You reminded me of something I forgot to include. The required clearance depends a lot on the shock absorbtion arrangement also. Some planes have very stiff legs. Some are very soft and sink quite a bit just from added weight.
By the length of the plane I was referring to the distance forward between the wheels and the prop. On some planes with a very long nose you don't need to get much nose down to eat up all your prop clearance. On planes with less distance between the mains and prop you need to get much more nose down to hit the prop. Obviously, nose down is just one way to hit the prop, flexing the gear is the second so both need to be looked at together. The purpose of my post was to say that the FAA minimum is not a hard number if you have a shorter distance from the mains to the prop and stiffer legs. -------- Original Message -------- Subject: KR> FAR Prop clearance From: Larry&Sallie Flesner <flesner at frontier.com> List-Post: krnet@list.krnet.org Date: Mon, January 06, 2014 9:01 am To: KRnet <krnet at list.krnet.org> At 08:59 AM 1/6/2014, you wrote: >9" on a Citabria or Cub is not the same as 9" on a KR or other smaller >plane. When you have a larger plane with the prop many feet in front >of the gear you don't need to get the tail up to a very high angle >before that 9" turns into zero as you do with a shorter plane with the >prop not as far in front of the gear. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ I would agree that there are a number of homebuilts that don't have the recommended prop clearance. I would , however, respectfully disagree with the above statement. 9 inches is 9 inches in any type of airplane, nose wheel or tail dragger, on the ground in a level attitude. The SINGLE variable in prop clearance is the length of the landing gear, not the length of the airframe. Marty Roberts had an 0-200 swinging a 60" prop on a plans built KR2 with the 24" Diehl gear legs and had maybe 4 inches of prop clearance if he was lucky. My KR, same setup, prop size, etc., is stretched 24 inches and I have 9+ inches of clearance. The difference is that I'm using 30 inch gear legs (cut to 29 inches during fitting). The Corsair swung a GIANT size prop. Problem was they couldn't make the gear long enough for ground clearance and remain strong enough to support the aircraft in landing. Their solution, raise the fuselage by angling the wing down to the gear which enabled them to use a shorter gear length. So, regardless of the length of your airframe, build your gear to give you the prop clearance you want, whatever that happens to be. Larry Flesner _______________________________________________ Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org please see other KRnet info at http://www.krnet.org/info.html see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options
