---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Wed 07/23/08: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:12 AM - Re: Re: Drooping FireFly Flaperons (pj.ladd) 2. 05:01 AM - Re: Re: Drooping FireFly Flaperons (gary aman) 3. 07:03 AM - Re: Weight and Balance? (TheWanderingWench) 4. 07:57 AM - Re: Re: Dipole antenna from co-ax (Denny Rowe) 5. 09:47 AM - excellent on-line weight and balance calculator (Scott Perkins) 6. 10:03 AM - Re: Weight and Balance? (Dana Hague) 7. 10:54 AM - Re: Weight and Balance? (Jack B. Hart) 8. 12:29 PM - Re: Weight and Balance? (lucien) 9. 12:37 PM - Re: Weight and Balance? (The Kuffels) ________________________________ Message 1 _____________________________________ Time: 03:12:58 AM PST US From: "pj.ladd" Subject: Re: Kolb-List: Re: Drooping FireFly Flaperons I for one would approach aft CG limits very carefully.>> Hi, I am with you on that, all the way. Aft Cof G is apt to be a killer, literally. Cheers Pat ________________________________ Message 2 _____________________________________ Time: 05:01:03 AM PST US From: gary aman Subject: Re: Kolb-List: Re: Drooping FireFly Flaperons One last note on the w&b thing.I raised the leading edge of the horizontal stabilizer 1 1/4" on my firestar and spring loaded the elevator favoring nose down with an adjustable trim .It could be flown hands off IN CALM AIR.But it was like crossing a boats wake, only longitude wise, with a quick pitch up then back to level, in rough air,and during a maximum effort slip,putting the stick up in the corner with opposite rudder,when the elevator lost effectiveness it would pitch up dramatically.I'll never forget the first time THAT happened.I added some nose weight to bring it into mid-range cg and it became a much more comfortable aircraft .My MK-3 is similarly afflicted.I'll carry the weight. G Aman MK-3C Jabiru 2200 350 hrs ----- Original Message ---- From: pj.ladd Sent: Wednesday, July 23, 2008 6:10:17 AM Subject: Re: Kolb-List: Re: Drooping FireFly Flaperons I for one would approach aft CG limits very carefully.>> Hi, I am with you on that, all the way. Aft Cof G is apt to be a killer, literally. Cheers Pat ________________________________ Message 3 _____________________________________ Time: 07:03:48 AM PST US From: TheWanderingWench Subject: Re: Kolb-List: Weight and Balance? John - Your comment on W & B was a real eye-opener...it reflects my own experience, but is something I've never heard anyone talk about. When I did the original W & B on my Drifter, the A & P (also an experienced ultralight builder and pilot) guided me to putting 60 lbs. of lead in the nose, since I am a true ultra-light pilot at 105 lbs. I flew with that weight for years - then had to re-do my W & B when I added an electric starter aft. Showed I should put MORE lead in the nose. I was uncomfortable with that (most of the other pilots are trying to shave off ounces and here I'm adding pounds!) and took it all out, putting some tools up front for easier access. It didn't fly discernably different! Even when I'm fully loaded with my camping gear, which also is aft of cg. Since weight and balance is a matter of physics - how come we've got such different results than would be expected? Is this akin to the "a bumblebee can't fly"? Arty Trost Maxair Drifter Sandy, Oregon > > John Hauck Wrote > > > Weight and balance of a Kolb is one of those unique > areas. There are folks > > out there still flying Kolbs with lead in the nose to > make the paperwork > > work. I put a 11+ lb tailwheel on mine for a couple > reasons. Primarily, > > the Maule Tundra Tailwheel, 8" pneumatic with > tapered roller bearings in the > > pivot, is the only tailwheel I could afford that will > stand up to the weight > > of the tail on my MKIII. The other reason was to > demonstrate Kolbs don't > > particularly have an aft cg problem, if built, more or > less, according to > > the plans. In addition to the heavy tailwheel and prop > on a 4" extension, > > I fly with 150 lbs of fuel and 100+ lbs of cargo aft > of the cg. I do get > > some offset from my modified main gear being moved > 8" forward, but not much, > > since they are very close to the cg. > > > > > > > My Mark III manual says the airplane should balance between > 25% and 35% wing chord which is 16.5 to 23.1 inches behind > the leading edge of the wing. > > I am a light pilot at 155 ready to fly so my weight and > balance calculation says I need I 10 lbs in the nose to > make the aft limit at 23.1 inches. Or a minimum weight of > 177 for the pilot with no ballast. > > So if I am reading this right you are saying to forget > about the Weight and balance and do not add the weight? > > With no ballast my cg would be at 23.95 or about and inch > aft of the aft limit. > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=194430#194430 > > > > > > > ________________________________ Message 4 _____________________________________ Time: 07:57:17 AM PST US From: "Denny Rowe" Subject: Re: Kolb-List: Re: Dipole antenna from co-ax Boyd said, > Use 50 ohm coax..... the 75 ohm stuff is for cable tv. Or xmitter > designed for 75 ohm loads. > Your transmitter is designed for 50 ohm coax and matched to an antenna > tuned > to a 1 to 1 match,, which is a 50 ohm impedance. .. > Try to stay away from the coax with a solid core center wire unless it is > for an installation that will have no movement. > > Boyd Young > Kolb MkIIIC > 530 + hours > Boyd, You took these word right out of my mouth! Its all correct info. Denny Rowe, Mk-3, PA, Electronics Tech. ________________________________ Message 5 _____________________________________ Time: 09:47:57 AM PST US From: Scott Perkins <2scott@bellsouth.net> Subject: Kolb-List: excellent on-line weight and balance calculator go to this website and select the "SuperCalc 7.0" http://chrusion.com/BJ7/ It cannot be made any easier than this Scott ________________________________ Message 6 _____________________________________ Time: 10:03:41 AM PST US From: Dana Hague Subject: Re: Kolb-List: Weight and Balance? At 09:58 AM 7/23/2008, TheWanderingWench wrote: >Since weight and balance is a matter of physics - how come we've got such >different results than would be expected? Is this akin to the "a >bumblebee can't fly"? The allowable c.g. range is set between two limits. Go too far past the forward limit (nose heavy) and you may not have enough elevator authority to raise the nose at low speeds, which makes for hard landings. :) Go past the aft limit (tail heavy) and the airplane gets less stable... go too far and it becomes dangerously unstable. Within extreme limits, how much stability is required depends somewhat on the aircraft's mission (you want a Cessna to be more stable than a fighter or an acro ship) and also on the pilot's preferences. Even a neutrally stable plane can be OK, if the pilot can handle it and is expecting it. Like everything else on an airplane, the limits are set to insure some safety factor. Depending on the target pilot audience, the designer may be more or less conservative when setting the limits. That's the primary thing governing the limit. But there are other things as well. Gary mentioned a sudden pitch up when slipping hard; that's one example. Or, very likely, a plane might fly just fine in most cases with an aft limit, but then be unable to recover from a spin, or some other odd flight condition. It's one of the reasons that test pilots are well paid. Fly your plane past the aft limit and YOU are the test pilot. -Dana -- Everyone who lives dies; yet not everyone who dies, has lived. ________________________________ Message 7 _____________________________________ Time: 10:54:43 AM PST US From: "Jack B. Hart" Subject: Re: Kolb-List: Weight and Balance? At 06:58 AM 7/23/08 -0700, you wrote: > Arty & John, If you wish to deviate from the per scribed CG range for your aircraft, it would be best that you follow the testing procedure as set up by the FAA and report back the results. Check: www.faa.gov/library/manuals/aircraft/media/ac90-89a.pdf Especially important is page 57 that lists "Maximum Gross Weight Tests" If you don't want to do this and prove that your new aft CG limit is ok, then I suggest that you climb to an altitude or 10,000 agl, and perform a departure stall. Then report back to the List as to how it went. Fly safe and know your CG limits. Jack B. Hart FF004 Winchester, IN ________________________________ Message 8 _____________________________________ Time: 12:29:35 PM PST US Subject: Kolb-List: Re: Weight and Balance? From: "lucien" Dana wrote: > At 09:58 AM 7/23/2008, TheWanderingWench wrote: > That's the primary thing governing the limit. But there are other things > as well. Gary mentioned a sudden pitch up when slipping hard; that's one > example. > For what it's worth, my titan exhibits a pitch-up tendency in a max-effort slip when near the aft limit as well. When solo with full gas, I'm right near the aft limit listed for the plane and the nose comes quite a ways up in a max-effort no-power slip (doesn't hit stall AOA tho). I notice this reduces as the flight goes on and some gas gets burnt (or with a copilot in the back seat max-effort slips are no problem). Other flight characteristics are kind of nice with an aft CG tho - stalls are very gentle and it just mushes forward (still nice with a copilot but with a more abrupt stall break and a bit more pitch-over) and very high AOA, slow flares are possible with very light elevator pressure. I am working on a ballast system to conveniently add ballast when solo tho since the pitch-up with slips would be nice to fix.... My FS II flew slightly nose-heavy and it accordingly didn't exhbit any pitch-up at all in a slip.... LS -------- LS Titan II SS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=194577#194577 ________________________________ Message 9 _____________________________________ Time: 12:37:01 PM PST US From: The Kuffels Subject: Re: Kolb-List: Weight and Balance? One point which should be reiterated. In the US it is the *builder* of an experimental who sets the CG limits, not the plans designer or kit supplier. What we should do is set the CG near the middle of the suggested range for early flights. Once familiar with the aircraft, the builder should use some of the 40 hour test period to determine the CG limits for *his/her* airplane. Ballast forward (in small increments) until slow speed elevator authority starts to go away. Set the forward limit back a little. Ballast rear (in small increments) until stability starts to go away (particularly in turbulence). Set the aft limit forward of this point a little. Also check stall characteristics at each step. Different pilot perceptions of approaching unsatisfactory handling will result in different limits. So will differences in building techniques. My understanding is it is difficult to get a plans conforming Kolb to be loaded in an unstable aft condition. But no-one knows for sure with any given homebuilt until the limits are determined by test. Tom Kuffel, CFI EAA Flight Advisor Whitefish, MT Building Original FireStar ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kolb-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kolb-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kolb-list Browse Digests http://www.matronics.com/digest/kolb-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.