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Old Sep 09, 2013, 12:44 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
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Dynaflite Decathlon

So, I have been taking the bits of wood in / out of the box for the past couple of months. Anytime something confusing comes up, it gets put away. This is only my second kit build and will be a float plane.

Going to post in the forum for help along the and suggestions. Appreciate your time to look through and comment.

For power, I have a RCG50
Floats from Ralph at planefunfloats

1st problem today.

Pg 10, step 11 of the manual on Building the Wing.

So, I have my spars, but the gaps in the ribs seem to be big. Are the spars supposed to seat in to the rib all the way? If I glue it down like this, the rear side of the rib will lift the spar off the plan and it will be in the air.

Also, are the rib numbers supposed to be the correct way round or upside down? If they are supposed to be in the correct orientation, my w3 doubler doesn't match the correct side of the plan.....

Going to post in the forum for help along the way and suggestions. Appreciate your time to look through and comment.

Thanks, Sandy
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Last edited by sandydr; Sep 09, 2013 at 01:55 PM.
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Old Sep 09, 2013, 09:47 PM
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Lnagel's Avatar
Moab, Utah, USA
Joined Apr 2003
6,285 Posts
The first paragraph in the wing building section of the manual says,
"Note: The airfoil used on this plane is semisymmetrical.
We positioned the embossed labels
on the die-cut 3/32" balsa ribs so that they are
right-side up when the wing is right-side up. This is
the easiest way to reference the top and bottom of
the ribs."
Step 10 of the wing building section says,
"10. Pin the 1/4" x 3/8" x 42" balsa wing jig to
the plans, with the 1/4" edge against the plans.
Notice how the jig is skewed to provide the
required wing twist (washout)."
That jig is shown on the plan with dashed lines. Unfortunately it is difficult to differentiate the jig from the dashed lines representing the starburst pattern, but it is there. The jig will hold the aft end of the ribs up so that slots in the ribs for the forward spar fit flush to the plan.

To the right side of the plan for the left wing there is a cross section of the W2 rib that shows how the hardwood spars should fit in the rib slots.

Here's a thread I started on the Dynaflite Super Decathlon. It's been on hold while I work on other projects. I can't believe it's two years old. I did some major modifications in my build, but some of it may help you.

Larry
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Old Sep 09, 2013, 11:39 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
Thank you Larry,
I didn't even thing to look at the side view, as it was drooping over the bench (out of sight...out of mind). That together with your photos have helped clear it up.
I think my problem started on step 1 pg.9 as I glued one of the doublers the wrong way round, hence it wasn't matching the plans unless it was inverted. Looking at the photos in the manual again, I can see where I have gone wrong.
Thanks again, Sandy
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Old Sep 11, 2013, 05:15 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
Think I have gone wrong again....

So, I am about to sheet the wing, but the spar doubler is really sticking out. Is this supposed to be flush with top of the rib?

Where the spar doubler tapers and go a single spar, all is good with the rib alignment.

Is it supposed to be like this? If not, should I just sand the doubler so it is flush, or alternatively, cut in to the rib more to allow the doubler to seat correctly.

As ever, any hints are warmly appreciated. Thanks, Sandy
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Old Sep 12, 2013, 01:54 AM
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Lnagel's Avatar
Moab, Utah, USA
Joined Apr 2003
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Again, refer to the W2 rib cross section and it shows you the relation between the top of the rib, the spar and the spar doubler. The spar should be level with the top of the ribs for the whole length of the wing. The slots in the W1, W2 and W3 ribs should be deep enough to accomodate the thickness of both the spar and the spar doubler.

Larry
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Old Sep 12, 2013, 02:34 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
Thanks Larry,

I went over it last night and decided to cut the W1-W3 ribs deeper to seat the spar. I did take a moment to check the cross section, but it only shows the side of the spar without the doubler. I also got confused on the terminology to do with the washout and thought perhaps that the doubler being higher, had something to do with that. Anyway, it's all sitting level now.

Regards, Sandy
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Old Sep 12, 2013, 05:51 PM
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Moab, Utah, USA
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Interesting. The W2 profile on my plan shows both the spar and the spar doubler.

Larry
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Old Sep 12, 2013, 09:44 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
Hello Larry,
I have the same plan and I have been referring to the aft spar. Pg9 no.7 where it refers to gluing the spar doublers and then 'These assemblies are now known as spars.'
I put one of these in on p.10 no.14, should I have just used a normal single spar? I have sheeted the top side of the wing now.....

Can't really go back without causing a lot of damage, so moving on, should I replicate what I did in this wing on the next, in the interest of balance?

Starting to think, this should have been a 3rd / 4th kit...Ooops!
Thanks, Sandy
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Old Sep 14, 2013, 04:15 PM
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United States, MD, Elkton
Joined Oct 2011
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Ahhh-you're doin' all right ! a couple of miss steps, but other wise okay...

If you have spar doublers on the rear spars you didn't do so good, but it's not the first time things like that have happened....Thing of it is, where are those doublers supposed to go ? You've probably shorted yourself somewhere else...

Never mind, if you have a Hobby shop close- get whatever you need....to replace the wood you used, but yes- do the same thing to the other wing..

Be sure you look at each step from several angles, and it'll become clearer with each step you take.

Earl
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Old Sep 14, 2013, 05:33 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
Thanks Earl,
Managed to get the spars embed and smoothed it all down now. Starting to look like a real wing Just flipped it over and sheeted the other side and put the servo rails in and a bit more sanding. Wondering whether the sanding of the end blocks is going to be therapeutic or insanely frustrating....
Regards, Sandy
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Old Sep 15, 2013, 04:24 PM
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Lnagel's Avatar
Moab, Utah, USA
Joined Apr 2003
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Your wing looks great. Most of the shaping those blocks of wood for the wingtips is best done with a sharp knife, or even a block plane. It goes a lot quicker and saves a lot of elbow grease over trying to do the whole job with sand paper.

Larry
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Old Sep 16, 2013, 04:49 PM
Need a bigger runway
sandydr's Avatar
Dominican Republic, Puerto Plata, Cabarete
Joined Mar 2008
248 Posts
Thanks Larry
Really do appreciate you taking the time to cast your eye over this.

So....like an idiot, I have been looking in the box for the leading edge which has a nice shape to it on the bottom of pg.13 (really need to learn to turn the pages more! ) and can now see that I need to shape it.

Is there a technique which I should follow? Try to do the whole thing at once or trace an outline at one end and try get that right and follow through?

Additionally, reading the part about the ailerons. The manual states to use a 3/8" x 7/8" x 24 balsa stick as the leading edge. I only have one of these left. Looking at the profile view, the widest point of the leading edge is 3/4". Test fitting the aileron ribs the 3/4" x 3/8" is also a better fit. Using the 7/8" would make it too big for the rib, requiring a lot of sanding of the stick to get it inline with the rib.

So, my question is...is this a mis-print? Should I use a 3/4"x3/8" leading edge?

Thanks, Sandy
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Old Sep 17, 2013, 01:25 AM
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Moab, Utah, USA
Joined Apr 2003
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Sandy,
I looked all over for my ailerons and couldn't find them. Then I realized that I haven't built them yet.

So I looked at the wing trailing edge in the aileron bay area. The wing trailing edge is indeed 7/8" high with 3/32" sheeting on top and on bottom. The aileron leading edge will have to match those dimensions, so I'm afraid the instructions and the plans are correct as to the 3/8"x7/8" dimensions. I looked in my unused stock and I do have two 3/8"x7/8"x24" pieces to use as the aileron leading edges when I get around to building them. I can only surmise that you may have used one of the 7/8" pieces where you should have used a 3/4" piece.

Larry
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Old Sep 17, 2013, 02:35 AM
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Moab, Utah, USA
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Shaping leading edges can be intimidating. I approach the task in stages. First I draw a line on the L.E. profile that is tangent to the curve. that line is represented by the red line on the attached diagrams. Then measure the distances from one corner of the square stock to where the line intersects the the two sides of the square stock profile. From those points on the actual balsa L.E. draw lines along the whole length of the leading edge. Then plane, carve, sand, or any combination of each, a flat between the two lines. Usually it only requires a flat on the top of the L.E. and flat on the bottom of the L.E. That takes off the majority of the waste material. Then it's only a matter of sanding down the remaining angular nubs to get a nice L.E. shape.

A small block plane or razor plane is just about a must here. It really saves a lot of time, sanding, and sawdust. The next best thing is to carve the flats with a sharp knife.

Here is a link to the way I did the leading edge on my Bristol Scout.
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Old Sep 17, 2013, 02:51 AM
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Moab, Utah, USA
Joined Apr 2003
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The aileron leading edge should be the same dimension as the wing trailing edge in the aileron bay as shown by the two red arrows in the in the attached photo.

Larry
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