Hi Frans,
thanks for your thoughts - they are more or less a
careful analysis (as your mails usually always
are).
I will comment a bit between lines with *** :
-----Alkuperinen viesti-----
From: Frans Veldman
Sent: Thursday, July 21, 2011 7:45 PM
Subject: Re: Europa-List: Tire /tyre landing
incident /accident
<frans@privatepilots.nl>
On 07/21/2011 04:49 PM, Raimo Toivio wrote:
> I purchased and got today a tyre *pre-puncture*
> liquid from Netherlands.
> I have it 25 liter = about 6 gallons and I need
> it only 0,25 liters.
Just a few thoughts:
1) It is available in 1/4 liters bottles as well,
so you could have
saved quite some money.
*** They have 25 liters and 1 liters botles only.
They sell also 1/4 liters "pump pushes direct from
the canister" but no botles. As I wrote earlier, I
do not fly to save money. 25 liters of that staff
will go sooner or later. Maybe some day we will
put 3x0,25 liter to your trike...
2) According to the website it is only for
punctures in the thread, not
in the sidewalls. But if I remember correctly the
sidewalls is where the
monowheels usually develop the leaks.
*** Correct, mostly for punctures in the thread. I
have had four (4) tube punctures; two times in the
sidewalls, two times in the threads. So, I counted
it could prevent some puncture cases.
3) According to the website it is for slow moving
vehicles only. But I
wouldn't exactly describe an Europa as a slow
moving vehicle.
*** When taxiing my speed is around 20 knots. I
feel it is quite slow. During typical flight I
taxi about 2-4 km before dep and after arr using
that (slow) speed via all kind of taxiways and
grass and what so ever surface. During take off
with "high speed" max 60 knots only let us say 200
m and during landing another 200 m with "high"
speed and using most cases high quality asphalt
without sharp rocks, nails and other possible shit
making punctures. 10% high speed, 90% low speed
taxi. So...
4) They also say that it can be washed
away with water if you want to
repair the tire. I'm not sure what to think about
this: Does it also
mean that when you fly through the rain the stuff
dissolves? You might
not even know that you had a leak previously but
suddenly the tire
empties and you are in for a surprise when you
land on the wet runway.
***Come on! Those "slow moving vehicles" are
moving also when raining. If the stuff dissolved
when wet it would be totally unusefull! It cannot
do that, not possible. When it fills the hole, it
will not dissolve any more. They claim it will
fill the hole diameter even 16 mm!
5) The stuff remains liquid inside the tire.
During landing the wheel
accelerates in a very short time when the wheel
makes initial contact
with the runway. The liquid stuff inside the tire
has inertia and I'm
not sure what the effect will be. For sure it will
have a lot of
friction for a short moment, and it may give a
massive imbalance when it
has piled up on the bottom of the tire during
flight and suddenly has to
rotate very fast, just like a washing machine that
starts to hop when
the laundry piled up on one side. You might be the
inventor of the
"self-bouncing monowheel". This imbalance may be
the reason why it is
described as "for slow moving vehicles only".
*** That is something what I have wondered also.
The radius of the tube is around 0,2 m. The mass
of the stuff is around 0,3 kg. The max speed of
the tire is about 60 knots = 31 m/s. That means
the tyre is revolving about 1500 rpm = 25 r/s. But
only a short moment. The stuff itself BTW is not
so liquid, it is more or less like let us say
micro slurry or it has a form of existence like
porridge. That means it will be always more or
less everywhere in the tube.
"Self-bouncing monowheel": I liked that much! Let
us wish that effect will compensate so common
"Pilot induced bouncing effect".
So, be careful here!
*** I promise!
You might want to add the stuff in stages and test
each stage with an actual landing to see how it
behaves.
*** Good idea but I am too lazy to do that!
Also, what is the effect of temperature on that
liquid stuff? Will it
become a jelly like lump inside the tire if it
gets too cold? Maybe put
it overnight in a freezer and see what becomes of
it.
***They claimed -40C but it is a good idea to put
some of it to the freezer.
> Price: 550 euros /canister. As I wrote I am not
> saveing when it is the
> question of my or my familys (flight) safety.
I fully agree but you should make sure you are not
trading one risk for
another.
*** There are almost always double sides, blacks
and whites. I have decided to do my everything to
not suffer any more punctures. Maybe I will get
other problems instead of that. That is my way to
go anyway.
If this stuff really works one would expect that
it would be
used already widely in the airplane industry.
***
Why not:
1) it is not certified for aviation use.
2) there are many let us say "good and well known
safety manners or products" but they are not in
use, from one reason or other. For example BRS and
airbags really works but they are not widely used
so far.
3) I had C172 more than 12 years and never tyre
punctures. That problem is not so common
obviously.
4) money, labour
5) large planes with many tires, loosing one is
maybe a minor case.
***
I am almost sure the main problem is the tube
brand name Deli and their low level production
quality. It is so cheap that how it could be good?
Frans, please comment Rob Robsons ( Sales
Manager - General Aviation Goodyear Aviation Tires
Phone: 330.796.1596 Cell: 330.283.8704
www.goodyearaviation.com ) idea below (that brand
name is something I could trust):
1. Try a G15/6.00-6 tube with a TR-67 valve (which
is a bent 90-deg valve). The 7.00-6 tire is
roughly 1 1/4" taller and 3/4" wider than a 6.00-6
tire, so the tube will most likely stretch to fit.
Thanks, Raimo
BTW: tomorrow I will head to Utsjoki, which is
practically northernmost point in Finland and
about 370 km north from Polar Circle. I will fly
daughter Tuuli. Wish us safe landings with a full
tube! I have no spare tube with me, the shipment
was unfortunately late.
We will met Jos (you remember) in Ivalo. May I
tell wishes for him from all of you?
Raimo OH-XRT Finland
Frans
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