Maj. Woody's X-Treme Jets F-4C Phantom
04-01-2018, 09:17 AM
#1051
Join Date: Jul 2004
Location: Saint Clair Shores, MI AZ
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Extreme F-4
I'm sure you'll enjoy the build once you get it. Waiting on the KingTech 120, electronic brake controller and the gear/door sequencer from Dirk. I also ordered better air lines from BVM. I used aluminum tape on the inside of the turkey feathers for heat disipation.
04-01-2018, 06:25 PM
#1054
If you add the afterburner lights they would really shine with that tape in there!
Make sure when you are installing your pipe to install it upside down from what the manual shows. Also cut the tabs off at the bottom as I show in the picture to keep the pipe lower, otherwise you will burn the tail. I had to also angle the tail cones by cutting them down and then shimming them as needed to fit the angle of the pipe.
Make sure when you are installing your pipe to install it upside down from what the manual shows. Also cut the tabs off at the bottom as I show in the picture to keep the pipe lower, otherwise you will burn the tail. I had to also angle the tail cones by cutting them down and then shimming them as needed to fit the angle of the pipe.
04-01-2018, 06:34 PM
#1055
Join Date: Jul 2004
Location: Saint Clair Shores, MI AZ
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Exhaust F-4
Thanks for the heads up on the tabs and inverting the exhaust. For right now I'm going for static display until I get the turbine. I had to move the elevator servos back from the original laser holes as everything wouldn't fit without bowing out the sides and difficult to put the bottom cover on. Have to make up new blocks to screw into also.
04-02-2018, 06:49 AM
#1057
If you add the afterburner lights they would really shine with that tape in there!
Make sure when you are installing your pipe to install it upside down from what the manual shows. Also cut the tabs off at the bottom as I show in the picture to keep the pipe lower, otherwise you will burn the tail. I had to also angle the tail cones by cutting them down and then shimming them as needed to fit the angle of the pipe.
Make sure when you are installing your pipe to install it upside down from what the manual shows. Also cut the tabs off at the bottom as I show in the picture to keep the pipe lower, otherwise you will burn the tail. I had to also angle the tail cones by cutting them down and then shimming them as needed to fit the angle of the pipe.
Bob
04-02-2018, 08:22 AM
#1058
When I did the maiden with the C model, I had the elevator right on the money, it also has inverted pipe. No trim was needed at any throttle setting. Turbine thrust angles seem to be more important than pipe angle, check out this picture of a giant scale F-15 (CSmith plans) in Germany, single pipe out the left nozzle! That is what Skymaster found out when they had the twins set on 0 degrees with the unfortunate modeler doing the single engine experimentation.
No problems going vertical or at any throttle setting with the F-15 set up as shown. The pipe in the F-15 is bent so that the bell is aligned with the turbine and then it goes straight out the back.
The reason I did the inverted pipe is because earlier in the thread MajWoody burned his tail when it was set up the stock way. The engine already has down thrust built into the mount, if you look at the pipe and the full scale F-4 you will see that inverted the pipe continues this line out the tail cones. I angled the tail cones to match the pipe and for a scale look. I have no idea why yours does not burn the tail, I'm just not going to take the chance and mine looks more scale, flies great. I am no expert however, so take what works with me with a grain of salt.
No problems going vertical or at any throttle setting with the F-15 set up as shown. The pipe in the F-15 is bent so that the bell is aligned with the turbine and then it goes straight out the back.
The reason I did the inverted pipe is because earlier in the thread MajWoody burned his tail when it was set up the stock way. The engine already has down thrust built into the mount, if you look at the pipe and the full scale F-4 you will see that inverted the pipe continues this line out the tail cones. I angled the tail cones to match the pipe and for a scale look. I have no idea why yours does not burn the tail, I'm just not going to take the chance and mine looks more scale, flies great. I am no expert however, so take what works with me with a grain of salt.
04-02-2018, 08:40 AM
#1059
Join Date: Jul 2004
Location: Saint Clair Shores, MI AZ
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Skymaster Extreme F-4
I will do the mod to save the tail feathers from burning. Thanks for all your help and insight. I am still going through all your past photos. Is there room for a drag chute in this F-4?
04-02-2018, 08:50 AM
#1060
So on mine, the engine rails are high enough that as long as the fuel tanks are spread out a bit, the turbine can go forward between them - as mine is mounted. That leaves the turbine significantly higher than the exhaust at the tailcones. The pipe has to be angled down in order for the beginning of the pipe to be aligned with the engine - or else the engine's exhaust will be hitting the side of the pipe and overheat it. Then, the ends of the pipe are *slightly* angled up to get the exhaust to be closer to the neutral thrust line - i.e., not be nose down.
With a mid-mounted engine, the angle of the exhaust is more important than the angle at which the engine is mounted. Angling the exhaust down too far is just like having vectored thrust with the nozzle pointed down. If your's dones't exhibit any nose down with thrust, then perhaps its not that much of an issue on this model, or your engine is mounted lower than mine.
With the pipe upright on mine, the exhaust still points down some, and if I mount the tailcones correctly, they still point down a bit - like the full scale. If I were to flip the pipe over, the downward angle would be larger than looks correct.
I did have a bit of bubbling on the skin of the bottom of the stab, but it was cosmetic only and easily fixed. I coated the bottom of the stab where the heat shield is on the full scale with BVM Heat Shield paint and repainted it. I haven't has any issues since. Maj. Woody had some bubbling of the paint on his as well, but I don't think it really "burnt" it.
Bob
With a mid-mounted engine, the angle of the exhaust is more important than the angle at which the engine is mounted. Angling the exhaust down too far is just like having vectored thrust with the nozzle pointed down. If your's dones't exhibit any nose down with thrust, then perhaps its not that much of an issue on this model, or your engine is mounted lower than mine.
With the pipe upright on mine, the exhaust still points down some, and if I mount the tailcones correctly, they still point down a bit - like the full scale. If I were to flip the pipe over, the downward angle would be larger than looks correct.
I did have a bit of bubbling on the skin of the bottom of the stab, but it was cosmetic only and easily fixed. I coated the bottom of the stab where the heat shield is on the full scale with BVM Heat Shield paint and repainted it. I haven't has any issues since. Maj. Woody had some bubbling of the paint on his as well, but I don't think it really "burnt" it.
Bob
04-02-2018, 08:52 AM
#1061
Bob
PS, I also have Sparrow and Sidewinder missiles and a centerline tank for mine as well - all modified from ones sized for the BVM F-4.
04-02-2018, 08:56 AM
#1062
It will be simple spring operated with a micro servo, I'll keep you posted.
04-02-2018, 09:19 AM
#1063
It's impossible to show in a picture, but the turbine down thrust is more than the pipe angle inverted. I don't think it's good for fiberglass to get hot all the time, but with my set up no extra work is needed. I felt the stabs after running the engine and they are not even warm.
You can see here how I trimmed the tabs, trim the bottom tabs and not the top. With the cones cut even, they only need to be shimmed 1/8" to get the right angle.
No vectored thrust, the angle of the pipe would have to be pretty severe to have a vectored thrust effect I would think. As you can see, my pipe inverted is not extreme at all and like I said is actually less down thrust than is built into the turbine mount.
You can see here how I trimmed the tabs, trim the bottom tabs and not the top. With the cones cut even, they only need to be shimmed 1/8" to get the right angle.
No vectored thrust, the angle of the pipe would have to be pretty severe to have a vectored thrust effect I would think. As you can see, my pipe inverted is not extreme at all and like I said is actually less down thrust than is built into the turbine mount.
04-02-2018, 05:33 PM
#1064
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Extreme Skymaster F-4
04-02-2018, 06:54 PM
#1065
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T-2C Buckeye
The standard size servos were to wide going in towards the back end of the jet. It was hard to get in causing a slight crack in the fuse. Bowed out the side of the fuse causing the elevator to bind on the side of the fuse. Using Spectrum HV High Torque A6150 servos. Now all is good.
04-03-2018, 08:00 AM
#1067
engine and pip mounting
Your setup is different than mine. My engine mounts further forward and higher. The result is that the pipe exits in what looks to me to be a scale amount of down thrust when installed right side up.
Regardless, it might be that a few degrees of down thrust at the pipe exhaust doesn't make mush difference in trim, but I'm sure that a few degrees of down thrust at the pipe exit doesn't make a more than a few degrees difference in how warm the aft fuselage and stabs get either...
Actually, I han't checked in awhile, but with the motor mounts glued in, I can't even get my pipe in upside down anymore. the Spacing between the former/mounts and the top of the fuselage is too tight. It also won't go any lower because its sitting on the aft wing tube...
Regardless, it might be that a few degrees of down thrust at the pipe exhaust doesn't make mush difference in trim, but I'm sure that a few degrees of down thrust at the pipe exit doesn't make a more than a few degrees difference in how warm the aft fuselage and stabs get either...
Actually, I han't checked in awhile, but with the motor mounts glued in, I can't even get my pipe in upside down anymore. the Spacing between the former/mounts and the top of the fuselage is too tight. It also won't go any lower because its sitting on the aft wing tube...
04-03-2018, 08:14 AM
#1069
My Feedback: (11)
The standard size servos were to wide going in towards the back end of the jet. It was hard to get in causing a slight crack in the fuse. Bowed out the side of the fuse causing the elevator to bind on the side of the fuse. Using Spectrum HV High Torque A6150 servos. Now all is good.
Jeff
04-03-2018, 08:45 AM
#1071
Bob, Your pipe is looks too high and is aimed straight back, wouldn't be the first time China got something wrong. 5 degrees of scale down thrust has no effect as far as I can tell, but again I only have 9 flights on this airframe.
My mounts are removable, so I can easily do whatever I want to do with the pipe or rear fuselage.
My setup does not make the stab warm and it does not burn the paint, not much more I can say on that, if you are happy that is all that matters though, I'm not changing mine either!
My mounts are removable, so I can easily do whatever I want to do with the pipe or rear fuselage.
Regardless, it might be that a few degrees of down thrust at the pipe exhaust doesn't make mush difference in trim, but I'm sure that a few degrees of down thrust at the pipe exit doesn't make a more than a few degrees difference in how warm the aft fuselage and stabs get either...
04-03-2018, 09:39 AM
#1073
Bob
Last edited by rhklenke; 04-03-2018 at 09:43 AM.
