Tamjets A4 Tank issue
04-02-2012 | 09:19 PM
#1
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Tamjets A4 Tank issue
I am slowly building a Tam A4 skyhawk and have an issue with the fuel tanks.
For those not familiar with the tank layout in this jet, it comprises of two saddle tanks, a main tank fitted flat on the belly of the fuselage in front of the turbine and a UAT. The saddle tanks and main tank have been drilled by the munufacturer to have the tank fittings on one side of the fuel tank as opposed to the middle. The problem is that the clunk at that position will have to face to the extreme bottom of the opposite side of the tank and will not move when inverted as its too long. If i make it shorter it will only draw fuel to about half the capacity of the tank.
The same issue with the main tank, only the problem with this is that it will not draw fuel when the aircraft is banking.
Look at the pictures below (of the details4scale fuel tanks which are the same design as the factory ones).
Any advise welcome as to how I should make the fittings work.
L
For those not familiar with the tank layout in this jet, it comprises of two saddle tanks, a main tank fitted flat on the belly of the fuselage in front of the turbine and a UAT. The saddle tanks and main tank have been drilled by the munufacturer to have the tank fittings on one side of the fuel tank as opposed to the middle. The problem is that the clunk at that position will have to face to the extreme bottom of the opposite side of the tank and will not move when inverted as its too long. If i make it shorter it will only draw fuel to about half the capacity of the tank.
The same issue with the main tank, only the problem with this is that it will not draw fuel when the aircraft is banking.
Look at the pictures below (of the details4scale fuel tanks which are the same design as the factory ones).
Any advise welcome as to how I should make the fittings work.
L
04-03-2012 | 10:45 PM
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From: Mt. Vernon, IL
RE: Tamjets A4 Tank issue
This won't be an issue unless you are going to fly inverted for long periods of time. The saddle tanks may be exposed to air while inverted but will resume flowing fuel while upright.
04-03-2012 | 11:40 PM
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RE: Tamjets A4 Tank issue
ORIGINAL: fw190pilot
This won't be an issue unless you are going to fly inverted for long periods of time. The saddle tanks may be exposed to air while inverted but will resume flowing fuel while upright.
This won't be an issue unless you are going to fly inverted for long periods of time. The saddle tanks may be exposed to air while inverted but will resume flowing fuel while upright.
Make sure to plumb in series however this way the third tanks will be full for ages before any issues could happen and then this will be looked after by the UAT
Bert
04-04-2012 | 02:32 AM
#5
My Feedback: (28)
RE: Tamjets A4 Tank issue
I had my saddles plumbed parallel and those fed the main bottom tank which is shaped in a way you will get full clunk travel. While inverted, if the saddle tanks sucked air, your main tank will feed properly. When right side up, the saddles will continue to draw fuel normally. In my A-4 I was able to use all the fuel reliably with no issues. I sold the A-4 with over 100 perfect flights on it. Good Luck!
08-12-2012 | 03:12 PM
#6
RE: Tamjets A4 Tank issue
Hi Loukos,
Since you say you are slowly building your A-4, maybe I can also still provide some useful information as you may still be building. I still have my Tamjets A-4. I am using a Wren Supersport for power, appx. 18 pounds thrust. The Wren actually uses less fuel per minute than a P-60 but I wanted long flight times and had extra thrust to carry more fuel so I added a 16 ounce header tank in addition to the stock fuel.
My tank plumbing: I plumbed the saddle tanks to feed to the main in parallel, and then the main feeds to the aux and to the UAT in series. After a flight I never have any fuel left in the saddles, no fuel in the main, I've used about 5-7 ounces out of the AUX and there is absolutely no air in the UAT. It's good to keep the main tank full as long as you can if you are not running an aux tank (not stock - only a few guys I know are running aux tanks). The main tank form factor is long, wide and short so it's possible to uncover the klunk when it get's close to empty if you put some side load (yaw) tot he aircraft and that's always happening with RC planes. So I wanted to keep it full for as long as I could that's why I went with parallel saddle tanks and then series feed from the main onward.
So my fuel is parallel - series. Parallel feed from both saddle tanks at once - they draw air from the main vent line fed to the bottom of the fuse into a "T" fitting and then into the vents of each saddle tank - the fuel for the saddles each feed from their klunks to the individual vent fitting on the main tank vent lines (details 4 scale main tank has 2 vent tubes, 1 on each side). Then the main tank feeds from it's main klunk pickup, and up into the Aux tank that is mounted between the saddle tanks. My aux tank used to be 16 ounces. Now this season I changed to 12 ounces as I never used enough of the aux tank fuel and was landing "fat" on fuel all the time so I figured I would just save a few ounces of flight weight and keep my timer as it is - 7 minutes from full thrust application on takeoff to desired gear pass and landing when the beeper is going off. That's plenty. Anyhow, the "Aux" tank then feeds directly to the UAT. I have the UAT just aft of the equipment tray in the nose on the right side of the jet, just forward of the the right inlet. I consider the UAT to be unusable fuel and the A-4 is balanced with empty tanks and a full UAT. I don't need any lead in the nose at all as the UAT helps and also the equipment (2X 2300mah A123 packs for RX, fuel pump, 3200mah ECU pack, solenoids...) it's all mounted in the nose cone in a fixed equipment tray. It's actually a pretty light weight setup for a turbine with no lead ballast.
I've been extremely happy with the fuel feed performance this way and I appreciate the extra flight time. Compared to the stock fuel an extra aux tank can give you the extra time to clean out the main tank slowly in between air bubbles when it get's nearly empty while sucking off a nearly full aux tank and the UAT never ever get's close to having an air bubble in it so fuel delivery is guaranteed. Because I went down in weight a little with my updated aux tank and I have everything disassembled to change the fuel lines and such (annual inspection during the hot dry months as I don't fly turbines at home this time of year) - I'm using that as an excuse to finally install my smoke tank. It's a center line pylon tank with the pump and the smoke tank inside the "external tank fairing" and completely removable when not desired - so as to keep the jet as a clean, light sport jet when I'm not smoking.
Since you say you are slowly building your A-4, maybe I can also still provide some useful information as you may still be building. I still have my Tamjets A-4. I am using a Wren Supersport for power, appx. 18 pounds thrust. The Wren actually uses less fuel per minute than a P-60 but I wanted long flight times and had extra thrust to carry more fuel so I added a 16 ounce header tank in addition to the stock fuel.
My tank plumbing: I plumbed the saddle tanks to feed to the main in parallel, and then the main feeds to the aux and to the UAT in series. After a flight I never have any fuel left in the saddles, no fuel in the main, I've used about 5-7 ounces out of the AUX and there is absolutely no air in the UAT. It's good to keep the main tank full as long as you can if you are not running an aux tank (not stock - only a few guys I know are running aux tanks). The main tank form factor is long, wide and short so it's possible to uncover the klunk when it get's close to empty if you put some side load (yaw) tot he aircraft and that's always happening with RC planes. So I wanted to keep it full for as long as I could that's why I went with parallel saddle tanks and then series feed from the main onward.
So my fuel is parallel - series. Parallel feed from both saddle tanks at once - they draw air from the main vent line fed to the bottom of the fuse into a "T" fitting and then into the vents of each saddle tank - the fuel for the saddles each feed from their klunks to the individual vent fitting on the main tank vent lines (details 4 scale main tank has 2 vent tubes, 1 on each side). Then the main tank feeds from it's main klunk pickup, and up into the Aux tank that is mounted between the saddle tanks. My aux tank used to be 16 ounces. Now this season I changed to 12 ounces as I never used enough of the aux tank fuel and was landing "fat" on fuel all the time so I figured I would just save a few ounces of flight weight and keep my timer as it is - 7 minutes from full thrust application on takeoff to desired gear pass and landing when the beeper is going off. That's plenty. Anyhow, the "Aux" tank then feeds directly to the UAT. I have the UAT just aft of the equipment tray in the nose on the right side of the jet, just forward of the the right inlet. I consider the UAT to be unusable fuel and the A-4 is balanced with empty tanks and a full UAT. I don't need any lead in the nose at all as the UAT helps and also the equipment (2X 2300mah A123 packs for RX, fuel pump, 3200mah ECU pack, solenoids...) it's all mounted in the nose cone in a fixed equipment tray. It's actually a pretty light weight setup for a turbine with no lead ballast.
I've been extremely happy with the fuel feed performance this way and I appreciate the extra flight time. Compared to the stock fuel an extra aux tank can give you the extra time to clean out the main tank slowly in between air bubbles when it get's nearly empty while sucking off a nearly full aux tank and the UAT never ever get's close to having an air bubble in it so fuel delivery is guaranteed. Because I went down in weight a little with my updated aux tank and I have everything disassembled to change the fuel lines and such (annual inspection during the hot dry months as I don't fly turbines at home this time of year) - I'm using that as an excuse to finally install my smoke tank. It's a center line pylon tank with the pump and the smoke tank inside the "external tank fairing" and completely removable when not desired - so as to keep the jet as a clean, light sport jet when I'm not smoking.
08-12-2012 | 09:32 PM
#7
Thread Starter
My Feedback: (2)
RE: Tamjets A4 Tank issue
ORIGINAL: Eddie P
Hi Loukos,
Since you say you are slowly building your A-4, maybe I can also still provide some useful information as you may still be building. I still have my Tamjets A-4. I am using a Wren Supersport for power, appx. 18 pounds thrust. The Wren actually uses less fuel per minute than a P-60 but I wanted long flight times and had extra thrust to carry more fuel so I added a 16 ounce header tank in addition to the stock fuel.
My tank plumbing: I plumbed the saddle tanks to feed to the main in parallel, and then the main feeds to the aux and to the UAT in series. After a flight I never have any fuel left in the saddles, no fuel in the main, I've used about 5-7 ounces out of the AUX and there is absolutely no air in the UAT. It's good to keep the main tank full as long as you can if you are not running an aux tank (not stock - only a few guys I know are running aux tanks). The main tank form factor is long, wide and short so it's possible to uncover the klunk when it get's close to empty if you put some side load (yaw) tot he aircraft and that's always happening with RC planes. So I wanted to keep it full for as long as I could that's why I went with parallel saddle tanks and then series feed from the main onward.
So my fuel is parallel - series. Parallel feed from both saddle tanks at once - they draw air from the main vent line fed to the bottom of the fuse into a ''T'' fitting and then into the vents of each saddle tank - the fuel for the saddles each feed from their klunks to the individual vent fitting on the main tank vent lines (details 4 scale main tank has 2 vent tubes, 1 on each side). Then the main tank feeds from it's main klunk pickup, and up into the Aux tank that is mounted between the saddle tanks. My aux tank used to be 16 ounces. Now this season I changed to 12 ounces as I never used enough of the aux tank fuel and was landing ''fat'' on fuel all the time so I figured I would just save a few ounces of flight weight and keep my timer as it is - 7 minutes from full thrust application on takeoff to desired gear pass and landing when the beeper is going off. That's plenty. Anyhow, the ''Aux'' tank then feeds directly to the UAT. I have the UAT just aft of the equipment tray in the nose on the right side of the jet, just forward of the the right inlet. I consider the UAT to be unusable fuel and the A-4 is balanced with empty tanks and a full UAT. I don't need any lead in the nose at all as the UAT helps and also the equipment (2X 2300mah A123 packs for RX, fuel pump, 3200mah ECU pack, solenoids...) it's all mounted in the nose cone in a fixed equipment tray. It's actually a pretty light weight setup for a turbine with no lead ballast.
I've been extremely happy with the fuel feed performance this way and I appreciate the extra flight time. Compared to the stock fuel an extra aux tank can give you the extra time to clean out the main tank slowly in between air bubbles when it get's nearly empty while sucking off a nearly full aux tank and the UAT never ever get's close to having an air bubble in it so fuel delivery is guaranteed. Because I went down in weight a little with my updated aux tank and I have everything disassembled to change the fuel lines and such (annual inspection during the hot dry months as I don't fly turbines at home this time of year) - I'm using that as an excuse to finally install my smoke tank. It's a center line pylon tank with the pump and the smoke tank inside the ''external tank fairing'' and completely removable when not desired - so as to keep the jet as a clean, light sport jet when I'm not smoking.
Hi Loukos,
Since you say you are slowly building your A-4, maybe I can also still provide some useful information as you may still be building. I still have my Tamjets A-4. I am using a Wren Supersport for power, appx. 18 pounds thrust. The Wren actually uses less fuel per minute than a P-60 but I wanted long flight times and had extra thrust to carry more fuel so I added a 16 ounce header tank in addition to the stock fuel.
My tank plumbing: I plumbed the saddle tanks to feed to the main in parallel, and then the main feeds to the aux and to the UAT in series. After a flight I never have any fuel left in the saddles, no fuel in the main, I've used about 5-7 ounces out of the AUX and there is absolutely no air in the UAT. It's good to keep the main tank full as long as you can if you are not running an aux tank (not stock - only a few guys I know are running aux tanks). The main tank form factor is long, wide and short so it's possible to uncover the klunk when it get's close to empty if you put some side load (yaw) tot he aircraft and that's always happening with RC planes. So I wanted to keep it full for as long as I could that's why I went with parallel saddle tanks and then series feed from the main onward.
So my fuel is parallel - series. Parallel feed from both saddle tanks at once - they draw air from the main vent line fed to the bottom of the fuse into a ''T'' fitting and then into the vents of each saddle tank - the fuel for the saddles each feed from their klunks to the individual vent fitting on the main tank vent lines (details 4 scale main tank has 2 vent tubes, 1 on each side). Then the main tank feeds from it's main klunk pickup, and up into the Aux tank that is mounted between the saddle tanks. My aux tank used to be 16 ounces. Now this season I changed to 12 ounces as I never used enough of the aux tank fuel and was landing ''fat'' on fuel all the time so I figured I would just save a few ounces of flight weight and keep my timer as it is - 7 minutes from full thrust application on takeoff to desired gear pass and landing when the beeper is going off. That's plenty. Anyhow, the ''Aux'' tank then feeds directly to the UAT. I have the UAT just aft of the equipment tray in the nose on the right side of the jet, just forward of the the right inlet. I consider the UAT to be unusable fuel and the A-4 is balanced with empty tanks and a full UAT. I don't need any lead in the nose at all as the UAT helps and also the equipment (2X 2300mah A123 packs for RX, fuel pump, 3200mah ECU pack, solenoids...) it's all mounted in the nose cone in a fixed equipment tray. It's actually a pretty light weight setup for a turbine with no lead ballast.
I've been extremely happy with the fuel feed performance this way and I appreciate the extra flight time. Compared to the stock fuel an extra aux tank can give you the extra time to clean out the main tank slowly in between air bubbles when it get's nearly empty while sucking off a nearly full aux tank and the UAT never ever get's close to having an air bubble in it so fuel delivery is guaranteed. Because I went down in weight a little with my updated aux tank and I have everything disassembled to change the fuel lines and such (annual inspection during the hot dry months as I don't fly turbines at home this time of year) - I'm using that as an excuse to finally install my smoke tank. It's a center line pylon tank with the pump and the smoke tank inside the ''external tank fairing'' and completely removable when not desired - so as to keep the jet as a clean, light sport jet when I'm not smoking.
Thanks for the detailed description, I followed your A4 build on RC groups. Mine was put on hold as I was painting a couple of planes for some buddys. Its ready for painting in VF-126 Bandits agressor scheme with some first class decals from Ralle in Germany.
Im also trying to fit an AuX tank as I was a bit concerned with the fuel capacity. You combination of parallel and seried feed seems excellent..
I was initially going to power the scooter with a VT80 which I purchased, but then thought i'd use the P60 since it was designed for that..
regards
L
11-19-2012 | 07:54 AM
#11
RE: Tamjets A4 Tank issue
I did a ton of model research on line. I had to use a lot of artistic license to re-create what I wanted in terms of what, where and when... and "who" exactly my A-4 was trying to be!! Some of the nomenclature is seen on other paint jobs but "assumed to be" a standard place to put it when I could not find the exact pictures to show me on the paint scheme I was looking at representing [&:] My scheme is not what I consider true to life for any one particular jet. I don't want to crowd your thread with pictures of my A-4 but here are a couple pictures to show you where I put some stuff and it may help fill in the blanks on your own online picture search. Your A-4 will come out better than mine, I like your progress. I used to have literally hundreds of A-4 pics on my computer but I've purged a lot of my research photos in the last year to save space!!
Your A-4 looks to be coming out STUNNINGLY well. Along with Jamie Z's recently finished A-4, you guys will have the "sweetest A-4's on the net"!! Nice work Loukos, keep it up!!
Your A-4 looks to be coming out STUNNINGLY well. Along with Jamie Z's recently finished A-4, you guys will have the "sweetest A-4's on the net"!! Nice work Loukos, keep it up!!
11-19-2012 | 10:54 AM
#12
Thread Starter
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RE: Tamjets A4 Tank issue
You are too kind Eddie, I always thought your A4 was stunning, and it was the reason I went for the VF126 bandits as opposed to Lady Jessie which was my original plan...please feel free to post as many pictures as you like...the lovelly thing about forums is sharing each other's projects and learning
04-28-2013 | 04:32 AM
#16
RE: Tamjets A4 Tank issue
NICE WORK!! Excellent flying location for the first few flights. She looks great, right out of Top Gun the movie.
How much flap deflection do you have? Where is your CG set with empty tanks and a full UAT? What was your final weight?
How much flap deflection do you have? Where is your CG set with empty tanks and a full UAT? What was your final weight?
04-28-2013 | 07:32 AM
#18
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My Feedback: (2)
RE: Tamjets A4 Tank issue
Thanks Eddie,
Nothing like the sight of an A4 on a low pass banking its wings...
The site is a dry lake known as Ladies Mile on the Raf akrotiri base in Cyprus, the perfect place for all jet maidens..
Flap setting as per the manual with recommended crow mixing, spot on.
Nothing like the sight of an A4 on a low pass banking its wings...
The site is a dry lake known as Ladies Mile on the Raf akrotiri base in Cyprus, the perfect place for all jet maidens..
Flap setting as per the manual with recommended crow mixing, spot on.
