Sonic 120 SP questions
10-05-2004, 10:18 PM
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Sonic 120 SP questions
Hello Kevin/Ed,
I've got 15 runs on my Simjet Sonic 120 SP. Runs great, super smooth/quiet since the final balancing, and excellent throttle response. The only concern I have is the peak EGT observed during start (870-900C). These temps are very brief ( 1-2 secs max) but seem awfully high. At idle, EGT settles down to a cool 500C. Is this normal? I tried reducing the amount of propane with the propane valve but saw similar EGTs. Turning down the propane causes me to have to shake the airplane after propane lightoff in order to keep a high enough EGT for the fuel pump to ramp. Any ideas or solutions? Thanks. Terry Harcharik
I've got 15 runs on my Simjet Sonic 120 SP. Runs great, super smooth/quiet since the final balancing, and excellent throttle response. The only concern I have is the peak EGT observed during start (870-900C). These temps are very brief ( 1-2 secs max) but seem awfully high. At idle, EGT settles down to a cool 500C. Is this normal? I tried reducing the amount of propane with the propane valve but saw similar EGTs. Turning down the propane causes me to have to shake the airplane after propane lightoff in order to keep a high enough EGT for the fuel pump to ramp. Any ideas or solutions? Thanks. Terry Harcharik
10-06-2004, 12:08 PM
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RE: Sonic 120 SP questions
Hi Terry,
Although it does sound high, it's probably not off typical. The cause is the rate of acceleration just prior to reaching idle, but it's so quick that the hot parts won't have time to absorb much of this heat; SimJet has been "speed starting" their turbines for years with no ill effects.
Although it does sound high, it's probably not off typical. The cause is the rate of acceleration just prior to reaching idle, but it's so quick that the hot parts won't have time to absorb much of this heat; SimJet has been "speed starting" their turbines for years with no ill effects.
