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-   -   Amadeus (https://www.rcuniverse.com/forum/electric-pattern-aircraft-385/11618998-amadeus.html)

RodneyFord 06-28-2015 12:01 PM

Amadeus
 
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Time for a new F3a model. Electric this time. Working name is Amadeus. The fuselage will be molded and the wings balsa on foam. I will cover the molding process, which is something not seen here much.

RodneyFord 06-28-2015 12:42 PM

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Here are some dimensions.

RodneyFord 06-28-2015 02:07 PM

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I will go through the process I use to make a composite fuselage. I'm up to about 10 now, the last 2 were 40% IMAC so this one is relatively small:D.
I dimension the drawing at 100mm stations and transfer it to 6mm MDF. The off cut will be the splitter plate, more on that later.

ppljr 06-28-2015 02:33 PM

Nice. Be watching with interest.

RodneyFord 06-28-2015 02:37 PM

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From this point I will use different methods to build the fuselage shape. My first plan was to cut 100mm long cross sections derived from the Solidworks model. However I wasn't entirely happy with the shaping in solidworks so I am going to do the shaping free hand using profile gauges to get symmetry. I did use the CNC foam cutter to do the top view though.

http://www.rcuniverse.com/forum/atta...mentid=2106221http://www.rcuniverse.com/forum/atta...mentid=2106222

RodneyFord 06-28-2015 02:49 PM

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Vacuum bagged the other side on. Am using PU glue as it is fairly fast gap filling and works well in the vacuum bag. I have 2 vacuum pumps. This one is for white foam as is a diaphragm pump and is happy running at reduced pressure (5psi here) so it doesn't collapse the foam. The other pump is an oil filled vane pump for composites in molds and is best run at full vacuum or the oil drains out:(.

RodneyFord 06-28-2015 03:03 PM

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Trimmed of the outline with a hand held hot wire. Powersupply is a transformer on a light dimmer.
Started roughing out the shape with a bread knife.



http://www.rcuniverse.com/forum/atta...mentid=2106229

RodneyFord 06-28-2015 03:09 PM

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The canopy/hatch got cut out of the profile and foam glued to it.

http://www.rcuniverse.com/forum/atta...mentid=2106231

RodneyFord 06-28-2015 03:23 PM

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The fin is built up for accuracy. I use Profilli pro for my airfoil work. The airfoil is SD 8020 with the trailing edge thickened to a blunt 6mm and the root high point moved back to blend into the fuselage. The solidworks model helped to visualise the fit. Once the design was sorted out I printed out the ribs and used a glue stick to attach the printouts to the balsa. Lots of ribs for stiffness. Also made some leading edge templates for accuracy.

http://www.rcuniverse.com/forum/atta...mentid=2106238 http://www.rcuniverse.com/forum/atta...mentid=2106235 http://www.rcuniverse.com/forum/atta...mentid=2106237 http://www.rcuniverse.com/forum/atta...mentid=2106236

RodneyFord 06-28-2015 03:27 PM

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Did some rough sanding. 40 grit in one hand and vacuum cleaner in the other:D. Foam can get messy real fast:(.

RodneyFord 06-28-2015 03:32 PM

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Added the hatch base. This is the zero line to set everything from.

RodneyFord 06-28-2015 03:41 PM

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Used the canopy base to set the nose angle at 1/2 degree. There will be no right thrust as the model will have a contra drive or use throttle to rudder mixing if only one prop.

RodneyFord 06-28-2015 04:08 PM

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Glued on the nose ring. Triangulated it for squareness.

http://www.rcuniverse.com/forum/atta...mentid=2106247

RodneyFord 06-28-2015 04:59 PM

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Gluing the canopy base on.

ppljr 06-28-2015 05:45 PM

What was wrong with the shaping in Solidworks? I have had good success with Rhino 3d.

RodneyFord 06-28-2015 06:18 PM


Originally Posted by ppljr (Post 12062729)
What was wrong with the shaping in Solidworks? I have had good success with Rhino 3d.

Solidworks is great. Use it for the 3D printer. For this kind of flowing curve shaping I think Rhino might be better, you know pulling it around with handles. Especially the nose area which is going to be quite complex. I am pretty comfortable with eyeballing it freehand, I think I will get a better result.
Talking about the 3D printer, I will use it to make some parts. I am thinking of inserts to go into the mold for air exhausts. Spat and leg patterns. Am experimenting with nylon filament with a view to doing the 95mm spinner.

RodneyFord 06-28-2015 07:15 PM

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Did some rough shaping on the lower nose area. Actually nothing complex here, just want it fairly low drag and smooth here to get the air moving down the fuselage easily. Not worried about taking off too much foam as it is easy to build up later with bondo after it gets glassed. Much harder to take glass away and redo it.

http://www.rcuniverse.com/forum/atta...mentid=2106277 http://www.rcuniverse.com/forum/atta...mentid=2106278 http://www.rcuniverse.com/forum/atta...mentid=2106279

RodneyFord 06-28-2015 09:19 PM

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Double sided tape on some thin card to hold the canopy in place for shaping.

RodneyFord 06-29-2015 04:04 PM

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Got some section lines on so I could see the curves more easily and to check symmetry with the profile gauge. http://www.rcuniverse.com/forum/atta...mentid=2106419 http://www.rcuniverse.com/forum/atta...mentid=2106420 http://www.rcuniverse.com/forum/atta...mentid=2106421 http://www.rcuniverse.com/forum/atta...mentid=2106422

brustyrc 06-29-2015 10:17 PM

Very nice work as usual Rob, I'll follow this with interest, 'best, Barrie.

RodneyFord 06-30-2015 12:24 PM


Originally Posted by brustyrc (Post 12063318)
Very nice work as usual Rob, I'll follow this with interest, 'best, Barrie.

Hi Barrie nice to hear from you.
The interesting bits for me are the things that are done differently or in a new way.
These are:
The free form shaping using the profile gauge for symmetry (I got pretty close by eye)

Polyester mold with gel coat sprayed in with popcorn gun (I got a new compressor that will run continuously)

Engineered mold locating and joining system.

1mm Rohacell for the sandwich material in the finished fuselage.

My first decent size electric model. I might do my own contra gearbox, I mean how hard can it be!

drac1 06-30-2015 02:49 PM


Originally Posted by RodneyFord (Post 12063569)
Hi Barrie nice to hear from you.
The interesting bits for me are the things that are done differently or in a new way.
These are:
The free form shaping using the profile gauge for symmetry (I got pretty close by eye)

Polyester mold with gel coat sprayed in with popcorn gun (I got a new compressor that will run continuously)

Engineered mold locating and joining system.

1mm Rohacell for the sandwich material in the finished fuselage.

My first decent size electric model. I might do my own contra gearbox, I mean how hard can it be!

If it were easy, everyone would be doing it. Lol.

Nah, just kidding. Would be well worth having a go. I haven't seen an exploded view of one, but I think there would be a fair bit of work involved. I'm a first class machinist by trade, so would be very interested. Post plenty of photos and give a good description of what you do if you decide to try.

RodneyFord 06-30-2015 03:57 PM


Originally Posted by drac1 (Post 12063623)
If it were easy, everyone would be doing it. Lol.

Nah, just kidding. Would be well worth having a go. I haven't seen an exploded view of one, but I think there would be a fair bit of work involved. I'm a first class machinist by trade, so would be very interested. Post plenty of photos and give a good description of what you do if you decide to try.

The Adverrun looks quite achievable. Need to cut spur gears and make shafts but I am set up for that. The Brenner system is more elegant to my mind but needs a high level of machining.

RodneyFord 06-30-2015 03:58 PM

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Took the canopy off and lined the front and rear.

RodneyFord 06-30-2015 03:59 PM

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An issue with this type of pattern is the lack of rigidity. At the moment it is a bit of a banana by 4 or 5 mm. I will need to stiffen it up or anything could happen when I glass it. I have put the laser line on it here to see how it is. I think I will inset some spruce strips along the sides and hold it straight while the glue dries.

RodneyFord 06-30-2015 03:59 PM

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Faceted the bottom of the fuselage. Going to experiment with a dorsal fin as an add on and this will help integrate it into the rest of the fuselage.

RodneyFord 06-30-2015 04:00 PM

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A more chiseled look to the nose. Will keep working on this.

RodneyFord 06-30-2015 08:28 PM

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Blending in the fin.
http://www.rcuniverse.com/forum/atta...mentid=2106688

serious power 07-02-2015 01:27 AM

Hi Rodney,
Interesting project !!
What density Rohacell are you going to use ??

Brian

RodneyFord 07-02-2015 01:38 PM


Originally Posted by serious power (Post 12064282)
Hi Rodney,
Interesting project !!
What density Rohacell are you going to use ??

Brian

Hi Brian
It is Rohacell 51. A group of us got together and imported a good batch of 800 x 1200 sheets from Clarasonic in Thailand NZ$50 (US$40) a sheet. We got a range of thicknesses 1-3mm in .5mm increments, I am thinking 1mm for this model. Interestingly if you google thermo forming Rohacell there is plenty of info out there. I usually use a heat gun to form the PCV foam we have been using but will try going further and get the Rohacell to form to the full canopy shape.
Rod

RodneyFord 07-02-2015 04:14 PM

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Got the front and rear lining on the canopy. It's spaced from the fuselage a little for something to come and go on.

http://www.rcuniverse.com/forum/atta...mentid=2106963

serious power 07-03-2015 12:25 AM

Hi Rodney,
An idea might be to keep the plug for thermo-forming.
Any reason why you did not go for the 31 ?? A M\2 of 31 at 1.5mm weighs less than a 1mm M\2 of 51. You can use the 1.5mm in the big flat areas for extra stiffness in the section.
We found the 31 plenty strong enough in compression for all our lay-up purposes and out of the sandwich it is way stiffer than the same thickness honeycomb.
I have never used carbon veil in a mold lay up but I am using it instead of glass for finishing.
It might be worth your while to try ; 0.5oz outside and 0.3oz on the inside on a 10cm X 10cm test piece - I pretty sure it would be great.
However glass on Rohacell looks nice.

Brian

RodneyFord 07-03-2015 12:53 PM


Originally Posted by serious power (Post 12064769)
"Hi Rodney,
An idea might be to keep the plug for thermo-forming."

Yes I thought that too. Although I usually do it into the mold. I might need to get some high temp vaccuum film And heat the foam through that.

"Any reason why you did not go for the 31 ?? A M\2 of 31 at 1.5mm weighs less than a 1mm M\2 of 51. You can use the 1.5mm in the big flat areas for extra stiffness in the section.
We found the 31 plenty strong enough in compression for all our lay-up purposes and out of the sandwich it is way stiffer than the same thickness honeycomb."

Actually I never thought about getting the 31. We were mainly interested in doing the 40% IMAC models with composite wings. I think the 51 is for a better surface finish when pulling full vacuum. You are right about the big flat areas, am thinking about a honeycomb ladder down the fuselage.

"I have never used carbon veil in a mold lay up but I am using it instead of glass for finishing.
It might be worth your while to try ; 0.5oz outside and 0.3oz on the inside on a 10cm X 10cm test piece - I pretty sure it would be great."

I will do some test pieces. It would be interesting to see how the carbon veil handles. The CL guys use it on their wings, which might be worth thinking about. I wonder how it would effect the RF. Mind you I'm flying Jeti with dual path so with the telemetry would probably get it sorted out.

"However glass on Rohacell looks nice."

This is plan A however I have enough 1oz Kevlar if I decided to go that way.

Brian

I'm thinking 2 layers of glass on the outside. Either 25gm-50gm or 2x 50 gm and 1 layer of 50 inside. I will do a test with the Kevlar though.
Probably use lacquer as the gel coat for the weight saving over epoxy undercoat.
I had better see if I can find some finished weights to aim for.
Rod

RodneyFord 07-04-2015 08:35 PM

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Made this setup to hold the fuselage straight while I glue in some stiffeners.

http://www.rcuniverse.com/forum/atta...mentid=2107517 http://www.rcuniverse.com/forum/atta...mentid=2107518

RodneyFord 07-05-2015 02:45 PM

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Glued the other stiffener in. The first one was already holding things straight. Here is the laser on a magnetic stand. The laser is also great for marking out rudder cable runs.

http://www.rcuniverse.com/forum/atta...mentid=2107679 http://www.rcuniverse.com/forum/atta...mentid=2107680

RodneyFord 07-05-2015 03:55 PM

Thoughts on a counter rotating drive system.
 
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I like the idea of building my own drive system modeled after the Adverrun design. The concept has been around for a while, here is a diagram from 2000 for an air boat drive.
http://www.rcuniverse.com/forum/atta...mentid=2107710
The Brenner and Adverrun systems seem to be running props around 4000 rpm. This will determine the gear ratio given the motor Kv and the battery voltage. Out runner heli motors look to have the right Kv, light weight and reasonable cost.

Example
Kontronic 650-62 Kv 620 so it will be doing a nominal 22940 rpm on 10 cells. so it will need a ratio of 5.735/1 to run the props at 4000 rpm.
I have been looking at gears and belts to see what is required. It looks like 1mod for the gears and GT3 for the belts. A 14 tooth belt pinion is a good number so that 6 teeth are always in contact with the belt so we get a pulley of 80 teeth. Minimum distance between centers is around 47mm. A 14 tooth 80 tooth 1 mod gear drive is 49mm between centers so they look pretty closely matched.
Here is a quick sketch of the basic dimensions to see if it will fit in. Looks OK.

RodneyFord 07-05-2015 09:19 PM

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I need to fillet the base of the canopy cutout to reduce stress risers. A handy piece of tube and some bondo does the trick.

http://www.rcuniverse.com/forum/atta...mentid=2107742 http://www.rcuniverse.com/forum/atta...mentid=2107743 http://www.rcuniverse.com/forum/atta...mentid=2107744

RodneyFord 07-08-2015 05:55 PM

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Masked to the center line then put 2 layers of 200gm glass on one side. This goes down nicely in one piece so the only join is on the hard center line.
http://www.rcuniverse.com/forum/atta...mentid=2108137 http://www.rcuniverse.com/forum/atta...mentid=2108138 http://www.rcuniverse.com/forum/atta...mentid=2108139

RodneyFord 07-08-2015 06:26 PM

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Here is a technique I use when glassing wings. Before the resin goes off spread micro-balloons over the surface and rub in. Fills a lot of the weave and doesn't need sanding.
http://www.rcuniverse.com/forum/atta...mentid=2108142 http://www.rcuniverse.com/forum/atta...mentid=2108143

RodneyFord 07-08-2015 10:19 PM

More thoughts on a contra-rotating drive
 
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Well it looks like the biggest challenge with this drive is juggling all the variables and sourcing the parts. I now know a lot more about timing pulleys and belts. The design gradually comes together. It looks like a 520 kv motor is necessary. I could rewind a motor as I have built quite a few CD rom motors for indoor and have a winding machine, however not too keen on that as I know the difficulties:D. Looking like I need 1 mod spur gears and 3mm GT2 tooth belt drive with the whole thing made to work with a 80 tooth belt 9mm wide. I'm kind of thinking the rear prop can run at a (slightly) faster speed than the front one.

http://www.rcuniverse.com/forum/atta...mentid=2108153 http://www.rcuniverse.com/forum/atta...mentid=2108154 http://www.rcuniverse.com/forum/atta...mentid=2108155


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