fan and HET 600-37 motor mcgoughman Aircraft - Electric - Jets (FS/W) 0 Aug 30, 2011 08:35 PM
Sold HET All Composite Super Sniper priscalex Aircraft - Electric - Jets (FS/W) 0 Jun 30, 2008 09:17 PM