Mantis

[rgteel]

I am building a Mantis with the fuse from Terry Luckenbach.
I have never seen the model up close. I am really interested in seeing some detailed pictures of your models and how you attached you wings and tails.
I am also interested in how you constructed your V-tails.
I would like to make the V-tail as a 2 piece.

I have been to the MANTIS WEB PAGE
http://home.att.net/~CASA/Mantis/

Thanks for your time and information!!

Randy

Tulsa, OK

rgteel@cox.net

[Ollie]

I would mount removable V- tail panels to the tail boom with four 1/8 inch diameter carbon rods about 2 or 2-1/2 inches long, two rods for each panel. The trick is to align the pairs rods at the correct angle between the sides of the V-tail and with the wing. To do this you need to make a drill guide for the tail boom. The drill guide consists of four rectangular pieces of 1/8 inch birch ply laminated together. All four have a hole for the diameter of the tail boom near the center and near one long edge. After dry assembling the stack so that the holes are in registration, dress the edges of the rectangles so that they too are in registration. Set aside two of the ply rectangles. Cut 1/8 inch wide slots in the two ply pieces so that the slots are aimed at the center of the circles and angled to the bottom edge of the rectangle as the V- tail will be angled to the horizontal. Flip one of the two slotted ractangles over and place it on top of the other slotted rectangle. The slots will be one behind the other and angled to each other at the V-tail angle. Add the two plain rectangles to the top and bottom of the stack. Glue the stack together in this orientation with the holes and bottom edge in registration. Prepare the tail boom by putting a balsa dam 2-3/4 inches inside the aft end of the tail boom. Pour in enough milled glass reinforced epoxy to make a slug 1/2 inch long aft of the dam. When the first slug of epoxy has cured, place another balsa dam 1/2 inch from the end of the tail boom and pour the cavity full of reinforced epoxy. When the second slug has cured you are ready to drill for the 1/8 inch carbon rods.

To use the drill guide, assemble the wing center section to the fuselage pylon and place the wing upside down on a flat table. Slip the drill guide over the tail boom and position it so that it falls exactly over the first slug. and the long edge of the drill guide is flat on the table. Using the slots in the drill guide, drill two 1/8 inch diameter holes through the tail boom and first slug. Reposition the drill guide to the end of the tail boom and drill two more 1/8 diameter holes through the tail boom and second slug. The first pair of holes witll cross, tangent to each other, inside the tail boom and at the correct V-tail angle and orientation. Also for the second pair of holes. Match the spacing of the holes for the right side panel to the spacing of the holes for the right panel rods when building the rods into the right panel. The rods should stick out of the right panel root a distance equal to the diameter of the tail boom. Do the same thing for the left panel but stagger the location of the rods 1/8 inch so that the leading edges of the left and right panes are in registration. Assemble the V- tail by inserting the rods into their holes and taping the panels in place so that the rods don't slide out of the holes.

You can wrap the outside of the tail boom, about ten turns with kevlar thread fore and aft of each pair of holes to reinforce it against splitting in a hard landing.

[hayman01]

Instead of a v-tail I built a mold for a vertical stabilizer and used Drela's ht14 airfoil for a full flying elevator.
I'll have to look for some pictures.

Bill

[Jack Hyde]

I have a Pretty Mantis (hate that name) fuse with the 130" Aegea wing. I assembled the fuse and trmovable tail the way the brief instructions said to. After about 30 launches, the wing mount pulled out of the pylon at the top of a good launch. The wing fluttered down unscratched. The fuse hit hard dry ground nearly vertical. The nose was damaged, the tail broke but stayed on, and the boom broke just aft of the pylon and just fwd the tail. The rcvr case broke and the crystal was shot but the rcvr works fine with a new crystal. The rest of the damage was not very hard to repair. Its amazing how tough these planes are.

I had assembled the wing mount as the instructions directed but I didn't end up with a structure that did the job. A better job may have worked, but the wing must stay on. After the fix I made 2 steel pins from a 1/8" dia nail each 1/2" long. I drilled 1/8" holes on each side of the pylon near the top and on each side of the mounting bolt and epoxied in the pins. Now if the wing mount wants to leave, it will have to rip out a piece of pylon with it.

I really like the Aegea. It does everything well and lands softer than any plane I have flown.

[Doc Data]

Make sure you guys post some photos of your 'pretty' flyin' boogers! :D

Dave

[hayman01]

I don't care what you guys say. The original Mantis is the prettiest Mantis there is.:cool:

My latest two, Kevlar/Carbon hybrid lay-up's for the pod and pylon and home bagged 130" Aegea wings.

Man O man are they pretty and they fly great.:D

Bill

[emersunn]

I don't care what you guys say. The original Mantis is the prettiest Mantis there is.


Yeah, if the new mantis is the "pretty mantis" does that mean the old mantis is the "ugly mantis"? I don't think so. They are both beautiful ships. Instead of "ugly mantis" it should be "classic mantis"! I prefer the "classic mantis" fuse, and I hope I can still get one in a few years when I get around to building one.

[John Walter]

Ollie:

I like your idea about a removable tail and I might use it on my Manits. My question is, how does one run the pushrods? Outside the fuse like the Bubble Dancer? If so, are the rods on the top or the bottomof the fuse? If on the top, does that cause ballast problems in the wing pylon? If on the bottom, will there still be room for the Rx?

I hope you can help me with your insights. I plan to build my Mantis this winter and a removable tail as you propose sure would simplify transport.

TIA. I hope to see you at Wood Crafters 2004.

John Walter
SOAR Chicago

[Ollie]

John,
If I remember, the tail boom tube of the Mantis is quite sturdy (over built). This makes it a lot less vulnerable to stress concentrations than the BD boom. I think you can safely put a small hole in the top of the boom for the pushrod casings to exit if the hole is minimal and just in front of the forward slug. Be sure to wrap the boom just ahead of the hole with kevlar thread to prevent splitting.

The trick is to keep the teflon pushrods and casings from flopping around in the boom. I would cut a piece of extruded (blue) foam 1/8 inch thick and wide enough to hold the casings to the bottom of the inside of the boom. Wrap the teflon casings to the bottom of the foam strip with kevlar thread, about two turns per inch. Leave about three or four inches of teflon tubing extending beyond the aft end of the foam and end the wrap about 1/2 inch from the aft end of the ramp on the foam strip. The last three inches or so of the foam strip should be tapered to carry the teflon tubes from the bottom to the top of the inside of the boom. The pushrods are loaded into the boom through the hole near the tail. The forward ends of the pushrods where they exit the front of the fuselage tube are inserted into the aft ends of the teflon tubing and the foam strip with the teflon tubes is slid into the fuselage tube. The pushrods are used to guide the aft end of the teflon tubes through the small hole in the fuselage tube in front of the tail. Once the foam strip is in place with about 3 or 4 inches of teflon tubing sticking out at the tail, a few drops of foam compatible CA can be run down the fuselage tube to lock the foam and kevlar wrapped teflon tubes in place. If you use two much CA it can run where you don't want it and cause problems so use it prudently. Depending on the length of the control horns and the placement of the fuselage exit hole relative to the control horns, it may be necessary to build a ramp to support the teflon tubes between the hole and a point about 1/2 inch in front of the control horns to prevent pushrod buckling.

Stainless steel fishing leader about 1/32 inch diameter makes lovely light weight and inexpensive pushrods of the necessary length.

[John Walter]

Ollie:

Thanks for the description. In fact, that is very similar to the approach I used for CF rods in my Majestic.

Now I just need to figure out how to mount the CF rods in the stab!

[Jack Hyde]

I have a Mantis (classic fuse) with removable v-tail that I have been flying a lot for 2 years. The tail was attached to the boom as a fixed tail and flown for a while. Then the carbon boom was cut on either side of the tail to boom joint to remove the tail. I reattached it by simply drilling thru the top of the v and on thru top and bottom of the boom. I used a #6 steel bolt and nut to hold it together. I made a 'seat' on the boom by applying some thickened epoxy to the boom, laid a layer of sandwich wrap on the seat then attached the tail and let it set. After the epoxy cured I removed the tail and peeled off the sandwich wrap.
I used the dowel pushrods that came with the Mantis.

[Jose E Bruzual]

Quote:
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I have never seen the model up close. I am really interested in seeing some detailed pictures of your models and how you attached you wings and tails.
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To attach my wing to the fuse, I made a small platform strong enough to hold the wing in place. It is very important that what ever you do to hold the wing in place is well reinforced; I have seen many wings ripped out of the fuse during launch.

Here is a series of picture showing one way of doing this.


Jose
The ESL
www.flyesl.com

[Jose E Bruzual]

Basic drawings

[Jose E Bruzual]

Made a quick assembly to make sure it fitted

Jose
The ESL
www.flyesl.com

[Jose E Bruzual]

Made some small adjustments once in the fuse

Jose
The ESL
www.flyesl.com

[Jose E Bruzual]

Once assembled with the finished wood.

Jose
The ESL
www.flyesl.com

[Fast-Forward]

Jose....He's the man!

Did someone say pictures.......

[Fast-Forward]

another view

[Fast-Forward]

.

[Fast-Forward]

Tail mounting

[Fast-Forward]

control arm setup

[Jack Hyde]

Jeb,
You said "It is very important that what ever you do to hold the wing in place is well reinforced; I have seen many wings ripped out of the fuse during launch." Very true. Were these Mantises or just planes in general? I have flown about 5000 flights, watched another few 1000 and seen the wings pull out one time, that being on my Luckenbach fuse Mantis. I have 3 classic Mantis fuses that have all hit hard enough to break the boom at one time or another but the wing-to-fuse joint never failed. I am going to beef mine up some more.
I like the Luckenbach fuse and would buy another. The wood parts in the pylon seem to need careful attention.

[John Walter]

Fast-Forward:

I like your removable tail set-up. Could you provide additional details about how you did it? How much weight did it add? It looks like you used blind nuts in the wood inside the fuse. What size of bolts did you use?

Does the added height above the fuse require longer control horns? If so, how does one ensure adequate throw angles? Interesting control horns. Can you provide additional details?

Did you use non-standard pushrods and if so, what type and how did you install them?

Could you post a few more pictures of your removable tail?

TIA.

[Jose E Bruzual]

Originally posted by Jack Hyde
Jeb,
... Were these Mantises or just planes in general?...

This has happened during competition in the ESL with the Terry fuse, now there is NOTHING wrong with the Terry fuse. As a matter of fact I have never seen anything happened to one of terry’s fuse flown by terry himself. Some people have made modification to the Terry fuse; others did not pay particular attention to properly securing the wing mount parts.

Now, for the traditional Matis fuse is virtually impossible for the wing mount to come off due to the building method, that fuselage is virtually indestructible. It takes a lot longer to build than a Terry fuse. I personally like them both and I have both.

One note on those sketches, the bottom plane at 1/8” is too thin, I have double it up and it has the correct structural integrity. One reason I like the plate at the bottom is because it gives me more anchor points so the stress is distributed through-out the bottom and all the parts going to the top of the pod. If you put all your faith in a small block of wood near the top, then it all depends in how well you bond the block to the pod.

-J

P.S. Bill H. is making some nice stuff those pictures he posted, don’t do any justice

[Jose E Bruzual]

Originally posted by jawalter
Fast-Forward:

I like your removable tail set-up. Could you provide additional details about how you did it?

TIA.


Those pictures “Fast-Forward” posted for the wing mount are based on what Terry L. recommends. Here is the diagram included with Terry’s fuse which was used to build the tail you see in the pictures above.

For the Terry fuse and V-tail the method is pretty much a standard and he has been proven in many contests here on the East Coast, the weight and configuration as virtually no negative impact on performance.

We use carbon push rods made by CST and just fallow the instructions for installation. https://www.cstsales.com/home.htm

Jose
The ESL
www.flyesl.com

P.S. If you would like to see more pictures of the tail above you can go to this link, the plane belongs to John Nilsson from the CRRC.

http://www.charlesriverrcpictures.org/09_14_03.html

[Jose E Bruzual]

Rear view of Terry fuse boom

[markdrela]

Originally posted by Jack Hyde
Jeb,
You said "It is very important that what ever you do to hold the wing in place is well reinforced; I have seen many wings ripped out of the fuse during launch." Very true. Were these Mantises or just planes in general?

The usual cause of the wing mounts ripping out is a faulty mount installation. It's important that there is no air gap between the wooden mount and the bottom of the wing.

If there is a gap, the glue joint between the wood and the pylon then gets stressed by the full tension of the bolt, which is huge if the bolt is tightened well. If this joint cracks during tightening, it may not be apparent until the next hard winch launch.

The gap can be easily filled with scrap wood and/or microballoons. Cover the wing bottom with polyethelene, and squish it down onto the filler.

[Jack Hyde]

Mark,
I believe what you describe is how my wing mount failed. I will make an epoxy/ballon bed to fill the gap before I fly again.

[fprintf]

At the contest I was at yesterday there was a mantis. I won't make any comments on its looks, but the talk around the winch as it dorked into the soft turf was that the instructions that come with the plane describe the best landings as those being with a dork type landing. On several occasions the nose of the plane was an inch or more into the turf with the tail surfaces sticking way into the air. Kind of funny to watch!

[rgteel]

Thanks for all of the information on the Mantis!
I am in the process of building the spar. I should
have it ready to install by the end of the week.
Any advice?

[targetdrone]

Originally posted by jawalter
Ollie:

Thanks for the description. In fact, that is very similar to the approach I used for CF rods in my Majestic.

Now I just need to figure out how to mount the CF rods in the stab!

On my first Majestic, I blew the stabs off after trying to save weight by not using spars to mount the stabs to the boom. The boom delaminated where the epoxy held the stabs on.

To fix this, I used CF rods where the aluminum tubing would normally be. I plugged the end of the boom with balsa (use it like a hole saw to fill the boom where the rods go through). The front spar on one stab goes all the way through and out the other side of the boom and the back spar on the other stab goes through. The other CF piece butts up against the rod going through. Sort of like opposing y's. I eliminated the ply pieces normally glued to the boom, and sanded the ply stab root ribs to a concave shape to mate to the boom before epoxying them in place.

This saved almost an ounce and a half in the tail. While my stabs are not removeable, my Eraser and Organic that have removeable stabs always stay together. The fuses stack nicely for traveling. (I have since sold the Organic.) Save all the weight in the tail you can on the Majestic, as you also save 3 times that in nose weight. Mine weighs less than 57oz all up.

My next Majestic will have a carbon boom, a full-flying stab and regular rudder instead of V-tails, and a fair amount of CF in the wing, along with a 3/8 titanium wing rod. I am shooting for under 50oz on that one.

Wiggle your sticks
David Judson