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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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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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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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
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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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Subject: | Re: rotax 912S grounding strap position |
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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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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Subject: | Master Brake Cylinder Mono |
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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Subject: | Landing mishap - asking for advise |
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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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.
>
>
>
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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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Subject: | Re: Wheel fairings |
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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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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