New rotorcraft concepts

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Bob Kelly

Well-Known Member
Joined
Aug 19, 2004
Messages
373
Location
N.Calif Mountians
I just spent 2 hrs trying to sign up again on that Frigging YAHOO!
and it still won't let me in...says taint no such person!
...LOL !
Howdy Gilbert ! I ain't hurd from Sonny in about 8 months now!
hope he's ok !
I'll try again on the forum.... no silly program is going to get the best of me ! LOL !
Good to see your still Kicking my friend !
...
Bob....
 

Bob Kelly

Well-Known Member
Joined
Aug 19, 2004
Messages
373
Location
N.Calif Mountians
Hay Gilbert ! are you in your sailboat ? if so Where ?
Gary said you were headed to the Carabien or somethin' LOL
... if so don't you know there are easier ways to Torture yourself than be confined in a box for weeks at a time ?
...
Good to hear from ya buddy !
Bob.....
 

pie_row

Well-Known Member
Joined
Nov 9, 2009
Messages
710
Location
salt lake city Ut
Well What I want to do in life is to make very powerful very small engines. This is what I've come up with for a backpack heli. Use a small engine to drive a small turbo compressor. Blowing the air out of the rotar tips. This is a very light power system. A 15hp engine with 15 lbs boost should make 30 hp. and I would dump the exhaust back into the air going out the rotar tips.

The rotodyne that the british built was a falure because it was a bad utilasation of the systemt rather than because the idea didn't work. Where the requirment is driven by somthing other than "practicality" for want of a better word tip jets can be the best choice. Low power low wieght etc. when that is driving the design then the best choise may be tip jets.
 

Bob Kelly

Well-Known Member
Joined
Aug 19, 2004
Messages
373
Location
N.Calif Mountians
The Nitrous Oxide Rocket tips work very good for a BPH... a few guys have tried them, no reverse torque to have to counter and in general they work very good, the only problem is obtaining the fuel as "Rocket Grade" Nitrous Oxide is hard to get and very expensive when you can get it... so that makes the choice impractical at best....
Pressure Jets have been used on Small Helo's for some time and I've even seen a pic of one on a strap on your back copter... dunno if it was ever flone though......problem is those things guzzel up fuel faster than you can spit !...
So I started on the idea of a Pulse Jet version first to power the rotor on my Gyro copter and was going to make a BPH useing them if it worked for the gyro... HOWEVER the Noise was so extreamily Loud that I gave up on them... yah it'ed probably work..but you could only fly it in a desart wwwway out where there is no body to complain about the noise!
although my pulse jets only put out about 2.5lbs of thrust for a 3" PJ... it was enough to show me there has to be a better way !
... using presurized air to turn the rotor should indeed work but the volume you'ed need would be very hard to keep up with yet alonebe able to lift it off the ground...
you might consider a big back pack Lief blower and use it to turn the rotors.... you may need 2 of them but if you could pull it off who cares if it takes 2 leif blowers ?
...
I saw some nice ones at the hardware storeunder $250 and they said 120mph wind out of the 4" nozel.... thats allot of air!
...
good luck
...
Bob.......
 

tyc

Well-Known Member
Joined
Sep 16, 2008
Messages
60
... using presurized air to turn the rotor should indeed work but the volume you'ed need would be very hard to keep up with yet alonebe able to lift it off the ground... you might consider a big back pack Lief blower and use it to turn the rotors.... you may need 2 of them but if you could pull it off who cares if it takes 2 leif blowers ? Bob....
If you haven't already, take a moment or two an seach the Internet for the work done by Zimmerman. He's a Canadian who worked for NACA (before it became NASA) and some of his work could best be described as astonishing; "The Flying Flapjack" is but one of his ideas and the concept of of a flying platform is another; he used shop service 125# air or so to lift a man standing on a plywood sheet! If your interest is along those lines, it'd probably be worth your while to investigate this further. With Zimmerman's flying platform in mind, the other year I came across a website which offers for sale, plans for such a platform. It's intended for kids (and those young at heart) which uses a lawn mower engine and a sheet or two of plywood. A brief glimpse of the photos and the written description left little doubt but that it works as advertised.. Will two leaf blowers do the job to tip-driven rotors? For a single pilot and rotors with a long enough cord, there's no doubt here but that such a contrivance will work. It may not be very efficient but it will work. As for it's practacality, I have some doubts about that but it'd make one whale of an educational project/"toy" for a father-son effort. tyc
 

Bob Kelly

Well-Known Member
Joined
Aug 19, 2004
Messages
373
Location
N.Calif Mountians
Actually I was thinking of the 32cc to 45cc gas powered leaf blowers... not the electric ones... whats the point if ya have to run an extenion cord to it <GRIN>
I have ran a few of the Bigger leaf blowers in my time working for building maintenance at diferent places.. some of them put out a large amount of thrust... easily 20+lbs and they only weigh 10~15lbs... and 90% of that is un needed for a aircraft application... so 4 of them on a sheet of plywood pointing down may indeed get you a hover-craft... but a hovercraft is Not really flying... your still bound to ground effect...and thats not what I had in mind... fling over the tree tops is what I want to do HAHAHAHA
...
Bob........
 

autoreply

Well-Known Member
Joined
Jul 7, 2009
Messages
10,738
Location
Rotterdam, Netherlands
How about using a jet engine to power your tips? Anything turning on your tips will be torn about by the centrifugal forces, but a simple nozzle can be made to last under heavy G's.
Having a jet engine, blowing in the hollow rotor axis and then blowing in the (hollow) blades sounds like the ultimate simple, light weight helo setup.

The Mercury is a proven model engine for just 20 lbf of thrust. At a tip speed of 200 m/s that's 17.5 kw or just under 20 HP of effective power. Should be enough for a normal-sized rotor and if not, the Titan does almost 90 lbf.
 

bmcj

Well-Known Member
HBA Supporter
Joined
Apr 10, 2007
Messages
13,302
Location
Fresno, California
Lifting a man with pressurized air under a sheet of plywood is easy. You are dealing with hovercraft physics here. Rotorcraft physics (and air driven rotors) is a little bit different.
 

Mike_Mercury

New Member
Joined
Mar 3, 2010
Messages
3
Location
Savannah, GA
Greetings. I'm newly registered to HBA.com so I could post a question here. Unfortunately I lost my first post which was eloquently written, informative, insightful, long but still a good read, all due to my login timed out. Now I'm just a grumpy not-so-old man banging away at the keys.

Has anyone seen or heard of any smallish personal tandem (not dual) rotor helicopters flying or in development? I know about the Filper Beta series from the 60's.

There was a whole story that went with this but I'm too pooped.

Thanks for any comments.

mike
 

Mike_Mercury

New Member
Joined
Mar 3, 2010
Messages
3
Location
Savannah, GA
Okay, a little of the story...

I'm interested in the experimental and "unique" side of light avaition. My reason for being on this thread was to fish for info regarding light tandem-rotor helicopters (see Jovair 4E Sedan or Filper Beta series). More specifically, is there anyone here working on such a thing, or contemplating starting a project like this, or have any input as to my sanity for thinking of starting such a project.

After doing a little light reading on the early tandom-rotor designs I was impressed with their horsepower to lift efficiency and the utility of interior space. Plus I have always thought this style was cool, weird right? But remember, I like the unique stuff. At this point I really don't think anyone is doing a homebuilt tandem. Maybe I'll give it a try or a least learn enough to say "nope, too much for me right now".

Design-wise I would say the only real issues are the rotorheads (3 blade) and learning how the control system works. Sourcing parts and lots of money is for another day.

My background? Not much. EAA member for a number of years, though not currently. Helicopter training but didn't get to solo - moved. Did FW training (cheaper) and soloed but then got a real job and a busy family. Started one light plane project along the way - fabric and wood. My wife hated it, and I wasn't happy with my work. Then there were so many official mods to make it safe that the original plans were almost useless. I wouldn't have trusted the outcome.

Thanks for listening.

mike
 

Mike_Mercury

New Member
Joined
Mar 3, 2010
Messages
3
Location
Savannah, GA
Okay, so I found the 'Rotary Wing Forum' and did a little more reading under "Laflame Tandem First Lift Off". Never heard of it, and I don't think anyone else has since 2005. (the thread started in 2004 and some of the folks here participated)
Yeah...there's a little more to the tandem flight dynamics and control then I thought. Possibly there can be room to simplify and mitigate some of the bad flight characteristics, maybe not.

I guess I should be over there and lurk around a bit before getting all excited.
Thanks
 

Unclematt

Well-Known Member
Joined
Mar 12, 2010
Messages
81
Location
Durango, CO
I bought plans out of a magazine many years ago for a single place micro-helo that used 2 small 2-stroke powered props mounted on the main blade. The small props drove the main blade , and the main blade provided lift/thrust. You controlled the whole thing by RC servos on the throttles, and a lever bar attached to the main hub. I was never brave enough to build it or fly it. I still have the plans around here somewhere...
 

joe nelson

Well-Known Member
Joined
Jan 9, 2008
Messages
265
Location
Cincinnati,Ohio
The concept that I'm working on is using servo flaps on a gyro rotor system. It is controlled with a swash plate that uses HMWP bearings and Hughes type strap pack. This configuration would allow a collective to be used making vertical take off and landings possible.

The problems, at first, was the blades being too flexible. After solving this problem I found that the 304 stainless straps were too weak for man-rated use. I'm now switching to another material maybe 4130. I normally test to 2x operating rpm but was only able to get 450 rrpm before material deformation at the drag hinge hole.
 
2
Top