New CARF P-51D Project
#101
Scale exhaust
ive made a number of scale exhaust systems for my Ziroli Corsair, P 51 and the 118" B 25.
ive used Stainless steel, 4130 steel tubing, copper tube fittings and totally fabricated from sheet Stainlees steel. All are relatively time consuming to build.
I like your P 51 system and the heat wrap. It sounds really cool.
With the two cylinder system as you have even though yours runs very well, I found that the multi engine (twin like yours) needed equal length pipes for each cylinder. Not really as " tuned pipes" but to provide equal exhaust flow for each motor/cylinder. It was quite pronounced on the big bomber. Even though I had to add a full 180 deg turn to equalize the length on the short side it improved performance of that motor so we could balance the speeds.
While yours seems to run very well it may help equalize temps on both cylinders to balance the pipe lengths. Just a thought.
The single cylinder P 51 had a 5.8 cu in 2 stroke motor. On this one I split the manifold at the exhaust port into two ports then and made two individual equal length pipes to the exit manifolds. This worked pretty well but we felt that it was a bit too heavy as we had to insulate both pipes as you did. It's very difficult to get tight bends in SS or steel so I made a single pipe to a smooth flowing " Y " and fabricated SS manifolds. This was all done with .028" sheet SS. I do TIG welding on hotrod stuff as well as for work but even so it was really difficult to weld this as it had to be back purged to make good welds. This system worked very well and was much lighter even with the heat wrap.
The Corsair was much easier as it needed considerable balance weight in the nose so weight wasn't an issue. I simply used copper tube fittings and for the " Y " pipe I sectioned a pair of elbows and welded them together. This gave a smooth and equal flow to both pipes. I never did add the smaller pipes as the radial has but that was the next step. This plane flew for 13 years without exhaust problems.
byron
ive made a number of scale exhaust systems for my Ziroli Corsair, P 51 and the 118" B 25.
ive used Stainless steel, 4130 steel tubing, copper tube fittings and totally fabricated from sheet Stainlees steel. All are relatively time consuming to build.
I like your P 51 system and the heat wrap. It sounds really cool.
With the two cylinder system as you have even though yours runs very well, I found that the multi engine (twin like yours) needed equal length pipes for each cylinder. Not really as " tuned pipes" but to provide equal exhaust flow for each motor/cylinder. It was quite pronounced on the big bomber. Even though I had to add a full 180 deg turn to equalize the length on the short side it improved performance of that motor so we could balance the speeds.
While yours seems to run very well it may help equalize temps on both cylinders to balance the pipe lengths. Just a thought.
The single cylinder P 51 had a 5.8 cu in 2 stroke motor. On this one I split the manifold at the exhaust port into two ports then and made two individual equal length pipes to the exit manifolds. This worked pretty well but we felt that it was a bit too heavy as we had to insulate both pipes as you did. It's very difficult to get tight bends in SS or steel so I made a single pipe to a smooth flowing " Y " and fabricated SS manifolds. This was all done with .028" sheet SS. I do TIG welding on hotrod stuff as well as for work but even so it was really difficult to weld this as it had to be back purged to make good welds. This system worked very well and was much lighter even with the heat wrap.
The Corsair was much easier as it needed considerable balance weight in the nose so weight wasn't an issue. I simply used copper tube fittings and for the " Y " pipe I sectioned a pair of elbows and welded them together. This gave a smooth and equal flow to both pipes. I never did add the smaller pipes as the radial has but that was the next step. This plane flew for 13 years without exhaust problems.
byron
#102
Thread Starter
My Feedback: (3)
I've been thinking of a design for a three into one header that's pretty basic. From each head up to a common larger tube then a flexible connection out to each side of the nose. Scale pipes optional but at least two working, one per side.
Like car manufacturers it would be great to tune the sound to get as much bass and rumble possible.
Like car manufacturers it would be great to tune the sound to get as much bass and rumble possible.
#103
That would be ok too. The hard part is getting flex tubing that fits the header close enough for a good weld. TIG welding flex tubing is very difficult as it is usually really thin. .015-.. 020". Fit has to be nearly ..0 It takes a very small electrode and .020 -.035 SS wire. It can be silicone bronze welded....TIG braised but even that is very tricky.
#105
We tried the dampening mounts but the motor simply moved around too much. It worked best to just solid mount it. I made aluminum replacements for the urathane soft mounts. I still used a slip joint in the headers however.
we also tried them on the B 25 but there was just too much moving around. So we solid mounted the motors. They actually ran smoother however I think there was just a different sound. The rpm remained the same.
byron
we also tried them on the B 25 but there was just too much moving around. So we solid mounted the motors. They actually ran smoother however I think there was just a different sound. The rpm remained the same.
byron
#106
I also found the engine to be very easy to start so I will not be using the starter, that way I will save about 1.5kg on the flying weight...maybe add it later when I get to know the plane..
H
#111
the hatch downside will make it possible to check the valves wihout removing the engine. but when you say ist easy , no Problem. looking Forward to see more :-)
#116
Yeah, plan on using it in conjuction with the temp sensor measurments for the two aft cylinders to control the opening, should be easy to make functional with my awsome Jeti radio
Things are coming togheter and I am starting to mount togheter the major bits to complete the plane...
Things are coming togheter and I am starting to mount togheter the major bits to complete the plane...
#117
Thread Starter
My Feedback: (3)
The working door is nice and yes if you’re actually ducting air thru the fuselage like mine then it will work. Have you made a duct tube like mine? If not then let me know and I could make one for you.
I plan to make a servo mount that goes on top of the duct with a control linkage to operate the door. I was not happy with the shape of the door, it’s too round, so I’m also modifying the door to look correct.
There is a company that makes a thermal controller for servos to move cowl flaps. I’ll post the info. It’s temp driven and can be controlled by the Tx.
I was debating on making the door operate based on throttle position or temp depending on how the engine ends up running.
I plan to make a servo mount that goes on top of the duct with a control linkage to operate the door. I was not happy with the shape of the door, it’s too round, so I’m also modifying the door to look correct.
There is a company that makes a thermal controller for servos to move cowl flaps. I’ll post the info. It’s temp driven and can be controlled by the Tx.
I was debating on making the door operate based on throttle position or temp depending on how the engine ends up running.
#118
Thread Starter
My Feedback: (3)
Oregon Scale Aviation made the controller called Thermacowl but the website is not working.
Im using temp telemetry on my TF Corsair with the DX18 but I haven’t tried to see if I can make a mix to open the door when a certain temp is reached.
Im using temp telemetry on my TF Corsair with the DX18 but I haven’t tried to see if I can make a mix to open the door when a certain temp is reached.
Last edited by Chris Nicastro; 12-22-2017 at 08:31 AM.
#119
The working door is nice and yes if you’re actually ducting air thru the fuselage like mine then it will work. Have you made a duct tube like mine? If not then let me know and I could make one for you.
I plan to make a servo mount that goes on top of the duct with a control linkage to operate the door. I was not happy with the shape of the door, it’s too round, so I’m also modifying the door to look correct.
There is a company that makes a thermal controller for servos to move cowl flaps. I’ll post the info. It’s temp driven and can be controlled by the Tx.
I was debating on making the door operate based on throttle position or temp depending on how the engine ends up running.
I plan to make a servo mount that goes on top of the duct with a control linkage to operate the door. I was not happy with the shape of the door, it’s too round, so I’m also modifying the door to look correct.
There is a company that makes a thermal controller for servos to move cowl flaps. I’ll post the info. It’s temp driven and can be controlled by the Tx.
I was debating on making the door operate based on throttle position or temp depending on how the engine ends up running.
#121
How are you guys solving getting the wing on without splitting it, I am planning on making this whole piece removable to be ab to lay the wing on in one piece without splitting it... what do you guys think?
#122
Thread Starter
My Feedback: (3)
I’m getting back to this project very soon.
The wing on my project will be two piece so I’m not sure how it affects the fuse to be one piece. My plan is to have it assembled and split as it’s placed on the fuse, then pushed together.
If you have the space to live with a huge wing then that’s cool.
I would suggest some additional tabs or keys to align the the scoop as well. Part of the design of the fuse in that area is to lock the wing in place. Now you have to carry that load into the fuse another way not just with the wing screws.
The wing on my project will be two piece so I’m not sure how it affects the fuse to be one piece. My plan is to have it assembled and split as it’s placed on the fuse, then pushed together.
If you have the space to live with a huge wing then that’s cool.
I would suggest some additional tabs or keys to align the the scoop as well. Part of the design of the fuse in that area is to lock the wing in place. Now you have to carry that load into the fuse another way not just with the wing screws.
#123
Had my second flight this afternoon, starting to get used to it anddialing in the engine and radio settings. Will be painting her this winter, fall...once all the bugs are removed and things are working nominally....
#125
Hi, Yes I like ramoser props very much but they will of course not be as effecient as a two blade, a two blade will give you more speed and be more powerful, but for me its the whole package thats important, therefore I think the airplane needs a fourblade.... Ramoser is good quality and ok priced spare blades if you are unlucky and chips one..also a very nice guy