Tanque

Mark looking at the photos more closely I'm betting the engine in your second Tiger is a HB .61. It is likely a "Stamo"
version with integral rear fan; originally made for helicopters. It appears to be using a Perry type carburetor, many guys loved those carbs
I never had good luck with them- they are made with a strong plastic body and I believe but not certain that they may have been an option
for HB motors( may have been OEM). The engine is a glow engine and the assembly that looks like a spark plug wire is likely a part of a self starter / glow driver to heat up the glow plug when needed. Many folks use a glow driver to help keep a glow plug glowing at idle speeds especially when the engine is set rich.

That HB was a great engine in its day. Still is.

I'd be curious to know what you find out to compare my perceptions with the actual setup.

Jerry

Gun Tech

Jerry,
I appreciate the lead, I will do some digging to see if I can gather more data.

Mark

Tanque

I remembered seeing this past item on ebay.de. Only it didn't have a heatsink heat installed. Sort of over kill with the integral fan.

http://www.ebay.de/itm/HB-61-Helmut-...p2047675.l2557

I'm more convinced than ever this the type of engine you will find in your second Tiger. Rather a rare bird that.

Jerry

Gun Tech

Jerry,
I found a site that broke down the evolution of that motor and the large cylinder head was used for 2 years around 1977. Seems to be a well regarded motor in the helo world, so I will keep my fingers crossed as a tank power plant (assuming I can sort out getting it to run).

Mark

Tanque

I would definitely pull the engine and starter out and disassemble them, especially the engine. If the gaskets break and almost certainly they will you can cut new ones from heavy
photo grade paper if you can't find them from Mecoa. I say to disassemble the engine because if there's gunk or worse in the bearings, cylinder or piston ring you'll be glad you did.
I don't recall if this particular engine had a Dykes type ring or a regular ring but I've found that older engines almost always get an accumulation of crud in the ring groove and or the
ring is stuck in place with fuel residue. This is always worse if the previous owner was a 'run it and forget it' kind of dude. If you decide to pull the ring exercise care as they break easily.
I can get cocky when working on mine and don't think twice about pulling the ring, fortunately so far I've never broken one.They are usually made of cast iron/ meehanite which doesn't
take excessive bending well. But a stuck ring isn't good either. If you can get the cylinder liner out I would do it, I made a tool specific to my Webra 40 engines to do this. not knowing the
amount of action yours has seen or the type of fuel used it's difficult to know what to expect but a clean cylinder is a happy cylinder. I believe there are still arguments as how to clean a cylinder.
I will resort to the finest steel wool when I have to but I will start with some metal polish- in other worlds the absolute finest abrasive I have on hand. Final cleaning for everything is clean methanol.
If you find scoring on the ball bearing balls or races you have to decide if it's worth it to replace them or try to use them; I've done both knowing that if a bearing breaks it's usually fatal to the engine.


Even if you believe the engine would start I wouldn't do it before cleaning. The only way I wouldn't do I what I'm recommending is if the engine is brand new. (Even then, and I don't know that HB had this problem
but with a new engine ( especially current imports) I'd pull the head and rear cap to ensure no machining residue is in there ) I've learned the hard way.

What I do first with a new- used engine is just dismount it remove every thing I can especially the glow plug and soak it for a day or two in methanol. I'd would definitely remove the carb and that plastic
fan shroud beforehand.

Should be fun, I enjoy doing stuff like that.

Jerry

Gun Tech

No news on the other tank from Germany, but I did finally get around to using the tachometer to get motor RPM for this one. I unbolted the motor and kept it wired, so the values are real world going through the ESC. That big monster only turns around 2100-2200RPM's!! It doesn't twist with much authority when power is applied, but it is nearly silent. Seeing that it has a sprocket on the end of it, I don't plan to grab the output to feel the resistance. Tomorrow, with the help of a friend, we will do some time/distance tests to see what the scale speed is. I suspect that it is less than the scale value of 4KPH, so this may be a reason to look at options to upgrade to a more modern electric. That's all for now.

Mark

Max-U52

I do believe that in your scale top speed should be 2.8 mph. Doesn't seem very fast, does it?

Gun Tech

Max,
Scale speed should be 3.8KPH at full tilt for on-road speed and 2.0KPH for overland travel, that being based on published info from the Internet (and it's never wrong). I didn't break that down to MPH, since metric is easy to work with. The results of today's time trials are in: right now I am at an actual speed on a flat sidewalk of 1.29KPH. It took just over 28 seconds to cover 39'. That was measured several times to verify consistency. In addition, with the help of a minion, I was able to re-test the output RPM of the motor and I am seeing a stable 2370RPM (measured input voltage from ESC was 11.6V). Sooooo, that means I need a motor with an output RPM of approximately 7500RPM to put me on track with a real world speed of 4KPH. After a visit with one of the LHS's, I have a 775 motor that has an output RPM direct wired to a 12V battery at 10,000 and direct wired to a 7.4Vbattery at 7400. Methinks we have a possible solution with this combo! Torque will be the wild card, since I have no idea what that old motor is actually capable of, but the 775 took a bit to stall and once I let go, it took off with my rag attached (friction fused it to the plastic belt drive). I am not feeling too frisky about trying that with a metal sprocket just yet. I may set up a test platform with the other Tiger, while I am cleaning up the Nitro motor to see if it works. If the 775 works well at 7.4V (7500 RPM target), I can cram 6 batteries in half the space of the 12V SLA units and be using batteries that I can use in most all of my tanks! Think about that one, six 5100mAh batteries for 30.6Ah of on tap running time! Heck, I could jump start your car with the tank. By the way, the 4KPH value I stated previously is what Seki listed on the manual and was one of the few things not in Kanji. I guess I am at a standstill for now, since I don't feel like making any alterations on this tank just yet. I will let the next one be the guinea pig while I sort out the gas engine, so all I can do is wait.

Mark

Max-U52

Interesting we should touch on the internet never being wrong. My internet says top speed on the autobahn (I'd say your sidewalk is close to scale autobahn smoothness) is 45.4 kph (28.2 mph for us hillbillies). One great thing about your scale, just move that decimal one to the left! I'd say you need still more speed! Or as Tim Allen used to say, MORE POWER! AR AR AR!

Max-U52

That's twice it double posted on me today. The first one might have been my fault, but I know I did this one right and it still got me. DOH!

Gun Tech

Max,
Simmer down, I don't want to be flinging parts to the points of the compass. I want to keep the ability to crawl, but it would be nice if I can scoot along at a pace that won't leave me fossilized. The only feature I have to keep is the rotation of the motor to shift the mechanism with the gears and clutch bearings, unless I decide to lock it out permanently. That is a modification I will hold off on until I can be sure that I won't compromise overall operation.

Mark

Tanque

One great thing? One??? One of MANY great things, bub!

Jerry

Max-U52

Jerry,

I don't know, I've been thinking about doing at least one in 1/6 scale. Is 1/10 better? Why?

Mark,

No simmerin' down! More power! Seriously, though, I'm just starting to explore 1/16th scale motors (torque, rpm, performance, etc, etc) so that's lookin' easy compared to what you're takin' on. More power to ya, Bro.

Tanque

I was just teasing regarding scale, sort of. There is no perfect scale. I will say this. 1/10 scale was far more popular when Mark's tank was originally made.
1/6 was unknown compared to 1/8th. Before the advent of 'store bought' tanks many modern vehicles were made up around common
bicycle roller chain used as the basis for tracks and those scales were more 1/8 or 1/7. What store bought tanks that were available were mostly
1/10 scale. At one point there were at least 4 or 5 makers of 1/10 in Germany and 2 or 3 in Japan. There were probably others but before the
advent of the 'net news traveled slow. Besides cost I never really understood why 1/10 scale never caught on over here; somewhere along the way
I stopped trying to figure it out. Perhaps if there had been a series of after market items to stage with them it may have been different.

I just like 1/10, to me it has the right balance of size and performance and I can still move them around relatively easily, My heaviest to date
is my King Tiger at around 92 pounds fully loaded

During the heyday of Seiki, Tamiya's Sherman was the only 1/16 tank really available; Bandai's 1/15 scale line ruled the roost and there were only rumors about
other companies making 1/16. I had been told by a distributor that Bandai also had intended to add a T-34 and Sherman to their 1/15 lineup but cancelled these plans and froze their
line in the mid 1970s- never had any way to substantiate that. Their Tiger I was their last and best offering.

Sorry I have no intention of hijacking this thread. I'm looking forward vicariously to Mark's second Tiger!

Jerry

Max-U52

I wouldn't call that hijackin' the thread. It is an investigation about a 1/10 Tiger so I imagine a little discussion about the scale would be in line. I found what you said very informative and almost all of it was new info for me. I sure hope 1/16 scale doesn't meet with the same fate. I would think 1/6 would have been more popular because of GI Joe. Lots and lots of accessories there, especially back then.

Gun Tech

Jerry,
Great input to help the 1/10th cause! Don't lose any sleep over hijacking, this all pertains to the subject.

Max,
Other than cutting back on the testosterone boosters a bit. I agree that power is a good thing. I just want to tread carefully and avoid tearing up the gears/sprockets/tracks which are not "off the shelf" items. I might be able to make quite a few parts, but not if I can avoid it.

Last night I did some more checks and found that the ratio from the clutches forward to the sprockets is 18:1. From another thread, I had seen that someone said the sprocket RPM of a Tiger would be around 130RPM, but that did not state the equivalent road speed. Assuming that was full tilt road speed, you are looking at an input to the gear train of 2340RPM. That means as a possibility, the clutches could be eliminated and two motors operating at 10,000RPM or 7,500RPM going through 4:1 or 3:1 planetary gears respectively, could simplify the drive train further. This is just the evil squirrels at work in my noggin. I am a solid fan of simplifying designs to increase durability, so this is typical. I spent more time tinkering with that bizarre unit with the clutch bearings and it continues to make less sense the more I look at it. It's almost as if someone added it as a joke to torment me. That's all for now.

Mark

Tanque

The only thing I will say about adding more power to a model tank, any model tank is tread carefully. The initial gearing takes a beating especially in an electric powered model.
The ramp up of power applied is short and the gears are subjected to quite shock and load. I've seen the effects, gear teeth getting so badly deformed over time, losing their profile that they begin to terrible noise then fail altogether. On larger models such as the Seiki this effect is going to be worse.

jerry

Gun Tech

Jerry,
I am totally onboard with that. If I ever figure out how to enable the feature on my Clark board, there is a way to configure the throttle inputs to provide a more realistic acceleration and deceleration. With that ability to ramp up no matter how hard you apply throttle, that would significantly reduce the shock loading. Of course this will only apply if I progress far enough that I have actually made the switch to a twin motor set-up and can utilize the commercially available boards. No matter what, I have no desire to have a tank that destroys itself. Besides, my coordination with my thumbs is not good enough if I make it too fast, I would wind up in one of those FAIL videos.

Mark

Gun Tech

Well, a big friggin box showed up today from Germany! However... I think I will have to name a thread for this one, "The start of an autopsy". What a cluster f**k! Let me clarify, I am delighted to have this tank, but it has been so terrifyingly altered to make the Nitro engine work, I see this as a ground up rebuild and that most likely won't include the Nitro engine (Jerry, want to buy an engine, LOL). The previous owner made some really weird alterations and he definitely loved batteries. I count six different batteries secreted around the tank and servos for functions as yet undetermined. Right now, a major teardown is warranted and an inventory of parts to re-use. While I am at it, I will be using a lot of paint stripper. The key point that will make me toss the Nitro engine is the fact that this tank only has the ability to go forward, there is no provision for reverse. Right now I have fantasies of electric motors and a Sturmtiger upper. The good news is that the chassis and tracks look to be in excellent condition, although the suspension is sluggish due to coagulated grease and is in need of a thorough cleaning and lube. I have a bunch of photos uploaded, so I will probably start a separate thread later.

Mark

Tanque

Yea, Mark I hear you brother. I've seen remarkable violence visited upon these models over the years. What fries my toast the most is
the sort of guy who if they don't know how something works or what it does 'works around ' it until the behavior fits their view.

Sure if you decide to unload that engine I'll buy it and run with it. I love working on those things. I don't do much on (1:1 ) cars anymore, got tired of the mess
and figuring out how to lift/ move things. I like an engine I can carry in one hand.

Let us know what you do with the new child. Photos!

Oh yeah.... Happy New Year!

Jerry

Gun Tech

It's a tomb here at work, but luckily I decided to bring the chassis along. Hull interior is stripped, tracks are off, everything but some lights have been removed and gearbox has been partially broken down. My co-workers already expect my odd behavior, but even they were quite intrigued with the tank and the general consensus is that Rube Goldberg doesn't hold a candle to the guy that put this together. I will upload the photos from last night, later today when I get home. The clutches had significant evidence of heat bluing from being overheated, so I think the Nitro engine was way too much for the driveline. I think I will proceed with the idea to retrofit the gearbox with a pair of motors running through some planetary reduction units. Time to hunt down a set and a few other bits. I still have my work cut out to get this horrible paint removed from everything, so I will warn my wife I will be in the garage with a stripper.

Mark

Gun Tech

It's a tomb here at work, but luckily I decided to bring the chassis along. Hull interior is stripped, tracks are off, everything but some lights have been removed and gearbox has been partially broken down. My co-workers already expect my odd behavior, but even they were quite intrigued with the tank and the general consensus is that Rube Goldberg doesn't hold a candle to the guy that put this together. I will upload the photos from last night, later today when I get home. The clutches had significant evidence of heat bluing from being overheated, so I think the Nitro engine was way too much for the driveline. I think I will proceed with the idea to retrofit the gearbox with a pair of motors running through some planetary reduction units. Time to hunt down a set and a few other bits. I still have my work cut out to get this horrible paint removed from everything, so I will warn my wife I will be in the garage with a stripper.

Mark

Tanque

I hope it wasn't painted on the inside if they ran a glow engine. An interior painted glow powered metal model ( tank ) never ends well.
Gooey, messy gunk is the result.

A chlorinated paint stripper is your key to salvation; as noxious as they are they'll make short work of paint even if the previous owner used some sort of glow fuel resistant
paint.

Jerry

Gun Tech

Jerry,
Do you mean like painting the tops of the plastic fuel tanks? Luckily, the hull was mostly unscathed by their paint job.

Mark

Tanque

Nah, that's minor. One of my Maier Panthers purchased used had a thick coat of some ghastly sand colored German fuel resistant paint that took a while to remove even though it
had started to break down in places that were in contact with fuel or exhaust goo. It was gross in the extreme.

From what you describe ya got off easy.

Jerry