Parkzone North American T-28 Trojan
06-02-2008, 07:54 AM
#1251
Senior Member
Join Date: May 2006
Location: Quincy, IL
Posts: 386
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
I have a stock trojan but replaced the receiver with a 6100 spectrum and have not had any problems. I have not noted any overheating issues. Regarding the batteries I fly both the 1800 and the 2200 lipos and to be honest I cannot tell any difference other than a slightly longer running time with the 2200. For the difference in price I would get the 2200 lipos. Here in the States the trojans went up $30.00 dollars in the last few days. I guess that they are a hot item. Good luck and enjoy your plane. I have not reinforced the wings but make sure that you tape down the stabilizer with the tape provided.
06-02-2008, 10:07 AM
#1252
Senior Member
Join Date: Jan 2007
Location: Hamilton,
NJ
Posts: 262
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
ORIGINAL: lou1947
Regarding the batteries I fly both the 1800 and the 2200 lipos and to be honest I cannot tell any difference other than a slightly longer running time with the 2200. For the difference in price I would get the 2200 lipos.
Regarding the batteries I fly both the 1800 and the 2200 lipos and to be honest I cannot tell any difference other than a slightly longer running time with the 2200. For the difference in price I would get the 2200 lipos.
The reason Lou1947 cannot tell any difference other than a slightly longer running time is because the MAH rating has very little to do with performance. Think of the MAH rating on Lipo's as the gas tank. The bigger the number the more "gallons" it holds therefore the longer you can go between fill ups (recharging). The performance numbers are the cell size (volts), usually expressed with an S hence 2s 3s 4s etc. and the C rating which determines amp output. For most park size planes a rating of from 15C 18C up to 20C is usually sufficient. I try to get all 20C batteries because they work best with all the planes I have. And yes each of these numbers has an effect on the price. More MAH = more $, more cells = more money, and larger C rating = more money. The least expensive increase is the C rating.
06-02-2008, 10:19 AM
#1253
Junior Member
My Feedback: (4)
Join Date: Jul 2003
Location: Franklin, KY,
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
Well, I crashed my T-28 this weekend and completely destroyed my cowl and motor mount. I can find the motor mounts online but everywhere I check the cowls are on backorder. Does anyone here know where I could find the cowl in stock?
06-02-2008, 02:11 PM
#1254
Senior Member
Join Date: Jun 2006
Location: cleveland ,
OH
Posts: 390
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
ORIGINAL: guapoman2000
35 MPH??????
Lets see Propeller Pitch speed is pretty straightforward
Pitch x rpm
Therefore, propeller RPMs = Top Speed MPH / Pitch
In your post, you said that your T-28 top speed is 35 MPH so,
Propeller RPMs = 35 MPH / 7.5
Since the Pitch Speed is in units of Inches per Minute we have to convert to Miles Per Hour therefore,
(7.5 inches/minute)*(60 minutes/ 1 hour)*(1 foot/12 inches)*(1 Mile/5280 Feet) = .0071023 Miles per Hour
Okay,
Propeller RPMs = 35 MPH / .0071023 = 4,927 RPMs at the propeller [:@] <-That is pretty slow!!!!!![X(]
Have you measured your Propeller RPMs? The reason I ask is because the STOCK ParkZone T-28 motor is the 480 Outrunner that delivers 960 Kv ( 960 RPMs / Volt)!!!
http://www.redrockethobbies.com/Park..._p/pkz4416.htm
Without considering motor, ESC, mechanical losses, your typical Off-The-Charger Voltage for a typical 3-Cell, Li-POLY is 12.4 Volts and under Wide open Throttle lets say the Battery's Under Load Voltage dips down to 11.4 Volts so, therefore,
(960 RPMs / Volt) X (11.4 Volts) = 10,944 RPMs @ Propeller
Pitch speed = 10,944 RPMs * (.0071023 Mile/Hour) = 77 MPH[:@]
There might be a possibility that my Batteries are dropping too much ( voltage under load) and it is going 60.9 MPH due to that FAT FUSE Drag!!!
35 MPH??????
Lets see Propeller Pitch speed is pretty straightforward
Pitch x rpm
Therefore, propeller RPMs = Top Speed MPH / Pitch
In your post, you said that your T-28 top speed is 35 MPH so,
Propeller RPMs = 35 MPH / 7.5
Since the Pitch Speed is in units of Inches per Minute we have to convert to Miles Per Hour therefore,
(7.5 inches/minute)*(60 minutes/ 1 hour)*(1 foot/12 inches)*(1 Mile/5280 Feet) = .0071023 Miles per Hour
Okay,
Propeller RPMs = 35 MPH / .0071023 = 4,927 RPMs at the propeller [:@] <-That is pretty slow!!!!!![X(]
Have you measured your Propeller RPMs? The reason I ask is because the STOCK ParkZone T-28 motor is the 480 Outrunner that delivers 960 Kv ( 960 RPMs / Volt)!!!
http://www.redrockethobbies.com/Park..._p/pkz4416.htm
Without considering motor, ESC, mechanical losses, your typical Off-The-Charger Voltage for a typical 3-Cell, Li-POLY is 12.4 Volts and under Wide open Throttle lets say the Battery's Under Load Voltage dips down to 11.4 Volts so, therefore,
(960 RPMs / Volt) X (11.4 Volts) = 10,944 RPMs @ Propeller
Pitch speed = 10,944 RPMs * (.0071023 Mile/Hour) = 77 MPH[:@]
There might be a possibility that my Batteries are dropping too much ( voltage under load) and it is going 60.9 MPH due to that FAT FUSE Drag!!!
06-02-2008, 06:21 PM
#1255
RE: Parkzone North American T-28 Trojan
ORIGINAL: GaGeeBees
Okay, if you say so. I can tell you with absolute certainty that neither of my two stock Trojans fly anywhere near 60 mph. They might do 30 - 35 and possibly a bit more than that in a dive but not even close to 60.
ORIGINAL: guapoman2000
As long as the "GPS" receiver is not under a roof structure like inside a building, it is no different than, having a GPS navigator device like in a car such as:
http://reviews.cnet.com/gps-kits/pal...-32382724.html
ORIGINAL: GaGeeBees
How does the GPS "see" the satellites when the hatch is in place? I wouldn't think it would work but I could be wrong.
How does the GPS "see" the satellites when the hatch is in place? I wouldn't think it would work but I could be wrong.
http://reviews.cnet.com/gps-kits/pal...-32382724.html
GaGeeBees,
I realize that GPS receivers are used in various other hobbies but, I have been using my Garmin geko 201 very successfully within various models and the Desk Work and other devices such as the use of Timing clock on the ground reference have verified the accuracy of my Garmin "GPS" receiver and I will stand by it.
Not to prove anything here just to provide you additional data, I took out my Propeller Tech meter specially built for our hobby as it measures 2-Blade, 3-Blade and even 4-Bladed propellers plus I hooked up my Astro Flight WATT meter and here's the data plus Pictures of the actual testing when I got home from work and saw your above post with your data.
1/2 Thottle Prop. RPMs measurement: 6,710 RPMs Static
1/2 Throttle AMP/WATT meas.: Picture image did not come out
Wide Open Throttle Prop RPMs Meas.: 7,920 RPM Static
Wide Open Throttle AMP/WATT Meas.: 18.5 AMPs / 208 Watts / 11.35 Volts
Therefore, at Wide Open almost 8,000 RPMs at the propeller can be calculated and RECALL THIS IS STATIC,
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
Pitch Speed (Static) = .0071023 X 8,000 = 57 MPH (Static)
Actual Ground speed measurement from my Garmin geko 201 was: 60.9 MPH
I think that I will continue to use my Garmin "GPS" receiver on all my models.
06-02-2008, 06:41 PM
#1256
RE: Parkzone North American T-28 Trojan
Just to be perfectly CLEAR and HONEST!!!
That morning, I flew my T-28 up and down the field and the wind was perhaps 4 - 5 MPH coming from the South-South East. The model was flying directly into the wind and I turned her with the wind. Recall that I did not Thottle BACK
Therefore, the Garmin "GPS" Receiver will record the highest ground speed and hence the tail "wind" assist when I turned her with the wind [:@]
That morning, I flew my T-28 up and down the field and the wind was perhaps 4 - 5 MPH coming from the South-South East. The model was flying directly into the wind and I turned her with the wind. Recall that I did not Thottle BACK
Therefore, the Garmin "GPS" Receiver will record the highest ground speed and hence the tail "wind" assist when I turned her with the wind [:@]
06-02-2008, 06:52 PM
#1257
My Feedback: (23)
Join Date: Sep 2004
Location: Fayetteville,
GA
Posts: 1,413
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
ORIGINAL: wedgewing
Interesting thread on the top speed of a GPS laiden Trojan. In a funny way it reminds me of the Monty Python 'A swallow carrying a coconut?' scene
Interesting thread on the top speed of a GPS laiden Trojan. In a funny way it reminds me of the Monty Python 'A swallow carrying a coconut?' scene
06-02-2008, 07:01 PM
#1258
RE: Parkzone North American T-28 Trojan
ORIGINAL: GaGeeBees
LOL African or European?? I was reminded of the same thing.
ORIGINAL: wedgewing
Interesting thread on the top speed of a GPS laiden Trojan. In a funny way it reminds me of the Monty Python 'A swallow carrying a coconut?' scene
Interesting thread on the top speed of a GPS laiden Trojan. In a funny way it reminds me of the Monty Python 'A swallow carrying a coconut?' scene
06-02-2008, 07:11 PM
#1260
RE: Parkzone North American T-28 Trojan
ORIGINAL: casey_lamm
whats are we trying to do, record the top speed of the t-28?
whats are we trying to do, record the top speed of the t-28?
No, you can discuss anything your heart contents such as it is about T-28 Trojan by ParkZone!!![:@]
06-02-2008, 07:11 PM
#1261
Senior Member
Join Date: Jan 2008
Location: Valencia,
CA
Posts: 149
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
ORIGINAL: GaGeeBees
LOL African or European?? I was reminded of the same thing.
ORIGINAL: wedgewing
Interesting thread on the top speed of a GPS laiden Trojan. In a funny way it reminds me of the Monty Python 'A swallow carrying a coconut?' scene
Interesting thread on the top speed of a GPS laiden Trojan. In a funny way it reminds me of the Monty Python 'A swallow carrying a coconut?' scene
LOLOLOLOLO..it reminds me of one of Ron White's HBO special I watched called..."You can't fix stupid!'
06-02-2008, 07:15 PM
#1262
RE: Parkzone North American T-28 Trojan
ORIGINAL: adamic39
Does anyone know if either the fw190 or p51 cowl fit the t28? Maybe with a little bit of modification?
Does anyone know if either the fw190 or p51 cowl fit the t28? Maybe with a little bit of modification?
06-02-2008, 07:21 PM
#1263
RE: Parkzone North American T-28 Trojan
ORIGINAL: 11Hotel
Ha! No, I learned a long time ago that banana's and planes don't mix!
Next contestant?
Ha! No, I learned a long time ago that banana's and planes don't mix!
Next contestant?
To some creatures, all they can think about and eat is a Banana!!!!
06-02-2008, 07:36 PM
#1264
My Feedback: (23)
Join Date: Sep 2004
Location: Fayetteville,
GA
Posts: 1,413
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
ORIGINAL: guapoman2000
35 MPH??????
Lets see Propeller Pitch speed is pretty straightforward
Pitch x rpm
Therefore, propeller RPMs = Top Speed MPH / Pitch
In your post, you said that your T-28 top speed is 35 MPH so,
Propeller RPMs = 35 MPH / 7.5
Since the Pitch Speed is in units of Inches per Minute we have to convert to Miles Per Hour therefore,
(7.5 inches/minute)*(60 minutes/ 1 hour)*(1 foot/12 inches)*(1 Mile/5280 Feet) = .0071023 Miles per Hour
Okay,
Propeller RPMs = 35 MPH / .0071023 = 4,927 RPMs at the propeller [:@] <-That is pretty slow!!!!!![X(]
Have you measured your Propeller RPMs? The reason I ask is because the STOCK ParkZone T-28 motor is the 480 Outrunner that delivers 960 Kv ( 960 RPMs / Volt)!!!
http://www.redrockethobbies.com/Park..._p/pkz4416.htm
Without considering motor, ESC, mechanical losses, your typical Off-The-Charger Voltage for a typical 3-Cell, Li-POLY is 12.4 Volts and under Wide open Throttle lets say the Battery's Under Load Voltage dips down to 11.4 Volts so, therefore,
(960 RPMs / Volt) X (11.4 Volts) = 10,944 RPMs @ Propeller
Pitch speed = 10,944 RPMs * (.0071023 Mile/Hour) = 77 MPH[:@]
There might be a possibility that my Batteries are dropping too much ( voltage under load) and it is going 60.9 MPH due to that FAT FUSE Drag!!!
GaGeeBees,
I realize that GPS receivers are used in various other hobbies but, I have been using my Garmin geko 201 very successfully within various models and the Desk Work and other devices such as the use of Timing clock on the ground reference have verified the accuracy of my Garmin "GPS" receiver and I will stand by it.
Not to prove anything here just to provide you additional data, I took out my Propeller Tech meter specially built for our hobby as it measures 2-Blade, 3-Blade and even 4-Bladed propellers plus I hooked up my Astro Flight WATT meter and here's the data plus Pictures of the actual testing when I got home from work and saw your above post with your data.
1/2 Thottle Prop. RPMs measurement: 6,710 RPMs Static
1/2 Throttle AMP/WATT meas.: Picture image did not come out
Wide Open Throttle Prop RPMs Meas.: 7,920 RPM Static
Wide Open Throttle AMP/WATT Meas.: 18.5 AMPs / 208 Watts / 11.35 Volts
Therefore, at Wide Open almost 8,000 RPMs at the propeller can be calculated and RECALL THIS IS STATIC,
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
Pitch Speed (Static) = .0071023 X 8,000 = 57 MPH (Static)
Actual Ground speed measurement from my Garmin geko 201 was: 60.9 MPH
I think that I will continue to use my Garmin "GPS" receiver on all my models.
35 MPH??????
Lets see Propeller Pitch speed is pretty straightforward
Pitch x rpm
Therefore, propeller RPMs = Top Speed MPH / Pitch
In your post, you said that your T-28 top speed is 35 MPH so,
Propeller RPMs = 35 MPH / 7.5
Since the Pitch Speed is in units of Inches per Minute we have to convert to Miles Per Hour therefore,
(7.5 inches/minute)*(60 minutes/ 1 hour)*(1 foot/12 inches)*(1 Mile/5280 Feet) = .0071023 Miles per Hour
Okay,
Propeller RPMs = 35 MPH / .0071023 = 4,927 RPMs at the propeller [:@] <-That is pretty slow!!!!!![X(]
Have you measured your Propeller RPMs? The reason I ask is because the STOCK ParkZone T-28 motor is the 480 Outrunner that delivers 960 Kv ( 960 RPMs / Volt)!!!
http://www.redrockethobbies.com/Park..._p/pkz4416.htm
Without considering motor, ESC, mechanical losses, your typical Off-The-Charger Voltage for a typical 3-Cell, Li-POLY is 12.4 Volts and under Wide open Throttle lets say the Battery's Under Load Voltage dips down to 11.4 Volts so, therefore,
(960 RPMs / Volt) X (11.4 Volts) = 10,944 RPMs @ Propeller
Pitch speed = 10,944 RPMs * (.0071023 Mile/Hour) = 77 MPH[:@]
There might be a possibility that my Batteries are dropping too much ( voltage under load) and it is going 60.9 MPH due to that FAT FUSE Drag!!!
GaGeeBees,
I realize that GPS receivers are used in various other hobbies but, I have been using my Garmin geko 201 very successfully within various models and the Desk Work and other devices such as the use of Timing clock on the ground reference have verified the accuracy of my Garmin "GPS" receiver and I will stand by it.
Not to prove anything here just to provide you additional data, I took out my Propeller Tech meter specially built for our hobby as it measures 2-Blade, 3-Blade and even 4-Bladed propellers plus I hooked up my Astro Flight WATT meter and here's the data plus Pictures of the actual testing when I got home from work and saw your above post with your data.
1/2 Thottle Prop. RPMs measurement: 6,710 RPMs Static
1/2 Throttle AMP/WATT meas.: Picture image did not come out
Wide Open Throttle Prop RPMs Meas.: 7,920 RPM Static
Wide Open Throttle AMP/WATT Meas.: 18.5 AMPs / 208 Watts / 11.35 Volts
Therefore, at Wide Open almost 8,000 RPMs at the propeller can be calculated and RECALL THIS IS STATIC,
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
Pitch Speed (Static) = .0071023 X 8,000 = 57 MPH (Static)
Actual Ground speed measurement from my Garmin geko 201 was: 60.9 MPH
I think that I will continue to use my Garmin "GPS" receiver on all my models.
Thanks for all the unsolicited "data" and the very interesting example of your mathematical approach to determining speed based on prop pitch & rpm. As fascinating as your information may be, my results don't match. I was able to do some additional flights on both of my Trojans today. I used my radar gun and a second, newer gun to verify the results. I used five different batteries, all 11.1 volt LiPo. Averaging all readings from both guns for all flights yielded an average speed for a straight and level pass of 38.7 mph. The highest speed attained on any pass was 48 mph. I also had one pass each at 46, 45 and 43 mph. The rest of the passes were slower. I limited flight times for each battery to not more than six minutes in order to not skew the averages downward by flying passes with near-discharged batteries. The two radar guns agreed over 95% of the time and the largest difference in readings between the two was 2 mph. Wind speed for this test varied from none to a very slight breeze. Of course these are my results only and may or may not be representative of the typical or average plane. As the auto companies like to say: YMMV (your mileage may vary).
06-02-2008, 07:40 PM
#1265
RE: Parkzone North American T-28 Trojan
ORIGINAL: GaGeeBees
Gua-man,
Thanks for all the unsolicited "data" and the very interesting example of your mathematical approach to determining speed based on prop pitch & rpm. As fascinating as your information may be, my results don't match. I was able to do some additional flights on both of my Trojans today. I used my radar gun and a second, newer gun to verify the results. I used five different batteries, all 11.1 volt LiPo. Averaging all readings from both guns for all flights yielded an average speed for a straight and level pass of 38.7 mph. The highest speed attained on any pass was 48 mph. I also had one pass each at 46, 45 and 43 mph. The rest of the passes were slower. I limited flight times for each battery to not more than six minutes in order to not skew the averages downward by flying passes with near-discharged batteries. The two radar guns agreed over 95% of the time and the largest difference in readings between the two was 2 mph. Wind speed for this test varied from none to a very slight breeze. Of course these are my results only and may or may not be representative of the typical or average plane. As the auto companies like to say: YMMV (your mileage may vary).
ORIGINAL: guapoman2000
35 MPH??????
Lets see Propeller Pitch speed is pretty straightforward
Pitch x rpm
Therefore, propeller RPMs = Top Speed MPH / Pitch
In your post, you said that your T-28 top speed is 35 MPH so,
Propeller RPMs = 35 MPH / 7.5
Since the Pitch Speed is in units of Inches per Minute we have to convert to Miles Per Hour therefore,
(7.5 inches/minute)*(60 minutes/ 1 hour)*(1 foot/12 inches)*(1 Mile/5280 Feet) = .0071023 Miles per Hour
Okay,
Propeller RPMs = 35 MPH / .0071023 = 4,927 RPMs at the propeller [:@] <-That is pretty slow!!!!!![X(]
Have you measured your Propeller RPMs? The reason I ask is because the STOCK ParkZone T-28 motor is the 480 Outrunner that delivers 960 Kv ( 960 RPMs / Volt)!!!
http://www.redrockethobbies.com/Park..._p/pkz4416.htm
Without considering motor, ESC, mechanical losses, your typical Off-The-Charger Voltage for a typical 3-Cell, Li-POLY is 12.4 Volts and under Wide open Throttle lets say the Battery's Under Load Voltage dips down to 11.4 Volts so, therefore,
(960 RPMs / Volt) X (11.4 Volts) = 10,944 RPMs @ Propeller
Pitch speed = 10,944 RPMs * (.0071023 Mile/Hour) = 77 MPH[:@]
There might be a possibility that my Batteries are dropping too much ( voltage under load) and it is going 60.9 MPH due to that FAT FUSE Drag!!!
GaGeeBees,
I realize that GPS receivers are used in various other hobbies but, I have been using my Garmin geko 201 very successfully within various models and the Desk Work and other devices such as the use of Timing clock on the ground reference have verified the accuracy of my Garmin "GPS" receiver and I will stand by it.
Not to prove anything here just to provide you additional data, I took out my Propeller Tech meter specially built for our hobby as it measures 2-Blade, 3-Blade and even 4-Bladed propellers plus I hooked up my Astro Flight WATT meter and here's the data plus Pictures of the actual testing when I got home from work and saw your above post with your data.
1/2 Thottle Prop. RPMs measurement: 6,710 RPMs Static
1/2 Throttle AMP/WATT meas.: Picture image did not come out
Wide Open Throttle Prop RPMs Meas.: 7,920 RPM Static
Wide Open Throttle AMP/WATT Meas.: 18.5 AMPs / 208 Watts / 11.35 Volts
Therefore, at Wide Open almost 8,000 RPMs at the propeller can be calculated and RECALL THIS IS STATIC,
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
Pitch Speed (Static) = .0071023 X 8,000 = 57 MPH (Static)
Actual Ground speed measurement from my Garmin geko 201 was: 60.9 MPH
I think that I will continue to use my Garmin "GPS" receiver on all my models.
35 MPH??????
Lets see Propeller Pitch speed is pretty straightforward
Pitch x rpm
Therefore, propeller RPMs = Top Speed MPH / Pitch
In your post, you said that your T-28 top speed is 35 MPH so,
Propeller RPMs = 35 MPH / 7.5
Since the Pitch Speed is in units of Inches per Minute we have to convert to Miles Per Hour therefore,
(7.5 inches/minute)*(60 minutes/ 1 hour)*(1 foot/12 inches)*(1 Mile/5280 Feet) = .0071023 Miles per Hour
Okay,
Propeller RPMs = 35 MPH / .0071023 = 4,927 RPMs at the propeller [:@] <-That is pretty slow!!!!!![X(]
Have you measured your Propeller RPMs? The reason I ask is because the STOCK ParkZone T-28 motor is the 480 Outrunner that delivers 960 Kv ( 960 RPMs / Volt)!!!
http://www.redrockethobbies.com/Park..._p/pkz4416.htm
Without considering motor, ESC, mechanical losses, your typical Off-The-Charger Voltage for a typical 3-Cell, Li-POLY is 12.4 Volts and under Wide open Throttle lets say the Battery's Under Load Voltage dips down to 11.4 Volts so, therefore,
(960 RPMs / Volt) X (11.4 Volts) = 10,944 RPMs @ Propeller
Pitch speed = 10,944 RPMs * (.0071023 Mile/Hour) = 77 MPH[:@]
There might be a possibility that my Batteries are dropping too much ( voltage under load) and it is going 60.9 MPH due to that FAT FUSE Drag!!!
GaGeeBees,
I realize that GPS receivers are used in various other hobbies but, I have been using my Garmin geko 201 very successfully within various models and the Desk Work and other devices such as the use of Timing clock on the ground reference have verified the accuracy of my Garmin "GPS" receiver and I will stand by it.
Not to prove anything here just to provide you additional data, I took out my Propeller Tech meter specially built for our hobby as it measures 2-Blade, 3-Blade and even 4-Bladed propellers plus I hooked up my Astro Flight WATT meter and here's the data plus Pictures of the actual testing when I got home from work and saw your above post with your data.
1/2 Thottle Prop. RPMs measurement: 6,710 RPMs Static
1/2 Throttle AMP/WATT meas.: Picture image did not come out
Wide Open Throttle Prop RPMs Meas.: 7,920 RPM Static
Wide Open Throttle AMP/WATT Meas.: 18.5 AMPs / 208 Watts / 11.35 Volts
Therefore, at Wide Open almost 8,000 RPMs at the propeller can be calculated and RECALL THIS IS STATIC,
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
Pitch Speed (Static) = .0071023 X 8,000 = 57 MPH (Static)
Actual Ground speed measurement from my Garmin geko 201 was: 60.9 MPH
I think that I will continue to use my Garmin "GPS" receiver on all my models.
Thanks for all the unsolicited "data" and the very interesting example of your mathematical approach to determining speed based on prop pitch & rpm. As fascinating as your information may be, my results don't match. I was able to do some additional flights on both of my Trojans today. I used my radar gun and a second, newer gun to verify the results. I used five different batteries, all 11.1 volt LiPo. Averaging all readings from both guns for all flights yielded an average speed for a straight and level pass of 38.7 mph. The highest speed attained on any pass was 48 mph. I also had one pass each at 46, 45 and 43 mph. The rest of the passes were slower. I limited flight times for each battery to not more than six minutes in order to not skew the averages downward by flying passes with near-discharged batteries. The two radar guns agreed over 95% of the time and the largest difference in readings between the two was 2 mph. Wind speed for this test varied from none to a very slight breeze. Of course these are my results only and may or may not be representative of the typical or average plane. As the auto companies like to say: YMMV (your mileage may vary).
Where can I get a cheap but, reliable RADAR gun????
Would certainly be interesting comparision.
I like the 48 MPH!!!!
Appreciate you providing that updated data......SEE I MADE YOU FLY AGAIN!!!!!
Thanks!!!
Carlos
06-02-2008, 07:43 PM
#1266
RE: Parkzone North American T-28 Trojan
I am sure the RADAR Gun must be "more" accurate than the GPS Receiver as someone at RCGroups has informed me the possibility of Errors from trangulation techniques used in the "GPS" Software.
Radar Gun transmitts a wave at certain frequency and receives a reflection based on a stationary reference, correct?
Man I thought that 60 MPH was just too good.
Thanks!!!
Carlos
Radar Gun transmitts a wave at certain frequency and receives a reflection based on a stationary reference, correct?
Man I thought that 60 MPH was just too good.
Thanks!!!
Carlos
06-02-2008, 07:48 PM
#1267
My Feedback: (23)
Join Date: Sep 2004
Location: Fayetteville,
GA
Posts: 1,413
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
Hey!!!!!
Where can I get a cheap but, reliable RADAR gun????
Would certainly be interesting comparision.
I like the 48 MPH!!!!
Appreciate you providing that updated data......SEE I MADE YOU FLY AGAIN!!!!!
Thanks!!!
Carlos
I bought mine at www.mcmaster.com it's a Bushnell and cost around $120 if I remember correctly.
I agree with you, 48 mph isn't bad for a foamie!
Thanks,
Paul
06-02-2008, 08:05 PM
#1268
RE: Parkzone North American T-28 Trojan
Paul,
Sweat!!!! Wow, nice features, I like the Point and Shoot!!!!
Someone in the "Other" T-28 Trojan Thread suggested a $30 radar Gun from Wal-Mart, hum......
I will pay a little bit more and get a pro Radar Gun!
Thanks again!!
Carlos
Sweat!!!! Wow, nice features, I like the Point and Shoot!!!!
Someone in the "Other" T-28 Trojan Thread suggested a $30 radar Gun from Wal-Mart, hum......
I will pay a little bit more and get a pro Radar Gun!
Thanks again!!
Carlos
06-02-2008, 08:25 PM
#1270
RE: Parkzone North American T-28 Trojan
Okay, sorry for the tangent discussion about Max Speed and Radar Guns!!
Everyone can go back to the rather dull discussions of Receiver Glitches!!!!
Everyone can go back to the rather dull discussions of Receiver Glitches!!!!
06-02-2008, 09:52 PM
#1271
Junior Member
Join Date: Jul 2005
Location: Surrey,
BC, CANADA
Posts: 19
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
I have built a site to keep all of my rc videos There are some great Trojan videos. Have a look http://rcsuperstore.ning.com and let me know what you think.
06-02-2008, 10:01 PM
#1272
Junior Member
Join Date: Sep 2007
Location: Oro Valley, AZ
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
ORIGINAL: guapoman2000
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
7.5 Pitch is in Inches per Minute thereby equates to .0071023 Miles per Hours
So,
Pitch Speed = Propeller Pitch X Prop RPMs
06-03-2008, 06:53 AM
#1273
Senior Member
Join Date: Jul 2007
Location: Sydney, AUSTRALIA
Posts: 542
Likes: 0
Received 0 Likes
on
0 Posts
RE: Parkzone North American T-28 Trojan
...someone at RCGroups has informed me the possibility of Errors from trangulation techniques used in the "GPS" Software.
I think that triangulation error would be more of a factor with the radar gun. If the plane is flying straight and level at 30 feet off of the ground and coming towards you from 40 feet away, the radar gun measures the change in length of the hypotenuse of the right triangle. So say it was measuring in feet per second and something was traveling at 10 fps (60 miles/hr * 5280 feet/mile * (1 hr/60 min) * (1 min/60 sec) = 88 fps, but using 10 fps makes the example more clear) . In one second, the straight line distance traveled by the airplane is 10 feet. Prior to the second, the airplane was 50 feet, straight line, away from the radar gun (30^2 + 40^2 = 50^2). After the second in which the airplane traveled 10 feet, the airplane was 42.4 feet away from the radar gun (30^2 + 30^2 = 42.43^2), so the radar gun only "sees" a speed of 50-42.4 or roughly 7.6 feet per second, an error of over 20 percent. The error is less if the plane is lower or further away (less of a vertical leg on the right triangle, so the 30^2 becomes small compared to the distance in the direction traveled), but measuring with the radar gun does introduce errors if the plane isn't headed straight at the gun.
A more accurate way to measure the speed would be to fly it straight along a football field and have someone stand on one goal line and wave a flag when it passes, and have someone else standing on the other goal line start a stopwatch when the flag waves and stop it when it passes his goal line. As the field is 300 feet, the speed/time relationship looks like (assuming the effect of the finite speed of light is negligible, which it is at these speeds):
3 seconds = 100 feet/sec = 68.2 MPH
3.2 seconds = 93.75 ft/sec = 63.9 MPH
3.4 seconds = 88.2 ft/sec = 60.2 MPH
3.6 seconds = 83.3 ft/sec = 56.8 MPH
3.8 seconds = 78.9 ft/sec = 53.8 MPH
4 seconds = 75 ft/sec = 51.1 MPH
4.2 seconds = 71.4 ft/sec = 47.7 MPH
4.4 seconds = 68.2 ft/sec = 46.5 MPH
4.6 seconds = 65.2 ft/sec = 44.5 MPH
4.8 seconds = 62.5 ft/sec = 42.6 MPH
5 seconds = 60 ft/sec = 40.9 MPH
So instead of a $120 radar gun, you just need 2 people, a football field, and a stopwatch.
