Originally Posted by webbsolution

If you dont do silly things to these planes you never have to change those horns.

David, I completely respect your X4 experience and skill in landing but from my own X4 experience, long ongoing reading of this thread, and talking to many other X4 owners in person, the (undersized) flap horns are a clear weakness of the X4 design.

I have heard the excuses for the current design including "that's the best place where you want it to fail" etc but I ain't buyin' it.

After 2 months of flying my X4 ST and going through 3 sets of horns early this year, I finally modified my landing "style" to not overstress this weak point. But it is a weak point that I have not had to worry about with other planes including my 79oz X3.8.

The X4 is an awesome plane and I wouldn't trade it for anything (except an Xv2) but the horn solution could be beefed up. Maybe with the lighter X2 layups this is less of a problem? Hope so.

Chris B.

I haven't broken anything from landing...
I broke one of my surface horns from over-tightening Didn't know my own strength, I guess.

Jun

Originally Posted by webbsolution

People - stop banging your flaps

If the horns are fully supported to the shoulder and still breaking, then I would consider removing them completely and install G10 horns, as on the Icon 2.

Tom

Originally Posted by SoaringDude

After 2 months of flying my X4 ST and going through 3 sets of horns early this year, I finally modified my landing "style" to not overstress this weak point. But it is a weak point that I have not had to worry about with other planes including my 79oz X3.8.

I miss the simplicity of the good old bottom mounted servo and linkage. Might have been ugly, but it was easy to set up, worked like a charm, and the incremental drag was never the reason I missed a time. And I bet that is true for 99.9999999999% of the soaring pilots out there.

Originally Posted by tewatson

If the horns are fully supported to the shoulder and still breaking...

Tom, I never had a problem with breaking, just slightly bending. I'd been warned to not just recenter if you slightly bend a horn so I always replaced them right away.

I also tried the epoxy+fibers fill thing and it helped but ended up cracking the wing surface in front of the horn during a gusty ballasted-up landing.

I fully acknowledge back in Jan/Feb I had way less experience with X building and flying and that was part of it. Truth be told the horns thing made me much more religious about snapping the flaps back just before nose touchdown. Been 5 months since my last horn bend. But I'm not a lawn dart kinda guy. This kind of thing just adds to the pilot load which I try hard to minimize...

Chris B.

I cant remember off tje top of my head but arent the horns made from brass? Could have sworn my 3.5 had brass. And if my memory is correct which it hardley ever is. But its a very soft metal and would break fairly easily with a hard jolt. Webbs right dont land with your flaps down. I would rather have this as a failure point than my servo or ripping my flap out. I land hard and as long as my flaps are up no issue.

Thanks for all the advise guys.......it helps an awful lot!! I have decided to go with shoulder seated stock brass horns for the ailerons/flaps with no glue and the stock rudder horn setup. Just to be safe I just ordered a package of each of the long and short horns from SUSA. They are a great bunch there!

Much appreciated

MJ

Originally Posted by tewatson

If the horns are fully supported to the shoulder and still breaking, then I would consider removing them completely and install G10 horns, as on the Icon 2.

Tom

I like G-10 horns, but if you are too chicken to use them, the Graupner 4mm aluminum horns are the bomb....
They are lighter and bigger and stronger than the brass horns; they don't have a neck downed spot to make a weak point....

R,
Target

Originally Posted by SoaringDude

David, I completely respect your X4 experience and skill in landing but from my own X4 experience, long ongoing reading of this thread, and talking to many other X4 owners in person, the (undersized) flap horns are a clear weakness of the X4 design.

I have heard the excuses for the current design including "that's the best place where you want it to fail" etc but I ain't buyin' it.

After 2 months of flying my X4 ST and going through 3 sets of horns early this year, I finally modified my landing "style" to not overstress this weak point. But it is a weak point that I have not had to worry about with other planes including my 79oz X3.8.

The X4 is an awesome plane and I wouldn't trade it for anything (except an Xv2) but the horn solution could be beefed up. Maybe with the lighter X2 layups this is less of a problem? Hope so.

Chris B.

Hey Chris - if its any consolation the leading edge is also not strong enough to withstand my shin as seen in the precup for the WC this August Man I was totally expecting my model to stick and at the speed it was coming in I had no time to move out of the way. We all make mistakes. Some punish us more than others.

I totally buy into the brass horns as the very best thing to break in the wing assemsbly when you are out side of the abuse curve- I dont want the servo horns snapping that takes longer to fix at the field esp with qa direct bonded servo - I dont want the flap hinge to tear or the wing skin and while I can make a set of pushrods in no time if I am abusing the plane I want a $2 item to be the replacement if possible.

This is like comparing how well the ATX SD-10G and the JR 11X hold up to hand launching into a nice field. One radio might survive better than the other but none of them were designed to hold up to that abuse curve.

Hey Webman.. so let me get this straight you guys are flying team Blue because
the Tx stands up better when you drop it??????
It was good hangin with you in SA LJ

Originally Posted by Larry Jolly

Hey Webman.. so let me get this straight you guys are flying team Blue because
the Tx stands up better when you drop it??????
It was good hangin with you in SA LJ

Actually in a true discuss contest the SD-10G would not be my bet ill give this one to team red. You cant win them all.

It was great to see you again LJ it always is. Ill see you at WSM in a few weeks?

Originally Posted by webbsolution

I totally buy into the brass horns as the very best thing to break...

And bend too. I appreciate your point. As I said earlier I changed my last second of landing "muscle memory" to always retract flaps 100% up before nose down.

Being an engineer by trade and at heart my design approach would have been to beef up the horn and the flap area around it.

Great posts on SA by the way. Thanks for sharing, sounds like a ton of fun.

After digging out 2 broken horns, each causing me to be done for the event, I concluded on my next build I might just drill a small hole thru the threaded insert and out the bottom skin right from the start. Grind a slot in the threaded tip of the brass horn and put it all together.

When the horn snaps off due to whatever, insert a small tip flatblade screwdriver into the access hole from below and turn out the broken part.

This way I won't miss a round hoping to get it back together in time.

I maidend my new X4 this weekend.
Easy build. I bought the servo trays ad harness with it which saved time. Had it ready to fly in a week of evenings between dinner and TV.
CG 112
One hand toss and on the winch. What a sweet ship. Easiest I have ever flown.
This is my first competition grade sailplane and what what a difference.
I think I will be moving it back a little.
Saturday and Sunday flying and only missed my time twice. Never had it this good before.
This is the 4th flying in the club and two more being assembled. Soon we could have a one design contest.
One member has the 3.5m 2X being put together. Now how am I going to swing one of those?

I flew my X4 at 112 (as per Bob's recommendation for a starting point). After a while I went back to 120. It is quite nice there. Best of luck with yours.