Sport Copter Vortex 912ULS [Archive]

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Steven_Kozned

11-07-2003, 11:46 AM

Just a quick note to introduce myself and to thank you all for making this forum so interesting and useful.Is anyone out there flying or building a 912S powered gyro that could share building/flying advice?

MattPearson

11-07-2003, 01:09 PM

Steve, Jim advised you to learn a tail dragger plane or gyro?? Either way, did he say why?  Regardless of the engine (unless it's underpowered) any wise, informed, experienced gyronaut will tell you that if a gyro: 1.  is designed for CENTER LINE THRUST 2.  and has an adequate HORIZONTAL STABILIZER as aircraft go, is a piece of cake to learn and fly.  Of course everyone's ability to grasp a concept is a different, but a gyro set up as described is amazingly docile, gentle, predictable and a joy to fly.  Ask Jim about CENTER LINE THRUST and HORIZONTAL STABILIZERS and how his ships are designed and then let us know. I am curious.

MattPearson

11-07-2003, 11:59 PM

Steve, "Very docile" does not answer the question. The other problem is that if you visualize that everything in flight pretty much rotates around it's center of gravity, then adding a very powerful thrusting moment above the CofG is going to push the nose down creating a risk of POWER PUSH OVER. You will be at risk. Examine for yourself the following animation. http://webpages.charter.net/wartowne/Bunt.gif I believe this GIF courtesy of Al Hammer

GyroRon

11-08-2003, 02:12 AM

Sportcopter is not CLT but not very far off it. It also has a big Horizontal so I wouldn't be too scared! I would get some training in a not so stable gyro - I highly reccomend Steve McGowan - so you will build the reflex reaction to put that power and stick back when needed. I personally have not trained in a Stable gyro so I may be off base. But It is like getting flying lessons in a Cessna to go fly your Pitts special. A smart Pitts driver would get some time in a Pitts first

PW_Plack

11-08-2003, 04:35 AM

What's missed in this whole discussion is that CLT is a means to an end, not an end in itself. The object is pitch stability, and CLT makes that much easier, but an effective horizontal stab with a modest thrust offset also works. That said, there are no hard stability numbers available on the Vortex, nor on any other machine except the AAI Sparrowhawk. This is a problem the kit industry really needs to address, and the pressure brought through the forums will help. If you want to learn in a machine which mimics the habits of a Vortex, you could do worse than Jim's own trainer. If (CFI) Pat Warren's availability improves, or other instructors become available in the area, Jim's Vortex II two-place is built very much like the Vortex single, and now that it has a hopped-up Subaru and in-flight variable-pitch prop, it performs almost the same with two aboard as the single place with the Rotax 582. Reactions to control inputs will be more sluggish, but that's probably a good idea while you're training!

Terry_Smith

11-23-2003, 12:25 PM

Matt,   In regards to the RAF gif, I created the original one with the moving blades and flashing strobes, but Al might be the one who made the PPO version.  I created it originally when I first got interested in gyros and before I realised how poorly the original RAF was designed. Terry

Udi

11-24-2003, 02:56 AM

There were a few Sport Copter crashes, but I don't know of any that PIOed or PPOed.  Jim Vanek's apparent lack of theoretical understanding is not, by itself, an indication that his gyros are unstable. Steven, the only advice I can give you is to try and keep the gyro CG as high as you can.  Don't install heavy components, like the battery, very low.  Try and keep the prop thrust line as close as possible to the CG.  When you finish building, perform a double hang test to see where the CG is.  Let Jim test fly it before you do. The Vortex is a beautiful machine and is mechanically very sturdy.  We don't really know how stable it is because no one has tested it.  Maybe you will one day.  The Vortex engine is tilted a few degrees nose up.  This makes the thrust offset problem even worse, but I think this was done in order to immerse the stab in the prop wash and provide some nose up moment. Personally I feel that Vanek could sell many more machines if he were more open to the stability issue.  Air Command is a good example of a company that chose to evolve and adapt.  This is just good business. Udi

Gary_in_Orygun

11-24-2003, 03:05 AM

I'm curious to know why you think Jim V. has an "apparent lack of theoretical understanding".  I have talked with him a lot these last couple years and he is aware and understands all the issues and theories being bantered about.  But he has one more important addition to all the theories, and that is personally testing many of those theories to see where the tires meet the road (rotors meet the air).  There are areas where CLT is not the only consideration while handling and safety are still met.

Udi

11-24-2003, 08:24 AM

When a person is asked whether his gyro is CLT or not, and he answers that his machine is "docile", it shows either a lack of understanding of the basics, or maybe he is trying to avoid the question.   Ask Greg Gremminger whether his Magni is CLT, and you're going to get the whole 9 yards on how Magni achieved positive stability without being CLT. Note that I didn't say that the Vortex is unstable; I just said that Jim can't, or won't, tackle the subject.  I asked him the same question and I got a similar answer (to me he said that “all these people on the internet don’t know what they are talking about”).  So maybe his gyro is stable, but he does not have the theoretical knowledge to explain why.  Or if his gyro is not stable, he cannot explain why this is, in his opinion, not important. Udi

Aussie_Paul

11-24-2003, 06:03 PM

It will be good when the pitch stability tests are defined in the LSA standards. This will allow all manufacturers to use the same datum as to the pitch stability of their aircraft. Then the public can decide for themselves based on credible evidence. Aussie Paul.

Phillip

01-29-2004, 10:13 PM

Hello guys. I found this forum via the newsgroup.

My name is Phillip Williamson and I've known Jim Vanek since the mid 80's. I watched him design the Vortex (PRA Ch. 73 met at his hanger). I never caught the gyro "bug" but I do have shy of 1000 hours as a fixed-wing private pilot. That said...and having nothing but .75 hrs of gyro time, the Vortex seems very stable to me. I'd ask if stability has anything to do with this: The Vortex is the ONLY gyro I've seen do a loop or a roll. He'd fly it with his hands and feet hanging out the sides. Does that count? I'm asking because it seemed to be a pretty gutsy thing to do. Jim has done this over and over at air shows and out at the Scappoose Airport. I'd trust him with my life without a second thought.

Anyhow, just thought I'd toss my 2 cents worth as someone that has a little history with Jim, his Dad Chuck, and the Sportcopter/Vancraft company.

Safe flying
Phil

Doug Riley

01-30-2004, 12:31 PM

"Gutsiness," of course, has nothing to do with the stability of the machine. It's a personality trait of the pilot, not the hardware.

A number of gyro brands have been looped and/or rolled. Only one person attempting this has been killed, as far as I know. His fall to his death out of a loop in a VW-powered Bensen was reported many years ago in the PRA magazine.

Ken Brock's airshow demo routinely involved bank angles of more than 90 degrees. Roger Wood does a loop-roll-ish inverted maneuver. The old Cierva gyros were looped by Johnny Miller in his airshow routine.

Florida was home to a fellow who seemed to be the king of inverted gyro flight: he regularly looped and rolled his Bensen. He would loop or roll other gyros, as well. I don't recall his name, but his exploits were also reported (with photos) in the PRA mag. He died of natural causes several years ago.

All of these folks are/were flying their rotors with ordinary positive G loads. Photos of their gyros while inverted show the rotor blades to have their usual coning angle, indicating that the blades were carrying a load (not necessarily one G). These maneuvers, then, are the equivalent of swinging a pail of water over your head: get up adequate speed and the water stays put.

An unstable gyro will make it through a positive-G maneuver without difficulty, although the stick forces will be peculiar when the G's are above one (just as they are in a tight turn). If the gyro loses airspeed and falls out of the top of a loop, it's at great risk of zero- or sustained negative-G (airflow the wrong way through the blades), which is extremely hazardous, even in a stable machine.

The maneuver that will separate the killer machine from the non-killer machine is a low-G pushover, or flight through a downdraft, at wide-open throttle. Obviously, you should not test an unfamiliar machine for stability problems by duplicating such a maneuver. There are flight test procedures that can tease out instabilities in this area without exposing the pilot to deadly risk.

scott heger

03-21-2004, 02:10 PM

I think any of you that make a negative comment regarding a SportCopter without flying one, or Jim Vanek based on the report of a third party's comments are lacking alot of basic information. A Vortex kit, unmodified is a very forgiving machine under every condition I have flown it in. That includes full power zero starting speed pushover dives to 110 MPH turning into straight up vertical climbs back to Zero airspeed, and then doing a reverse backward tailslide terminating in a spinning flat decent. I know many machines can do all these things, but a SportCopter does them without any hint of unstability, including flying in very high gusty wind and landing conditions, and 50-60 mph sideways flight.
Jim V. sometimes does not do a good job of "sharing"some of his gyros' features . I believe this is because he does not really chooose share all of his own personal enginneering with every person that calls and asks questions about his machines. FRom a business standpoint, it may be questionable ,and leave some with the impression that he has a"vodoo" machine. I think he gets many calls from tire kickers trying to copy things he has done without paying, remember this is his livelyhood. As a customer, he has completely answered any question I have put to him regarding engine tilt, stabilizer issues, rotor design and performance, and flight envelope in great detail to my satisfaction. He probably wont share this with prospective buyers, and I understand that can turn people off. However if you have talked to him, and not gotten the answers you like, move on to another brand of machine, but for those of you that are really interested in buying a single seat high performance forgiving machine, give Jim a call and get ready for the most fun sport flying has to offer. I have not regretted the purchase of my Vortex in the 5 years that I have had it, and have been very pleased with the service I have received from him and his staff, well beyond the call.
I am interested to see how the 912 project works out, and the additional weight and power may show a fault that does not show in the lower powered/weight 2 strokes. I agree Jim should be the first to fly it, and I am sure he will. Remember, he has been flying gyros since his teens, and is a hands-on owner that flys every set of blades he makes.

Rotornut

03-24-2004, 02:27 PM

Florida was home to a fellow who seemed to be the king of inverted gyro flight: he regularly looped and rolled his Bensen. He would loop or roll other gyros, as well. I don't recall his name, but his exploits were also reported (with photos) in the PRA mag. He died of natural causes several years ago.

Doug, The gentlemans name is Carl Hendrix, his mom and him owned the Resturant in Lake Wales called the "Chalet Suzan", that Sunstate Rotor Club visited alot.

From all I hear he was a Great Pilot, very Daring!

MJ :)