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Old Jan 06, 2008, 12:28 AM
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Mark Miller's Avatar
St. Louis, MO
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Build Log
Isthmus Models Blizzard 3.34 Build

Santa Clause brought my son Brendan a Blizzard for Christmas. We decided to do a build thread as we progress. This is his first build up on a molded TD plane so we will be doing it together so he can learn the methods that it takes.

First a little about the model. It is a fully molded sailplane manufactured in Ukraine. It has been available there for awhile but is just now available here in the States. It has carbon molded wings, carbon capped built up spar with balsa shear webs wrapped with Kevlar. The flaps are bottom hinged and top drives while the ailerons are bottom hinged and bottom driven. Fuselage consists of 3 parts. a Kevlar nose cone, a inner front section which is mostly fiberglass and carbon Kevlar hybrid weave where it plugs into the rear section. The rear section has carbon Kevlar hybrid cloth around the wing saddle area with the rest being Kevlar with a carbon strip running down the sides. The vertical fin and rudder is molded Kevlar/Herex/glass sandwich with a skin hinge on the rudder. Empty weight of the fuselage is 15 ounces including the stabs. Empty weight of the model is 57 ounces. The airfoil is a Selig 7037. I think with it's light weight and this great old school airfoil it will make for a easy handling light wind TD ship for the budget minded flyer. This will be Brendan's first full house plane and I think it fills the bill nicely.

Here are some photos of the model before we started the build.

Mark Miller
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Last edited by Mark Miller; Jan 07, 2008 at 08:43 AM.
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Old Jan 06, 2008, 12:46 AM
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We decided to do things a little differently than we have in the past. The Blizzard shares it's fuselage with our Soprano, Piper and Piper XL models. Our first departure was that we usually mounted the servos on the molded surface on the inner nose section. This time we decided to cut that surface out and use a plywood tray. This will allow us to move all of the radio gear as far forward as possible and still have excellent access to the receiver and have a handy place to place a variometer. We will also be using a larger ballast rube that can be accessed from inside the nose cone.

After cutting the surface out for the we made a ply radio tray. This can be kind of tedious but just keep sanding, cutting and carving to fit. We made a template from the first one so we can make duplicated for the next models we build with this fuselage.

We cut out the holes for the servos and receiver. We use HS225MG servos, a JR 790 receiver and a 5 cell 1400 Mha receiver pack. We also used a switch from MPI that has a built in charge jack. Very handy. Make sure that the tray cut out is placed so that you can insert and remove the battery.

Mount the tray with some 2 hour epoxy with West Systems Micro Fibers to thicken the epoxy and add strength. Set aside and let cure.

Hopefully tomorrow we can get the rudder horn mounted and mount the pushrods. We will be making a change so that the rudder horn is inside the surface of the rudder so that it and the pushrod are not out in the airflow.

Mark
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Last edited by Mark Miller; Jan 06, 2008 at 11:20 AM.
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Old Jan 06, 2008, 04:57 PM
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Today I got things worked out for the internal rudder horn. It was easy to do and seems to work well. I cut down a flap horn that I sell. Same as the Hilaunch one. You can flex the rudder back to open up the hinge area so you can work on it.

I cut a slot in the balsa web that closes the front part of the rudder as far down as I could but high enough to be able to have access. I had to cut a part of the wiper off by the horn so that the clevis would have clearance when at the extreme of it's movement. I then cut a hole in the balsa web that closes off the back on the vertical fin so that the pushrod could go through it.

When epoxying in the horn make sure you put plenty of epoxy inside the fin. I use a 2 hour epoxy that is thickened to toothpaste thickness with West Systems Micro Fibers. Cabosil will also work but Microfibers adds to the strength of the epoxy. The rudder is hollow molded so make sure you get enough in there to make a solid connection.

I also included some photos on how I like to mount a threaded pushrod end onto the carbon pushrods. I am using .070 carbon pushrods in Teflon housings from CST. First I sand the end of the pushrod slightly to give it tooth. I then slightly squash the end of the pushrod slightly so that the carbon splits. This will allow CA to wick up into the pushrod and give a solid glue joint. Make sure to roughen the inside of the threaded coupler with a small round jewelers file and rinse out with acetone or some good cleaning solvent. I put some medium CA on the end of the carbon rod and use it to put some inside the coupler. Keep adding CA so that you have the coupler full and all air bubbles have been expelled. I then crimp the coupler twice for a good mechanical connection. I then put a piece of heat shrink tubing over the joint with a little CA inside and shrink it up. When putting the clevis on the threaded coupler I wick some thin CA in the threads so it does not unscrew. I have never had one of these come apart using this method.

Hopefully we can get the pushrod housings installed tomorrow.

Mark and Brendan
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Last edited by Mark Miller; Jan 08, 2008 at 08:44 AM.
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Old Jan 06, 2008, 10:24 PM
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Glad to see a build thread on this. I sm going to follow the progress.
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Old Jan 07, 2008, 07:53 AM
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Any way to get an electric Blizzard?
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Old Jan 07, 2008, 08:37 AM
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I have electric front ends that fit the Blizzard or any of the models I sell that use the same fuselage.
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Old Jan 07, 2008, 08:47 AM
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How does the weight of the Blizzard compare to the others that use the same fuselage? I couldn't find weights for all of them on the website. Thanks.
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Old Jan 07, 2008, 12:46 PM
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Brendan is doing the pushrod install right now. We will report on that later tonight.

I took some quick weights of the various wings. These may not be absolutely accurate as I did them while still in the foam sleeves so they may be an ounce or so lower.

Blizzard carbon wing 45 oz
Piper wing 31 oz
Piper XL 34 oz

Mark
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Last edited by Mark Miller; Jan 07, 2008 at 04:39 PM.
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Old Jan 07, 2008, 06:15 PM
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Wind Shadow's Avatar
East Coast
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Mark,
Can you post a couple more pics of how that rudder horn is fitting up to the rudder?
The pic---IMG_2284.jpg is a little blurry in detail...I am probably gonna' try this on my PXL build.
Thanks!
Rick..in VA.
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Old Jan 07, 2008, 08:16 PM
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St. Louis, MO
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Rick,

Unfortunately I am past the point of getting a good photo of the slot for the horn. I'll be doing a Soprano here soon and maybe can do that part. Getting a good photo from that small an area is hard. GEtting good light and focus in the right place and all. I'll try and post a replacement photo soon.

Mark
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Old Jan 07, 2008, 08:24 PM
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Brendan put in the pushrods today and it went well. We did something a little different than my usual foam disk bulkheads. We out a wrap of good quality double stick foam tape every 6 inches on the housings. We then put in the pushrod without the housing and threaded the housing on the pushrod from the front. We then let the pushrod assembly touch the side of the fuselage and the stickyness of the double stick tape held it place temporarily. If the routing was not what we wanted we could unstick the housing and reposition it. After we were satisfied we mixed some 10 minute epoxy which in this case was quite thick and put a blob over the tape making sure it was well attached to the side of the fuselage now. Whatever epoxy you use should be the thickness of toothpaste so it does not run all over. I like West Systems Micro Fibers.

The pushrods are free of kinks and run smoothly. There was really not much I could photograph since all of the good stuff was down inside the fuselage and not a place to stick a camera.

Tomorrow we will join the front and rear halves of the fuselage.

Mark Miller
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Last edited by Mark Miller; Jan 08, 2008 at 08:45 AM.
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Old Jan 07, 2008, 09:57 PM
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Quote:
Originally Posted by Mark Miller
We out a wrap of good quality double stick foam tape every 6 inches on the housings. We then put in the pushrod without the housing and threaded the housing on the pushrod from the front. We then let the pushrod assembly touch the side of the fuselage and the stickyness of the double stick tape held it place temporarily. If the routing was not what we wanted we could unstick the housing and reposition it. After we were satisfied we mixed some 10 minute epoxy which in this case was quite thick and put a blob over the tape making sure it was well attached to the side of the fuselage now.



Mark Miller
Any hints as to how to get the glue deep into the fuselage along the housing? Of course, with separate front and rear fuselage portions, maybe its not as hard as a more conventional fuse?
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Old Jan 07, 2008, 10:00 PM
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Minnetonka, MN
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Mark,

I like this approach to fastening the pushrod tubes to the fuse.

I have two questions:
(1) Did you clean and/or rough up the interior sides of the fuse to allow the epoxy used to hold the pushrods to adhere well, or does it stick sufficiently to the fuse interior as received?
(2) Which sides of the fuse do your rudder and elevator pushrods run along? (The stab bellcrank on my Piper XL fuse is noticeably closer to the left fuse side, but that is also the side for the rudder control horn, so I am concerned about possible interference. Since the rudder horn is a couple of inches behind the stab bellcrank, I'll probably try to route the rudder pushrod across to the right side and run the elevator pushrod along the left)

Planning and worrying can take more time than doing . . .

-Ben
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Old Jan 07, 2008, 11:37 PM
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St. Louis, MO
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The only hint I have is not to suffer from OCD. What I did was use a 36" dowel that I had to add part of a second one to do. I used a hand held new style lantern type flashlight that you could set on the table. It has kind of a pistol grip so the light sits up off of the table. I could shine that down the fuselage and see what was happening. I picked up a blob of epoxy and ran the dowel down the fuselage until it was where I wanted to put the blob. Yes it will get in the wrong place and yes it will make kind of a mess but with patience and care it is not to bad. I found that resting the dowel on the side of the fuselage it helped steady it.

I did not clean up the fuselage inside. You just can't get in there to do it. You will be amazed how well the double stick tape holds so I have confidence that the epoxy will have a good bond.

Usually as you can see if you look at the Soprano manual, the rudder pushrod starts on the right side of the fuselage when looking from the pilots view, and crosses over before you get to the elevator bellcrank. With this install it worked out so that the rudder started on the right and did not cross over until after the bellcrank. I was able to fit the pushrod on the opposite the access opening. I cut about 3/8" off of the bellcrank and drilled another hole. There is no interference. I will see if I can get some photos tomorrow. Like I said. This is all inside the fuselage so there is not much you can see from the outside.

Mark
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Old Jan 08, 2008, 11:04 AM
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Oshkosh, WI
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Nice Meathod

Nice technique, Mark. I really like the double-sided tape idea you came up with.

When I did the pushrods in my Soprano I found that wrapping the last 1/3 of the dowel in wax paper gives you good control over the blob of epoxy as you place it right where you want it deep in the fuse.

These build logs are really helpful.

Sean
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