Europa-List Digest Archive

Sun 08/19/12


Total Messages Posted: 12



Today's Message Index:
----------------------
 
     1. 01:44 AM - Re: LAA Rally (Alasdair Milne)
     2. 04:40 AM - Re: LAA Rally (RCC Sky Mail)
     3. 06:46 AM - Wheel fairings (Frans Veldman)
     4. 07:12 AM - Re: Wheel fairings (Fred Klein)
     5. 07:32 AM - Re: rotax 912S grounding strap position (PHILLIPS I)
     6. 07:32 AM - Re: Mod 77 (Frans Veldman)
     7. 07:52 AM - Master Brake Cylinder Mono (Jerry Rehn)
     8. 10:02 AM - Landing mishap - asking for advise (zwakie)
     9. 10:58 AM - Re: Landing mishap - asking for advise (David Joyce)
    10. 01:42 PM - Re: Wheel fairings (craig)
    11. 03:15 PM - Re: [Spam] Wheel fairings (Alex Kaarsberg)
    12. 03:38 PM - Re: Wheel fairings (Frans Veldman)
 
 
 


Message 1


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    Time: 01:44:04 AM PST US
    From: "Alasdair Milne" <milneab@btinternet.com>
    Subject: Re: LAA Rally
    Dear Steve, I intend to be at Sywell on Friday and Saturday. Slot bookings are 9.30 and 9. 00 so You can fit me in for 2- 2 hour slots on both days. I see Swift has unveiled the new thing so I expect we will be overshadowed. I am at present grounded with a radiator (coolant) leak and have spent last week trying to find out from Karen the delivery of a replacement, without success. Do you know anyone with a Firewall Forward kit from which I could borrow the radiator, to be replaced by a new one when delivered? Yours, Alasdair -----Original Message----- From: Steven Pitt Sent: Wednesday, August 15, 2012 2:12 PM Subject: Europa-List: LAA Rally To all those members intending to visit the LAA Rally at Sywell on the 31st August to 2nd September. Can you spare a couple of hours to help man a stand? The Club has been tasked to man two stands at the Rally and thanks to Alan Twigg he will have his glider fuselage in the LAA Tent area. The second stand will be part of the Europa/Swift stand in the main commercial area. The Club will have its own marquee alongside the Caravan of Swift and there will be the cockpit module and David Stanbridge's demonstrator which is in course of production. Whilst I have a core of volunteers for the three days it would be appreciated if anyone could volunteer for either stand for a couple of hours. Please contact me direct on steven.pitt2@ntlworld.com. Thanks Steve Pitt Chairman, Europa Club


    Message 2


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    Time: 04:40:30 AM PST US
    Subject: Re: LAA Rally
    From: RCC Sky Mail <richard.churchill-coleman@sky.com>
    Alasdair I have one for a 912s ff kit. Richard C-C 07977 454421 On 19 Aug 2012, at 09:41, "Alasdair Milne" <milneab@btinternet.com> wrote: > > Dear Steve, > > I intend to be at Sywell on Friday and Saturday. Slot bookings are 9.30 and 9. 00 so You can fit me in for 2- 2 hour slots on both days. > > I see Swift has unveiled the new thing so I expect we will be overshadowed. > > I am at present grounded with a radiator (coolant) leak and have spent last week trying to find out from Karen the delivery of a replacement, without success. Do you know anyone with a Firewall Forward kit from which I could borrow the radiator, to be replaced by a new one when delivered? > > Yours, > > Alasdair > > -----Original Message----- From: Steven Pitt > Sent: Wednesday, August 15, 2012 2:12 PM > To: europa-list@matronics.com > Subject: Europa-List: LAA Rally > > > To all those members intending to visit the LAA Rally at Sywell on the 31st > August to 2nd September. > Can you spare a couple of hours to help man a stand? > The Club has been tasked to man two stands at the Rally and thanks to Alan > Twigg he will have his glider fuselage in the LAA Tent area. > The second stand will be part of the Europa/Swift stand in the main > commercial area. The Club will have its own marquee alongside the Caravan of > Swift and there will be the cockpit module and David Stanbridge's > demonstrator which is in course of production. > Whilst I have a core of volunteers for the three days it would be > appreciated if anyone could volunteer for either stand for a couple of > hours. > Please contact me direct on steven.pitt2@ntlworld.com. > Thanks > Steve Pitt > Chairman, Europa Club > > > > > > > > > >


    Message 3


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    Time: 06:46:49 AM PST US
    From: Frans Veldman <frans@privatepilots.nl>
    Subject: Wheel fairings
    On 08/12/2012 07:24 PM, Bud Yerly wrote: > Frans, > I'll look for some pictures. I don't have them at the home office today. The reason I was asking is that I'm in the process of making some improved wheel fairings. It would be nice to share some ideas to the benefit of all of us, which is the purpose of this forum. Well, I have some ideas to share. I started with the nose wheel fairing because there is only one of it so I only have to make one test sample, and I disliked the original nose wheel fairing more than the main wheel fairings. To improve on something, one first has to identify the shortcomings. For me, the shortcomings of the original fairing are: 1) Poor fit. We all experienced that the thing was impossible to get symmetric. (I have been told that the company now corrected this error but that didn't solve my problem with the already bought fairing). 2) It is wider than necessary. Apart from the obvious aerodynamic disadvantage, the extra width also implies that the fairing has to bend in sharply at the underside to meet up with the smaller wheel. This bend further creates interference drag, and it increases vulnerability to objects on the ground. Ideally, the fairing's bottom should not be wider than the track of the wheel. 3) Too weak. Partly as a result of the width, but also due to the material itself. 4) The vertical division into two halves. These halves do not match well together, they meet at an angle and often bulge out, disrupting the airflow up front and negating the main purpose of the rest of the fairing behind it. 5) The clutter caused by all the fasteners, all on a separate height. Add a hole at the axle for a tow bar, and there are 5 levels (on each side!) where the airflow gets disrupted. 6) Too small in height. I would like to hide more of the wheel, and I also would like to fair in my 3cm shaft extension. (This mod was necessary to allow a larger diameter prop and still maintain enough ground clearance). 7) Too short. The length might be theoretically right, but if the fairing is not aligned perfectly with the airflow it should be longer to allow a shallow decline of the "downwind" side of the fairing to keep the airflow attached. And the fairing is likely not aligned perfectly, due to the proximity of the prop, and it is also quite possible that during take off the nose wheel turns a bit to a side while leaving the ground, especially while taking of in a cross wind. How did I improve on all this? 1) A key decision was to make the fairing from aramide (kevlar) instead of glass. Aramide has less tensile strength than glass or carbon, but it won't crack and it is highly resistant to impact forces. If it is literally(!) bullet proof, it should also cope well with rocks and bumps. The downside is that the material is hard to handle, you can forget about using normal scissors and knifes. We made part of a test fairing with two layups of aramide and had great fun trying to destroy it once it was cured. We jumped on it so it pancaked, but it just popped back into shape after we left it, without any damage. We actually folded it, the epoxy itself cracked a bit but not a single strand broke and it folded right back into its original shape (but of course this time with a visible fold line). If I were living in the US I would probably also have fired some bullets at it just for laughs. This material allowed me to make a much deeper fairing and still don't have to worry about soft fields and hitting some rocks, while keeping the weight low at the same time. On the final fairing we tested it by taking the wheel off the ground, putting obstacles below the fairing and putting the aircraft on its own weight again, so that the entire weight of the aircraft was resting on the fairing. No problem. It will probably survive a flat tire with only some paint damage. We could probably land on it without any wheel inside at all. 2) A decision was made to keep the axle nuts outside of the fairing. We needed an attach point for the tow bar anyway, and it would either be a hole or a small protrusion. By keeping the axle ends outside of the fairing I could make the fairing more than 5 cm (2 inches) smaller! Also, I could eliminate the arms (saving additional width and weight) and fasteners (leaving the rest of the fairing smooth), by just embedding two metal plates in the layups and using the axle bolts itself to fasten the fairing. Now the fairing got significantly smaller, also the theoretical length would be smaller. Because I wanted a longer fairing, I just kept the length of the original fairing to get the ratio I wanted. And because the fairing is so small, it is easy to make a natural transition into the wheel at the bottom of the fairing without any curve or flat part on the sides of the underside. 3) Instead of the vertical division, I wanted a lengthwise division so the cut would be in line with the airflow. Instead of dividing it into two halves, Ilona came up with the idea to make a cut so that a part of the bottom can be taken off. This allows the wheel to enter, and it makes the vulnerable bottom part to be easily replaceable. Also, it gives the interesting option to fly with the bottom removed in winter time, to give more clearance for the wheel and to allow mud and snow to fall out by itself. A few notes: The upper part of the fairing is wider than the lower part. This is because the upper part must also encapsulate the yoke. If then a straight angle to the rear is followed, the rear of the fairing automatically gets this "swept back" appearance and its curved underside. This is also the reason that the "nose" is above the center of the wheel. Of course the bottom of the fairing is a bit of a compromise to get enough clearance on ramps and to blend in the profile of the wheel as good as possible. The "skirts" on the side are purposedly not rigid. They will give way if something catches between the tire and the skirt. I made the shape of blue foam, and decided to leave it inside except of course for the cavity of the wheel. This adds further strength for a very low weight penalty. There is a small "bulge" in the division cut on the port side, this is to facilitate access to the valve of the tire. I only have to drop the underside of the fairing to get access to it. To remove the entire fairing, the wheel assembly must be taken off. There is however not much need to remove the fairing, as even the wheel can be taken out of the yoke without removing the upper part of the fairing. The fairing is reinforced near the shaft. This forms the third attachment point, so that the fairing can not rotate over the axle. There is additional clearance at the rear of the tire, so the wheel can never "catch" the fairing. The yellow appearance of the fairing is due to the color of the aramide cloth. The ragged appearance of edges is also due to the aramide. Of course the fairing will receive a proper finish. This is a one of design, however if someone wants to use it as a plug that is possible. Keep in mind though that it is designed for nose wheel assemblies with a 3cm longer shaft than original. Frans


    Message 4


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    Time: 07:12:51 AM PST US
    From: Fred Klein <fklein@orcasonline.com>
    Subject: Re: Wheel fairings
    On Aug 19, 2012, at 6:45 AM, Frans Veldman wrote: > The reason I was asking is that I'm in the process of making some > improved wheel fairings. It would be nice to share some ideas to the > benefit of all of us, which is the purpose of this forum. > > Well, I have some ideas to share. Frans... I tip my hat to you and IIona...I salute your analysis, design, and execution...very nice work! Fred


    Message 5


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    Time: 07:32:21 AM PST US
    Subject: Re: rotax 912S grounding strap position
    From: PHILLIPS I <ivor.phillips@ntlworld.com>
    In the middle of the engine right where the vacuum pump goes are two tapped holes used for a engine lift, They are a good size for earthing, i also fitted a smaller lead to the starter motor bolt, A bit of belts and bracer's but a good earth is paramount to reduce false warnings from sensors IMHO regards ivor On 18 August 2012 21:50, Jeff B <topglock@cox.net> wrote: > > Rowland, > > I typically ground directly to the exhaust pipe... > > Jeff - Baby Blue > > > On 8/18/2012 1:32 PM, Rowland Carson wrote: > >> rowlandcarson@gmail.com> >> >> I'm checking through the sizes of terminals that I'll need for various >> connexions. I cannot find in either the Rotax engine manual or the Europa >> FWF manual any identification of the point on the engine block that should >> be used for the electrical ground point. >> >> Is there any existing bolt or nut to which a grounding strap is typically >> connected? Or is there an empty tapped hole provided into which a screw can >> be fitted to retain a grounding strap? >> >> in friendship >> >> Rowland >> >> | Rowland Carson ... that's Rowland with a 'w' ... >> | <rowlandcarson@gmail.com> http://www.rowlandcarson.org.**uk<http://www.rowlandcarson.org.uk> >> | Skype, Twitter: rowland_carson Facebook: Rowland Carson >> | pictures: http://picasaweb.google.com/**rowlandcarson<http://picasaweb.google.com/rowlandcarson> >> >> >> >> >> >> >> >> > >


    Message 6


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    Time: 07:32:21 AM PST US
    From: Frans Veldman <frans@privatepilots.nl>
    Subject: Re: Mod 77
    Ian, On 08/11/2012 10:52 AM, G-IANI wrote: > How about an article for the Europa Flyer? It would be nice to know how you > achieved the near impossible ("I can see it, I can touch it, but not at the > same time") installation of the bell-crank assembly in a completed aircraft. That would not be too much trouble, but I didn't make any pictures of the installation. > If it seems possible for normal mortals (not Dutch) I can add it to the > instructions. One very important thing: I had already installed a vent opening in the sternpost to receive a 2" scat hose connected to the cabin. I made this connector removable with 3 anchor nuts in the flange. This 2" opening in the sternpost appeared to be handy for many things; if I ever wanted to take the elevator push rod out I could do it via this opening, but it is also handy for visual inspection of the tunnel from the rear of the ship, it just adds another angle to look at things. Now it came in handy for installation of mod 77. For the most part I could use it as a peek hole while working through the standard hatch, and I also used it to get a flexible drill extension in to drill the required holes. Because I think it is impossible to do mod 77 without such an opening in the sternpost I would propose to create this opening first. You could install it at the approximate height where the push rod for the rudder will pass through, and later put a cover on the opening with a hole in it for the push rod. This way it is also much easier to determine where exactly the opening for the push rod should be. And if you are not happy with the result you just make a new cover; instead if you have to make the hole in the sternpost you only have one shot at it and it will likely end up larger than necessary. > The parts list, on pages 1& 2, should be correct so please let me know if > you have spotted any errors. The confusion was mainly on part of the rivets. Not only in the docs but I also received a confusing set of rivets, including the dreaded AN470-AD4-10's. I also received too many cotter pins, too many cable ends, 4 very long AN525 bolts for no purpose. Oh and there is no mention in the document about the connection of the rudder end of the push rod. I received an EUR001 safety washer for it, the manual says to attach it similar as the other end, but as the rudder end has two lips instead of one the eye-bolt can't go anywhere anyway. I just put some AN416L washers on both ends between the lips. I would also like to see a different way to attach the push rod to the rudder, as it is very difficult to tighten the nut on the AN4-bolt via the rudder gap. Maybe just a bolt with a cotter pin through it would do? Anyway, you can't access it with a normal socket, and with a spanner the clearance is not enough to make a sufficient turn. I ended up using two ratcheting spanners but just one "click" is all I can get, so it takes hours to tighten the nut. (And no, you can't connect the push rod to the rudder first, as there is no way you can handle two spanners through the hatch to tighten the other end afterwards (I can get only one hand in it at the same time). Now I think of it: Maybe an anchor nut on that metal plate would make things easier, instead of the nut and bolt. Oh, and I discovered that the push rod is just as heavy as the rest of the assembly. Is there a reason why this is from steel instead of aluminium? We used aluminium for all the other controls in the ship (it looks like the aileron push rod is the same diameter but then in aluminium), so why has this one to be from heavy steel? > I have already added a reference to refinishing the base of the rudder to > the latest revision. Great! Frans


    Message 7


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    Time: 07:52:32 AM PST US
    Subject: Master Brake Cylinder Mono
    From: Jerry Rehn <rehn@rockisland.com>
    Hi all I am in need of the rubber parts for a rebuild or maybe the entire master cylinder if there is one out there discarded from a mono/tri conversion. Or source for parts? Thanks for help. Jerry Mono XS 914 Sent from my iPad


    Message 8


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    Time: 10:02:52 AM PST US
    Subject: Landing mishap - asking for advise
    From: "zwakie" <mz@cariama.nl>
    Last Monday I had a landing mishap on Texel (EHTX), resulting in a nose wheel collapse after a bounced landing.. Before asking my questions, I would like to express my BIG THANKS to Frans and Illona who drove their trailer up to Texel and drove PH-MZW back by road and ferry boat to my home base. Frans and Illona, words will always fall short when describing our gratitude! Also may thanks to Tim who phoned me up offering any help I would need! First examinations showed that propeller and nose gear leg are beyond repair. Lower cowling got some minor cracks. After I removed the cowling and the covering plate of the cockpit tunnel, I found another piece of damage: evidently the nose leg had rotated appr. 45 degrees in the nose gear leg tube, which resulted in the bump stop having pierced more or less sideways through the tunnel appr. 1" into the passenger foot well (see attached image). My questions to the forum: (1) How much structural strength does the pierced part of the tunnel take, and what procedure do you recommend for the repair? (2) I am planning to have a complete new nose gear leg assembly installed. Unknown at this moment is how to check the integrity of the landing gear frame. All suggestions are welcome! (3) Of course I will have a professional Rotax maintenance company perform shock load checks on the gearbox and the 912UL (80HP) engine. I think I have once read somewhere on the forum that no matter the outcome of the shock load checks, the crank bearings must be replaced. I could however not find any reference to this in the Rotax manuals. What is your idea on this? (4) What other engine checks should be performed? Anything else you would recommend doing/checking? (5) For a new propeller I am investigating a change from Arplast PV50 to Woodcomp SR3000/2W or SR3000/3. - Will any of these Woodcomps bring significantly improved performance compared to the Arplast? - Will it make any sense to opt for a high-twist Woodcomp and will these high-twist versions be a good fit for the small 80HP 912UL? Please be aware that changing propeller-type will force me having to go through a lengthy and costly procedure to obtain a new noise certificate from the Dutch CAA. Therefore I already decided to stick with Arplast PV50 unless a significant performance increase can be achieved. My question is a mere attempt to get a feel for what to expect... (6) Anything I missed above that needs looking at? Thanks very much for your advise! -------- Marcel (Europa Classic Tri-Gear PH-MZW) Read this topic online here: http://forums.matronics.com/viewtopic.php?p=381254#381254 Attachments: http://forums.matronics.com//files/foto1_193.jpg


    Message 9


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    Time: 10:58:02 AM PST US
    From: "David Joyce" <davidjoyce@doctors.org.uk>
    Subject: Re: Landing mishap - asking for advise
    Marcel, From recent experience I can give answers to some but not all of your questions: 3) & 4) There are set Rotax protocols for this. I believe it is advised to check the run out on the propeller shaft and the integrity of the gear system and if these are OK nothing else is needed , but if not the gear box comes off and you check the run out on the crank shaft and if that is out of tolerance you need a new crank shaft. In any case a proper Rotax authorised technician should be able to tell you exactly what is needed. 5) A Woodcomp high twist Sr30003W had significant benefits for me when I changed from a low twist SR2000. It added 4kt to max speed and improved fuel economy and made a major difference to cooling which had always been something of a problem for me. I guess a SR30002W would have enough clout to deal with your 912 but you could confirm that with Woodcomp. I will send you seperately a copy of the article I wrote with formal comparisons between my SR2000 and theSR3000W. Regards, David Joyce, G-XSDJ On Sun, 19 Aug 2012 10:01:54 -0700 "zwakie" <mz@cariama.nl> wrote: ><mz@cariama.nl> > > Last Monday I had a landing mishap on Texel (EHTX), >resulting in a nose wheel collapse after a bounced >landing.. > > Before asking my questions, I would like to express my >BIG THANKS to Frans and Illona who drove their trailer up >to Texel and drove PH-MZW back by road and ferry boat to >my home base. Frans and Illona, words will always fall >short when describing our gratitude! Also may thanks to >Tim who phoned me up offering any help I would need! > >First examinations showed that propeller and nose gear >leg are beyond repair. Lower cowling got some minor >cracks. After I removed the cowling and the covering >plate of the cockpit tunnel, I found another piece of >damage: evidently the nose leg had rotated appr. 45 >degrees in the nose gear leg tube, which resulted in the >bump stop having pierced more or less sideways through >the tunnel appr. 1" into the passenger foot well (see >attached image). > > My questions to the forum: > > (1) How much structural strength does the pierced part >of the tunnel take, and what procedure do you recommend >for the repair? > > (2) I am planning to have a complete new nose gear leg >assembly installed. Unknown at this moment is how to >check the integrity of the landing gear frame. All >suggestions are welcome! > > (3) Of course I will have a professional Rotax >maintenance company perform shock load checks on the >gearbox and the 912UL (80HP) engine. > I think I have once read somewhere on the forum that no >matter the outcome of the shock load checks, the crank >bearings must be replaced. I could however not find any >reference to this in the Rotax manuals. What is your idea >on this? > > (4) What other engine checks should be performed? >Anything else you would recommend doing/checking? > > (5) For a new propeller I am investigating a change from >Arplast PV50 to Woodcomp SR3000/2W or SR3000/3. > - Will any of these Woodcomps bring significantly >improved performance compared to the Arplast? > - Will it make any sense to opt for a high-twist >Woodcomp and will these high-twist versions be a good fit >for the small 80HP 912UL? > > Please be aware that changing propeller-type will force >me having to go through a lengthy and costly procedure to >obtain a new noise certificate from the Dutch CAA. >Therefore I already decided to stick with Arplast PV50 >unless a significant performance increase can be >achieved. My question is a mere attempt to get a feel for >what to expect... > > (6) Anything I missed above that needs looking at? > > Thanks very much for your advise! > > -------- > Marcel > (Europa Classic Tri-Gear PH-MZW) > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=381254#381254 > > > > > Attachments: > > http://forums.matronics.com//files/foto1_193.jpg > > > > >Un/Subscription, >Forums! >Admin. > > >


    Message 10


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    Time: 01:42:48 PM PST US
    From: "craig" <craigb@onthenet.com.au>
    Subject: Wheel fairings
    Frans, could you elaborate on the "correct length would be shorter" wouldn't the longer shallower transition Create less drag and thus make your longer fairing more efficient. Regards craig


    Message 11


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    Time: 03:15:56 PM PST US
    Subject: Re: Wheel fairings
    From: Alex Kaarsberg <kaarsberg@terra.com.br>
    Frans, Looks nice, what if you get a flat tire, any risk it may keep the wheel from turning? Not sure if that would make a difference or not.....just thinking aloud. Brds, Alex kit529 Enviado via iPhone Em 19/08/2012, s 10:45, Frans Veldman <frans@privatepilots.nl> escreveu: > On 08/12/2012 07:24 PM, Bud Yerly wrote: >> Frans, >> I'll look for some pictures. I don't have them at the home office today. > > The reason I was asking is that I'm in the process of making some improved wheel fairings. It would be nice to share some ideas to the benefit of all of us, which is the purpose of this forum. > > Well, I have some ideas to share. I started with the nose wheel fairing because there is only one of it so I only have to make one test sample, and I disliked the original nose wheel fairing more than the main wheel fairings. > > To improve on something, one first has to identify the shortcomings. For me, the shortcomings of the original fairing are: > > 1) Poor fit. We all experienced that the thing was impossible to get symmetric. (I have been told that the company now corrected this error but that didn't solve my problem with the already bought fairing). > 2) It is wider than necessary. Apart from the obvious aerodynamic disadvantage, the extra width also implies that the fairing has to bend in sharply at the underside to meet up with the smaller wheel. This bend further creates interference drag, and it increases vulnerability to objects on the ground. Ideally, the fairing's bottom should not be wider than the track of the wheel. > 3) Too weak. Partly as a result of the width, but also due to the material itself. > 4) The vertical division into two halves. These halves do not match well together, they meet at an angle and often bulge out, disrupting the airflow up front and negating the main purpose of the rest of the fairing behind it. > 5) The clutter caused by all the fasteners, all on a separate height. Add a hole at the axle for a tow bar, and there are 5 levels (on each side!) where the airflow gets disrupted. > 6) Too small in height. I would like to hide more of the wheel, and I also would like to fair in my 3cm shaft extension. (This mod was necessary to allow a larger diameter prop and still maintain enough ground clearance). > 7) Too short. The length might be theoretically right, but if the fairing is not aligned perfectly with the airflow it should be longer to allow a shallow decline of the "downwind" side of the fairing to keep the airflow attached. And the fairing is likely not aligned perfectly, due to the proximity of the prop, and it is also quite possible that during take off the nose wheel turns a bit to a side while leaving the ground, especially while taking of in a cross wind. > > How did I improve on all this? > 1) A key decision was to make the fairing from aramide (kevlar) instead of glass. Aramide has less tensile strength than glass or carbon, but it won't crack and it is highly resistant to impact forces. If it is literally(!) bullet proof, it should also cope well with rocks and bumps. The downside is that the material is hard to handle, you can forget about using normal scissors and knifes. We made part of a test fairing with two layups of aramide and had great fun trying to destroy it once it was cured. We jumped on it so it pancaked, but it just popped back into shape after we left it, without any damage. We actually folded it, the epoxy itself cracked a bit but not a single strand broke and it folded right back into its original shape (but of course this time with a visible fold line). If I were living in the US I would probably also have fired some bullets at it just for laughs. This material allowed me to make a much deeper fairing and still don't have to worry about soft fields and hitting some rocks, while keeping the weight low at the same time. On the final fairing we tested it by taking the wheel off the ground, putting obstacles below the fairing and putting the aircraft on its own weight again, so that the entire weight of the aircraft was resting on the fairing. No problem. It will probably survive a flat tire with only some paint damage. We could probably land on it without any wheel inside at all. > 2) A decision was made to keep the axle nuts outside of the fairing. We needed an attach point for the tow bar anyway, and it would either be a hole or a small protrusion. By keeping the axle ends outside of the fairing I could make the fairing more than 5 cm (2 inches) smaller! Also, I could eliminate the arms (saving additional width and weight) and fasteners (leaving the rest of the fairing smooth), by just embedding two metal plates in the layups and using the axle bolts itself to fasten the fairing. Now the fairing got significantly smaller, also the theoretical length would be smaller. Because I wanted a longer fairing, I just kept the length of the original fairing to get the ratio I wanted. And because the fairing is so small, it is easy to make a natural transition into the wheel at the bottom of the fairing without any curve or flat part on the sides of the underside. > 3) Instead of the vertical division, I wanted a lengthwise division so the cut would be in line with the airflow. Instead of dividing it into two halves, Ilona came up with the idea to make a cut so that a part of the bottom can be taken off. This allows the wheel to enter, and it makes the vulnerable bottom part to be easily replaceable. Also, it gives the interesting option to fly with the bottom removed in winter time, to give more clearance for the wheel and to allow mud and snow to fall out by itself. > > A few notes: > The upper part of the fairing is wider than the lower part. This is because the upper part must also encapsulate the yoke. If then a straight angle to the rear is followed, the rear of the fairing automatically gets this "swept back" appearance and its curved underside. This is also the reason that the "nose" is above the center of the wheel. > Of course the bottom of the fairing is a bit of a compromise to get enough clearance on ramps and to blend in the profile of the wheel as good as possible. > The "skirts" on the side are purposedly not rigid. They will give way if something catches between the tire and the skirt. > I made the shape of blue foam, and decided to leave it inside except of course for the cavity of the wheel. This adds further strength for a very low weight penalty. > There is a small "bulge" in the division cut on the port side, this is to facilitate access to the valve of the tire. I only have to drop the underside of the fairing to get access to it. > To remove the entire fairing, the wheel assembly must be taken off. There is however not much need to remove the fairing, as even the wheel can be taken out of the yoke without removing the upper part of the fairing. > The fairing is reinforced near the shaft. This forms the third attachment point, so that the fairing can not rotate over the axle. > There is additional clearance at the rear of the tire, so the wheel can never "catch" the fairing. > The yellow appearance of the fairing is due to the color of the aramide cloth. The ragged appearance of edges is also due to the aramide. Of course the fairing will receive a proper finish. > > This is a one of design, however if someone wants to use it as a plug that is possible. Keep in mind though that it is designed for nose wheel assemblies with a 3cm longer shaft than original. > > Frans > <compare.jpeg> > <front.jpeg> > <side.jpeg> > <top.jpeg> > <underside_closed.jpeg> > <underside_opie.jpeg>


    Message 12


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    Time: 03:38:51 PM PST US
    From: Frans Veldman <frans@privatepilots.nl>
    Subject: Re: Wheel fairings
    On 08/19/2012 10:41 PM, craig wrote: > --> Europa-List message posted by: "craig"<craigb@onthenet.com.au> > > Frans, could you elaborate on the "correct length would be shorter" wouldn't > the longer shallower transition > Create less drag and thus make your longer fairing more efficient. There is also something like skin drag. More surface creates more drag. So there is an optimum somewhere: for a 2D fairing (like for a strut or a wheel leg) the optimal width to length ratio would be 1:3.7, with the widest point at about 30% of the length. For a 3D fairing things get a bit more complicated. Shorter carries a higher penalty than longer, so if in doubt just make it longer. Frans




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