discussion Hi there, my first question

[Guest]

Hi Folks,

I am new to this forum, greeting everyone..

I am basically interested in electric powered scale models, micro size to backyard flyer. My avatar shows one of my models, a 14" span Sperry Messenger.

I wondered if any of you have seen or heard of scale renditions of a Pilatus PC-21. Looks are quite rakish, and it even has built in right thrust. The wings seem a bit short for the fuselage, must be a result of the turboprop on the front.

Do you think this plane would be a good scale subject? The web link is below:

http://www.pilatus-aircraft.com/html/en/products/index_255.asp?NavL1ID=31&NavL2ID=196&NavL3ID=250&NavL4ID=0&NavL5ID=0&NavL6ID=0&L=3

Regards,

Bulent

 

[Guest]

Hi Bulo,

A very warm welcome to the scale models forum. I know you will find a very open and friendly bunch here who are all available to help any one new in any way we can. Feel free to have a look around the numerous resources we have available and enjoy your time with us.

Also feel free to add your own experiences whenever you may find time to add to what we have here to share with everyone else.

As for your model plane I am sure that Wonwinglo will know everything there is to know about it. His knowledge is unbeleivably extensive about all things aircraft and model related.

 

[Guest]

Welcome Bulo, let us see more details of your Sperry , it looks great.

 

[Guest]

Hi,

Thanks for the encouraging words. Here is a photo of the Sperry with the wings removed for transport. It has not flown yet, because it was overweight and I stripped it down to reduce weight - never had time to return to the project. It is RC, has a homebuilt gearbox and a rewound (brushed) motor from a junk CD ROM drive, two Hitec servos which are overkill, a SHR wide band 72 MHz receiver, and two cell 145mAh LiPoly battery.

If this photo goes through and there is interest to see details, I can send other photos.

It looks good because it is heavily painted - one of the reasons for stripping it down. I will cover it with RA microlyte film.

Cheers,

Bulent

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[Guest]

Very nice. I wonder if it isnt overpropped ? One of Gunther props might be better. Paint certainly runs the overall weight up quickly, especially at smaller sizes. 14" is pretty small. Some of the light covering materials come dyed suitable colours, Litespan for example , with some little touches of coloured paint for the engine and tyres you can reduce weight considerably. Tiny vacform pilots are available that add the final touch for hardly any weight. Check the Aeronutz site in UK. Masters of tiny aircraft models. Keep the pictures coming.

 

[John]

I'm overweight but it never stopped me from flying

Welcome to the forum Bulent good to have you here, feel free to post as many pictures as you like, I'm sure there will be a lot of interest, don't forget you can also add them to the gallery

 

[Guest]

Here goes..

Some views of bare parts, and finished results. Tail feathers are actuated by kevlar pull-pull cords and CNC cut horns (0.5 mm PCB material). Servos are HS-50's and are the first parts to replace (5.5 grams each - now we have 1.7 gram servos or 1 gram actuators).

I covered the model with Jap tissue but went quite a bit overboard in spraying it with auto lacquer.

The wheels have o-rings as tire, which could be replaced to gain weight. The langing gear strut is home molded carbon fiber (built a jig for that).

I will send details of the reduction unit and the prop carving jig I built .. The prop may be oversize, it is a balsa replica of a Kavan 6x3 reduced to 5.5" size..

Bulent

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[Guest]

Reduction unit, prop carving jig, nose detail, wing attachment points, carrying case, and cowling attachment method using clothes snaps or whatever they are called..

The speed control is a JMP unit. I carve the jig sides to fit the prop I want to duplicate, and then put in a balsa blank and carve the undersides of the blades - finishing upper surfaces and blade profile by eye..

Reduction unit uses two ball races and an aluminium shaft ( turned using a piston rod scrounged from a Gipsy Major engine - OK I am guilty ); the plate is FR4 printed circuit board material (CNC cut). I added cooling slots to the motor body. The back of the motor has another PCB soldered to the motor body and this acts as the motor mount.

Bulent

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[Guest]

I managed to add photos to the gallery, I will add these there..

Bulent

 

[John]

How do I add these to the gallery?Bulent

Click on the Gallery link in the navbar (blue menu bar at the top) choose upload, browse for the files on your computer add name & comments choose the correct category and press submit

 

[Guest]

Great work Bulo. I like the aeroplane as a subject,but a tad bigger !

 

[Guest]

Hi John,

Thanks, I managed uploading to the gallery, but can I edit picture descriptions, etc. once there ?

I missed your joke on being overweight, sorry. I have almost no extra fat, but unfortunately this does not make my models fly any slower

Regards,

Bulent

 

[Guest]

Hi duncan,

Thanks, I am glad you liked the model. I have also decided to go a larger wing size for my coming projects, as the equipment weight becomes a problem at the smaller wing spans. I made a go at a scratch built Quick Junior, which should build very quickly using depron and come out at 15 grams, but never got to finish it - because I modified it to stick and tissue and also could not get the actuators constructed yet. It has become a Very Slow Junior. I think I am more of a constructor than a flyer..

Dave Robelen and I discussed the wing span issue, and the decision is that 24" wingspan is a good size for micro models.. I am drawing my models for 24" wingspan now.

Regards,

Bulent

 

[wonwinglo]

Bulent,what a great little model,I am sure that you can reduce her weight to get the Sperry Messenger flying,remember auto paint is heavy in pigment and commercial fillers,try watercolours,poster paint,gouche or even pastels ( rubbed into the tissue prior to covering ) onto Jap tissue,ultra light and look good as well.

 

[Guest]

Hi wonwinglo,

Thanks, but I will try thin mylar film (RA microlyte) covering instead of paper/paint, that should save around 15 grams alone. 5.5 gram servos will go, and battery will be one cell. Right now I am working on a sheet balsa version of the Sperry, published as a free plan on the Model Airplane News web site. That should be lighter - around 30 grams:

http://www.modelairplanenews.com/click_trips/april06/sperry_messenger.pdf

What do you think of the Pilatus PC-21 as a scale subject? That issue got lost because of the Sperry Maybe I should start a thread related to that in the Airplane section - I had seen your threads related with good scale subjects..

Regards,

Bulent

 

[Guest]

Hi Bulo

 

[Guest]

Hi Bulo

Ive put a Photo of a Pilatus PC-21 in the planes gallery for you. It was taken at RAF Fairford at the 2002 IAT. hope you like it

Pogo

 

[wonwinglo]

Pilatus PC-21 as a scale subject.

Well lets take a look at this design Bulent and see its potential for scale modelling ? firstly the long nose looks good for electric or rubber power,heavy motors would need to be avoided due to the centre of gravity which could creep too far forward,tailplane is where it should be ie in line with the thrust line giving excellent fore and aft trim,moment arm is fine and would give fine response even with small control inputs,tall fin but not too much to cause weathercocking effect,bi-symetrical wing section would need changing for model use,except a fast IC design,shortish wings would give fast flights even with electric power,washout essential,suggest small inset ailerons,probably best to leave undercarriage off for small handlaunched model,if you do want the gear then build the nose leg to spring rearwards anchoring well into a hardwood block well anchored,watch the weight on this one.

On the debit side you have a large blown canopy, which would weaken the structure if consideration is not given to doublers in that area,a suitable plug would need to be carved from balsa and moulded as per the tutorial instructions.

Summing up,an attractive aeroplane that would need to be built of medium size to get a decent wing area,go for it.

 

[Guest]

Thanks wonwinglo,

The size of the wing ( with respect to the fuselage) is what that gets me worried; it will not be a slow flyer, as you said. The wings could be enlarged, deviating from scale, but this might need modification of the tail, etc..

Not an easy decision.. maybe in the future when I need a fast model.

 

[wonwinglo]

Bulent,I think the wingspan would be fine providing that the model was built large enough,I once built a Tucano that flew like a dream,it was only about twenty inches wingspan.Tailplane area would need enlarging,forgot to mention that.