Katana Revisit

abaser

Well-known member
I'm in the process of setting pivots for control rods and servo horns. In testing the pivots, I've come across something that I can't figure out. On the wings, I have 3 rods and horns. I can select every horn and rotate all at once using the local setting, and things go as planned. However, if I select all of the rods, after the second is selected, the pivots move to the center of the rod. Doing them individually is fine, but what makes them different from the servo arms?
 

abaser

Well-known member
With a fresh mind this morning, I opened max and saw the same results as last night. Once again,i started checking individual pivots and realized 2 of the rods had not been named yet. Since my rods are all duplicates of the original, they shared the same name with copy## at the end.

So, I named them correctly selected them all again, and things worked as planned. Not sure what naming had to do with it, but it worked all the same. :D
 

abaser

Well-known member
Two questions. I'm trying to set up a moveable pod on my canopy so that it hinges in the rear, and the front opens. However, the physics is working just the opposite. It's pivoting from the front, and rotating down instead. Can that be fixed? If not, I'm not going to worry about it much as I feel it will only be used on the ground anyway, but thought I'd ask anyway.

Second, when I imported, I had a visible motor. Upon deleting all of the base wire frames, my motor no longer shows, and the prop is placed inside of the fuselage. I've never run into that before. It still shows as an option of a base component, but no visuals. Does being a modeled engine have something to do with this?
 

jeffpn

Well-known member
There is an offset in the pivot in the RF editor. Try that.

Don't name your modeled engine ~CS_ENGINE. Name it anything else. In mine, I just combined the engine with the fuselage, since I wasn't wanting it to break off.
 

abaser

Well-known member
The visual canopy rotates fine, just like I want it to. The wire frame however pivots from the front instead of the rear and goes down.

The engine is named ~CS_BRISON. I'll probably just combine it as Jeff suggests, but wondered why that would happen.
 

abaser

Well-known member
I stumbled across something I'm curious about. When setting up my elevators, I went to add a pod for the counter balance tips. In doing so, I mistakenly added symmetrical moveable pods to thew h stab. This created the perfect shape for the elevator. I deleted the control surfaces I added, and changed the fuselage drag to 100% and this gave them control. Is this the wrong way, or will it work correctly?
 
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Boof69

Well-known member
I usually add the symmetrical pod then position it on the hinge line then I add a symmetrical wing to the pod. This is in my opinion the correct way. A movable pod is calculated like a fuselage. With top and bottom airfoil too.
 

abaser

Well-known member
My reason for asking is I usually see a separate tip pod on your setups. Doing this method created the actual shape of the elevator. No need for the tip pod, and one less thing for me to forget when changing throws.
 

Boof69

Well-known member
Then you should use it. I was just saying that the aerodynamic calcs are technically in correct because of the top and bottom airfoil.
 

abaser

Well-known member
That's what I wasn't sure of. Whether it was correct to do it that way or not. I haven't seen it used before, and got curious as to why.
 

Boof69

Well-known member
You could add all your parts via movable pod or detachable pod and get the perfect shaped wireframe but aerodynamically the model would be considered a bunch of tubes bolted together.
 

willsonman

Well-known member
Yes and no. MOST of the time the top-bottom will only effect side-side aerodynamic calculations. The work around here could be done with COP modification to reproduce the overall effect. I have found that over all shape of a control surface is not nearly as important as area. If your area is roughly what it needs to be you are on the right track. It really is next to impossible in the sim to reproduce say, for example, the elevators of my FFVS J-22. The tail has curved trailing edges. Never gonna happen unless pods are used. Well... not true. To avoid a complicated setup I reproduced an equivalent setup using approximate area as I mentioned. Sim flew just like my scratch built model.

I have to say that most folks need to keep in mind how forgiving our models can be aerodynamically because air does not scale.

Now, you COULD use a hybrid effect here. only the tips of the elevators need the MPs so do that. Make a wing out to the end of the H-stab. Add an extension to get the TE of the elevator tip and add a MP to get the LE of the elevator tip. Not sure its worth the effort but it may. The fun part is trying and seeing how it pans out. Find a few videos of a similar plane flying and try to reproduce the same move and see how the plane reacts. That is how you tell how effective it may or may not be.
 
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