O.S. GF40 4st gas
05-22-2014, 04:21 PM
#178
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May be this information will be also helpful as some reference:
I also have a plane with SAITO GF-30.
A week ago I have measured static trust with high accuracy.
The prop I used was APC 17x8.
The static trust at full throttle was in the range of 6.3 kg to 6.4 kg, which is close to 13 pounds.
This is only for the reference as measured trust will depend on engine condition, fuel mix, atmospheric pressure, prop and carb setup.
if you allow me for one advise then it is a good idea to purchase fish digital scale.
The model weight measuring and static thrust measuring will be a pleasure task with such scale.
I also have a plane with SAITO GF-30.
A week ago I have measured static trust with high accuracy.
The prop I used was APC 17x8.
The static trust at full throttle was in the range of 6.3 kg to 6.4 kg, which is close to 13 pounds.
This is only for the reference as measured trust will depend on engine condition, fuel mix, atmospheric pressure, prop and carb setup.
if you allow me for one advise then it is a good idea to purchase fish digital scale.
The model weight measuring and static thrust measuring will be a pleasure task with such scale.
06-03-2014, 11:41 AM
#180
Should be awesome, the GF 40 flys my 88 inch Tigermoth at 18 lbs on 1/4 throttle.
I'm running an 18x8 prop, still running it in, but expect to be at a 19x8 when it's run in, maybe a 20x8, but my experience has been to not load them up too much, let them rev in the range given by the manufacturer (OS).
I did at one stage have too big a prop, didn't sound nice or run well.
I'm running an 18x8 prop, still running it in, but expect to be at a 19x8 when it's run in, maybe a 20x8, but my experience has been to not load them up too much, let them rev in the range given by the manufacturer (OS).
I did at one stage have too big a prop, didn't sound nice or run well.
http://www.youtube.com/watch?v=BSayODBM1dA Installation details here: http://www.rcuniverse.com/forum/arf-...l#post11785097
Nice motor, still running in (sounds blubbery in the video). Oil is Castrol 2T Synthetic @ 32:1.
Last edited by hpergm; 06-04-2014 at 08:16 AM.
06-04-2014, 07:18 AM
#181
Senior Member
May be this information will be also helpful as some reference:
I also have a plane with SAITO GF-30.
A week ago I have measured static trust with high accuracy.
The prop I used was APC 17x8.
The static trust at full throttle was in the range of 6.3 kg to 6.4 kg, which is close to 13 pounds.
This is only for the reference as measured trust will depend on engine condition, fuel mix, atmospheric pressure, prop and carb setup.
if you allow me for one advise then it is a good idea to purchase fish digital scale.
The model weight measuring and static thrust measuring will be a pleasure task with such scale.
I also have a plane with SAITO GF-30.
A week ago I have measured static trust with high accuracy.
The prop I used was APC 17x8.
The static trust at full throttle was in the range of 6.3 kg to 6.4 kg, which is close to 13 pounds.
This is only for the reference as measured trust will depend on engine condition, fuel mix, atmospheric pressure, prop and carb setup.
if you allow me for one advise then it is a good idea to purchase fish digital scale.
The model weight measuring and static thrust measuring will be a pleasure task with such scale.
11-07-2015, 07:03 PM
#184
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I have a GF40 and when the engine is running I get fluttering on all servos. This has never happened to me before with OG GT 33's GT 22 or Dle 35 & 55. I think it may be interference from the CDI ( which is well placed away from servos, rex etc) and the rex and electrical set up is exactly the same as all my other planes. A mate at my field suggested that I earth/ground the CDI box to the engine. Any suggestions? BTW, I use ferrite's on the ignition lead from the CDI to the kill switch, as with all my other craft.
Last edited by CNXRC; 11-07-2015 at 07:28 PM.
11-07-2015, 07:38 PM
#185
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Your flattering may be due to just mechanical oscillation and specific aileron size/shape/weight as well as linkage looseness and servo overcompensation.
the vibration from 4-stroke engine is also different.
the strongest shake if happening with 2 times less frequency, which make airframe shake harder.
with OSGT33 the shaking is happening more often and mechanically ailerons are not able to get in oscillation mode. The weight of them is not allow them to get in resonance with servo overcompensation .
Just my personal opinion and you may ignore it.
the vibration from 4-stroke engine is also different.
the strongest shake if happening with 2 times less frequency, which make airframe shake harder.
with OSGT33 the shaking is happening more often and mechanically ailerons are not able to get in oscillation mode. The weight of them is not allow them to get in resonance with servo overcompensation .
Just my personal opinion and you may ignore it.
11-07-2015, 08:26 PM
#186
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Yes, I probably haven't described the effect very well. What happens is that one aileron, flap or elevator will move up or down and then some other surface will move. its not an oscillation as you would have with vibration. Its more like a twitch on one control surface. May be one elevator will move up and one flap go down etc. Ghostly stuff!
11-07-2015, 09:50 PM
#187
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This to me reeks of interference . I think your gonna have to go through everything electrical . Leads , plugs ,switches , servos , kill switches ,batteries , ign and hall sensor , connections of all sorts etc etc . Anything that even sniffs current . Good luck from the pope
11-08-2015, 05:38 AM
#188
This to me reeks of interference . I think your gonna have to go through everything electrical . Leads , plugs ,switches , servos , kill switches ,batteries , ign and hall sensor , connections of all sorts etc etc . Anything that even sniffs current . Good luck from the pope
Karol
11-08-2015, 07:35 PM
#190
Senior Member
I have a GF40 and when the engine is running I get fluttering on all servos. This has never happened to me before with OG GT 33's GT 22 or Dle 35 & 55. I think it may be interference from the CDI ( which is well placed away from servos, rex etc) and the rex and electrical set up is exactly the same as all my other planes. A mate at my field suggested that I earth/ground the CDI box to the engine. Any suggestions? BTW, I use ferrite's on the ignition lead from the CDI to the kill switch, as with all my other craft.
What type of radio are you using? Have you separated the CDI module and the ignition cable from the RX as much as possible? Is the plug socket secured all the way?
08-28-2016, 05:14 PM
#191
GF40 owners,
I've got an OS GF40 on a WWI biplane with an 18x8 propeller. It idles nice, and performance is good from 1/2 throttle on up to full throttle. Around 1/3 throttle, it burbles quite a bit. By that I mean, the rpm is unstable and the engine sounds like it is missing in this mid-range throttle setting. I concluded that this meant the low speed needle was rich, so I experimented with leaning that out. It helped a little, but then I get into the issue where it is too lean to avoid flame-out when I punch it to full throttle. At the time I did this experiment, the engine was still very new, probably only had 3 flights on it. Did any of you encounter a similar instability around 1/3 throttle? Does it go away with additional break-in time?
thanks,
Greg
I've got an OS GF40 on a WWI biplane with an 18x8 propeller. It idles nice, and performance is good from 1/2 throttle on up to full throttle. Around 1/3 throttle, it burbles quite a bit. By that I mean, the rpm is unstable and the engine sounds like it is missing in this mid-range throttle setting. I concluded that this meant the low speed needle was rich, so I experimented with leaning that out. It helped a little, but then I get into the issue where it is too lean to avoid flame-out when I punch it to full throttle. At the time I did this experiment, the engine was still very new, probably only had 3 flights on it. Did any of you encounter a similar instability around 1/3 throttle? Does it go away with additional break-in time?
thanks,
Greg
08-28-2016, 10:19 PM
#192
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I was very remiss in not following up on the helpful comments here so my apologies. I ended up putting a ferrite on the battery lead of the CDI and all the problems went away. A simple and quick fix luckily.
08-28-2016, 11:17 PM
#193
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Eindecker,
Mine has 13 flights and ~4.5 liters fuel through and its still breaking in. You will notice gradual improvement, it needs its sweet time
I was at an event in June and heard a nice-sounding GF 40 on a H9 Tiger Moth - the owner (HPergm, see post #180 above) told me it took 6 months of occasional flying to fully break in
Mine has 13 flights and ~4.5 liters fuel through and its still breaking in. You will notice gradual improvement, it needs its sweet time
I was at an event in June and heard a nice-sounding GF 40 on a H9 Tiger Moth - the owner (HPergm, see post #180 above) told me it took 6 months of occasional flying to fully break in
Last edited by w1nd6urfa; 08-28-2016 at 11:21 PM.
08-31-2016, 04:18 PM
#194
Thanks for the advice! That's what I needed to hear. I'll try leaning out the low end a little after another half gallon has gone through it.
Greg
Greg
Eindecker,
Mine has 13 flights and ~4.5 liters fuel through and its still breaking in. You will notice gradual improvement, it needs its sweet time
I was at an event in June and heard a nice-sounding GF 40 on a H9 Tiger Moth - the owner (HPergm, see post #180 above) told me it took 6 months of occasional flying to fully break in
Mine has 13 flights and ~4.5 liters fuel through and its still breaking in. You will notice gradual improvement, it needs its sweet time
I was at an event in June and heard a nice-sounding GF 40 on a H9 Tiger Moth - the owner (HPergm, see post #180 above) told me it took 6 months of occasional flying to fully break in
09-04-2016, 11:21 AM
#195
Did some more test running at home & then more flights at the field. I did a repeat of the low-speed needle tuning exercise and have now successfully eliminated the rough sounding burble in the mid-range throttle position. It runs smooth across the whole rpm band. Really good running engine. Like you said, it needed its break-in time.
04-23-2017, 08:16 PM
#197
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Not exactly an aftermarket solution, but worked for me: a 90-deg manifold for the OS 200 allowed me to completely hide the GF40 exhaust in the cowl of a 80" Spitfire. Caution: use baffles and grilles for cooling!
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Last edited by w1nd6urfa; 04-23-2017 at 08:18 PM.