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Speed,Combat,Scale,Racing => Speed Talk => Topic started by: Joey Mathison 9806 on January 08, 2007, 06:59:51 PM
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some of the jets here in sin city.
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Joey how many of these engines do you currently run?? And the one with the large intake looks interesting
Robert
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i ran the one with the large intake once it did 190 so it is on the back burner the dyna's are retired the bailly sport jet has not been run. then there is a couple of ravens don't run those either. the ones i run are on the planes now ready to fly. a bailey and a raven both of these do desent times.
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Some other worm burners... f~
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very nice looks like you have fun with them
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Joey
In your top picture the top two and the bottom one appear to be necked down just after the burner can and at the start of the tail pipe. Why, or is this an optical illusion?
Clancy
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yes they have a slight mega=phone shape, it helps with the power as 66% of your combustion air comes in from the rear or up the tail pipe.
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Hey loey where you get that 66% from . Last I checked that remaines a mystery if there is a charge of air after exhaust. JB
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ask bill pardue he will tell you all about the wind tunnel study
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Joey and Bill,
Flow into the tailpipe of pulsejets has been mapped for a long time. Static tests show lots of flow up the pipe, depending on shape of the pipe end. Static thrust is improved by a big bellmouth which boosts inflow (called "augmentation" in the aero texts which deal with pulsejets- most were written beforte 1955). As the engine accellerates, flow up the tailpipe decreases until (depending on a lot of things) at about 200-250MPH inflow goes to zero. The Schmidt/Argus engine in the V-1 cruise missile originally had a bellmouth at the exit, and was able to take off on its own in early tests. Flight speed was slow- the trade-off to eliminate the bellmouth, and use a catapult to make up for loss of static thrust ( together with a couple of other speed secrets), increased speed by over 100MPH.
Bill, when you get to making pipes, try some with no flare and see what happens. Static thrust will probably get pretty bad, but top speed may jump, like it did for the Germans.
Will
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I remember something in a NASA study about notching the tail pipe with a 45º notch on two sides for more thrust .I never tried it .Langley or early NASA did a study on dina jets to use on helicopter blades. I didn’t understand it so I gave the papers to Bill Pardue. next year jet record went from the 190’s too 213 mph I always wondered if Bill used any of that information. Bill?
Willis ;D