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Lucas's Rans S-9 Chaos


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This is the build thread for the Rans S-9 as published in RCM&E, but enlarged to 60 inch span (110%). The plane will be modelled after a full size that has been flying on the same airport where I started flying after moving out of the city.

LN-SNI-001-1024.jpg.9f11f379a7b600bad5a81b1aa808ee3c.thumb.jpg.ee07dfe8cc4e8c07ce1cc404cdebfb5b.jpg

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The following has been clipped from the Norwegian Aviation Museums website:Full_DSC_2295-1920x768.thumb.jpg.8d082ac7bc6d6ccfa46ca4e6a01ca5b9.jpg

The aircraft was assembled by electrical engineer and aircraft enthusiast Reidar Berntsen from Tønsberg. After 1,800 hours’ work the plane was ready in 1994. It was approved for use and registered as LN-SNI. Berntsen flew the plane himself and it was a popular feature at aerobatic displays and air shows in South Norway.

 Rans S-9B is a modified version of the standard model Rans S-9. The nose has been extended and the rudder moved further back for better stability. In 2012 Berntsen designed new and shorter wings, specially adapted for airborne docking of free-fallers wearing wingsuits. LN-SN1 is the first and probably only aircraft in the world to be approved for this type of use. The parachutist grabs onto a handle on the wing and hangs there. The extra weight of the parachutist is borne by the jumper's wingsuit, while the aircraft just contributes forward speed.

Because of the changes to the standard model, the Norwegian Civil Aviation Authority wanted ‘B’ added to the type designation of Berntsen’s aircraft, so that the original Rans S-9 became the S-9B we have on display here. After twenty years and 350 flying hours LN-SNI was retired in 2014. For a couple of years, it was displayed at Torp Airport, Sandefjord until Berntsen donated it to the Norwegian Aviation Museum in 2016.

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I will not (yet) be modelling the modifications Berntsen made to LN-SNI, so it will be an S-9 in disguise.

 

HEjUPtq4nkfozoSDjPL6Usatjd0Ghrm_jibUXlRO0oX28hiysJ7v4h8oV0syJqOSliJmje7oWaEIgXi0-DHPeHEI2vORoKYjWUTkJif7je2BOJwS6Su7Rxz25D8QUgwGVnMpScEArBg_SAUotBjBhMBGq3Xe4g1ZzfWtDZqxveNjMBDz3uXasVzUrFS3YIF-Re1WhDmtXE5YFY4AMA-29Fcv88XRVt6LtzMYp2nrXKKDPiYgJMjLfZiwywWzm246R8AprYrqYFNJSWcGB511e4g0mCeg_qH7TphIyOCaiI7U7r390LFLSAeZ43A0XpY9WXlPV9p9R2ReHz33UL5ONwExJ2RNS8nqlnUECyHUKupnrnIucSpTeYFj3yGpr2WK6Ur77TsVNarX28XVIEWz8Q-zFgT5mie2X4lPPH9dV9MiBqRA1fus3fy8Fefpizv4BINEzVO_k8d30EH1TwjsrbECvkkAkDNE8ld5rP6W58IthvBslzDpyXN0v2aEIoZET7Tz_GIPKDvZCGVFOyYc4PBuO2T4J2LkQhREQdyH-MdHNxB-NIkAlk8Eg6JmAqIyQSkjKFOwYF_i2CZNv3MZ-yfVda2Q9In4hTZUng_zYiGjJ1LZjsxV0Nv8o4BgM1ko5Crk9XJJSY4GEYnoH8nqhjs9WXmOSBJjJCm7_Nh5El2Nvh5z4MMD46Jin5bhNqw3h4nLvOaKNiRdtk_dBMq0FPLq--9u2IpBfjs-CYMnkrvTb24NG-R-Nv8iFEfXt9c=w1290-h967-no?authuser=0

 

The first steps were getting the drawings on paper at 110% size. Since I could not get the large plotter to co-operate I hade to print at A3 and patch the tiles together. The printer is not completely accurate, so not everything lines up perfect. but it will have to do.

Next is finding out what is needed, and what of that I have in stock and what has to be bought.  I always create a bill of materials for this. It gives me overview since you need to study the plan well to make one. If anybody wants to do this too feel free to copy the attached document.

For the last scratch builds (Ballerina and Skywriter) I purchased about 50% extra from the Balsa Cabin, and it turned out nearly all wood needed is already in place.

Bill of Materials Rans S-9 110%.docx

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This drawing has only one half of the stabilisor. Since I would like to have the trailing edge continous I need also a drawing of the right half. My printer driver cannot print mirror images, so I used a trick I have read somewhere: wet the paper so that the lines are visible from the back. But I do not remember what fluid to use. I tried polypropanol., since it would not distort the paper.

That works like a charm, but as it evaporates the effects dispappear, so you need to mark enough points you can place all the bits:

image.png.1f0d094838b98ac65ac4ebe67f7dd7cc.png

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Posted (edited)

At last the first bits are in place:

image.thumb.png.31f05a510ce1ef66837b20247bc65947.png

 

I like build up construction. And it is a great way to use the remains of previous builds!

Just so that everybody is warned - I build slow. So sometimes it is more pictures than pieces.....

Cheers, Lucas

Edited by Lucas Hofman
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I'm going to use small screwed eyelets but I've also used fibre glass parts made from 1.5mm sheet.  The rigging wires are the same as the thin fishing trace used for closed loop control. SLEC sell it but I've also bought it from fishing shops.  They're terminated with a loop secured by crimps fastened by squeezing with a pair of side-cutters.

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Yes trace is metal wire.  No turn buckles. Just pull it up till it is firm and then crimp small sections of brass tube on it.

While it needs to be straight to look right it only actually goes into tension as any load is put on it..  

I will photograph mine later this morning.

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20 hours ago, Lucas Hofman said:

Easiest way to cut out all parts is to print them and glue them on the wood needed:

image.thumb.png.ed9ea85265b9ba35afaa71d22f115f0e.png

 

I used 3M's remount spray glue. After the part is cut out one can easely remove the paper. 

Hi, its maybe a little early for my brain to work, but print them from what. Most of us only have the drawing/plan for the model !. The only way would be to get it copied then cut them out etc.Just trying to understand , feel I missed something, not being critical or what ever.

A confused Bas

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Another possible attachment method is to use the eyes of small split cotters epoxied into the mounting point.

 

1 hour ago, Basil said:

Hi, its maybe a little early for my brain to work, but print them from what. Most of us only have the drawing/plan for the model !. The only way would be to get it copied then cut them out etc.Just trying to understand , feel I missed something, not being critical or what ever.

A confused Bas

 

It's even easier if you have a pdf of the drawing.  Most (all?) pdf readers allow you to select a section for printing and they seem to be surprisingly accurate if you select 100% scaling.  I suppose you could select a different % if you wish to scale up or down the model but I haven't tried that

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2 hours ago, Peter Miller said:

I think he means photocopy them or even scan from the plan.

 

A lot of people get the plan copied anyway so they can keep a mint copy while building over the plan.

Peter, I always do that. That way you always have one good copy.

Bas

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7 hours ago, Basil said:

Hi, its maybe a little early for my brain to work, but print them from what. Most of us only have the drawing/plan for the model !. The only way would be to get it copied then cut them out etc.Just trying to understand , feel I missed something, not being critical or what ever.

A confused Bas

Basil, I always start by making a scan to PDF of the drawing. Up to now at the local copy shop, but for the Rans Peter was so kind to mail me the PDF files. 

 

Having those you can - using Acrobat Reader - force display at 100% and pan to the part of the drawing you need. Then you can print it on your own A4 printer. Doing this for everything that needs cutting out gives you the paper templates to glue on the wood.

 

I am lucky to have access to a large plotter so I also can print a copy of the whole drawing to build the wings on.

 

Hope I managed to make myself clear.

Lucas

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Amused myself this afternoon by checking if MotoCalc (the calculator I used to predict motor and model performance) does agree with actual measurements:

 

image.thumb.png.78c9b1684a9eeabb2c320f4fcd436716.png

 

It was way off and predicted much higher current than measured. However, when measuring the internal resistance of the (by now quite old) batteries things became clear. The internal resistance was about 3 times as high as the values I had put in MotoCalc. Those came from the website of the supplier. They may have been accurate though, the batteries are 7 years old and have quite a few cycles on them.

I will use a Turnigy Aerodrive 4240 740kv with a 5S 4000mAh battery driving an APC12x6E propeller. This gives 750W when fully charged, but dropping to 500W at the end of the flight.

Now the battery is know I know if the battery plate needs changing (and thereby the formers it rests on).

 

Cheers, Lucas

ps. Running a motor/propeller at full speed in the workshop give a hell of a noise!

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