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MM Glider Tech F-80
Posted by Ken Nelson on Apr 28, 2003, 22:50

M&M GLIDER TECH F-80 SHOOTING STAR
Review by Ken Nelson

After building and flying two foam flying-wing slope sailplanes I wanted to try something else.  I liked the durability of EPP foam airplanes so I decided to shop around for an EPP combat scale fighter plane. While in the process of shopping around I got a flyer from Hobby People in the mail and they had the M&M Glider Tech F-80, F-86, and Mig 15 advertised. I went to their web site and looked around only to find that the F-80 was the only one in stock………sold!

The F-80 is a 48-inch span semi-scale EPP foam glider with a corrugated plastic (Coroplast) tail.  The manufacturer says it will weigh 23-25 Oz; mine weighed in at 28. The kit comes complete with EPP wings and fuselage, wood spars and sub-spars, plastic canopy and optional, droppable wing tanks (I built my plane without them), instructions and all hardware. The kit doesn't come with decals, it comes with a "logo sheet" which is supposed to be taken to a copy center and transferred onto sticky-back decal paper. The lack of decals is my only real complaint with this kit. I tried several copy-centers and couldn't find one that could do the work. I contacted the manufacturer with my dilemma and even offered to pay them if they could send me an adhesive sheet to finish the plane; unfortunately, they were not very helpful.  I ended up choosing a USAF Arctic Squadron color scheme  I covered the foam parts with aluminum and red/orange Ultracoat and painted the tail with matching red/orange plastic spray paint. The covering, paint, and Sig Manufacturing "Stars & Bars" decals were readily available at Greenfield News & Hobbies. I also bought a Squadron/Signal Publications book there that had great pictures of the F-80 and all the various paint schemes and detailing. The Arctic markings were colorful and seemed appropriate for Lake Michigan slope soaring February! The adhesive-vinyl lettering on the wings and fuselage was obtained at Hobby Lobby Craft Store. Except for the lack of decals, I was satisfied with the design and quality of the kit.

The instructions provided with the kit are generally good and should be easy to follow for anyone who has built RC foam airplanes before. A beginner might have a few questions but I'm sure the plane would turn out airworthy  The fuselage requires a good bit of sanding to shape but it goes pretty quickly with 40-50 grit sandpaper on a sanding block. It helps to sand in one direction only without too much pressure to avoid tearing out pieces of the foam (chunking). Shaping the fuselage is a very messy process so it helps to have a shop-vac nearby. The fuselage will also require cavities to be cut for the radio gear, elevator pushrod, and aileron servo/linkage clearances. The instructions provide a template to help with the aileron linkage cutout as well as a template for the wingtip shape  Mounting the radio gear involves cutting cavities in the foam for the gear and related wiring. I used a #11 X-acto knife for the surgery and it works fine. Take your time and make the radio gear fit as tightly as possible. Mount the battery-pack and receiver deep enough that you can cover them with EPP foam "plugs", this will help protect the gear and make the cavities easy to cover over.  One nice thing about this model is that it can use standard sized radio gear and it doesn't need any unusual radio mixing features so a very inexpensive radio can be used. I used a Hitec 555 micro receiver, 2 old Futaba standard servos that I had lying around and a 600-mah rectangular battery-pack that was also lying around.  The fuselage is pretty big so any receiver/battery-pack combination should work. One word of caution here: once the plane is finished and the wing is glued on the radio gear is sealed in the plane and will be very difficult to access without major surgery. Be sure that everything (especially the elevator pushrod linkage components) fits/operates properly before sealing the plane up for good. Another thing that I would suggest would be the use of metal-gear servos and/or RC car servo-savers to prevent having to cut up the plane to replace broken servo gears. Another option might be to use 2 micro servos mounted in the wing for aileron control. The wing has a thin airfoil for a foamy but if the servos are on their sides it should work fine. This would provide a number of advantages: first, the servos would be easy to access and remove if necessary.  Second, the wing to fuselage joint would be stronger because foam wouldn't need to be removed from the mating surfaces for the aileron servo and linkage clearances. Third, the wing camber would be adjustable to possibly allow the plane to be flown slower. One possible disadvantage would be the aileron linkage being more exposed to impact during combat and crashes.

For final assembly I taped then covered the wing and fuselage separately then removed covering where necessary for the wing/fuselage glue joint. Prior to covering the fuselage I recessed a 1.5 X 1.5 inch square of 3/8 plywood into the bottom of the fuselage forward of the wing saddle. I installed a 4-40 blind-nut in the center of the wood block and glued the block in place with epoxy. This setup allows for the installation of a removable bungee-launch hook made from 4-40 rod. Once everything was covered I glued on the tail and joined the wing to the fuselage with Shoe-Goo silicone adhesive. Be sure to get the wing positioned correctly and be sure that your aileron linkage is working correctly with no binding or clearance problems before the glue sets up  If you really wanted to it would be easy enough to make the wing removable with either hardwood blocks and nylon bolts or wood dowels and rubber bands. I was a little concerned that the wing wouldn't stay attached in a hard crash but I have had some horrendous, cartwheeling crashes with no problems so far. I cut the canopy to shape and slit the foam around the outline of the base of the canopy.  This allowed me to press the canopy down into the foam about 1/8 inch where it fit very tightly. I added some black Monokote trim tape around the base and it stayed in place with no trouble.  My F-80 needed about 1/2 Oz. of lead in the nose for balance. I cut a slit in the foam at the bottom forward part of the fuselage and wedged a piece of stick-on weight in the slit then covered the slit with tape. I chose to do this rather than following the instructions and cutting the battery cavity last for CG locating without adding any weight  I figured that a little extra weight on the slope wouldn't hurt and I avoided cutting up my nice covering job. My F-80 came out at 28 Oz. mainly due to the added lead as well as the bungee-launch mounting block.

The F-80 prowling the skies in Platteville, WI

After the F-80 was done there was no good sloping weather in the forecast so I took it out to the local RC Club and gave it a few good hand-launches. The plane needed some nose down trim but had a nice stable glide and a good glide ratio. Compared to my flying wings the F-80 has higher wing loading so it doesn't "float" as well and needs to be flown slightly faster to avoid stalling. On the slope this translates into a need for slightly more wind than you would need to fly a typical foam flying-wing. The next thing I tried was bungee-launching the F-80. I used some 1/2-inch tubing and the F-80 took off like a rocket! It was very stable on the launch with no tendency to "kite" at higher speeds and no flutter problems. A slight touch of up elevator and the F-80 was vertical and climbing like a scared cat going up a tree. I again noticed that the F-80 can't be flown as slowly as the foam flying-wings but as long as the speed is kept up the plane is very stable and tracks like an arrow. I got a little slow on a couple of landings and stalled the plane into the ground at various angles (all totally planned in advance for testing purposes of course) with no damage to the model. I initially had some concerns about the large Coroplast tail but I've found that this model can take serious abuse with no problems. I finally got a good day at Bender Park with the F-80 and had the opportunity to fly the model in good slope lift. The plane is very stable and very aerobatic. It tracks smoothly through loops and rolls and has wonderful inverted flight characteristics. The plane is very maneuverable as long as you maintain a reasonable minimum flying speed. The plane is easy to grip for hand launches and can be tossed into high winds with no problems. With the nose slightly down the F-80 will penetrate strong winds.  Due to its light weight, large fuselage and Coroplast tail the F-80 has a fairly low terminal velocity but it maintains what energy it has pretty well for a piece of foam.

The foam construction makes for great fun like inverted launches

The verdict: this is a really fun plane for bungee launching and medium to heavy slope lift and it really looks cool in the air!  It is stable, durable, easy to fly and very aerobatic. Everybody who has flown it has liked it.  The only damage the plane has sustained was a broken aileron control horn (2 minute repair) when the F-80 got "shot down" by Greg Smith's CombatWings XL during an impromptu combat session at Sheridan Park. This plane is a good value for the money and has very modest radio-gear requirements. With a "swap-meet" used radio this plane could be airborne for around $100.00. Even with an inexpensive, brand new 3-channel radio you could be airborne for $150 or less. Greg Smith has an M&M Glider Tech Mig 15 and when it gets built we will be able to re-create the Korean Conflict on the Lake Michigan shoreline. If you want to join in the action go to www.MMGliderTech.com to get your own foamy 1950's subsonic fighter jet and be prepared to check your six!

The F-80 at sunset





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