Exhaust duct thrust loss
07-21-2002, 06:13 PM
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Exhaust duct thrust loss
I just retrofitted my Avond's F-104 with a Simjet 3000 with 12,5 kg thrust, replacing a JetCat P-80.
Other than that I now can "cruise" with 40% power instead of 80% with the P-80, there's a marginal improvements at full power.
The thrust loss in my exhaust ducting seems to be very high.
Has any one found the optimum measurements for the exhaust ducting on a Avond's F-104 or another A/C with long exhaustpipe?
My pipe is about 594mm in lenght, inlet dia.is 93mm, exhaust dia. 82mm and I have an 18mm long gap between the engine and the start of the pipe, and a 16mm space between the end of the pipe and the end of the ducting.
Propsareforboats
Other than that I now can "cruise" with 40% power instead of 80% with the P-80, there's a marginal improvements at full power.
The thrust loss in my exhaust ducting seems to be very high.
Has any one found the optimum measurements for the exhaust ducting on a Avond's F-104 or another A/C with long exhaustpipe?
My pipe is about 594mm in lenght, inlet dia.is 93mm, exhaust dia. 82mm and I have an 18mm long gap between the engine and the start of the pipe, and a 16mm space between the end of the pipe and the end of the ducting.
Propsareforboats
07-22-2002, 12:30 AM
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Exhaust duct thrust loss
From what I recall from Tam's pipes and some of the numbers he put to the inlet and exhaust diameters, there was less of a decrease (i.e. not that large of a taper) from the front of the thrust tube to the rear. I would think that if your 93 mm is correct( I'm not familiar with the turbine outlet size of a Simjet 3000 ), then your outlet diameter would be closer to 90 mm... I hope Tam decides to chime in here....
