MX Aircraft MXS - Page 4 - RC Groups
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Dec 11, 2008, 08:14 PM
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Graphics Files

If you want to decorate your MXS to look like the one in the pictures here are the files. I am calling this design "Green Flames". I have a new graphics design in the works, as soon as it's done I will post it as well.

- Birger

P.S. Make sure you print without reduction, specially the canopy.
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Dec 12, 2008, 08:52 AM
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bdelepan how did you make all the litening holes when you cut out your depron? Did you have a tool or just use your x-acto?
Dec 12, 2008, 09:15 AM
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Do you plan on making a build guide with pictures?
Dec 12, 2008, 09:27 AM
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Just used my hobby knife. After some practice I found that by lifting the piece of the the cutting board and using a "Sawing" motion (in-out) I was able to get very tight curves. Of course, any straight lines I just used a ruler. Fore smaller holes, like the bolt holes in the firewall I just used a regular drill bit and drove it by hand.
Last edited by bdelapen; Dec 12, 2008 at 09:28 AM. Reason: Addtl Info.
Dec 12, 2008, 09:33 AM
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I'm currently working on a build guide with diagrams and descriptions, it's about 60% done. This one will be posted by mid December if everything works out to plan. I will be starting a second prototype in January and will take copious pictures of that build. This will help me update the detailed build guide with pictures and also put together a "pictures only" build guide for builders that have done may of these and don't want to read all the detailed descriptions.
Dec 12, 2008, 09:36 AM
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Well I am definitely one who likes lots of pictures.
Dec 13, 2008, 06:10 AM
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Blue Tribal Theme

Hi everyone,

I have been working on the graphics for the second prototype (which I will be starting in January after Christmas Vacation). I thought I would share it with everyone in case anyone was interested.


- Birger
Last edited by bdelapen; Dec 13, 2008 at 10:16 PM.
Jan 13, 2009, 10:09 PM
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What is the full potential of the MXS?

Well, it's been a little quiet here over the last few weeks in big part due to my extended Winter break hiatus to the great white north. I was hoping to find some time over the vacations to finish the preliminary draft of the build guide but that was not to happen. I have made some progress however and it is much closer, maybe at 80% now, but it's still not done.

I did get to go flying for the first time in a month last Sunday and got to take the MXS out for a couple of spins. The exciting part however was that I got together with one of the ace pilots at our club and had him give it a try. All I can say is WOW!!! I'm sure that if I practice for another 10 years I would still not have the skills to do what he did.

I guess that the modern day video games really prepare the current generation with the ability to think and react to so many things at the same time; I still have to think whether I'm flying away from or towards me and whether I'm upright or inverted. My education with Pong, Intellivision and Atari where just not enough. But I digress back to the flight report.

After a quick flight to check the CG (moved it farther back than what I usually use) and some minor re-programming of my radio (some changes to the throttle and a little increase in all the endpoints) it was ready to go up for real. Dean really put the plane through it's paces, he threw every 3D maneuver in the book at it and the MXS handled them very well. I was kicking myself for not bringing a video camera (or at least a digital camera) to take some video with but how was I to know he was going to be there then. None the less, I got to enjoy about 6 minutes of pure joy as I watched my creation reach it's full potential !!!

We had two scary moments during the flight due to a couple of radio lock-outs that lasted about a second each; first one throttle, second one rudder. Took it down for a landing after that.

We had a minor incident during the landing however, one of the wheel pants had come loose and when the plane touched down it dug into a rut and rotated the carbon fiber landing gear strut around and broke it (slightly puncturing the wing skin). Fortunately I have a spare set of LG struts and will try to have it replaced before next weekend (business travel schedule permitting). I did learn one very valuable lesson with this accident and that is that the re-designed landing gear mount is definitely strong enough because it held up to the strength necessary to break the carbon fiber strut; so that design makes me happy. I'm simply going to patch over the tear in the wing skin with some packing tape so that fix will be easy. The tough part is going to be to dig out the remnant of the landing gear strut that is still embedded inside the landing gear mount. I need to do this without ruining the slot since the new gear will have to mount in the same slot.

After the flight the battery and the motor came down relatively cool but the ESC was definitely hot. When the throttle lock-out occurred we speculated the ESC had gone into thermal overload protection and we just took it easy for a minute or so allowing it to cool. The second lock-out however leads us to believe that we were not actually exceeding the ESC capacity but instead the BEC capacity in the ESC (which wasn't aided by the high temperatures). Unfortunately I haven't been able to find published figures on the capacity of the BEC so I can't be sure that this theory is correct. Either way, I am going to replace the current 20A ESC with a 25A ESC and hopefully this will get rid of the problem.

The debrief was very positive (besides the ESC discussion); the only recommended change to the design was to increase the height of the fuselage slightly to give the plane better knife edge performance. I'm not sure if that change will make it into the second prototype (which I hope to start next week or the week after) or not, we will see.

As soon as I get the plane ready for flight again I will have to get Dean to come out and fly it again. This time I will make sure to bring my video camera...
Feb 13, 2009, 11:07 AM
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So what is the update on this???
Feb 13, 2009, 12:02 PM
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Hi Coop,

Manual is still only about 70%, life has gotten in the way . I will hopefully get working on it again here soon. The good news however is that I have printed the plans and ordered (and received) the materials for prototype #2. I will be using the build to validate the changes that I have made to the design as well as to get the pictures that are sorely needed to complement the build manual. Plus, all the customer hardware pieces have been cut out and just need some final sanding to be ready for assembly (I chose to do these up front instead of as I went to speed up the final assembly).

If things go well it will all be done within about a month.

I guess I will also be posting progress on the second build here.

- Birger
Feb 20, 2009, 04:03 PM
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Build Guide is Done!!!

Hi Everyone,

After some effort and the postponement of the initiation of the build of prototype #2 I have finally completed the build guide . This build guide will be augmented with many more pictures when I get the second prototype built but for now it has all the information needed to put together an MXS.

I would like to have a couple of people proof-read it and give it the "litmus test" before I post it up on the thread for just anyone to grab. If you are interested in being one of the early recipients just send me a PM and I will e-mail you a copy of the guide. I don't expect anyone that requests it to build the plane but I would appreciate a read through and any recommendations, changes, omissions, errors or suggestions you would like to make (that would be my errors, not yours). Of course, if you do want to build it...

I will also be replacing the current plans with new ones, there are no fundamental changes, just a couple of very minor changes to the plans themselves. These changes are mostly drafting issues and a couple of very minor mods that can easily be retrofitted, so if have started with these plans don't worry, they are still good.

I also had a question as to whether or not there was interest for an addendum that lists the sources for where I got my hardware and components? There are some parts of the plane that are designed around very specific components and you may be interested in where I got them (that's not to say your LHS won't carry them). If there is interest in this I will put this together.

Finally, short kits: I'm not in the business of designing and commercializing model airplanes, I do this as a hobby and for the enjoyment I get out of it. That being said, I know that I have used some very custom parts on this design and some of you may have a hard time getting a hold of all these parts. If there is enough interest I would be willing to put together a few short kits for people interested in building the MXS.

What is a short kit you may ask, well probably different things to different people, but to me it would be everything you need to build the plane with the exception of the Depron foam, the carbon fiber rods/tubes/strips, miscellaneous building material, consumables and tools. In other words, a complete set of hardware, possibly with the exception of control rods and control rod attachments (i.e. E/Z links and E/Z connectors) though if you reeeeeaaaallly want the control rods and attachments I could probably swing it. Most of the short kit would be made up of CNC cut plywood and/or Carbon Fiber components that I would be manufacturing as I have for the prototypes (Sheet E). Of course, before anyone would commit to these short kits I would make a very detailed list of what they would include so that there is no confusion (this list will be very similar to the addendum mentioned above).

OK, so as we say here in the US, here is where the rubber meets the road. I guess I'm about to find out how serious the interest is in this design.


- Birger
Feb 20, 2009, 04:25 PM
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Could you confirm if this is still accurate?

Here are the final specifications:
Wingspan: 37"
Length: 33 3/4"
Wing Area: 332 sqin
AUW: 15.6 oz
Wing Loading: 6.77 oz/sqft
Motor: Hacker A20-20L (~200W)
ESC: Atlas 20A
Battery: TP 3S 1320mAh
Propeller: APC 10X4.7SF
FWIW, if I got one I would definitely want the short kit.

Great design!
Feb 20, 2009, 04:45 PM
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Yes, those specs are still accurate for the first prototype. The one thing that I am having problems with is the BEC in the Atlas 20A ESC, on heavy 3D with heavy throttle the ESC heats up considerably and the BEC has cut out on me twice. Part of this will probably be remedied with the additional cooling that has been designed in to the second prototype but I will be changing the ESC to a 25A one on the second prototype.

I have also flown a few Zippy 1300mAh and 1500mAh batteries in the plane, these are heavier than the TP but the behavior and performance is just as good with the small added weight. Due to the nose heavy configuration of the first prototype these batteries have helped push the CG farther rearward for more 3D flight characteristics. Again, the second prototype has been redesigned to take care of the nose heavy condition and you should now have enough CG adjustability with a lighter battery.

Finally, I will be using different running gear on the second prototype, partly to keep the nose weight down and partly to keep the cost down. Although all other things remain the same I will be using:
  • Hobby City TGY AerodriveXp SK Series 28-26 1350Kv
  • Hobby City TURNIGY Plush 25amp Speed Controller

Of course, until I complete the second prototype I won't know if there are any issues with these but all the calculations point to a successful setup.


- Birger
Feb 20, 2009, 04:47 PM
Registered User
Short kit for me as well
Jun 18, 2009, 09:06 AM
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Hi Birger,

Great design. I have completed the basic fuselage and tail surfaces and am just waiting on my LHS to order some carbon fibre stock so I can make the wing spar and start on the wings.

Can you please explain the wing construction in more detail? How is the LE glued? Is one skin glued perpendicular to the other? Are the ribs attached to the spar and then the pre-glued skins slipped into place? If so, how did you achieve a good glue bond between the skins and the ribs/spar?

Finally, would this landing gear be suitable ?

Like you, my build time is limited to when the family has all been put to bed and before I turn in myself. Nonetheless progress has been steady and it has been an enjoyable build so far.


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