Scratch Building: Transfer A Drawing To Wood

1928 Fairchild FC-2W2
1928 Fairchild FC-2W2

We’re converting a Hobby Lobby Telemaster into a 1928 Fairchild FC-2W2 for a National Parks Service program. This aircraft was the first ever owned by NASA and later the first owned by the National Parks Service. Information link at bottom.

While making a complex former, I felt the method was simple, interesting and important to share. Having arrived at the shape, I used the following method to copy it onto the material I wished to cut it from. The simple technique could help you build any aircraft from your own or purchased drawings.

Drawing of Fairchild FC - 2W2 Former
Drawing of Fairchild Former

1. First we need a drawing. If your making “one off” parts as I am in this example, simply draw the part on standard 20 lb copier paper using pencil. I make lots of changes and mistakes as I go, so it’s important to have an eraser equipped pencil.

Headless Telemaster/Fairchild

1B. Here is the front of the modified fuse where our soon to be made former will be installed.

Fairchild Imagination
Fairchild Imagination

1C. Holding up our drawing to imagine what it’s going to look like. Does it look correct?
“Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.” Albert Einstein

Former Drawing and Copy
Former Drawing and Copy

2. If your using an obtained drawing or you wish to preserve your drawing, use a copier or all in one printer to make a copy of the area containing the part you want to make. In this case, I made a copy of my pencil drawing just in case I discovered and error and wanted to alter the drawing before I finished.

Fairchild Former Heavy Pencil
Fairchild Former Heavy Pencil

3. Heavily pencil over the lines we wish to transfer to the wood. I used a standard #2 pencil.

Fairchild Formula 560
Fairchild Formula 560

3B. There are multiple uses for Formula 560.

Fairchild Former Drawing Face Down
Fairchild Former Drawing Face Down

4. Place the drawing, heavy pencil down against your material. You will notice the grain is running the wrong way in this former. However, it’s just a jig for building the nose, it’s not intended to provide any structure. The nose of this model has many facets of 1/4″ thick balsa. Although I’ll leave the former in the model, it could be removed if I wanted too. As this model has a short nose needing weight up front, I’ll be leaving it in.

Fairchild Plan Pin Down
Fairchild Plan Pin Down

5. Place two pins through the paper into the wood to prevent the drawing from moving. I choose top and bottom locations. Notice you can see the drawing through the paper. Makes me feel like Superman, you?

Fairchild Nickle Rub Down
Fairchild Nickle Rub Down

6. Find something curved and smooth like a coin, I choose a nickle to rub the pencil into the wood.

Fairchild Lift & Inspect
Fairchild Lift & Inspect

7. Because we created a way to register the drawing to the wood, we can lift the paper up and look at our results as we progress. No danger of losing our alignment.

Fairchild Former Transfer Finished
Fairchild Former Transfer Finished

8. Ahhh, thats what I’m talking about! The drawing has new been transferred to our material. It will be easy to cut it out now.

Fairchild Former On The Bandsaw
Fairchild Former On The Bandsaw

9. Doing what the band saw does best.

Fairchild Drill Hole
Fairchild Drill Hole

10. Drilling for the Scroll Saw

Fairchild Former Installing on Scroll Saw
Fairchild Former Installing on Scroll Saw

11. Installing on the Scroll Saw

Fairchild Scrolling Along
Fairchild Scrolling Along

12. Doing the inside, what the scroll saw does best.

Fairchild Former Against Print
Fairchild Former Against Print

13. How does it look against the print?

Fairchild Former Goes About Here
Fairchild Former Goes About Here

14. The former goes in about this position.

Fairchild Former Positioned
Fairchild Former Positioned

15. Former positioned and ready for addition of next nose sheeting segments. Since we are working with a model that is already built, we elected to jig the next two formers to the front of the fuse. when the 1/4″ thick balsa segments are added from the front of the fuse to this former, many facets will be formed representing the nose of this model. Using this method, we only need to make the 3 sides of each sheet accurate, they can be allowed to extend past the former. We can cut them off and sand them down against the former as we go. After all plates in position, we’ll snap out all the scrap sticks used to hold the former in place. The sanding bars are banded tightly to the fuse sides so I could measure and put the former in the center. They make a great straight edge.

I thought solving the problems of making and installing this former would be interesting to readers and hope you made it this far into a very long post.

Story of the National Parks Service first aircraft in the National Parks Traveler

Stars And Strips, a Fairchild FC 2W2 at the target=”_blank”>The Virginia Aviation Museum.

Byrd's Fairchild
Byrd’s Fairchild

Admiral Byrd used the Fairchild FC 2W2 as a Aerial Photography Platform including in the South Pole.

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Balsa Kitchen? Killer RV Upgrades

Who hasn’t at one time or another considered converting a bus or some other service vehicle to an RV. You might enjoy The Travel Channels show Killer RV Upgrades. Find a Grumman Albatros converted to an RV complete with a balsa kitchen. (Chrome users may have to reload this page to view video player.)

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Converting A Model From Lipo to A123 (LIFE) Cells

Chris from Michigan Asks;

Hello Dave,
I would like to power my Ryan with A123 cells. I have been using a 9s 4p 6000mah Lipo pack to power a Hacker C50 motor.
If I understand things correctly, I believe that I need 4packs 6s 2300mah to equal the same watts and flight duration as the Thunder Power packs that I have been running.
Because of the cost of these A123’s, I want to be sure that what I am ordering is correct!

Chris,

To match duration of a 6000mah Lipo, you’ll need at least 6000mah in A123 which will be 3P. You’ll actually be a little over as the 2300mah A123 cells actually test most of the time around 2200, at 3P you’ll have 6600mah which should result in slightly more flying time.

I assume your 6000mah lipo is made up of 1500mah Parallel packs. So, 4 1500’s in parallel = 6000mah.

If what you really meant was your running 6000mah cells, 4 in parallel, then your pack size is 24000mah which would be about 11P or 11 A123 in parallel. I am not thinking you meant you had a 24000mah pack.

If your running 6000mah total in the airplane, and are thinking of running A123 in 2P for about 4400mah real world, this may be just fine. I generally only use the top 60% of a Lipo (70% max) on a routine basis. 60% of 6000 3600mah, 70% is 4200mah. I’m more comfortable running A123 cells a little deeper than Lipo’s as the risk of hitting BEC cut off cause me less worry. (Hitting BEC cut off is hard on Lipo’s) So, running a 4400 A123 down 80% is 3200mah. So, a 2P A123 should get close to the Lipo in actual use. However, your not running as much cushion between a solid end of flight habit and the bottom of the battery.

For matching running voltage, you’ll need 10 to 11S A123. I’d probably go to 11. At 12S, you’ll definitely have 3-4 more running volts. It will be like 9.8 Lipo or something like that.

To do conversion at nominal voltage, (# Lipos * 3.7) / 3.3 nominal of A123 = cell count.
To do conversion at full voltage: (# Lipos * 4.2) / 3.6 full voltage of A123 = cell count.

Nominal conversion is: 9 Lipo = 10.09 A123 cells

Full voltage Conversion is: 9 Lipo = 10.5 A123 cells.

Since you do most of your flying between full and nominal voltage I lean towards the full number for this estimation. 11 is the best choice. 10 you might notice a slight decrease in performance by your motors KV * volt reduction of the 10S pack. Right in the front of the pack, the 9S Lipo is 37.8v. Right in the front of a 10S A123 your full voltage will be 36v. So, KV X 1.8 = drop in top rpm. If your running a 500kv motor, that’s 900 rpm.

If you go with 11 cells, you’ll be starting out at 40.4v meaning your over the Lipo voltage by about 2.6v. So, you pick up (with 500kv motor) 1300 prop rpm.

Either choice means to get back to exact performance you had on Lipo you may need to alter the prop slightly, maybe an inch more pitch for the 10S A123 and an Inch less pitch for the 11S A123 or something similar to re balance things back out.

So, on balance, not knowing everything about the model and power system, I’d lean towards 11S. If you go 12S as your proposing, you’ll likely end up way over on RPM and Watts from where you were with the 9S Lipo pack. Important considerations here are if you mind a little more or a little less power (if the ESC minds more amps/voltage) and if you would need to change props, is there a convenient prop up or down that would suit the model and flying preferences. For example, if your running right at the edge of the ESC at this time and didn’t want to upgrade it, a slight decrease in power is acceptable, 10S becomes the obvious choice.

Another consideration not taken into account above is there can be a wide variation in quality of Lipo’s people are using out there. (not picking on Thunder Power, remarks for general readers of this post) Your current pack which may be performing just fine for the application may be worn and not really up to snuff compared to the original new condition. Thus if the current lipo has more voltage depression than it should, an A123 10S pack depressing less by some significant amount, could end up taching and watt metering out higher than the battery you are now using.

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