Saturday, January 27, 2018

A removable servo tray for thin F3x electro fuselages

Some information about my removable servo tray for the Shinto electro.

It is composed of 2 parts because of the 3D printing constraints. The lower part is just to provide a rounded support to fit perfectly with the fuselage. The upper part allows to mount 2 servos MKS6100/HV6100/HV6110 in a oblique position, upside down, in order to have a free movement of the control rods.

The 2 plate are glued together with some cyano, then fixed into the fuselage with 3 mm screws. On my Shinto, it will be located just in front of the wing joiner. Of course, it means that you abandon the elevator control snakes and sleeves, and replace them with carbon rods and the corresponding MPjet aluminium Threated adapter, so you can easily mount and remove the servo tray when needed.

I will share the CAD drawings and STL files soon.

PS: I like DesignSpark very much !!!!! :)

Thursday, January 25, 2018

A tiny transmitter for foamies ?

Frsky should announce soon a new transmitter, looking like a game controller, but featuring the following:

  • Digital high accuracy hall sensor gimbals
  • Open source operating system - OpenTX
  • Easy access battery
  • Ergonomic design
  • Internal and external antennas
  • Supports external modules
  • Mini USB-B port, Headset port and Micro SD card slot
  • Smart Port
  • 128*64 outdoor readable LCD

Price should be around 100 Euros according to the first webshop displaying it

I guess the target is the Quad racing market, but I was wondering if it would make a good transmitter for my foamies, small enough to carry everywhere, internal antennas so no risk to break it, but still full range.

Of course since my issues with XR receivers, I won't use it for my expensive competition toys.

DesignSpark Mechanical, a great CAD drawing tool !

I wanted to share with you my yesterday finding. Lots of modelers are equiped with 3D printer which are becoming a must-have for us as soon as you are able to design and draw your own parts.
Up to now, as a beginner, I was using Freecad as a CAD drawing tool to produce my STL files. My problem with freecad is that it has bugs and weird behaviour that are often unexplained. This stopped me few days ago while progressing on the Shinto Electro servo tray. Maybe it was the time to find another tool, which I did !!!

There are many cad softwares on the market, some are very expensive, some are online, eventually free, but usually limited. By chance I think I found the prefect software for my need to design, draw parts.

The name of this freeware is "DesignSpark Mechanical" and is kindly offered by RS-online. There are variants for electronic, PCB, electrical, and mechanical design? This is that latest version that I instal. The interface is very nice with smooth operations. The display is very readable in both 3D or 2D sketching. There are few but powerfull tools that allow to sketch complex parts. It can export the file in different format including STL.

Of course, as any software, there is a learning curve, but which can be shortened by watching at the very nicely made tutorial videos. This is allow you to understand better the concept

Overall, my first feeling is that this is a software/interface accessible to everyone and it seems to do the job very nicely and efficiently ... for free !

The following video will give you an overview and a pretty good idea about what is possible and how good and intuitive is this software:

Hope you will enjoy it the same I enjoy it since I discovered it !

Friday, January 19, 2018

Quantum update !

The Quantum n°001 is out of the moulds !!!!! Remain the cut ot the flaps/ailerons. It should land at its new home end of next week :) . Stay tuned !

Sunday, January 14, 2018

Home made tail protection covers

F3X competition planes are sometimes damaged during transportation, especially because we let the V-tail in place.

Tail covers provided with the glider, or bought as an option, a nicely made, but appears to not fully protect from shocks and prints.

I'm now using home made covers using a 2.5 thick foam called "Isolene". This foam has on one face a thin aluminuim sheet.  It costs around 5€ per square meter, given thatt he roll is 1.5m large.

Icut at the shape of the tail with a 1.5cm margin all around the tail.

Then I glue using hot glue, but proceeding 20 to 30 cm at a time, let dry, and continue. Then, with scissors, I cut the excess (around 5mm).

The covers are staying perfectly in place and are never sliding. They also keep the control surface aligned.
The density of the foam is protecting well the surface, and the 1cm excess all around is a good shield against unwanted shocks while manipulating.

I recently found in the same shop a even more dense foam, all white this time, called Isol'choc. Price is a bit more expensive (7€ per square meter). I haven't try yet to glue them, but I think it should worl the same.

Wednesday, January 10, 2018

Quantum F3F

I'm proud and quite happy to say, that finally the Quantum F3F should be alive soon !

It has been a long project since the beginning, project which has nearly died when the initiator and manufacturer just abandonned the design team "in the middle of the river". But after all the effort Dirk Pflug, Gian Marco Occhibove and I put in this project, we just couldn't let it die so we found another manufacturer (ISM), much more serious this time, and resumed the project by revisiting the CAD drawings, doing some changes here and there to help manufacturing, then start milling.

Molds are now finished and the first prototype should be ready beginning of 2018. The time to build it and maiden it, and I will keep you informed and share my first impressions.

The Quantum has been designed only with F3F in mind, starting from an aerodynamic study about optimum turn radius vs plane weight/wind/flight time/Cz/Cx/etc ... 

What has been considered during the design is:

  1. Turn radius versus Wind speed
  2. Turn radius versus plane weight
  3. Turn radius versus initial entry speed
  4. Relative speed/air and Re
  5. Cz in straight line
  6. Cz during the turn
  7. What pourcentage of the time is spent in the turn

From this we could identify and optimize for a certain Cz - Flight Regime, and target the ideal thickness and camber. This allowed us to obtained the necessary requirements to design the section that Dirk then created especially for the Quantum. Wing planform is a pure elliptical lift wing, with a 2.98m winspan and 15.7 aspect ratio. We payed attention to the wing-fuselage and tail-fuselage junctions to reduce the drag with a dedicated root airfoil.

Here are the main data:
  • Wingspan: 2980mm
  • Length: 1465mm
  • Wing area: 55,6 dm²
  • FAI Wing Area: 61,0 dm²
  • Empty Weight: 2,2kg
  • Empty Wing Loading: 39,6 g/dm²
  • Max FAI Flying weight: 4575gr
  • Aspect Ratio: 15,74

The Ballast compartiments in the wings and in the joiner allow to incrementally increase the flying weight up to the max FAI wing loading of 75gr/dm2 without moving the CoG of the plane, so no need to add or remove balance lead in the nose. Also the maximum weight can be achieved without using very expensive tungsten slugs, brass being enough.

I also prepared a simple color scheme proposal that will be available is different color combination (comments are welcome).

You will easily understand that I'm very excited to receive the first prototype and fly it to see how it performs. I'm like a child ... and I have even prepared the 3D printed spacers file to go with the ballast ;)

Ivan Sanda Models will manufacture and sell the Quantum F3F. But please be patient and give us some time to fly the model first and do adjustments if necessary.

F3F season 2018 will be definitively very interresting and challenging for me !

Stay tuned !

Tuesday, January 9, 2018

The perfect F3F slope ?

It is funny to realize that your mind is always polluted by your addiction to slope soaring as soon as you see something that could look like a usable slope :) ...

This week-end, I was in the very south of France (Camargue) where the largest salt production field of Europe is located. Visiting the production fields I could see these nice salt mountains (called "Camel". each of them correspond to a one year of production = average 300 000 tons each), 20m high, more than 100 meters long ;) and exposed to the mistral wind ...
However maybe be too much salty for our material (corosive).

Should I start my detoxification treatment as soon as possible ? :)

A removable servo tray for thin F3x electro fuselages

Some information about my removable servo tray for the Shinto electro. It is composed of 2 parts because of the 3D printing constraints...