Type VII U-Boat by ir3 - Engel - RADIO - model sold

[ir3]

The Engel Type VII build has been going on for some while with the main thread on RCG: www.rcgroups.com/forums/showthread.php?t=1819581. My intent on that thread was to show only the differences in my build compared to most of the existing build threads.

 

Two upgrades that were not covered in older threads are changes to brushless motors for the twin shaft drive and the battery pack from D Cells to Super C Cells which have twice the power in a package that is about half the size. It took many months to get the upgrades from Engle and the battery pack required another set of upgrades. In time I will summarize what I have done up to now but first a comparison to get an idea of the size. The Tail Cone is off the sub but is shown in the approximate position to get an idea of the total length.

 

Until next update,

 

IR3

 

 

[ir3]

All of the electronics are mounted in what Engel calls the Tech Rack. The Tech Rack slides into a Lexan tube and with O-ring seals on each end of the Tech Rack, the Lexan tube becomes the Water Tight Compartment (WTC). In the original electrical layout, there were no provisions for switching power on/off. This meant removing the Tech Rack from the WTC to disconnect battery connections. The first change that went into the Tech Rack was a magnetic switch that allowed main power to be turned on/off which was great for interday sailing/submarining. The pictures show the installation of the Magnetic Switch and the battery pack with the old D cells. Note that this upgrade was made before changing to the C Cells and Brushless motors.

 

Until next update,

 

IR3

 

AND OH YES, THE ORIGINAL BATTERY PACK CONSISTED OF TWO 5 CELL PACKS CONNECTED IN PARALLEL. A DEFINITE NO-NO. IF THERE IS A SLIGHTLY WEAK CELL IN ONE 5 CELL GROUP IT PULLS DOWN THE OTHER 5 CELL PACK. THE TWO RED CONNECTORS ALLOW ME TO PUT JUMPERS TO PROVIDE POWER TO THE MAGNETIC SWITCH AT THE POND AND ALLOW THE INDIVIDUAL 5 CELL PACKS TO BE CHARGED INDEPENDENTLY. WHAT WERE THEY THINKING AT ENGEL?

Edited January 10, 2014 by ir3

[ir3]

So now everything has been packed into the Tech Rack without a bit of space to spare. Then along comes the Brushless Motors and the Super C battery pack. The nice thing about the new C cell pack is a 4.8V tap is provided. This gets rid of the BEC and a bit more room. Next comes the Brushless Motors and the ESC's. The motors are shorter than the brushed and the ESC's are smaller. All of a sudden space is opening up at the aft bulkhead where the motor shafts exit the WTC. I was now able to move the charge/run sockets to the area near the Brushless Motors and the wiring was greatly simplified.

 

 

The new battery pack is lighter so some fiddling with the ballast will be necessary.

 

 

The magnetic switch was moved to a better spot where it can be sensed through the hull with a fairly strong magnet.

 

 

The Tech Rack at this point in time is now looking very functional and not so packed.

 

Until next time,

 

IR3

[ir3]

So after getting C cells in, the Brushless Motors and ESC's in and everything starting to look good, uh uh. The brains of the dive system is the TMax VII. This mounts on a platform above the motor/esc compartmant. Well it was a tad too tall and two of the long threaded rods which help keep the long Tech Rack stable interferred with the mounting of this unit. Another modification the the shelf to safely hold the TMax in place needed to be accomplished. This required cutting out an area the size of the TMax and recessing it about 1/4", the thickness of the mounting plate.

 

This picture shows the interference.

 

The next few pictures show how the problem was corrected.

 

 

 

And finally the TMax unit comfortably in place. Note that the BEC is no longer mounted.

 

 

So now things are looking a lot better for the Tech Rack but there is more to come.

 

Until next time,

 

IR3

Edited January 11, 2014 by ir3

[ir3]

So now things are really looking up. Most of the electronics have been updated, there is room to make maintainence a bit more easy but yet another problem shows up. The Engel electronics package is very sophisticated. During the initial installation of the components I learned a bit about how they work but since I am still in the construction phase, there is a lot more to learn. Very sensitive pressure sensors are in the electronics package as well as level sensing or inclinometer sensing. You can set the boat to run smoothly at Periscope depth. Once partially or completely submerged it is very difficult to keep the boat level from the operators standpoint. The electronics package is tied into the bow and stern planes to constantly make corrections to keep the boat level. This is over ridden when the operator decided to continue the dive or come back up. It goes on and on. Many fail safes built in. I will elaborate as I go through all of the testing and calibration.

 

There is a shelf for one of the pressure sensors. The location of this shelf was probably for an earlier version of the sensor. The TAES is programmable from the transmitter and when activated remembers the static pressure at a particular depth. When the sub has no forward motion at depth, this little gadget continuously adjusts the forward and aft ballast tanks to maintain level. The original location for mounting the part did not allow a smooth bend in the tubing coming from the pressure sensing port. This shelf was moved to allow a smoother run of the tubing.

 

It is a bit difficult to see but the tubing will be kinked when the Tech Rack is slid into the WTC.

 

This picture, although not very clear shows the TAES remounted with the tubing now inboard and a smooth run to the sensor port..

 

 

There is one more problem area that will be covered in the next post.

 

Until next time,

 

IR3

[ir3]

With the mechanical problems in the Tech Rack solved it was time to install the it in the WTC. The next problem and hopefully the last showed up. The bow end of the tech rack has a bulkhead with an O-Ring. This is the forward seal for the WTC. There is a cone in bow that accepts this bulkhead. The bulkhead has 3 adjustable retaining pins and they slide into the cone and with a twist to lock the WTC in place. Well as the first picture shows, there was a bit of a mis-alignment.

 

 

With a lengthening of the slots in the cone, a correct alignment was achieved. This was not without great difficulties, however. The nose cone is bolted to a bulkhead which is fitted at a specific spot in bow section of the hull. There are two bolts that hold the cone in place. One bolt is easy to get to but the other is tucked down almost against the hull and is a nightmare to get on and off. I tried flexible extensions, magnetic nut holders, modified sockets but could not get this nut on and get it tightened. After consulting others that have built this sub they agreed that one nut on the top should be OK. The object is to keep the nose cone from twisting when the Tech Rack is twisted in.

 

 

After lengthening the slots, difficult to see, the Tech Rack is aligned.

 

 

 

So mechanically speaking, most of the problems have been solved.

 

Please keep in mind that this kit was not a disaster in the making from Engel. I purchased this sub years ago when we had a very favorable Euro exchange rate. My best guess is that the Tech Rack minus the electronics was a very early design. When the kit was shipped, updated electronics were included. It is most likely that the new electronics were not fitted to the early Tech Rack mounting components but mods were made to later kits to correct the problems. Also, I installed two upgrades and had to make the various changes to accommodate the upgrades.

 

It was an interesting experience getting the kit to it's current state. From here on, the updates to the thread will be current.

 

Thanks and until next time,

 

IR3

[ir3]

The instructions show the aft section permanently fastened to the rear bulkhead of the Tech Rack. I did not like this since it would make it extremely difficult to do maintenance work on the propeller shafts and the push rods to the aft dive planes and rudder. To solve this problem I decided to bolt the art section to the rear bulkhead using 5 screws.

 

The first picture shows the blind nuts attached to the rear bulkhead.

 

 

The next picture shows the 5 tabs in the aft section. Note also the guides for the rudder and aft planes push rods. Not too elegant but functional.

 

 

This basically brings the thread up to date on my progress.

 

Untill next time,

 

IR3

 

 

 

 

[ir3]

With the mounting tabs in place for the nose cone it was time to get some primer on and after priming, get the rudders and aft planes in place.

 

 

It looks a lot better in primer. Next Rudders and Aft Dive Planes in place.

 

 

The space to work in on this sub is quite minimal. The Type VII/C's were quite narrow at the stern. Getting to the grub screws with my meat hooks is very difficult. There is still a bit of tweaking to be done to get the rudders and planes zeroed but that will happen when the RX is put back in.

 

 

It may look like a lot of space but it is deceiving. The Tech Rack and WTC have been removed for painting otherwise the tail cone would have been mounted with the prop shafts.

 

It appears that the twist in the hull of the Confederacy might have been fixed. If so, it will be back on that project for a while.

 

IR3

 

 

 

 

[ir3]

The hull is painted so now I can get back to finalizing the WTC. It is very difficult to get a full view and if I use close ups all of my dismal painting will be exposed.

 

 

Still waiting for a new LTR6. It's functionality is improved and includes extra servo plugs. Anything that reduces the wiring clutter is welcomed and it eliminates a Y harness that connects the fore and aft planes. It also has a slightly smaller form factor which is alway welcome in this highly cluttered WTC.

Until next time,

IR3

[ir3]

With the computer down for a week and waiting for the delivery of a part from Engel it was slack time for me. The replacement for the Pitch controller LTR5, the LTR6 finally arrived. The installation is very clean and now it is off to recharging the batteries and starting the setup of the electronics package.

 

The new LTR6 just arrived on Saturday and it is time to install it. It is a very nice design in that it eliminates Y harness to control the aft and forward planes. Not only does it eliminate the Y harness but supplies both +/- servo outputs if the servos are not moving in the right direction relative to the pitch stick on the TX.

The first picture shows the LTR5 clutter and the second shows the clean LTR6 installation.

 

 

I will now get started on recalibrating the electronics.

Until next time,

IR3

[NAZGÛL]

Very nice work, it's impressive that you get get all the things installed so neatly. I like the design of this sub also

 

 

/Matti

[ir3]

With the hull painted it is time to get back on the mechanics. The rudders and dive planes are in as well as the prop shafts and props. Lots to do on the props. There is one right hand and one left hand. I need to determine which side of the boat the props should go and then I will need to reprogram the Brush-less ESC's to get the shafts rotating in the right direction.

With the limited space to work on the rudder and planes installation and my meat hooks for hands it is quite a struggle. After getting everything set up, two problems showed up. For the planes, the servo for the aft planes does not center properly. I swapped the rudder and planes at the RX and the problem persisted with the aft dive plane servo. This will have to be replaced. It is a Robbe 110 BB MG but I think the Futaba S3001 is the correct replacement. I might look for the Robbe locally.

Another issue is a bit of back lash in the rudder system. I do not get a good return to center with the rudders. One of the rudder posts seems to be a slight bit oversize causing the rudder to be a bit on the loose side. I am not too worried about this as I can fiddle with the stick on the TX a bit to get them centered. Replacing the rudder tube is not an option at the moment.

So, the servo will be replaced and then it is off to setting up the props and the dive system.

Until next time,

IR3

[ir3]

Well, after giving the rudder problem a lot of thought the problem has been found. The geometry was wrong on the horn. It should have been on the other rudder post. This not only makes the line of the push rod correct but also has the rudders following rudder stick on the TX. It was quite involved since I needed to redo the cross coupling between the rudders. A very lengthy process.

The problem with controlling the dive planes is that the LTR6 needs to be calibrated. It does not know what level is as of yet so it has no reference to level the dive planes. The servo is just fine, just an LTR6 calibration.

Until next time,

IR3

[ir3]

The problem with the dive planes servo is solved.      The LTR6 is a very clever device. It is internally set for a depth of .4 meters or about 1.3 feet. It has a very sensitive pitch sensor and a depth sensor. The pitch sensor, when at periscope depth, helps keep the boat on an even keel. The LTR6 has a connection for a 3 position switch which allows 3 modes, off, relative depth, and absolute depth. With no switch connected, the device is in absolute depth mode. Since the Tech Rack is on the bench it is not at a depth of .4 meters. Therefore the device is commanding the planes to achieve the absolute depth and thus very little control from the TX. With the switch connected and in the off position, complete control of the dive planes comes from the elevator stick of the TX.

These Engel devices are very well thought out and it takes a bit of time to fully understand how they operate.

Until next time,

IR3

Edited February 14, 2014 by ir3

[ir3]

After doing all of the work to create a removable tail cone, at 3AM I awoke with an epiphany. Why not just add a few flood holes in the tail cone to get access to the grub nuts on the prop shaft couplers. A little touch up paint and one will never know.

That being done I can now get started on setting up the props and make sure they are turning in the right direction.

Until next time,

IR3

[ir3]

There is not much to report with visual looks but the prop shafts are now aligned and spinning in opposite directions. Now I just have to make sure I have the props on the correct shafts. :unsure: Getting the shafts aligned is quit a process. If the stern cone was exact, the strut supporting the dive planes bearing, and the prop hub is accurately brazed then everything might just line up properly with no friction to speak of. Not so fast. It took about 6 hours of fine bending on the prop hub, filing the fairings where the prop shafts exit the hull, and making adjustments to the center strut (I believe it might be called a skeg) and aligning the prop hubs themselver (adjustments in 3 dimensions), makes it quite a task. But the work on the aft section of the sub is complete. Now it is into the WTC and I can set up the forward planes. I have some mechanical advantage issues to work out. I used the notches recommended in the plans for the dive plane bellcrank but I am not getting much deflection with full 90 degree servo motion. Hopefully this will be a simple change of where I connect the dive planes pushrod on the bellcrank. Lots of work!!! I think this is the toughest of the Engel boats to set up. I guess I am just a glutton for punishment.

 

Until next time,

 

IR3

[ir3]

I did a little bit more work on the stern plane geometry and I am now getting about as much stern plane movement that you have achieved. Looking closely at the Engel assembly manual, the linkage is well into the opening in the stern plane support.

 

NOTE THAT THE LINKAGE IS COMPLETELY CHANGED. IT HAS BEEN ADAPTED FROM ANOTHER TYPE VIIC BUILDER, JAN AKA HORSEMAN ON RCG, AND I THANKED HIM FOR AN EXCELLENT IMPLEMENTATION.

I shortened the control arm and placed the ball link in the center. In that way I will not get any interference from the sides of the stern plane support.

I am now getting about +- 18 degrees of deflection. This should be more than enough. I also plan on linking the bow plane into the LTR6 allowing for more help when changing depths.

I have a lot of hours in this and I will do no more on this linkage. As the famous Porky Pig always says "Deb-ebe-de-deb-de that's all folks!"

This has been a lot of work and a good deal of it very frustrating. I am actually sorry I tackled this boat instead of one of the Merriman 1/72 scale boats, which I juts might go back to. His boats operate very nicely in reasonably sized swimming pools. There is actually no clear water pool large enough for this sub in my area. The most I am going to be able to do is use the largest swimming pool that one of our friends has and do a little surface movement, drop to periscope and do a bit of under water movement. The turning radius is so big that I probably will not get a complete turn without backing one of the props. There is no pool in the area large enough to test the full functionality. I will be checking with some of the other U Boat drivers here where they run their boats.

IR3

 

 

 

Edited February 19, 2014 by ir3

[ir3]

The sub has been ignored long enough. I am now working through the next problem to solve. Having switched from the D-Cell battery pack to the Sub-C cell pack, the weight difference is dramatic. I do not have the exact specs of the actual battery weights since they vary based on capacity, a rough approximation makes the difference somewhere between 1200 and 1600 grams (42 - 57 oz). This represents a lot more lead ballast than was supplied. The plans and lead ballast layout, I am sure, is based on the older D-Cell pack. I have an email to Engel abuout how much extra lead ballast to put in and how to distribute it. He has the exact weights for the battery packs. I would like to avoid experimenting to get the boat to the water line since working within the hull is very cramped.

 

More to follow after I get some specifics.

 

IR3

 

OOPS, forgot the picture.

 

The first layer of lead strips is in but I need more infor before continuing. The space in the center will be used to add the extra ballast as needed.

Edited June 22, 2014 by ir3

[ir3]

The lead ballast showed up today so it's on with getting it into the hull. Unfortunately I did not get feedback on the weights of the battery packs so I had to do a little averaging. The 8000Mah D cells range from 135 to 145 grams. I used the average of 140 grams to get 2800 grams for the old 20 cell pack. The Sub-C cells range from 55 to 65 grams. I used an average of 60 grams to get 1440 grams for the the new 24 cell pack. The difference being 1360 grams or about 48 ounces. The final trimming of the boat, both to the water line and fore/aft will have to take place once the boat is finished and in the water.

 

The picture shows three bags of lead shot at 1 pound per bag. I need to add the rest of the bar lead per the print and then spread the shot evenly between. An addition of resin to keep the shot in place will probably add and ounce or so, well within the margin of error on the battery weights. Who knows.

 

 

Next update will show all of the ballast in place.

 

Until next time,

 

IR3

[ir3]

I mixed up some finishing resin and made a soup of 3lbs of shot and resin. It was poured into the center area between the lead strips and smoothed out. A check was made to ensure that there would be no interference with the WTC tube. The pics show the shot in place and the tiered assembly of the lead strips per the plans. One of the pics is slightly out of focus but the idea shows. The rings are the clamps for the WTC tube.

 

 

 

Next step is to get the foam cut and placed into the fuel tank blisters. Apparently there is a balance between the ballast and the foam and I have not found an explanation of this that I fully understand. I just hope that Engel is correct on the amount of foam and ballast.

Next update will be installation of the foam.

Until next time,

IR3

[ir3]

The flotation foam has been carved and test fit. The WTC tube does not interfere so I will be filling the pores with resin and install them. The instructions call for installing them with no air pockets or places where water might collect. Good luck. There is no way I can check for this. I can't even see the fit for the floats in the aft section of the hull blisters. All I can say is that the WTC tube clears them. The kit manufacturer should have made these pieces. They have the molds that created the hull, thus they have all that is needed to make the floats and have a good fit. Having said that, I will be installing them with Gorilla Glue. Gorilla glue expands while curing and by applying aggressively, most of the space and maybe all will be sealed.

Next update will be fitting the WTC and putting in the Tech Rack.

IR3

 

 

[ir3]

The floats have been sealed and installed. The floats at the aft end of the boat are the same size, just that the angle of the picture distorts the image. The WTC tube is in place but not permanently as of yet. The forward end that goes over the internal nose cone needs to be cleaned and silicon grease applier to help the O-ring seal. The picture with the slip rings does not show the O-ring in a groove around the outside. The WTC Tube slides over this cone and the O-ring supplies the seal. I included a picture of the internal nose cone installation to point out a problem. It will not affect the integrity of the nose cone itself.

The nose cone contains the forward dive plane servo and signals to that are passed by slip ring contactors on the tech rack (I can't seem to find that picture). The bottom bolt is impossible to put on as the end of the screw almost touches the fiberglass hull and I just can't get the nut on. The upper bolt, however, should suffice.

Now it is onto the completion of the Tech Rack wiring and preliminary checkout of all the functions.

Until next time,

IR3

 

 

 

 

 

 

 

[ir3]

Well after some long thought and research with other Engel Type VII/C builders, the suggested location of the RX is not a good one. It results in very long leads subject to noise and other problems. The question, however, was where to relocat the RX. There were two others but one was very near a brushed motor on one of the ballast tanks and the other was completely aft near the TMAX Ballast Tank controller. This is the spot I chose since the drive motors are Brush Less and will offer no source of interference for the RX. the following pics show the possible locations:

 

 

 

I chose the spot near the TMAX Control Module and it results in:

 

 

The RX is loose for the first photo.This reduces the length of the wiring of 3 channels by 1 meter each. The rest of the wiring will be greatly reduced as the leads for the ESC's are in close proximity.

 

If anyone finds this logic flawed, please let me know ASAP. Making new leads is very tedious.

 

More to follow.

 

Iran

[mtaylor]

Would using shield cabling work? If not shielded, wrap in aluminum foil and ground it.

[ir3]

Hi Mark,

 

Shielding was considered at one time. It was difficult enough to get the wires through all of the slots without the shielding. It was pointed out by several Type VII/C builders that in any case, putting the RX at the fore end of the Tech Rack was absolutely a poor idea. Because of the compactness of the Tech Rack there were very few options as I pointed out. The only reason I am putting the RX next to the rear bulkhead is that the RX sill not suffer any interference from the Brushless motors and the servo leads to the ESC's have noise suppression Ferite cores plus the cable lengths will be extremely short. The best of all worlds. So far I have removed nearly 18 feet of cables. The chances for glitches in the new setup will be quite minimal, I hope.

 

Iran

[ir3]

The rewiring is complete. It is extremely tedious since there is no extra room anywhere to tuck leads in that are too long. Each extension had to be cropped to the correct length. There is very little room since the leads have to pass between the WTC tube and the ballast tanks. Preparing the new connectors is no simple task either. Next step is to charge the batteries and start doing all of the static checks.
 

First Pic shows RX temporarily in place.

 

 

The next three shows how the wiring has been simplified and clutter reduced to a minimum. The antenna lead runs the length of the WTC in a piece of red tubing as seen in 4th picture.

 

 

 

 

Until next time,

IR3

[ir3]

Well, first the bad news , then the good news , then the bad news . With everything wired up and ready for testing I forgot to program the RX to the correct channel . Also, I wired the RX backwards so Ch-8 was plugged into Ch-1 , etc. By doing this  the programming socket for the RX was face down . The good news is that once I programmed it and rewired the servo leads, most of the functions started working correctly .

 

For the bad news, the aft ballast tank lead screw is binding either on the aft bulkhead of the battery pack or the forward bulkhead of the servo tray area. It is impossible to see what is happening with the servos in place and the battery pack hardware getting in the way . I need to pull the Tech Rack apart to try to find the problem. Of course, now it is greatly simplified since all the wiring now goes aft so it is just a bunch of screws and bolts,

 

Another problem is that the forward ballast tank lead screw is not moving at all . Hopefully this is just a bad connection in the servo lead. More on that after the main problem is solved.

 

Until next time,

 

IR3

[ir3]

After disassembling most of the Tech Rack the problem was found. The mechanism that operates the linear pot on the ballast tank was colliding with the TAES (static depth sensor that works with the ballast tank controllor) shelf preventing full movement to the limit of the pot.

 

Problem. The myopic senior did not mount the TAES properly.
The culprit: TAES mounting shelf collided with linear pot mechanism preventing full extension.
The Fix: Notch out the shelf and relocate slightly to accommodate the TAES without interfering with the WTC tube.

 

 

Result: linear pot in fully extended position with no interference.

 

Now I need to reassemble the Tech Rack.

Until next time,

IR3

[ir3]

The problem has been solved concerning the forward ballast tank problem. The spindle screw (attached to the ballast tank piston) extends but does not retract. The problem appears to be in the TMAX. I tried running the forward ballast tank using the connections for the aft tank. It works perfectly both extend and retract. Both of the ballast tanks fail to operate properly when connected to the forward connections. It appears that the TMAX is not reversing the voltage when switching to surface on the forward connections. I have been in constant contact with Engel but just informed them about the problem with the TMAX.

We shall see how this works out.

Until next time,

IR3

[ir3]

The TMAX is in the post back to Germany for evaluation/repair. It will probably be around 3 weeks before I get it back sot the sub is on the back burner for a while.

 

BTW, thanks for the likes. It is very helpful getting me through the trials and tribulations putting the sub together. It is very difficult to get add ons installed with the extremely limited space. The design is excellent for the space and size of the sub and the electronics are probably way beyond what is needed but Engel thought of everything. It will get finished and hopefully no more gotch yas.