chad500_0

All,

I am attempting my first scratch build. I have built kits for a number of years and I would say that I am excited by the idea of attempting my first scratch build. The first issue that I have already come across it this:

I had my plan enlarged at a copy center and I have found that the scale is some what smaller than the plan should be. Insted of a 48" wingspand it is 43 3/4". This is a texaco Klemm L33 plan and I have found that I like to look of the smaller scale. I still plan on using 3/4" trailing edge and the called for dimensional wood, are there other concerns that I need to be aware of?

I plan on building this right after my Simple Series ME 109 (it's looking good) and I am new to building without a step by step guide. I am spending each night with the plans to make my own vision of how it needs to be built. Any help oor insights are welcome.

chad

PS I posted this question on the "scratch build" forum and I have had only one reply.

Hueydriver

Chad,

For scratch builders, the Tile Print software is without a doubt the best tool in your inventory. It allows you to scale any plan (as long as you have a JPEG, GIF etc) to whatever wingspan you want. I used it yesterday to scale up a vintage design. Here's the link:

http://www.blackflight.com/

Kirk

digital_trucker

I assume you're copying an existing paper plan. Many copiers don't really scale all that accurately. What I've done in the past is this; since I know what % I'm scaling up or down, I draw a line on a sheet of typing paper so that the length of that line when it's scaled equals 1".

For example, if I'm enlarging 25%, I draw the line .8" long so that the final copy will be 1". The formula to determine the line length that you originally draw is 1/1.x, where x=the scale percentage. The above example gives us the equation 1/1.25=.8 which when scaled up 25% ends up with a 1" line. At any rate, when you draw that line .8" long, you then experiment with the copier until you reach the final 1" line you need...then you make your copy of the plan.

If you're scaling DOWN the formula is 1/x, where x= the scale percentage. Let's say you want to shrink a plan so that it's 75% of the original size. Using this formula we get 1/.75=1.333. You draw your line 1.333" and play with the copier until you get your 1" line, and copy your plan.

As far as wood size goes, enlarging and reducing plans often means you have to re-engineer the construction. Mostly it's just good for the original outline. Your mileage may vary, of course. Best thing to do is take a good look at the copy and use experience to determine what to do. If you've built a number of kits before you should have a good idea of what size wood works best given the size and type of the model.

I hope all this rambling and windy pontificating makes sense. Most likely I'm doing it completely wrong, but it works for me

combatpigg

My Feedback: (3)

If the project is simple enough to be built from a quick sketch, all you need to do is come up with a mutliplier. If the otiginal model has 50 inches of wing span, and I want to build a 30 incher, then just multiply all original dimensions by .6

rainedave

My Feedback: (1)

Chad, for some reason the setup you used printed the plans at about 91% of full size. A 9% difference in wood dimensions is not enough to matter on a small model like this. 9% of 1/8" thick balsa is a pass or two with sandpaper. On a large model - like 1/4 scale, for example - 9% would be more of an issue. But, 9% of 1/16" sheet is probably within the milling tolerances of the wood. Humidity is probably a bigger issue with small wood sizes.

It's probably a good thing that you're building a smaller scale version, anyway. 1/2A Texaco models are designed to three requirements: a minimum 8oz wing loading, an maximum 8" prop and a reed valve .049 engine. They are typically in the 47" to 50" span range. They are scaled as large as possible to meet the wing loading rule and still be able to climb to altitude on the legal engines. They are not designed to be flown as sport models. They are designed for duration and riding thermals. To make the average 1/2A Texaco design into a sport model would require using a .10 or .15 engine. By scaling it down to 43" you should be able to get decent scale-like performance with an r/c .061 like the Wasp.

Bipe Flyer

I use Tile Print for all my plans.

BMatthews

Really?! Now why on earth would you want to do THAT!

Raindave makes a very good point. It will be a hotter sporty model if that is your intention. But if you are looking for more of a climb and glide thermal hunter then you'll want to get the plans back up to the proper size.

These models typically come in at around 17 to 20 oz. At that weight they may be lazy with the 8 inch prop but if you go down to a 6x3 then they acatually turn into a pretty hot flyer for the duration of the engine run. And you cn split the difference by going with something like a 7x3 so there's lots of options.

It all just depends on what you're after.

Since the shop messed up they actually owe you a set done to the proper size that you requested. You might want to hit them up for a new copy to the right size depending on what your intended flying style for this model will be.