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Sig Kadet Senior Build

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Old 09-03-2011, 10:33 PM
  #1
kknack
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Default Sig Kadet Senior Build

Hi All,

Just curios how important the wing tips on a Kadet Senior are from an aerodynamic perspective. I feel I've built (first time) the entire wing structure very well, but when I got to the wing tips there was a bit of abiguity in the directions, my skills, and the available materials Specifically with the "scrap wood" for the "leading edge block". I think with some sanding and what not it's going to be a good looking, sleek structure, but not 100% certain both sides are going to come out exactly the same. I feel with a big wing trainer like this it's probably moot, just looking for someone to back me up on that The plans and directions kind of suck in this one area, the rest went pretty good.

Kyle
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Old 09-03-2011, 10:59 PM
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Default RE: Sig Kadet Senior Build

The wing tip caps that you esentially carve out of balsa are mostly decorative. They can provide some bumper protection on bad landings and hangar beatings so if you eliminate them concider adding a 1/8 balsa doubler cap strip flat on the ends.
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Old 09-03-2011, 11:57 PM
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Default RE: Sig Kadet Senior Build

G'day

Over the last 10 years I have built about 10 Kadet Seniors and the smaller Seniorita. All the wing tips have been slightly different and I eventually worked out my way of doing it. One, in particular had the two tips looking a bit different but it did not make the slightest difference to the way it flew. The Senior is a very tolerant design, will carry a lot of weight and will fly well with a great range of engines.

The wing tip is part of the Kadet's stability. It is there to help the wing tip not stall at low speeds. It is effectively "washout" which makes sure the tip will not stall before the inner part of the wing. But so long as it looks more or less right, it will work as intended.

At the present time I have one with a Saito 62 (perfect match), it used to have a Saito 56 (also great), another has a Laser 70 four stroke (great) and recently I have put an aileron wing on it (more versatile but less stable). I also have one with a Saito 90R3 three cylinder radial. It is being used to run the engine in in the air. And I have an ARF Kadet Senior which has had a Saito 65, ASP 91 four stroke (insane and eventually the wing would have failed), enya 53 four stroke (fine) and now has a Saito 72 (just nicely overpowered).

I also regularly fly two others which belong to people I have been teaching. One was built off the plan (no kit) and used to have an MDS 46 (terrible carby) and now has an old Saito 45, and the other has a Saito 62. Its owner is now flying solo. He was nearly 65 when he started to learn and has taken about 9 months to solo. The Kadet has made it possible for him.

Enjoy your Kadet. I enjoy mine.

Mike in Oz


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Old 09-04-2011, 05:39 AM
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Default RE: Sig Kadet Senior Build

As already noted the tip shape is not of major importance. But there is a difference though, the flat upswept bottom effectively increases the dihedral effect at low speed. So if you are using the higher dihedral no aileron wing the then you will never know the differance over a blunted or rounded tip.

If you have flatened the wing or had very low dihedral wing such as in the Nitro planes Super Senior then this small reduction in dihedral effect will be noticible not neccessarily bad but noticible.

John
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Old 09-05-2011, 07:24 PM
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kknack
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Default RE: Sig Kadet Senior Build

Thanks all!  It sounds like it'll work out ok.  Fundamentally it looks pretty much like the plans.

I have a new question, and if these needs to be moved to the kit building forums so be it.  I'm working on the second half of the wing, and the trailing edge piece appears to be bowed away from the ribs in the center section.  3-4 ribs in the middle, starting with the fourth rib from the center (counting the w1 that mated to the other rib), just -barely- make it into the notch.  Unfortunately I discovered this after gluing in the first three ribs.  I tried to wet and form the balsa, but I don't think thats going to work with the other ribs in place.  So I'm faced with two options:

1) debond the ribs I've already glued in and try and re-form the trailing edge piece

2) tack them in with some thin ca and cover with some wood glue for strength

Personally I'm not afraid of option 2, as I've done some pretty strong (non r/c) handywork with wood glue and am comfortable with its strength, but figured it'd be good to run by the experts here.

Here's a pic of the joint, although the photo makes the gap look bigger.  It's in there, but barely:


And here's the first wing for fun (still needs some sanding):

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Old 09-06-2011, 06:20 AM
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Default RE: Sig Kadet Senior Build

Hi, Your post is to difficult to read for us that cannot read screens with tiny resolutions. When your posted photos are not sized down or not sized down sufficiently then many of us will have to try to read each line of your text by scrolling side to side one line at a time.

This then tends to restrict the responses you will get. Some servers on occassion somehow giant size ones posted photos with the same effect. When this happens on one of my posts I delete the photos as it ruins the post and go back later to repost the photos when one of the other servers is in effect. I don,t think this is what happened with yours though I just beleve you have not sized them down enough.

What I think you posted about are warped leading and trailing edge sticks. They should be staightened as you noted by soaking with hot water before assembly and overbent the opposite direction to dry. Many times this will take several attempts.

If the airplane is assembled by pushing the stick in at the middle or the tips then what this will tranlate to if the bow is sufficient will be a torsional warp in the wing structure. Now with a wing like this with no leading edge sheeting top or bottom that forms a 'D' tube if there is a torsional warp fortunately its rather easy to eliminate with careful overtwisting and heating of the covering film (monocoat, ultracote etc).

John
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