---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Thu 03/04/21: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:41 AM - Re: Re: Stall warning airspeed for XS Mono (Bud Yerly) ________________________________ Message 1 _____________________________________ Time: 07:41:03 AM PST US From: Bud Yerly Subject: RE: Europa-List: Re: Stall warning airspeed for XS Mono Ron, I=92m home from more medical tests today so here goes. The pre-stall warning will be close gear up/down on the mono. That is flap up/down also in a trigear. Different, but close enough. Not to be disrespectful, but an easy reference is The Theory of Wing Sectio ns and note how the pitch and stall angle change with a plane flap. Fowler flap references are less available as they are company proprietary data. Or for the hands-on guy, go get proficient in the C-172 and set the flaps t o just shy of 30 and note how the stall indicator horn (using the same suct ion device for a stall warning flap up and down) behaves. The clean stall warning is remarkably close to the pre-stall warning at low flap angles between 0-30 at slow speed approaches to the stall. At 40 deg rees there is less of a warning as speed bleeds rapidly, but there is still ample warning. Note: Approach to stall testing is at a slow rate of 1 knot per second. Rapid changes in AoA or rapid decrease of airspeed approaching the stall wi ll affect different aircraft from plane to plane due to design differences and rigging as well as the stall indicators design. Pilot control and tech nique also affect the stall. We all are =93ham fists=94 on initial flights in a new aircraft until we get proficient. I hope I don=92t sound flippant, but It is like one of my commanders quipp ed "you're measuring it with a micrometer, marking it with a crayon and the n cutting it with an ax". Obsessing with small details can make you miss t he main point which is build the aircraft per the manual. However, learnin g should never stop, and asking questions is good, but questioning the desi gn can lead you, me and others into making changes and decisions that perha ps are not well thought out or even applicable. Build and rig the plane correctly IAW the manual, then set the add on stall indicators or devices of your choice like the book says and then test. Fl y IAW the handbook at the speeds prescribed and the aircraft will return ho nest feedback. Expand the flight envelope slowly. Don=92t get into the we eds on the detail of add on systems or try to redesign things unless you pe rsonally have calculated, and tested your change. For instance: The Europ a POH is very good provided it is read and followed. Don't just put stall strips on and paint over them and expect the pre-stall warning to be what y ou desire. Tape them on, and test. Take baby steps and test three mistake s high. Then get close to the ground. Use caution and a long runway to de termine how these devices work near the runway pre-touchdown. Then reposit ion and test again until the warning is acceptable to you. Some add on sta ll strips, AoA indicators, speed warners, and lift reserve indicators and others find omitting the stall strips and such devices is perfectly fine fo r them and their style of flying. The latter feel these warning horns and lights on a straight wing airplane are just annoying bells and whistles. A mateur Experimental Aviation is a diverse group. (ATTENTION: for the sensi tive of feelings, please disregard the following comment.) Frankly I was o ne of the latter but to sell the aircraft I am now adding these =93bells an d whistles=94 as the civilian market in used experimental aircraft seems to need these. I am appalled that many of the second hand owners buy before they have even flown the aircraft and other than the prestart checklist, ha ve no idea what=92s in the POH or why. If a wing drops in a stall they fea r the stall or label the aircraft is a killer, rather than noting they fail ed to keep the ball centered i.e. coordinated flight into the stall. (ATTE NTION: Resume reading for the sensitive pilot.) As far as stall speeds and loading, I hope to be more clear here to you per sonally. Because many folks arbitrarily decided a higher gross weight was necessary using the super-factor built into the Europa design (because they didn=92t control their empty weight), I didn=92t load my plane beyond the 1370 gross in the test phase. Hell my ID placard says 1300 still for the C lassic, but the ops manuals (POH for my aircraft) have changed since Mod 52 and my MTOW change. Although a 1450 GW increase was the rage here in the US 20 years ago, I completed my initial flight testing below 1370 after Mod 52. I worked up to 1450 MTOW (max takeoff weight) and kept the CG well wi thin the limits. I personally disassembled my aircraft and inspected the a ircraft lift points and attachments after each test session. Same with my clients. I do not land above 1370 pounds without a post flight inspection (over gross/hard landing checklist), as I did not drop test the aircraft t o determine gear stresses at 1450 pounds. I personally only use 1450 as a MTOW in smooth air and hard surfaced runways. My CG range was modified aft er testing and my maximum G limits lowered proportionally also. My Operati ons Limits in my aircrafts flight manual are written for my airplane and it is flown by those operational limits I have tested. Abrupt flight maneuve rs and turbulence were and are still avoided when flying operationally abov e 1370 lbs. Although the Europa was built with a super-factor to allow for amateur building, it is still a kit aircraft, with hand molded components for the most part and there are variations we cannot predict. What we know for everyone is: fly the plane IAW the manual and it will behave. Redesig ning or "stretching" the limits should be avoided for the novice builder. Not all modifications attempted by others will work exactly the same on you r aircraft. There is always some tweaking. I try to write up my testing e valuations or changes and provide my documentation and test results, but th at doesn=92t mean it is going to work for you. Test and evaluate, then tes t some more. (Frankly, that is all I ever seem to do rather than long enjo yable cross countries as many use their aircraft for.) Some governments around the world limit ANY change to the design or modific ation of any aircraft without government approval. This may be nanny state to some, but it occurs here in the US also. Case in point is the LSA mark et. Even in the US the light sport ELSA is not really an experimental airc raft. By regulation, its assembly cannot deviate from the factory built SL SA without approval from the manufacturer or by contacting the FAA inspecto r and changing its registration and airworthiness to EXPERIMENTAL EXHIBITIO N CLASS. As many of these =93ELSA kits=94 are a less than 51% kits, the bu ilder cannot be issued a repairman=92s certificate for these aircraft they have built, yet they are considered Experimental Amateur Built by the FAA b ut, are still ELSA kits and are relegated to exhibition class. It is a r egulatory mess now as some DARs and FAA inspectors are ignorant of the actu al wording in the regulation and intent. Now that accident information is being evaluated closer, we shall see how it is handled or if it stays a vag ue regulatory mess. Probably clear as mud. Bud Yerly Best Regards, Bud Yerly -----Original Message----- From: owner-europa-list-server@matronics.com On Behalf Of rparigoris Sent: Thursday, March 04, 2021 2:23 AM Subject: Europa-List: Re: Stall warning airspeed for XS Mono o:rparigor@hotmail.com>> Hi Bud Thanks for reply. Curious, if you were to set stall warning 5 knots above stall with flaps and gear down on a Mono XS, when approx. might you g et warning above (perhaps below?) stall with gear and flaps up? Ron P. Read this topic online here: https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fforums.ma tronics.com%2Fviewtopic.php%3Fp%3D500855%23500855&data=04%7C01%7C%7C8 da3b3a3668147b23d9508d8dedef932%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0% 7C637504396541698113%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2 luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=dSELxgxvkIOPTu00NZv 7vOx9H3NXoXXTmvzgowaE470%3D&reserved=0 %2Fwww.matronics.com%2FNavigator%3FEuropa-List&data=04%7C01%7C%7C8da3 b3a3668147b23d9508d8dedef932%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C6 37504396541708104%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luM zIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Jksi0K9dg3K9WjtnNdvRhh l2%2BiVHgkheyKk8KUmhTGI%3D&reserved=0 %2Fforums.matronics.com%2F&data=04%7C01%7C%7C8da3b3a3668147b23d9508d8 dedef932%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637504396541708104%7C Unknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiL CJXVCI6Mn0%3D%7C1000&sdata=V0yUPprBAOWnlELXcizpTQ%2F6tZqdpw6gVQF%2BxF S194k%3D&reserved=0 %2Fwiki.matronics.com%2F&data=04%7C01%7C%7C8da3b3a3668147b23d9508d8de def932%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637504396541708104%7CUn known%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJ XVCI6Mn0%3D%7C1000&sdata=V1uaJCH%2BtUNaIrLhK8TS1g%2BwOdRl%2FAxS9d%2BR RkWe5aw%3D&reserved=0 %2Fwww.matronics.com%2Fcontribution&data=04%7C01%7C%7C8da3b3a3668147b 23d9508d8dedef932%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637504396541 708104%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6 Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=epyoxdXR4X7ZzbprQoEpjY8zI%2BH4EtN 1kEcGFYTb0xk%3D&reserved=0 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-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/europa-list Browse Digests http://www.matronics.com/digest/europa-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.