What is the airspeed of F3a models??
10-12-2014, 07:30 AM
#1
Thread Starter
What is the airspeed of F3a models??
Hi,
Has any done a lazergun measurement of a horizontal pass of a F3a model?
Iam very interested to hear about this.
Thank you
Has any done a lazergun measurement of a horizontal pass of a F3a model?
Iam very interested to hear about this.
Thank you
10-12-2014, 01:19 PM
#4
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But the question hasn't been answered. I'm curious too and wonder if anyone has ever actually checked with a radar gun. I suspect in excess of 100 mph.
I remember years ago when I participated in one of the cross country deals Bob Rich organized we flew a Senior Falcon at just above idle to not outrun our truck going 55 mph on the Interstate roads.
Dave
I remember years ago when I participated in one of the cross country deals Bob Rich organized we flew a Senior Falcon at just above idle to not outrun our truck going 55 mph on the Interstate roads.
Dave
Last edited by burtona; 10-12-2014 at 01:22 PM.
10-12-2014, 04:27 PM
#6
I last checked a couple years ago when doing some testing of single prop electric vs contra. Straight and level full throttle is typically 105 mph +/-. Horizontal "cruise" speed in the sequence is typically 75 mph +/-. To a well trained eye, 5 mph is a pretty big difference in speed.
10-12-2014, 11:42 PM
#7
Thread Starter
To all contributors
Thank you
Testing 75-80mi airspeed. This is approx 120 km/h= 33.33m/s = 110ft/sec
Say distance within sectors are about 500-600m it will take about 16sec to fly the distance, that seems to be a little slow??????????
I know that some European like to fly very slow, but I am after the average speed that is a normal speed.
I still like to hear about your experience re horizontal airspeed.
Regards
Thank you
Testing 75-80mi airspeed. This is approx 120 km/h= 33.33m/s = 110ft/sec
Say distance within sectors are about 500-600m it will take about 16sec to fly the distance, that seems to be a little slow??????????
I know that some European like to fly very slow, but I am after the average speed that is a normal speed.
I still like to hear about your experience re horizontal airspeed.
Regards
10-13-2014, 02:45 AM
#8
Top speed in level flight would depend on top RPM and pitch. I would say the speeds you are saying are too high.
In level flight through the pattern, I am at around 5/8 ths throttle which is about 4500 rpm. The pitch is 10", so doing the calculations speed is around 70 kmh.
Doing the calculations using my set up, ie. 7200 rpm, 10" pitch, top speed would be 110 kmh.
In level flight through the pattern, I am at around 5/8 ths throttle which is about 4500 rpm. The pitch is 10", so doing the calculations speed is around 70 kmh.
Doing the calculations using my set up, ie. 7200 rpm, 10" pitch, top speed would be 110 kmh.
Last edited by drac1; 10-13-2014 at 02:51 AM.
10-13-2014, 04:34 AM
#9
Thread Starter
Top speed in level flight would depend on top RPM and pitch. I would say the speeds you are saying are too high.
In level flight through the pattern, I am at around 5/8 ths throttle which is about 4500 rpm. The pitch is 10", so doing the calculations speed is around 70 kmh.
Doing the calculations using my set up, ie. 7200 rpm, 10" pitch, top speed would be 110 kmh.
In level flight through the pattern, I am at around 5/8 ths throttle which is about 4500 rpm. The pitch is 10", so doing the calculations speed is around 70 kmh.
Doing the calculations using my set up, ie. 7200 rpm, 10" pitch, top speed would be 110 kmh.
70km/h =70000/3600=19.44m/sec = 500/19,44= 26 sec to fly 500-600 meters. Dont you think that is a bit slow????
The top speed at 110km/h=110000/3600=30,55m/s= 500/30,55=16,4 sec to fly 500-600m
Maybe that 110-120 km/h is a good average??????
Still loking for answers.
Regards
10-13-2014, 04:56 AM
#10
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Dag,
Observation from a fan who watches a bit of F3a.. As you know, the box is 60 degrees either side of centerline with the airplane 150m out. I have timed a couple of top pilots flying this line and it is an 8 count. In the vertical they do a four count. one one thousand... two one thousand..... ... ...
So with a length of the box at 519m that would be 64m/s or 143 mph. of course if that was a 9 count = 57 m/s or 127 mph or if it was a 10 count = 51 m/s or 114 mph
Ken
PS: tae the math for what it's worth.. based on observations,, not radar..
Observation from a fan who watches a bit of F3a.. As you know, the box is 60 degrees either side of centerline with the airplane 150m out. I have timed a couple of top pilots flying this line and it is an 8 count. In the vertical they do a four count. one one thousand... two one thousand..... ... ...
So with a length of the box at 519m that would be 64m/s or 143 mph. of course if that was a 9 count = 57 m/s or 127 mph or if it was a 10 count = 51 m/s or 114 mphKen
PS: tae the math for what it's worth.. based on observations,, not radar..
10-13-2014, 05:07 AM
#11
Thread Starter
Dag,
Observation from a fan who watches a bit of F3a.. As you know, the box is 60 degrees either side of centerline with the airplane 150m out. I have timed a couple of top pilots flying this line and it is an 8 count. In the vertical they do a four count. one one thousand... two one thousand..... ... ... So with a length of the box at 519m that would be 64m/s or 143 mph. of course if that was a 9 count = 57 m/s or 127 mph or if it was a 10 count = 51 m/s or 114 mph
Ken
PS: tae the math for what it's worth.. based on observations,, not radar..
Observation from a fan who watches a bit of F3a.. As you know, the box is 60 degrees either side of centerline with the airplane 150m out. I have timed a couple of top pilots flying this line and it is an 8 count. In the vertical they do a four count. one one thousand... two one thousand..... ... ...
So with a length of the box at 519m that would be 64m/s or 143 mph. of course if that was a 9 count = 57 m/s or 127 mph or if it was a 10 count = 51 m/s or 114 mphKen
PS: tae the math for what it's worth.. based on observations,, not radar..
This is very interesting. Your 8count, can that be translated to something like 8-10 sec???????
Still loking for more input, thanks!
Regards
10-13-2014, 12:05 PM
#12
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A couple of years ago I did a 4000 word investigation on the polar curve and glide curve of my F3A biplane. This required true airspeed measurements and change in altitude measurements, for which I used Spektrum telemetry to get my data (before it was easy to get that data lol). I'll upload my results once I get back from school today.
10-13-2014, 12:42 PM
#13
On mine, 220kv motor and an 11 inch pitch prop yields a theoretical top speed of 84.79 mph. I know it's much less...I've had other similar planes radar checked that were around 60 - 70 mph..
10-13-2014, 01:10 PM
#14
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A few weeks ago, out of curiosity I made a few flights (P15&F15) with my Arixtra+, carrying a Graupner GPS/variometer telemetry module. I'm not so sure of the accuracy of the logged airspeed, especially when climbing and descending (not sure how 'clever' calculations beeing done). Anyhow, here is a plot from one of the flights (seems to be F15) showing the altitude [m] (green) and speed [km/h] (blue) :
Last edited by ofremmi; 10-13-2014 at 01:13 PM.
10-13-2014, 01:36 PM
#15
Hi and Thanks for answer,
70km/h =70000/3600=19.44m/sec = 500/19,44= 26 sec to fly 500-600 meters. Dont you think that is a bit slow????
The top speed at 110km/h=110000/3600=30,55m/s= 500/30,55=16,4 sec to fly 500-600m
Maybe that 110-120 km/h is a good average??????
Still loking for answers.
Regards
70km/h =70000/3600=19.44m/sec = 500/19,44= 26 sec to fly 500-600 meters. Dont you think that is a bit slow????
The top speed at 110km/h=110000/3600=30,55m/s= 500/30,55=16,4 sec to fly 500-600m
Maybe that 110-120 km/h is a good average??????
Still loking for answers.
Regards
We never fly level flight for the complete length of the box, so how long it would take doesn't really mean anything. With the schedules and planes today, we are flying slower. Top speed is irrelevant as we never do it.
There was cop with a radar gun at our field last Saturday. I didn't radar my pattern model, but my sport models top speed was within 10 kmh of the speed I calculated it would reach. So I am confident the speeds I have listed above are pretty accurate.
10-13-2014, 04:44 PM
#16
A few years ago, I remember reading an article by Dean Pappas in FM where he stated that he liked his models to be able to reach about 85 mph going full bore. I believe the reason he gave for this was related being able to overcome the wind on windy days. I have not done the calculation, but I believe that the top end speed on my Vanquish is in the 75 mph range or so (using a Evo25-12 and a 20x13 Xoar prop).
Teo
Teo
10-14-2014, 03:54 AM
#17
Thread Starter
No.
We never fly level flight for the complete length of the box, so how long it would take doesn't really mean anything. With the schedules and planes today, we are flying slower. Top speed is irrelevant as we never do it.
There was cop with a radar gun at our field last Saturday. I didn't radar my pattern model, but my sport models top speed was within 10 kmh of the speed I calculated it would reach. So I am confident the speeds I have listed above are pretty accurate.
We never fly level flight for the complete length of the box, so how long it would take doesn't really mean anything. With the schedules and planes today, we are flying slower. Top speed is irrelevant as we never do it.
There was cop with a radar gun at our field last Saturday. I didn't radar my pattern model, but my sport models top speed was within 10 kmh of the speed I calculated it would reach. So I am confident the speeds I have listed above are pretty accurate.
I do fly pattern my self so i know how its done. Reason for horizontal flight its much easier to asess the speed. When flying vertically its extemely difficult to asess the speed. Neither is it not much help to get from a GPS.
However, it seems that a speed around 100ft/sec pluss and minus will be a good average.
Regards
Last edited by DagTheElder; 10-14-2014 at 06:15 AM. Reason: Added ft/sec
10-14-2014, 04:34 AM
#18
Two years ago we were involved with a high school class science project using a Top Flight Dazzler thick winged 3D plane and a stock .46 two stroke. The plane was routinely clocked at 73 MPH using a 10x6 or 9x8 prop. And it appeared to be slow. As stated above I'd imagine most pattern planes are easily pushing 100 MPH.
10-14-2014, 05:04 AM
#19
Two years ago we were involved with a high school class science project using a Top Flight Dazzler thick winged 3D plane and a stock .46 two stroke. The plane was routinely clocked at 73 MPH using a 10x6 or 9x8 prop. And it appeared to be slow. As stated above I'd imagine most pattern planes are easily pushing 100 MPH.
Todays pattern ships are designed to fly slow. With the huge amount of power we have available there is no need to fly fast level flight so the momentum can carry the plane jn the verticals. They are propped and tuned to be able to throttle up as the vertical is started and still maintain the same speed. That set up doesn't provide high speeds.
10-14-2014, 06:28 AM
#20
Thread Starter
I doubt that.
Todays pattern ships are designed to fly slow. With the huge amount of power we have available there is no need to fly fast level flight so the momentum can carry the plane jn the verticals. They are propped and tuned to be able to throttle up as the vertical is started and still maintain the same speed. That set up doesn't provide high speeds.
Todays pattern ships are designed to fly slow. With the huge amount of power we have available there is no need to fly fast level flight so the momentum can carry the plane jn the verticals. They are propped and tuned to be able to throttle up as the vertical is started and still maintain the same speed. That set up doesn't provide high speeds.
You certainly are right, but there are a problem to fly very slow and that is the angle of Fuselage Deck (Datum Line) which will be something between 1 and 2° nose up.
So, shall you fly very slow the plane must be designed for that purpose.
Regards
Last edited by DagTheElder; 10-14-2014 at 06:31 AM.
10-17-2014, 12:07 PM
#21
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Top speed in level flight would depend on top RPM and pitch. I would say the speeds you are saying are too high.
In level flight through the pattern, I am at around 5/8 ths throttle which is about 4500 rpm. The pitch is 10", so doing the calculations speed is around 70 kmh.
Doing the calculations using my set up, ie. 7200 rpm, 10" pitch, top speed would be 110 kmh.
In level flight through the pattern, I am at around 5/8 ths throttle which is about 4500 rpm. The pitch is 10", so doing the calculations speed is around 70 kmh.
Doing the calculations using my set up, ie. 7200 rpm, 10" pitch, top speed would be 110 kmh.
(any erros?):
- 5/8 throttle gives a rmp of 4500 on ground
- Assuming the propeller used is an APC 20.5x 10, this gives a power output of 1.43 hp
- Airframe characteristics:
- wing area = S = 65 dm[SUP]2[/SUP]
- total drag coefficient (includes everything C[SUB]D0[/SUB], induced drag, trim drag,,) = C[SUB]D[/SUB]=0.04 (SWAG)
- Standard day, sea level: density = rho =1.225 kg/m[SUP]3[/SUP].
Since for a propeller the thrust is dependent on the flight speed, we end up with an equation as above, no closed form solution. But can be solved iteratively until thrust and speed matches.
- Assuming that the power output of the engine will be 1.43 hp, even if the rpm changes, note the throttle setting is not changed. Using the performance curves for the propeller an airspeed of 37 m/sec = 133 km/h = 83 mph is calculated. That is in straight and level flight at 5/8 throttle setting.
- The top speed is much higher than 37 m/sec. I plotted the hp output based on the data provided by UKpatternflyer in the thread “YS problem” and was scared. For a propeller with a pitch of 10” the top speed would be determined how fast the engine is able to rev. i.e. the power curve looks like. I does not have the performance deck of the engine.
DagtheElder: I know it does not answer your questions, you have to test (GPS) and do some reverse engineering . But our planes moves faster than we think.
Drac1: Assuming an advance ratio of 1.0 is very optimistic, at an advance ratio of about +/-0.75 the thrust is zero, please check APC's performance data.
Regards,
Arnstein
10-17-2014, 01:28 PM
#22
Just took the number provided added some assumption and here are the results
(any erros?):
Since for a propeller the thrust is dependent on the flight speed, we end up with an equation as above, no closed form solution. But can be solved iteratively until thrust and speed matches.
DagtheElder: I know it does not answer your questions, you have to test (GPS) and do some reverse engineering . But our planes moves faster than we think.
Drac1: Assuming an advance ratio of 1.0 is very optimistic, at an advance ratio of about +/-0.75 the thrust is zero, please check APC's performance data.
Regards,
Arnstein
(any erros?):
- 5/8 throttle gives a rmp of 4500 on ground
- Assuming the propeller used is an APC 20.5x 10, this gives a power output of 1.43 hp
- Airframe characteristics:
- wing area = S = 65 dm[SUP]2[/SUP]
- total drag coefficient (includes everything C[SUB]D0[/SUB], induced drag, trim drag,,) = C[SUB]D[/SUB]=0.04 (SWAG)
- Standard day, sea level: density = rho =1.225 kg/m[SUP]3[/SUP].
Since for a propeller the thrust is dependent on the flight speed, we end up with an equation as above, no closed form solution. But can be solved iteratively until thrust and speed matches.
- Assuming that the power output of the engine will be 1.43 hp, even if the rpm changes, note the throttle setting is not changed. Using the performance curves for the propeller an airspeed of 37 m/sec = 133 km/h = 83 mph is calculated. That is in straight and level flight at 5/8 throttle setting.
- The top speed is much higher than 37 m/sec. I plotted the hp output based on the data provided by UKpatternflyer in the thread “YS problem” and was scared. For a propeller with a pitch of 10” the top speed would be determined how fast the engine is able to rev. i.e. the power curve looks like. I does not have the performance deck of the engine.
DagtheElder: I know it does not answer your questions, you have to test (GPS) and do some reverse engineering . But our planes moves faster than we think.
Drac1: Assuming an advance ratio of 1.0 is very optimistic, at an advance ratio of about +/-0.75 the thrust is zero, please check APC's performance data.
Regards,
Arnstein
Last edited by drac1; 10-17-2014 at 01:32 PM.
10-17-2014, 10:46 PM
#24
Thread Starter
Hi Arnstein,
Thanks for input.
In my airspeed envelope calculations I have used 90-120 ft/sec and I get Horizontal stab incidence about -0,32° at 0,87° wing incidence. Further i get Horizontal stab incidence 0,00° at 120 ft/sec and adjusted Wing incidence Down to 0,65°.
So to do a proper calculation a set of valuable parameters will be necessary.
drac1
I will be greatfull for a radar gun test of airspeed.
Thank you both for Your interest!
Best regards
Thanks for input.
In my airspeed envelope calculations I have used 90-120 ft/sec and I get Horizontal stab incidence about -0,32° at 0,87° wing incidence. Further i get Horizontal stab incidence 0,00° at 120 ft/sec and adjusted Wing incidence Down to 0,65°.
So to do a proper calculation a set of valuable parameters will be necessary.
drac1
I will be greatfull for a radar gun test of airspeed.
Thank you both for Your interest!
Best regards
Last edited by DagTheElder; 10-18-2014 at 12:05 AM. Reason: Typo