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Friday, December 28, 2012

Webra mach 1 R 2,5cc diesel 1954


Data:
Webra Model MACH I
Manufacturer Webra-Fein-Modelltechnik, Berlin, Germany
Distributed by Webra-Fein-Modelltechnik, Berlin, Germany
YOM 1954

Specifications:
2.45 Displacement DC (0.151 cu. In.)
Bore 15.5 mm diameter. (0.610 in.)
Stroke 13 mm. (0.519 in.)
Diesel Power Class
2 cycle
Fixed type carburetor (without speed)
Admission rear rotary valve
journal bearing
Crankshaft on bronze No
Fuel, Ether Fuel / Kerosene / Oil

Comments:
 This is the first successful engine by Webra and opens to the world market. At that time provides very practical solutions and quality materials. Highlight the rear rotary valve, radial transfer of the steel cylinder and the casting piston.

Published on Oct 6, 2012 by valic000 Another nice Webra from my collection.The Mach 1 R were very well made and powerful engines. Also in the early 1950 this design was considered to be a state-of-the-art engine. Together with its very good fits, like all Webra engines he, was a dominating factor with his easy starting and the great power output. There were 2 slightly changes in the head design some years later, but is basically the same engine. I am almost sure,that the head is re-anodized, as the green color is to bright. Also a new tighter piston should be made to give the engine his full power back. The bigger Webra Bully with 3,5 cc ends the line of the Webra diesel range. Still hope one day to get my hands on a 3,5cc Bully. Thanks for interest. lot more great vintage diesels on my channels.More  to come.Stay tuned!

Wednesday, November 14, 2012

Irvine 20 Diesel Rebuild Story


Design History:-
Designed and manufactured as a diesel-i zed version of a nitro glow engine in England in the mid 1980's



Design Features:-
Front through the shaft induction; ABC piston/cylinder technology; advanced design carburetor and bolt on muffler without pressurization tap.


Table of Contents:
ItemDescriptionPage Number
TABLE2
Background History, Specifications, Experiences3
Rebuild section Start of Rebuild5
Parts selectionChoosing used parts for the new runner6
Liner reworkFinishing and tapering liner with special tools 9
New piston Processes and material selection 17
CastingInspecting crankcase and deburring flaws22
Running inMounting, propeller selection and fuel mixture27
Final observationslessons learned and future plans for improvements to the rework process28



The Irvine 20 ABC Diesel Engine

Design History:-
Designed and manufactured as a diesel-i zed version of a nitro glow engine in England in the mid 1980's


Design Features:-
Front through the shaft induction; ABC piston/cylinder technology; advanced design carburetor and bolt on muffler without pressurization tap.

Specifications:-
Displacement 2.5 cc

Observations:-

"This is the latest and, perhaps, the most significant example of the diesel-ization of an existing glow plug engine, in that it was initiated  and developed by the engine's manufacturer. Ever since they began  producing their own motors in 1977, Irvine Engines have specialized in glow engines (the sole departure being their production of the Mills 75 replica) and the fact that Ron Irvine decided to press ahead with the production of this diesel version of the well-liked and very successful Irvine 20 series, obviously indicates considerable faith in its capabilities.

The Irvine 20 has not been extensively redesigned for diesel operation. It has a new crankshaft; otherwise, dieselization is confined to the cylinder head assembly, plus small modifications to the carburetor and silencer".

After describing the reduced-choke carburetor, the author continues....

"The reason for having this much reduced choke area is to enable the engine to be operated without the assistance of an exhaust pressurized fuel system, which is the reason why the diesel version of the silencer has the usual pressure nipple replaced by a screw-in plug.
Why no exhaust pressure feed ? Simple! Exhaust gases condense to form a certain amount of H2O when they come into contact with the cool fuel in the tank. A little water in the fuel does not matter in a glow engine; it is miscible with methanol-based fuel and a small amount can be tolerated...Diesel fuel, on the other hand, is petroleum based (usually kerosene, occasionally DERV). Ergo, the water remains separated and, having a higher specific gravity than that of the fuel, settles in the bottom of the tank, where it may be sucked up by the clunk weight. Not even diesels like running on water. Result: malfunction of one kind or another...".

The author was Peter G.F. Chinn: the author of numerous articles on model airplane engines of his day .


Although it is generally regarded as a fine engine it is not my favorite by far. Looking for a practical RC Diesel to power a Kitty-Wake sport float plane, I settled upon the Irvine 20 ABC diesel to do the job. After a short ground run I made a very bad decision and decided to opt for a first flight. As I recall the flight did not last very long, nor did the poor Kitty Wake. The Irvine suddenly quit and I was faced with the worst of all situations for an RC flyer; a down wind dead-stick landing on a new model. Needless to say the landing didn't go well, ripping away the floats on impact.

That Irvine itself never ran again. All attempts to start it proved unsuccessful and the reason was obvious. There was almost no compression, the once tight engine had gone from lots of compression to none in the matter of a few short minutes (unbelievable!). The engine was thrown into a corner and forgotten for a number of years, until one day I got around to disassembling it for a close examination. What I found was the engine had eaten itself. The piston and sleeve were severely scored, with deep vertical grooves running full length in each. All attempts to find replacement parts (matching piston and sleeve) proved to be impossible so, I thought if I could find a used Irvine 20 engine for parts that would be the answer (not!). The other used Irvine 20's that I managed to find were ringed engines, with marginal compression and I knew from the beginning that they would never start as a diesel.


The Irvine 20 Rebuild Story Starts Here:

The runner was created from parts harvested from three clapped out engines, an ABC diesel and two glow engines. The rebuild subject has a reworked glow cylinder and a new Dispal alloy piston.


The Irvine 20 Rebuild Story Starts Here:
The runner was created from parts harvested from three clapped out engines, an ABC diesel and two glow engines. The rebuild subject has a reworked glow cylinder and a new Dispal piston.




Read how the rebuild was performed


Buy The eBook!

Watch our rebuilt Irvine on the test stand

Sunday, September 30, 2012

German Kratmo10-4 diesel 4cc


 The big Owat 5cc ignition engine

Data:

Model KRATMO DIESEL 4cc (10-4)
Manufacturer Kratzsch Motorbau, Goessnitz, Deutschland
Distributed by Walter Kratzsch, Goessnitz, Deutschland
YOM 1953
Displacement 4 CC (0.245 cu. In.)

Diesel Power Class
2 Stroke
Fixed type carburetor without speed
Induction Sub-piston (port side)
Crankshaft on bronze journal
 Fuel Ether / kerosene / Oil
Like New Condition

Comments and visual material by YouTube Channel Valic000:


Today I run the huge massive Kratmo10-4 model diesel engine.Its in excellent like new condition. I was really quite surprised about its weight,...almost a half kg! Mr.Kratsch made a lot different types of spark and diesel engines from around 1938 up until 1955 approximately s. as far as I know. My engine has in the front a cover,where the main bearing is,so I assume it also housed the contact breaker of the ignition system, when built as spark ignition engine. All his engines can be easy recognized from the style with which he built his model engines.Very massive when compare the Russian K-16 which is also around 4 cc displacement and its weight is only maybe 1/3 of the weight of the Kratmo. But who cared about weight in those days? It was all about power and ease of starting that's what mattered. I also show a Photo of the big Owat 5cc engine. This will also be a very interesting rebuild project someday. A lot parts missing, and damaged, but the compression is great. A nice winter project! I am not sure if this Kratmo-10 4 is ever build as a replica, but this engine could be also the real thing. But it looks so new, its hard to believe that its a genuine engine. Maybe I am wrong here? If somebody knows more about that issue,please contact me. Many more great vintage diesels and rebuild projects on my channel,and more others will be released in the future. Feel free to subscribe. Thanks for watching! 
http://www.youtube.com/watch?v=5HkxQLi65UY

Thursday, September 27, 2012

British PAW 2.5 cc Diesel

Version featured in this [age is the RC engine equipped with a primitive but effective throttle and mufti-positional muffler


Design History:-
Designed and Manufactured in England by the Progress Aero Works, of Macclesfield.

Design Features:-
Front induction; radial porting; simple effective carburetor; radial exhaust ports and exhaust collector ring with variable exhaust muffler positions



Specifications:-
Displacement: 2.47 cc
Bore 15.16 mm
Stroke: 13.67 mm


Comments:-
This model airplane engine was all gummed up and virtually frozen from years of storage after use. After an hour or so of softening the old oil and turning by hand she is shown here all freed up and anxious to run again.

http://youtu.be/fApvpZWAwYk

Monday, August 13, 2012

Russian MK 12B








The similarity of the MK 12 b to the Webra series 2 engine shown below is probably no accident 



Different production runs of MK12 b engines 



Design History:- 
Designed and manufactured in Russia in the mid 1960's

Design Features:-
Early versions featured a removable front housing;
later models featured a single piece crankcase;
rear induction; and
crankshaft supported on ball bearings


Specifications:-
Fuel:Ether/Petroleum/Oil
Cycle:2T
Data
Cylinders:1
Displacement:2,45 cm³
Bore:15,5 mm
Stroke:13 mm
Weight and Dimensions

Other Information
Model Year1980
Manufacturer
U.S.S.R  (C.C.C.P.)
Distributor
U.S.S.R. (C.C.C.P.)


Comments:-
The engine is an example of an early production run (serial number 44) it comes complete with several production flaws and a  lower than average compression, which makes it difficult to hand start. 


Thursday, July 26, 2012

ED Bee MK1



Click the link Below to Browse the Diesel Book
DIESEL ENGINE BOOK



ED Bee MK 1 Diesel
Circa Mid 1950's







Design History:
Manufacturer Electronic Developments (Surrey) Ltd in the mid 1950's;
Distributed by E.D. Kingston on Thames, Surrey, England;
This engine is the very successful MK1 Bee which was followed by the equally successfully MK 2




Design Features:
Diesel power class 2 stroke;
Fixed type carburetor without speed control;
Induction by rear rotary valve;
Non ball bearing crankshaft running in bronze journal bearing; and
Integral plastic fuel tank often missing from well used engines.




Specifications and Data:
Displacement 0.060 cu. in. (0.983 c.c.)
Bore 0.437 in diameter. (11.11 mm.)
Stroke 0.400 in. (10.17 mm.)



Observations:
This was my first diesel engine and it sat in a box for many years before getting around to running it. Installed in a single channel Keil Kraft high wing cabin model controlled via a rubber powered simple escapement hooked to the rudder (one pulse right two left). A perfect recipe for relaxing flying, until faced with a downwind fly away. The engine is pictured here sporting its new Kirby manufactured needle valve assembly and custom compression adjuster made with a special thread to match the thread restoring Helicoil insert that was used to repair the stripped head threads.  See this little gem run on homemade fuel, using a mixture of 33 % Kerosene, 33% Castor oil and 33% Cold Engine Quick Start (Ether) with the remainder Cetaine Boaster added to improve combustion.
It was not easy to start and I found that it was particularly sensitive to both needle valve and compression settings. Where, in the case of the compression, less than 1/8 turn meant the difference between running and not running.


http://youtu.be/H4Px10SPCIs
  



MAKE YOUR OWN MODEL DIESEL FUEL- FREE BOOK SHOWS YOU HOW; GET IT AT THE ENGINE TRADING POST
Download book at;
http://www.wix.com/crockerdh/my-store#!


Monday, July 16, 2012

Uctkam 2.5 cc Racer Diesel



Data:   UCTKAM Model 2.5 D (CSTKAM) Manufacturer U.R.S.S. (C.C.C.P.)
Distributed by U.R.S.S. (C.C.C.P.) MK III Year of manufacture 1995;
2.47 Displacement d.c. (0.151 cu. In.);
Bore 15 mm. (0.591 in.); 
Stroke 14 mm. (0.551 in.); 
Diesel power class 2 stroke;
Fixed type carburetor (without speed control); 
Admission front rotary valve (crankshaft);
Ether based Fuel / Kerosene / Oil;

Comments: One of the great Russian engines of production and quality better than the Meteor. This is a classical configuration diesel, steel jacketed, cast piston, crankshaft and supported in a front bearing in the crankcase.

Design History:
The UCTKAM Model 2.5 D was Designed and Manufacturer in the U.S.S.R. (C.C.C.P.) around 1968; was evolved from the Uctkam-1. to the MK II and eventually the featured engine the MK III which was introduced somewhere around 1995.  

Design Features:
classical configuration diesel;
steel cylinder liner;
cast iron piston;
fixed type carburetor (without speed control);
induction front rotary valve (crankshaft);
ball bearing supported crankshaft; 
schnuerle scavenging engine of high quality construction

Specifications:
2.47 Displacement d.c. (0.151 cu. In.);
bore 15 mm. (0.591 in.);
stroke 14 mm. (0.551 in.);

Observations by YouTube Channel Valic000:
Again another audition of a model diesel from my growing collection.The Uctkam arrive on the russian market around 1995,but I have no exact year. This engine popped up on E-bay some time ago and I decide this time it wil be not let it slip away from me, as I let it get away twice before..on inspection it is a very impressive engine. Its almost an exact copy of the famous Rossi 15. Diesel/Glow engine This was a very successful and proven design for combat and speed racing, that won many prizes. The Uctkam has also ABS piston setup, that will give him a lot rpm output. I am not sure,if the diesels were also sold with the res-o-pipe too.Its not a easy to find info on that issue. I think a res-o-pipe will work in a diesel too, but a bit less impact than in the case of a glow engine ,because of the lower speed and frequency of the shock wave. But it should give provide better filling of the cylinder. All in all the engine is well made to my mind but, maybe a lot people have had some bad experiences with some of the older engines from the Ukraine...that was the past...but today, there are leaders in developing hi-tec engines for competition flyer. Ceramic ball bearings and super alloys like Dispal S226 are only a few examples for using the best materials for their engines. The older engines shoud be checked for dirt and correct assembly, but if you have ``engine hands``...you can get your self a nice runner. This engine should run 30.000 rpm and produce 1 hp. It has a huge venturi and the same thick crankshaft, so it he hits the right rpm with a smaller prop, it should be possible. Maybe I will test this after the engine is freed up. Many thanks for watch my clips. A lot more nice old engine still will be run...here on my channel..please feel free to subscribe. I hope you share the same passion! Ratings and comments are always welcome.
http://youtu.be/gn3S5X5hDsU


Below, watch one of the early MK1 engines (serial no 44) scream something like it did back in those good old days.

Run-in Process for a MK3 Engine shown below

Thursday, June 28, 2012

Aurora K-2.5 Plain Bearing










AURORA K-2.5 engine Technical data: AURORA model K-250

Design History:
Designed and manufactured in Calcutta India circa 1970 by Mr. Suresh Kumar the Great Grandfather of Aeromodelling in India. He also bought the die of Mills .75 and 1.3 diesel engine and the rights to produce the same in India as K75 and K1.3 (The K stands for Kumar, the manufacturer). The Mills engines are  much valued by many Europeans and collectors of Model Airplane Engines worldwide. 

Design Features:
Aurora engines have very high torque and are exceptionally easy starting and handling;
front through the shaft induction;
plain journal main bearing; and
radial transfer ports and exhaust ports.

Specifications:
displacement 2.5 cc  

Observations:
All models have been test run at the factory before dispatch. These engines represent an excellent value and are ideal for general sport flying where reliability and good handling are so important.

 http://youtu.be/_ZRZMcrZAA8


Thursday, May 31, 2012

CS DEEZIL Replica Top End Build Story

The complete story of how this was created  from the crankcase of a CS DEEZIL replica.



The CS Replica bottom end was purchased cheaply on eBay and this is the story of the building of the top end for this item.


The Deezil Rebuild Story or Making a Runner from the Bones


By


Peter Valicek


and


David Crocker





The eBay Auction Page:
Carter DEEZIL NEUF COMPLET AVEC VILEBREQUIN BIELLE BOUCHON ARRIERE ECROUS RONDELLE PLATEAU D'HELICE PIPE D'ADMISSION POINTEAU ET GICLEUR Manque chemise piston culasse bonne base pour construire un moteur personnel



DEEZIL carter complet neuf moteur airplane model engine


Item condition:New
Ended:Apr 06, 201215:29:46 EDT
Bid history:5 bids
Winning bid:EUR 15.50
Approximately C $19.78
Shipping:EUR 12.35(approx. C $15.76) La Poste - Colissimo International See discounts 
 |  See all details
See details about international shipping here. help icon for Estimated delivery date - opens a layer
Delivery:
Returns:
Returns accepted | Read details
Coverage:
Pay with PayPal and your full purchase price is covered | See terms



Watch the following short video highlighting the major challenges faced by the machinist-engine rebuilder 
during the course of this project






Watch the video of the complete story

\
News Flash:
This engine was the inspiration to rebuild a limited number of Gotham DEEZIL engines and offer them to the model engine enthusiast as fine running examples of this interesting relic from the past. Watch here for news on the progress of this project 

Wednesday, May 9, 2012

RCV 58 CD Rotary Valve Glow Engine







Engine Overview:-
The RCV - rotary cylinder valve four stroke engine represents a major advance in model engine design.
Although its moving components (piston, crank, cylinder and rotary valve) are totally conventional,
they are arranged in a radically novel configuration to provide the aero modeller with several key benefits,
whilst having similar handling characteristics to other 4-stroke model engines:-

Design Features:-
The engine still uses RCV's unique rotary valve system - which has only one extra moving component to a 2-stroke and so is easy to maintain. Its ultra low profile, means the height of this engine is approximately 18mm less (compared to OS & Magnum) & the highest point is 14 mm further back which makes cowling much easier than with other engines.

Observations:-
Based  on my limited experience with this engine I have concluded that this engine is a candidate for an on-board ignition system to prevent low throttle engine flame outs and the inevitable dreaded dead stick landing that comes with it. A close look at the manufactures instructions reveals that he highly recommends using an OS type "F" glow plug with this engine: something that I intend to try before going through the expense of installing the on-board ignition system. I have a plan to try this engine in an old-timer Red Zephyr that I have mounted on floats. This plane is a joy to fly but with its present OS 40 2 stroke it could do a lot better with the extra power of a bigger engine, like this RCV.


SpecificationImperialMetric
ManufactureDie Cast
Engine Type4-stroke - Glow ignition
Displacement0.58 cu inch9.5 cc
Max Power (approx.)0.85 bhp0.64 kw
Weight (exc. silencer)17.6 oz500 g
Length4.01 inch104 mm
Height - centre line axis2.64 inch67 mm
Cowling RadiusR70
Propeller shaft diameter1/4" UNF
Practical RPM range @ prop
2,400 - 12,000 rpm
Example prop sizes (2-blade)10x6, 11x6, 12x6, 13x6
Recommended Fuel10% Nitro / 15% Oil including max 6% Castor


Updated Observations:-
All efforts to get reasonable performance from this engine proved unsuccessful  and in the end I came to the conclusion that it was unable to even match the power and performance of the OS 40 2 stroke engine that it was meant to replace. I literally spent hours over a couple of seasons; trying various types of glow plugs, running tankful after tankful of fuel through it, in the hope it would eventually loosen up and begin producing useful runs. I even installed an on-board ignition system which could be programmed to cut in at lower rpm's. Before attempting a flight I had to set the ignition system to be active through out the full running cycle.

Compact Design - 60 size 4C engine with a super low profile making it an ideal power plant for many scale projects

AT 6 Texan with RVC 58 CD Installed




Bench Test:-






Video of RCV CD 58 Flying in a Red Zephyr Vintage Model :-




Main Components






How it Works
At the top end of the rotating cylinder there is a single port leading to the combustion chamber. This is surrounded by a fixed timing ring with three radially arranged ports; inlet, ignition and exhaust. This simple valve arrangement serves the combustion chamber as the engine cycles through the conventional 4-cycles: induction, compression, power and exhaust. Ignition is achieved through a standard 4-cycle glow plug exposed once only during each complete cycle.The rotating cylinder is effectively combined with the rotary valve in a single component hence - RCV - Rotating Cylinder Valve.




This is what Flying Models UK says about the RCV 58.
First off, let's find out what makes the RCV 58 CD tick. The crankcase splits horizontally about its thrust line, with the upper and lower cases being held together by six Allen bolts. Removal of the bolts and gently separating the cases reveals the intricate innovative workings of the RCV. Our next job is to gently lift out the crankshaft along with bearings, thrust washer/seals, prop driver, piston and conrod assembly; all can be removed in one go. Now up to the top rear of the engine to remove the induction manifold and carb, which is held in place by two Allen bolts. The carb is retained on the manifold by a pinch bolt and nyloc nut. Finally, the last piece of the casing to remove is the valve cover, retained by four Allen bolts and sealed with a fibre gasket. Once removed the rotating cylinder can be pushed out from the top downwards; the cylinder is a very tight fit in the bottom bearing so a lot of pressure has to be used. CRANKCASE ASSEMBLY The crankcase is made of three pieces; all are very high quality pressure die-cast alloy, with machining to the same high standard. The top cover is the simplest part with just four shallow cooling fins running from front to rear and four countersunk holes for fastening to the upper case. The bottom case separates from the top and contains half of the engine mounting lugs and horizontal stiffening webs that run from the maincase to the front bearing housing, with a further web running centrally at the bottom. It’s bored for the six assembly bolts and has a chromed steel breather nipple fitted to the front crankshaft housing. Turning it over and looking at it from the inside, there are two grooves at the front for the thrust washer / seals that lie either side of the front bearing and two stiffening webs that run axially across the main portion of the crankcase. The upper maincase contains the other half of the horizontally split engine mountings, stiffening webs and internal thrust washer / seal grooves, along with the six tappings for the assembly bolts. Looking inside one sees a large, very smooth-running lower cylinder bearing, and right at the top the plain bearing / timing bush with its three ports. From the outside the case has a further stiffening web running from just below the heavily-finned cylinder to the front bearing housing. The manufacturers name ‘RCV’ is in raised machine finished letters on the plug side of the case, with the size and type on the exhaust side. Just below the top of the case at the rear is the induction port with two tappings for a short, pressure die-cast induction manifold, which is angled down and sealed by a fibre gasket. Moving around the ‘head’ in a clockwise direction the first point of interest is the port that’s tapped for a standard long reach four-stroke plug (O.S. 4T recommended by RCV). Moving on we reach the opposite side, which has been tapped for the steel exhaust manifold, two lock nuts and a very quiet alloy silencer that’s fitted with a chromed pressure nipple. Rounding up the case right at the very top is the valve / bearing and a very small oil drain hole that exits just below the top of the rotating cylinder.

ROTATING CYLINDER
The rotating cylinder with its built-in valve, is next in line for description. This is machined from a steel billet, case hardened and finished by very fine internal and external grinding. At the bottom is the large helically-cut bevel drive gear, heat-shrunk on to the main cylinder and chamfered internally for flywheel clearance. Just above the gear is the main bearing seat, which has a machined-in oil drain groove. Finally, at the very top of the cylinder is the plain bearing area, which is cut with the single square valve port and has a vertically-machined groove directly opposite for oiling the bearings as the cylinder rotates; this area acts as the combustion chamber.

PISTON, CONROD AND CRANKSHAFT ASSEMBLY
The very short die-cast alloy piston has a machine finish and is fitted with a fully floating, hardened steel gudgeon pin that inserts into the piston from the rear, retained by a small PTFE pad. A 1 x 10mm diameter raised portion on its crown forms a squish area at TDC when the engine is running. The lower skirt has been machined at both sides for flywheel clearance. Looking inside, two large webs support the gudgeon pin and a small, machined recess in the crown caters for small-end clearance. External machining just below the piston crown provides a home for the un-pegged iron piston ring. The conrod is CNC-machined high tensile alloy, with bronze bushing for both big- and small-end bearings. Both bearings have oil holes, the small-end bored centrally at the top whilst the big-end has two holes - one central at the bottom, the other bored through from the top. Actually, there are two further lubricating grooves machined horizontally across the front and rear faces of the big-end. Note, I have not dismantled the crankshaft assembly as the bearing seals, thrust washers and alloy prop driver are firmly pressed together with precision. The crankshaft is from a single steel billet with a pressed-in, hardened big-end crankpin. The conrod is retained to the crankshaft by a steel thrust washer and circlip that locate in a machined-in groove at the rear of the pin. In front of the fully counterbalanced flywheel lies the hardened bevel drive gear for the rotating cylinder. Forward of this is the first of the two high quality, smooth main bearings followed by a seal that is recessed to align with the crankcase breather vent. Moving along is the rear steel thrust washer / seal, immediately in front of which is the second main bearing and final thrust washer. The last part of the shaft contains the Woodruff-keyed alloy prop driver and output shaft. The prop shaft has been cut with a 1/4” UNF thread for the steel prop washer, main prop and split locking nuts.

CARBURETTOR
Of twin-needle design, the carburettor has a pressure die-cast alloy main body that houses a steel throttle barrel with a finely ground surface finish and a bore of 7mm. The latter is fitted with an adjustable chromed steel throttle lever and is bored centrally for the ‘O’ ring sealed brass idle needle. The main needle valve assembly is from chemically-blackened steel, and is fitted with a very positive steel ratchet clip. Last parts of the carb fitments are the fibre washer, sealed barrel retaining screw and chromed fuel nipple. In common with all our engines, the unit is sealed to the induction manifold by a gasket ring and retained by a steel pinch bolt. Operation of the carb was very smooth from the start, proving very easy to adjust and holding its settings throughout the test.

ON THE BENCH
With an O.S. type F plug fitted, initial starting was done with the aid of an electric starter. Once turning the engine started very easily and settled down to a fast tick-over. Opening the throttle to dial in the top end mixture, I kept a rich setting to prevent over-stressing the internals. This engine took a lot of careful running in (as the fits are very tight), using the recommended 11 x 6” prop over a period of 2 hours using the ‘5 minute run and allow to cool’ method at various throttle settings. After this period the engine would start readily by hand, taking no more than a couple of flicks. Throttle response is excellent from the very low idle to full throttle without any glitches, even after idling for prolonged periods. In terms of fuel, consumption is miserly, though RCV recommend to only use fuels containing a 15% synthetic / castor mix, of which not more than 6% is castor; pure castor oil fuels are not recommended as these will gum up the works. RCV also recommend a nitro content of 10% but the engine was found to run quite happily on 5%.

SUMMARY
Rotating cylinder valve engines are unique and a great step forward over conventional four-strokes with no valves, camshafts, pushrods, belts or gear trains to time, break or gum up (in the case of valves). Wear of the 58CD cylinder is minimal, due to the cylinder rotating as the piston goes about its business. The 58CD is the first of the new generation of crank-driven models and has true versatility when it comes to usable prop diameters and pitch. All its predecessors take the prop drive from the engine's rotating cylinder that turns at half engine speed, giving a very limited range of large diameter, high pitch props that can be usefully used with them. This is a very compact, slim engine and, judging from the response it has been getting, this is the one modellers have been waiting for. The 58CD draws lots of interest and admiration wherever it is taken and it definitely has a lot of wow factors that are missing from lots of the other brand of four-stroke engines that we see around our flying fields these days.