Author Topic: "Imitation" wing jig (Read 4171 times)

Warren Wagner · « **on:** July 28, 2006, 09:13:17 AM »

Wing jigs seem to be a common topic of discussion, so I thought I would add a little fuel to the fire, and perhaps give you some food for thought. This information may be helpful to less experienced builders that don't have their own pet way of building wings.

The plane under construction is an Ultra Hobby kit of the Ted Fancher designed "Imitation" published way back in 1979 in the Sep and Oct issues of Model Aviation. That article is required reading even if you don't plan on building the plane.

This software doesn't allow one to caption each specific photo, so I will describe the two photos, and point out items of interest.

First of all, if you look closely, you can see that the laser cut ribs had leveling feet on each rib so the wing can be built directly on a flat surface. The only problem with this is that there is no provision to jig up the wing when it is turned over for construction of the second side. I'm a firm believer in securing the wing in a stable jig until the wing is completely built. With that requirement in mind, I fabricated the jig blocks that would secure the wing by the leading and trailing edges, both right side up and upside down

.

The jig blocks were cut out on a 10" table saw, and if you notice, the jig for the TE is two pieces that run full span. This was just an experiment, and in hind sight, I prefer multiple jig stations, because they can be fabricated with greater accuracy.

The jig blocks are lightly CAed to the plate glass which was leveled with thread, and shimmed as needed. The plans for the wing are under the glass, and used only for reference. The actual location of all parts are marked on the LE and TE pieces. Vertical alignment of the ribs is insured by the use of the 6" combinations squares. CA is used for gluing at this stage of construction. You will note that the bottom TE sheeting and the TE (previously joined) is already in the TE jig block.

The plate glass is 4' long, so the wing overhangs the ends by about 1 1/2 rib bays, which is not a problem.

At this point, the LE sheeting is added along with the cap strips, then the wing is unpinned from the jig and inverted for installation of the landing gear blocks, bellcrank, lower LE sheeting and cap strips and center section sheeting.

Hope this information is helpful to some. If you have questions, fire away..I'll try to answer them.

Cheers.

Warren Wagner

Ironbomb · « **Reply #1 on:** August 28, 2006, 07:16:43 AM »

Warren, I like what I see there. While I am using a wing jig for the first time, I see advatanges to your method.

How is the wing secured to the blocks? does sit firmly within the blocks you cut? or do you have a clamp screw or other way of holding the wing in place?

Thanks for the pics

Greg

Dick Fowler · « **Reply #2 on:** August 28, 2006, 09:00:34 AM »

Another method for building wings is Tom Morris' Lincoln Log Method (LLM). It looks very much like what you are doing. I've built wings using Adjust-O-Jigs and still end up with some unwanted dihederal or a twist in the TE. I build straight wings with the LLM. It works well for me.

Leester · « **Reply #3 on:** August 28, 2006, 11:45:34 AM »

Greg: Pin it to the jig blocks.

Bill Little · « **Reply #4 on:** August 28, 2006, 04:39:00 PM »

Hi Warren,

That looks great. What powertrain are you planning to use on the Imitation?

I'm lazy and building mine from some foam cores thjat have been around for almost 20 years.

Haven't decided what engine to use for sure. Thinking about an OS 40VF and pipe. No lack of power there.

Bill <><

Randy Powell · « **Reply #5 on:** August 28, 2006, 04:44:48 PM »

Bill,

Nothing like overpower. I like it. Wish I could find another OS40VF NIB, but they are gettin tough to find.

Bill Little · « **Reply #6 on:** August 28, 2006, 04:47:28 PM »

Quote from: Randy on August 28, 2006, 04:44:48 PM

Bill,

Nothing like overpower. I like it. Wish I could find another OS40VF NIB, but they are gettin tough to find.

I have two great OS 40VFs left. I really do not believe that you can wear one out flying stunt! (ask Paul!)

Bill <><

Warren Wagner · « **Reply #7 on:** September 03, 2006, 12:51:44 PM »

Quote from: Ironbomb on August 28, 2006, 07:16:43 AM

Warren, I like what I see there. While I am using a wing jig for the first time, I see advatanges to your method.

How is the wing secured to the blocks? does sit firmly within the blocks you cut? or do you have a clamp screw or other way of holding the wing in place?

Thanks for the pics

Greg

Greg,

Sorry for the delay in responding, but would you believe, we were invited to spend a week at a villa in the Tuscany area of Italy, and we just got back. What a great invitation, and what a beautiful country !

Leester is correct, the wing is just pinned to the jig. You can see some of the colored, round pin heads in the right hand panel. The TE pins were removed in preparation for adding the upper TE sheeting. The pins go right back in after the sheeting.

The trailing edge pine jig was hard enough that I had to use steel pins and a small tack hammer. During the course of building, occasionally one adjusts one or more of the front jig blocks to make them snug. If you have used the right amount of thin CA, the blocks will pop off with a light tap from a hammer. This allows one to readjust the jig station and keep it tight. After this is done a few times, the wing is captured so securely in the jig, that the pins are just insurance.

In the attached photo, you can see the TE pins clearly. Also, you can see the *forming* of the LE sheeting. Though it is not obvious from the photos, this is a THICK wing ( at 2 1/4") so preforming of the LE sheeting is necessary. Not having any foam wing blanks to use, I finally ended up forming the sheeting directly on the wing.

Here's a point to bear in mind. Because the balsa is wet at the time it's pined to the wing, when you are finished, you will have a lot of ugly *dents* where the pins held the leading edge of the sheet. To avoid this, I used some solid scrap balsa and pined the leading edge sheeting down in place with that. On the rear of the sheeting, I used the 'special' clothes pins (pin halves reversed on the spring, and small pieces of balsa glued to the tips for dent-free clamping), as you can see. The results are a preformed leading edge sheeting ready to glue in place with no stress built into the structure.

Cheers,

Warren Wagner

Ironbomb · « **Reply #8 on:** September 03, 2006, 01:23:47 PM »

Italy!! cool, glad you had a good time, and returned safe.

Thanks for the pic and info. I dont know if I am up to that kind of construction yet. I think I understand a little more each time I build a plane. When the steel rod jig holds no more mystery, I may hit you up for more info about your wing jig there.

A question, is the leading edge sheeting glued down while it is wet, or wait till it is dry and shaped?

The Imitation is a good looking airplane, cant wait to see yours when its done.

Greg

Warren Wagner · « **Reply #9 on:** September 03, 2006, 02:08:42 PM »

Quote from: Bill Little on August 28, 2006, 04:39:00 PM

Hi Warren,

That looks great. What powertrain are you planning to use on the Imitation?

Bill <><

Bill,

The flexibility of choosing engines, by use of the RC motor mount, was one of the reason I choose to build the "Imitation". After never having owned the 'holy grail' of stunt engines, I now have obtained three ST46s, so I've now got the pleasure of learning all about the ST46. So, initially, a ST46 will be on the nose, as it shows on the plans.

However, I am very fond of my OS Surpass 40, and it will just have to wait its' turn to power the "Imitation".

Before going into a good plane, I like to get air time and experience on any new engine, so the "Imitation" will fit the bill for that need perfectly.

Cheers.

Warren Wagner

Warren Wagner · « **Reply #10 on:** September 03, 2006, 02:49:11 PM »

Quote from: Ironbomb on September 03, 2006, 01:23:47 PM

Italy!! cool, glad you had a good time, and returned safe.

Thanks for the pic and info. I don't know if I am up to that kind of construction yet. I think I understand a little more each time I build a plane. When the steel rod jig holds no more mystery, I may hit you up for more info about your wing jig there.

A question, is the leading edge sheeting glued down while it is wet, or wait till it is dry and shaped?

The Imitation is a good looking airplane, cant wait to see yours when its done.

Greg

Greg,

You say that you don't think you are up to this kind of construction. There is nothing difficult about it, at all. It's the common situation with anything new:

The first time you do it, it's confusing.
The second time you do it, it makes sense.
The third time you do it, you're an expert.

Anytime you have questions, please feel free to ask.

You asked:

"A question, is the leading edge sheeting glued down while it is wet, or wait till it is dry and shaped? "

I did the forming and the gluing in two separate steps. I never considered gluing the LE while it was wet, but it would be worth a try.

You commented:

"The Imitation is a good looking airplane, cant wait to see yours when its done. "

The only "teaser" that I will give you, is that I have selected purple ULtracote for the wings, and plan on painting the fuse and tail white. Think I will follow the Fancher original scheme just for fun.

Cheers.

Warren Wagner

Greg L Bahrman · « **Reply #11 on:** September 03, 2006, 03:50:45 PM »

Warren,
Question. You say you built the wing top side up and then flipped it over. Why couldn't you call it the bottom side and install the gear blocks etc. Do some sheeting and then turn it over and do the bellcrank etc. Does it make a difference?? Thanks

Bill Little · « **Reply #12 on:** September 03, 2006, 07:19:08 PM »

Quote from: Warren Wagner on September 03, 2006, 02:08:42 PM

Bill,

The flexibility of choosing engines, by use of the RC motor mount, was one of the reason I choose to build the "Imitation". After never having owned the 'holy grail' of stunt engines, I now have obtained three ST46s, so I've now got the pleasure of learning all about the ST46. So, initially, a ST46 will be on the nose, as it shows on the plans.

However, I am very fond of my OS Surpass 40, and it will just have to wait its' turn to power the "Imitation".

Before going into a good plane, I like to get air time and experience on any new engine, so the "Imitation" will fit the bill for that need perfectly.

Cheers.

Warren Wagner

Hi Warren,

I have a real soft spot for Super Tigre 46 stunt engines!

I'm with you on the "flexibility of the engine mounting system. I intend todo some "comparison testing" with several different engines when I do get mine done. I have a few I do believe will be good for the Imitation.

William Davis here in NC has been flying a hand me down Imitation (foam wing, and OLD! HAHA) with a Stan Powell reworked old K&B 40. It's the same type Les McDonald used on one of his WC Stillettos. Flys it just fine. I have seen os 46LA used, ST G51, and an older OS 46 (FSR??). All did the job quite well.

I do want to try Ted's suggestion of using an OS 40VF on pipe. I have grown addicted to having more power than is needed!

Good luck with yours and give us updates!
Bill <><

Ironbomb · « **Reply #13 on:** September 04, 2006, 12:17:23 PM »

Ok Warren, I'll be building the wing for my Dreadnaught 40 pretty soon, I'll bug you when I am ready. I have a couple other projects to finish up, mostly crashed planes that are ready for covering, then the Dread. Thanks for the encouragment.

Greg

Ironbomb · « **Reply #14 on:** September 04, 2006, 12:25:42 PM »

duplicate entry, deleted...

Greg

Bill Little · « **Reply #15 on:** September 04, 2006, 01:28:37 PM »

Hi Greg,

As long as youkeep the asymmetry correct (it might be confusing if you build it upside down) then which side you "start" on doesn't matter. It just seems convenient to start with the wing over the plan which means you begin building the "top" first.

I lost my second and third "built up" stunt planes back in '63 because they were my fist "inverted engine set ups, and when I turned the fuselage over to drill the mounting holes for the engine, I gave it "inset". Took me two planes to figure it out!

Bill <><

Warren Wagner · « **Reply #16 on:** September 04, 2006, 06:18:26 PM »

Quote from: Greg L Bahrman on September 03, 2006, 03:50:45 PM

Warren,
Question. You say you built the wing top side up and then flipped it over. Why couldn't you call it the bottom side and install the gear blocks etc. Do some sheeting and then turn it over and do the bellcrank etc. Does it make a difference?? Thanks

Yes, it does make a difference, because the wing is NOT symmetrical. The right wing is 3/4" shorter than the left wing, and the plans show the view of the TOP of the wing. You could do it, but it would be confusing and there is no advantage in doing so.

Which brings up a good point....because of the asymmetry of the wing, when it is turned over for the bottom contruction, the jig layout is not going to be the same as the top view. As it turns out, it's not a problem at all...the wing just gets shifted to one side until it fits securely in the jig. You may want to adjust one or more of the LE jig blocks for a snug fit.

Here is a shot of the bottom side of the "Imitation" wing. The landing gear blocks are all in, and the center section is sheeted. With the wing securely held in the jig, one has both hands available to manipulate a large sanding tee-bar for the very easist and best leveling of the wing panels.

Cheers.

Warren Wagner

Bill Little · « **Reply #17 on:** September 04, 2006, 08:36:30 PM »

Hi Warren,

I was so glad when Great Planes brought those sanding bars to market! A rather inexpensive, truely straight, "block" that is long enough to do an entire panel! I have all the available lengths and apply new paper with double sided golf grip tape, 2" wide. Best tools I have sometimes! Everyone should have them.

Bill <><

Ward Van Duzer · « **Reply #18 on:** September 08, 2006, 03:00:44 PM »

A word of caution when thinking about wetting LE sheeting to apply. I did this on my "scale" '52 Nobler for the '92 Nats. Somehow through expansion/contraction of the wet wood (I only wiped down the outside to make it curve) I developed the most beautiful curved dihedral you ever saw! (On the LE only!) Not many saw it, but it was there! Yup, the trim tab helped...

proparc · « **Reply #19 on:** September 16, 2006, 01:45:49 PM »

Warren,you are doing beautiful work man. Arfs may be popular,but they will never out-do this type of craftmanship.

Bill Little · « **Reply #20 on:** September 16, 2006, 04:43:05 PM »

Quote from: Ward Van Duzer on September 08, 2006, 03:00:44 PM

A word of caution when thinking about wetting LE sheeting to apply. I did this on my "scale" '52 Nobler for the '92 Nats. Somehow through expansion/contraction of the wet wood (I only wiped down the outside to make it curve) I developed the most beautiful curved dihedral you ever saw! (On the LE only!) Not many saw it, but it was there! Yup, the trim tab helped...

Hi Ward,

Did you wet AND glue at the same time, or let the sheeting dry, then glue it? Seems that after it has dried (been molded), then glued, it would do what you referred to.

Bill <><