Pulsejet-powered Bobcat RC plane (episode 2)

I added some internal ducting to the fuselage to try and get more air to the engine. This helped a little as it doesn't short-cycle any more but it's still running far, far too rich due to the restricted air intake and the effect my ducting had on the intake resonance of the engine.

You can see a lick of yellow flame as the plane rolls out on takeoff -- a sure indicator that it's too rich.

I aborted the flight early because the rear canopy screw had come out and the canopy was left flapping in the breeze -- this also seemed to reduce the power even more -- probably because air was being sucked out of the gap that formed at the rear of the canopy, further starving the engine of air.

The next step is to make even bigger ducts that also act as a diffuser and try to dampen the resonance that seems to be upsetting the intake tuning.

Category:

Sports

Tags:

• pulsejet
• pulse-jet
• Pulsorohr
• rc
• model
• plane
• remote
• control
• turbine

[iamzoli]

did you give up on bobcat ?

[xjet]

No... it's been winter/spring here so the weather's been not too good. I flew it again last weekend though and hope to fly it (with video camera at the ready) again next weekend.

[qman11112]

what is it running on fuel wise and what is cooling can i assume air. and how much does it hold

[xjet]

It's running on regular gasoline and is cooled by the air that passes over it in flight.  The fuel tank is 20 oz (600ml) and there was about 50ml left when I landed. Normally this amount of fuel would last around 3 minutes.

[bluedog1976]

Who does the pulsejet compare to the ic engine with vibration? any thing special in regards to mounting? Really get a kick out of watching you mad buggers over there.

[xjet]

Vibration levels aren't too bad actually. I think an IC engine vibrates more because the plane of the vibration is up and down whereas the pulsejet's vibrations are front to back. Hold a ruler over the edge of a table and flick the end with your finger -- the vibration is high. Now flick the end but flick along the length of the ruler -- it doesn't vibrate like it did when the plane of vibration was at right angles.

[kelmag13]

pause at 0:21 ...afterburner

[jarikcbol]

look at xjet's other videos, he has one that explains how exactly they work/what goes into making one.

[jarikcbol]

no, because a ramjet requires high airspeed to run, a pulsejet can run sitting still. they *are* similar, but that particular detail sets them apart.

[cyberflyer]

Keep trying!!! There must be a way to get enough air into it!

[iamzoli]

glad to hear sir, i do believe in jet pulse i must admit that i was watching your progress for some time. As soon as it seems to fly without problems i will try myself. |Keep up the good work

[kitingboarding]

much better........ keep up the good work sir.....! can't wait to see more progress.

what thrust should your engine be producing? she can't be far a driff.

[homerdrivesfast]

wow those things are fast, ive liked ppulse jets for some time now but never seen them in planes. My teachers dad flys them alotand also some turbines like you

[ausviking1]

I would look at making the ducting a little larger, each side with the same area as the cross section of the combustion chamber, and I'd also house the front half at least of the pulse jet, to use the surrounding airflow to smooth out the irregularities caused by the indirect airflow, and will also help cool the chamber and pipe. pulse jets are prone to problems if they dont get a clean air feed.  I wonder if running methanol would help too? or a blend?