Need more pull not speed.. help!
08-13-2006 | 06:13 PM
#1
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From: Huntingtown,
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Need more pull not speed.. help!
I have a SeaGull Edge with an OS 1.08 currently running a 15X6 prop. The problem is the speed is too fast for aerobatics. I currently need about 1/3 throttle for a comfortable speed but it wil not complete a big loop without stalling. What should i do to increase rpm to gain more Pulling power rather than speed? Larger proper or lower pitch or both?
08-13-2006 | 06:52 PM
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From: PerthWA, AUSTRALIA
RE: Need more pull not speed.. help!
Yes - you answered it right
Bigger prop with lower pitch - maybe an APC 16/4 W. This seems to be a pretty popular prop if you want to do 3d type maneuvres.
Bigger prop with lower pitch - maybe an APC 16/4 W. This seems to be a pretty popular prop if you want to do 3d type maneuvres.
08-14-2006 | 06:03 PM
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From: Buckingham, UNITED KINGDOM
RE: Need more pull not speed.. help!
Remove heavy poor performing Saito 150 and replace with YS110, get lightness, torque and throttling. You could stick almost any prop on it and it would still loop your edge np.
Ok im being facetious...the saito is a nice engine too i jsut love YS and couldnt resist...
Ok im being facetious...the saito is a nice engine too i jsut love YS and couldnt resist...
08-14-2006 | 06:29 PM
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From: Huntingtown,
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RE: Need more pull not speed.. help!
Thanks,
While i understand the need for throttle management, i also know that the right prop goes a long way towards improving performance. Thanks for the help. Now i need to find some 16X4.
While i understand the need for throttle management, i also know that the right prop goes a long way towards improving performance. Thanks for the help. Now i need to find some 16X4.
08-14-2006 | 09:51 PM
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From: New Richmond,
WI
RE: Need more pull not speed.. help!
ORIGINAL: LearnedInUk
I have a SeaGull Edge with an OS 1.08 currently running a 15X6 prop. The problem is the speed is too fast for aerobatics. I currently need about 1/3 throttle for a comfortable speed but it wil not complete a big loop without stalling. What should i do to increase rpm to gain more Pulling power rather than speed? Larger proper or lower pitch or both?
I have a SeaGull Edge with an OS 1.08 currently running a 15X6 prop. The problem is the speed is too fast for aerobatics. I currently need about 1/3 throttle for a comfortable speed but it wil not complete a big loop without stalling. What should i do to increase rpm to gain more Pulling power rather than speed? Larger proper or lower pitch or both?
How heavy is your Edge and what does your 1.08 turn your 15x6? It should pull very well if the plane is only around 8-9 pounds.
The 15x6 is a bad prop for the OS1.08. I say this because my OS.91 would turn a 15x6apc 10,200 and my OS108 would only pull the same prop another 300RPM. Start to load it in the 9's though, and it will out power the .91FX significantly. The best prop I have found for the OS108 is a good Skorepa 17x6(~9,100). Next a 17x6 apc or 16x6 apc. The 17x4W works OK also. My OS108 on pitts muffler has the same power on cheap 15% as my YS110 did on 30%(APC 16x6 ~9,500 for flying).
Well today was not a good fly day—too rainy and windy, but I did go out and get some thrust figures. The test was with a F90 with OS 108FSR , Jec pitts muffler, restrictor sleeve removed from the carb and VP30 pump. Fuel used was Cool Power 15%. Temp 51° Humidity 76% and dupoint was 44°. I used a Rapalla fishing scale that calibrates within 1oz at 10 and 15 pounds. Elevation is at about 300 feet.
I tried six different props and to my surprise max thrust was very close between them. The props are shown below in the picture and are ordered left to right lowest to highest thrust. My measurements were rmp at 10 pounds (about hovering rpm) of thrust and rmp at max rpm/thrust.
Prop RPM at 10 pounds Max RPM& Thrust
15 x6 apc 8,900rpm 10,600 – 13.7 pounds
16 x6 zing not measured 9400- 14.6 pounds
18x8n apc 6,400 8200- 14.9 pounds
16 x5 c zing 7,900 9800- 15.1 pounds
16 x6 apc 7,700 9520- 15.2 pounds
17 x6 apc 7,100 9,200- 15.5 pounds
I am extremely happy with the way the motor runs and transition is outstanding. I made a recording of it at the end when I had the 16 x 6 zinger on. Anyone curious to how fast this 2 stoke transitions please email me and I will send the wave file to you.
I tried six different props and to my surprise max thrust was very close between them. The props are shown below in the picture and are ordered left to right lowest to highest thrust. My measurements were rmp at 10 pounds (about hovering rpm) of thrust and rmp at max rpm/thrust.
Prop RPM at 10 pounds Max RPM& Thrust
15 x6 apc 8,900rpm 10,600 – 13.7 pounds
16 x6 zing not measured 9400- 14.6 pounds
18x8n apc 6,400 8200- 14.9 pounds
16 x5 c zing 7,900 9800- 15.1 pounds
16 x6 apc 7,700 9520- 15.2 pounds
17 x6 apc 7,100 9,200- 15.5 pounds
I am extremely happy with the way the motor runs and transition is outstanding. I made a recording of it at the end when I had the 16 x 6 zinger on. Anyone curious to how fast this 2 stoke transitions please email me and I will send the wave file to you.
08-17-2006 | 03:39 PM
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From: Huntingtown,
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RE: Need more pull not speed.. help!
ORIGINAL: STG
You cannot expect to keep the throttle in one position and keep the plane at a constant speed as you are going thru a large loop. Do you mean that you are not increasing your throttle when you are climbing and not decreasing your throttle when descending?
You cannot expect to keep the throttle in one position and keep the plane at a constant speed as you are going thru a large loop. Do you mean that you are not increasing your throttle when you are climbing and not decreasing your throttle when descending?
How heavy is your Edge and what does your 1.08 turn your 15x6? It should pull very well if the plane is only around 8-9 pounds.
I will get a few props and see how it works out.
Thanks
08-17-2006 | 03:47 PM
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From: Buckingham, UNITED KINGDOM
RE: Need more pull not speed.. help!
Essentially your prop is a screw turning through the air, therefore, I have a rule of tumb that has always worked for me:
more diameter = more mass of air being driven backwards at speed x = MORE THRUST
more pitch = mass of air being driven backwards more quickly (at speed pitch n x rpm minus losses (drag, efficiency etc) = MORE SPEED
Now it doesnt quite work exactly like that, ie, my Jetcat P160 is a very small diameter fan but boy does it produce alot of thrust! (like 38lbs, but then it is rotating at 125k rpm) Conversely in glider electroslot/F5B competitions which i participate in the guys set up the gliders so that pitch matches the wing 'flying speed', then just go for the max diameter possible to acheive massive climb rates, like 2000ft per min and up but for best efficiency go for the lowest possible rpm (3k+)!
This isnt strictly true but does generally work. So if you are lacking thrust which it sounds like you are (no 'bite'). Go for bigger diameter and minimum pitch at which the aircraft will comfortably fly your schedule at.
more diameter = more mass of air being driven backwards at speed x = MORE THRUST
more pitch = mass of air being driven backwards more quickly (at speed pitch n x rpm minus losses (drag, efficiency etc) = MORE SPEED
Now it doesnt quite work exactly like that, ie, my Jetcat P160 is a very small diameter fan but boy does it produce alot of thrust! (like 38lbs, but then it is rotating at 125k rpm) Conversely in glider electroslot/F5B competitions which i participate in the guys set up the gliders so that pitch matches the wing 'flying speed', then just go for the max diameter possible to acheive massive climb rates, like 2000ft per min and up but for best efficiency go for the lowest possible rpm (3k+)!
This isnt strictly true but does generally work. So if you are lacking thrust which it sounds like you are (no 'bite'). Go for bigger diameter and minimum pitch at which the aircraft will comfortably fly your schedule at.
08-17-2006 | 04:04 PM
#13
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RE: Need more pull not speed.. help!
ORIGINAL: LearnedInUk
No what i mean is that even when increasing power the plane seems to gain too much speed vs pull. I need more "bite"
came in about 8.8lbs
I will get a few props and see how it works out.
Thanks
ORIGINAL: STG
You cannot expect to keep the throttle in one position and keep the plane at a constant speed as you are going thru a large loop. Do you mean that you are not increasing your throttle when you are climbing and not decreasing your throttle when descending?
You cannot expect to keep the throttle in one position and keep the plane at a constant speed as you are going thru a large loop. Do you mean that you are not increasing your throttle when you are climbing and not decreasing your throttle when descending?
How heavy is your Edge and what does your 1.08 turn your 15x6? It should pull very well if the plane is only around 8-9 pounds.
I will get a few props and see how it works out.
Thanks
Let us know the outcome...[8D]
08-17-2006 | 06:52 PM
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From: New Richmond,
WI
RE: Need more pull not speed.. help!
ORIGINAL: LearnedInUk
No what i mean is that even when increasing power the plane seems to gain too much speed vs pull. I need more "bite"
ORIGINAL: STG
You cannot expect to keep the throttle in one position and keep the plane at a constant speed as you are going thru a large loop. Do you mean that you are not increasing your throttle when you are climbing and not decreasing your throttle when descending?
You cannot expect to keep the throttle in one position and keep the plane at a constant speed as you are going thru a large loop. Do you mean that you are not increasing your throttle when you are climbing and not decreasing your throttle when descending?
....but it wil not complete a big loop without stalling.
When I thrust tested the 17x4W it turned the same RPM as the 16x6apc and about 1/2 pound less thrust (~14.5pounds with 17x4W and 15 pounds with the 16x6apc).
08-26-2006 | 09:14 AM
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From: Huntingtown,
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RE: Need more pull not speed.. help!
MikeEast Hit the nail on the head. His description is exactly what my issue is. I just put a 16X4 APC on it, might need taller gear now, and will test it out today or Sunday.
