September 28

Model Airplanes Flight Checks

This aspect of preparation is absolutely essential and involves both yourself and your tutor if you are fortunate enough to have become a club member.

Buddy Box Tutor
Buddy Box Training in progress

The first thing you need to do for your model airplanes flight check is to familiarise yourself with the fitting of any removable parts prior to flying. This usually involves attaching the wings to the fuselage and installing the flight battery for an electric model. I suggest you practice this a few times at home so that you are completely familiar with the process when you do arrive at the field. Once assembled make sure that you have “Bound” the receiver to the transmitter. Follow the instructions in your radio equipment manual.

Finding The Centre of Gravity (CoG)

The next thing you need to do is to balance your plane. All RC planes have a centre of gravity (CG) this is the also known as the balance point. A plane that balances ahead of the CG point is nose heavy, balance behind the CG point is tail heavy. There is an old saying “a nose heavy plane flies poorly, a tail heavy plane flies once.” A tail heavy plane is very sensitive to rudder and elevator movements making it very hard to control.

So you see it is extreemly important to check that your trainer balances on or very slightly ahead of the CofG position, never behind it. The kit instructions should provide guidance as to the correct position for this balance point. A simple balance stand can be made using small gauge PVC  plumbing tube as in the picture below.

CG balancer

This is constructed using:-

1.5M of straight tube,  4 x corners,  2 x  “T”  pieces and 2 x end stops.

This results in a very cheap but effective balance stand. All you have to ensure is that the two uprights are taller than any anticipated undercarriages you anticipate using. I suggest 300mm (12″) of height should be adequate.

Tip to Tip Balance

Once you have balanced your plane in this way suspend the model by a length of thread around the propeller shaft and another length around the rear fuselage, just in front of the stabilizer. If the plane tends to drop one wing it may be necessary to add some weight to the rising wing tip. so that it balances horizontally. If in doubt get advice from an experienced modeller.

On your first visit to the field it will be necessary for you to discuss your training requirements with the  flight training officer. Please be patient and be prepared to go along with the suggestions made to you and initially accept the tutor appointed to your training. You need his expertise and he needs your co-operation.

As you progress, you will get a feel for your developing relationship so don’t be afraid to talk to the training officer if you have any issues with the appointed tutor. A good working relationship and respect between the two of you will greatly help to speed up your progress over the coming weeks and months.

Initial Overview

Your tutor should make a deliberate and thorough examination of your model to satisfy himself that it has the necessary inegrity to be commited to flight. You should avoid interfering but be prepared to try and answer any questions. Don’t be offended or upset if any amendments are suggested. These will be made only if they are needed to ensure the safely of the model during preparation and flight.

If this should happen and the changes require workshop treatment, don’t be tempted to try and make changes temporarily at the field. Err on the side of safety and be thankful that you will be able to fly another day. Better safe than sorry!

If you are lucky enough to have produced a completely flight ready model, congratulate yourself and prepare to watch your tutor test fly the plane. Don’t expect to take control yourself on this first flight. It will be a real suprise if your tutor is able to satisfactorily trim the plane ready for you to take the controls on this first flight. Normally your tutor will land the plane and discuss with you any adjustments required, both physical and/or digitally on the transmitter.

Prior to this first flight you and your tutor should do a Range Check”. This is essential to ensure that the radio link between your transmitter and receiver is correct and at full strength so that your plane does not go out of range during this first flight.

Amendments Completed – The Next Step

When you have made the necessary changes recommended by your tutor, get him/her to re-check your plane so that he/she is satisfied that all is as it should be. If everything is OK then your tutor should  carry out the initial flight test discussed above. In preparation for this first flight a complete “Pre-Flight Check” should be carried out. You should get into the habit of carrying out this schedule before every flying session in fact you should complete most of this check list before leaving home so that anything requiring attention can be corrected before you leave. The only parts you should leave till you get to the field are any checks to be carried out whilst the engine or motor are running. Let us look at what this entails.

Essential Checks

I suggest you get  a piece of card and create a permanent check list to be carried in your flight kit so that you do not miss anything at future flying sessions.

Pre-Flight Checks
Pre-Flight Checks

 

PRE-FLIGHT CHECK LIST

1)        Check  your Transmitter Battery contains adequate charge. Standard NiMHs do self discharge over time so if this is the type fitted to your transmitter an overnight charge will ensure sufficient juice for your days flying. Long life NiMhs will normally hold enough charge for several flying sessions but do check that you have at least 5volts in a four cell battery and 6.5volts in a five cell version. Some more modern transmitters are able to accept a two cell dedicated Lipo battery giving 7.4Volts. these will last a considerable time and will usually be good down to 6volts (3volts per cell – the minimum cell voltage before irreversible damage is risked to the Lipo).

2)       If yours is an electric model, check that you have fully charged all of your Lipo Flight Batteries. Lipos loose very little charge over time, as a result it is very easy to forget to charge them or at least check that they are still fully charged. A small rubber band around fully charged batteries to be removed before a flight is a good reminder. If you find a Lipo without its band its a good bet you have forgotten to re-charge it.

3)      You should have Cleaned Your Model after the last flying session, especially if its a Glow powered model. A clean model is a an indication that it has not been neglected and has been checked over for problems.

4)      Check that the Landing Gear is secure and that the connection to the steering servo is sound. This is particularly important in future checks after the model has been flown. Most model landing gear takes a considerable amount of abuse especially during training. If a part needs to be straightened after a heavy landings be sure to remove the part before doing so.

5)      Check over all Servo Linkages and associated control  surface linkages. Make sure all screws are fully tightened home. Examine plastic or nylon fittings to make sure none are split or damaged. Make sure the screws in the top of the servos are in place and fully tightened. Never risk a flight if you are in any doubt about the reliability of a servo.

6)     Give all Control Surfaces a gentle tug to satisfy yourself that all the hinges are secure and safely glued in place.

7)     Check ALL Electrical Connections. Make sure all of the servo leads are fully pushed home into their respective receiver sockets. If you have used servo extension leads these should have been fitted with lead locks. If they are accessible check that they are fully locked. If yours is a Glow powered model or an electric model with a separate receiver battery, operate the receiver battery isolator switch a couple of times to make sure it is functioning correctly.

8)      Examine your Propeller and make sure it has not incurred any damage. If you find any such damage immediately replace it.

9)      Generally inspect the model for damage that may have occured during transportation, in storage or during loading into your vehicle. We generally refer to this as “Hanger Rash”!

10)     Back to your transmitter now and check that you selected the Correct Model Memory location.

11)     Finally Double Check Important Things such as

       a) Wing joiner tube fitted?

       b) Aileron servo leads connected and locked before fitting the wings?

       c) Wing bolts fitted and fully screwed home?

       d) In an electric model is the Lipo correctly secured?

       e) Engine and fuel tank plumbing thoroughly checked for leaks or damaged?

Having reached this stage and you have completed your model airplanes flight check you are about ready to throw yourself on the mercy of you tutor but there is one more important thing you need to do.

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