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richard.goode(at)russiana
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 Posted: Mon Oct 26, 2009 10:04 am Post subject: GT propeller blades on V530 hubs |
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I am disappointed by the lack of objectivity in Rick Volker's posting. Before anything else, and before I am accused of bias, could I make the following clear.
- I am a MT agent and sell a large number of MT propellers for a variety of applications.
- In Europe we have a significant problem of propellers, since MT, while excellent are expensive, and we can ONLY use certificated propellers. With ground strikes; old age etc we are running out of blades for our V-530s, and there simply are no other substitutes we can use.
- I have been a keen supporter of GT Propellers, and indeed am currently assisting them to get full European certification with EASA (our overall aviation controlling body)
- I have always been concerned about the safety of propellers. Some years ago I had a major failure on a propeller (not V-530/MT!) which was very nearly disastrous, and this is a fundamental reason why I am very careful about the propellers behind which I will fly, and which propellers I will recommend. There have been a number of high-profile propeller failures of non-certificated props, and, in my view, until a propeller has been properly tested AND certificated, I believe that any purchaser should tread very carefully.
To deal with the statistical evidence, I re-emphasise that I am very keen for the GT propellers to perform well against the more established props. Having said that I have been involved in extensive propeller trials, and I have concerns about the following issues:
- Ricks figures are a single figure for each propeller and each perameter. For properly objective tests you need to run each perameter at least three times.
- they are not mentioned so possibly he did them, but I doubt if there were proper corrections for temperature and pressure changes, which make a huge difference to these things. I am very aware of how long it takes to contact these tests, and things can change quite rapidly, particularly during the time that it takes to change from one propeller to another.
- Aircraft weights need to be exactly identical - it is all too easy to contact one test; fly again, without precisely filling fuel and oil to the same level.
- Rick refers to "more static thrust" - I do not see any figures, so wonder whether these were properly measured.
- Rick refers to "dynamically balanced", but clearly these props are being removed and put back on again, in which case the dynamic balance will certainly be lost. IF these propellers were not being immediately put on, then how long and over what period were the tests being conducted, and certainly if time has been taken to re-dynamically balance each propeller, then there must have been climatic changes.
- It is also slightly misleading to refer to the MTV3 propeller - this is an old design, long out of production, and only likely to be available second hand.
- For pricing, Rick is somewhat misleading to suggest that the GT propeller is half the price of MT. He gives a price of US $8,428, but this is only for two GT propeller blades. The current list price for a complete MTV-9-250 or 260 is US $15,600. This is of course for a factory new propeller, absolutely complete, whereas the GT price of US $8,428 is simply for two blades, so you then need to get a hub; overhaul it; install the blades; balance etc.
So to conclude, I am very much a supporter of GT propeller, and I am hoping that we are able to obtain full certification for their blades. BUT any performance / cost comparisons between propellers MUST be done scientifically and objectively!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
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rick(at)rvairshows.com
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| Posted: Mon Oct 26, 2009 6:18 pm Post subject: GT propeller blades on V530 hubs |
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In reading my original prop comparison post, you will notice my "for more information, contact:". I chose not to display all information due to quantity, hoping any interested parties would contact me for the details. Let me fill you in:
On September 11,2009 at KIAG airport;
Flight one-1300 local time: MTV3. SU26M, full fuel. Density altitude 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight two-1430 local time: V530. SU26M, full fuel. Density altitude unchanged at 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight three-1630 local time: GT 250 cm blades on V530 hub. SU26M, full fuel. Density altitude 774'. Each test repeated three times during 25 minute flight with test average noted.
On September 15,2009 at KIAG airport:
Flight one-1130 local time:MTV9. SU26M, full fuel. Density altitude 1037'. Altitude for tests changed to adjust for different density altitude. Each test repeated three times during 25 minute flight with test average noted.
Note;
-Aircraft weight was identical for each flight. Oil and fuel were exactly the same. The Profile for each flight was identical so that the weight of the aircraft would be identical for each part of the flight compared. Weather data can be confirmed via online sources.
-Static thrust was not directly measured, however stall speed tests under full power with this weight aircraft allowed gross comparisons of relative thrust at close to zero airspeed. Differences between aircraft were marked and statistically significant.
-The MTV9 was dynamic balanced on this aircraft before flight. Other props were not. I agree that dynamic balance performed on other aircraft are next to useless. Dynamic balance of V530 prop is more difficult on Yak 52 because of the proximity of blade to the ground allowing buffeting to limit ground run rpm and the lack of a spinner backplate for fine tuning.
The purpose of my post was to alert Yak 52 owners to a good alternative to MT if the original V530 blades must be replaced or if performance enhancements are desired. The price is not so expensive if you already have a good V530 hub. The MTV3 and MTV9-260-29 were owned by me and do not represent all of the choices in selecting a new MT prop.
My experience with MT has been mixed. A new MTV9-260-29 prop was so rough in flight that MT eventually sent me a new set of blades that corrected the problem, after 3 dynamic balance attempts with 2 complete tear-downs/inspections in between. But this all took one year. They do not yet know what was wrong with the original new blades. I had to find other props to get me through my air show season. MT did not have a loaner. I had a spare MTV3. GT Propellers also offered to loan me their blades for a spare V530 hub that I owned. A friend with a Yak 52 offered me a 20 hr TT V530. I compared them out of curiosity. It would have been much better to have an MTV9 of the proper length and type blade design with a Yak 52 to compare. The MTV3 has been around and many M14P pilots are familiar with them. The MTV9-260-29 is an airshow-only prop that is not suited for 90% of the types of flying done by Yak 52 pilots. I am satisfied with my MTV9-260-29 for my application. It allows me to do things that can not be done with any other prop. But you pay a price for this extreme. The high static thrust comes with a loss of max and cruise speeds. It also gives a crazy power off glide ratio that makes for some exciting air show antics. A well known MT dealer promised that his tests showed the MTV9-260-29 prop did everything well. Imagine that.
I was so impressed by the performance of the GT prop when compared with the original V530 blades, that I suggested to GT that I would sell them in the US. They have built a prop using the same construction techniques for a Spitfire Mk IX with 1700hp. The GT blades allow the Spitfire to remove manifold pressure limitations of all past designs and have been pull tested to prove their strength. This suggests that GT has the know how to build a prop that is strong enough for the M14P application. I hope that certification is achieved soon as scientifically done performance testing has been very convincing in GT's favor. I will look forward to seeing more testing done by others to compare the GT 250cm with the current MTV9 model offered for Yak52 V530 replacement.
Rick Volker
On Oct 26, 2009, at 2:03 PM, Richard Goode wrote:
| Quote: | I am disappointed by the lack of objectivity in Rick Volker's posting. Before anything else, and before I am accused of bias, could I make the following clear.
- I am a MT agent and sell a large number of MT propellers for a variety of applications.
- In Europe we have a significant problem of propellers, since MT, while excellent are expensive, and we can ONLY use certificated propellers. With ground strikes; old age etc we are running out of blades for our V-530s, and there simply are no other substitutes we can use.
- I have been a keen supporter of GT Propellers, and indeed am currently assisting them to get full European certification with EASA (our overall aviation controlling body)
- I have always been concerned about the safety of propellers. Some years ago I had a major failure on a propeller (not V-530/MT!) which was very nearly disastrous, and this is a fundamental reason why I am very careful about the propellers behind which I will fly, and which propellers I will recommend. There have been a number of high-profile propeller failures of non-certificated props, and, in my view, until a propeller has been properly tested AND certificated, I believe that any purchaser should tread very carefully.
To deal with the statistical evidence, I re-emphasise that I am very keen for the GT propellers to perform well against the more established props. Having said that I have been involved in extensive propeller trials, and I have concerns about the following issues:
- Ricks figures are a single figure for each propeller and each perameter. For properly objective tests you need to run each perameter at least three times.
- they are not mentioned so possibly he did them, but I doubt if there were proper corrections for temperature and pressure changes, which make a huge difference to these things. I am very aware of how long it takes to contact these tests, and things can change quite rapidly, particularly during the time that it takes to change from one propeller to another.
- Aircraft weights need to be exactly identical - it is all too easy to contact one test; fly again, without precisely filling fuel and oil to the same level.
- Rick refers to "more static thrust" - I do not see any figures, so wonder whether these were properly measured.
- Rick refers to "dynamically balanced", but clearly these props are being removed and put back on again, in which case the dynamic balance will certainly be lost. IF these propellers were not being immediately put on, then how long and over what period were the tests being conducted, and certainly if time has been taken to re-dynamically balance each propeller, then there must have been climatic changes.
- It is also slightly misleading to refer to the MTV3 propeller - this is an old design, long out of production, and only likely to be available second hand.
- For pricing, Rick is somewhat misleading to suggest that the GT propeller is half the price of MT. He gives a price of US $8,428, but this is only for two GT propeller blades. The current list price for a complete MTV-9-250 or 260 is US $15,600. This is of course for a factory new propeller, absolutely complete, whereas the GT price of US $8,428 is simply for two blades, so you then need to get a hub; overhaul it; install the blades; balance etc.
So to conclude, I am very much a supporter of GT propeller, and I am hoping that we are able to obtain full certification for their blades. BUT any performance / cost comparisons between propellers MUST be done scientifically and objectively!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
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radiopicture
Joined: 23 Jun 2008
Posts: 263
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| Posted: Mon Oct 26, 2009 6:38 pm Post subject: GT propeller blades on V530 hubs |
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Good answer...
On Oct 26, 2009, at 10:16 PM, Rick VOLKER wrote:
[quote] In reading my original prop comparison post, you will notice my "for more information, contact:". I chose not to display all information due to quantity, hoping any interested parties would contact me for the details. Let me fill you in:
On September 11,2009 at KIAG airport;
Flight one-1300 local time: MTV3. SU26M, full fuel. Density altitude 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight two-1430 local time: V530. SU26M, full fuel. Density altitude unchanged at 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight three-1630 local time: GT 250 cm blades on V530 hub. SU26M, full fuel. Density altitude 774'. Each test repeated three times during 25 minute flight with test average noted.
On September 15,2009 at KIAG airport:
Flight one-1130 local time:MTV9. SU26M, full fuel. Density altitude 1037'. Altitude for tests changed to adjust for different density altitude. Each test repeated three times during 25 minute flight with test average noted.
Note;
-Aircraft weight was identical for each flight. Oil and fuel were exactly the same. The Profile for each flight was identical so that the weight of the aircraft would be identical for each part of the flight compared. Weather data can be confirmed via online sources.
-Static thrust was not directly measured, however stall speed tests under full power with this weight aircraft allowed gross comparisons of relative thrust at close to zero airspeed. Differences between aircraft were marked and statistically significant.
-The MTV9 was dynamic balanced on this aircraft before flight. Other props were not. I agree that dynamic balance performed on other aircraft are next to useless. Dynamic balance of V530 prop is more difficult on Yak 52 because of the proximity of blade to the ground allowing buffeting to limit ground run rpm and the lack of a spinner backplate for fine tuning.
The purpose of my post was to alert Yak 52 owners to a good alternative to MT if the original V530 blades must be replaced or if performance enhancements are desired. The price is not so expensive if you already have a good V530 hub. The MTV3 and MTV9-260-29 were owned by me and do not represent all of the choices in selecting a new MT prop.
My experience with MT has been mixed. A new MTV9-260-29 prop was so rough in flight that MT eventually sent me a new set of blades that corrected the problem, after 3 dynamic balance attempts with 2 complete tear-downs/inspections in between. But this all took one year. They do not yet know what was wrong with the original new blades. I had to find other props to get me through my air show season. MT did not have a loaner. I had a spare MTV3. GT Propellers also offered to loan me their blades for a spare V530 hub that I owned. A friend with a Yak 52 offered me a 20 hr TT V530. I compared them out of curiosity. It would have been much better to have an MTV9 of the proper length and type blade design with a Yak 52 to compare. The MTV3 has been around and many M14P pilots are familiar with them. The MTV9-260-29 is an airshow-only prop that is not suited for 90% of the types of flying done by Yak 52 pilots. I am satisfied with my MTV9-260-29 for my application. It allows me to do things that can not be done with any other prop. But you pay a price for this extreme. The high static thrust comes with a loss of max and cruise speeds. It also gives a crazy power off glide ratio that makes for some exciting air show antics. A well known MT dealer promised that his tests showed the MTV9-260-29 prop did everything well. Imagine that.
I was so impressed by the performance of the GT prop when compared with the original V530 blades, that I suggested to GT that I would sell them in the US. They have built a prop using the same construction techniques for a Spitfire Mk IX with 1700hp. The GT blades allow the Spitfire to remove manifold pressure limitations of all past designs and have been pull tested to prove their strength. This suggests that GT has the know how to build a prop that is strong enough for the M14P application. I hope that certification is achieved soon as scientifically done performance testing has been very convincing in GT's favor. I will look forward to seeing more testing done by others to compare the GT 250cm with the current MTV9 model offered for Yak52 V530 replacement.
Rick Volker
On Oct 26, 2009, at 2:03 PM, Richard Goode wrote:
| Quote: | I am disappointed by the lack of objectivity in Rick Volker's posting. Before anything else, and before I am accused of bias, could I make the following clear.
- I am a MT agent and sell a large number of MT propellers for a variety of applications.
- In Europe we have a significant problem of propellers, since MT, while excellent are expensive, and we can ONLY use certificated propellers. With ground strikes; old age etc we are running out of blades for our V-530s, and there simply are no other substitutes we can use.
- I have been a keen supporter of GT Propellers, and indeed am currently assisting them to get full European certification with EASA (our overall aviation controlling body)
- I have always been concerned about the safety of propellers. Some years ago I had a major failure on a propeller (not V-530/MT!) which was very nearly disastrous, and this is a fundamental reason why I am very careful about the propellers behind which I will fly, and which propellers I will recommend. There have been a number of high-profile propeller failures of non-certificated props, and, in my view, until a propeller has been properly tested AND certificated, I believe that any purchaser should tread very carefully.
To deal with the statistical evidence, I re-emphasise that I am very keen for the GT propellers to perform well against the more established props. Having said that I have been involved in extensive propeller trials, and I have concerns about the following issues:
- Ricks figures are a single figure for each propeller and each perameter. For properly objective tests you need to run each perameter at least three times.
- they are not mentioned so possibly he did them, but I doubt if there were proper corrections for temperature and pressure changes, which make a huge difference to these things. I am very aware of how long it takes to contact these tests, and things can change quite rapidly, particularly during the time that it takes to change from one propeller to another.
- Aircraft weights need to be exactly identical - it is all too easy to contact one test; fly again, without precisely filling fuel and oil to the same level.
- Rick refers to "more static thrust" - I do not see any figures, so wonder whether these were properly measured.
- Rick refers to "dynamically balanced", but clearly these props are being removed and put back on again, in which case the dynamic balance will certainly be lost. IF these propellers were not being immediately put on, then how long and over what period were the tests being conducted, and certainly if time has been taken to re-dynamically balance each propeller, then there must have been climatic changes.
- It is also slightly misleading to refer to the MTV3 propeller - this is an old design, long out of production, and only likely to be available second hand.
- For pricing, Rick is somewhat misleading to suggest that the GT propeller is half the price of MT. He gives a price of US $8,428, but this is only for two GT propeller blades. The current list price for a complete MTV-9-250 or 260 is US $15,600. This is of course for a factory new propeller, absolutely complete, whereas the GT price of US $8,428 is simply for two blades, so you then need to get a hub; overhaul it; install the blades; balance etc.
So to conclude, I am very much a supporter of GT propeller, and I am hoping that we are able to obtain full certification for their blades. BUT any performance / cost comparisons between propellers MUST be done scientifically and objectively!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
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kjkimball(at)aol.com
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| Posted: Mon Oct 26, 2009 6:54 pm Post subject: GT propeller blades on V530 hubs |
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Rick,
The tests we made on the model 12 with 360hp M14P are as follows:
V530 static thrust 1320 lb (weight is 10lb more that all MT prop with spinner V530 no spinner)
MTV9-250-27 1500 lb thrust
MTV9-250-29 1575 lb thrust
MTV9-260-29 1525 lb static thrust
M14PF 400hp
MTV9-260-29 1800 to 1825 depending on engine/conditions
Barrett modified M14P to 400+ hp and fuel injection
MTV9-260-29 1825-1850 lb on 3 engines thus far
V530 the slowest overall at given power settings up to and including full throttle level flight. 260 about 5 mph slower than 250 MT prop on a 360 hp engine. A 260-29 on a BPE equipped model 12 was right at 10mph faster than a 360hp 250-29 model 12 at wide open. The BPE with 260 prop airplane burned about 4 less gallons of gas during a 30 minute flight than the stock 360hp/250 prop model 12.
V530 with it's square planform beat the living $h?t out of the fabric on the wings of the model 12 like it does to the tail on Yaks. The MT does not and this is a consideration as the a recover cost for a model 12 is in the $50k + range and up as the paint schemes become more and more complicated. We found on a few V530 props we have been around that the blades tended to wonder on pitch accuracy between the 2 blades. I don't know if this is from the blades or from the pitch control stuff inside. But, it added to the shake and if this is an issue with the 530 prop hub/system, the problem will most likely remain with the GT blades installed. Maybe the ones around this part of the country were not set up properly or were crap units. Just our experience.
For the model 12, the 530 or 530 with WW or GT blades in it is less desirable due to the lesser overall acro and speed performance shown, lack of an attractive spinner, out of production, and heavier than the MT series.
Sincerely,
Kevin Kimball, Vice President
Jim Kimball Enterprises, Inc.
PO Box 849
5354 Cemetery Road
Zellwood, FL 32798-0849
407.889.3451 phone
407.889.7168 fax
www.pittsmodel12.com
www.jimkimballenterprises.com
Email: Kevin(at)jimkimballenterprises.com (Kevin(at)jimkimballenterprises.com)
On Oct 26, 2009, at 10:16 PM, Rick VOLKER wrote:
| Quote: | In reading my original prop comparison post, you will notice my "for more information, contact:". I chose not to display all information due to quantity, hoping any interested parties would contact me for the details. Let me fill you in:
On September 11,2009 at KIAG airport;
Flight one-1300 local time: MTV3. SU26M, full fuel. Density altitude 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight two-1430 local time: V530. SU26M, full fuel. Density altitude unchanged at 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight three-1630 local time: GT 250 cm blades on V530 hub. SU26M, full fuel. Density altitude 774'. Each test repeated three times during 25 minute flight with test average noted.
On September 15,2009 at KIAG airport:
Flight one-1130 local time:MTV9. SU26M, full fuel. Density altitude 1037'. Altitude for tests changed to adjust for different density altitude. Each test repeated three times during 25 minute flight with test average noted.
Note;
-Aircraft weight was identical for each flight. Oil and fuel were exactly the same. The Profile for each flight was identical so that the weight of the aircraft would be identical for each part of the flight compared. Weather data can be confirmed via online sources.
-Static thrust was not directly measured, however stall speed tests under full power with this weight aircraft allowed gross comparisons of relative thrust at close to zero airspeed. Differences between aircraft were marked and statistically significant.
-The MTV9 was dynamic balanced on this aircraft before flight. Other props were not. I agree that dynamic balance performed on other aircraft are next to useless. Dynamic balance of V530 prop is more difficult on Yak 52 because of the proximity of blade to the ground allowing buffeting to limit ground run rpm and the lack of a spinner backplate for fine tuning.
The purpose of my post was to alert Yak 52 owners to a good alternative to MT if the original V530 blades must be replaced or if performance enhancements are desired. The price is not so expensive if you already have a good V530 hub. The MTV3 and MTV9-260-29 were owned by me and do not represent all of the choices in selecting a new MT prop.
My experience with MT has been mixed. A new MTV9-260-29 prop was so rough in flight that MT eventually sent me a new set of blades that corrected the problem, after 3 dynamic balance attempts with 2 complete tear-downs/inspections in between. But this all took one year. They do not yet know what was wrong with the original new blades. I had to find other props to get me through my air show season. MT did not have a loaner. I had a spare MTV3. GT Propellers also offered to loan me their blades for a spare V530 hub that I owned. A friend with a Yak 52 offered me a 20 hr TT V530. I compared them out of curiosity. It would have been much better to have an MTV9 of the proper length and type blade design with a Yak 52 to compare. The MTV3 has been around and many M14P pilots are familiar with them. The MTV9-260-29 is an airshow-only prop that is not suited for 90% of the types of flying done by Yak 52 pilots. I am satisfied with my MTV9-260-29 for my application. It allows me to do things that can not be done with any other prop. But you pay a price for this extreme. The high static thrust comes with a loss of max and cruise speeds. It also gives a crazy power off glide ratio that makes for some exciting air show antics. A well known MT dealer promised that his tests showed the MTV9-260-29 prop did everything well. Imagine that.
I was so impressed by the performance of the GT prop when compared with the original V530 blades, that I suggested to GT that I would sell them in the US. They have built a prop using the same construction techniques for a Spitfire Mk IX with 1700hp. The GT blades allow the Spitfire to remove manifold pressure limitations of all past designs and have been pull tested to prove their strength. This suggests that GT has the know how to build a prop that is strong enough for the M14P application. I hope that certification is achieved soon as scientifically done performance testing has been very convincing in GT's favor. I will look forward to seeing more testing done by others to compare the GT 250cm with the current MTV9 model offered for Yak52 V530 replacement.
Rick Volker
On Oct 26, 2009, at 2:03 PM, Richard Goode wrote:
| Quote: | I am disappointed by the lack of objectivity in Rick Volker's posting. Before anything else, and before I am accused of bias, could I make the following clear.
- I am a MT agent and sell a large number of MT propellers for a variety of applications.
- In Europe we have a significant problem of propellers, since MT, while excellent are expensive, and we can ONLY use certificated propellers. With ground strikes; old age etc we are running out of blades for our V-530s, and there simply are no other substitutes we can use.
- I have been a keen supporter of GT Propellers, and indeed am currently assisting them to get full European certification with EASA (our overall aviation controlling body)
- I have always been concerned about the safety of propellers. Some years ago I had a major failure on a propeller (not V-530/MT!) which was very nearly disastrous, and this is a fundamental reason why I am very careful about the propellers behind which I will fly, and which propellers I will recommend. There have been a number of high-profile propeller failures of non-certificated props, and, in my view, until a propeller has been properly tested AND certificated, I believe that any purchaser should tread very carefully.
To deal with the statistical evidence, I re-emphasise that I am very keen for the GT propellers to perform well against the more established props. Having said that I have been involved in extensive propeller trials, and I have concerns about the following issues:
- Ricks figures are a single figure for each propeller and each perameter. For properly objective tests you need to run each perameter at least three times.
- they are not mentioned so possibly he did them, but I doubt if there were proper corrections for temperature and pressure changes, which make a huge difference to these things. I am very aware of how long it takes to contact these tests, and things can change quite rapidly, particularly during the time that it takes to change from one propeller to another.
- Aircraft weights need to be exactly identical - it is all too easy to contact one test; fly again, without precisely filling fuel and oil to the same level.
- Rick refers to "more static thrust" - I do not see any figures, so wonder whether these were properly measured.
- Rick refers to "dynamically balanced", but clearly these props are being removed and put back on again, in which case the dynamic balance will certainly be lost. IF these propellers were not being immediately put on, then how long and over what period were the tests being conducted, and certainly if time has been taken to re-dynamically balance each propeller, then there must have been climatic changes.
- It is also slightly misleading to refer to the MTV3 propeller - this is an old design, long out of production, and only likely to be available second hand.
- For pricing, Rick is somewhat misleading to suggest that the GT propeller is half the price of MT. He gives a price of US $8,428, but this is only for two GT propeller blades. The current list price for a complete MTV-9-250 or 260 is US $15,600. This is of course for a factory new propeller, absolutely complete, whereas the GT price of US $8,428 is simply for two blades, so you then need to get a hub; overhaul it; install the blades; balance etc.
So to conclude, I am very much a supporter of GT propeller, and I am hoping that we are able to obtain full certification for their blades. BUT any performance / cost comparisons between propellers MUST be done scientifically and objectively!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
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kjkimball(at)aol.com
Guest
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| Posted: Mon Oct 26, 2009 7:01 pm Post subject: GT propeller blades on V530 hubs |
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Rick,
A follow up question or two.
Which prop do you chose to fly on your Sukhoi and why? What are the most important factors for you in prop selection for your M14P powered airplanes?
For us as used on the model 12, the key selection factors are:
Availability new, service, spinner choice, colors, appearance and most important, overall performance on our airplane.
Sincerely,
Kevin Kimball, Vice President
Jim Kimball Enterprises, Inc.
PO Box 849
5354 Cemetery Road
Zellwood, FL 32798-0849
407.889.3451 phone
407.889.7168 fax
www.pittsmodel12.com
www.jimkimballenterprises.com
Email: Kevin(at)jimkimballenterprises.com (Kevin(at)jimkimballenterprises.com)
On Oct 26, 2009, at 10:16 PM, Rick VOLKER wrote:
| Quote: | In reading my original prop comparison post, you will notice my "for more information, contact:". I chose not to display all information due to quantity, hoping any interested parties would contact me for the details. Let me fill you in:
On September 11,2009 at KIAG airport;
Flight one-1300 local time: MTV3. SU26M, full fuel. Density altitude 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight two-1430 local time: V530. SU26M, full fuel. Density altitude unchanged at 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight three-1630 local time: GT 250 cm blades on V530 hub. SU26M, full fuel. Density altitude 774'. Each test repeated three times during 25 minute flight with test average noted.
On September 15,2009 at KIAG airport:
Flight one-1130 local time:MTV9. SU26M, full fuel. Density altitude 1037'. Altitude for tests changed to adjust for different density altitude. Each test repeated three times during 25 minute flight with test average noted.
Note;
-Aircraft weight was identical for each flight. Oil and fuel were exactly the same. The Profile for each flight was identical so that the weight of the aircraft would be identical for each part of the flight compared. Weather data can be confirmed via online sources.
-Static thrust was not directly measured, however stall speed tests under full power with this weight aircraft allowed gross comparisons of relative thrust at close to zero airspeed. Differences between aircraft were marked and statistically significant.
-The MTV9 was dynamic balanced on this aircraft before flight. Other props were not. I agree that dynamic balance performed on other aircraft are next to useless. Dynamic balance of V530 prop is more difficult on Yak 52 because of the proximity of blade to the ground allowing buffeting to limit ground run rpm and the lack of a spinner backplate for fine tuning.
The purpose of my post was to alert Yak 52 owners to a good alternative to MT if the original V530 blades must be replaced or if performance enhancements are desired. The price is not so expensive if you already have a good V530 hub. The MTV3 and MTV9-260-29 were owned by me and do not represent all of the choices in selecting a new MT prop.
My experience with MT has been mixed. A new MTV9-260-29 prop was so rough in flight that MT eventually sent me a new set of blades that corrected the problem, after 3 dynamic balance attempts with 2 complete tear-downs/inspections in between. But this all took one year. They do not yet know what was wrong with the original new blades. I had to find other props to get me through my air show season. MT did not have a loaner. I had a spare MTV3. GT Propellers also offered to loan me their blades for a spare V530 hub that I owned. A friend with a Yak 52 offered me a 20 hr TT V530. I compared them out of curiosity. It would have been much better to have an MTV9 of the proper length and type blade design with a Yak 52 to compare. The MTV3 has been around and many M14P pilots are familiar with them. The MTV9-260-29 is an airshow-only prop that is not suited for 90% of the types of flying done by Yak 52 pilots. I am satisfied with my MTV9-260-29 for my application. It allows me to do things that can not be done with any other prop. But you pay a price for this extreme. The high static thrust comes with a loss of max and cruise speeds. It also gives a crazy power off glide ratio that makes for some exciting air show antics. A well known MT dealer promised that his tests showed the MTV9-260-29 prop did everything well. Imagine that.
I was so impressed by the performance of the GT prop when compared with the original V530 blades, that I suggested to GT that I would sell them in the US. They have built a prop using the same construction techniques for a Spitfire Mk IX with 1700hp. The GT blades allow the Spitfire to remove manifold pressure limitations of all past designs and have been pull tested to prove their strength. This suggests that GT has the know how to build a prop that is strong enough for the M14P application. I hope that certification is achieved soon as scientifically done performance testing has been very convincing in GT's favor. I will look forward to seeing more testing done by others to compare the GT 250cm with the current MTV9 model offered for Yak52 V530 replacement.
Rick Volker
On Oct 26, 2009, at 2:03 PM, Richard Goode wrote:
| Quote: | I am disappointed by the lack of objectivity in Rick Volker's posting. Before anything else, and before I am accused of bias, could I make the following clear.
- I am a MT agent and sell a large number of MT propellers for a variety of applications.
- In Europe we have a significant problem of propellers, since MT, while excellent are expensive, and we can ONLY use certificated propellers. With ground strikes; old age etc we are running out of blades for our V-530s, and there simply are no other substitutes we can use.
- I have been a keen supporter of GT Propellers, and indeed am currently assisting them to get full European certification with EASA (our overall aviation controlling body)
- I have always been concerned about the safety of propellers. Some years ago I had a major failure on a propeller (not V-530/MT!) which was very nearly disastrous, and this is a fundamental reason why I am very careful about the propellers behind which I will fly, and which propellers I will recommend. There have been a number of high-profile propeller failures of non-certificated props, and, in my view, until a propeller has been properly tested AND certificated, I believe that any purchaser should tread very carefully.
To deal with the statistical evidence, I re-emphasise that I am very keen for the GT propellers to perform well against the more established props. Having said that I have been involved in extensive propeller trials, and I have concerns about the following issues:
- Ricks figures are a single figure for each propeller and each perameter. For properly objective tests you need to run each perameter at least three times.
- they are not mentioned so possibly he did them, but I doubt if there were proper corrections for temperature and pressure changes, which make a huge difference to these things. I am very aware of how long it takes to contact these tests, and things can change quite rapidly, particularly during the time that it takes to change from one propeller to another.
- Aircraft weights need to be exactly identical - it is all too easy to contact one test; fly again, without precisely filling fuel and oil to the same level.
- Rick refers to "more static thrust" - I do not see any figures, so wonder whether these were properly measured.
- Rick refers to "dynamically balanced", but clearly these props are being removed and put back on again, in which case the dynamic balance will certainly be lost. IF these propellers were not being immediately put on, then how long and over what period were the tests being conducted, and certainly if time has been taken to re-dynamically balance each propeller, then there must have been climatic changes.
- It is also slightly misleading to refer to the MTV3 propeller - this is an old design, long out of production, and only likely to be available second hand.
- For pricing, Rick is somewhat misleading to suggest that the GT propeller is half the price of MT. He gives a price of US $8,428, but this is only for two GT propeller blades. The current list price for a complete MTV-9-250 or 260 is US $15,600. This is of course for a factory new propeller, absolutely complete, whereas the GT price of US $8,428 is simply for two blades, so you then need to get a hub; overhaul it; install the blades; balance etc.
So to conclude, I am very much a supporter of GT propeller, and I am hoping that we are able to obtain full certification for their blades. BUT any performance / cost comparisons between propellers MUST be done scientifically and objectively!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
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rick(at)rvairshows.com
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| Posted: Wed Oct 28, 2009 6:57 am Post subject: GT propeller blades on V530 hubs |
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Kevin,
I choose to fly with an MTV9-260-29 prop on my SU26M. It has more low end thrust, better climb rate, more vertical penetration, and more time on vertical than the other props currently available. Aircraft behavior during gyroscopic maneuvers such as snap rolls, lomcevaks, flat spins, mulleroids, knife edge spins, etc. is dampened and more predictable than with other props I have tried. This allows more consistency and hence a lower safe altitude for the same maneuvers. The lower power-on stall speed gifted by the static thrust is only part of the reason for this. It is joined by an increased braking effect. The decreased speed of this prop gives me more time on downlines. I do not like the braking effect during the landing phase. In the power-off, opposite-the-numbers-on-downwind type of curving approach, most props give a user friendly glide angle. The MTV9-260-29, even when rpm is pulled back to 70%, requires a trickle of power. There is no brief glide at 1 inch above the runway. It becomes more of a short field spot landing. I like the MT large spinner for enhanced CHT cooling and appearance. I believe the stresses on the airframe and crankshaft during extreme gyroscopic maneuvers are lower with a 3 blade prop than with a 2 blade prop. MT has the only proven track record in Unlimited aircraft with M14P engines. The GT prop is about 10 pounds heavier than the MTV9. This gives the impression of creating higher gyroscopic forces on the aircraft. Snaps are snappier. Tumbles seem to explode and last longer. This is great fun! But this, again, adds more stress on the airframe and crank.
I am not suggesting that Sukhoi owners should switch to a 2 blade GT 250cm. Interesting that Jurgis Kairys apparently has suggested that a 270cm GT 2-blade prop will almost certainly have more static thrust than the MTV9. I do not have enough ground clearance to try that. My reason for testing on the SU26M : convenience. it is my aircraft and I know it well. My application is a very narrow niche indeed. Air shows are the only use for my SU26M. A Yak 52 enjoys much higher utility and would enjoy a prop that is a 'jack of all trades'.
And so would Yak 18's, CJ's, Murphies and a host of other general purpose M14P powered aircraft. The GT is a viable alternative to MT for an owner that already possesses a V530 hub or wishes to maintain a 2 blade vintage appearance. That is the point. Most Yak 52 owners do not do a dozen extreme gyroscopic maneuvers every day as I do in my Sukhoi, and will appreciate the larger aerobatic envelope of the GT 250 combined with less vibration, improved build quality, and repairability of the design. Pitts Model 12 owners that would aspire to fall into the Unlimited ranks would be better served with an MT.
Many pilots(myself included) have always felt that 2 blade props were inferior to 3 blade props for most applications. GT propellers changed this perception. Having borrowed V530 props on Sukhois in the past, this certainly was reinforced. After static balancing, they exhibited much higher vibration, lower climb rate, and lower static thrust than the 3 blade MT's. The planform of the GT blade is much different than the V530 blade. The character of the GT 250 blades is immediately different than the V530 blades. They have a lower, smoother sound. They have significantly less vibration. The static thrust is somewhere between the old MTV3 and new MTV9- much higher than the V530. I found the speed to be as high as any prop on my 360hp SU26M. I believe there is a valid niche for the GT prop in high utility applications. They now have a spinner that is the same general size as the large MTV9 spinner. It retrofits to V530 hubs. This alone may be an attractive and CHT reducing option for V530 hub owners.
Rick Volker
On Oct 26, 2009, at 10:58 PM, kevin kimball wrote:
[quote]Rick,
A follow up question or two.
Which prop do you chose to fly on your Sukhoi and why? What are the most important factors for you in prop selection for your M14P powered airplanes?
For us as used on the model 12, the key selection factors are:
Availability new, service, spinner choice, colors, appearance and most important, overall performance on our airplane.
Sincerely,
Kevin Kimball, Vice President
Jim Kimball Enterprises, Inc.
PO Box 849
5354 Cemetery Road
Zellwood, FL 32798-0849
407.889.3451 phone
407.889.7168 fax
www.pittsmodel12.com
www.jimkimballenterprises.com
Email: Kevin(at)jimkimballenterprises.com (Kevin(at)jimkimballenterprises.com)
On Oct 26, 2009, at 10:16 PM, Rick VOLKER wrote:
| Quote: | In reading my original prop comparison post, you will notice my "for more information, contact:". I chose not to display all information due to quantity, hoping any interested parties would contact me for the details. Let me fill you in:
On September 11,2009 at KIAG airport;
Flight one-1300 local time: MTV3. SU26M, full fuel. Density altitude 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight two-1430 local time: V530. SU26M, full fuel. Density altitude unchanged at 778'. Each test repeated three times during 25 minute flight with test average noted.
Flight three-1630 local time: GT 250 cm blades on V530 hub. SU26M, full fuel. Density altitude 774'. Each test repeated three times during 25 minute flight with test average noted.
On September 15,2009 at KIAG airport:
Flight one-1130 local time:MTV9. SU26M, full fuel. Density altitude 1037'. Altitude for tests changed to adjust for different density altitude. Each test repeated three times during 25 minute flight with test average noted.
Note;
-Aircraft weight was identical for each flight. Oil and fuel were exactly the same. The Profile for each flight was identical so that the weight of the aircraft would be identical for each part of the flight compared. Weather data can be confirmed via online sources.
-Static thrust was not directly measured, however stall speed tests under full power with this weight aircraft allowed gross comparisons of relative thrust at close to zero airspeed. Differences between aircraft were marked and statistically significant.
-The MTV9 was dynamic balanced on this aircraft before flight. Other props were not. I agree that dynamic balance performed on other aircraft are next to useless. Dynamic balance of V530 prop is more difficult on Yak 52 because of the proximity of blade to the ground allowing buffeting to limit ground run rpm and the lack of a spinner backplate for fine tuning.
The purpose of my post was to alert Yak 52 owners to a good alternative to MT if the original V530 blades must be replaced or if performance enhancements are desired. The price is not so expensive if you already have a good V530 hub. The MTV3 and MTV9-260-29 were owned by me and do not represent all of the choices in selecting a new MT prop.
My experience with MT has been mixed. A new MTV9-260-29 prop was so rough in flight that MT eventually sent me a new set of blades that corrected the problem, after 3 dynamic balance attempts with 2 complete tear-downs/inspections in between. But this all took one year. They do not yet know what was wrong with the original new blades. I had to find other props to get me through my air show season. MT did not have a loaner. I had a spare MTV3. GT Propellers also offered to loan me their blades for a spare V530 hub that I owned. A friend with a Yak 52 offered me a 20 hr TT V530. I compared them out of curiosity. It would have been much better to have an MTV9 of the proper length and type blade design with a Yak 52 to compare. The MTV3 has been around and many M14P pilots are familiar with them. The MTV9-260-29 is an airshow-only prop that is not suited for 90% of the types of flying done by Yak 52 pilots. I am satisfied with my MTV9-260-29 for my application. It allows me to do things that can not be done with any other prop. But you pay a price for this extreme. The high static thrust comes with a loss of max and cruise speeds. It also gives a crazy power off glide ratio that makes for some exciting air show antics. A well known MT dealer promised that his tests showed the MTV9-260-29 prop did everything well. Imagine that.
I was so impressed by the performance of the GT prop when compared with the original V530 blades, that I suggested to GT that I would sell them in the US. They have built a prop using the same construction techniques for a Spitfire Mk IX with 1700hp. The GT blades allow the Spitfire to remove manifold pressure limitations of all past designs and have been pull tested to prove their strength. This suggests that GT has the know how to build a prop that is strong enough for the M14P application. I hope that certification is achieved soon as scientifically done performance testing has been very convincing in GT's favor. I will look forward to seeing more testing done by others to compare the GT 250cm with the current MTV9 model offered for Yak52 V530 replacement.
Rick Volker
On Oct 26, 2009, at 2:03 PM, Richard Goode wrote:
| Quote: | I am disappointed by the lack of objectivity in Rick Volker's posting. Before anything else, and before I am accused of bias, could I make the following clear.
- I am a MT agent and sell a large number of MT propellers for a variety of applications.
- In Europe we have a significant problem of propellers, since MT, while excellent are expensive, and we can ONLY use certificated propellers. With ground strikes; old age etc we are running out of blades for our V-530s, and there simply are no other substitutes we can use.
- I have been a keen supporter of GT Propellers, and indeed am currently assisting them to get full European certification with EASA (our overall aviation controlling body)
- I have always been concerned about the safety of propellers. Some years ago I had a major failure on a propeller (not V-530/MT!) which was very nearly disastrous, and this is a fundamental reason why I am very careful about the propellers behind which I will fly, and which propellers I will recommend. There have been a number of high-profile propeller failures of non-certificated props, and, in my view, until a propeller has been properly tested AND certificated, I believe that any purchaser should tread very carefully.
To deal with the statistical evidence, I re-emphasise that I am very keen for the GT propellers to perform well against the more established props. Having said that I have been involved in extensive propeller trials, and I have concerns about the following issues:
- Ricks figures are a single figure for each propeller and each perameter. For properly objective tests you need to run each perameter at least three times.
- they are not mentioned so possibly he did them, but I doubt if there were proper corrections for temperature and pressure changes, which make a huge difference to these things. I am very aware of how long it takes to contact these tests, and things can change quite rapidly, particularly during the time that it takes to change from one propeller to another.
- Aircraft weights need to be exactly identical - it is all too easy to contact one test; fly again, without precisely filling fuel and oil to the same level.
- Rick refers to "more static thrust" - I do not see any figures, so wonder whether these were properly measured.
- Rick refers to "dynamically balanced", but clearly these props are being removed and put back on again, in which case the dynamic balance will certainly be lost. IF these propellers were not being immediately put on, then how long and over what period were the tests being conducted, and certainly if time has been taken to re-dynamically balance each propeller, then there must have been climatic changes.
- It is also slightly misleading to refer to the MTV3 propeller - this is an old design, long out of production, and only likely to be available second hand.
- For pricing, Rick is somewhat misleading to suggest that the GT propeller is half the price of MT. He gives a price of US $8,428, but this is only for two GT propeller blades. The current list price for a complete MTV-9-250 or 260 is US $15,600. This is of course for a factory new propeller, absolutely complete, whereas the GT price of US $8,428 is simply for two blades, so you then need to get a hub; overhaul it; install the blades; balance etc.
So to conclude, I am very much a supporter of GT propeller, and I am hoping that we are able to obtain full certification for their blades. BUT any performance / cost comparisons between propellers MUST be done scientifically and objectively!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340 120
Fax: +44 (0) 1544 340 129
www.russianaeros.com
p://www.matronics.com/Navigator?Yak-List
nics.com
w.matronics.com/contribution
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