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Esher & District Model Flying Club

President: Dave Ward Esq
Vice Presidents:. J.S. Barker Esq.

COMMITTEE

Tony Major: Chairman	Fred Clarke: Secretary	Dave Hodges: Treasurer
Tony Fuller: Vice Chairman		Geoff Ward: Safety Officer
Keith England: P.R.O. keith.england at connectfree.co.uk	Click Here for March's Newsletter	Alan Dobson: Social & Membership Secretary Bigdobo at aol.com

September 2004

From the Chair

Well here we are nearing the end of the summer holiday season and the recent weather has been as unpredictable as usual.

Attendance at the monthly meetings has been poor, understandably so because of having to share space in the refectory at Nescot and being unable to fly in the evenings in April and May.

Eventually however our insurance was 'approved' by Nescot's insurers and some flying took place in June and July. See below for details of our return in September.

Flying at Merstham - we have had many good sessions from 10th April to date, and we continue there until the 30th October.

Now for some good news-----------!!!

New Flying Field - I am very pleased to report that Kit Wallis has introduced us to a friendly farmer (Chris) who is prepared to let us use his fields situated near Downside.

Our thanks go to Kit, who will in future be exempt from club subs for the duration of our use of the fields.

Chris has flown full-size for years and has R/C models. We look forward to him joining us as an honorary member also to seeing him at the field when he can spare the time.

This site will be our Winter/Spring field. We are planning to prepare the landing strip in time to commence flying there on Saturday, November 6th. Volunteers are needed to help prepare the strip during the two weeks before hand; please let me know if you can help.

A set of rules relating to the use of this field will be sent to all members - please read and abide by them.

Figure 1 - The New Field looking East - Pits will be between the two trees. M25 in the distance.

Clubroom - As you know we have been temporarily based at Nescot but, commencing Wednesday 8th September onwards we will return to the previous facilities at what was the London Fire Brigade Sports and Social Clubhouse. The room we will be using is smaller and the cost has increased from £15 to £20 for the evening (7:30 to 10pm). We will have to see how it works out. Flying will be allowed on the field as previously.

Competitions - Only two league comps have been held so far and there seems to be some lack of interest in them, probably due to the crosswinds that have prevailed and the surrounding trees which many members find intimidating. I feel sure that members will feel much happier about taking part in the new field.

Finally, lets hope that the weather will be kind to us during the coming months.

Keep them flying!! TM

Diary

06/11-Sat First day at new Winter Field.

10/11-Wed AGM

27/11-Sat Trains Planes and Automobiles Exhibition.

04/12-Sat Club Christmas Meal –Surbiton Golf Club approx £17/head please give your name to a committee member ASAP if coming.

AGM Wednesday 10th November

This will be held at 7.45 sharp. Please try to be there.
Apologies for absence
Minutes of 2003 AGM
Matters arising
Chairman's report
Comp Secs report
Newsletter editors report
Presentation of awards
Treasurer's report
Election of officers
Fixing of subsAny other business

Please let the Secretary know of any nominations for the committee.. Keith

Trains Planes & Automobiles

The biannual Trains, Planes & Automobiles exhibition is upon us again and I've volunteered the club to take part. This is a modelling exhibition held at Holy Cross Church, Adela Avenue, Motspur Park on Saturday 27th November from 10 until 5pm. This year it will be somewhat larger as we have been given permission to use the church as well as hall for the exhibition.

As ever I would be grateful for the loan of nice models to put on display and, at least a couple of volunteers to help on the stand - lunch, tea & coffee will be provided. Models can be taken to the hall on Friday night and retrieved on Saturday at 5pm, they are fully insured and guarded while at the Church. It would be good if we could also display and perhaps run a gas turbine engine? Please let me know if you can loan a model or help on the day Keith

Stalling

I was very pleased, at our August club evening, to be asked by Bert Choney to fly his, geared electric, Flair Harvard. As an IC powered model this Harvard is a very good flyer, but 14 sub-C cells add quite a bit of weight (nearly 2lbs/1 Kg) so I knew the wing loading would be high; it also has quite a lot of wing taper and no washout so tip stalling was a possibility. I'd need to be careful with it.

Holding up elevator to prevent it nosing over I opened the throttle and was caught out by the acceleration. It got airborne before I could ease off the elevator and promptly started to drop one wing and then the other. Picking the wings up - helped by the coupled aileron/rudder- I pushed the nose down it then accelerated away cleanly.

At a good height and having trimmed the model I tried a loop; going vertically up it suddenly veered to the right and the loop changed into a wingover. I pulled out of the dive and it promptly went into a right-hand spin, recovering from the spin I pulled out of the dive very carefully - I wasn't high enough to get away with a second spin. A much bigger loop completed perfectly.

By now I was getting worried about landing in one piece so, again with plenty of height, I throttled back and got a feel for its slow handling and how it behaved just before a wing dropped, I now had a good idea how slowly I could safely fly. It was a relief to find that the landing, with a trickle of power, was a non-event; the Harvard touched down cleanly on its main wheels and rolled to a halt. An exciting flight and very satisfying to land it well! A tiny amount of wash-in on the right wing appeared to be all it took to make it behave like this, showing how a higher wing loading can make quite a difference.

There have been a lot of stalling related crashes recently. The reason for telling this story is that there are a lot of lessons to learn from it. I made some mistakes that got me into difficulties but, ultimately, I did the right things to ensure that I gave Bert his Harvard back in one piece:

Throttle – should be opened progressively during the take off run. Opening it too quickly can easily catch you out.
Wings dropping - especially both wings and coupled with the feeling that you have lost all aileron control is a sure sign you are on the edge of the stall. The ONLY way to recover is to get the nose down to increase speed; if this means the touching the ground then so be it - you'll probably break a propeller but if a wing drops and hits the ground you'll wreck the aircraft!
At low speeds - particularly close to the ground try to pick up a dropped wing with rudder rather than aileron (or at least rudder and aileron), Use of ailerons will stall the wing more violently. Typical scenario is: the aircraft starts wallowing, the pilot becomes so busy with the ailerons he forgets down elevator, the ailerons become less and less effective until, suddenly, the 'plane rolls right over inverted and spins or dives towards the ground. The pilot certainly remembers the elevator now and gives full up ensuring it stays stalled until it hits the ground.
All aerobatics - with a new or unknown model - should be done at least two mistakes high (two spins plus recovery height!)
Slow flying and investigation of the stall should be something you all do with a new model.
Once an aircraft is trimmed and you are happy that the C of G and control response is OK, spend some time at a safe height getting a feel for the way it behaves close to the stall. Many flyers don't like doing this because it feels like they are not in control so they think it dangerous. However recognising that you are close to stalling and getting the nose down will one day save your model.
By the same token you’ll eventually break your model if you keep landing too fast. If you know how it behaves when flying slowly you will have more confidence and control when on the approach to land or after engine failure. Keith

Spins

Which brings me on to spinning!

Last October I discussed spinning an aircraft but I didn't discuss how to get out of a spin once you are in it (sorry!). I've seen a couple of aircraft spin into the ground after engine failure recently so I think I'd better put that right! (Of course had they recognised that they were close to stalling they wouldn't have got into a spin in the first place!)

For most models (i.e. well over 90% of them, those that are not heavy scale types and/or where the centre of gravity is too far back) all that is usually required is to close the throttle and centre the controls. The 'plane should come out of the spin within a couple of turns. Allow the aircraft to gain speed and gently pull out of the dive before applying power to climb back up or setting up a glide to land.

If the aircraft is still spinning after a couple of turns, or you need to recover as quickly as possible, then the 'standard spin recovery procedure' for full size aircraft is correct for most models as well:

Close the throttle and keep it closed until a safe airspeed has been regained.
Centre the controls and make sure you keep the ailerons centred.
Identify which direction the aircraft is spinning in (however with a model you may not be sure which direction the aircraft is spinning so, if unsure, leave the rudder centred and skip to down elevator below.)
Apply full opposite rudder and then pause
Progressively apply down elevator until the spin stops.
Centralise the rudder.
Level the wings, allow the airspeed to increase and ease gently out of the dive.
Open the throttle and climb back to a safe height.

Speed will still be very close to the stall when the aircraft stops spinning. If you pull out of the dive too quickly the aircraft will go straight back into a spin.

The throttle should not be opened until a safe airspeed has been regained, as the engine torque is likely to tighten the spin further. However for light models, and only if all else fails, a short (1 second) burst of power with full opposite rudder may just break a reluctant aircraft out of a spin. Keith

A New Club Record?

I've often though that model pilots would make very safe full size pilots as they have seen or experienced almost every type of incident that a full size pilot would get to experience just the once! Of course, the most common full size incident - colliding with high ground while flying in cloud - just isn't likely to happen to us!

Well congratulations to Dave Roberts who achieved just that a couple of months back.

It was a heavy overcast day and Dave was flying his Spacewalker quite high. Suddenly, a big lump of very low cloud came over and he lost sight of his model. Pushing the nose down, he attempted to dive out of the cloud. There was only just time to see a streak of yellow and red, when it did eventually come screaming out, before it left an impressive crater in the top field.

What should he have done? Remember the last newsletter " When in trouble, close the throttle on the double!” To have any chance of spotting the aircraft when it comes out of cloud you have to know where it is. The only way to do that is to stop it flying or it could be half a mile away in any direction before it is below cloud. This is where the spin has a real use. Tony M and I took our planes up into the cloud to demonstrate that by spinning the aircraft it would come out of the cloud quite close to where you last saw it and descending relatively slowly - most definitely NOT what you would do in a full size ‘plane! Keith

Tail Dragger or Tricycle Undercarriage?

I sometimes get asked which is best, and questions like "Can I move the wheels further forward to stop the aircraft nosing over?"

It is easy to think that 'old' aircraft are tail draggers and modern aircraft nose wheel (or tricycle) undercarriage. In fact each has its place and tail wheel aircraft are still manufactured. It is modern airfields that result in tricycle undercarriages being preferred and thereby hangs a clue to why.

Tricycle undercarriages are:

Heavy and high drag.
The nose wheel is easily damaged (If you ever learn to fly on a Cessna 152 the instructor will probably show you what holds the nose wheel on (four small steel tubes!). You will never allow the nose wheel to touch on landing after seeing that!)
Propeller clearance is low.
Rotating (Lifting the nose for take off) involves pushing the tail down increasing the weight on the main wheels. This means that tricycle undercarriages perform badly in long grass or soft ground and can even fail to reach take off speed. The wheel loading on a tail dragger continually reduces during the take off run reducing the wheel drag as it does so.
Generally, for the above reasons, ground runs are longer, unless operating off a paved surface, and take off speeds are higher.
However:
Pilot visibility taxiing and on take off is excellent. (not an issue for us!)
Directional stability (steering) on the ground is much better.
There is no danger of nosing over onto the propeller.
Tricycle undercarriages handle side gusts and crosswinds much better
It is harder, and more skill is required, to taxi, take off and land on a runway with a tail dragger. " Real pilots drag their tails behind them!" says the bumper sticker!

Why is it Harder to Steer a Tail dragger?

Some tail-draggers like the Piper Cub are very well behaved. This is helped by the main undercarriage being low enough that the aircraft sits on the ground in a flying attitude so that there is a good airflow over the tail. Others such as 1^st & 2^nd World War fighters needed long undercarriage legs to clear the huge propellers. They sit in a stalled attitude on the ground (tail needs to be lifted to be able to take off) and airflow over the tail is poor see Figures 2 and 3 on the right:

Four things can make ground handling difficult on a tail-dragger:

1. When the tail is down the fin and rudder are out of the airflow for many tail wheel types - particularly biplanes and triplanes - making the rudder ineffective. However crosswinds and gusts hit the fin & rudder, this results in a tendency to swing into wind (weathercock), which is then difficult to correct. The solution is to get the tail up off the ground as soon as possible to get the rudder in the airflow.

2. Torque and slipstream effects as the throttle is opened also try to swing the aircraft (usually to the left). With rudder authority poor at first, the throttle needs to be opened gently which is at odds with point 1. above!

3. Gyroscopic effects of a spinning propeller (much worst with a rotary engine!) mean, as the tail is lifted a turn (again usually to the left) is induced.

4. With the C of G behind the main wheels any swing on take off or landing is exaggerated as the tail tries to overtake the nose. If the pilot is not very fast on the rudder a ground loop will result.

Figure 2 - sitting in a stalled attitude – Airflow over rudder is clearly disturbed by fuselage and wing

Figure 3 - Tail needs to be lifted for take off – note the down elevator and lower angle of attack

Figure 4 - Swing caused by wheels well ahead
of C of G

I once saw an Issacs Fury land at an air show and do a complete 360º pirouette before continuing up the runway in the correct direction. The crowd thought it an impressive and intentional stunt, but back in the hanger the lower wing main spar was being very thoroughly checked for damage and the wing tip was covered in grass stains; I think the pilot had a few stains to deal with as well!

By the way, the further ahead of the C of G the wheels are the worst this problem becomes. This is why the wheels are as close as possible to the C of G. If you have problems with the plane nosing over then you can try moving the wheels further forward but be prepared to need to be quicker on the rudder to keep it straight – see Figure 4.

With a tricycle undercarriage the drag is behind the C of G and it acts in the opposite way to correct the yaw.

The drag of a tailskid, instead of tail wheel, will also help keep the aircraft straight while the skid is on the ground. The tricky point is then just as the tail is lifted.

If you do have the wheels well ahead of the C of G it is also important that the aircraft sits in a take off attitude on the ground and not a stalled attitude (as in Figure 2) or you may have difficulty lifting the tail, making take off very difficult.

For the ultimate in fun you can’t beat a fully castering tail wheel (as some full size have). If you can keep that straight on take off you really know how to use your rudder!

So which is better? Tricycle undercarriages are heavier and create more drag, but they are better on modern airports where you are very likely to find crosswinds and paved surfaces. Tail draggers are preferable where weight needs to be kept low and operation off of unprepared surfaces with into wind take off and landing can be made.

Scaled up to full size our strip is quite rough and bumpy, tail draggers should win every time. However, we do use runways and take off can often be crosswind where tricycle undercarriages are best. The trick, of course, is to have several aircraft to choose from: fly your Sopwith Triplane on nice calm sunny days and keep the Piper Cherokee for the gusty crosswind days! Keith

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