---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Wed 03/31/21: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:25 AM - Thrust line (posting for a friend) (chic) 2. 01:42 PM - Re: Going to a 72" prop (Richard Pike) 3. 07:58 PM - Re: Kolb-List Digest: 2 Msgs - 03/30/21 (artdog1512) ________________________________ Message 1 _____________________________________ Time: 11:25:39 AM PST US Subject: Kolb-List: Thrust line (posting for a friend) From: "chic" Hello chic. Would you mind posting this message for me? I seem to have lost my ability to get replies in although I receive the digest. Thanks. What you said is absolutely true about pointing the thrust line down. Maybe most pusher owners know this but I didn't and I didn't think it was intuitively obvious that pointing the thrustline down would add up thrust. When I purchased this pusher with an 80 horsepower 912, both the owner and the builder said that it had issues with an inability to trim at high power settings and difficulty in rotating on takeoff without easing off on power. They thought I should be going back to a lower powered engine. I looked at it and thought the engine was pointing down too much and so raised the thrust line to compensate. That caused so much back pressure on the stick that I could barely complete the flight even with full up trim. It was then I started digging around to find out how things really worked and the best source of information aside from a couple of people who knew what was going on, was at model airplane sites which had good diagrams showing the effect of thrust line relative to the centre of gravity. This got me adding down thrust and I now have, after about a 6 degree change, an aircraft where I can go from low-power to full power with no change in trim on the stick. Mine was the first and maybe only one with a 912. Aircraft is a Skywatch. Peter Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501169#501169 ________________________________ Message 2 _____________________________________ Time: 01:42:03 PM PST US Subject: Kolb-List: Re: Going to a 72" prop From: "Richard Pike" All done and flying great. Had a few teething issues: Initially started out with an extra 3/8" motor mount spacer at the rear, giving it a bit of downthrust to counteract any possible pitch over tendencies. Flew it four times that way, evaluating handling while trying to get the Warp Drive prop pitched properly. (Made me really appreciate the Ivo's ultra simple prop adjustment method!) Short version: the airplane simply felt wrong. Constantly fighting it as it kept trying to nose up at most every throttle setting, plus on final with minimal power, it just did not feel right. Removed most of the rear spacer, now it handles just like it always did, deviation from stock thrust angle is two extra 1/16" washers on top of the rear Lord mounts. Spent one afternoon playing with brass shim stock between the prop hub and the gearbox prop flange, finally got all three blades tracking within 1/16" of each other. Spent several days trying to get the prop pitched for a 6300 rpm climb and a 6500 rpm max in level flight. Finally got within 50 rpm and called it quits. Plugs look good, EGT gauges were lying to me. The new dual EGT gauge arrived today, no hurry putting it in, wx is rainy today, uber windy tomorrow. Anyway, everything is now as it ought to be, it runs smoother than it ever has, and the climb rate is typically right at 1,000'/min solo. Looks like normal cruise is going to be about 53-5400 rpm at 65 mph. And boy is it quiet! Now I need a pretty day so I can take some pictures of that old 2-seater trike, it's 582/w electric start, B box, BRS, and my 68" Ivo, get that thing sold and out of the hangar. $3k if you guys know anybody looking for such. Thanks for the suggestions & advice along the way. -------- Richard Pike Kolb MKIII N420P (420ldPoops) Kingsport, TN 3TN0 Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501172#501172 ________________________________ Message 3 _____________________________________ Time: 07:58:47 PM PST US From: artdog1512 Subject: Kolb-List: Re: Kolb-List Digest: 2 Msgs - 03/30/21 Time: 05:29:33 PM PST US Subject: Kolb-List: Re: too fat ..... From: "chic" Your biggest issue with the Firestar 2 and a heavy pilot is going to be a f ar forward CG.We have the same problem. I have a FIrestar 2 and I weigh 250 and am 6'4". How big are you? i'm 6ft... i have only one seat in the cockpit. (2) 5 gallon tanks under th e engine. i just wondered what the maximum weight is for the cockpit? ..... ......... i figured that since the FS 2 is made for (2) people one heavy pe rson shouldn't be a problem with weight and balance.. i don't know=C2- ------------------------------------------------------------------------------------- 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.