speedracerntrixie

My Feedback: (29)

I caught the last pattern contest at my local club last year and decided to build a 2X2M Laser for pattern competition in 2011. With all the rain we have been having I have been able to make some decent progress. The fuse is all but done and I spent most of this morning on a motor mount. The gear I ordered is too long so I am going to move the gear mount up a few inches. At this point with everything pictured including two 5S 5000 MAH batteries it weighs 6.8 lbs. Getting concerned about the weight.

speedracerntrixie

My Feedback: (29)

Wow over 200 views and no comments? Don't be shy guys. this is my first pattern build and first big electric, would love some feedback good or bad

Roberto B.

Maybe is because your plane is sooo.. (cough cough).... "unusual" since the actual trend in F3A.
I suggest you to riconsider totally your way of mounting the engine. I think it's a litte under designed for the massive torque of these motors. Try to take advantage of the full width of the firewall.

matt13

Keep posting the build photo's, it was not that long ago when we first went to the two metre rules that there were quite a few stand off scale types getting around.

It may not fly as well as a purpose designed F3A, but if you enjoy it, and it gets through the sequence, well that's what it is all about.

I would have a good look at the mounting as Roberto suggested though, it could undo all of your good work if it is not strong enough.

speedracerntrixie

My Feedback: (29)

Yes it is a bit unusual but my hopes are that it will fly well enough to be competitive up to Advanced class in my region. I do still fly IMAC and wanted a pattern airplane that flies simular. I will investigate the mount a bit more however it is much mose sturdy then the mount the motor came with. My biggest concern right now is the weight.

Ryan Smith

My Feedback: (25)

Are those nylon bolts with nylon standoffs and nylon locknuts for the motor mount?

speedracerntrixie

My Feedback: (29)

yes that is nylon hardware. I am a little surprised about the responses I have been getting about the motor mount. If this were a gasser, I would never have attempted a mount like this but being electric I think it will work without being over built. I work in a composites shop that builds military hardware and the techniques in that mount are utilized inthose productsquite often. All the glue joints are a high grade epoxy with milled fiber added and heat cured at 180 degrees. Themating surfaces were abraded well and cleaned with acetone. I will however be doing some stress testing before the motor spins just to be on the safe side. As just a little side noetpeople have been mounting 150-170cc engines with 1/4X20 stainless hardware for years without problems.


I do appreciate the feedback

rcpattern

My Feedback: (45)

1/4 - 20 stainless and 1/4 - 20 nylon are totally different. The sheer numbers aren't in the same world. I would not use nylon for this purpose, regardless of the size.

Just my .02

Arch

Ryan Smith

My Feedback: (25)

Ask and ye shall receive. The only reason I mounted YSs and Hyde mounts with 6-32 screws was because the mounting holes were too big for 4-40. I don't ever use nylon in any shear application, and that's what you'll be getting with the torque of the motor.

I know I don't doubt the construction integrity of your motor mount, and it's doubtful that others on here do as well. The the professional appearance of the construction of the mount is a testament to your composites background. I just think the thing is too damn complicated. It's neat, appears to be built well, and is definitely outside of the box thinking. However, I think most would agree with me that you would have been better served to extend your motor box sides a couple more inches further forward and bolted the motor directly to the firewall using standard (4-40, 6-32) hardware.

My only other comment regarding the airplane is the batteries appearing to be mounted in the bottom of the airplane. From what I've seen, this is not the optimal arrangement. Primarily for a lazy person, like myself, I don't like flipping my airplanes over. To have to do that every flight stinks. Secondarily, and probably more relevant to the discussion, I've never been crazy about the way pattern planes fly with the batteries so far off of the fuse centerline by being bottom mounted. I've seen several Japanese pattern planes that were retrofitted to electric with batteries in the belly pan, and I did not like the way that any of them presented. The airplanes all appeared to fly with the nose down and did not track straight. My thoughts are that this is a function of vertical CG. The same aiframes that were either glow powered, like they were originally intended, or that were modified to have the batteries sit closer to the fuselage centerline appeared to track much better and the fuselages sat at a better angle in straight and level flight.

This commentary is worth what you paid for it. I am very impressed with your work, as you appear to be a heck of a craftsman. Kudos to you for taking the path less traveled, as well as utilizing a design that has fallen out of favor due solely to its lack of being flavor of the week, on top of adapting that to a 2M airframe.

Good luck with your project, and I for one look forward to seeing its progression.

nonstoprc

My Feedback: (90)

You probably can save some weight by not sheeting the fuse all the way to the tail, to avoid secifically the "tail weight". Some weight can be saved also if the turtle back is constructed by some lighter/thinner wood or foam.

There is a 2m wood pattern construction article on AMA a while back. It is for gas power but should give some idea on how to save weight.

speedracerntrixie

My Feedback: (29)

Ryan, thanks for the feedback, most useful.

I hear you about having to flip the airplane over to install batteries. I was going to make a stand to ease this. The biggest reason I went to the belly was it seemed that I would be able to get the most airflow across the batteries and controller. Obviously I did not consider the vertical CG. It may be difficult to to tell from the pictures but the batteries are actually 4.25" below the wing tube ( Center of battery to center of tube ) it you feel this is too far off the cernter line then I will take your advice and move them to under the canopy and work on getting better airflow to them. I am also going to construct a couple more plates with the nylon hardware and see just what kind of shear force it takes to make it fail. starting over again I would extend the firewall. I originally intended to use an OS 160 . After seeing and talking with a few of the pattern gurus in my district I made the jump to electric.



Nonstop, The fuse is actually quite light. Without the motor mount landing gear it is 1.9 lbs. The fuse is not really sheeted, the 3/32 balsa sides are structural, The fuse is built with these sides as a box if you will with cross bracing to eliminate flex then the formers and stringers are added top and bottom. The turtledeck us 3/16 square spruce stringers with the formers being 1/8 med balsa. I did consider a balsa sheeted foam unit because it would look much nicer but in the end the stringers were chosen because it it lighter.

TonyF

My Feedback: (92)

Vertical CG would have nothing to do with what angle the fuse is in level flight. In fact, lengthwise CG has very little to do with that. The only thing that will control the angle the fuse flies at will be the angle of incidence the wing is mounted on the fuse. But Vertical CG has a lot to do with what the model will do in a vertical upline. Most models that have been originally designed for IC engines need the batteries in the belly in order to have the vertical CG in the designed location. Think about the IC engine cylinder sticking down, then the exhaust system on the bottom. If the packs are located too high, the model will pull to the canopy in an upline, requiring more downthrust.

Ryan Smith

My Feedback: (25)

Where did you mount the batteries for your Partners?

speedracerntrixie

My Feedback: (29)

I suppose the final resting place for the batteries will be determined to where they are located in some of the current F3A airplanes in relationship to the wing tube. The good news is depending on where the batteries sit to get proper CG may allow me to try both locations. I have been flying a 50cc Laser for a little over a year with the engine inverted. Initially on an upline it did tuck to the gear. A tad of up thrust cured that but I do wonder everything else being equal if the CG was closer to the thrustline would it have tucked? Of course airplane trimming is a whole very long topic in it's self.


Tony F Now there is a name that has been around. I remember you first working over at Indy and the first time we met was at an IMS show where you were flying a Heli boy for Walt.

TonyF

My Feedback: (92)

Hi Ryan,

I first mounted them up near the wing tube. The model pulled to the canopy in an upline. I moved them to as low as I could get them, which with the way the gear mounts in a Partner is pretty low, and the pull went away. No other negative things felt when I made the change.

Hi speed,

I never worked in Indy but I did work at World Engines in Cincinnati. I did fly for Walt at a few demos.

speedracerntrixie

My Feedback: (29)

OK Yes now I remember. That was when World was the distributor for OS Max. looks like I will go ahead with strapping them in through the bottom for now. I know it will be inconveinent having to turn the airplane upside down but the cooling will be much better. I am fairly new to electrics but I do know that heat is lost effeciency. Probibly overkill on the 5000 MAH batteries but I would rather end up with some practice packs as opposed to packs that won't get me through the sequence.

I did manage to get everything wired up and did a short 1/2 throttle run up. Scary power is the only thing that comes to mind. And I for years have thought nothing about flipping a 150cc gasser

speedracerntrixie

My Feedback: (29)

I managed to get some work done today. Mounted the wheel pants. They are off a H9 Funtana and are the perfect size. For the 11.00 I paid for them I just couldn't justify laying up my own. As for the cowl and canopy / hatch thats a differnt story. I need to finish up on the canopy plug and get a mold made from it. Then I can make up all the glass parts over a week end. Still have to cut the wings. Does anyone know of a good and easily obtainable material to cut templates from? I have been using 1/8 ply and then rounding the edge followed by a coat of thin CA and finish sand but still having minor issues with the wire dragging.

Ryan Smith

My Feedback: (25)

That's a good looking airplane!

What landing gear is that?

burtona

My Feedback: (50)

Formica kitchen counter top materiel makes excellent templates. The hot wire doesn't melt or burn the edges and the glue side is easily marked with a pencil. Rough cut on a band saw and sand smooth to your outline. You usually can get scraps from a cabinet shop for free.

speedracerntrixie

My Feedback: (29)

Thanks Ryan, the gear was found on Ebay of all places. I'm fairly sure this outfit is subcontracted by many ARF manufacturers. The gears and spinners I ordered from them look identical to the ones that come with the Pilot ARFs.

http://cgi.ebay.com/F3A-100-Carbon-f...item33637d029c



Burtona, I have heard of people using formica, thanks for the reminder. I will give it a try.

Andy P.

A good friend of mine has just received a set of that gear from the same supplier, we compared them to my ZN gear and they are virtually identical in all axis, the only small differences are the weave of the carbon cloth and the thickness of the finished legs. The height, rake and spread are all identical.

nonstoprc

My Feedback: (90)

I used the same gear on my E-converted Sequel. The gear is pretty strong and light in weight. I wish they could provie a set with reduced height measurement.

speedracerntrixie

My Feedback: (29)

Not much new as the holidays are over and it's back to the day job. Out of curiosity I did pull the hatch and cowl off my 50cc Laser and threw them on for a look. The fit wasn't very good but gave me an idea of what to expect.

speedracerntrixie

My Feedback: (29)

A little more progress. The past couple weeks I have managed to move the landing gear to the bottom of the motor box. I think I should have put it there from the start but you know how works in progress can be. I got the tail fairing and cowl layed up and loosly in place. The canopy plug is almost ready to paint and then I will have that mold ready to make a part as well. Gearing up to do the wings next week. Foam and 1/16" balsa sheeting is just sitting in the shop waiting for me.

speedracerntrixie

My Feedback: (29)

Got the canopy plug finished. Next week I will be lay up a mold from it and then by the end of next weekend have a finished glass part. What are you guys using for battery straps and where to get them? I have tried the usual hardware and electronics store and have come out empty handed so far.