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Posts Tagged ‘scale’

Antonov 225 RC Model Plane

August 19, 2010 1 comment

Hi again!

I’m back from holidays, so hopefully i’ll focus again on updating the blog often.

I found a great model from the biggest airplane – the Antonov 225. Although huge, this is not the biggest Model RC plane, but a good sized model of the biggest airplane. It is EDF powered and the fact that it has a total of six fans gives it a nice sound. The flying style seems pretty close to the original, a good scaled version. Enjoy!!!

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AH-6 – Attention to detail taken to the extreme!

August 3, 2010 Leave a comment

Hey there!

I’m currently on holidays, so the blog will not be updated as often as usual… Anyway, I’m busy with an interesting project for my T-Rex, that I will post here soon.

This post is to showcase a video about an amazing AH-6 scale replica, with details that will take your breath away!!! Enjoy!!!

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Mil Mi-24 Hind Turbine – 2.6 meters of scale perfection!

May 10, 2010 Leave a comment

If you always dreamed with that big huge helicopter with amazing scale detail like the original one, then look at this beauty!

If is a faithful scale version of the Mil Mi-24 soviet attack helicopter, produced by Mil Moscow Helicopter Plant and it is operated since 1972 by Soviet Union military forces, their successors and, since then, by other 30 countries.

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Showcasing Large Scale RC Helicopters

May 10, 2010 Leave a comment

Hi there! In anticipation for this year’s IRCHA 2010 event (to be held in August 11-15th, here is a showcase of some of the models that participated last year.

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Getting Started on RC Helicopters – Part 6 (Learning to fly)

May 10, 2010 Leave a comment

In this (very long) post, i will go through the several stages of learning to pilot a RC helicopter. I can tell you it will not happen without practice and time, so keep your anxiety controlled. But, if you follow these guidelines, you should be able to progress in your skills and soon will be flying like Tareq Al Saadi!

Level 1 – The hover

This first step into flying model helis is probably the hardest part to learn, mainly because you have to do it yourself. Of course an instructor can hover your model and show you the basic controls, he will make it look very easy but at least you know that if he can do it, the model must be okay. On your first attempt at hovering you might wonder what you have got yourself into as it seems almost impossible, don’t worry, its like riding a bike and once you can hover there is no going back.

You will need to fit a training under carriage, there are two types, crossed sticks with balls on the end or crossed sticks with a standard hula-hoop attached, either type is okay and they are usually fitted using cable ties.

Whatever radio you use make sure you have the best gyro you can afford as this will make control of the tail a lot easier. If you can get your hands on a good simulator it will help considerably, and at around £100 if you have a PC, it will be money well spent.

Try to choose a day with little or no wind and make sure you keep the model pointing into wind as this will help to keep the tail straight, all you are trying to do at this stage is to keep the model hovering on the spot at about 1 to 6 inches (25mm to 150mm) high, if it gets any higher, lower the throttle, land and try again. Just keep practising for as long as it takes, it will probably take several visits to the flying field to perfect the tail in hover.

So you can hover tail in and land fairly smoothly. Do not remove your training under carriage; it will still be useful for the next step, which is hovering side on. You can do this by hovering diagonally and gradually turning the model side on as you progress, make sure you practise on both sides of the model, it is very easy to get handed and once you have got the habit of hovering only your favoured side it is hard to get out of.

All the above will take many hours of practise to perfect so take your time and don’t remove your training under carriage until you feel you are ready to do so, you may want to move directly on to learning the nose in hover while you have it on, or you can leave nose in hovering until you can fly circuits when you can gradually fly the model towards yourself until you can stop and hover, which way you do this is up to you as I have seen it done both ways.

Remember, the most important things you will need to become an RC Heli pilot are patience and determination.

Level 2 – First Circuits

Before we get into the flying, set your lower pitch to about minus 2 degrees with 5 to 6 degrees in the hover position and 8 to 9 degrees at the top. It is also useful to set up the radio so that the throttle trim gives you tick over in the middle, idle up at the top and engine cut at the bottom. You should be able to achieve this using the travel adjustment (not the throttle curve) on the transmitter, if not you will have to adjust the throttle servo arm as required. You should now fly the model with the throttle trim at the high position; this will keep the engine revs up when in negative pitch there-by giving more control. As with learning the hover it is a good idea at this stage to get an experienced pilot to fly the model and adjust the trims as required, this will make it much easier for you.

Start with the model tail in, facing into wind, at a height that you are happy with, then hover over to your left side, back to the middle and then to the right side, keep practising this with the tail in then gradually turn the tail to follow the direction of the model and without stopping in the middle. The turns are initiated by applying lateral cyclic (aileron) to produce a bank, together with tail rotor (rudder) to make the tail follow the turn. The amount of aileron and rudder applied will vary according to the forward speed of the model and whether you are turning upwind or downwind. With practise this will eventually become a figure eight with the turns at both ends away from you and at the same height all the way round.

Do not be tempted to fly the model in a circuit around yourself; this is bad practise as most flying sites will not permit you to do this, so all flying should be in front of the pilot and anyway, you will not learn much from this as the model is in the same situation relative to you, all the way around.

Some pilots find the transition from forward flight to the hover quite difficult and avoid this manoeuvre by stopping the model at height and lowering the model vertically to land. This looks very untidy and if you are ever going to fly in a scale like manor you will have to approach at 45 degrees, you will also need to be able to do this to learn autorotations.

To return the model to hover from forward flight reduce power and apply back cyclic, adjust the amount of each control to achieve a 45 degree approach. Ideally the approach should be into wind but make sure you practise from the left and right to avoid getting handed.

As you gain confidence with flying circuits try to gradually make them higher and faster. The height will be useful later when you attempt new manoeuvres, giving you more time to correct a mistake before the ground comes up! Also don’t be afraid to fly on a windy day, I have seen many pilots build up a fear of the wind and you can’t let the weather stop you flying, particularly if you live in the UK.

Remember, the only way to learn is stick time and lots of it.

Level 3 – Autorotation

There are many pilots who advance to quite a high level of flying yet never bother to learn autorotations (autos), a comment often heard is “why stop an engine that is going perfectly well”, fair comment I suppose but what if your engine cuts, chances are you will panic and crash the model. So there is one good reason to learn autos, the other reason being the shear satisfaction of landing your model time after time with no engine power. I having gone through many stages of learning to fly but I found the autorotation the most rewarding of all.

During autorotation the negative pitch will control the glide angle of decent, this will be about minus 3 degrees but will vary according to wind conditions, blades, and forward speed during the auto. I always set my negative pitch to about minus 5 degrees and then adjust the pitch with the stick to get the ideal decent angle.

Before you start, you will need to set your throttle hold switch so that it gives a reliable engine tick over when operated. If your tail is driven during autos you should set the tail blades with no pitch when the hold switch is operated, as there is no torque from the rotor head during autorotation the tail does not need any counter acting pitch. You must be able to perform a 45 degree approach and landing before any attempt at autos. Also make sure you are familiar with the throttle hold switch position on the transmitter, you will need to find it quickly while practising.

To give you an idea of how much power is in the rotor head with no engine power, from the ground, raise the throttle until the model is light on the skids, switch to throttle hold and gently add pitch, the model will hover for a short time.

Start by flying your normal circuits at a safe height, when flying into wind hit the hold switch and apply negative pitch, the forward motion of the model should keep the tail straight, if the tail kicks to the left or right return the hold switch to normal and land the model, adjust the tail trim and try again. Once you are happy with the tail trim keep practising autorotation descents but only down to a height that will give you time to abort (return the hold switch to normal). After hours of practise you will be able to descend at 45 degrees, apply back cyclic to flair (stop the forward speed) and add pitch to land. The difficult part is the timing of all this, if you add to much pitch to early (to high) you will use up the inertia in the rotor head and will not have enough to land. If you add pitch to late the result is obvious.

Autorotations are easier with a 60 size model due to the extra blade power but wither it’s a 60 or 30 size model, the type and weight of the blades will have a major effect on auto performance, use glass/carbon blades like SAB or TG for best performance.

Keep practicing, but remember – it is supposed to be fun!

Level 4 – Setup for Aerobatics

Most transmitters will have three flight modes available via the flight mode switch (sometimes called the idle up switch), this will give you three pitch and throttle curves, one for normal hovering, one for aerobatics like loops and rolls, and the third one can be set for more extreme 3D type flying.

Throttle Curve 1 - Normal

Throttle Curve 1 - Normal

Throrrle Curve 2 - Stunt 1

Throrrle Curve 2 - Stunt 1

Throrrle Curve 3 - Stunt 2

Throrrle Curve 3 - Stunt 2

During aerobatic manoeuvres negative pitch is used during the inverted sections so the throttle curve is set so that it will not drop below 50%, while you have full pitch control. These high throttle curves should only be switched in when flying and not before take off as the engine will over rev in this situation.

Pitch Curve 1 - Normal

Pitch Curve 1 - Normal

Pitch Curve 2 - Stunt 1

Pitch Curve 2 - Stunt 1

Pitch Curve 3 - Stunt 2

Pitch Curve 3 - Stunt 2

The main difference in pitch curves will be in the negative section where up to minus 8% may be used for inverted flight, where as for the hovering mode minus 1 or 2% will be ideal. It is also useful, in the hovering mode, to flatten out the curve at the centre point to make the model less sensitive.

Revolution Mixing

This is available on most transmitters and is quite simply a mixer, which adds pitch to rudder to correct tail swing on adding power. However it is not always easy to set up and if you have one of the latest piezo gyros with heading hold, you probably wont need it.

Cyclic to Throttle Mixing

Some transmitters have dedicated mixers for aileron to throttle and elevator to throttle but you can use any free mixers, try about 20% throttle to start with and if possible only on flight mode 3 for more extreme manoeuvres. Be aware that if your throttle is already flat out, the mix will try to add more throttle and could overdrive the servo, some transmitters (like the JR PCM10) take account of this and therefore will not overdrive the servo.

So your model is now set up for aerobatics!

Rotor Head & Vibration

The main enemy in any model heli is vibration; this can be split into two types; high frequency and low frequency.

High frequency vibration usually stems from the engine, fan or clutch area and cannot easily be seen until cracks appear in the side frames or servos and other radio parts start to fail. All you can do is balance fan and clutch and all should be okay.

Low frequency vibration stems from the rotor head and normally shows as vibration of the tail boom and sometimes on the landing gear. Blade tracking is the first thing to check. Stick a strip of tape to the end of each blade, a different colour each end is required, as you bring the head speed up and looking at one side of the rotor disc you will be able to see if one of the blades is higher than the other (out of track) the different colour tape will tell you which one is high or low so it can be raised or lowered by adjusting the pitch control link.

The blades that came with your heli are probably wooden and will need balancing, how to do this is normally explained in the manual, however, I would try to use quality carbon/glass blades, I know they are more expensive but they do come ready balanced and their performance is far beyond that of wooden blades. I have used SAB, TG and NHP blades and have never had a set out of balance. I have not used any other make so I can’t comment.

Other sources of vibration can be the flybar, paddles and feathering spindle. Damper rubbers should be lubricated with silicone grease when fitting and the flybar must be centered with paddles of equal weight.

If your model has been crashed then the main shaft, feathering spindle and sometimes the tail rotor shaft will probably be bent and must be replaced. The feathering spindle can sometimes be straightened but for how much it costs it’s just not worth it. The main shaft must always be replaced as it could be weakened if straightened.

The rotor head speed on a model heli can vary from 1100 rpm to 2000 rpm at the extremes. Generally speaking the higher head speeds help stability, but things will wear more quickly, on the other hand if your head speed is to low the model will be unstable and sometimes the nose will nod up and down. The manufacturer should be able to tell you the maximum head speed permitted but good quality blades are recommended at higher head speeds. In my experience head speeds tend to vary from club to club as everyone sets up their model to sound like other models in the club, resulting in every member having a similar head speed wither its high or low. I run my Raptor 30 at about 1450 rpm in the hover, 1650 rpm in flight mode one, and 1800 in 3D mode.

So run a head speed no higher than you need to and don’t fly with any vibration and your model should perform well for a many hours.

Scale Helicopters

After several years flying model helis I was getting a little bored with throwing it around the sky at great speed and wanted something different. So scale was the way to go with so many skills required it was bound to be interesting.

There are three main ways into scale helis :

1.Buy a complete kit, which includes all scale parts as well as the mechanics. (i.e.Hirobo Lama or JR Ergo Robinson R22).

2. Buy a pod and boom model, which is also designed for use in scale fuselages (i.e. Vario or Graupner/Heim).

3.Buy a fuselage and fit your chosen heli into it.

Option 1 is the simpler and cheaper one although there will be less choice of models. Option 3 will require a higher degree of design and skill to build. Option 2 is I think the best option as once you have the pod and boom model you can fly it for some time to test and get used to it before putting it into a fuselage also there are plenty of scale fuselages to choose from.

Your choice of subject for scale might be your local police helicopter or a military helicopter or maybe one that you have seen on film, like the Airwolf, or it could be one that you just like the shape of. Whatever you choose remember that a full fuselage will always restrict access to the mechanics where as models like the Robinson R22 or Hughes 300 will be more accessible. This may not be a problem to you, but worth bearing in mind.

Three, four and five blade rotor heads can be fitted for more realism though they are expensive and have different flying characteristics to the standard two blade and flybar.

Also available from Vario are models like the EC 135, which has an enclosed (Fenestron) type tail rotor and the Notar which has no tail rotor but uses vectored air instead.

Flying a scale model is quite challenging and requires a great deal of accuracy to make it look realistic. Smooth hovering, slow climb outs and circuits, and nice 45 degree approaches are all part of scale flying. I prefer a model which flies well and looks realistic in the air rather than one which is accurate in every detail but is not flown due to the pilot being afraid of a possible crash, maybe the pilot lacks the confidence or has spent to long on all that detail!

In-Depth – De Havilland DH-88 Comet

May 7, 2010 2 comments

Hi! Welcome to this new category of this blog. Here, i’ll go in-depth on several interesting models, always looking to focus on the less common ones but surely attractive either from a history, flight characteristics, peculiarity, difficulty, style, appearance or symbolism perspective. In most cases, i’m sure a bit of all of these will apply.

To start it off in a nice way, i’ll talk about one of my all-time favorite aircrafts. Don’t ask me why, but the Comet really stands out from every other plane when i compare it with others. It’s style, unique appearance, flight challenge and twin low engine just adds to the pack!

De Havilland DH-88 Comet
De Havilland DH-88 Comet

Specs

  • Crew – 2
  • Propulsion – 1 piston engine
  • Engine model – de Havilland Gipsy Six R
  • Engine power – 172 kW / 230 H.P.
  • Max speed – 206 kts / 237 mph / 382 km/h
  • Cruise speed – 191 kts / 220 mph / 322 km/h
  • Service ceiling – 19.000 ft / 5.791 m
  • Rate of climb – 1200 ft/min / 366 m/min
  • Range – 2.542 NM / 2.925 mi / 4.708 km
  • Empty weight – 2.840 lbs / 1.288 kg
  • Max takeoff weight – 5.320 lbs / 2.413 kg
  • Wingspan – 44,0 ft / 13,41 m
  • Wing area – 212 sq ft / 19,7 sq m
  • Length – 29,0 ft / 8,84 m
  • Height – 10,0 ft / 3,05 m
  • First flight – 08.09.1934
  • Total production – 5 units

History

The de Havilland DH-88 Comet was a twin-engined British aircraft that won the 1934 MacRobertson Air Race, a challenge for which it was specifically designed. It set many aviation records during the race and afterwards as a pioneer mail plane.

Despite previous British air racing successes, culminating in 1931 in the outright win of the Schneider Trophy, there was no British plane capable of putting up a challenge over the MacPherson course with its long overland stages. The de Havilland company stepped into the breach by offering to produce a limited run of 200 mph (322 km/h) racers if three were ordered by February 1934. The sale price of £5,000 each would by no means cover the development costs. In 1935, de Havilland suggested a high-speed bomber version of the DH-88 to the RAF, but the suggestion was rejected. (De Havilland later developed the de Havilland Mosquito along similar lines as the DH-88 for the high-speed bomber role.)

Three orders were indeed received, and de Havilland set to work. The airframe consisted of a wooden skeleton clad with spruce plywood, with a final fabric covering on the wings. A long streamlined nose held the main fuel tanks, with the low set central two-seat cockpit forming an unbroken line to the tail. The engines were essentially the standard Gipsy Six used on the Express and Dragon Rapide passenger planes, tuned for best performance with a higher compression ratio. The propellers were two-position variable pitch, manually set to fine before takeoff and changed automatically to coarse by a pressure sensor. The main undercarriage retracted upwards and backwards into the engine nacelles. The DH-88 could maintain altitude up to 4,000 ft (1,200 m) on one engine.

De Havillands managed to meet their challenging schedule and testing of the DH-88 began six weeks before the start date of the race. On the day of the race, the three distinctively coloured planes took their places among 17 other entrants ranging from a new Douglas DC-2 airliner to two converted Fairey Fox bombers.

The first of the aircraft to fly was registered G-ACSP, named “Black Magic” and was bought by Jim and Amy Mollison (nee Johnson) who were both independently recognised as world record holders in their own right. This combination started the race as favorite. The “Black Magic” was the first of a great new generation of British aircraft that flew with all three of the now commonplace technical features: retractable undercarriage, variable pitch propellors and flaps.

De Havilland DH-88 Comet "Black Magic"
De Havilland DH-88 Comet “Black Magic”

The three Comets were painted in distinctive colours – the Mollisons’ G-ACSP Black Magic was black and gold; Bernard Rubins’ nameless G-ACSR was green and flown by Owen Cathcart Jones and Ken Waller; while G-ACSS, flown by C.W.A. Scott and Tom Campbell Black, was resplendent in red and white and named Grosvenor House.

G-ACSP "Black Magic", the first of the Comets, flown  by Jim and Amy Mollison
G-ACSP “Black Magic”, the first of the Comets, flown by Jim and Amy Mollison
G-ACSR - the green one - landing in Baghdad on its  way to Australia
G-ACSR – the green one – landing in Baghdad on its way to Australia
G-ACSS "Grosvenor House", winner  of the MacRobertson Trophy
G-ACSS “Grosvenor House”, winner of the MacRobertson Trophy

Grosvenor House

“Grosvenor House” went to Martlesham for RAF trials in 1935 and, painted all white as K5084, was a memorable feature of the 1936 Hendon display. It was subsequently damaged when landing with a full load and disposed of as scrap. F.E.Tasker then acquired it and Essex Aero Ltd rebuilt it at Gravesend with Gypsy Six series II engines driving DH variable pitch airscrews. In pale blue and renamed The Orphan, G-ACSS was flown into fourth place in the 1937 Marseilles-Damascus-Paris race by Flg Off A.F Clouston and George Nelson.

Bearing a third name, “The Burberry”, the aircraft left Croydon on November 14th 1937 piloted by Clouston and Mrs Kirby Green, who succeeded in lowering the out-and-home record to the Cape to 15 days 17 hours. Carrying its final name, Australian Anniversary, it left Gravesend on February 6th 1938, but broke no records after the undercarriage collapsed in Cyprus. The last historic flight by ‘SS was one of its greatest. Flown by Clouston and Victor Ricketts, it took off from Gravesend on March 15th 1938, reached Sydney in 80 hours 56 minutes, crossed the Tasman Sea to Blenheim, New Zealand, in 7½ hours, stopped overnight, then returned to Croydon on March 26th. The 26,450 miles had been covered in 10 days 21 hours 22 minutes to set a record which still stands. The Comet then returned to Gravesend where it remained under tarpaulins until rediscovered in 1951. The DH Technical School then restored it to its original MacRobertson condition for display at the Festival of Britain Exhibition, after which it was preserved by the makers at Leavesden until handed over to the Shuttleworth Trust in 1965.

Flights and Records

On December 20th G-ACSR, suitably renamed Reine Astrid, left Evere, Brussels, piloted by Ken Waller and Maurice Franchomme, to carry the Christmas mail to Leopoldville in the Congo, arriving back on December 28th. It was then sold to the French government as F-ANPY and lowered the Croydon-Le Bourget record to 52 minutes during delivery by Hubert Broad on July 5th 1935. In the course of experimental work for a projected South Atlantic mail service, Jean Mermoz made Paris-Casablanca and Paris-Algiers high-speed proving flights in this machine in the following August and September.

A fourth Comet, registered as F-ANPZ, was built for the French government with a mail compartment in the nose. In their experiments with high-speed aircraft providing a mail service to far-flung colonies, the French also produced the Caudron C641 Typhon, an aeroplane that bore an uncanny resemblance to the Comet.

The Portuguese government had similar mail-carrying ideas, and acquired the Mollisons’ Black Magic for a projected flight from Lisbon to Rio de Janeiro. Renamed Salazar and re-registered as CS-AAJ, it was ferried from Hatfield to Lisbon on February 25th 1935 by Senor Carlos Bleck and Lt Costa Macedo, who covered the 1,010 miles nonstop in six hours five minutes. A return trip was made in the following September, and in 1937 Macedo again brought the aircraft back to Hatfield for overhaul; he made an outstanding return flight to Lisbon in five hours 17 minutes in July of that year. Shortly after being sold to Portugal, the “Black Magic” disappeared for a number of decades until it was found languishing on a portuguese farm and recovered to the UK. After passing through a number of owners, “Black Magic” now resides in a safe and secure environment with her own workshop. G-ACSP “Black Magic” is now in the process of a complete restoration to airworthy condition by the Comet Racer Project Group. Although a number of years away she will one day make her second “maiden” flight from the safety of her new home at Derby Airfield.

The last Comet

A fifth and final Comet named “Boomerang” was built to the order of Cyril Nicholson, who planned a series of attempts on the major long-distance records. Piloted by Tom Campbell Black and J.C.McArthur it made a record Hatfield-Cairo non-stop flight of 2,240 miles in 11 hours 18 minutes on August 8th 1935 during the first stage of an attempt on the Cape record. This was abandoned because of oil trouble, and the machine returned non-stop in 12 hours 15 minutes and established a new out-and-home record to Cairo. Although entered in the round-Britain King’s Cup Race of September 7th 1935, “Boomerang” was a non-starter and left a fortnight later for a second attempt on the Cape record; airscrew trouble over the Sudan on September 22nd compelled the crew to abandon the aircraft by parachute.

Radio Control Scale versions

To spice up your apetite, here’s an amazing 1/4th scale (3.35m wingspan!) radio controlled DH-88 Comet flight video. This awesome scale version can be powered up by two O.S. 160-200 size engines (2 or 4 stroke) for an amazing realism. Enjoy!

[to be continued… check back later]

Apache AH-64A RC Helicopter 1/7 Scale

Amazing scale details and flight accuracy. This Apache AH-64A from IndyHelis.com is unbelievable!

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