KR> weight and balance
My KR was out of the CG range until I sat in the seat which brought it to within the CG. range. ?I always kelp a little weight to throw in the back to help with CG. From: Mark Langford via KRnet To: KRnet Cc: ml at n56ml.com Sent: Monday, April 4, 2016 1:43 PM Subject: Re: KR> weight and balance Chris Prata wrote: >If 35% aft from the leading edge (at mean average chord point) is too far aft, >what is the commonly accepted safe limit and where in your experience does she >fly best? There's some ambiguity there, as the plans call for 8"-16" from the leading edge of the stub wing, and the range is quoted as 15%-35%, and 20% of 48" is 7.6", so the numbers don't jive. But let's say take 2" off of the 16" for simplicity and call it 8" to 14" for an "amended" CG range, then check the max forward loaded condition (lightest pilot and full/empty fuel, depending on where your tanks are).? Then calculate worst case with heavy passengers and aft-most fuel situation? and make sure you're nowhere near the aft end of the range, adjusting as necessary to get that range situated toward the middle, or biased toward the front.? Generally speaking the further aft the CG is, the less stable it will be.? There are few downsides to a forward CG, being able to lift the nosewheeel for rotation being one, and having to crank in some nose up trim (extra drag being the other.? The downside to too far aft is that the plane is a handful to fly, or, it kills you shortly after takeoff! N56ML is slightly forward in the condition that I usually fly it in, with half fuel, me as pilot, and the usual 20 lbs of crap I carry (tools, spare radio, camera, etc) sitting on the seat.? I've put some pretty heavy people in there and it gets a little light on the stick, but not dangerous, and most people that've flown my plane would call it quite reasonable.? N891JF was set up by Jim Faughn to be right on the forward end of the range with full fuel and him as pilot.? Needless to say, on my first flight, I took off with neutral trim and flew it up to cruise altitude that way.? Then I started checking control reactions and when I let go of the stick it immediately nose dived!? That's the downside...it needs trim cranked in.? That won't kill you though.? I have since added a few things aft (flap, backup battery, APRS, ELT), so it's a little more aft, and I noticed yesterday that my previous landing after a long cruise back home, the trim tab was level with the elevator, so I'm flying it "typically" with no up or down trim now, and it's quite fine...but the heaviest person I've carried is my 100 pound daughter! See http://www.n56ml.com/wb/index.html for more on what happens if you go too far aft.? Been there, done that, and don't want to repeat it! Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com ___ 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
KR> weight and balance
It's quoted as 15 to 35 percent of the mac...which I believe is 41 inches for the stock kr2...less for the kr2s. The point I make is that the location of the mac is very easy to change in relation to the stub wing...the as5048 has spar locations that move the mac...and cg range forward about a half an inch. https://sites.google.com/site/mykr2stretch/ https://sites.google.com/site/mykr2stretch/parts-for-sale
KR> weight and balance
mark if 35% aft from leading edge (at mean average chord point?) is too far aft, what is the commonly accepted safe limit and where in your experience does she fly best? > To: krnet at list.krnet.org > Date: Sun, 3 Apr 2016 19:28:49 -0700 > Subject: Re: KR> weight and balance > From: krnet at list.krnet.org > CC: ML at N56ML.com > > > Gary wrote: > > > From my plans, the CG is 15% to 40% of the wing chord. That was the old > > wing. Is it the same with to AS5048 wing? > > I don't ever remember seeing that number before. Is that for a KR1, or just > an early set of plans? My plans also say 15%-35%, and that's the range that > extends too far aft to be safe (according to an analysis by Richard Mole and > also experience by pilots). The AS50xx series airfoils are designed to have > a similar lift coefficient and range (15%-35%) as the RAF 48 (minus those > aft two inches). > > Mark Langford > ML at N56ML.com > http://www.n56ml.com > > > ___ > 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
KR> weight and balance
Chris Prata wrote: >If 35% aft from the leading edge (at mean average chord point) is too far aft, >what is the commonly accepted safe limit and where in your experience does she >fly best? There's some ambiguity there, as the plans call for 8"-16" from the leading edge of the stub wing, and the range is quoted as 15%-35%, and 20% of 48" is 7.6", so the numbers don't jive. But let's say take 2" off of the 16" for simplicity and call it 8" to 14" for an "amended" CG range, then check the max forward loaded condition (lightest pilot and full/empty fuel, depending on where your tanks are). Then calculate worst case with heavy passengers and aft-most fuel situation and make sure you're nowhere near the aft end of the range, adjusting as necessary to get that range situated toward the middle, or biased toward the front. Generally speaking the further aft the CG is, the less stable it will be. There are few downsides to a forward CG, being able to lift the nosewheeel for rotation being one, and having to crank in some nose up trim (extra drag being the other. The downside to too far aft is that the plane is a handful to fly, or, it kills you shortly after takeoff! N56ML is slightly forward in the condition that I usually fly it in, with half fuel, me as pilot, and the usual 20 lbs of crap I carry (tools, spare radio, camera, etc) sitting on the seat. I've put some pretty heavy people in there and it gets a little light on the stick, but not dangerous, and most people that've flown my plane would call it quite reasonable. N891JF was set up by Jim Faughn to be right on the forward end of the range with full fuel and him as pilot. Needless to say, on my first flight, I took off with neutral trim and flew it up to cruise altitude that way. Then I started checking control reactions and when I let go of the stick it immediately nose dived! That's the downside...it needs trim cranked in. That won't kill you though. I have since added a few things aft (flap, backup battery, APRS, ELT), so it's a little more aft, and I noticed yesterday that my previous landing after a long cruise back home, the trim tab was level with the elevator, so I'm flying it "typically" with no up or down trim now, and it's quite fine...but the heaviest person I've carried is my 100 pound daughter! See http://www.n56ml.com/wb/index.html for more on what happens if you go too far aft. Been there, done that, and don't want to repeat it! Mark Langford, Harvest, AL ML "at" N56ML.com www.N56ML.com
