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CJ LERX

 
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cpayne(at)joimail.com
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PostPosted: Tue Jan 13, 2009 3:39 pm    Post subject: CJ LERX Reply with quote
See attached, pix of my Leading Edge Root Extensions (LERX) prototype. The design is based on tuft testing of airflows and the purpose is to help keep exhaust fumes down under the fuselage, along with the exhaust tip extensions and stub fairings I make.

I have begun some flight testing for handling and stability. No CO monitoring yet, first I want to see if handling has been hurt. On the contrary, no ill effects have been detected in slow flight or coordinated stalls. Aggravated stalls and spin tests are next, along with more tuft testing.

One item of note, stalls seem to occur at a higher deck angle than before. I do not have an AOA gauge. See at at Waycross.


Craig Payne
cpayne(at)joimail.com (cpayne(at)joimail.com)

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vectorwarbirds(at)aol.com
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PostPosted: Tue Jan 13, 2009 4:56 pm    Post subject: CJ LERX Reply with quote
We have found that about 50% of the all the exhaust coming into the cockpit is doing so thought the oil cooler inlet and exhaust.





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cpayne(at)joimail.com
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PostPosted: Wed Jan 14, 2009 5:32 am    Post subject: CJ LERX Reply with quote
>
> We have found that about 50% of the all the exhaust coming into the cockpit is doing so thought the oil cooler inlet and exhaust
>

Was that with exhaust tip extensions or standard exhaust? Through *much* trial and error by many of us some years back, numerous infiltration paths were identified. Lots of CO was coming into the cockpit through holes in the fuselage, such as in the wheel wells and firewall. The path to the cockit was not a straight one, lots of flow into the rear fuselage, under-cabin and then up into the cabin.

Numerous fixes work, extra venting, etc. One problem that remains is the up flow over the wing roots when the AOA increases. This is an attempt to sort out some of that flow.


Craig Payne
cpayne(at)joimail.com (cpayne(at)joimail.com)



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dougsappllc(at)gmail.com
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PostPosted: Wed Jan 14, 2009 12:04 pm    Post subject: CJ LERX Reply with quote
Guys,
In my experience CO in the cockpit really has more to do with internal cockpit pressure than anything else. Plugging up the holes helps but your never going to plug them all. As long as the pressure inside is LESS than the pressure outside your are going to have infiltration of gasses into the cockpit.

However if you cause the air pressure inside to EXCEED the pressure outside and you will stop the problem. To do this you must introduce additional clean air into the cockpit via ram air or some other method. Sucking air out of the cockpit via louver in the tail or other venturi device will reduce the amount of CO but only by "air washing" the cockpit. This is an effective way to help mitigate the problem in AZ or FL but if you live and fly in the cooler regions this is not a useful fix for the problem.

Installation of NACA scoops like BJ Kennamore did, feeding high pressure air to pressurise the cockpit works well. This air could be easily routed to resistance type heaters, another fix is the installation of a ram air vent in the gills to feed clean high pressure air to a heat exchanger in the exhaust system, then into the cockpit.  Resistance type aircraft heaters are available from DC Thermal. Exhaust cabin heaters are found on Yak 52's and Yak 18T's, some models of Wilga may also work on the 285 hp engines, but I have no experience with them.


Always Yakin,
Doug



On Wed, Jan 14, 2009 at 5:30 AM, Craig Payne <cpayne(at)joimail.com (cpayne(at)joimail.com)> wrote:
Quote:

>
> We have found that about 50% of the all the exhaust coming into the cockpit is doing so thought the oil cooler inlet and exhaust
>

Was that with exhaust tip extensions or standard exhaust? Through  *much* trial and error by many of us some years back, numerous infiltration paths were identified. Lots of CO was coming into the cockpit through holes in the fuselage, such as in the wheel wells and firewall. The path to the cockit was not a straight one, lots of flow into the rear fuselage, under-cabin and then up into the cabin.

Numerous fixes work, extra venting, etc. One problem that remains is the up flow over the wing roots when the AOA increases. This is an attempt to sort out some of that flow.


Craig Payne
cpayne(at)joimail.com (cpayne(at)joimail.com)



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Always Yakin,
Doug Sapp
Phone 509-826-4610
Fax 509-826-3644
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flushjohnson(at)charter.n
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PostPosted: Thu Jan 15, 2009 10:56 am    Post subject: CJ LERX Reply with quote
Craig,
Please email me your mailing address. I need to send a thank you note for flowers.
Thank you,
Martha Johnson

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