Sea Wasp

[jimsp]

Sea Wasp
What do you get when you mix a $23.99 Wasp ARF from Hobby People with a few dollars of foam? You of course get a Sea Wasp.
It’s my latest seaplane which I’m very pleased with. On the water the Sea Wasp is fast, stable and not prone to capsizing. In the air it handles a reasonable amount of wind. The AUW of my Sea Wasp is 25.5oz with a 9.7oz/ft-sq wing loading. I use a Hacker A20- 22L with a 3cell 1500mah lipo but anything in the 100 to150W range should work well.

Here is a brief video. ( http://www.jimsp.rchomepage.com/SeaWasp.wmv) with a few take offs and landings. The wind was shifting a bit and at times I had to deal with a cross wind which is my excuse for the one splash down. It does however; show how forgiving the Sea Wasp can be. As you can see the pond is choked with weeds so I didn’t have the water rudder on. I’m working on the build log and will be putting it up over the next few days

[LukeZ]

Jim this one looks real nice. Can I ask, of all the many variants of these types of flying boats you've designed over the last couple years, which one (or which wing, really) is your favorite thus far? From your videos they all seem to fly well but was just curious if you prefered one to the others.

Keep up the good work,


Luke

[ToxicToast]

Great work, Jim. Love the low aspect of the fuse and wing. The Wasp is indeed a great plane and it looks like it makes a great platform for pond conversion.

Eager to see how much of the original Wasp is under the foam body, so looking forward to your build thread!

Chris.

[jimsp]

Jim this one looks real nice. Can I ask, of all the many variants of these types of flying boats you've designed over the last couple years, which one (or which wing, really) is your favorite thus far? From your videos they all seem to fly well but was just curious if you prefered one to the others.

Keep up the good work,


Luke
That’s a tough question. On a calm summer evening casually flying around the pond with the SS flying boat is an incredibly relaxing experience. Even a large puddle will work.
Because of the ease of flying and simplicity in switching back and forth, the SSFB will almost certainly offer success to one’s first attempt to fly off water.

With the seaplane I like having the ailerons as with the SA Stik and the Wasp. Instead of trying to make them convertible back and forth I like what I did with this one. It’s sort of a generic seaplane. You just use the wing from another airplane which you can move back and forth between the seaplane and original plane. The tail fathers of the original are easy to reproduce and the length between wing and tail can be varied by the length of the basswood boom. I think most wings in this size range should work. With foam wings you mount the pylon over the wing. With build up wings you would mount the pylon ahead of the wing. As you look at the construction I think you’ll see that it would be easy to adapt to other planes.

[jimsp]

Wasp ARF
For those not familiar with the Wasp, here’s a thread ( http://www.rcgroups.com/forums/showthread.php?t=584140)about it. The Wasp has a two piece foam wing that can be built flat with ailerons or with dihedral for 3 channel operation.
It has an 8mm square CF tube for a fuselage. The tail feathers are made from a foamboard type material. It comes with a good quality red tape for covering the wing and tail surfaces. You can use the fuselage and tail pieces to build the Sea Wasp or trace and cut out the tail pieces from a piece of foamboard. Then use a 3/8” sq basswood stick instead of the CF tube. That’s what I did so I would have still have the Wasp to fly in its conventional configuration.

Hull
The Sea Wasp uses the same hull and floats that have proved to be very successful with my Slow Stick Flying Boat (http://www.rcgroups.com/forums/showthread.php?t=359356) and Seaplane. (http://www.rcgroups.com/forums/showthread.php?t=418145)
I do sell the cut foam cores(send PM for details) but I designed the hull so it can be cut by anyone using a scroll or band saw. The cutting doesn’t need to be anywhere near perfect to work very well. The foam used 2’ x 8' x 2” thick EPS foam sheet. This is the white foam sheet insulation found in most home supply stores.

Cutting the Foam
The plans in PDF format are attached. Print out the hull plan and make a template out of poster board. The hull plan is a little longer than 2’ but I still lay them out crosswise letting a little of the tail hang over my 2” wide foam sheet. Cut out 3 of these sections using a scroll or band saw. You could also make templates and cut them with a hot wire. On one of these pieces cut out the battery and radio compartments and the slot for the rear wing saddle as shown on the other plan. Drill 3/16 holes for the float spars on the other two pieces. To taper the sides trace the bottom patterns on the bottom of the hull pieces. Make sure to flip over the pattern so you end up with a left and right side. If you have a tiltable table on your saw, tilt it 10deg and cut the side starting from the rear. Make sure you got it tilted so the top is coming out narrower. My 50yr old scroll saw doesn’t have a tiltable table so I just made a tilted platform with piece of 1/16” ply and ½” thick balsa stick. If you want to cut it with a hot wire there is also a template for the top. Save the halves that you cut off to use as cradles when you are gluing the sections together.

Cut out two floats and the tail pieces the same way you cut out the hull parts. Drill 3/16” holes in the floats as shown on the plans. I like to drill these just short of going all the way though.

[jimsp]

Before gluing the hull together you should make about a ½” hole between the battery and radio compartment. A piece of ½” copper tubing works well for this. Mark the top of the center section where you will cut for the hatch and where to cut to remove the center portion for the radio compartment. Mark the sides in this area and don’t put glue there when gluing on the sides. Note: Do not remove these prior to gluing the sides on.


Glue the sides on using a thin layer of either epoxy or polyurethane glue (Probond Ultimate or Gorilla glue). Put the pieces together and then put them top side down on a flat surface. Adjust the pieces so the back of the step is aligned. Using the cutoff pieces as crutches, lay the hull on its side and add a lot of weight until the glue cures. Make sure to wipe of any excess glue.

Sand the top of the hull so it is flat and sand the rear of the hull to square it up. With the top side down, glue on the first tail piece. When the glue cures, sand the sides and bottom of the tail piece to conform to the rest of the hull. Repeat this with the second tail piece. Cut out the hatch and center section. Save the piece you cut out from the hatch. Epoxy in the 1/16” ply end pieces for the wing saddle. Double check the spacing to make sure the wing fits between them. Epoxy on the ½” x ¼” balsa side pieces. On the outside of each end epoxy on a 4” x 3/16” wing hold down dowel. Epoxy in ½” x1/4” balsa wing supports inside each end. (The ¼” thickness is in the up and down direction)

Glue on a 14.5” long piece of 3/8” sq basswood centered on the rear of the hull starting from the rear wing mount. You may need to notch it to get it under the dowel. If you are using the Wasp CF tube trim the stabilizer mount to remove the part that holds the servos then glue it on to the end of a 14.5” piece of the CF tube. Now epoxy the CF tube on to the hull making sure the stabilizer mount is level with the wing saddle.


I used Dubro micro push rods for the elevator and rudder. The housings go through the wing saddle, along the basswood stick and out the end. Use pins to angle them out slightly toward the end and use a few spots of glue to hold them in place. Check to make sure the push rods move freely.


Use 3/8” slices of foam to fill out the width of the hull on both sides of the basswood or CF tube. (GWS glue works well) If you use the CF tube glue a 1/16” balsa strip along the top of the tube.
Do the same using ½” slices of foam along side the wing saddle. Sand the back of the step to square it up and epoxy on a 1/32” ply strip across the back of it.

Take a ¾ x 1.25” x 3” piece of foam and sand it to whatever shape you like for the windshield. Glue it in place just ahead of the wing saddle.



Now use a sanding block to smooth out mismatches and irregularities in the hull. Also you may want to do some shaping of the bow end. You can round the top edges of the hull but leave the bottom edges sharp. Don’t be too aggressive with the sanding as the foam is soft and it doesn’t need to be perfect like an airfoil. To repair any holes, digs or mismatches lightweight spackling works well.

[jimsp]

Tail
Cover and hinge the elevator and horizontal stabilizer generally as shown in the instruction. The instructions have you leave the edges square and uncovered. I would round the edges and cover them. It looks better and if the paper covering on the foam gets wet it could lift. You could of course use an iron on covering instead of tape. Once the elevator is on, cut a small notch in it at the center at the hinge line. This is to provide clearance for a 1/16 wire joiner on the rudder. Epoxy on the horizontal stabilizer making sure it’s level to the wing saddle and perpendicular to the fuselage. If you are using the basswood stick add 3/8” triangle balsa stock to the bottom rear. Make sure to remove any covering where you will be gluing.

Before covering the rudder, make a groove and drill a hole in the rudder so you can epoxy in the 1/16” wire joiner. This joiner will attach to a ply plate underneath for the rudder horn and a place to attach the water rudder. Cover the fin and rudder. Cut the slots for the hinges but don’t glue them in yet. Glue the fin on and add the 3/8” balsa triangles. Now hinge the rudder to the fin. To provide support for the rudder drill a 1/16” hole in a 3/8” wide piece of 1/16” ply, slip it over the wire joiner and glue it to the basswood or CF tube. The ply tab is made with a piece of 1/16” ply sandwiched between 2 pieces of 1/32”. Mount the horn on this and drill a hole for the screw that will hold on a water rudder.

Hatch
Lightly sand the edges of the foam piece you cut out for the hatch so it will easily fit back into the opening. Cut a piece of 1/32” ply so it hangs over by about ¼” on all sides. Center and glue this to the foam piece. The rear is held down with a 1/8” dowel epoxied into the hatch foam with a matching hole in a piece of 1/16” ply glued onto the hull. The front is held on with a washer glued to the hatch and a magnet glued into the hull.

[jimsp]

Pylon
The pylon is made from a piece of 1/8” ply that is 1 1/4” x 6.5”. This is longer than it needs to be but you will trim it once you are satisfied with the motor position. At one end sandwich it between pieces of ¾” x 1 3/8” ply and ¾” balsa triangle. Cut a notch in the wing support and epoxy in the pylon. The motor stick is made from 10mm wide strips of 1/8” ply. A ¾” long piece is glued between two 2.25” long pieces. To get a tight fit a 1/64” ply shim can be used. The motor stick will be bolted to the pylon at about an 8 degree angle( the motor stick about 3/16 higher at the front of the pylon than at the back..


Covering
The hull and floats should be covered at this point. You can use tape or iron on coverings. Since the surfaces are basically flat the hull and floats are very easy to cover. For more durability I decided to first cover the bottom front of the hull with 3/4oz fiberglass applied using Minwax Polycrylic. This is strictly optional. I’ve made many planes using this hull and this is the first one that I decided to try the fiberglass.

Mounting the Floats
For spars you can use 4mm CF tubes or 3/16” wooden dowels that are about 14” long. On a flat surface assemble the floats, spars and hull. Place a 5/8” high block under the back of the floats. It is likely that the pre-drilled holes aren’t going to lineup exactly so you may have to enlarge the holes to get everything aligned. When you’re satisfied things are aligned, level and equally spaced, epoxy the spars to the center section. After the epoxy cures, glue on the floats.

Wing
Build the wing just as described in the directions. The only change is to notch the front center so the wing will fit over the pylon and wires from the ESC.

[jimsp]

Mount the motor on the motor stick and determine where on the pylon to place it. It should be mounted with about an 8 deg upward thrust(motor stick is about 3/16” higher at the front of the pylon.) and should have about a ½” of clearance for the prop.

Secure the motor stick with 2 machine screws. Once satisfied with the mounting, trim the top of the pylon even with the motor stick.

Test the motor at full throttle. If it appears you are getting excessive vibration add 1/8” balsa on both sides of the pylon to stiffen it.

Paint or put some other protective coating on the pylon as well as other exposed wood parts.

Mount and connect the elevator and rudder servos. I glued on some ply pieces to the foam and then taped or glued the servos to the ply. You could also use servo rails.

I put the ESC inside the hull but you could also mount it alongside the pylon. Although it appears to stay dry inside the hull it’s a good idea to protect the ESC from water just in case there is a problem.

Position the battery to get the CG 3.5” back from the leading edge of the wing. Because the battery is now encased in foam you should check the battery temperature after a few minutes of flying.

If you think you need to add cooling put a hole though from the nose into the battery compartment and an exit hole or holes near the rear of the radio compartment. The hole doesn’t seem to ingest water. I have a cooling hole in my Sea Wasp and even with the splash down shown in the video I didn’t get any water into the battery compartment.

Water Rudder
As long as it’s not too windy the Sea Wasp will turn fine on the water even without a water rudder. If needed, you can make a water rudder out of 1/16” ply and bolt to the ply tab the rudder horn is attached to.

Flying
No special instructions for flying. Just point it into the wind and give it full throttle. You’ll find that the Sea Wasp is very fast on the water. Just a bump of the elevator and you’re airborne. Landing is easy and more forgiving than landing on the ground.

[EP_Soarer]

Thanks a lot Jim, I am hooked! :)
Now I need to find some spare times to build one soon.

However I would try to build a pair of tip floats (at 1/3 span from the tip) instead of using side floats, do you think that could work too?

[jimsp]

Thanks a lot Jim, I am hooked! :)
Now I need to find some spare times to build one soon.

However I would try to build a pair of tip floats (at 1/3 span from the tip) instead of using side floats, do you think that could work too?
The wing tip floats will work fine. I just use the hull mounted floats to make it easy to use any wing.

[Kurpal]

Like the plane, trying to figure out how to build this bird outta blucore. I have so many planes that I want to build this one will have to wait a little while.

[jimsp]

Like the plane, trying to figure out how to build this bird outta blucore. I have so many planes that I want to build this one will have to wait a little while.
The hull for the Sea Wasp is based on my original Slow Stick Flying boat. That one was build using Sturdyboard. I’m sure you could also use Bluecore. The post and link to plans is here. ( http://www.rcgroups.com/forums/showthread.php?t=234990)
For the seaplane you would need to lengthen the fuselage by 2 to 4”. You wouldn’t have to use the WASP wing. Almost any flat bottom wing in the 300 to 400sq. in. range should work.

[warhead_71]

Jim,

Just reviving your thread... I've referenced your design a few times since building my Drake II from BluCor/FFF. The Drake has been used and abused and might not make it through another winter of snow-flying (well over 100 flights), so my sights are set on rebuilding something a bit more durable (5mm thickness FFF hull is fine on water, but takes a beating on hard-packed snow). I thought your SeaWasp looked a bit beefier in that department since it uses a hot-wire cut solid foam block for the fuselage. How's it holding up?

Several things I like about your SeaWasp:

1) Compact height, so it sits lower on the water for great stability and uses less material = less weight and drag.

2) Spruce tail-boom. I nose-dived my Drake when the elevator servo jammed, so the nose was crushed and had to be replaced (cheap and easy), but the impact also caused the tail to buckle... which screwed up the pushrods and stripped the servos (expensive and time-consuming). The tail-boom would give me peace of mind that this wouldn't happen again. Also, I could envision running that boom all the way to the LE of the wing and mounting the motor pod directly to it, using a typical aluminum TowerPro motor mount.

3) Cheap, pre-built wing. Using the cheap Wasp wing is a great time-saver, and worth the money unless you have a couple of evenings to spare cutting ribs and waiting for the Gorilla Glue to set up.

I found another great source for wing cores: Steelhead Products (http://www.steelheadproducts.com/wingcores.htm) has 48" x 8.5" wing halves for $10 a set. They also have 11.5"-chord SlowStick cores, or they can custom-cut any airfoil you want.

Anyway, I think I'm going to incorporate several of your build methods into my next seaplane... sort of a Drake/SeaWasp hybrid.

Thanks for the inspiration.

[jimsp]

The Sea Wasp has held up very well and is probably my favorite of all my seaplanes. The only problem I had with it was when I folded the two piece wing looping into the wind. Fortunately I was able to land it without further damage. I made it a one piece wing and haven’t had a problem with it since.

I had the Sea Wasp at a float fly and was able to easily take off immediately after two fuel powered planes floundered in their take off attempts. Our club always tries to meet and fly on New Years Day. This year it was quite windy but I was able to take off from the snow, fly and land safely.

I think the real success of the plane is due to the basic hull design. I’ve used it successfully on a wide range of sizes and wing types. My latest was on a flat RET foamy called the Nutball. The Video is here (http://www.jimsp.rchomepage.com/Nutfloat.wmv)and the Nutball thread is here. (http://www.rcgroups.com/forums/showthread.php?t=836389) My posts are #1677 and #1684.

For these type hulls I’ve been playing with the idea of first cutting out the internal cavity of the hull in a foam blank and then gluing it between two other blanks. I then cut the hull profile followed by cutting the top to bottom shape. I did this my GWS Sea Cub and it worked fine. The biggest problem is figuring out how to get the control rods in.

The current wing I’m planning to try is the Hobbyzone Super Cub. The wing, tail feathers and decals cost only about $27.