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Sig Mid-Star 40 build question* - 12/26/2012 5:41 PM   
lamarkeiko


 

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From: Grants Pass, OR, USA
Status: offline 		 I'm just starting a winter build of a Mid-Star 40.  I'm not planning on bashing the original plans much.  Was considering adding some to the rudder and elevator, if there was opinion recommended to do so.  The one thing I want to do for sure which deviates from the original plans, is use 2 aileron servos instead of 1 servo with torque rods as per plan.  My question is how many rib bays from center should I put the servos, and can I mount the servos in the same plane as the servo pictured in the attached photo?  The wing is sheeted only 2 bays out from center, so I thought the 2nd bay would be a good spot to put the servos.  The 2nd bay is also where the torque rods are shown on the plan to attach to the ailerons.  A couple planes I've built previously seem to have the aileron servos somewhat further out from center and control horns attached out more from the end of the aileron.  My concern is that the control horn shouldn't be attached to the aileron so close to the end.  Any advice is appreciated, and also some ideas on how to build a servo mount in the wing bay.  I haven't found a complete build thread for the Mid-Star 40 to get ideas from.

Lamar

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RE: Sig Mid-Star 40 build question* - 12/26/2012 6:08 PM   
eddieC



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Status: offline 		Distance out on the wing is partly dependant on how stiff the aileron is. If the aileron stock is too soft, it can lead to control issues due to flex and possibly flutter. Most aileron stock is fairly rigid thankfully, so your mounting position sounds good. I like to mount the servo as near to the aileron center as possible, just my preference.

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RE: Sig Mid-Star 40 build question* - 12/26/2012 11:41 PM   
foodstick



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Status: offline 		Build a frame into the bay you choose, and then mount the servo to the lid that fits down flush into that frame. You will really like this plane, it flies better than the four star, but seldom gets mentioned.

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RE: Sig Mid-Star 40 build question* - 12/28/2012 6:06 AM   
KitBuilder



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Status: offline 		THe mid star flies better than the 4 star? I did not know that. I had the 4 star and loved it though it's no more ... I like the old schol planes and have a nice running 46 available . What about the Cavalier?

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RE: Sig Mid-Star 40 build question* - 12/28/2012 4:52 PM   
lamarkeiko


 

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Status: offline 		I've decided to place the aileron servos in the third bay from center. That will keep the control horn further from the end of the ailerons.  Also from this bay, I won't need any servo extensions.  By placing a short paper tube between a couple ribs, I can easly fish the servo leads through. 
   I would like to here from anyone with experience with the Mid-Star, if any extension to the rudder or elevator would be recommended.  I have an OS 46 ax that I will be flying the Mid-Star with.  Are there any issues with balancing this plane that I might address while building, so I don't have to add any weight.
      Thanks for any help
             Lamar

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RE: Sig Mid-Star 40 build question* - 12/28/2012 5:18 PM   
lamarkeiko


 

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Status: offline 		One thing I forgot to mention, and would appreciate some input on.  While gluing the center W-1 rib, and using the Dual Tool dihedral gauge, I was noticing that the gauge looked very square.  I checked the gauge with my square, and it does seem perfectly square.  The manual says there is only 1 deg. dehidral in each wing.  Should I have any concern now, or just make sure the 1" wing tip height is there when I glue the wings together?

Lamar

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RE: Sig Mid-Star 40 build question* - 12/28/2012 5:46 PM   
Top_Gunn


 

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Status: offline 		My Midstar 40, which flies very well, has no dihedral, an enlarged (maybe 30%) rudder, clipped wings, and slightly widened ailerons. How it flies depends on the cg. First flights it was somewhat nose heavy. It was a go-where-you-point-it plane, very easy to fly, but it wouldn't snap roll or even spin. I moved the CG back some and it's much livelier. A couple of times I've mistakenly taken off with high rates selected, and it gets exciting that way.

A .46 is overkill. I use a Thunder Tiger .35, which is great. I did need some nose weight with the .35.

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RE: Sig Mid-Star 40 build question* - 12/28/2012 9:40 PM   
foodstick



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Status: offline 		One thing I often heard was that the Midstar settles much MUCH better on landings as well. The Four Star really gets into ground effect for a long time. And can be prone to bouncy landings, and the infamous break right behind the wing saddle.

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RE: Sig Mid-Star 40 build question* - 1/7/2013 3:54 AM   
lamarkeiko


 

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Status: offline 		I've completed building one wing, and I'm ready to start the other.  One thing that I'm a little concerned with is that the wing seems to flex very easly when given a slight twist.  I was considering putting some diagonal bracing between the ribs to stiffen the wing up some.  Does this sound like a reasonable idea, or should I not be concerned with the flexable wing?
   Lamar 

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RE: Sig Mid-Star 40 build question* - 1/7/2013 4:45 AM   
foodstick



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Status: offline 		The covering will really strengthen it. The wing itself is not really designed for violent maneuvers though. So any strength you add without building to heavy would be fine...

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RE: Sig Mid-Star 40 build question* - 1/7/2013 2:03 PM   
Top_Gunn


 

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Status: offline 		I don't think you really need the diagonal bracing because, as Foodstick says, the covering adds a lot. But if you want to add it, 1/16 balsa is plenty strong enough for that use and adds hardly any weight.

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RE: Sig Mid-Star 40 build question* - 1/7/2013 4:19 PM   
lamarkeiko


 

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Status: offline 		Thanks Al & foodstick for your input.  I may add the bracing, but I think I'll hold off for awhile to see how the weight is coming.  I plan on using Solartex & painting, which may add some extra weight, but I believe the fabric will be much stronger than a plastic film.  I'm also building as a tail dragger, which should help keep the weight down.  
Al, did you fly your Mid-Star as a tail dragger?  You mentioned that your plane was a little nose heavy at first and you were flying with a .35, but then you said you had to add a little nose weight.  You have me a little confused.
 
    Lamar 

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RE: Sig Mid-Star 40 build question* - 1/7/2013 4:46 PM   
Top_Gunn


 

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Status: offline 		Lamar,

Yeah, mine's a taildragger. When I built it I put some lead weights (maybe 3 or 4 ounces; don't remember) up front to get the CG where I thought it ought to be. Flew Ok (very well, in fact) but not lively enough, so I took out some, but not all, of the lead and moved the CG back. Now it snaps and spins with the best of them, though it's not the relaxing flyer it was before. My impression is that SIG's recommended CG positions are pretty conservative. Good starting points, but a lot of people will want to gradually move the CG back some as they get used to the plane. Really depends on how you want to fly it.

As my plane had seriously clipped wings and an enlarged rudder, my CG experiences may not be a good guide to how yours will work out. For everyday flying, I don't think my changes affected the performance much, though. A guy in my club built one exactly as designed. I did the maiden flight for him and it wasn't a lot different from the way mine flew except for roll rate.

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RE: Sig Mid-Star 40 build question* - 1/7/2013 5:10 PM   
83scamp


 

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From: Columbia City, IN, USA
Status: offline 		I've got a Mid-Star that I have been flying for close to 15 years.  I built it to plans, and it is a wonderful flyer.  It built lite, and flies beautifully.  Mine is a trike, because I built it for use in club funfly's.  I originally powered mine with a Webra Speed 40 until it recently died.  Now it had a K&B .48 on it.  It took a lot of lead in the tail to balance with the K&B!  It really is overkill.  I think I'm going to pull that off, and go back to one of my old reliable Royal .40's.  I'm sure the OS 46 will be more than enough engine.

Don't expect wild aerobatics with the Mid-star.  It's just a nice gentle easy to fly plane.

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RE: Sig Mid-Star 40 build question* - 1/8/2013 11:43 AM   
Bill Diedrich



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Status: offline 		Here is what my servo placement was like in my Mid-Star.
Also sheeted the turtle deck aft of the cockpit with 3/32 basla
for stiffness.

BD

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