HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 08, 2013, 09:54 PM
Flightcomp.com
ak79's Avatar
United States, CA, Torrance
Joined Apr 2006
1,650 Posts
We all know the X is the best Bob, that's why we have nothing to do with our time than analyze every little detail.......kind of like trying to make pure sugar sweeter.
ak79 is offline Find More Posts by ak79
Site Sponsor
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 08, 2013, 10:23 PM
RIP MC
fnnwizard's Avatar
United States, CA, Midway City
Joined Dec 2003
3,215 Posts
Quote:
Originally Posted by ak79 View Post
We all know the X is the best Bob, that's why we have nothing to do with our time than analyze every little detail.......kind of like trying to make pure sugar sweeter.
Speaking of details, the bigger rudder looks to be poorly implemented due to it not being "constant percentage chord". Even on the X1 fuses, the upper part of the rudder is too much chord. At moderate deflections the upper half is generating more "lift" than the bottom portion and that actually makes it less efficient overall.
I point this out because it is obvious and if the rudder was cut an angle it would save a few grams and be just as efficient over the full throws .
fnnwizard is offline Find More Posts by fnnwizard
Reply With Quote
Old Mar 08, 2013, 11:40 PM
PaulG
Newcastle, NSW Australia
Joined Dec 2004
315 Posts
X1 4.0 X2 3.8 fuselages

Sorry my modem stopped talking to the server, or so I'm told. I was referring to an X1 4.0m fuselage in comparison to an X 2 3.8m fuselage. I though someone posted that the new X2 3.8 m fuse has the same moment arm as the X1 4.0 m fuselage.
pigly is offline Find More Posts by pigly
Reply With Quote
Old Mar 09, 2013, 12:54 AM
Win=span\massXpractice+lu ck
webbsolution's Avatar
Joined Jul 2007
2,963 Posts
Quote:
Originally Posted by pigly View Post
Sorry my modem stopped talking to the server, or so I'm told. I was referring to an X1 4.0m fuselage in comparison to an X 2 3.8m fuselage. I though someone posted that the new X2 3.8 m fuse has the same moment arm as the X1 4.0 m fuselage.
ah way less confused now - that actually makes way more sense.
webbsolution is offline Find More Posts by webbsolution
Reply With Quote
Old Mar 09, 2013, 06:57 AM
Registered User
Tuomo's Avatar
Jyvaskyla, Finland
Joined Aug 2003
2,421 Posts
Quote:
Originally Posted by pigly View Post
I though someone posted that the new X2 3.8 m fuse has the same moment arm as the X1 4.0 m fuselage.
That was me. See my post 456 in this thread. It has pictures...

http://www.rcgroups.com/forums/showp...&postcount=456
Tuomo is offline Find More Posts by Tuomo
Reply With Quote
Old Mar 09, 2013, 08:52 PM
Win=span\massXpractice+lu ck
webbsolution's Avatar
Joined Jul 2007
2,963 Posts
new Fubar x2 4.0

Took my brand - totally messed up X2 4.0 out for a re maiden - tips joined and repaired and the fuse wrapped and balanced at 127 now -

Did several hand launches back into my hands and then at the end of the day with the sun just starting to dip behind the hills I launched into slack wind - man for a no wind launch that 4.0 at 59 oz moves fast! and it still pinged off the line for a full 3 seconds.

Lift was super light in BC basically at the end of winter and 4:45 pm - but lot of stable area and a really easy read on the 4.0 I made 10 minutes with ease - im building out the full strength fuse as well - that one should be about 125 gr heavier than this build - so AUW of 1806 ish for the "heavy" version.
webbsolution is offline Find More Posts by webbsolution
Last edited by webbsolution; Mar 09, 2013 at 09:22 PM.
Reply With Quote
Old Mar 10, 2013, 04:04 AM
Registered User
Tuomo's Avatar
Jyvaskyla, Finland
Joined Aug 2003
2,421 Posts
David, how do you rate the strength of foam elevators? Safe wind limit?
Tuomo is offline Find More Posts by Tuomo
Reply With Quote
Old Mar 10, 2013, 08:42 AM
Win=span\massXpractice+lu ck
webbsolution's Avatar
Joined Jul 2007
2,963 Posts
Quote:
Originally Posted by Tuomo View Post
David, how do you rate the strength of foam elevators? Safe wind limit?
When Nan released the SL team planes with the foam tail group they suggested 3 meters per second as a wind limit which to me makes a lot of sense - I dont see a lot of point flying SL airframes above that wind level anyways - when the wind picks up I fly a molded stab -

OK so thats what Nan reported but pilots being pilots I watched Tristan Sherman and his Dad Launch there SL's in wind MUCH higher in South Africa and I too likely have flown mine well above 3 m -

I have had more challenges with the elevators de laminating due to what I feel are significant variances in atmospheric humility - when I came back from the world cup two of my foam tails had delams where they were perfect when I put them in the box protected by a corroplast shell with no indication of any impact at all. It took 2 minutes to fix it but now I keep those tails very well protected and I only use them when really required.
webbsolution is offline Find More Posts by webbsolution
Reply With Quote
Old Mar 10, 2013, 09:32 AM
Registered User
Tuomo's Avatar
Jyvaskyla, Finland
Joined Aug 2003
2,421 Posts
I was thinking of typical competition situation... How much can one strech the limits? I have also heard about the 3m/s limit, but it must be a very conservative estimation. 3m/s as an absolute max is almost nothing. When thermal passes a wind can rise from zero to above 3m/s almost instantly.

Elevator stress depends also on launch trim. I have seen Perfect elevator tips snap in hard launch - it was a very strong wind and this paticular plane had towhook in forward position with elevator trimmed up to keep line tension. With a more neutral launch trim elevator flutter is a more likely destruction scenario?
Tuomo is offline Find More Posts by Tuomo
Reply With Quote
Old Mar 10, 2013, 11:55 AM
Win=span\massXpractice+lu ck
webbsolution's Avatar
Joined Jul 2007
2,963 Posts
Quote:
Originally Posted by Tuomo View Post
I was thinking of typical competition situation... How much can one strech the limits? I have also heard about the 3m/s limit, but it must be a very conservative estimation. 3m/s as an absolute max is almost nothing. When thermal passes a wind can rise from zero to above 3m/s almost instantly.

Elevator stress depends also on launch trim. I have seen Perfect elevator tips snap in hard launch - it was a very strong wind and this paticular plane had towhook in forward position with elevator trimmed up to keep line tension. With a more neutral launch trim elevator flutter is a more likely destruction scenario?
I saw these stabs used in South Africa well into 6-8 meters on practice day - I dont know what the limit really is. The US team had a two fail but also some of them stated that they might have been banged up from rough field conditions like hay stalk and corn etc. Don't quote me there - maybe one of the US guys will comment.

To top it off they had 22 gr elevators so thats 30% lighter than any foam stab I have ever seen. They seems to be coming in around 32-35 now.

Maybe Paul Sherman will grace us with a post here I think saw him fly his SL X2 the whole time in South Africa with ballast - Aside from the very early morning round it was always above 6 most of the contest.

I can tell you that I dont spare these elevators on launch myself and have never snapped one. If I bring an SL to the line I am typically going to try and get that model to pull really hard but I do not use much more than 1-2 clicks of stab trim on launch. I do most of my tuning with camber and to hook - and the last 5% of perfection probably is never realized from my models yet but my launches are improving.
webbsolution is offline Find More Posts by webbsolution
Reply With Quote
Old Mar 10, 2013, 12:15 PM
F3B
satinet's Avatar
Warwickshire, England
Joined Sep 2006
5,505 Posts
horns

Hi

My "instructions" say to use the long horns on the flaps and the shorter horns on the ailerons. Looking at the ailerons this will give the horn a long way behind the hinge line, which won't be good geometry. The horn should really be in front of the hingeline for this type of install (top driven, bottom hinged).

Which horns are you using where? Or do you just junk them and put your own in?

Cheers
Tom
satinet is offline Find More Posts by satinet
Reply With Quote
Old Mar 10, 2013, 12:19 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
21,540 Posts
Not really, Tom...
For the ailerons, the hole behind the hinge line (slightly) is better than ahead. You typically want even or more up travel than down travel, which is quite the opposite of the flaps.
Also on the flaps, you need the horn ahead of the hinge line to keep the hole above the hinge line with full down flaps. You don't need that with the ailerons with less travel.
HTH.

R,
Target
target is offline Find More Posts by target
Reply With Quote
Old Mar 10, 2013, 01:09 PM
F3B
satinet's Avatar
Warwickshire, England
Joined Sep 2006
5,505 Posts
I generally go for exactly equal throws up and down on the ailerons and work from there. I haven't had many if any f3x models where I have not had enough aileron travel.

I have installed plenty of flaps Target, so don't worry I know all about the flap horn disappearing below the hinge line! been there....... I will bear it in mind though. At least the horns are adjustable which is better than if you glued in epoxy board horns wrong. Not that I ever have of course.
satinet is offline Find More Posts by satinet
Reply With Quote
Old Mar 10, 2013, 01:13 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
21,540 Posts
I know we all have (been there).
The point was that if you have to use the long horns for the flaps, that leaves you with what you have left for the ailerons.
I personally wouldn't mind if they had all 4 horns the longer in the kit for the wing.
That would save from using the tiniest of servo arms on the ailerons, which helps with not having to relieve the clevis too much....
Have fun.

R,
T
target is offline Find More Posts by target
Reply With Quote
Old Mar 10, 2013, 01:16 PM
F3B
satinet's Avatar
Warwickshire, England
Joined Sep 2006
5,505 Posts
Quote:
Originally Posted by target View Post
I know we all have (been there).
The point was that if you have to use the long horns for the flaps, that leaves you with what you have left for the ailerons.
I personally wouldn't mind if they had all 4 horns the longer in the kit for the wing.
That would save from using the tiniest of servo arms on the ailerons, which helps with not having to relieve the clevis too much....
Have fun.

R,
T
Yeah true. Smaller aileron horns mean less of the wing skin cut away for the pushrod I guess.

I might put some longer brass horns in as it doesn't seem quite how I want it. Will give it a try any way.
satinet is offline Find More Posts by satinet
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product 0.9g Retracts Mk.II *NOW LASER CUT* Yellow Baron Scratchbuilt Indoor and Micro Models 2 May 29, 2012 04:38 AM
Wanted Hangar 9 Spitfire MK II 60 Parts cessnajfb Aircraft - Fuel - Airplanes (FS/W) 2 Mar 11, 2012 08:47 PM
Sold *Price Reduced* Saito FA-45 MK II sscherin Aircraft - Fuel - Engines and Accessories (FS/W) 1 Mar 11, 2012 12:06 PM
For Sale: Carl Goldberg Classic Falcon 56 mk II and Skylark 56 mk II kasra Aircraft - Fuel - Airplanes (FS/W) 2 Nov 22, 2004 03:35 AM