The 'What did you do in your workshop tonight?' thread

[pawnshopmike]

Do you sell Savox servos looking for one Savox SB-2274 sg.

No sir. Sorry bro.

 

[pawnshopmike]

Now I got to build a plow to go behind it. Wear a green ball cap and spit tobacco!.....

View attachment 99729

That's what I like about you Kelly. You always find the silver lining!

 

[49dimes]

Do not know if this is the Correct place to ask but if not let me know. This is about CG. How does CG effect doing a knife edge. I do understand how CG effects lateral balance and how it can effect how your elevator. But when you change the CG how does it effect knife edge. Thanks for your help.

It can make the rudder more or less "sensitive" just like the elevator. In extreme cases of tail heavy it can make the plane unstable and stall easily just like the elevator. In KE rudder is the elevator and elevator the rudder.

 

[49dimes]

That's what I like about you Kelly. You always find the silver lining!

Guess I made lemon aide with a split of lime . Stuck with it because the other scheme was allegedly the last one available. No matter. No damage and construction seems excellent . Besides......IT WAS CHEAP because...........fill in the blanks here __ _________
John Deere Extra 330DNC.... "Dirt-Nap-Control" . And yes. My CF spinner will be getting a canary yellow paint job .

 

[Jetpainter]

Do not know if this is the Correct place to ask but if not let me know. This is about CG. How does CG effect doing a knife edge. I do understand how CG effects lateral balance and how it can effect how your elevator. But when you change the CG how does it effect knife edge. Thanks for your help.

If the plane is let's say nose heavy, you need just a tad of up elevator trim to fly level when upright. When you go knife edge that slight up trim will make it pull towards the canopy.

 

[Snoopy1]

Thanks that makes sense.

 

[49dimes]

Thanks that makes sense.

The engines "thrust line" also plays a role. The PAU Edge build I did for a buddy I had set 1.5 degrees right thrust and 0 up thrust. 2 degrees up thrust was built in . Should have left it that way. Applying power in KE or level flight made it pull towards the belly and slightly dive in straight and level. The cg was very close to neutral (more nose heavy though) and up elevator trim was needed for straight level flight at part throttle. We set it back to 2 degrees up thrust and it did much better and most the elevator trim was no longer needed.
IMO the way the "incidence" is set on the wing and stab have more to do with cause and effect in KE flight and straight level. I need to check the PAU Edge but I bet the wing incidence is O and the stab incidence is plus 2 degrees. This is done on a lot of 3D airframes so the wing tips stall together evenly.

 

[Snoopy1]

A lot of what you @49dimes and @Jetpainter have explained is making sense. I really appreciate the help. Making a plane fly level has a lot more effect on all the dynamics of the plane than what I was giving it credit. Getting it to fly level can screw up a few other things in the process. So what I am gathering from this is that flying level must be done with CG movement first with all the surfaces natural or kept as flat as possible. And when that is done as best as you can get it start to mix in elevator with rudder as the final fix for knife edge flying. Thanks.

 

[Jetpainter]

A lot of what you @49dimes and @Jetpainter have explained is making sense. I really appreciate the help. Making a plane fly level has a lot more effect on all the dynamics of the plane than what I was giving it credit. Getting it to fly level can screw up a few other things in the process. So what I am gathering from this is that flying level must be done with CG movement first with all the surfaces natural or kept as flat as possible. And when that is done as best as you can get it start to mix in elevator with rudder as the final fix for knife edge flying. Thanks.

Do a Google search for Peter Goldsmith trimming. He did a really good article on it.

 

[AKNick]

How worried should I be??

Had a heavy hub, put a piece of metal to balance it out vertically.


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