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The M25
Posted: Tue Jul 20, 2010 6:39 pm
by metiz
This is an engine I've been working on. It's a Chinese, dual intakes and a couple mm over 1m. The expected thrust is just about 26 pounds.
It had its maiden testrun tonight - it'll be one I won't soon forget.... the engine mounting came undone and the engine went apeshit - Watch the
carnage here!
Damage report:
1 burned through air hose
1 burned pair of pants
a slightly bruised ankle
ignition box ripped to pieces (ignition still works!)
the engine smashed into my air compressor offsetting the sparkplug by 45 degrees and buckling the endcap
Slightly deformed tailpipe (easily fixed)
So yeah quite the test
I couldn't acurately determine the thrust but just before Armageddon commenced I was looking at the thrust gage - between 12 and 13kg with 300 grams of test stand resistance. I will retest this thing as soon as possible to get some acurate readings. Oh yeah it was 30 degress celsius so this engine will blow even harder when it's cold
When I complete the testing I'll release the plans.
Re: The M25
Posted: Tue Jul 20, 2010 9:20 pm
by PyroJoe
It's ALIVE!
and taking casualties at that.
Good to see you got her shut down in short order.
Re: The M25
Posted: Tue Jul 20, 2010 9:49 pm
by metiz
I got to replace the sparkplug, my pants and the airhose but at least I've got it on film - made me chuckle
Re: The M25
Posted: Tue Jul 20, 2010 10:01 pm
by parabellum
And she strikes back! Today’s lesson: don’t play with fire.
P.S. Very nice engine. (I do not have access to stainless steel)
Re: The M25
Posted: Sat Jul 24, 2010 3:03 am
by Mike Everman
Nice, man, nice.
Re: The M25
Posted: Mon Jul 26, 2010 9:22 am
by Jutte
Awesome...LOL !
Metiz - you're the inventor of the pulse jet powered skipping rope!
Almost a circular travelling pulse jet...woohoo !
Good to see that you're OK !
Re: The M25
Posted: Thu Aug 05, 2010 12:56 pm
by ace_fedde
metiz wrote:It had its maiden testrun tonight - it'll be one I won't soon forget.... the engine mounting came undone and the engine went apeshit - Watch the
carnage here!
Haha ha,
Hahhaaahaha,
haha
haaaaahaaaahaaaa,
haha
uhh?
beh hehe beeeehh hehe,
Mama says "No more Pulse jet extravaganza with that dangerous type!!"
Beh hehe
Beeeeeeh hehehe
Re: The M25
Posted: Fri Aug 06, 2010 5:32 pm
by nickwilson
Good job metiz! The big PJ is that the M40 with the three pice intake you wanted me to try. If so dose it help it out in any way thanks Nick Wilson
Re: The M25
Posted: Fri Aug 06, 2010 7:06 pm
by metiz
Yes that's the M40 with the 3 piece intakes. The reason I asked you to use those 3 piece intakes instead of the 2 piece intakes is that they are guaranteed to work. I'm 99% certain the 2 piece intakes will do just as well but i have not tested this so I can't confirm the last 1%
Re: The M25
Posted: Sat Aug 07, 2010 2:17 pm
by metiz
I ran the engine again today. no unsuspected problems this time but the thrust was a bit dissapointing. I only got 24 pounds where in the the last test I got close to 27. I blame the propane tankt for not giving me enough pressure and the injectors as well
This engine is a real pain to start. I will have to rethink the injector position
Video:
http://www.youtube.com/watch?v=ogOCHdECdN8
Re: The M25
Posted: Sun Aug 08, 2010 8:53 am
by Ghrey
We have lift off...
Seriously; it is nice to see a strong runner in the smaller size range. Nice work.
Re: The M25
Posted: Mon Aug 09, 2010 8:00 pm
by metiz
Hey Ghrey, thanks
Alrighty test 3. I got it pretty close to full throttle this time, not much more, if anything to gain
Final peak thrust is
26.4 pounds wich is pretty sweet. Sustained thrust is about 25.7 pounds
I'll prepare the plans tomorrow - and somebody had better build the fucker
video
Re: The M25
Posted: Tue Aug 10, 2010 3:04 pm
by PyroJoe
Looks like a good one!
It seemed to maintain the high frequency, but lost amplitude as the throttle was reduced.
Not that it is good or bad, I just notice the same characteristics on engines I built with shortish rectifier lengths. They also tended to have that same start up mode with a pop-pop-pop- then go. A little longer rectfier lengths tend to fall into resonance a little easier and will stay locked in more strongly as the throttle is reduced. As a general recipe I began using 44% of the tail unexpanded.
What is your opinion on the low throttle side.
Looks like your hitting good on the high throttle side! That thing must be deafening
Re: The M25
Posted: Tue Aug 10, 2010 3:31 pm
by metiz
Hey Joe
Throttle on these engines is limited, but not absent. Starting is easiest at fairly high throttle. After the engine heats up, the throttle is much more responsive and can tollerate lower settings. Longer rectifiers might alow for a lower minimum throttle but shorter, tuned ones alow for the same thrust in a smaller package.
I am very well aware of the length = thrust debate. Regardless of its truthfullness (my opinion on the matter is clear looking at this engine) I'll stick to short and powerfull for now.
*edit*
injector style is also very important. Rossco's don't throttle as well as different designs
Re: The M25
Posted: Tue Aug 10, 2010 4:12 pm
by PyroJoe
No debates here,
just checking if certain characteristics are present.
Good job on a kick butt engine!