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Grumman Goose ground test question

N

NDORFN

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38
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newzealand
In an original manual it states that start up is down in the DECREASE RPM position, then onto the warm up where it states "During the warm up the engines shall be run at 800-1000RPM in the INCREASE RPM position" and says that the change from high to low pitch should be made about a minute after starting. It makes sense... BUT... in the ground test check list it says that the HG should be 30". I might be ignorant or maybe it is a little ambiguous, but is it safe to assume they mean to start out at 800-1000RPM at say 9", gradually increase the prop control to full then bring up the power to 30" which naturally gives me full RPM, in this case 2300???

I don't even know how a general ground test is done. All the other states in the check list point to it being run at 30" at 2300RPM (oil temp and pressure, CHT and so on)... I guess my main question is, is it normal to do a ground test flat out, loads of power in low pitch, rear wheel hovering off the ground even with ballast and the whole aircraft begging to launch into oblivion?

(I'm using this info to tune the aircraft.cfg)
 
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A typical pre take-off piston engine ground test involves checking each engine at a certain value, less than full power, exercising prop controls through the complete range and noting idle.
The Goose checks as you have pointed out only use 30 inches of boost, which is not much, per engine, one at a time so I doubt it will wag its tail in the air.
If it is on water a different procedure would be needed because opening up one engine at a time will result in it making circles in the water.
In fact just starting one engine at a time can be fun and it is essential to be well clear of any obstacles in the near vicinity.
Roy
 
Thanks Roy. Makes sense and fit with the checklist. I guess 30" isn't all that much considering 35.5" is T/O and they're supercharged too so the resulting thrust at 30" would be exponentially less than 35.5", maybe only about 3/4. Being a tail-dragger it does require 100lbs ballast in the rear empty to top it tipping, which is what the manual recommends so, it seem with all the other prototypical specs I've emulated in FSX, they're starting to come together and perform just how the manuals and videos depict. Man, I just need to make friends with a Goose pilot. Would save me DAYS of work.

P.S Apparently they don't do ground tests on water (closest thing is a pre-takeoff check done at 800RPM less than when on land), but they're amphibious so I guess that's why I never see them docked in water for very long... they always at the least, beach themselves with gear down... easier to deal with a cold and dark start on land.
 
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