---------------------------------------------------------- Kitfox-List Digest Archive --- Total Messages Posted Sun 07/03/11: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:13 AM - S5 Trim and control forces (skyring) 2. 03:29 AM - Re: S5 Trim and control forces (Lynn Matteson) 3. 07:38 AM - RPM/912 (rtmarshall) 4. 08:38 AM - Re: RPM/912 (Roger Lee) 5. 11:34 AM - Re: S5 Trim and control forces (Michael Gibbs) 6. 12:14 PM - Re: RPM/912 (Av8r3400) 7. 03:50 PM - Re: S5 Trim and control forces (Tom Jones) 8. 04:44 PM - Re: Re: S5 Trim and control forces (Clint Bazzill) 9. 05:41 PM - Re: Re: RPM/912 (Clint Bazzill) 10. 09:44 PM - Re: RPM/912 (Av8r3400) 11. 11:04 PM - Re: S5 Trim and control forces (skyring) ________________________________ Message 1 _____________________________________ Time: 03:13:31 AM PST US Subject: Kitfox-List: S5 Trim and control forces From: "skyring" Our inspector is unhappy about the fact that in landing configuration i.e. 22 degree flaps and about 50 kts on our S5 Outback we still need some back pressure on the stick. That is, we can't trim out all of the nose down forces. My understanding is that this is normal on a Kitfox and there is no easy way (when fitted with the factory electric trim) to remove these forces. I can live with the very light back pressure required but he's clearly not happy. Is my assumption correct? Any comments appreciated. Kerry S5 912ULS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=344765#344765 ________________________________ Message 2 _____________________________________ Time: 03:29:07 AM PST US From: Lynn Matteson Subject: Re: Kitfox-List: S5 Trim and control forces My test pilot and (later on) flight instructor had me add about 2" of length to the elevator trim on my IV. This helped, he said, but after I got my instruction in the plane and got used to it, I found that 2" was too much and that it made the trim control too sensitive. I cut off about 1/4", then further fine-tuned the tab by increasing the length of the horn on the tab. This allowed the tab to move a shorter distance for each increment of the servo. Lynn Matteson Kitfox IV Speedster, taildragger Jabiru 2200, #2062 Temporarily w/Sensenich 55.5 x 46 prop while Prince prop (64 x 30, P-tip) is in for upgrade Electroair direct-fire ignition system Rotec TBI-40 injection (sleeved to 36mm) Status: flying with "Ramcharger" intake manifold...1127 hrs (since 3-27-2006) On Jul 3, 2011, at 6:10 AM, skyring wrote: > > > Our inspector is unhappy about the fact that in landing > configuration i.e. 22 degree flaps and about 50 kts on our S5 > Outback we still need some back pressure on the stick. That is, we > can't trim out all of the nose down forces. My understanding is > that this is normal on a Kitfox and there is no easy way (when > fitted with the factory electric trim) to remove these forces. I > can live with the very light back pressure required but he's > clearly not happy. Is my assumption correct? Any comments appreciated. > Kerry > S5 912ULS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=344765#344765 > > ________________________________ Message 3 _____________________________________ Time: 07:38:54 AM PST US From: "rtmarshall" Subject: Kitfox-List: RPM/912 Hello Kitfox flyers, For those of you who have the 912 and 3 Blade 68" GSC prop, Do you see more than 5K RPM or more on take off from field elevations of 5K, we typically see 8 to 9 K density alt days up here in the High Sierras. So from sea level we lose 5" Manifold pressure. Our kit fox is only able to turn 4500 Rpm static at 5 K field elevation and stays about the same on climb out, the prop pitch is 15 degrees. Any and all comments are welcome and we appreciate your input and replies. Thanks Bob and Toodie ________________________________ Message 4 _____________________________________ Time: 08:38:38 AM PST US Subject: Kitfox-List: Re: RPM/912 From: "Roger Lee" Hi Bob, You should set the prop pitch to achieve 5500-5550 rpm WOT flat and level at your normal cruise altitude. This will give you the best all a round performance for all flight characteristics. To much pitch like yours does equate to loss of climb, more fuel and higher engine temps. Too little pitch gives you good climb, but you loose cruise and fuel economy. Balance of all the flight characteristics is the key for normal flight operations. Don't get hung up on static it is just a starting point to getting things dialed in. You care more about WOT during flight. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center Home 520-574-1080 TRY HOME FIRST Cell 520-349-7056 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=344782#344782 ________________________________ Message 5 _____________________________________ Time: 11:34:56 AM PST US Subject: Re: Kitfox-List: S5 Trim and control forces From: Michael Gibbs Certified airplanes are required to have enough trim authority to hold approach speed without pilot intervention but, of course, your Kitfox is not a certified airplane. And yes, this is normal for Kitfoxes. Mike G. Phoenix, AZ Kitfox IV-1200 Speedster, Kitfox Series 6 (& 3/4!) On Jul 3, 2011, at 3:10 AM, "skyring" wrote: > > Our inspector is unhappy about the fact that in landing configuration i.e. 22 degree flaps and about 50 kts on our S5 Outback we still need some back pressure on the stick. That is, we can't trim out all of the nose down forces. My understanding is that this is normal on a Kitfox and there is no easy way (when fitted with the factory electric trim) to remove these forces. I can live with the very light back pressure required but he's clearly not happy. Is my assumption correct? Any comments appreciated. > Kerry > S5 912ULS > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=344765#344765 > > > > > > > > > > ________________________________ Message 6 _____________________________________ Time: 12:14:44 PM PST US Subject: Kitfox-List: Re: RPM/912 From: "Av8r3400" less than 5200 rpm with full throttle in a 912 leads to excessive cylinder pressure and could seriously damage your engine. FYI -------- Thanks, Av8r3400 Kitfox Model IV-1200 W/912UL & IVO Kitfox Model IV-1050 W/912UL & Warp Read this topic online here: http://forums.matronics.com/viewtopic.php?p=344799#344799 ________________________________ Message 7 _____________________________________ Time: 03:50:23 PM PST US Subject: Kitfox-List: Re: S5 Trim and control forces From: "Tom Jones" Kerry, am I correct in assuming you are not located in the US? The kitfox is a proven design. A big and important part of the kitfox design is the flaperons which produce a nose down pitch when deployed as flaps. Just throwing out some ideas. Do you have authority as the manufacturer of this plane to write in the operators manual that normal landings are made with zero flaps, or maybe a placard on the panel to deal with it. Your plane, with a 912 engine seems to be pretty much built by the book so I am also assuming its not a nose heavy condition that needs correcting? -------- Tom Jones Classic IV 503 Rotax, 72 inch Two blade Warp Ellensburg, WA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=344819#344819 ________________________________ Message 8 _____________________________________ Time: 04:44:50 PM PST US From: Clint Bazzill Subject: RE: Kitfox-List: Re: S5 Trim and control forces Kerry=2C I have a Model Iv-1200. I had the same problem when the flaperons were emp loyed. I flew for almost 500 hours before playing with flaps. I heard so many stories=2C all negative=2C I didn't go there. Here is my solution=2C first I put springs on push pull tube to elevator. That took the heavy weight off the elevator which will allow you to do more up trim. Then I put gap seal in place. Next I installed vortex generator s under stabilizer. Then I installed the larger elevator that is used on t he nose wheel Model IV. I now slow the airplane in the pattern to 80 MPH indicated. Apply the flap s=2C mostly full. Use full up trim. The airplane flys at 65 to 70 with ver y little pressure on stick. If you apply power=2C the nose will pitch up. Hope this helps. Clint 912ULS Model IV > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=344819#344819 > > > > > > > =========== =========== =========== =========== > > > ________________________________ Message 9 _____________________________________ Time: 05:41:51 PM PST US From: Clint Bazzill Subject: RE: Kitfox-List: Re: RPM/912 Not at5 5000 feet with a MP of 24 inches Clint > Subject: Kitfox-List: Re: RPM/912 > From: theav8rweb@yahoo.com > Date: Sun=2C 3 Jul 2011 12:12:13 -0700 > To: kitfox-list@matronics.com > > > less than 5200 rpm with full throttle in a 912 leads to excessive cylinde r pressure and could seriously damage your engine. > > FYI > > -------- > Thanks=2C > Av8r3400 > > Kitfox Model IV-1200 W/912UL &=3B IVO > Kitfox Model IV-1050 W/912UL &=3B Warp > > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=344799#344799 > > > > > > > =========== =========== =========== =========== > > > ________________________________ Message 10 ____________________________________ Time: 09:44:02 PM PST US Subject: Kitfox-List: Re: RPM/912 From: "Av8r3400" Altitude was never specified during the seminar that I got that information from. Pressure differential from inside the combustion chamber versus the ambient pressure surrounding the engine is where the damage would come from, IMO. -------- Thanks, Av8r3400 Kitfox Model IV-1200 W/912UL & IVO Kitfox Model IV-1050 W/912UL & Warp Read this topic online here: http://forums.matronics.com/viewtopic.php?p=344840#344840 ________________________________ Message 11 ____________________________________ Time: 11:04:26 PM PST US Subject: Kitfox-List: Re: S5 Trim and control forces From: "skyring" Thanks for all the replies and yes I am in Europe. The answers give me the reassurance I need that what we have is absolutely normal for a kitfox S5 with electric trim and the movable tail plane. Tom, yes we have built by the book and the inspector has indicated that a paragraph in the aircraft flight manual observing that in landing configuration with full flaps the aircraft will require some back-pressure on the stick could satisfy him. I would prefer this to one saying "no flaps" for landing as I think they are very useful at times. And a go-around with full flaps is also no problem with the S5. By the way the nose-down trim effect of the flaps was very useful when I had the trim stick in the full nose-up position (poor earth on switch) during testing. By using full flap and just enough power for 60 kts the control forces were quite manageable for a return to the field and problem free landing. So the plane meets the requirement for controls to overcome a runaway trim. Thanks again to the list. Kerry. 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