my tip jet ultralight helicopter

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Chris McDonald
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Location: NY, USA

my tip jet ultralight helicopter

Post by Chris McDonald » Sun Dec 19, 2004 3:25 am

Gentlemen,
in '85 my aeroscience project was to build a USA FAR part 103 ultralight helicopter. copter came out great. 21 ft rotor span with a nice working fuel transfer hub. all the mechanical parts work nice. i built two pairs of crude jet engines for it. the big pulse jets i really failed on. the ramjets were as crude if not worse but they did spin the rotors up with just me starting the rotor by reaching up and grabbing it and tossing it over. then i'd climb in give it fuel and spark and they would pop off every time and never flamed out. did not make by far lift rpm but it was impressive. just so you know i will be adding a small gas engine for rotor spool up and fuel pump.
you folks are nice people. it pained me to read old forums about a making an engine test bed when i have one right here. any thoughts are always welcome all my friends share information 100% (nothing ventured = nothing gained)
i think i am favorable to Stan Hillers 8RJ2B ramjets. i could even use his smaller ones since i'm so underweight of the Hornet.
i know there is a guy from your forum who was helping restore a Hiller ram jet Hornet and you all can imagine how much i'd like to talk to him.
there is a photo in my gallery.
peace, power & progress,
chris

Mark
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Joined: Sat Oct 11, 2003 10:14 pm

Re: my tip jet ultralight helicopter

Post by Mark » Sun Dec 19, 2004 3:38 pm

Nice bit of work there. When you say "grabbing it and tossing it over", do the ramjets start that easily at so slow a speed? I picture you just pushing the blades enough to spin them.
The other day I was listening to Al Stewart's album "Year of the Cat." Your quote of "nothing ventured, nothing gained", came to mind.
Mark
http://www.alstewart.com/lyrics/midasshadow.htm
Presentation is Everything

Chris McDonald
Posts: 13
Joined: Fri Dec 17, 2004 4:01 am
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Location: NY, USA

Re: my tip jet ultralight helicopter

Post by Chris McDonald » Sun Dec 19, 2004 10:12 pm

Mark,
you got it right. i would stand on the skid and whup the rotors over by hand harder and faster each time they came around. once spooled up i'd climb in and give it fuel and spark. ka-poof! they lit right up every time. your motto "It's OK to steal. More innovations come from borrowing and combination than simple invention." best describes the engines. they were a bit of everything but back in that day critical parts were left out of the plans so no one would find success that would lead to a lawsuit. eg: they had no flame lock system. also we had not installed the collective and were testing with full 8 degree positive attack pitch blocks on the rotor blades. with that kind of drag at start up the engines may not have been given a fair chance. live and learn...
read my thread to Mike in the pressure jet forum for more info.
stay well,
chris

Chris McDonald
Posts: 13
Joined: Fri Dec 17, 2004 4:01 am
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Location: NY, USA

Re: my tip jet ultralight helicopter

Post by Chris McDonald » Mon Dec 20, 2004 9:17 pm

Mark,
you should look at the patent 5,934,873 at the uspto website. that thing would probably kick with just a serious hand crank of the rotor. it is specific to the design of a helicopter rotor blade though. not hard to build.

Mark
Posts: 10751
Joined: Sat Oct 11, 2003 10:14 pm

Re: my tip jet ultralight helicopter

Post by Mark » Wed Dec 22, 2004 4:38 pm

Chris, thanks for the ramjet #. Interesting placement of the spark plug and how it uses both ram air and centrifugal compression to increase thrust.
Mark
Presentation is Everything

Chris McDonald
Posts: 13
Joined: Fri Dec 17, 2004 4:01 am
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Location: NY, USA

Re: my tip jet ultralight helicopter

Post by Chris McDonald » Fri Dec 24, 2004 12:33 am

Mark,
yes that design does look like an interesting inovation of Stan Hillers Hornet. it's the first i have seen of the added centrifugal compression. even if i did the gluey press jets i'd have to gut out the leading edge of the blade ends for extra intake. i think even before i pick an engine plan i will focus on a mechanical rotor spin up for my hub. either electric or gas engine. that alone will probably be enough to scare my neighbors : )
chris

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