---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Thu 01/20/11: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:56 AM - Re: Re: Main wing bushings (GRAHAM SINGLETON) 2. 03:42 AM - Re: Re: Main wing bushings (Bob Harrison) 3. 07:31 PM - Re: Re: Main wing bushings (Bud Yerly) ________________________________ Message 1 _____________________________________ Time: 12:56:09 AM PST US From: GRAHAM SINGLETON Subject: Re: Europa-List: Re: Main wing bushings Kingsley=0AIvan didn't do the stress calcs. As I understand it, (I'm not a stress man =0Aeither) you could leave out the bushes in the seat back. =0A =0AThe motor glider has been redesigned and the spar tangs have been stiffe ned. I =0Adon't know if the seat back bushes were deleted. I just asked Iva n and he =0Adoesn't know either (or chose not to remember)=0AI guess Bud mi ght tell us?=0AGraham=0A=0A=0A=0A=0A________________________________=0AFrom : Kingsley Hurst =0ATo: europa-list@matronics.com =0ASent: Thursday, 20 January, 2011 3:33:19=0ASubject: Re: Europa-List: Re: Main wing bushings=0A=0A=EF=BB =0AHello Will,=0A =0AI am not suggestin g there is any alternative for us as builders. The design =0A"as is" obvi ously fits the bill so the old adage, "if it ain't broke, don't fix =0Ait" is appropriate.=0A =0AFrom a designer's point of view however, if you ins pect the various methods =0Aemployed by sailplane manufacturers, there are possibly better ways of doing =0Ait. I have never seen a sailplane with t he same set-up as the Europa but that =0Adoesn't mean there isn't any. Iv an Shaw did get some ideas from sailplanes so =0Amaybe he found one . . . . I dunno!=0A =0ACheers=0AKingsley=0A =0Ado not archive=0A =0A----- Origin al Message ----- =0A>From: William Daniell =0A>To: europa-list@matronics .com =0A>Sent: Wednesday, January 19, 2011 9:57 PM=0A>Subject: Re: Europ a-List: Re: Main wing bushings=0A>=0A>Kingsley=0A>I don't understand due to my limited knowledge of the engineering.=0A>What alternative might t =================== =0A ________________________________ Message 2 _____________________________________ Time: 03:42:40 AM PST US From: "Bob Harrison" Subject: RE: Europa-List: Re: Main wing bushings Hi! I understand that the late Barry Mellors did all the fuselage calcs. IMHO he was a brilliant engineer in all things aircraft and worked in his own self employed right doing lots of work for the Brazillian aircraft manufacturers Combine him with Don Dykins wing designer and you had the benefit of a wonderful combine. Unfortunately we obviously can=99t speak to Barry anymore to discuss the items you are interested in. However it may help you to understand that when the wing fails it fails forward. Like has been suggested =9Cif it ain=99t broke don=99t try to fix it !=9D Barry, bless him, helped immensely with the engine mount design and PFA approval for the Jabiru 3300 engine mount and I=99m quite sure the aircraft would never have flown without his design skill and approach to the intransigence of the PFA engineer of the time! Regards To all Bob Harrison G-PTAG From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Kingsley Hurst Sent: 20 January 2011 03:33 Subject: Re: Europa-List: Re: Main wing bushings Hello Will, I am not suggesting there is any alternative for us as builders. The design "as is" obviously fits the bill so the old adage, "if it ain't broke, don't fix it" is appropriate. >From a designer's point of view however, if you inspect the various methods employed by sailplane manufacturers, there are possibly better ways of doing it. I have never seen a sailplane with the same set-up as the Europa but that doesn't mean there isn't any. Ivan Shaw did get some ideas from sailplanes so maybe he found one . . . . I dunno! Cheers Kingsley do not archive ----- Original Message ----- From: William Daniell Sent: Wednesday, January 19, 2011 9:57 PM Subject: Re: Europa-List: Re: Main wing bushings Kingsley I don't understand due to my limited knowledge of the engineering. What alternative might there be? Will ________________________________ Message 3 _____________________________________ Time: 07:31:22 PM PST US From: "Bud Yerly" Subject: Re: Europa-List: Re: Main wing bushings Sorry guys if I don't understand the actual question about the bushes and bearing loads! I had to go back and try to picture the question, in the mean time, Grahams analysis is spot on as usual. To visualize the loads read on to my miscellaneous drivel. The two spars are basically a set of scissors.. The pins lock the spars together like a pair of scissors trying to cut a steel bar. The pins of course must go through the fuselage and each spar to hold the fuselage gravity forces and translate the lift forces of the wings to the fuselage. The bushes distribute the load and the hardened pins take the lifting loads as shear load. Essentially the fuselage (about 1100 lbs. loaded with down tail forces added under G and acceleration as well as the radial Gs) hangs from the pins. The spars bend under the vertical load. Like a pair of scissors, that is trying to cut through that solid steel bar stock, so picture the force of your hands causing the thin blades to bend, as you would expect a thin long pair of scissors to twist, bending vertical and laterally. Mod 52s rear socket and tube takes the forward element of the lift vector (the lift of the wing near maximum is forward and up, really pulling on the aft socket) and translates the load through root rib, to the rear attach to the steel tube in fuselage which is under tension but does not significantly contribute to the vertical lift load. Because the aircraft is fiberglass and it does move a bit under load, the spars twist some under load. The Mod 52s, 1/2 inch spar pip pin, keeps the tip of the starboard spar in check and from slipping into the control linkage under bending and twisting. The spar strap deters twist and spar separation under load from their at rest positions. The pins hardened strength allows it to not be sheared by the huge shearing action of the two spars against the fuselage and each other. So why doesn't the spar pin bend at the bush? Picture the fuselage weight is pulling down at the left cockpit bush, the left spar (forward) is pulling up, but the right spar (aft) is pushing down, and the sum of the actions basically keeps the pin horizontal. All that force though is on only one 1/2 inch in diameter pin, and that is one heck of a lot of shearing force. Because it is over a short distance (and our spars are tight together), we don't have to have microns of tolerance in the pin to bushing fit.....The action of the spars against one another brilliantly keeps the pin horizontal and not from bending upward at the fuselage bush and slipping off the pins as one would expect at first glance thinking of only one spar. It is a clean neat simple design. Could it be better, you bet, but can it be built by us simple beings easily and cost effective? Probably not, so do I want to change it? No way, it isn't worth it. Like you all say, it ain't broke, so don't fix it. For you new builders, keep your bushes and spars at a reasonable tightness and you will be fine. If you must ream the bush a bit because the port pin is too tight, you only need to ream a couple of thousandths normally. A heated pin through the bushes works best, as Graham said before, to take a slightly out of align bush and right it. Don't panic at the fuselage bush slop as the spars keep the pin horizontal. Always use the spar strap and the pip pin adjusted as per the manual with the washer to distribute the load on the poor spar cup. Don't substitute bolts for the wing pins provided unless properly hardened. If you own a classic, do a Mod 52/74 as it is great insurance. Regards to all and I hope to see you at Sun "n Fun. Bud Yerly Custom Flight Creations, Inc. www.customflightcreations.com (813) 653-4989 ----- Original Message ----- From: Bob Harrison To: europa-list@matronics.com Sent: Thursday, January 20, 2011 6:38 AM Subject: RE: Europa-List: Re: Main wing bushings Hi! I understand that the late Barry Mellors did all the fuselage calcs. IMHO he was a brilliant engineer in all things aircraft and worked in his own self employed right doing lots of work for the Brazillian aircraft manufacturers Combine him with Don Dykins wing designer and you had the benefit of a wonderful combine. Unfortunately we obviously can=99t speak to Barry anymore to discuss the items you are interested in. However it may help you to understand that when the wing fails it fails forward. Like has been suggested =9Cif it ain=99t broke don=99t try to fix it !=9D Barry, bless him, helped immensely with the engine mount design and PFA approval for the Jabiru 3300 engine mount and I=99m quite sure the aircraft would never have flown without his design skill and approach to the intransigence of the PFA engineer of the time! Regards To all Bob Harrison G-PTAG From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Kingsley Hurst Sent: 20 January 2011 03:33 To: europa-list@matronics.com Subject: Re: Europa-List: Re: Main wing bushings Hello Will, I am not suggesting there is any alternative for us as builders. The design "as is" obviously fits the bill so the old adage, "if it ain't broke, don't fix it" is appropriate. From a designer's point of view however, if you inspect the various methods employed by sailplane manufacturers, there are possibly better ways of doing it. I have never seen a sailplane with the same set-up as the Europa but that doesn't mean there isn't any. Ivan Shaw did get some ideas from sailplanes so maybe he found one . . . . I dunno! Cheers Kingsley do not archive ----- Original Message ----- From: William Daniell To: europa-list@matronics.com Sent: Wednesday, January 19, 2011 9:57 PM Subject: Re: Europa-List: Re: Main wing bushings Kingsley I don't understand due to my limited knowledge of the engineering. What alternative might there be? 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