# Scaling up a Part 103 design to LSA?

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#### Brohawk

##### Well-Known Member
I've been searching and trying to decide on a 2-place LSA project. In my wandering on the internet, I found the T-100D ultralight. It's a pretty cool design, and a thought popped into my noggin (which my wife would tell you can be dangerous).

The T-100D is a wood airplane designed to come in under the 254 pound Part 103 limit. Would there be a general rule-of-thumb for scaling such an airplane up to make it a two-place with around a 100 HP powerplant? Such as, if the dimensions were generally increased by 50% (as an example), would the increased dimensions of the spars, longerons, etc. result in a proportional increase in strength?

With the design weight of 254 pounds, if scaling it up and adding a bigger motor added 350 pounds (to 600#), but the added strength allowed the gross to go up to the LSA limit, it could be a very nice cruising ship for two.

You've probably discerned that I'm not an engineer, nor do I play one in the movies. I just get ideas, but don't have the math skills to take them anywhere. If nothing else, it could lead to an edifying discussion...

#### Autodidact

##### Well-Known Member
There is a British designed Microlight that is almost exactly what you describe - forgot what it was called though, sorry.

Well here it is, the Streak Shadow - nice plane, I always thought:

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#### Topaz

##### Super Moderator
Staff member
Log Member
In explicit answer to the original question, no, there isn't any "rule of thumb" for this - essentially you'd need to redesign the entire airplane, and the result would only look like the ultralight original.

As far as I've ever heard, though, the Streak Shadow that Autodidact shows above is pretty tried-and-true, but as far as I know, is out of production and no plans were ever available. I imagine one turns up in eBay, Trade-a-Plane, or Wings and Wheels every now and again.

#### etterre

##### Well-Known Member
What drew you to the Mariah?

If you're looking for a twin boom pusher with 2 seats, the ION might be a good choice.

Ion Aircraft

It's not wood, but that could be less hassle than doing your own design.

#### Brohawk

##### Well-Known Member
What drew you to the Mariah?

If you're looking for a twin boom pusher with 2 seats, the ION might be a good choice.

Ion Aircraft

It's not wood, but that could be less hassle than doing your own design.
That ION is a slick airplane! Doesn't look like it's available yet. The website said they're not even taking deposits yet because they are still developing/testing.

I'm having to go with a plans-built project, because I have more time than money.

If someone with the skills/knowledge took this concept and developed it, there could be a market. Unfortunately, that's not me. =(

#### etterre

##### Well-Known Member
There is one Ion flying, and they did say that they wanted "beta testers" for the first few... So there might be a handful being built...

I hear you on the plansbuilt thing... I don't know how much \$ you have to spend in one go, but you may want to consider picking up a "wrecked" 2 place Kolb or similar... If it was N#-ed in the past, you could rebuild it and possibly stay in your budget