>>>>>> I had the opportunity to hear a renesis motor on a Jabaru
>>>>>> yesterday.
>>>>>> It had
>>>>>> NO muffler at all and made less noise than a Lyco. I was
>>>>>> expecting
>>>>>> to be
>>>>>> deafened but I was extremely impressed with the note.
>>>>>>
>>>>>> I was standing about 12 feet to the side at one point
and when
>>>>>> the
>>>>>> pilot
>>>>>> revved it up to 4000rpm I was standing at the tail
holding it
>>>>>> down
>>>>>> and the
>>>>>> noise was not overly loud. The cowls were off at the
time so I
>>>>>> imagine that
>>>>>> it would be even quieter with them on.
>>>>>>
>>>>>> The white wrapping on the exhaust pipe is some old
asbestos wrap.
>>>>>>
>>>>>> Greg
>>>>>>
>>>>>>
>>>>>> That exhaust wrap is very dangerous. First; the rotary
exhaust
>>>>>> temperature
>>>>>> and frequency is higher so it is very hard on metal
pipes. Two;
>>>>>> it
>>>>>> is difficult
>>>>>> to inspect for cracks. Not recommended. We have had a couple
>>>>>> of crashes for this reason.
>>>>>>
>>>>>> --
>>>>>> Paul Lamar ...No rotor no motor.
>>>>>>
>>>>>> Hey Greg, what prop is that. Looks ground adjustable at a
minimun.
>>>>>> Is
>>>>>> it a warp drive?
>>>>>> BTW, I mostly agree with Paul about the wrap. Besides it being
>>>>>> ASBESTOS, they are problematic but can be made to work. You
need
>>>>>> something rated to 2000 deg., don't let it cover any welds,
and it is
>>>>>> best to have a cerramic coating on the exhaust to minimize
>>>>>> corrosion..
>>>>>> Will corrode very quickly under the wrap without the coating.
>>>>>> --
>>>>>> David Leonard
>>>>>
>>>>>
>>>>> Thanks for you're comment and I'll pass them on.
>>>>> The prop is branded Cobra Aviation (Australian), but I thnk
it's made
>>>>> by
>>>>> Bolly. It is variable pitch controlled by oil pressure using
a Sub4
>>>>> PSRU. I
>>>>> can't remember whether it was constant speed or not.
>>>>>
>>>>> Greg
>>>>>
>>>>
>>>>
>>>> The prop is probably made by Bolly for Cobra Aviation and the
hub is in
>>>> flight adjustable ( hydraulic ) but not a true constant speed.
There
>>>> are
>>>> 2
>>>> methods of in flight adjustment. One is electric pump, the
other is
>>>> manual
>>>> knob on a master cylinder instead of electric pump.
>>>>
>>>> Baz
>>>>
>>>> How are you doing Baz? I take it you and your rotary powered
airplane
>>>> are
>>>> now living happily together after you got the pitch stability
>>>> fixed. Got any performance or cooling data to report?
>>>> --
>>>> Paul Lamar ...No rotor no motor.
>>>
>>>
>>> G'day Paul,
>>> Yep, the anti servo tab made all the difference. I'm having
problems
>>> with
>>> controlling the prop pitch. I think there is still air in the
hydraulic
>>> pipe
>>> somewhere as the pitch doesn't stay stable. The aircraft is
stable and
>>> yesterday ( in rough turbulent air ) I recorded the following
OAT 25C
>>> [77
>>> F],
>>> elevation 475', take off with reduced power ( 4300 rpm ) 500metres,
>>> climb
>>> 90
>>> knots @ 1500 '/min to 5,500'. Temps on climb coolant 88C [190
F], oil
>>> 98C
>>> [208 F], Straight
>>> and level 4600 rpm, 136 knots TAS, fuel flow 33 litres[8.7
gal]/ hour,
>>> coolant [80C 176 F],
>>> oil 90C [194 f].
>>> The prop pitch seems to wander a lot which leads me to believe
there is
>>> air
>>> in the system. Apart from that the engine is super smooth but a bit
>>> noisy.
>>> The reduced power on take off was because the prop pitch isn't
stable
>>> and
>>> I
>>> didn't want to overspeed the engine.
>>> Obviously there is still work to do but getting there. I'm
still very
>>> nervous about it after those first two flights but as it proves
itself
>>> to
>>> me
>>> I will get more confidence in it.
>>>
>>> Baz
>>>
>>> Thanks Baz and thanks for including the OAT. A lot of people
>>> forget that. Looks like your cooling system is working well.
>>>
>>> I take it there are some louvers in the cowl somewhere
>>> to let the air out. Got any recent pictures of the cowl?
>>>
>>> Can't wait to see how fast that little bugger is when you
>>> get the prop fixed.
>>>
>>> Don't worry about over speeding
>>> the engine. When the prop tips go supersonic regardless of the
pitch
>>> the engine RPM will stop increasing. The engine RPM will go to
>>> 9000 RPM or so without hurting it.
>>>
>>> What is the PSRU ratio? Who builds the PSRU?
>>>
>>> I think the engine is running a bit rich.
>>>
>>> Paul Lamar ...No rotor no motor.
>>
>> Hey Baz how close is that exhaust to your nose gear (?) bungees
? Sure
>> looks close. Glad to hear you have the stability issues worked
through,
>> sounds like you had a tiger by the tail those first couple of
flights.
>> Good
>> luck.
>>
>> John
>
>
> Hi Paul,
> There are no louvers in the cowl. I attach a pic of the cowl. The
bottom
> inlet feeds the bottom radiator, the one on the left feeds the side
> radiator
> and the other one feeds the oil cooler. Great care was taken
sealing up
> all
> the inlets and I would think more than 95 % of the air is being used
> effectively. There is a large lipped outlet on the rear of the
bottom cowl
> to get the air out.
> I don't know the manufacturer of the PRSU but it is 2.3 :1 reduction.
> The bungee is not quite as close to the exhaust as it looks in
the other
> pic. I read with interest the comments on exhaust wrap recently
as I have
> just done that to keep heat away from the bungee. The jury is
still out on
> whether it stays on or not.
> How do I go about finding out if its running rich or not and what
can I do
> if it is?
> I wish I was over in W.A. to have a look at that Jabiru.
>
> Baz
>
>
> You will never over rev the engine with a 2.3:1 PSRU.
>
> If you are running unleaded auto gas an O2 sensor/mixture monitor
> works fine. There are many on the market.
>
http://www.knfilters.com/airfuelmonitors.htm
>
> Are you Electronic Fuel Iinjection or carb? Does your carb
> have a mixture control?
>
> The other way is using Exhaust Gas Temperature sensors
> and an EGT gage.
>
> You change the mixture until you see peak EGT
> then slowly lean the mixture to about 150 F (65C) lean of peak.
>
> If EFI many EFI computers have mixture controls. Some you must
> program it off line.
>
> In that case you need the O2 sensor/mixture monitor.
>
> Paul Lamar ...No rotor no motor.
G'day Paul,
I'm using Avgas, the engine is Electronic fuel injection and a Wolf
ECU.
Maybe when I've got the rest right I will get the ECU adjusted.
Thanks
Baz
The problem with AvGas it destroys O2 sensors.
It also eats rotary spark plugs.
Change your plugs every 50 hours or so.
The first thing you will notice is a reduction in
power. Auto gas they may be good for 100 hours.
--
Paul Lamar ...No rotor no motor.
Does anybody know how the lead destroys the O2 sensors and spark plugs?
I had assumed the problem was that the lead is electrically conductive
which shorts electrical devices (sensors and plugs), but I'm not sure.
I don't think there's any metalic pure lead in fuel (or as a byproduct
of combustion), but lead salts. I guess those salts are probably
conductive though..
Matt-
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