Herbert Fürle's German KR2S


Herbert Fürle's German KR2S


Here's some info about me and my "airgrafia". I'm 54 and married with a nonflying-but very comprensioneful wife (of course) since 1968,I have a daughter and a son-only passengers-and a 4 year old grandson-my safety pilot for the future?! I learned sailplaneflying when I was 14. Since than I flew approximately 1200 hours with different planes-from scoolgliders up to highperformance composit- gliders like the Hornet or the famous Libelle-L/D 40:1. 1984 I started to construct my first homebuilt, a FFP202"Koala". I flew the little "Piper" a few years and started building my Kitfox IV( I think you have the Pic.?) in 1993. My successful maidenflight was in the fall of 1995 1994.

I chanced to meet Roy Marsh at Sun'nFun and I was so impressed by his KR2S that I decided to start building me this plane immediately after I have finished my Kitfox-I do it!

After I have finished my "Banana boat" and all my spars I made a break(maybe a little listless)-Exactly in this time I heard from you and got all the new info about the new Airfoil and all the good changes on the KR2S-what a chance. I immediately continued my project with all the goodies- just at the right moment I think.

I use-as you can see on the pic's,- the AS5046 and lengthened my HS 3" on both sides. I've done my woodwork with european pine(about 12% stronger than spruce but also a little heavier)and birch plywood. I glued it together with UHU-PLUS ,comparable with EpoxyT88. The foam I use is polyurethan ,a little tighter as recommanded by RR. The glass and resin I use is all aircraft-certified and in the same size as recommended by the construction manual it's also used by Schempp-Hirth and Schleicher.


Pic #1gives an image how the KR2S looks from the side.


Pic#2 demonstrates the installation of the gearatachbracket from Dan Diehl, the fit of the spars, both seatbacks,the temporary installed aftdeck ,the fueltank-dashboard-combination naturally removeable and the pedals without brake accessory.


.On Pic#3 you'll notice the additional 3" span to the HS and how I designed the tip of the HS, probably I add another hinge at the outboardside.Further you can see how the aftdeck-made from foamplanks ,shaped and glassed in the descriped manner by RR-fitsto the tailgroup. The following pics gives an impression of my solution how I installed the seats and the controls(most of them standard exept the Joystick).












Below is an update, December 2003

My Kr did'nt sleep and I was very busy with my project as you can watch on the newest pics .I had my first inspection this summer and I continue to finish my Plane probably next year.

The yellow Engine you can see is a typ 4 Porsche engine which was restored by me and basicly I planned to install this engine.But I changed my mind and now install -as you can see on some pic's- a Rotax 912 S. The one you can see on a pic is only temporary installed and a poor mokup for better handling .

The pic's shows how I did the roots and wingtip on my outer wings.further you can watch the progress of the canopyframe and the canopy also.The canopy is basicly used on a german motorglider and the thickness is about 1/8 inch.(3mm).You can also recognice the tailwheel (an oldone RV4).

The cowling you can see is from a 912 equipped Cherry (similar to the Kr2S).I've got the molds from a friend and I've glassed them for my KR. They need minor changes to fit to a KR. One picture shows how much space i had in the fabric-hangar of my friend norbert-a great mentor of my project.He is the one who made all the machined parts for my Kr.















You will notice my solution of installing a "springtrimsystem" for the elevator into the joy-stick.With the trim lever you change the sticklevel -a very simple but effective way, I think. I installed also two springwires to give you the feeling of "inputforce" for the aileron axis due to the very light control forces. The springs also moves the stick to its neutral position.












This is the trailer i designed. From open the trailer to almost ready to fly the kr it takes about twentyfive minutes.So i can save the expensive cost's to hangar the kr.some details showes how the wings and the fuselage locks in the trailer.the heavy duty canvas- top protects the kr very well and is very light ,compared to a hardtop made from metal or composite.










I made a small middleconsole to cover the controllcables, to reinforce the attachpoints for the belts and of course to give a comfortable armrest for a gentle control input.





The biggest adventure was to finish and paint the outer wings. The nettoweight of one outer wing (without the aileron balance weight )is 39,3 pound.The painted outer wing weights about 41.7 pound .

The paint i used is a two component polyurethan-acrylic - paint which is called "PUR-A" paint and is mostly used for big industry-machines.I've bought them direct from the manufacturer and it was very cheap.(one and a half gallon took me about $45.-)













I built the seats like slingseats.I made fittings for the shoulderpart of the seats and in front of the mainspar also.The adventure of this design is ,i can adjust - and remove the seats very quick.





The center panel with tubes for the fuelgauge on both sides is fixed to the removebal "fueltank-dashboard". The sidepanels are conected with three small shockmounts on each side of the centerpanel.From the center panel down to the mainspar i built a slim console which support the dasch and carry some small switches or instruments and the lower part of the fuelgauge. One picture showes the throttle quadrant i built and the fittings which locks the foreward edge of the seats.






The toebrake-pedals are milled from 7075 aluminium and only mounted on the pilots side.you will recognize how simple it is to adjust the controlpedals within a 2 inch range.










Here you might see, how I desiged the naca-airvents for the cockpit,integrated in the covers for the canopy-frame,where the frametubes slide out from the dashboard. When the canopy is closed the covers close the cutout for the frametubes.

















UPDATE, November 2010
Here are the newest pictures of my Kr. I hope to finish my Kr next year. A friend of mine over here in germany had his first flight in his kr2 a couple of weeks ago and he is very satisfied with the result.He registrated his plane as an ulralight in france. To fullfill the rules in france for ultralights, he built his wings rectangular (like a RV4). He uses the RAF 48 airfoil and made the ailerons and flaps in your manner.With these configuration he lowered the stallspeed down to approximately 47 mph.




































































That's for the moment.Thanks a lot.sincerely Herbert

PS.:If anyone has questions, feel free to contact me at my Email address, KR2SL@aol.com.