There are three things you can use to increase the speed. Reduce the parasitic drag. Reduce the incuded drag. Increase the HP.
The parasitic drag can be reduced by paying attention to detail with clean lines, and fairings to clean up the airflow. Induced drag is a function of the weight your wing area has to lift. Lift induces drag. The lighter you build, the less your wing has to lift, and the less induced drag you will have to overcome. HP is pretty simple, but mounting a bigger engine with more weight isn't always the answer. HP probably has the least effect out of the three items listed here. HP will affect take off performance and rate of climb much more than overall speed. When I changed from a tired C-85 to a high compression O-200, that was good for only 7 knots. As for gap seals, wheel pants, etc., Larry and I both picked up 15 mph with the RV series wheel pants over our 5:00x5 tires. In my book, that's pretty darned significant. A quick check of the charts with HP and a variable for prop inefficiencies will show that many KRs have less than 2 sq ft of flat plate area of parasitic drag. With that tiny bit of parasitic drag, any improvement you can do to the airflow makes a significant impact to the performance of the plane. I tested gap seals on my Diehl skinned RAF 48 wing and found no advantage at all, although the guys with the new wing report that gap seals make a significant difference for them. As some of the guys on line may have noted, my KR is undergoing an aerodynamics overhaul this summer and should come out sometime this fall as a cleaner faster flying machine. Jeff Scott -- "wilder_jeff Wilder" <wilder_j...@msn.com> wrote: Can someone explain to me why it is that there is such a gap in the top end speed of KR's... ( HP aside ) There is a guy here in Longmont Co that has a KR... says he can do over 200 in it... ( not for me ).. but he can, running an O200. He says his plane is about 500lbs built to the plans with a VW conversion.. the reported speed is 180.. but yet other report a top end of only 120-140. Mark .. have you/ had you opened it up to see what she could do? I wouldnt think that wheel pants and wing gaps could add 12 mph.. man.. I think I'll order a dozen... get an extra 144 mph out of her... :)just need find a place to glass them to So is the top end speed more of a function of weight/HP apposed to just HP everything else being equal? -Jeff by the way.. pulled a good piece off my mold tonight. I'll still have to sand the snot out of it... and fill it with something. 2 layers of mat 1 layer of 3.2 oz cloth... and about 3/4 of a gallon of impact resin. I would guess it weighs about 10 lbs or so.. This piece is strong enough to be free standing. I have reinforced it with some honeycomb looking material, it looks like a sponge before you lay it up.. man does suck up the resin.. but MAN is it stiff. I cut 2 in strips ... and placed them ontop of the mold after I had pulled the piece off.. layed them up.. and placed the piece back on mold to cure. Part Doux... this round goes on the plane :D _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
