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View Full Version : Vixen SP400 Pylon racer build thread


Jason T
01-31-2006, 03:28 AM
I decided to build another Matney Models Vixen (http://matneymodels.com/vixen.html) sp400 pylon racer. I had one of these in the past and it was blast. It has a larger wingspan than some of the other sp400 pylon racers and IMHO is a little easier to see. The specs are:
Motor: Speed 400 or Brushless sp400
Battery: 7 or 8 cells
Wing Span: 35"
Wing Area: 132 sq in
Flying Weight: 12 - 16 oz
Length: 21.5 in.

My kit is the bagged wing kit.

I plan to start off by powering it with a brushed motor and will probably upgrade to a brushless later. I can not decide if I am going to run with with a 6v motor and 7 or 8 Nimh cells or with a 7.2v motor and try a 3s lipo pack to keep the weight down. So I am looking for suggestions.

The first pic is the kit contents. It was very well packed for shipping. The wing is well protected because it ships in its foam core skins. The next pic is the included hardware. The torque rods and V-tail linkage is prebent. The next two pics show the fuse which is a translucent red. You can also see that the motor mount is tacked in place. The kit also comes with several sheets showing some dimensions and a CD full of build images and instructions.

Jason T
01-31-2006, 03:39 AM
Here are some build pics. I started with the wing. The bagged wing kit has the skins already on the foam cores and the wing halves are already joined. The leading edge needs to be capped with the included piece of balsa.

The first pic is shows me laying them out. I then mixed up some 30 minute epoxy with microballoons and glued the pieces on. Next I used some rubberbands to hold them in place while they cured. I sanded the leading edges round tonight. It is important to sand the leading edges round not sharp to a point. I will try to get a pic of this later.

Jason T
01-31-2006, 03:54 AM
While the wing was curing I started working on the V-tail. The V-tail comes as one piece that needs to be cut in half down the center. The center was already marked on mine. Before cutting the v-tail in half the instructions say to sand the leading and trailing edges. According to the instructions the tail group edges should be sanded to a sharp edge. It says to mark 1/2" back from the leading edge (parallel with the leading edge) top and bottom. This is the line to sand the leading edge to. Then the instructions say to do the same for the trailing edges top and bottom. The last two pics show the V-tail piece sanded. The first of the two is hard to see that the edges have been sanded but the second one shows it a little better.

Jason T
02-06-2006, 04:05 AM
Got a little more done tonight between super bowl commercials. http://static.rcgroups.com/forums/images/smilies/smile.gif

I glued and sanded the wingtips.

The nest step in the instructions is to glass the center section of the wing with some .5oz cloth about 4" wide top and bottom. I cut two 4" wide pieces of cloth that would cover the center sections of the wing top and bottom then used a finishing resin to apply it. I used an old game room card to squeegee out the excess resin which will minimize the amount of weight added to the wing.

I am letting the resin cure overnight so I went back to the V-tail.

Jason T
02-06-2006, 04:06 AM
I cut the V-tail in half so that I could bevel the edges to 55 degrees so that the assembled V-tail is at 110 degrees per the instructions. I traced out a 110 degree angle on a piece of paper to use for alignment. I sanded each bevel until the V-tail matched the angle. Then I used some medium CA to join the halves. The instructions suggest using a square to ensure that the V-tail is square with the table as well as being at the 110 degree angle.

I plan to install the aileron linkages tomorrow night and if that goes fairly quick I will also install the V-tail linkage.

Jason T
02-07-2006, 03:24 AM
I forgot a step so I did not get to the linkages.

I weighed the wing after the glass cloth was added and it was 2.1oz.

Next, I fit the wing to the fuse making sure everything was square and used 30 minute epoxy to glue the wing cap onto the wing. If I would have had more time I would have probably used 5 minute epoxy and kept working on it.

As a sneak preview I stuck the V-tail under the fuse. I really think the V-tail looks cool on this airframe.

Jason T
02-13-2006, 03:46 AM
This weekend I was able to get the aileron linkages installed and the V-tail linkage installed.

For the aileron linkage I cut small grooves in the bottom of the wing skin up to the fiberglass cloth inside but not through it. I cut a relief groove on the top of the aileron for up deflection and again this only goes down to the glass inside the wing. This groove will be covered with finishing the model. The linkage lays in the groove and is sub flush to the outer skin. Also, the linkage does not need a brass tube for a bearing surface like I orginally thought. The instructions say to coat the linkages with a wax and then when they are epoxied in the epoxy does not cure against the wax leaving the torque rod free to rotate. I used Johnson Paste Wax that I bought at Lowes. With the torque rods lubed up I epoxied them in capping over the top with some scrap pieces of balsa I had laying around. I let this cure overnight and trimmed the caps flush with the bottom wing skin. It took just a little force break the torque rods free then they moved freely.

Next, I cutout the elevators from the V-tail assembly and sanded the leading edges per the instructions so that the bevel was on the bottom side of the leading edge for down deflection. These will be held on with the covering.

To install the V-tail linkage, I cut some grooves in the V-tail similar to the grooves for the aileron torque rods and waxed them before epoxing it in place.

Jason T
02-20-2006, 03:39 AM
Tonight I was installed torque connectors made out of brass tubing that I flattened on one end and drilled a hole for the linkage. I then soldered them to the ends of the torque rods. With this configuration I am using ball joints on the servo side to prevent the linkage from binding. This is overkill but it is much easier to setup.

I also glued the V-tail to the fuse with 30 minute epoxy. The unique thing about the design of the Vixen is that the V-tail mounts to the bottom of the fuse and to me looks very cool. On the bottom of the tail is a slightly recessed area to help align the V-tail. This was the trickest part of the build as you remove the quick link from the V-tail linkage and thread in the push rod. Then I made a Z-bend on the other end and connected to the servo arm. Next, you have to slide the servo with push rod into the fuse so that the quick connector is sticking out of the tail so you can connect the V-tail linkage. At this point I taped the V-tail into place to check fit and squareness. After I felt confident with the positioning I epoxied it on. At this point the servo is loose in the fuse. Before I installed it I checked its center by hooking it up and testing it.

I also starting the covering but only had time to cover the bottom of the wing. I definitely need to brush up on my covering skills. http://static.rcgroups.com/forums/images/smilies/smile.gif Overall it looks pretty good. I cut out the notch behind the aileron for it to be free moving. However, after I did this I am not sure that it was necessary. I deflected the ailerons down to pull the covering over but still went back and cut out the gap covering. I won't do the same on the top of the aileron.

tone
02-20-2006, 08:48 PM
Good build thread Jason,
Hope to see this one at the field before we go to SEFF!

Jason T
02-21-2006, 12:49 AM
Tony, Thanks! Yes, I hope to have it ready soon.

Jason T
02-27-2006, 12:03 AM
Okay. Moving forward, slowly. http://static.rcgroups.com/forums/images/smilies/smile.gif

I decided to change the linkage for the aileron servo so that it would be lower profile when the wing is installed on the fuse to maximize space for the battery. I laid the servo on its side and created the linkages. I am still using the ball joints for now. Then I gooped the servo in place.

I also finished covering the top of wing with a typical high contrast color scheme. http://static.rcgroups.com/forums/images/smilies/smile.gif

All that is left now is to cover the V-tail, glue the elevator servo down in the fuse and install motor and electronics.

Jason T
03-07-2006, 01:05 AM
Okay. I have been on vacation for 4 days but now I am back with a few more pics. http://static.rcgroups.com/forums/images/smilies/smile.gif

One pic below shows the weight of the airframe, spinner, rx, prop, sp400 motor at 9.3 oz. I am waiting on some IB1200 cells and the brushed controller.

The other is the airframe complete waiting on the above parts.

Jason T
03-14-2006, 02:22 AM
Well, I maidened the Vixen last weekend. It was non eventful. I do not have the final power system in it yet because I am waiting on cells for a pack. I maidened it with a 7.2v brushed motor with a TP1320 3s pack. No issues launching. This is definitely not the right power system in my opinion. It seemed to want more voltage. Now, I can't decide if I am going to run a 6v brushed motor or go with a brushless one.

I plan to get video when I get the power system figured out.

HermitRiver
04-08-2006, 06:42 PM
Okay. I have been on vacation for 4 days but now I am back with a few more pics. http://static.rcgroups.com/forums/images/smilies/smile.gif

One pic below shows the weight of the airframe, spinner, rx, prop, sp400 motor at 9.3 oz. I am waiting on some IB1200 cells and the brushed controller.

The other is the airframe complete waiting on the above parts.

Jason. Beautiful job. I like that Vixen, I want one:D Hermit

Jason T
04-08-2006, 09:03 PM
Thanks. :)

They are nice models. I am going to try an 8 cell pack of IB1200's on a 6v brushed motor tomorrow and should be better performance than the 7.2v motor with 3s lipo.

HermitRiver
04-08-2006, 09:10 PM
Thanks. :)

They are nice models. I am going to try an 8 cell pack of IB1200's on a 6v brushed motor tomorrow and should be better performance than the 7.2v motor with 3s lipo.

Jason. Your welcome. Yes they do look like very nice models. I also like the dyed fuses too. I flew electric gliders before lipos and we always had a huge choice of batteries. Nicads and nicads. Good luck with the new combo, be sure to let us know. Hermit

Jason T
04-24-2006, 03:19 AM
Added a decal to the Vixen courtesy of Mike P. Thanks! :) I am going to put another on before SEFF.

jonnyjetprop
04-24-2006, 07:52 PM
Looks sharp:)

John