Highlander Construction Tips and Links

First, check MAD Aircraft's construction tips at http://www.madaircraft.com/faq.html

Based on info I found at http://home.comcast.net/~aeronut/index.htm I used the lower servo for the rudder and the upper servo for the elevator so I could avoid any bends in the pushrods.  Figure 1 in the instructions says to do the opposite, but Figure 14 (see note on servos) says to do it this way.  I was able to keep them perfectly straight, no z-bends in metal and no curves in plastic.  See picture page for close-ups of how I routed them.  Also, use outermost hole on servo arm (use longest arm that comes with servo and cut all the arms off except the one you use -- also cut off servo mounting tabs) and start with outermost hole on control horns and move in on control horn if you need more throw (I used middle hole on control horns).  You have to drill out the servo arm and control horn holes for the heavy-duty Highlander linkages to fit.

The Highlander was the first R/C plane I ever built.  My Hitec Flash5XG radio manual said I could use the "servo reversing" function, so I did not have to worry about servo orientation.  I didn't worry about it, and sure enough I needed to reverse both servos.  No problem, worked great.  Until I installed the radio gear in my next plane, an Orion HLG.  No reversal for that model.  The first time I flew my Highlander again after flying the Orion, I forgot to change back the the "Model 1" (Highlander) program on the radio.  I launched with the hi-start, and up was down and left was right.  I crashed nose first at 100 mph  -- it happened to fast for me to realize what was going on.  Now I know using the reversing feature was a bad idea -- 10 minutes investigation would have allowed me to orient the servos where I knew they would not need reversing, and flying with the wrong "model" program set on the radio would just mean flying with an out-of-trim setup rather than a setup that is sure to lead to a bad crash.  So avoid using this feature when you can.

If you read the various stuff on the "aeronut" site mentioned in the first paragraph, please note that there is one piece of advice on that site that was submitted by someone other than the author that you SHOULD NOT follow.  If you reinforce your fuselage with a carbon tube (see Robert's tips below), do not follow the suggestion on the above site that you run your rx antenna through this tube.  I have been told by several people that doing so will significantly reduce the range (running an antenna through a plastic tube is okay, but not a carbon or aluminum tube).  Just cut another slot down the side of the fuselage for the antenna.

If you plan to use your Highlander primarily for thermal flying, you should probably build the polyhedral version.  It is simpler to build, only requires two servos, and will thermal slightly better due to the wing configuration and lower weight.  If you plan to fly it often on the slope as well, you might want to build the dihedral/aileron version.  In my case, I built the polyhedral Highlander for thermalling, and I built a dihedral version of the Dave's Aircraft Works Schweizer 1-26 EPP foam hand launched glider (HLG) to use on the slope (see the Choosing Your First Glider page).  Also, some experienced flyers may prefer the aileron version for the difference in handling even when thermalling, but new pilots will usually be happier with the polyhedral if they do not plan to use it on the slope often.

My Highlander kit was well made with straight parts, as I assume most Highlander kits are.  Apparently some kits contain warped foam and/or wood parts (see Mark Sullivan's pictures on my Highlander Pictures page and his construction tips at the bottom of this page).  If your kit is a mess, I would send it back.  If there are minor warps in the foam they can be easily straightened as you glue in the carbon rod, tape and cover.

This plane takes a good bit of lead in the nose -- be sure not to put battery so far forward that you have no room for lead!  I had to use 3.5 oz of lead, but my plane came out at the lightest end of the weight range listed in the manual.  Would have been lighter if I had replaced the coroplast with balsa, but I wanted the durability of the coroplast.

I molded my lead to the shape of my nose as follows:  Get used lead tire weights from a tire store.  Break off the metal clips, then tape lead pieces on top of the nose until it balances.  Put the lead pieces in a heavy metal can (like a soup can or other can from last night's dinner).  Squeeze one  edge of the can into a "V" so that the can has a pouring spout.  Cut out the shape that will fit in your nose from Styrofoam (not EPP), making longer towards the tail than you think you will need.  Take some sand, get it damp but not wet, and put it in another soup can.  Dig out a hole in the sand and put in your Styrofoam mold, then pack sand around it.  The portion of the mold that will go towards the nose should be furthest down in the wet sand, and the other end should be level with the surface of the sand.  Holding the can of lead on the top rim opposite from the spout with locking pliers or vice grips, use a propane torch on the bottom of the can to melt the lead (you can do it on the stove, but if your can melts you are in trouble).  Keep the torch somewhere where there is a piece of lead on the other side or you will burn a hole in the can.  Also keep the entire setup in a location where if you do burn a hole in the can the molten lead will not harm whatever it falls on.  When the lead is all melted, heat another 45 seconds, then pour slowly onto the Styrofoam.  The foam will melt away, and the lead will harden without getting any of the damp sand stuck in it.  This makes it easy to get a lead plug of the optimum shape to put way forward in the nose.

When purchasing your covering, keep in mind that there are different weights of Ultracote/Oracover (two different names for the exact same product).  The transparent colors (called "Lite" by some vendors) weigh less than the opaque colors.  The opaque colors are more durable and look better on EPP.  It is a trade-off, and I can't tell you which is the best option -- the EPP is durable either way, it is nice to have less weight, but it is also nice not to have to repair the covering very often.  I went with opaque red and yellow (see the Highlander Pictures page).

Unless you are concerned about the color scheme, I strongly suggest not covering the coroplast -- just leave it white.  This will reduce tail weight, thus reducing nose weight and lightening your plane.  Also, you can't heat the covering over coroplast, and trying to stick covering to coroplast with Super-77 and no heat is a really frustrating process.  Another note, be sure to spray the foam LIGHTLY with Super-77 and let it dry at least 10 minutes before covering - the Super-77 sticks to the foam well, then the heated covering sticks to the fully dried Super-77.  It doesn't stick so well to wet Super-77.

Tips from Robert Steinhaus posted to rec.models.rc.soaring:  "Prior to the existence of this FAQ/Tips page [MAD Aircraft's construction tips] I wrote this small note to help beginning Highlander/EPP foam aircraft builders. The following is a repost of that information.  The instructions for the Mad Highlander have improved but are still less clear than desired to guide a beginner (at least to foam construction) through the construction process without some worries and uncertainties. Unfortunately, most of the foamy manufacturers (DAW, MAD, Torque and Recoil) don't supply real building plans with pictures and clear staged directions like some of the better older kit manufacturers like Carl Goldberg, Bridi, Mark's Models, etc. I feel Household Goop has the best "grip" to the EPP foam and has at the same time great flexibility and give to retain the best shock absorption qualities of the EPP foam. Foam compatible CA might work in wisely chosen specific locations that are light stress (non structural) but I would prefer epoxy for joining wing cores and something like Household Goop, Amazing Goop, or Shoe Goo for most of the foam to foam or foam to coroplast joints. Foam Compatible CA is quite brittle and will crack on impact. Household Goop kind of bends and stretches (takes a lickin and keeps on tickin) on impact along with the foam. The leading edges are a problem area on the Highlander (and many other foamy kits). Generally the manufacturers don't provide a wood leading edge as this would sacrifice some of the crash resistance of the wing (even spruce or basswood will break before the EPP foam will be damaged on impact). Generally, foam can only be shaped with either a very sharp blade (new razor blade) or perhaps a hot wire (such as is often used to cut foam wings). I would suggest the sharp blade with care (the leading edge is semi symmetrical on the SD7037 and fairly blunt so you should not have to remove too much foam to get it close). A very light touch up with very very fine sand paper (>320 grit) could be used as a finish step. Generally most folks cover their foamy with film covering like Ultracoat. I have found that it helps to use some contact cement like 3M 77 on the high wear areas like the nose before applying the Ultracoat to cut down on alot of retouch work re-adhering covering later. I also would recommend that you consider covering the wing with a single piece of Ultracoat and not employ the more conventional top surface/bottom surface approach with a seam along the leading edge. Wrap the film around the foam wing in one piece with the seam at the trailing edge. A little 3M 77 at the trailing edge will help tack things down permanently and you will not have problems with the covering coming off in flight and the leading edge seams coming up. Since the Highlander has two tapered panels (main panel and tip panel) you may actually have to use two separate pieces of Ultracoat to cover these two panels but the idea is to avoid the seam along the leading edge and wrap the foam wing with a single piece of Ultracoat from top trailing edge around the leading edge to the trailing edge on each panel. Part of the magic of getting a really good flying Highlander is getting the right angle of the horizontal stab on the fuselage (incidence of the horizontal stab relative to the wing). Ideally, this angle should be around 1 to 2 degrees. The angle cut in the foam fuselage should be close but foam bends and flexes more than balsa wood and frequently many beginners apply the strapping tape with alot of tension thereby bending or warping the fuselage. This can play havoc with the horizontal stab incidence and change a great flyer in another foamy "dog".  Try not to warp the fuselage when applying strapping tape and film covering (don't use more strapping tape than recommended to help keep weight down). The Highlander fuse is a little narrow toward the tail and tends to bend more easily than desirable. I would suggest you consider reinforcing/stiffening the rear fuselage with something like a 3/16th (.187" dia.) carbon tube such as are used as framing material for modern high performance kites. Cut a shallow 3/16th inch grove into the bottom of the fuselage from the extreme rear to a point slightly in front of the rear wing saddle. Goop the carbon rod and glue it into the groove while supporting the fuse on a flat surface. Carbon rod like this can be obtained from kite suppliers like Kite Studio (phone: 1-800-KITE-991) (email:  kbiferrl@fast.net). I used Avia Linear Graphite Longs Part No. 1880 (Kite Studio order No. RLG1880L) and these cost around $2.80 each. Use something flexible like Household Goop on the coroplast to foam joints to give the best resilient flexible strength and crash resistance to these critical parts and do your best to get these tail feathers on square and straight (I actually use plastic drafting triangles while gluing these parts on). The Highlander is really a sound design and is tuff and crash worthy for beginners. I hope you have good experiences flying your glider!"
"I would like to pass along one other Highlander construction suggestion.  Coroplast, the same material used to make the horz. and vert. stab in the kit, also makes a fine reinforcement for the front of the EPP fuselage. In my area many large political signs are printed on coroplast and the signs can be removed the day after local elections as a public service. These signs make wonderful reinforcement for relatively narrow small cross section fuselages like the Highlander. I left the Highlander fuselage with rectangular corners as it comes in the kit and cut out two coroplast reinforcement panels which I glued with a light coat of Household good to the sides of the front of the Highlander (the reinforcement starts at the tip of the nose and extends back to a point two to three inches behind the back of the wing saddle). A length of 2" width strap tape is then wound around the front of the fuse generating a very tuff crashworthy fuse. This approach does add a little weight (>3 oz. approximately) so you may want to consider if you can afford the weight when thermal soaring (slope soaring is more tolerant of weight so this technique is more of a natural there)."
  Note from David:  I did not do the Coroplast fuse reinforcement since I plan to use my Highlander only for thermalling.  I wanted a light color on top and a dark color on bottom for visibility, so I also did not try to cover it in one piece as Bob suggests.  

Tips from Mark Sullivan of South Jersey Silent Flyers (SJSF) (see Mark's pictures on my Highlander Pictures page):  
My Highlander was built as an aileron version.  I used 3 mini servos and one standard size (elevator) with a standard 600MAH battery.  The tail was made with 3/16" balsa sheet.  The finished product weighs approx 34-35 oz with 1 1/2 oz of lead in the nose.  The following are my comments/suggestions about the Highlander Kit:

-  Upon opening the box, I was very disappointed to see that the trailing edge/aileron balsa stock was badly warped (unusable).  I've never seen such poor quality wood in a kit.  The manufacturer didn't respond when I wrote them about this.  I replaced it with balsa from the hobby store which had to be sanded and shaped to size.

-  You'll also notice that the fuselage has a distinct bend in it.  This is probably due more to the nature of EPP foam rather than manufacturing.  The fuselage is extremely flexible right out of the box and I had doubts whether it would be sufficiently rigid when completed.  I've read a lot on the net about guys embedding carbon rods in the fuse for stiffening, but I couldn't stand to add the weight.  I decided to build mine stock first and see how it turned out.  I figured a carbon rod could be added later if needed.  The completed fuselage turned out well within the acceptable range without the rod.  You will be surprised how rigid the structure becomes after gluing in the pushrod housings, taping, and applying covering.  One suggestion on gluing your pushrods:  It's very important that you build the fuse straight nose to tail.  Don't trust the "eye ball" method for this.  I drew a straight line on my building board and "jigged" the fuselage with weights on either side to make it conform to the line while the goop dried for the pushrod housings.

-  For the wing I decided to use 5 deg dihedral instead of 10.  I made my own joiner plate for this.  The foam wing panels are precut with angles for the polyhedral version.  If you build the dihedral only version you'll have to sand 90 deg angles on the panels prior to joining them.  I used a color marker to highlight the top edge of the airfoil at the end of the panels and used a "T" sander butted against the end of my building board to sand the 90 deg angle.  The line helped me make sure I was sanding evenly on the panel front-to-back.  The spar slots in the wing produced a very tight fit with the basswood spars.  So tight, as a matter of fact, the foam wing tended to conform to the curves of the spars.  To remedy this I sanded the spar slots with the "T" sander until the basswood spars could be gently pushed into the slots.  I then glued the spars in and butted the wing against my straight edge while the glue dried to produce a straight trailing edge.  Speaking of spars, contrary to the instructions I cut the spars for the outboard panel joints.  The end panels are tapered at the top, which requires a slight downward angle of the spars beginning at the end panel.  If left uncut, the outboard panel will raise at the tips.

-  I installed all of my radio gear as far forward in the fuselage as possible to avoid having to add nose weight.  Initially, I thought I got so carried away with this that the model would end up needing tail weight.  Once completed though, I still had to add about 1 1/2 oz of lead at the tip of the nose.  Don't worry about your model coming out nose-heavy.  I think it would be very challenging to build a Highlander that didn't need nose weight.

-  Make sure you heed the cautions with the taping.  It's very easy to introduce a warp in the wing and fuselage if you apply tension while taping.  Resist the urge to pull the tape taught as you apply it.  Let the tape "lay" down on the foam and smooth it out afterwards.  Also, when applying covering, make sure you completely cover the structure you are working on prior to shrinking the film "drum tight."  I attempted covering the bottom of my wing wrinkle-free prior to covering the top.  The film ended up pulling the airfoil out of shape as it shrank.  Tacking the film on the entire wing prior to using a higher heat setting will allow you to shrink the film uniformly.  Alternate between top and bottom for the final shrink.  EPP foam can take a lot of heat by the way.

-  If you are accustomed to building conventional balsa models as I am, you will run into a few frustrations with EPP.  The flexible nature of the foam will drive you crazy as you attempt to build a warp-free airplane.  Do the best you can and remind yourself that you're only building a "foamie."  It'll fly just fine even with a few minor twists and bends - I've proven it.

-  The flying characteristics of the Highlander exceeded my expectations.  The aileron version is very responsive and produces a very tight turn with the ailerons mixed with 100% rudder.  In my opinion, the sink rate is comparable to conventional balsa 2m sailplanes.  It responds very well to lift.  I'm looking forward to a long season of "stress-free" thermaling and sloping with this airplane.

Tips from Bob Smithson:
From my experience, I would suggest that before glueing in the control rods, put the elevator and rudder on temporarily, then figureing out the best location for the rods.  I followed the written instructions and think that the elevator rod should lay on the outside of the fuselage in the tail area.  When you cut a slot for it to be flush, this weakens that portion of the fuselage.  For the rudder control rod, having the rudder and elevator on would have allowed me to make a better alignment and eliminated a z bend in the control rod.  Also find that threading the metal control rods into the plastic is better than epoxying.  I would also have placed the clevis in the shorter holes in the servo arms.  Once taped in, they are difficult to get at and reset.
 
David's notes:  These are good suggestions, but be sure you want the clevis in the shorter holes in the servo arms if you do this.  Generally you want the outer holes in the servo arms -- I would not have been able to get the recommended amount of rudder and elevator movement without using the outer servo arm holes.

Greg Webb recommends MonoKote "Secrets of Great Covering".  It's only 50 minutes long and gives good hints on "how to's".

Many thanks to Robert, Mark, Bob and Greg for taking the time to share the above tips!!


Check out Dennis Hevener's Highlander Site for more Highlander pictures and construction tips.


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