Frog 150 Mk 3

Frog 150 Mk 3

Line up of some of Frog's other small engines family

 Frog 150 Mark III Is a superb high performance diesel ideal for 1/2 A Team Racing , smaller stunt model flying, sport, or contest free flight. Can be equipped with a spring starter for easier handling. 

 Data:

Displacement - 1.49 cc; Bore - 0.500 inches; Stroke - 0.460 inches; Weight - 3 ounces; Power - 0.15 b.h.p. at 15,000 r.p.m.

Watch as Jose' makes the little demon start up and run after a shaky beginning.  

https://drive.google.com/file/d/0Bw2P1xgqAWCuN3V3MVItWjNjLTg/edit?usp=sharing

Taifun Hobby MKII 1cc

Published on 9 Nov 2013 Today no rebuild stories as its actually always the same more or less,...except for the unusual rebuilds. I will show enough of them in the future, of course. In the case of the Taifun engines; most of them were made by Hans Hoernlein, they were always special to me since, they were very well made with very nice looks. Soon I will run a 2,5 Meteor and a 3,5 Super by Taifun. Both are early, non colored Taifun diesels. This engine is also a rebuild job for Jose, who is a kind modeller and engine collector from Spain. I am sure that he will love this rebuilt engine. The Hobby was never a real screamer, but was meant to be a excellent starter and a hassle free; rugged engine for the boys, who were new to this hobby....I guess that's why its called the "Hobby". There were 2 types of the MKII. The earlier model has the "teapot" intake ventury and the latter and final version has a round intake, as shown on this model. The 0.10 HP was not a real powerhouse but still more than the JENA 1 cc from one of our earlier featured engines, that I can compare it to..... only 0.08 HP. The scavenging is very similar to COX; 2 exhaust ports, and 2 transfer ports in "cross-flow" configuration. But it seems to be a very docile and dependable engine. Was still used many years after the diesel has vanished from the modeling scene; used as a " Hilfsmotor" or power assist for gliders. Fuel consumption was very modest and it was ideal for a auxiliary engine for a glider. But as you can see here; it starts and runs very well. The prop was a APC 8x4. Graupner recommended for the Hobby a 7x4 for C/L.. and for run in....for free flight a 8x4 is recommended. This engine still needs to be free up, as the piston is new....so the output should increase a bit even more in the next few runs. Shame I made no pictures when I started this project....it was really very bad....but as you see with some new parts it is almost like new again.

K&B 049 Stallion Rebuild Story

Data: Type: Reverse-Flow scavenged two cycle with shaft rotary valve induction. Weight: 2.25 oz including radial tank mount. 1.7 oz less tank, but with crankcase back plate fitted. Displacement:0.496 cuin.or 0.813 cc. Bore:0.400 in. Stroke: 0.395 in. Stroke to Bore Ratio 0.9875 : 1. Specific Output as tested: 1.55 bhp/cu in. Power to Weight Ratio: 0.548 or 0.725 less tank. Manufacturer: K&B Manufacturing Corp. 12152 Woodruff Avenue, Downey, Ca.

The rebuild engine has a pulled out connecting rod and we have the option of creating a conventional piston and rod set-up with a wrist pin arrangement, but we discover that the dimensions are almost exactly the same as the Cox 049 parts so we elected to modify a spare piston and connecting rod to fit the K&B.

The Cox piston's diameter is just a little bit larger than the stallion's 

The Stallion's piston diameter is measured below.

Below we see the measured diameter of the Cox piston.

I have decided to regrind the cylinder and the piston by about 15 one hundredths of a mm must be ground off in total.

Here we start to make a special lapping ring from aluminium alloy for shaping and finishing the piston.

Now the holes are drilled completely through.

The next step is to use a slit saw and split the ring along the the axis direction. 

Now we need a bored threaded hole for the tightening screw.

The hole is spot-faced to provide a flat surface for the tightening screw's head to sit on.

After the boring is done, a 2.5 mm thread is tapped by hand to exert pressure on the piston.

he lapping ring is now complete.

Drill out a wooden dowel and press fit it into the lapping ring for holding it during the grinding operation. 

The piston is resurfaced in several stages and polished to its final size.

The honing arbor for the cylinder is made of brass.

The 2.5 degree taper insert is made from steel.

We can now regrind the cylinder with fine diamond grit paste.

After the grinding process the surface has a mat like finish.

In several stages the cylinder is honed smooth, to improve the surface finish it is lapped with 1 micron diamond lapping compound and later polished. 

The rear face of the crankcase was not entirely flat so some grinding is required here too.

Still a bit more grinding is required at the top.

Below we see the head after milling the hexagonal a bit; before it was badly worn, now its the right size for a 7 mm socket.

The engine is now reassembled however we find that some final fine lapping is still required to get the right fit.

My cat Puckie senses that its time to go away and hide again, because pretty soon things are going to get noisy around here.....another test run.

After many hours of work we are finally ready for a first test run of Jose's rebuilt Stallion.

Watch the rebuilt 1/2 A stallion do its first bench run.

https://drive.google.com/file/d/0Bw2P1xgqAWCuMlBxMWdVTk9BZE0/edit?usp=sharing

Jena 1cc model diesel rebuild project

ENA Motor 1cc Version II

Technical data:

Model JENA 1 Version II Manufacturer VEB Carl Zeiss, Jena, DDR Distributed VEB Carl Zeiss, Jena, DDR Series / Serial No. s / n Year of manufacture 1960 Displacement 0.99 cc (0.060 cu. In.) Diameter 10.7 mm. (0.421 in.) Career 11.0 mm. (0.433 in.) Power class Diesel Time 2 Type of carburetor Fixed (no speed control) Admission Subpistón (side port) Inner bearing In Front Outdoor BeIfaring In Front Crankshaft to crankcase In Front Crankshaft on bronze NA Fuel Ether / Petroleum / Oil Condition Poor Comments Motor built by Carl Zeiss optics manufacturer.This model is characterized by the admission subpistón (piston skirt serves as a valve). It also has ball-bearing crankshaft and radial transfer.

 This example is equipped with a spring starter, the users manual and the box which it came from as purchased new.

 All models of the Jena line of model engines are sold in boxes resembling the one pictured below.

It is very difficult to acquire a perfect example of this rare engine; even the one from my collection has some nasty looking scuff marks on the rear crank case cover.

 Below are shown the other Jena engines in my collection.

 This story is about the rebuild of my friend Jose's engine that on inspection has a lot of problems: a broken crank shaft at the output shaft; excessive play; piston not moving freely and poor compression.

 Below is shown on top my running engine and below Jose's rebuild basket case.

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Jena 1 cc model diesel rebuild project