This was posted in Australia recently and I could say the original cowl flap install in Australia was done by Fieldair Ballaret in Victoria (my contact there was Kevin Howard if he is still working) and that would have been done 25years ago - They flew Pawnees for 33years. I am not sure if they did their own engineering or was done by Daffyd Llwellyn of Southdown Engineering (we call Reg 35 engineer). The team that progressed the Pawnee in Australia were Gippsland Aeronautics (Peter Furlong, George Morgan and now Jonathan Shand - all gliding or ex people) They redid the Pawnee and it is now a new type called GA200 Fatman. They chose not to have cowl flaps but better sorted out airflow. One thing was to smooth up the underside of cowl so that there is an upside-down airfoil on the underside. It is done in foam and skinned in glass and we can all do that to any aircraft. Also air is extracted at side of cowl rather than all underneath (Pawnee) in the high pressure area. Another problem area in many aircraft is air going in around the exhaust pipe so a deflector in front of exhaust pipe is a good idea and gets the air flow in correct direction. Also never fly without a spinner - it is all part of airflow smoothly going into engine. This gives more airflow on climb and thus the max temp does not rise as high and thus less chance of cracking. The shock cooling damage is done by shock cooling from high temp to medium not medium to low temp. If you can knock even 10deg off max temp in climb then you are winning. If you fit cowl flaps then I would recommend micro switches (even dry cell battery operated) on max throttle and cowl closed so you do not do a take off with flap closed - Darling Downs Soaring Club have this on their Pawnee. Alternatively or as well fit a KSAvionics http://www.ksavionics.com ([EMAIL PROTECTED] Bill Simpkinson) shock cooling alert with flashing light and audio alarm which also warns if cowl flap closed on takeoff but 17 sec delay. You can also set the max temp light at the deg C you want. Neil Dunn monitors all 4 cylinders has accurate figures on a C150 -180hp they use for glider towing at Kingaroy and I could say this tug beats a Pawnee 235 or equals the Pawnee 250hp. If towing low speed gliders (ASK13 etc) it seems best to use one notch of flap as this lowers the Pawnee nose and gets better airflow through the engine. I recommend when you get your Pawnee back from 100hly from LAME you really check the rubber seals that they are doing their job. I have seen the top cowl put on by engineer with rubber bending backwards which is all but useless. Also when they have worked on cylinders etc they have not sealed it up like it was when it went in for service - you pick it one flight if you have a dig CHT and you know your aircraft. The average engineer unless he is a tow pilot or real smart does not worry about these things like he should as he has no concept of our shock cooling problem. When all else fails get out the silicon gun and start sealing yourself - all air must go through the fins especially the heads. Give me a few days and I will find who had the engineering order for the cowl flap on the Pawnee. While on Pawnees I like the way Gippsland Aeronautics have mounted the tow release to one side so you do not need rudder while towing - thats smart and we should do it on all tow planes to make the tug pilots life easier. There you have my thoughts. Ian McPhee Box 657 Byron Bay NSW 2481 Australia Tel +61 (0)2 66 847 642 Mob +61 (0)428 847 642 [EMAIL PROTECTED]
----- Original Message ----- From: "Leigh Youdale" <[EMAIL PROTECTED]> To: "Aus-Soaring" <[EMAIL PROTECTED]> Sent: Sunday, October 19, 2003 12:05 AM Subject: [aus-soaring] Pawnee Query re Lycoming Thermal Engine Shock > In the October-November issue of Sailplane and Gliding a letter writer > asks (in part) ... > "... at one time had a visit from my opposite number in the Australian > CAA .... in the discussions I was told that there was an Australian > modification to fit a cowl flap to the cowl exit on Pawnee aircraft to > alleviate the shock cooling when throttling back following a full power > climb. Over the years I have tried to find references to this mod but > without success." > > The writer is Jim Tucker. If anyone has the info requested they might > like to respond directly to <[EMAIL PROTECTED]> > > Leigh Youdale > > > -- > * You are subscribed to the aus-soaring mailing list. > * To Unsubscribe: send email to [EMAIL PROTECTED] > * with "unsubscribe aus-soaring" in the body of the message > * or with "help" in the body of the message for more information. > -- * You are subscribed to the aus-soaring mailing list. * To Unsubscribe: send email to [EMAIL PROTECTED] * with "unsubscribe aus-soaring" in the body of the message * or with "help" in the body of the message for more information.
