Esher & District Model Flying Club

President: D.A.E. Smith B.Sc. (Eng.), C Eng., F.I. MECH. E.
Vice Presidents: M. Charles Esq. J.S. Barker Esq.

COMMITTEE

February 2003

From the Chair

Spring will soon be here! We have all had a long wet, cold, windy winter but at least it has given you all plenty of time to build those exciting new models for 2003.

Now lets try to bring you all up to date: -

The Christmas Dinner – The majority of members enjoyed this but I heard that some were unhappy although nobody has said why and have not spoken directly to me.

The caterers did a good gob, the venue was special (thanks to Dave H), but we are aware that certain improvements can be made. If we held it there again we would: (a) Put one committee member on each table. (b) Provide an aperitif on arrival. (c) Create a little more space by having only 8 persons per table. (d) Take orders in advance for first course.

Please let me know your views so that we know whether or not to book for this year.

The AGM – A 50% turnout, same committee, a financial loss for 2002 of £607, but, at least we still have a healthy bank balance in hand.

Post Xmas Soar-in – A great success, wind directly on Colley Hill, lots of flying, lots of laughs.

B.M.F.A. – We expect several members to get their ‘A’ wings over the coming months and 4 of our ‘B’ pilots are going to try for the Examiners Certificate. Good luck chaps!!

Fred is also writing to the BMFA to get approval and register 7 volunteer club instructors.

Reigate Field – We are scheduled to switch to this site in May – see diary dates. 

Keep 'em flying and happy landings     Tony Major

Diary

Wednesday meetings are now only once a month on the 2nd Wednesday in the month

Editor’s Notes

I thought that it this year I might ‘theme’ the newsletters by taking a look at the various less common model aircraft types: biplanes, multi-engine, deltas, jets, etc. A number of the newer club members have asked about building and flying biplanes. "Are they more difficult?" etc. so I decided to start with them.   Keith

Biplanes

Although I'll use the term "biplane" everything said also applies to triplanes, sesquiplanes, etc. as well.  (*Sesquiplane = 1½ wings, Nieuport 17 for example).

Any discussion on biplanes as a type is going to be quite a generalisation. For example, the Wright Flyer and Stearman (Picture 1, below) are both biplanes but have little else in common. With this in mind, there are advantages and disadvantages to model biplanes as I see it.

Picture 1 - A Stearman Over The South Down

Lets look my list of advantages first:

• They look good. A biplane is certainly a different thing to see in the sky and many look great. Nothing beats the sight and sound of a 4-stroke powered Scale Tiger Moth or Sopwith 1½ Strutter doing slow, low passes on a calm sunny day.
• They are compact. Two short wings instead of one long one means that many models can fit in the car rigged ready to fly.
• Aerobatics. Not only do biplanes look great doing aerobatics, but the short wings, high drag and, hopefully, low wing loading of aerobatic types, when added to lots of power can mean that they are capable of some amazing and different aerobatics. The Pitts Special (Picture 2 , below) is an obvious example. 

Picture 2 - An Aptly Registered Pitts

• Strong and light. The wings and struts make an inherently rigid box structure. For the same strength as an equivalent monoplane wing it can be built much lighter. In practice most model designers and builders don't make much of a weight saving here which is why the bracing wires are usually just for show!
• Orientation. I think It can be easier to see which way a Biplane is going.

That is some of the advantages, so what are the disadvantages?

• More work. Having completely built one wing, you feel like your just starting when you get to the other!
• Assembly. If you have to take the wings off to get it in the car then there can be a lot of work to get it ready to fly.
• Construction and rigging. With two (or more) wings to deal with the builder has to be a more careful that everything is built accurately, particularly the wing and tail incidences. More on this later.
• Ground handling. The top wing of a biplane catches the wind easily and, in many types the rudder is out of the airflow when the tail is down. These issues can make taxiing and crosswind handling difficult.
• Drag. Lots of struts, bracing wires, etc. can give rise to lots of drag with the result that some types will drop like a stone when dead stick and need very careful handling. However, this will not be much of a problem if the aircraft has been built light and has a low wing loading.

Picture 3 - A Panic. Makes up in handling, aerobatics and strength what it loses in looks! Won’t win an argument with a dumper truck though!

None of the above is intended to put anyone off of flying a biplane. For example, the Flair Puppeteer is very satisfying to build, easy to fly and great to see flying. Both the Panic (Picture 3 , above ) and Toot Sweet (Picture 4, below - A free plan in September '02 RCM&E) are very easy to build accurately, assemble in seconds, are well behaved and very aerobatic. I see also that Ripmax are importing what looks like a nice range of ARTF’s including a Tiger Moth, SE5A and Fokker Triplane.

Picture 4 - Toot Sweet, Just 36” Wingspan, 40­-52, 4-stroke Power.

A bit more about Biplane rigging.

I used to fly with John Pothecary, the then owner of the only surviving Robinson Redwing biplane (Picture 5, below). John's party trick with the Redwing was, in flight, to close the throttle and slowly pull the stick back until the elevator was full up. The aircraft would continue to fly under full control with a very steep angle of descent, perfect for getting into a small field. The Redwing had the lower wing at a greater incidence than the top wing (Known as negative decalage). The lower wing would start to stall and its drag would increase so much that it would pull the aircraft's nose down. Full up elevator would not be enough to counter this. The lower wing would remain on the edge of the stall with high drag while the top wing was still flying. The result was a very safe aircraft that was extremely difficult to spin or stall.

Picture 5 - Robinson Redwing at Shoreham– Would make a great model!

What this shows is that a well rigged biplane can have very good flying characteristics - in this case a bit too good, it would have limited aerobatic capabilities and, probably, a higher landing speed {Not a problem on the Redwing - its top speed could best be described as a leisurely stroll!}  I, personally, would want to reduce that lower wing incidence a bit on a model of it.

Now imagine that that it was the top wing that had a lot more incidence than the lower wing (Positive Decalage). As the aircraft approached the stall the top wing would stall first, the increased drag causing the aircraft to nose up. Full down elevator might check it but as the wing un-stalls the drag would go and the nose would shoot down. At best the aircraft would be a handful at slow speed, especially when landing. The pilot would probably be convinced that the C ofG was too far back and try to correct that.

Negative decalage is not a golden rule; you should always set the wings up as determined by the designer. Airfoil, wing stagger, sweepback and distance between the wings can all change the effective incidence of the two wings. However if you do have problems, or are unsure what the correct incidences should be, a safe starting place is about 0.5º less incidence in the top wing. If you don't have an incidence meter and assuming the two wings are the same chord, this is equivalent to 1/16th more between the trailing edges than the leading edges for each 7" of chord (1mm in 11.5cm).      Keith

After the Winter Lay-up

We seem to be averaging about 20 people a week at the flying field so many haven’t stopped flying this winter! However, if you have not flown one of your ‘planes for a while it is well worth checking the engine, fuel system and batteries before getting it airborne again.

I decided it was time I overhauled and re-covered my Limbo Dancer last week. Inspection of the fuel tank showed that one of the filler pipes had cracked (see Picture 6, below). I have actually seen one fuel tank, left full of fuel all winter, where the brass pipes had split lengthways and curved back – like flower buds opening. It can be seen in the enlarged inset picture below how brittle the brass had become after being left soaked in fuel.

Picture 6 - Brass Fuel Pipe (Inset with crack enlarged)

I had left the ‘plane standing on its nose. We nearly all know that you shouldn’t store aircraft on their noses and we nearly all do it at times! There are two good reasons not to store them nose down:

• Water and exhaust fumes in the engine crankcase will settle on the front ballraces and corrode them – unless you have used a good after run oil.
• Any fuel left in the tank will sit around the tank bung and brass tubing and can damage both.

So, before leaving an aircraft for any length of time, put some after run oil into the engine, turn it over a few times, make sure the tank is emptied and don’t store it nose down. It might also be worth unplugging the battery from the switch.

After a lay up:

Check the engine turns over cleanly – if stiff, squirt some WD40 down the carb and plug hole – if it then feels rough turning it over the bearings should be checked.

Check the fuel tank looks OK and not leaking (seal all but one pipe and blow down it being careful not to let any remaining fuel squirt out.)

Cycle the batteries and visually check them and the leads for corrosion. If batteries are left flat in damp conditions a strange phenomenon known as “Black Wire Corrosion” can occur. It is worth reading about this in the BMFA handbook on page 17. The simplest check I know is to look at the connecting plugs, if one of the gold pins is tarnished the battery lead and possibly switch and leads will need to be replaced or they may fail.       Keith

General News

Planes, Trains & Automobiles exhibition.

This model exhibition, at: Holy Cross Parish Church, Motspur Park, was held again on 30th November. This went very well and raised £625 for charity. A number of members loaned models. My thanks particularly to John Bransgrove and Bert Choney who helped man the stand all day.

Honorary Members

The club, up to now, has had two honorary members, Eric Penn, one of our founder members, and Dave Smith our president.

Last year, two long serving, very active members - both of whom had worked very hard for the club over many years – moved out of the area. They are Jeff Cosford and Stuart Whittle. Jeff was club secretary for some years and PRO before that. He worked tirelessly to move the club towards BMFA affiliation. Stuart was also a committee member for many years and, as a member of the Ambulance Service, first aid at the field and our shows often became his responsibility. Both still maintain an interest in the club and drop in from time to time, Brooklands events, Xmas soaring, etc. so the committee have decided to make them honorary members. We wish them good luck in their new homes and hope to see them often.

Final Thought

The designs we apply to our ‘planes are, as everyone knows, often called ‘Decals’. This is actually just an abbreviation. The correct term is ‘Decalcomania’ – “The process of transferring a design from prepared paper onto another surface”. Not a lot of people know that!

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