---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Tue 12/30/03: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:00 AM - Re: MT Propeller Update (flyv35b) 2. 02:21 PM - Re: MT Propeller Update (Bruce Smith) 3. 03:53 PM - Re: TeamGrumman-List Digest: 2 Msgs - 12/29/03 (Tiger67B) ________________________________ Message 1 _____________________________________ Time: 08:00:48 AM PST US From: "flyv35b" Subject: Re: TeamGrumman-List: MT Propeller Update --> TeamGrumman-List message posted by: "flyv35b" > It climbs well, but the benefits of constant speed are lost in the 2500 rpm > red line imposed by the STC. And herein lies the key IMO, along with the cost and probability that the plane will be measureably slower than it is with the Sensenich prop, why the prop will not be very popular or sell well. For years Dick Van Grunsven and Van's Aircraft has been very interested in evaluating performance of the RV aircraft with various props. And considerable testing was done in conjunction with the CAFE 400 races back in 1990 with numerous wood props. More recently Van's Aircraft has evaluated performace with both fixed pitch and constant speed props and recently published the results in the "RV Aviator". The tests were conducted with a 180 hp RV-8 operating at "optimum cruise speed". That was defined as the speed attainable at 8000' altitude and 75% power (full throttle) and 2500 rpm. 2500 rpm because that, even though 2700 rpm is the rated rpm for the engine, most pilots would not be comfortable operating at 2700 rpm continuously for cruise operation. This criteria was chosen as the most important performance criteria for most pilots. Climb rates with the various CS prop varied by about 2-5%. All of the props tested (6 constant speed and one fixed pitch) were 2 blade except for a 3 blade Whirlwind and a 3 blade MT wood/composite, the configuration recommended by MT. The poorest performing prop was the 3 blade MT, which was 8.2 mph slower than the best prop, a new 2 blade Hartzell "blended airfoil", which resulted in 208.9 mph. The 3 blade Whirlwind prop (at 203 mph) was 3.7 mph slower than the 2 blade whirlwind prop. The 2 blade fixed pitch Sensenich prop resulted in a speed of 207.9 mph at 2500 rpm and 210.9 mph at 2700 rpm. This Sensenich prop was essentially designed for the RV aircraft and is quite similar to the 76" dia. one used on the Tiger. According to the article "conventional knowledge holds that, everything else being equal, adding prop blades with result in reduced performance". This has also been true with the 2 and 3 bladed props used on the IO-520 powered Bonanzas until recently when Hartzell introduced their new 3 blade "blended airfoil" prop for it. I recently bought one of these props for my Bonanza and it does perform quite well. The Scimitar blade tip design has allowed an increase of 2 in. diameter over the 3 blade McCauley and still reduce the noise level, resulting in better takeoff and climb performance. Hartzell told me that this prop was also slightly faster than the original 2 blade McCauley. And this is contrary to the conventional knowledge mentioned above thanks to Hartzell's ability to machine a blade with a continuous change in airfoil for optimum efficiency and noise reduction. I paid $7800, including the beautiful spinner assembly, for this 82 in. dia. prop and am very happy with it. *All of the comments made here pertaining to the test results, etc. were taken from an article written by Van in the most recent RV Aviator newsletter. Cliff A&P/IA ----- Original Message ----- From: Subject: TeamGrumman-List: MT Propeller Update > --> TeamGrumman-List message posted by: TeamGrumman@aol.com > > I talked to an FAA guy with experience certifying an MT prop on a Cherokee. > He told me they did the certification for 2700 rpm redline. > > He also suggested I look up the Type Certificate Data Sheet for the prop and > see if it spells out what the design red line is. > > So I did. > > But First... > > I flew the MT prop a couple more times. As I might have mentioned, the > controller is set to operate at 1500-2500 rpm. After flying the plane, at > anything much above 15 to 18 inches manifold pressure, the pop won't pull down to > 1500 rpm with the controller set to 1500 rpm. > > From the little experience I have flying the plane with the MT prop, it looks > like the engine operating range should be in the 1800 to 2700 rpm range. > Perhaps, to be perfectly honest, with a lot of flying time, I could see > justification for anything below 2000 rpm. As it is, even with the controller set to > 2500 rpm, flying a touch and go pattern is a piece-O-cake. I'm not clear as > to why anyone would need to set the engine to 1500 rpm. > > As for the TCDS redline. the prop looks like it's designed for 210-220 hp and > 2800 rpm. > > It climbs well, but the benefits of constant speed are lost in the 2500 rpm > red line imposed by the STC. > > Gary > > ________________________________ Message 2 _____________________________________ Time: 02:21:52 PM PST US From: Bruce Smith Subject: Re: TeamGrumman-List: MT Propeller Update tests=FROM_HAS_MIXED_NUMS, FROM_HAS_MIXED_NUMS3 --> TeamGrumman-List message posted by: Bruce Smith Cliff and all, New technology (or at least mid 80's tech since the blended airfoils and flaps on the trailing edges of the blades were really pioneered during the research conducted for the "propfans" developed by both GE and Hamilton Standard) are cool. However, they usually involve increased complexity. Therein lies the rub. The beauty of the Grummans is their performance AND simplicity. A fixed pitch prop isn't sexy, but it usually is reliable, and not prone to cause pilot error, ie. go around with the prop in high pitch. It gets the job done. So, while it's nice that someone is going the route of STC'ing the MT prop, where is the value for the $10K+? I agree with Gary, it looks cool. But, I've gotten 1000 fpm climb in the Tiger I rent, so where is the return on investment? If I had a couple of million dollars, I'd get with Gary and Bruce Catto and see if I could concoct a better (composite) fixed pitch prop. Till the lottery comes my way, I'm gonna rely on a good old Sensenich fixed pitch prop. Happy New Year to all!!!! Bruce Smith flyv35b wrote: >--> TeamGrumman-List message posted by: "flyv35b" > > > >>It climbs well, but the benefits of constant speed are lost in the 2500 >> >> >rpm > > >>red line imposed by the STC. >> >> > >And herein lies the key IMO, along with the cost and probability that the >plane will be measureably slower than it is with the Sensenich prop, why the >prop will not be very popular or sell well. > > > ________________________________ Message 3 _____________________________________ Time: 03:53:18 PM PST US From: Tiger67B Subject: TeamGrumman-List: Re: TeamGrumman-List Digest: 2 Msgs - 12/29/03 --> TeamGrumman-List message posted by: Tiger67B JUST IN CASE YOU DIDN'T SEE THIS...... AOPA ePilot Special Airspace Bulletin December 30, 2003 A special notice to AOPA members in and near southern Nevada ==> ATTENTION PILOTS <== FAA EXPECTED TO ESTABLISH TFR OVER LAS VEGAS AOPA is sending this message to advise you that airspace restrictions are expected over New Year's Eve celebrations in Las Vegas tomorrow, December 31. According to the FAA, the notam is expected to create a temporary flight restriction (TFR) within a 20-nm radius of McCarran International Airport, with an extension to the southeast around the Hoover Dam, from the surface to 18,000 feet msl. All pilots will be required to squawk a discrete transponder code and maintain two-way communication with ATC. There will also be a 6-nm-radius no-fly zone centered on the airport that prohibits all general aviation flight activities from the surface to 18,000 feet msl. The restrictions will be effective from 8 p.m. local time tomorrow, December 31 (New Year's Eve), until 3 a.m. local on Thursday, January 1 (New Year's Day). As of 3 p.m. Pacific time Tuesday, a notam establishing the TFR had not been issued. The full text of any notams implementing this anticipated airspace restriction will be posted on AOPA Online as soon as possible after they are issued ( http://www.aopa.org/whatsnew/notams.html ). "Security-related TFRs usually single out general aviation aircraft, which have never been used in a terrorist attack," said AOPA President Phil Boyer. "The restrictions are an additional burden for pilots to carry. AOPA believes they should only be issued based on credible threats--not for a political need to be seen taking strong measures." Because TFR airspace frequently changes, AOPA strongly encourages pilots to obtain a briefing and CHECK NOTAMS before every flight. TFR violators will be intercepted and forced to land. ==> HELPFUL WEB LINKS <== AOPA's Real-Time Flight Planner provides up-to-the-minute graphical depictions of TFRs ( http://www.aopa.org/flight_planner/ ). Check the FAA's TFR Web site ( http://tfr.faa.gov ). Download the AOPA Air Safety Foundation's intercept procedures card ( http://download.aopa.org/epilot/2003/intercept.pdf )or review ASF's "Know Before You Go" program ( http://www.aopa.org/asf/know_before/ ).