Another Shrike Build - 40" span electric - RC Groups
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Nov 07, 2012, 09:32 AM
AndyKunz's Avatar
Build Log

Another Shrike Build - 40" span electric

This build actually began in June 2011. It's one of those projects that started great, then other things came up. Well, I'm hoping that having a build thread will keep me going at it more until I reach the finish line.

When done, this will be the 5th Shrike I've built (although it started as #3). It was sized to take an E-Flite Habu 32 fan which I still have in the box. The wing panels are almost exactly the same size as the Habu 32's - if you wanted to build a quick one, that would be a neat place to start.

Later on I decided to stick with a prop, as the added expense of new battery packs and a charger for them (I have several 4S chargers, intentionally to limit my model size/cost), it would be better to stick with a conventional power system for now.

Construction began around the nose gear. I made a ply box which included the steering servo and the E-Flite electric retracts. The nose retract box would have been needed for the EDF version. It turned out handy for this one, though probably a bit overkill in both strength and weight.
Last edited by AndyKunz; Nov 07, 2012 at 01:08 PM.
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Nov 07, 2012, 09:42 AM
AndyKunz's Avatar
The next thing was to get started on the wings. The ribs are NACA 0012. On the other Shrikes I used a 15% airfoil, but with the expected higher speed I went with 12% for this one. The holes are for the wing joiners.

The root rib gets a ply doubler between the joiners to keep them from ripping out. There will also be small disks to spread the load on rib 3. That gets added later, but it could have been done now.

Wing assembly is very straightforward. The spars are poplar because it's what I had on hand, the TE and LE are hard balsa. The ailerons are built up, and will be joined to the wing when it is sheeted (it gets fully sheeted). The hardest thing was to make a tapered TE - next time I think I'll laser cut it
Nov 07, 2012, 09:51 AM
AndyKunz's Avatar
While the wing glue was drying I started on the tail components. The horizontals are all made from 3/8" square medium to hard stock. The corners are pinned together with 1/8" dowels after the initial glue dries.

The verticals are built from 3/16" thick and are pinned with toothpicks (5/32" dia).

The fins plug into slots in the elevator, and the slots are angled to 10 degrees to match the Shrike look. You can see I've put some extra stab outside the fins, a difference from the stock Shrike. I did this because I wanted to increase the elevator area to be able to increase the angle of attack during landing. The elevator behind the fuselage is virtually useless because of the blanking, so I planned to extend it to the outside. It would look cooler, too
Nov 07, 2012, 10:03 AM
AndyKunz's Avatar
Back to the wing, now to sheet it. The TE was sheeted first so I could add the ailerons. They will be built onto the lower sheeting. Note that the supports for the retracts aren't in there yet, although they should be. The reason is that I'm designing as I build. That's what happens when you don't want to finish the drawings first!

While that dries, I started sheeting the fins and rudders. Yes, I actually did plan the sizes using the width of the wood as a constraint. That's 1/32" sheet.

The extended stab is sheeted, to side first. This will make it easy for me to cut the slot from beneath so the fins plug straight in. After sheeting the rest of the surface, I had to make hatches for servo access. Because I was planning on an EDF, there wasn't any room in the fuselage to hold the servos. My plan is to mount them inside the stab, both elevator and rudder.
Nov 07, 2012, 10:09 AM
AndyKunz's Avatar
Here you can see the entire wing top side has been sheeted, the landing gear mounts are installed, and the servo access panel immediately behind it is ready. The straw is from McDonalds and is the perfect size to use as a conduit for the wires.

The aileron ribs are 1/8" sheet cut to triangles. These are sanded to match the taper for the wing, and the sheeting at the TE is beveled at the same time to accept the other side's sheeting. The two thick ribs (3/8" sheet) are where the aileron control horns will be mounted., and where the wing will be trimmed back to fit the stab that is right against it.

Finally you can see all the flying surfaces together. The ailerons still need to be cut off the wing panels, and the rudders need to be hinged. The elevators have not been made yet. Somehow in all my building, I forgot to do them! Just plain forgot!
Last edited by AndyKunz; Nov 07, 2012 at 10:16 AM.
Nov 07, 2012, 10:26 AM
AndyKunz's Avatar
Now let me take a little detour.

As I said, my original plan was to build this for the Habu 32 fan. To that end, I actually did some work on the fuselage while I was working on the flying surfaces as described above.

The fan is bolted to two hardwood rails that run much of the fuselage length. They form a sort of keel. To this keep I attached a 1/16" ply that defines the edge of the wing/fuselage interface.

Alignment holes are made in it for the wing joiners and for the straw "conduit."

None of this will be used in my prop-driven model, but I still have the parts in case I ever decide to change or build another set of wings.

The nosewheel assembly would be mounted to this, and the rest of the fuselage made of foam blocks, then sanded to shape and glassed over.
Nov 07, 2012, 10:33 AM
AndyKunz's Avatar
The prop fuselage is the same simple balsa box that we all know and love. This one is sized a bit larger than normal because I wanted room inside for extra goodies. This photo was taken when I had the model together for the first time so that I could set the length of the mains to match the nose.

Because it was originally intended to be an EDF, the nose strut is a bit short. My prop is limited to 9" diameter. Inside those blocks of wood is a Power 25, and one of the higher Kv versions should be perfect for a 9" prop on 4S.

This catches me up to the minute on status. I need to start carving the cowl now so I can post some more photos.

In the last photo in the bottom left corner you can see a box for a Speed 400 Shrike kit. That will hopefully assemble itself this winter too.

Nov 07, 2012, 02:59 PM
AndyKunz's Avatar
Opening up the wheel wells and servo hatch were straightforward. The initial servo hatch cuts were to match the internal sides of the hardwood edges. Next, they were opened up a bit more, just to remove the sheeting. This makes it easy to have a ply plate that fits down flush.

The ply cover it then cut to fit snug, and lightly sanded to make room for the covering that will wrap over the edges later. Holes are located on the plate, then drilled. The plate is put in place and the matching holes in the wing are drilled and then tapped for 2-56 bolts.

This is the same series of steps used to fabricate the plates for the tail. The servos will be mounted to the plate with the arm extending. Removing the hatch will thus give unfettered access to the insides which will hold remote receivers and telemetry gadgetry.
Nov 07, 2012, 03:05 PM
AndyKunz's Avatar
Those wing steps were done while the glue in the cowl corner triangles was drying. This will give a bit more strength to the cowl which is needed while working it, as well as provide a little more meat for trimming and streamlining the shape.

I use the spinner as a centering reference, with a pencil trace to show the position. Taping up the spinner protects it while sanding.

In order to work on it easily it's necessary to glue the cowl on temporarily. I will be carving the cowl and rounding the corners on the rest of the fuselage to blend everything together.

After that we will pop the cowl off and hollow it out more to remove weight. But that's getting ahead of ourselves...
Nov 07, 2012, 04:07 PM
AndyKunz's Avatar
OK, I'm finishing up my vacation with one last photo. A little work with a knife, followed by some real coarse sandpaper and then finer and then the soft sander. Quick work, looks great, feels nice and silky smooth.

Can I inject a plug here for a second? Last year I was given a Craftsman dust collector like this one.

What a difference it makes in my shop! Yes, it's loud, but the belt sander, table saw, and sanding bars no longer coat everything with a patina of dust. It's also helpful by reducing the coughing.

I'm back to work tomorrow, no playing during the day.

Nov 07, 2012, 04:20 PM
Surface, Air & Water Rc Toys..
freechip's Avatar
Nice, I need to start building or atleast continue/finish my B17.
Nov 07, 2012, 04:50 PM
AndyKunz's Avatar
Wait until you see some of the other projects sitting on my bench. My goal for this winter is to clean the bench off by (re-)building the models on it.

Some haven't been touched in a long time. One was started by my father when I was a little kid. You'll enjoy it - it has a slight French connection to it

Nov 08, 2012, 05:03 PM
Mustang Fever
Nice work, Andy

I have an Extreme Flight Outlaw with a 25 size outrunner in it, on 4S, turning a 10x6. It has an unlimited vertical and a top end of about 75 mph. I think if you use a 9x10 or a 9x12, your Shrike will maybe go supersonic.

I'm currently building, with lots of breaks, a Dan Savage F4 (90mm EDF). I keep telling myself I'm going to finish it. I'm going to finish it. I'm not going to buy any more plans for any more airplanes until this is flying. Right. The 10' Martin mars awaits.

Nov 08, 2012, 10:56 PM
AndyKunz's Avatar
Hi Bob,

Electricalc says only about 110-120 depending on motor, but that's under 40A.

I had about 3 hours to play tonight, so I worked on the fuselage hatches.

These hatches were built by creating rails (essentially a frame) that matched the inner edges of the fuselage. Anywhere I didn't want glue to stick them together I used thin cellophane tape to mask the wood. Tape was applied to the fuselage between the side and the rails, around the top edge where the top sheeting would go, and between the sheets that defined the front and rear of each hatch. The frame was inserted and pinned into position. I glued the top sheeting on taking care not to get too much onto the tape, and then pinning the top sheeting to the fuse sides, not the rails. During my sanding time last night the hatches were held in place by friction and by the small amount of glue sticking to the tape. Separating them was easy by just sliding a knife under and gently twisting. They popped right off.

To remove the cowl, I first unbolted the motor so it wouldn't break the cowl as I gently whacked it with my palm to pop it free. Next step was to remove the excess wood from the cowl (I left a generous 3/16").

The nose gear bay was simply cut open. I will be making a separate door for it using similar technique to what was done above. It's much easier to make a new one than try to exactly find the edge of the wood for cutting it out.

After that, I made corner blocks for the front hatch back edge and embedded magnets in them. This will be my battery hatch and needs to open quickly. The rear hatch will be for my rx and electronics, so it won't be opened very often. The front edge is held in by dowel pegs, and the rear by a 4-40 into a small block of wood.

Tomorrow I plan to make the connect points for the cowl.

Nov 09, 2012, 09:34 AM
KOMET 44's Avatar
Nov 09, 2012, 09:38 PM
AndyKunz's Avatar
Thanks, Stefan. Lots of the parts of this plane come from my "scrap" bin.

A little more on the fuselage top hatches before we get back to the nose.

In these photos you can see the magnets in the rear corners of the front hatch, the peg holes in the former, and the hold-down bolt. There's also a photo showing the inside of the hatch lids. They're very simple!

The nose gear door is going to rest on some 1/8" sq balsa. The door outside surface is a compound curve, so we are going to make the hatch flat on the inside with a 1/32" ply liner and then sand the outer 1/8" balsa to match the curves. First I "masked" the door edges so that my sanding bar wouldn't eat into the existing surface, then I removed all the excess balsa.

The cowl will have 2 4-40 bolts holding it on. There are small inlays of 1/32" play to prevent the wood from crushing (they're flush now, but will be sanded smoother later). The two tabs are fastened to the cowl with bolts, then the tabs are epoxied to the firewall. The packing tape serves as a mask to keep epoxy from sticking (it sticks to matte cellophane but not packing tape).

I'm going to be working on the nose gear door mechanics next, getting the door hinged and the servo positioned. The door will be controlled by a sequencer in my DX18.

Nov 10, 2012, 08:34 PM
AndyKunz's Avatar
Ah, the nose door! I love it. Below you can see photos of the door in the open and closed position. The servo is an E-Flite DS-35, and ultra tiny fast servo intended for indoor foamies. I had to change the connector to work with standard equipment (it's set up for an AR6300).

There's also a video of the door and gear working together in that ZIP file. These are driven using the "Basic" pre-defined sequence (second on the list) in the DX18. I adjusted the sequence time down to 3.0 for both directions, and tweaked the door position timing a smidgen. It's really cool being able to use a feature in the transmitter that was a lot of fun to develop.

The door looks a little off. The hinges are only held in place with a little friction. They will be much better after the model is covered and I can align and glue things permanently.

Note when the door is open that there is a rail inside the door for the pushrod to be adjustable in a bunch of different positions. Space those holes as close as you can - mine are spaced 3/32" apart. It makes the setup a lot easier. Also, use a servo horn like the one shown, the T type with 3 holes. Those help. And the little V-bend in the pushrod is to make it adjustable too.

Next step will be wingtips. The glue is already dried, I just have to do some sanding!

Nov 10, 2012, 09:38 PM
Surface, Air & Water Rc Toys..
freechip's Avatar
Not sure what is cooler, the sequencer in action or the Black DX18

Sorry if I missed it but what is the wingspan on this and fuse length?
Last edited by freechip; Nov 10, 2012 at 10:16 PM.
Nov 10, 2012, 10:12 PM
AndyKunz's Avatar
The thread title says 40" but with the wing tips I just finished, it's actually 44". The DX18 is one of the first protos. The length from back of spinner to end of fuselage is 27.5" but the elevators will extend a little further back.

OK, wingtips.

The tips are made by sandwiching some balsa. The center core is a piece of 1/4" balsa (cut to rough shape) with the grain running chordwise. This is because the wood extends behind the wing to end with the aileron TE, and this makes it a little stronger. The top and bottom pieces are 3/16" with the grain running spanwise. This is easier to sand to the airfoil. This sandwich is clamped between two solid blocks and clamped overnight.

I didn't show it, but you can do a good bit of ligthening of the wingtip by removing wood from the 1/4" section before gluing the sandwich together.

The root side is then sanded square then glued to the wing tip. Note how the inner layer can be lined up to serve as a reference later when sanding. The glue again is given plenty of time to cure.

After the glue dries you can do a little carving and then sanding. I use blue masking tape at the root to keep from sanding the whole wing skin down to nothing The paper is coarse and attached to a real long sanding bar. This ensures a good airfoil shape matching the wing cleanly.

Next the tips are rounded with a smaller block not as coarse, then lighter grit, and finally with the flexible sander.

As you sand the airfoil to shape you will notice that the layers provide a good reference to how evenly you sanded.

Last edited by AndyKunz; Nov 10, 2012 at 10:19 PM.
Nov 11, 2012, 12:48 AM
Always trying to learn
mejmea's Avatar
Wow, very impressive! Looks like it will be a lot of fun. The "stealth" Dx18 is very cool - is that where all of the secret firmware tests take place before public release? I'll bet it doesn't even show up on radar.

The dust collector was a great addition for your long term health - make sure you have/get some high quality filtering on the outlet.

From the looks of things in the shop, the work that you do during the day, and the number of threads you keep track of here, sleep must be optional.......!
Nov 11, 2012, 03:03 AM
U.K. or New Zealand
FlyingKiwi22's Avatar
Nov 11, 2012, 09:39 AM
AndyKunz's Avatar
Sometimes I go for long periods without sleep, often 16-18 hours a day A lot of this plane was built while I was on vacation last week, or built a year ago in evenings.

Last edited by AndyKunz; Nov 11, 2012 at 02:16 PM.
Nov 11, 2012, 11:09 AM
Registered User
thechannelmast's Avatar


were did you get the plans from thanks for the help
Nov 11, 2012, 02:16 PM
AndyKunz's Avatar
I made them.

Several years ago I used the CD044 plans from Flying Models to draw the outline of the top view in CAD. I scaled it up to 35" span and designed my own structure within that. This one is a scaled-up version of that with some other changes as well.

Nov 14, 2012, 07:52 PM
WILLIAM M's Avatar

I sure do like that retract set up. I looked at the video. awesome !!!
you sure do some nice work.

Nov 15, 2012, 09:01 AM
AndyKunz's Avatar
Thanks, Bill. You're work isn't too shabby either!

Nov 18, 2012, 04:39 PM
AndyKunz's Avatar
I haven't forgotten this thread, just been a little busy this week.

Today I show the elevators being built. I realized I needed to do this before making the servo mounts for elevator and rudder, but also that I needed to coordinate them some.

The elevator is built in two sides. This is just a style thing, and to get useful surface action for a landing flare with the increased outer area.

The frame is 3/8" sq, same as the stab. The single "rib" near the middle will hold the control horn (I'm using the hardware set from the E-Flite Habu 32). It aligns with the servo arm - you'll see that setup later on.

After the frame was dry, I attached it to one side of the sheeting (pre-cut to shape). These will be beveled to give a taper. Attaching the one side of sheeting now makes them stronger and easier to hold while beveling.

I prefer the built-up control surfaces because they are lighter, stronger, and resist warping.

Nov 18, 2012, 05:08 PM
Always trying to learn
mejmea's Avatar
So will you just taper the side that is not sheeted yet (i.e. asymmetrical taper)? I'm not understanding how you could taper the sheeted side without sanding through the sheeting - unless the taper only takes place over the last 3/8 where the framing is?
Nov 19, 2012, 09:38 AM
AndyKunz's Avatar
I'm going to take advantage of a little geometry by making the taper only on one side.

Right now if you look at the side view it's a rectangle. I'll be removing wood from one side only (the unsheeted side) to turn it into a right triangle. Then I'll sheet the remaining side, still keeping a right triangle.

If you lift up the point so that it's halfway up to the max thickness (ie, "neutral" elevator) then you notice that the bottom (first-sheeted) side now has a little gap. I will remove a little more triangle from the LE so that "down elevator" really is down.

I'll try to remember to photograph each step since you asked. Thanks for asking.

Nov 19, 2012, 12:49 PM
Mustang Fever
Just a note here: I have the templates for all the Shrike 40 parts (ribs, bulkheads, etc) and the build book used in the Lanier BIY kits as PDFs and can send them to whoever would like to build one. (No charge, of course) I haven't had my plans scanned in yet, but could do so anytime and send those as well.

My Shrike is plans built from the info I have. The main thing I did differently from the original kit design was to do away with the 1/4 square spruce wing spars, and use 3/8 carbon fiber tubing instead. Much easier to bore round holes than to cut square ones.

Once you've flown a Shrike, you'll always have to have one. They're in a class all by themselves when it comes to handling and grooving. I think mine is also my fifth- 40 kit, 2- 10 kits, 40 ARF, and this 40 scratch build. Took me a long time to correct all the mistakes I made, the biggest being messing with the CG. I left it right at where it shows on the plans for this one, and that prevented troubles.

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