We receive some marvellous letters at RCM&E but usually have more than we can accomodate in the magazine. Here are some that we didn't have room for. We'll be regularly adding new letters to this page as space in the magazine dictates.
There is a forum thread for feedback and dicussion around these letters, please use the link below.
6/5/08 - Silver Soldering
I came across the article by Peter Miller on your website quite by chance and as someone who is involved in this field professionally I felt that I should make some comments about the article.
1. The term "Silver Soldering" while a commonly used term is not one that is technically correct. The term Soldering, which should be more correctly referred to as Soft Soldering is a joining process that takes place below 450oC. Above 450oC and below the melting point of the metals being joined the joining process is Brazing. The process that Peter Miller refers to in his article should be called Silver Brazing or Low Temperature Silver Brazing. The term Silver Soldering could mean the use of a Silver containing Soft Solder, this is to say a 3.5% Silver, Tin soft Solder melting at 221oC, commonly used for soft soldering Stainless steel and sometimes marketed as a high strength Soft Solder.
The term "Soldering" is also commonly used by Jewellers and Silversmiths, but again the process they carry out technically is Brazing. Jewellers will "Solder" Platinum Jewellery in some applications at temperatures in excess of 1400oC. The upper temperature limit for the Brazing process is the melting point of the parent materials. If the parent materials are melted during the joining operation then it becomes a Fusion Welding process. High melting point metals such as Tungsten and Molybdenum are brazed in some application using pure Platinum M.P. 1763oC as the brazing filler metal.
The terms Silver Brazing or Low Temperature Silver Brazing are the correct terms to use and remove any possible confusion with using a Silver containing soft solder.
2. The use of a "Hot Rodding" technique to apply the flux is one that is not technically sound. Peter Miller indicates that he pre-cleans the joints / parts with a file and sand paper, which is absolutely the correct thing to do. However, having gone to the trouble to remove the surface oxides from the materials they are then heated in air without flux cover. This then oxidizes the parts again, probably to a more significant degree that they were before they were cleaned, before any flux is applied. The correct way is to apply the flux as a flux paste. The powder should be mixed with water and a few drops of liquid detergent that acts as a wetting agent and allows the paste to be painted on as an even coat onto the joint surfaces. There is always a question of how much flux to apply and all I can say is that I have seen many poor joints result from too little flux, but none from too much flux. Flux paste should be applied to the faying surface of the joint and on either side of the joint line up to 25 to 50 mm away if you like. The flux protects the metal from oxidation and makes cleaning up the whole part after brazing less time consuming.
The flux when used as paste also act as a temperature guide, both with regard to ultimate temperature, but also to the heat pattern produced within the joint. Silver brazing is about brining the whole joint area to an even temperature and then alloying the brazing filler metal to flow through the joint by capillary attraction. Having said, evenly to temperature, heat gradient within the joint is also important, since molten brazing filler metals can be encourage to flow through a joint if one end of the joint is at a slightly higher temperature. In the example shown in the article, one would heat the joint evenly to brazing temperature and then apply the filler metal one side of the joint while applying heat to the other side. The alloy should then flow through the joint forming a small, neat fillet build up of filler metal around both ends of the joint.
Returning my comment of using the flux as a temperature guide, a flux suitable for use with a low temperature silver brazing filler should be in the fully molten condition and flowing like water at about 650oC. This is the temperature at which the true Low Temperature Silver Brazing filler metals (Silver Solders) Cadmium containing or Cadmium free filler metal will melt and flow. This is well below the red heat that Peter Miller indicates in his article. This could mean that either Peter is not using a truly Low Temperature Silver Brazing filler Metal or he is overheating the joints as he has no flux present to act as a temperature guide.
There are other technical points that could also be made, but for those of your readers interested in understanding the process of Low Temperature Silver brazing I would suggest that you direct them towards our website. www.jm-metaljoining.com. If they look in the technical section of the website they will find a video presentation on the "Six Steps of Successful Brazing" that I am sure will prove a beneficial guide to anyone who want to braze or Silver Braze.
Jack Willingham by emial.
11/3/08 - Yak Back
I need to complain about some comments made in the review of the Yak 54 by Chris Broad in your recent issue. I should give a bit of background first - I am a retired Aeronautical Engineer (worked at McDonnell Douglas on the F-15 and F-18) and a life long modeller. I have written reviews and articles for Model Aviation so I know how easy it is to not write the right thing or think one thing and the fingers go along writing something else. With that in mind Chris says...
"However, the slightest hint of rudder would flick the aircraft into a violent spin - evidence of the designs inherently unstable nature and a distinct advantage for flick based manoeuvres."
The design is not inherently unstable. Quite the contrary, the design is remarkably stable and it has been one of the more modelled designs in recent times. The directional stability of a design is defined as Cn/beta (yawing moment coefficient as a function of sideslip angle). With the large vertical tail the Yak has great directional stability. What the design does have is a very powerful rudder control authority. This is what causes the airplane to flick in spite of the directional stability. The same comments apply to the longitudinal stability of the design. Chris goes on to say.....
"Take-off was again smooth and straight yet still showing a slight reluctance to rotate, which I put down to a combination of the model's features such as the low angle of attack and lack of dihedral."
This statement was just plain awful, sorry Chris. The factors that affect rotation of a design would be the landing gear location, C of G location, design longitudinal stability, wing lift and tail control authority. With the Yak these things have been proven over and over again. The angle of attack of the wing is determined by tail control authority, etc. and is simply a matter of getting a little airspeed and letting the tail rotate the body/wing. With a proven design like the Yak, trouble getting unstuck from the runway is most likely being too nose heavy. Lack of dihedral angle has nothing to do with the ability of a design to rotate on takeoff. Dihedral angle is a lateral/directional factor and will affect roll and yaw characteristics but that is all. Chris says.....
"As can be expected and with its unstable nature, this is an area where the model excels."
Again the models is not unstable, it simply has good control authority which allows it to be flown into the maneuvers. With release of control inputs the airplane no doubt returns to normal flight with no problem (after all it is a Yak 54). That is what we expect from this design, which is stable and controllable. That is what makes it a great aerobatic design.
Chris says....
"as clearly this Yak can bite."
Chris was trying to land and made a heading input with the rudder. From the article's previous paragraph it sounds like Chris was flying with too much control throw and the model tried to depart. Any design has a combination of flight speeds, angles of attack, etc. that determine the control throw limits that are appropriate. We spend a lot of time in the full scale world working these things out. To blame the Yak for this is simply not a fair thing to do. A gentle touch and low control inputs at low flight speeds would seem to be in order. I have seen a lot of Yak models from many kit manufacturers in the hands of a variety of pilots that have bitten no one. Aerodynamics is fun but it is a science and it should be presented as such.
Ben Lanterman, USA by email.
We've asked Chris for his comments and await a reply - Ed.
29/2/08 - Thanks from across the pond
I just wanted to give you some feed back following some recent e-mails we have exchanged. I placed a subscription with EWA magazines on February 5th and a copy of the March issue arrived this morning. That's 23 days! Unheard of over here where a subscription would normally take six or more weeks before you see a copy. Furthermore I'm saving over $58 dollars annually over the bookstore price. Just wanted to say that EWA are living up to the very high standard of customer care that you both have demonstrated in your dealings with me.
Jack Higgins,
Toronto by email.
PS. we are about to get another 5cm of snow in a couple of hours and that will be a total of over 60cm in the past four weeks. I have just finished my EZE-FAN and will be putting the final hardware on my Triple Threat ll tonight so covering will begin tomorrow. Hope to get some flying in on the weekend as it will warm up to 1-degree C.
28/11/07 - Jim Newman wrote following the article on flaps in our special issue. He begs to differ....
"There must be many readers of RCM&E who have flown - or currently do fly - full size aircraft. If so, I wonder how many of them experienced some of the confusion that I underwent while reading FLAP HAPPY in the RCM&E SPECIAL?
Yes! There were some interesting facts given, but one needed to be fairly knowlegable about aviating to appreciate them. I fear that the article contained many inaccuracies that only can mislead the budding R/C pilot.
In my experience in the industry, aircraft design was not a succession of compromises. An aircraft was designed to suit a purpose and if the type on the drawing board was intended for "Low and Slow" duty then that design, in particular the wing, reflected that utility. The addition of flaps, for instance, served only to broaden that type's operating capability.
First of all, let us drop the fancy "paperback expressions" such as "deploy" and use unambiguous terminology, such as Raise and Lower, when describing the use of flaps. An aircraft does NOT need flaps unless the fields, from which it is intended to operate, lack adequate length to accomodate the type. For instance, I can land a Piper Cherokee at its recommended approach speed WITH or WITHOUT flaps. With the appropriate power setting - and once established on the glidepath, following the lowering of full flap - I retrim the aircraft's pitch attitude so that the airspeed indicator shows 80 mph, i.e. I trim the nose UP the desired amount and the airspeed will DECREASE to the value required.
At the other end of the scale in the mid 1950s, I watched a Vickers Valiant four-jet bomber carry out a flapless landing without any drama at all, its pilot maintaining the correct approach speed (on its very flat approach) merely by holding the correct pitch attitude.
As might be imagined, with full flap lowered, the glidepath can be very steep, as shown in the article's Fig. 4. I am NOT required to add power to overcome the drag of the flaps. Neither is my steep approach any slower as Fig. 4 implies. Gravity does all that is required, for the reason that I fly the aircraft at its recommended 80 mph REGARDLESS of the glidepath angle. My job, as pilot, is to ensure a constant pitch attitude that will endow my Piper with a constant airspeed all the way to the selected touchdown point. The CONSTANT AIRSPEED is derived from MAINTAINING
a CONSTANT PITCH ANGLE.
There is an old expression quoted by Flight Instructors...."The stick controls the airspeed.The throttle controls the climb and descent!" The inference being that if the pilot constantly wags the stick back and forth, the airspeed will fluctuate up and down accordingly.It also points out that adding power will cause the aircraft to climb and vice versa.
If I elect to make my approach WITHOUT lowering the flaps, my final approach must be started a much greater distance from the selected touch down point, because my glidepath will be MUCH flatter. Nevertheless, with full flap lowered, I still must trim the Piper so that the airspeed indicator reads 80 mph. NOTE: To avoid confusion, and because there is no relationship been the RPM of a model and RPM of the Piper, I have declined to mention power settings.
Another confusing aspect of the article is the mention of lowered flap reducing the stall speed. True! In my Piper Owner's Manual it tells me that, with the flaps LOWERED to 40 degrees, the aircraft's stall speed is 55 mph. On the other hand, with the flaps UP the stall speed is 64 mph. HOWEVER, those are ONLY reference numbers that will indicate to the pilot that he is coming close to the dreaded stall. NO AIRCRAFT HAS EVER STALLED BY FLYING TOO SLOW. What every pilot is taught, at good ground schools, is that an aircraft stalls NOT because it is flying too slow, it stalls because the pilot has raised the nose so high that he has EXCEEDED THE AIRFOIL'S CRITICAL ANGLE OF ATTACK (AoA) and so airflow separation from the airfoil occurs.
NOTE: Model wings generally stall at about 8 degrees AoA, but a light aircraft wing stalls at approximately 13 degrees AoA. This is why it is so important to fly an R/C model strictly by careful reference to its flight attitude, especially at low airspeeds. Keep the pitch attitude level.... or barely nose up.... and the pilot will never stall the model in level flight. Except for those R/C pilots who are familiar with full size flight, most RC pilots do
not understand that aircraft operate with reference to TWO speeds.
1. AIRSPEED. This is shown on the airspeed indicator in the cockpit. If the aircraft is flying at 100 mph indicated airspeed, that speed indication will NOT change, even if the machine is flying into wind, down wind or cross wind. It STAYS at 100mph indicated.
2. GROUND SPEED. This is the speed used for navigation purposes. It is the speed at which the aircraft progresses across the ground. Timing the aircraft between two points (a known distance apart per your map) on the ground will enable time/distance calculations to be made.
I bring these two statements to the fore because I have seen experienced R/C pilots crash a model in the landing pattern (circuit) because they have NOT appreciated the difference. An experienced friend of mine crashed his R/C giant scale Cub on the downwind leg. It was a breezy day and the model was moving
very fast going downwind. He did not understand that the model was traveling at its usual AIRSPEED plus the SPEED OF THE TAILWIND. To slow the model to what was PERCIEVED to be its usual comfortable speed in calm weather, he kept raising the nose of the Cub until he exceeded with wing's critical angle of attack. The Cub promptly stalled then dived to the ground. The moral is that the R/C pilot must accept and live with that high groundspeed when going downwind. Just keep the model's attitude level or only slightly nose up.
The article made reference to modern airliners being equipped with Fowler flaps. Unfortunately the photo on page 24 showed what apppears to be a Boeing airliner that does NOT have Fowler Flaps. The flaps on the airliner shown are Double Slotted Flaps and here is where Fig. 3 on page 22 is incomplete. What is missing is an illustration showing Slotted Flaps. In the Slotted Flap the pivot points are in brackets projecting well below the wing...as in the Piper Cherokee and most airliners. The D.H. Beaver model shown on page 21 beautifully shows the Slotted Flaps. As the flap is progressively lowered, it opens a slot between the leading edge of the flap and the lip formed by the trailing edge of the wing's upper surface. This slot is not a chance happening. It is a carefully calculated slot in the order of .015 of the wing's chord in width, for example. The purpose of the slot - or slots - being to accelerate the airflow downwards, across the upper surface of the flap, thus increasing the wing's Coefficient of Lift. DIAGRAM 'A' displays what have been the most common arrangement of flaps generally found on aircraft.
Most of the current airliners, such as the Boeing, use such an arrangement except that the flaps are in two sections, one aft of the other so that, as they are lowered, a second slot is uncovered. In the case of the Split Flap, the usual configuration is that example shown in the photo of the Focke Wulf 190. However,
what is confusing is that a photo of an ARF Junkers 87 Stuka is shown and it has that rather untidy arrangement of flaps - and ailerons - suspended below the wing's trailing edge. This seems to imply that this arrangement is another example of Slotted Flaps. However, when they are lowered they DO form a slotted flap. However, the correct description of this form of flap is External Airfoil Flap and was used, not only by Junkers, but also by Miles (on the Messenger for example)and also on the Auster mk 6.
A true Fowler Flap slides rearwards and out of the wing, lowering only about 3 degrees until the flap is extended most of the way. Only then does it commence to turn downwards. Thus not only is Fowler's flap used to increase the Coefficient of Lift, but it is also a wing AREA INCREASING flap. The most famous aircraft to use such a flap was the Lockheed P-38, which used the initial 3 degree setting to increase the wing area and lift hence the maneuverability
during "dog fighting". The Fowler flap uses a pair of roller bearings, on each end of a flap section, that run in complex, dual machined tracks. The tracks then govern the position of the flap leading and trailing edges during their movement aft. Lockheed's Constellation airliner, of the 1950s, also used the Fowler flap.
A very similar flap, often misidentified as a Fowler, is the Fairey Youngman flap fitted to the Westland Wyvern and Fairey Gannet. The flap is similar in action
to the Fowler, but it is suspended on pairs of swinging links.
Another erroneous statement is that, "..... it's much safer to start finals over the strip.....". This reveals to me the lack of understanding of the recommended
airport landing pattern. Aviation authorities, on both sides of the Atlantic, recommend that a square pattern be flown at all times. For
"full size" pilots this enables one to keep other aircraft, that are flying in the pattern, in sight at all times. For the RC model pilot, it enables him to view the pitch
attitude of the model at all times. A landing pattern may be flown either left hand (anti-clockwise) or right hand (clockwise) as conditions dictate. Usually it is
dictated by the direction of the prevailing wind and also to prevent models from overflying the spectator and pit areas....the latter being a STRICT "no-no"! The
diagram clearly shows the landing pattern and identifies the individual legs flown. Note: FINAL APPROACH always is the leg that descends to the touch down point.
It is while the model is on the DOWNWIND LEG that the power should be reduced to about 3/4 of full power, the retractable landing gear (if so fitted)should be lowered, followed immediately by ten or fifteen degrees of flap...all in that order. It is at this point on the downwind leg, with the side view of the model
plainly in sight, that one must retrim the pitch angle to slightly nose high, i.e. enough to prevent the model from sinking. THIS is why it is advantageous to fly
a fairly long downwind leg....to give one time to take care of those chores and assess the pitch attitude of the model.
It is my own preference to fly the BASE LEG in this condition, merely because one needs to concentrate on when to turn on to FINAL APPROACH...or "Final"
as it is usually termed. Once aligned with the runway, power may be reduced to an amount that will provide a STEADY RATE OF DESCENT that will bring the
model to the touch down point. It is once he is established on final that the RC pilot will find that he is holding the stick back slightly to prevent an excess of
sink rate. At this point the elevator trim lever should be reset to raise the nose slightly and so dispense with the need to keep rearwards pressure on the stick.
With the model nicely in trim, if the flyer finds that the model is losing height too rapidly and might land short of the runway, then he should ADD A SMALL
AMOUNT OF POWER....enough to SLOW the rate of descent. Under NO circumstances should he attempt to "stretch the glide" by holding the stick back.
A beautiful giant scale B-25 was destroyed in my sight, on the edge of the field, by the pilot stretching the glide and ignoring shouts from all present to
"Add power!" The aircraft stalled and rolled over into the ground.
If the flyer finds that he seems to be overshooting the chosen touch down point, the remedy is to REDUCE POWER SLIGHTLY to INCREASE the rate of
descent. He need do NOTHING ELSE else except to MAINTAIN THE HEADING TO THE RUNWAY. Another old flying school expression is that a landing is
won or lost on final. A final approach, with a wildly fluctuating aircraft attitude and airspeed, usually cannot be rescued and so a bad landing inevitably follows.
From all of the above instructions concerning the use of flaps, it can be readily seen that nowhere does one ",,,,battle against their effect...." and nowhere is
a model "hanging on the flaps" if the final approach is flown correctly. To "hang on the flaps" is to invite a stall at low altitude. Another very good reason to NOT put the
model in that "flap hanging" situation...especially if it is a heavy scale model....is that one could well find oneself in "Coffin Corner". That is where, with full flap, the
airspeed will be so slow that control surfaces are almost ineffective. Therefore, on sudden application of full power the heavy model is slow to accelerate, control
will immediately be lost.... and the model will Torque Roll onto its back and dive into the ground. I have witnessed that happen more times than "I could shake a stick at!"
What is so sad is that the article should have covered U-control models and gliders in separate articles, because incorporating all three has lead to distraction
and confusion. The business of flying a powered RC model, equipped with flaps, is complex enough on its own, requiring a thorough understanding of the proper
technique of flying the landing pattern and subsequent final approach. One could not do better than emulate the full size techniques which...as a Private Pilot I do.
Another remark on page 23 referred to, "...a nice floaty flare....". On an RC model such a "floaty flare" indicates that the model is landing too fast - and so is
continuing to fly until the airspeed falls to a value that will allow the model to contact the ground. Every weekend, at the club field, one can see models
"kangarooing" down the runway as the R/Cer "pump handles" the stick back and forth, desperately trying to flare. Each time the pilot pulls back on the
stick the model climbs because of the excess airspeed. Naturally, he pushes the stick forward again...and so it goes on until the model eventually contacts
the runway, the ensuing bounces often ending in an undignified "nose over" or a damaging "cartwheel".
A useful technique is that, when the model crosses the runway threshold, the model should be levelled about 6 inches above the ground and HELD LEVEL.
The RC pilot's focus should now be on the wheels and, when it can be seen that the model is sinking slightly, it is a sure indication that the airspeed is rapidly
decaying. Only now should the pilot commence to slo-o-o-owly sque-e-e-e-ze back on the stick, still watching the wheels until they - ever so gently - "brush" on
to the grass. Attention now must immediately shift to maintaining directional control.
In another article entirely, concerning the Flair Bristol F2b Fighter (Brisfit) in the same issue of RCM&E on page 13, I came across a statement, "Instead of the downward ailerons lifting the wing, their combined drag can produce the opposite effect and induce aileron reversal." This is a totally erroneous statement. First of all, aileron reversal is due entirely to the wing lacking structural stiffness, such that a down going aileron will
exhert enough force to cause the wing to physically twist in the opposite direction. The up going aileron will twist the wing, to which it is attached, in a similar manner. This happened on the Bristol Racer monoplane of 1917 and necessitated the fitment of upper and lower bracing wires, between the very thin wing and the fuselage.
One glance at the photo of the model in the lower right corner of page 13 told me all. The ailerons are rigged with absolutely NO DIFFERENTIAL at all. It is readily apparent that both ailerons are moving with the same amount of deflection. It is a basic aerodynamic fact that a DOWN going aileron will produce
considerably MORE DRAG than its up going companion on the opposite wing. What that model Brisfit was suffering was ADVERSE AILERON YAW.
That model would never have left my own work bench without differential being built into the aileron control circuit.
Building in aileron differential is so easy to do. All it entails is drilling pushrod holes offset from the regular holes on servo wheel and using aileron bellcranks that are made with an included angle of 120 degrees or 60 degrees between the arms. Such cranks are available and will produce more UP aileron than DOWN, when correctly inserted into the aileron control circuit. The adverse yaw on the full size Tiger Moth would be traumatic, except that the aileron bell cranks are constructed to provide aileron deflection in the amount of 10 1/2 degrees of UP....but only 1 1/2 degrees of DOWN! Even so, it is advantageous to roll into a turn leading with a healthy amount of rudder deflection first. The Slingsby T.21B two seat glider was similar in its handling.
I hope that the foregoing will have cleared up some misinformation for the readers.
Jim Newman by email.
Thanks Jim, Just for information, the writer has full size flying experience and the article was an attempt to introduce flaps to beginners. It was not an attempt to re-write the manual and was simply intented as an introduction for the club sport flyer encountering flaps for the first time. Peter Lowe (Bristol Fighter) is one of the best pilots around and simply prefers to use his rudder manually when flying as he said himself in the article -Ed.
7/11/07 HINTS AND TIPS
I enclose a pic of a couple of low-tech ideas that I hope you might consider for RCM&E Hints & Tips page.
Left, For marking bearer positions, etcetera, in hard to get to places inside a fuselage or elsewhere. A pencil mitred to 45 degrees and epoxied.
Right, For free and highly durable hinges, cut them from your old floppy disc plastic inners. They're very tough and can be epoxied.
Pat Quinn by email.
24/10/07 - ENGINE VALUE ?
Back in the mid-90's I bought a Russian built AME .061 non-throttled glo-engine from Northern Velocity (Norvel). This is pre Big-Mig and is the more powerful version.
I never used the engine and it remains pristine and new in the box.
I understand these engines are reasonably sought after in the market place and would be obliged if you could give me an inkling as to its current value. As I have no use for it I am contemplating selling it.
Many thanks.
John Chant, Auckland, N.Z. by email.
We've no idea John but if any readers know?
10/10/07 - THE OHLSSON AND RICE '29' ENGINE AND THE COLLAPSE OF THE COMPANY
The Ohlsson and Rice (O & R)'29 as pictured in the weekenders column by Alex Whittaker in the August 2007 edition of RCM&E was first produced early in 1949. Despite being advertised as 'all new', its design and overall appearance followed closely that of its immensely successful predecessor, the '23' whose starting, running qualities and longevity had made a contribution of pivotal significance to the high standing of the company. The '29' displayed features such as:
A staked- on (and, therefore, non - removable) cylinder head which was decorative rather than functional.
A cylinder which was a spot welded at 2 points into the crank case. This made the engine virtually incapable of being dismantled and re- assembled without specialised equipment unavailable outside the O & R factory. Only front housing could be readily removed.
The piston, with its intricately formed crown, being drawn as opposed to being cast and machined which was the more usual production method.
The use of highly polished, top quality alloy castings for both the front housing and the crankcase, with substantial finning on the underside of the latter.
The crankshaft being mounted on both a roller and bearing and a plain bearing.
Extremely fine gauge finning on the steel cylinder, with its appearance being further enhanced by a heatproof gloss black paint finish.
For the spark ignition variants, the provision of a brand new and advanced type of ignition timer, called the "adjustomatic".
Note: The '29' shown in the RCM&E article has been fitted with an earlier type of timer rather than an original "adjustomatic". This could, of course, be for a variety of reasons. However, this engine is shown equipped with a glow plug as opposed to a spark plug, so that a timer is of no relevance if it is run in this configuration.
At $12.95, the demand for the '29' was huge and production went into overdrive at once. O & R had earned and enjoyed enormous success since well before the second world war, becoming one of the biggest, most diverse and most prestigious companies within the entire model world. It had a reputation for excellence throughout its wide product range which included propellers, fuel (for both glow plug and for spark ignition engines), glow plugs, marine and car versions of its aero engines and even an all-metal race car.
The enormous Los Angeles factory had reached a production level of very nearly 1000 engines everyday and, in the summer of 1949, with the launch of the '29' there was no sign of a cloud on any horizon. Work was even in progress on a pair of new engines - a '33' as well as a 1/2A of totally fresh design. The future was looking very bright.
It was at this point that things began to go downhill and very rapidly too. The new '29' had been marketed for use as either a glow plug or a spark ignition engine, but users found out immediately and dramatically that is was not sufficiently strong to operate with the enhance power output of a glow engine - the connecting rod was bending. This component was, after all, no more than an aluminium diecasting whose design and form followed very closely that of the '23'.
Engines damaged through perfectly normal use were being returned to the company in ever-increasing numbers for warranty repair. There was something of an initial knee - jerk reaction by O & R as it faced this unprecedented situation whereby it seemed to have produced a failure. The answer was a redesign of the connecting rod and its fabrication on forged steel to eliminate the bending. Fitting this new part though proved catastrophic.
Its very rigidity placed excessive strain upon the two welds holding the cylinder to the crankcase, so that either or both welds would break, allowing the engine to tear itself apart. Wrecked engines with cylinders wholly or partially blown out of their crankcases deluged the factory, again for action under warranty. The awful truth was that there was little point in replacing them with factory fresh identical versions because the design defect was so fundamental that the replacements would also rapidly fail and have to be returned yet again.
Confidence in the company on the part of wholesalers, retailers and users had been irreparably damaged. Sales of O & R products abruptly came to a halt, the company's income ceased simultaneously and yet its many large running expense continued to accumulate. To compound these difficulties , the reasons for the failure of the '29' became the subject of much acrimonious argument between the company's founders, Irwin G Ohlsson and Harry T Rice. Their partnership of more than 12 years was dissolved in very short order. Ohlsson abandoned the company to Rice who continued as best he could, but never managed to generate more than a fraction of the sales previously experienced. O & R had disappeared completely from manufacturing engines for model aeroplanes by the early 1950s.
This is all, of course, no more than history, but there may be modellers today who are unfamiliar with the story and who will be interested to hear it. That one of the worlds largest manufacturer of model products should be so swiftly destroyed, simply through producing an innocuous looking engine born with a sound pedigree, is no everyday occurrence.
Furthermore, although O & R engines did not often appear in Great Britain during the years just after the second world war and would not, therefore, be altogether familiar to the majority of the people here, they were an integral part of aeromodelling scene, took major roles in outstanding achievements and were to forefront of technological advances.
As an example, it may be surprising to the F3D fraternity to find that prop-hanging is neither a manoeuvre which has been perfected within the last decade or so, nor is it the sole province of the R/C flyer. It is now approaching 60 years since prop-hanging was routine to the late great Jim Walker in his remarkable control line sabre dance - using the O & R '23' spark ignition engine - with no R/C throttle, just variable ignition timing.
Jim even incorporated into his routine the gentle and impeccably controlled descent of his prop-hanging aircraft until the pin fixed to the rudder and protruding 3/8" burst a balloon tethered on the ground.
Hordes of other flyers were soon following his example. That there is nothing new under the sun rather springs to mind. In addition, Jim often flew 3 control line models simultaneously - with one control handle in each hand and the other handle mounted on a specially designed hat. All 3 were under total control and, again, he was using O & R engines. Truly, he was a genuine maestro.
For many aeromodellers, there is much they wish to learn from those many talented people who have gone before. Irrespective of the specific interest which an individual may follow, we owe a large debt to the pioneers in powered model flying who paved the way for our contemporary enjoyment. Amongst those have to be numbered Irwin Ohlsson and Harry Rice even though their names are, quite possibly, not on the tip of the tongue for everyone.
The writer prefers to remain anonymous.
9/10/07 - RETAILER RESPONSIBILITY
I belong to a club that is fortunate to have a military airfield as a flying site. With a mile and a quarter of well maintained runway and acres and acres of grass we, naturally make sure we do not do anything that would lose us the facility.
One evening I was out flying on my own when I saw two people walking across the grass about three hundred yards away, one of them then bent down and picked up a model. I drove over to where they were parked and discovered a young man and his wife with an ARTF Spitfire.
I asked if they had seen me flying . "Oh yes " he said "But we decided to keep out of your way" When I asked why he had not checked to find out what frequency I was flying on I was met with a blank stare. On checking myself I found it was a Park Zone Spitfire on 27meg. I explained that if there was anyone else transmitting nearby on his frequency he would lose control of his model. Then I asked him about insurance , another blank stare, he then came out with a classic "I am in the Para's, I daresay they insure me" The alarm bells were ringing loudly by now. I explained that one of the requirements for flying on the airfield was to have BMFA insurance.
Looking at his Spitfire I pointed out that it was hardly the ideal trainer. " It has to be a Spitfire, they won The Battle Of Britain" He said. I offered to let him fly an Easy-Star I had with me just so he could get some idea of controlling a model, if he got into trouble he could let go of the controls and the model would level itself out . That was no good 'cos it wasn't a Spitfire". I offered to fly his Spitfire and hand it over when it was at a safe height but he could manage, .thank you very much
I explained about the advantages he would have by joining the model club, but he was not interested. I told him about the strict FOD controls on the airfield. i.e If you bring it on to the airfield ,you take it away with you, that includes bits of model , fag ends ,in fact anything. I drove back to where I was flying and as I went I saw his wife running at full speed with the model over her head , she then stopped dead and let the model go. It hit the ground two yards in front of her
How many people are there all over the country, some flying in public parks with children around, flying unsuitable models with no idea of frequency clashes, or that there are different frequency's. They go into a shop and buy a Spitfire/ Mustang/ Thunderbolt or FW190 and come out without the shopkeeper explaining the danger that a model poses or the responsibility that comes with flying a radio control model. He is clearly happy to have made a sale and feels his responsibility stops there. I don't know if any of the ARTF manufacturers put warnings in with the kit but I think it should be mandatory.
I have not seen the Para or his model since so I imagine what looked like a very nice model has sadly been wrecked and the club has lost a potential member.
D. Andrews by email
9/10/07 - ACE MEMORIES
Thank you once again for the recent Chrislea Ace model article. Believe it or not the author of these articles and the maker of this model is known to me. It was back in May 2001 when we met at a Wroughton weekend vintage air show. He and a Brian Metters each flew in with their Chrislea Super Ace aircraft, the first time the two aircraft had been together for fifty years. Brian Metters had to return to base that day. John Rickett, David Partington of Air-Britain and I watched him take off and fly off into the sunset.
John Rickett however, was staying overnight and we planned to meet on the Sunday when he very kindly took me up for my first proper flight in a Super Ace ! It was unbelievable. David Partington took some photographs of the two aircraft which he kindly sent to me. Not having kept in touch, you can imagine my surprise when I received johns first article from you.
It was during 1944 whilst working for the Chrislea Aircraft Co in north London that I was taken off the making of small gearboxes for the Bristol Beaufighter and commenced work on the Ace a four seater family aircraft to go into production after the war. It was designed to sell to the car owning parent who would park his car at the airport, walk his wife and children over to the Ace, step into the level, clear, carpeted cabin. No problems with a tight skirt ! The all round windows, its familiar car like interior and controls. A must for the man about town. Selling as quoted in the very smart brochure for £1,750.00.
Under the instruction of Chris (RC Christoforides) MD & Designer. I made a full size mock up of the cabin to check various dimensions, wooden patterns for the unique control system castings and to build the system into the mock up. Convert a centre lathe to cut the concave half round ends of tubing to sit tight at any angle on their mating fuselage tube and sets of high tensile fixings for the wing roots and struts to fuselage.
It seems extraordinary that the small production run of a small family aircraft with some excellent features, but a controversial control system, should have survived at all. I think it is interesting that 17 Super Aces were made and sold during 1948,49 and 50, the last one in 1951 which I understand is in a Queensland museum in Australia. Even more remarkable that two of them flew into Wroughton in 2001!
After Chris left around 49 - 50, the new owners of the company immediately set about fitting a conventional stick and rudder bar control together with a normal under cart tail skid, they called it the Sky Jeep. A production run of 5 was started in 1950, three were sold the remaining two were scrapped when all production would seem to have been ceased around 1951-52. I left the company when it moved to Clyst Honiton, Exeter in 1948.
Monty Brown, London.
The views expressed here are not necessarily those of the editor.
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