1/8th scale Tiger
 

Just been looking at this Tiger, 50cc petrol engine, all metal tank cool and probably a cool price. lol :D
[link]http://www.modelworks-int.com/asp/d-no.asp?ProductID=18&Process=1&CatID=3[/link]

RE: 1/8th scale Tiger
 

I remember that, very cool!

I'm going to scratch build someday a 1/6 M18 Hellcat and power it with a 9 cylinder radial engine, just like the real thing!

RE: 1/8th scale Tiger
 

James, where are you going to get a 9 cyl radial to fit in a 1;6 scale? [X(]

RE: 1/8th scale Tiger
 

Scratch build [X(][X(][X(][X(][X(]:D:D:D

RE: 1/8th scale Tiger
 

Hi Bill,

Technopower, Rotec and Cox are some that come to mind. I think Technopower had the ideal engine last time I looked into it. I'd hook the motor up to that gearbox that the guy who built the Stuart that jumps bicycle ramps with the Honda 4-stroke.

RE: 1/8th scale Tiger
 

That sounds like a nice deal for my Stuart. With the new correct single block tracks from Jack Yang I have on it, a better engine would be nice and also get away from the single speed hangup. :eek:

fv432...that's a lot of scratchin'. [:@]

RE: 1/8th scale Tiger
 

I've seen some of those engines perform in a tank! Talk about REAL speed! :D

RE: 1/8th scale Tiger
 

Really? Where? Would love to see it, would save a lot of R&D time!

RE: 1/8th scale Tiger
 

There have been a number of companies who've made or make radial engines. The afore mentioned Technopower
makes 5, 7 and 9 cylinder engines and has quite a history. Saito makes a 3 cylinder, OS makes a 5 cylinder and Seidel in Germany probably made the prettiest. There are others but these come to mind. I've owned radials from most of these guys at one time or another.

The greatest challenge will be keeping the engine cool enough yet hot enough to run well. It you run glow you will need an elaborate glow driver, if you run ignition and glow fuel be prepared for much higher temperatures. Gasoline and ignition is out of the question if the engine is aircooled. You'll only be able to do it if watercooled. you don't have the luxury of the airflow
you need. I have experience with four cycle engines in tanks and boats, at present I habe a 1/10 Sankyo type 74 powered by a O.S. 48 Surpass. I run it on glow ignition but still after 40-45 min of running it needs a rest, I use a belt drivn fan. I originally ran it on gas ( tiny NGK ME -8 plugs) and it started and ran wonderfully; I use a throttle couple timing advance to minimize backfiring and ease of starting. But I'd only get 10 min of run time on a cool day before the engine got so hot the fuel boiled out of the carb and the engine stopped. As it is I use a stainless steel header and exhaust system which has a limited life span.
4 cycles run hot(er) than two cycles. For those engines that use chromed aluminum cylinders( Saito) overheating isn't an option. This a greater part of the reason I didn't carry out my plan to power my King Tiger with a Saito 90TS. I also had plans
to build a 1/8 Tiger I and power it with an O.S. Flat four( Pegasus) 320. I had the engine, ignition system, starter and gearbox
but decided the logistics weren't worth it. Cooling is the name of the game. Even when I ran large gas boats( Kawasaki, Tanaka(Tas) and Kioritz engines) during the 80s (as well as tanks) I learned cooling the engines that were buried in a closed hull required good airflow AND water cooling.

I also have two 1/8 Sankyo type 61( at 113 pounds each- you see one in my avatar) that are powered be aircooled Zenoah 23ccm gasoline engines. They get monstrously hot. the method Sankyo employed to reduce heat buildup was to minimize the restriction ( read no muffler)
in the exhaust system and make it VERY short. Makes for a largely unpleasant model to run for long periods....

The idea sounds great and no doubt could be made to work but even I won't spend the time to do it until viable water cooled
multi cylinder engines are available. I have no interest to build an engine like that either; not for a tank anyway...

Jerry

RE: 1/8th scale Tiger
 

Well what form of cooling did the Stuarts use? Didn't one of the Shermans also use the aircraft radial engine as well? I'm sure some kind of fan unit could be used that circulated air around the cylanders of the radial engine to keep it cool

RE: 1/8th scale Tiger
 

Thanks for the input Jerry. It's only a dream at this point. Like the real Hellcat, this one would have a large engine driven fan and the top deck was open to draw air in and push it out the back. Lots to do before that day comes.

RE: 1/8th scale Tiger
 

Clearly the tanks that used aircooled engines solved the problem; I'm not sure what the full size systems used besides some giant sirrocco fan and efficient ducting. Porsches and VW's solved the problem handily. I was plannig to emulate the clever ducting that Porsche used on the VW and 911 series. I think in my case while the Saito 90TS fit, it was uncomfortably snug not allowing sufficient space for proper ducting. I had planned to use sirrocco fans I had made up specially but when it all came together as a "power pack" it was just too limiting because of its size; due to constraints in the interior of my King Tiger there were only two positions I could install the engine. So I opted for a proven design layout I have and I'm glad I did. The 4 cycles need strict maintenance( valve lash adjustment for one) and after run care, very difficult in a tight compartment. The two strokes don't sound anywhere half as good as a 4 but they are self cooling ( in part), simple, robust and very powerful. High cost of fuel and sound(however this can be mitigated with clever exhaust design) are the main complaints but after a while you grow accustomed. My oldest engine in basically continual service is 32 years old although it is time for an overhaul now...

You gents who have a mind to use a radial can take it on as a challenge. It should prove to be quite the model engineering showcase.

Jerry

RE: 1/8th scale Tiger
 

the Model-works Tiger I was not very well detailed and had running problems with the engine, never seen one run but have heard that a few have been converted to electric power these things are very expensive for there scale you would be better off with a 1/8 Tiger from Mark I tanks

RE: 1/8th scale Tiger
 

I would emulate how the real Hellcat was installed in the tank. It was mounted on rails and by disconnecting the drive shaft and some ancilliary items you could slide it out the back in record time compared to the Sherman. This would allow me to access the lower cylinder heads without dismantling the tank. The fan was mounted on the crankshaft if memory serves and was the same size of the engine.

RE: 1/8th scale Tiger
 

The tank looks cool but the price[:'(]

RE: 1/8th scale Tiger
 

cost was enough deterrant,[:@] but then using such a hot engine in a plastic hull just wouldn't work. [&o]

Pzwest, all early Shermans had the 9 cyl radial engines. The A4 had the Chrysler muti bank pack with 5 truck engines in a star pattern (can you immagine keeping 30 cylinders in sync[:'(]) and A2s had diesel. M-4A3E8 used the Ford GAA 490 HP V8, but the M-4A1E8 still had the radial. The radial engines had a huge fan mounted on the clutch housing on the flywheel which dragged air in the front grilles directly behind the turret. The engine had a shroud around the entire engine with baffles aiming the air flow to the piston fins and other hot spots, so they ran fairly well when they were not "hot dogged" even though they were a bit underpowered. Radials had a bad feature in cold weather in that the crew had to hand crank the engine (supposed to have been 50 cycles) to distrubute the oil from the lower 3 cylinders and to prevent hydrostatic lock. In many cases, they cranked it up, let the huge white cloud clear, add 5 gallons of oil and moved out....if the engine didn't lock up. Didn't help in hiding your position. [&:]