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Jun 24, 2011, 02:46 AM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Build Log

How to build a Swiss Fish

What the Ultralight Le Fish is all about:

(6 min 57 sec)

(4 min 32 sec)

(3 min 37 sec)


Open Source Le Fish Plans & GMFC Cutting Files

The Le Fish glider design has always been and will always be open source.

Plans are released under the Creative Commons Attribution-ShareAlike license which allows personal or commercial use so long as certain conditions are met (details on the plans download page here).

Plans can be download via this link:
In addition, there are CNC cutting files in the GMFC format available via the link above.

Please see the Le Fishipedia for the most up-to-date, consolidated info on building Le Fish.

General Build Tips:

I've arrived at a hardware solution for the ultralight Le Fish build that I'm pretty happy with as far as a general recommendation, especially for first-time Le Fish builders and/or people who don't have a lot of scratchbuilding experience.

Now, first things first: there are many, many, many ways to build a Le Fish and I'm by no means claiming this is the be-all, end-all approach that someone should follow. With that said, it's what I'm currently using, and it's proven to be durable, lightweight, and easy to install - all things that are very important for a "general consumption" type of solution.

Specialists will have their own preferences and very good reasons for same, and may feel their solutions are superior to what I'm putting forward here. They probably are, for all I know! However, I'm just trying to establish a super-easy-to-approach ground floor solution that will result in a plane with good performance, great durability and easy construction - all things I prefer when given the choice

One more disclaimer: I provide manufacturers, suppliers, and part numbers below for your convenience only. I do not have any sort of relationship with any of the suppliers mentioned, do not receive compensation from them, or otherwise. There are many places to find this stuff, I'm just trying to help establish a "known good" baseline. Feel free to substitute for equivalents based on preference, local availability, phase of the moon or whatever. IDGAF, it's your plane after all

So, with those disclaimers out of the way, here is what I'm recommending in terms of hardware for an ultralight (17-20oz / 480-560g) build of Le Fish:

  • 1.3lb EPP for wings
  • 1.9lb EPP for fuselage
  • 6mm sheet Depron or EPP used for ailerons and tail surfaces (full-length cores with ailerons cut off and hinged should work well too, but I haven't tried this on Le Fish yet - though I intend to!)
  • 1.7mil laminating film covering on entire plane, with 3mil on D-Box of wing
  • D-Box = beginning on top of the wing, wrapped from spar forward around leading edge, and back to spar on bottom
  • The film used is the Premium CP Laminating Film from Laminator Warehouse
  • Available in 500' rolls from Laminator Warehouse, or in smaller quantities from Canuck Engineering and Aloft Hobbies (amongst others).
  • Depending on the width used, about 10' - 15' of 1.7mil laminating film, and about 5' of 3mil laminating film will be enough to finish a Le Fish as well as have leftovers for repairs.
  • 0.032" x 0.310" x 72" (7.9mm x 0.8mm) carbon fiber ribbon spar in main wing where indicated on plan, with identical ribbon spar laminated to the subtrailing edge ( Graphlite Carbon Fiber Rectangle Part Number T733L6)
  • No longeron in fuselage required
  • Lightening holes in wings, fuselage, tail surfaces, etc. to taste (they don't save much weight, but they do look very cool!)
  • Hitec HS-65MG or equivalent servos recommended throughout. Metal gears are a good choice for durability.
  • 6V AAA NiMH Eneloop battery pack, or ~700mAh 6.6V LiFe
  • If using LiFe pack, confirm servos & receiver support the higher 6.6V voltage
  • Lithium Polymer (Lipo) chemistry NOT RECOMMENDED for Le Fish!
  • Parkflyer-sized receiver
  • 12" servo extension for elevator servo in tailboom
  • Should take little to no noseweight to balance
  • Reinforce all control horn mounting points top & bottom with sheets of 1/32" plywood or fiberglass / carbon fiber equivalent. This really makes a huge difference in how positive the surfaces feel in flight, and how well they hold up to abuse.

Madslide-style all moving stabilizer hardware:
  • Elevator servo mounted in tailboom just aft of the wing trailing edge
  • 0.125" / 3.2mm carbon fiber tube for stabilizer spar / joiner ( Part Number T512)
  • K & S Tubing 5/32" (3.9mm) x 0.014" (0.35mm) wall aluminum or brass tubing for pivot bearing - perfect sleeve with above CF tube
  • Du-Bro #846 Micro Pull-Pull System with tailboom-mounted elevator servo is an easy and effective off-the-shelf solution that works, but there are other solutions for the intrepid scratchbuilder
  • To get maximum stabilizer travel on high rates, use the furthest out holes on the longest double-sided arm possible for your servo. Use the holes closest to the elevator surface on the control horn(s).
  • If using Hitec HS-65MG for the elevator servo, replace stock servo arms with Du-Bro #934 Micro Servo Arm XL for Hitec or equivalent
  • Setup a low rate with reduced throws for normal flying, as well as a high rate with full throw and maximum exponential (make sure the expo you use softens the feel around center!)

Servos mounted similar to the Aeromod Coquillaj, in fuselage directly in front of wing, offset slightly below the wing centerline.
  • Two options for light, durable pushrods that are easy to build:
  • Option 1: 0.070" (1.8mm) solid carbon fiber rod (CSTSales Part Number T320) glued with medium CA or epoxy to a Du-Bro Mini Nylon Clevis #227 at the aileron surface, and connected to Du-Bro EZ-Connector #121 at aileron servo arm.
  • Can sleeve over this with additional 0.125" (3.2mm) carbon fiber tube as used for the Madstab elevator pivot for additional stiffness at small weight penalty.
  • Option 2: 0.079" (2mm) solid high modulus carbon fiber rod (CSTSales Part Number THM321) glued at both ends with medium CA or epoxy to a Du-Bro 2mm Threaded Coupler #695 with a Du-Bro Mini Nylon Clevis #227

  • Mount servo in canopy area between wing leading edge and battery pack.
  • Du-Bro 30" Micro Pushrod #852 is a durable, lightweight and simple solution - run down the middle of the fuselage between the two halves, exiting approximately 2-3" in front of the rudder hinge line.


Laminating Film:

The "New Stuff" CP Premium Laminating Film comes from Laminator Warehouse in 500' rolls - essentially, a lifetime supply for one builder. Since there's a two roll minimum, I'd encourage you to do a group buy with friends and club mates

There are also various suppliers providing this same laminating film on a per-foot basis. This can be a great choice for your first build. Approximately 15' of 1.7mil and 5' of 3mil will be sufficient - although it depends entirely on the width of film being offered by your supplier. If in doubt, get more than you think you'll need - it's very handy to have on hand for repairs, and you may, like many others, be so impressed by its quality that you'll want to cover more of your builds with it.

There are five widths of 1.7mil and 3mil available:

I like using the widest widths of lam film available (27"), which gives you the most options for shapes and covering approaches. Many of the per-foot suppliers sell narrower widths, which are also fine, you'll just have to do more overlaps and will need more footage to cover the whole plane versus going with the wider film.

Laminating film is extremely inexpensive, and it's great to have more on hand for repairs, so err on the side of ordering too much - you'll wind up using it one way or another!


Hi All-

Well some of you may have seen the crazy-light builds that my friend Swiss Peter has been doing with the Le Fish, Spindrift and Big Fish. He has been achieving incredibly low finished weights using some insightful techniques that are actually easier than the traditional build in many ways, and result in a much, much lighter flying weight.

I've had a chance to fly his planes a good bit, and I totally love these designs at this weight. He was down at Torrey on Monday/Tuesday and put on what sounds like a really memorable show for the locals... maybe some who witnessed it in person can chime in

Anyways, thanks to him, I have been inspired to finally build another Le Fish! I've had this kit sitting in my shop for I don't know how long - years now - and I'm glad I held off on building it till the present moment. These lightweight builds really do result in a tangibly different flying experience than the traditional 38-40oz build and I'm excited to give it a shot.

So my goal is to build my plane to approximately 20-25oz. I had originally intended the design to weight about 25-30oz but the original prototype (and subsequent production planes) have been building quite a bit heavier, around 38oz. That's OK and to be honest, the stock build results in a tough, long lasting plane - I can still fly the original prototype, it's not dead yet!! - and for many people with good lift on tap all the time, or who are newer flyers just getting into aerobatics, that may be a good way to go.

However, the huge illumination of the lightweight build is that you can get the wingloading down into the 4-5oz per square foot range. That's as low as a Weasel or Alula, and you're talking about a much bigger aircraft... .that can do knife edge, rolling circles, and other rudder-mandatory moves!

We've been able to fly Swiss Peter's ultralightweight 17oz plane in as little as 4-5mph at Ellwood... this is pretty incredible for a big draggy fish-shaped aerobatics foamy!!

I will be using this thread to document in detail my build approach which draws liberally from Swiss Peter's advances. I am going to be implementing a lot of what Peter has taught me, but also doing a couple things my own way, mostly out of a desire to experiment further. Peter has a very nice flying 28oz Le Fish he built previously, that I really like quite a bit, and if this one finishes out to around that point, I will be very, very happy. If it's around 20-22oz I'll be ecstatic!

Tonight I started on the wing. I had Jack cut these wings with a vertical slot for a ribbon spar. These cores actually had two slots but I only ended up putting in one spar, and filled the other slot with heavily watered Gorilla Glue. I also glued a ribbon spar to the subtrailing edge and then... after Peter talked me into it... I cut holes in the wing. It's gonna be a Swiss Fish for sure now!!

Pics tell the rest of the story. I aim to have this plane ready for the July 9th VTPR fun fly event at Temple Hill. Wish me luck!!

Last edited by surfimp; Apr 22, 2013 at 08:36 AM. Reason: Video added
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Jun 24, 2011, 07:38 AM
Phil.Taylor's Avatar
looking good
here's some more Swiss holes for ya

Jun 24, 2011, 08:32 AM
Deniable plausibility
Shedofdread's Avatar
And whilst we're all being helpful, here's Swiss Toni ( Oh, by the way, nice looking aeroplane
Jun 24, 2011, 11:45 AM
Silent Flight
Twyl's Avatar
Heck, here's the whole family of Swiss.

Oh, and can't wait to see the entire build! Keep it coming
Jun 24, 2011, 11:51 AM
Phil.Taylor's Avatar
Oh No - what have we done?
Steve - Hope you've got one of these handy on the toolrack
Last edited by Phil.Taylor; Jun 24, 2011 at 12:08 PM.
Jun 24, 2011, 12:33 PM
Ninja Master
BigSwede's Avatar
Do you enjoy some of this while building?

Jun 24, 2011, 12:34 PM
Ninja Master
BigSwede's Avatar
Or maybe the company of one of these?

Jun 24, 2011, 12:41 PM
bjaffee's Avatar
Be sure to give us a clear signal when you are done...

Jun 24, 2011, 01:25 PM
1Corinthians 13:1-8
DWA's Avatar
Poor Steve. Will it ever end.

Looking forward to a good build thread from Steve and a good side show from the rest.

Jun 24, 2011, 04:11 PM
Phil.Taylor's Avatar
Time for Steve to get back to the build?

Jun 24, 2011, 04:24 PM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Expect another update soon...
Last edited by surfimp; Jun 25, 2011 at 11:25 AM.
Jun 25, 2011, 11:24 AM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Update: covered the wing in New Stuff laminating film. I used a single layer of 1.7mil and wrapped the wing from the leading edge back, with overlap at the subtrailing edge. That added 6g to the wing's weight.

Then, as an experiment, I wrapped the d-box top & bottom with a layer of 3mil. This significantly stiffened the wing to torsional flex, while leaving some pleasant spanwise flex. The 3mil is much heavier, coming out to 14g just for the d-box wrap. I am OK with the extra weight as I think it's just going to reduce noseweight requirements while adding strength. We'll see

Last edited by surfimp; Feb 14, 2013 at 09:37 AM. Reason: Clarified I used 1.7mil lam film
Jun 25, 2011, 11:54 AM
Flagstaff, AZ
dawsonh's Avatar

The build is looking very good so far.

Question: Where did you/Peter get the 1 mil laminating film?

I see the "New" 1.2 stuff at Laminator Warehouse:

The lightest stuff I have used on a wing is the 5 mi stuff... and recently using the 3 mil for balsa bits. The 1 mil stuff should be really thin... similar to regular iron on films?

Jun 25, 2011, 12:52 PM
Woodstock 1's Avatar
Originally Posted by surfimp
We've been able to fly Swiss Peter's ultralightweight 17oz plane in as little as 4-5mph at Ellwood...
I'm just about to start my second Le Fish build too, and, while I want to go light too, I'm puzzled as to how light to go. My local conditions tend to be mostly on the stronger lift side, I really can't see an ULTRA light Swiss-cheese build is going to do anything but get blown back off the slope... What sort of maximum conditions have this 17oz jobbie been flown in?
Jun 25, 2011, 07:08 PM
Airplane Killer
SumthinsFishy's Avatar
Cool! I've got my eye on a LeFish. I hope to be building one soon.

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