Specs and Mods
		KR-2		KR-2S		KR-2XL
Length		14'-6"		16'		18'-6"
Wing Span	20'-8"		23'		26'
Wing Area	78 sq.ft.	88 sq.ft.	100 sq.ft.
Gross Weight	900 lbs.	980 lbs.	1400 lbs.
Empty Weight	480 lbs.	520 lbs.	750 lbs. (est)
Useful load	420 lbs.	460 lbs.	650 lbs. (est)
Stall speed	52 mph		52 mph		54 mph (est)
Maximum speed	200 mph		200 mph		200 mph (est)
Cruise speed	180 mph		180 mph		160 mph (est)

The KR-1 and later the KR-2 were designed to be small, lightweight, and easy to build. Unfortunately, there is not enough room for really tall pilots.

As the design matured, more and more people built them larger, until the KR-2S was introduced. This added an additional two inches of leg room to between the main spar and the fire wall, as well as an extra 14 inch bay behind the rear spar. In addition, very few of the completed examples turned out as light as the prototype.

When I deceided to build a plane based on the KR, it was in large part because it is a design that is easy to modify. I am very tall (see a brief bio) and needed something large. I do not recommend that anyone make the changes that I did. It is a lot of extra work and requires careful thought and analysis. Every change affects everything else.

Starting from the basic KR-2S plans, I added an additional 5 inches in front of the main spar. This is counterbalanced by an additional 6 inches behind the rear spar (an extra inch in each of the bays). To maintain everything in balance, I am using a 3 gallon header fuel tank, supplied from two wing tanks (32 gallon total) by an electric pump. The pump will run constantly with overflow returned back to the wing tanks. I also added 3 inches to the width, and one inch to the heigth.

The extra size and weight required additional wing area and span, this in turn would mean more weight, which leads to a slightly stronger structure. I performed a comparitive stress analysis that showed the fuselage wouldn't need much changing. I did add a bottom longeron doubler that runs from the firewall to the back of the baggage area. I also added an additional doubler to the top longeron, over and above that currently called for in the plans.

The main modification for strength is in the wing. The main spar center section is solid, instead of the built-up called for in the plans. The outer section main spars are correspondingly stronger. The main gear is my own design, based on the Dan Diehl gear. I sized it for a 5G static load at the 1400 pound gross weight.

Other modifications include:

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