ELIPPSE propeller for RVs

elippse · #1 06-14-2007, 01:14 PM

Many of you on this forum have expressed an interest in getting information on ELIPPSE-designed propellers. Well, wait no longer. Larry Morgan of Vari-Prop has produced a three-blade ground-adjustable or constant-speed propeller with ELIPPSE-designed blades for use on the RV-series from 150HP to 200 HP. The CS version uses an electro-hydraulic pitch-changing mechanism, so it is not necessary to have a drilled crankshaft. It will be on display at the Golden West fly-in at Yuba County airport at the end of June, 29, 30, and July 01, as well as at Oshkosh. The Vari-Prop web-site is still under construction, so for more information about this propeller, contact Larry Morgan at 503 804 5508, or lmorgan724@yahoo.com. For those of you in the Portland, OR area, you can see Larry at his hangar next door to Van's Aircraft.

rtry9a · #2 06-14-2007, 01:59 PM

Any performance data yet on an RV?

zav6a · #3 06-14-2007, 04:39 PM

Thanks Paul.. I'll look forward to it.

Bob Axsom · #4 06-14-2007, 09:01 PM

I know this going to yield a major jump in speed based on the Reno biplane class results.

Bob Axsom

rv620mr · #5 06-15-2007, 09:49 AM

Paul,

I just spoke with Larry Morgan via telephone.

Could you please share your thoughts about using the Vari-Prop hub with ELIPPSE blades on a parallel valve O-360 with a high compression ratio and electronic ignition?

I'm reasonably informed about prop vibration surveys, the varying dampening qualities of wood, carbon, aluminum, etc. So, while I welcome any input you may have, it's not my intention to burden you with a request for a treatise.

Thank you.

rvator51 · #6 06-15-2007, 10:12 AM

Larry says that they will be in Hanger C at booth 3109 (Contact Magazine booth).

elippse · #7 06-15-2007, 10:43 PM

Don't jump ahead, Roberto! Larry will do lots of before and after testing to see if there is a measurable performance increase to brag about. I'm hoping that the Reno experience is a harbinger of things to come, but let's wait and see. And Monte, I'm not at all familiar with this hub, but from what Larry tells me, it has seen lots of activity on airboats. Some of you are familiar with the somewhat different shape of my designs, and how the prop has a concave planform taper as it approaches the tip, where it goes to a point. It does not have most of the lift, not thrust, in the outer portions as in most props, but instead, as with an elliptical wing, it has an elliptical lift distribution which goes to zero at the tip, thus minimizing span-wise flow and tip vortex. Since the lift is distributed all along the blade as opposed to being mainly outboard, this should bring about rather benign bending forces at the hub. Another benefit of this taper is that the mass outboard is considerably reduced, thus greatly reducing centrifugal loading on the hub. Outboard mass reduction also helps when considering the inertial load when the prop is accelerated and decelerated on each power pulse; think of the whip at the tip of a fishing pole when casting. This minimizes the in-plane stresses where the blade emerges from the hub. I think that this is what is taking place on those blades which are having cracking problems from the big power pulses on these IO-360s. All told, I am hoping that this will not take its place among the many tales of recent CS and ground-adjustable hubs that seem to have these cracking problems. I'm not sure what this thing is about EIs being hard on CS props. LSE ignition has very precise timing on all cylinders, whereas a magneto has somewhat random small variations in timing around a mean. It could be that this very timing precision is able to excite the various resonances in some blades, whereas the magneto would throw off the periodicity somewhat, and so not produce as high an excitation amplitude. But that is really saying that the prop has resonances that are on the borderline of being properly damped. So far neither Tom on his biplane props nor I on my FP three-blade prop have seen any cracking in the hub region. Klaus is always tapping my prop with a coin in the region where the transition takes place from blade to hub. With my higher pitch angles there, in the 65-70 degree region, the transition angle is not as great as it is on the many props that have root pitch angles of about 45-50 degrees, so there is less twist to the laminate in going from the blade to the hub and so less chance of de-lamination. 'Hope this addressed some of your concerns! I hope there are many of you attending Reno this year. If you are, be sure to get a pit pass and come see the real world of Experimental Aviation, where it's taking place and not just being talked about. One of my prop designs will be on a Sport plane, two on F1s, and at least four on biplanes. Along with that, one of the racers will have my super-secret compact augmented cooling-exhaust system. As with my blade designs, when you see this you will have a hard time believing it can work! Just be aware, we have applied for a patent on it! And maybe by Oshkosh, Klaus will be able to show our new dual-redundant EFI. Two sets of drivers, two pressure-controlled pumps that require no return line to the tank. He has been flying this on his plane for three years now, as well as having raced it at Reno twice, and has wowed lots of pilots with its ease of starting on his hand-propped EZ, as well as how well it maintains A-F with change in altitude. As with the ignition, it's got lots of cool outputs that tell you pump pressure, MAP, and, both pulse and analog fuel flow. Every effort is being made to have a safe product. The control laws are in hardware, there is no software, so except for some minor circuit changes that may arise, there will be no software upgrades to implement from time-to-time.

zav6a · #8 11-03-2007, 07:21 AM

Did anyone get a peek at the augmented exhaust that Paul refers too. Paul, willing to share any details? Also interested in Klaus's FI system.

At Reno and saw some of the props! Watched some of the rebuild work going on on the worlds fastest biplane. Anybody know how he turned out this year?

pierre smith · #9 11-03-2007, 07:39 AM

...of the 2007 races are here:

http://www.airrace.org/2007ResultsDisplay.php

Regards,

RV6_flyer · #10 10-01-2010, 04:26 PM

http://www.eaa.org/experimenter/arti...09_phantom.asp

Copy / Paste from the above link:

"Monday, September 13 ? An excited voice on the other end of the phone said, ?Paul, it?s Tom. I qualified at over 260 mph.? That?s when I, too, started jumping up and down! Here?s this man, this pilot, Tom Aberle, telling me that his biplane Phantom, which back in 2003 qualified at 220 mph, had now bettered that by 40 mph. Unbelievable!"