Rudder horn idea again

[Dave Stroud]

I asked this question before but got no replies so before I go ahead, I'd like to ask the question just one more time. The elevator horn applies pressure directly onto the elevator spars through that common steel tube. The rudder horn is designed to apply pressure directly to a single rudder rib, which transmits the pressure through it's leading edge gussets into the rudder spar which then transmits the pressure back through the rest of the gussets and into the rest of the rudder ribs. Why not make the rudder horn behave like the elevator horn....directly into the spar ? Just wondering here...what am I missing ? Thanks.

[Dan_.]

I asked this question before but got no replies so before I go ahead, I'd like to ask the question just one more time. The elevator horn applies pressure directly onto the elevator spars through that common steel tube. The rudder horn is designed to apply pressure directly to a single rudder rib, which transmits the pressure through it's leading edge gussets into the rudder spar which then transmits the pressure back through the rest of the gussets and into the rest of the rudder ribs. Why not make the rudder horn behave like the elevator horn....directly into the spar ? Just wondering here...what am I missing ? Thanks.

Just an opinion but I don't think the rudder horn is behaving as you describe.  I would think the idea in both cases is to spread the air loads as evenly as possible across the assembly in the lightest way possible.

Also, pitch control is paramount, so you would likely spend a little more of your weight budget on it.

Nothing says you cannot weld up a rudder horn with a sleeve to slip over the spar and bolt it on there similar to the elevator setup.  It is most likely going to be heavier than it needs to be however.

Just an opinion for the sake of discussion...

[Dave Stroud]

I do think that the rudder rib that the rudder horn is attached to does take the force applied by your feet on the rudder pedals. I was wrong in saying that all the effort or pressure goes directly to the rudder spar because some of that pressure would also go back through the rib to the trailing edge tube. 

What I forgot to mention in my first post above was that my idea to make a rudder horn similar to the elevator horn would allow the rudder horn to be part of the lowest rudder hinge and cut down a bit on the weight you correctly mention above. In a nutshell, the rudder's lowest hinge part could have a rudder horn welded to it.

[Dan_]

10-4...  

Is there not a riveted connection from that gusset to the rudder spar..?  That would make the spar share the load.  (I already put my plans back up.)


Whatever I decided to do on it, I would make sure to keep as much of the assembly as possible connected together to spread the loads.

Looks like Les did his real close to the plans...

[Darren C]

I think I have done what is being described regarding a similar setup for the rudder and elevator horns.
Made mine from 4130N and found it was lighter than the plans aluminum.

http://www.mykitlog.com/users/display_log.php?user=ontherun&project=2554&category=11775&log=231472&row=8

Darren 

PS
My build has been delayed a few days whilst I replace all the tools stolen during a break in at the factory. 
Thankfully the LE was not touched.

[Dave Stroud]

Crikey, Darren... ! That's exactly what I had in mind. Nice one. Now we'd have to throw in the weight of some attach fittings but overall it would likely add no weight and might be a better setup.