Estes Tercel: modifications & questions

I've been working on an Estes Tercel that should be ready to fly at my club's next launch. I did make a few modifications along the way:
--Added a motor hook to the motor pod
--Replaced the parachute with a short length of streamer
--Replaced the fuselage and pylon, made from two 1/16" pieces of balsa, with similarly-shaped fuselage and pylon made from 1/8" basswood. (I could have probably got away with 3/32" basswood and saved some weight, but I've had a bad history breaking the booms on my gliders!)

When packing my motor tube, it seemed like there's an awful lot of shock cord for such a narrow body tube. Has anybody experienced problems getting a good ejection? Perhaps I should trim the shock cord a bit? (It's good to see that Estes has finally responded to all the criticisms of short shock cords and Estes-dents!)

Recommended motors from the packaging are 1/2A3-2T and A3-4T; instructions also list A10-3T. A3-4T seems like too long of a delay, and 1/2A3 might be too little thrust for a fairly heavy glider. (I had a bad experience pranging my Estes Dragonfly on a 1/4A3-3T that barely got off the launch pad, so I definitely want to have enough thrust to spare!) Any suggestions on a motor? I'm definitely leaning A10-3T due to the short delay and initial thrust spike.

I've not flown the Tercel, but have flown many similar sized BGs. The A10 can be a real kick in the pants for a small glider. If Estes recommends it, I guess it won't strip the wings off. I prefer launching with an A3 but the 4 second delay on the A3 is too long for an optimal deploy for many BGs. I am guessing, but I think the A3-4 would still deploy at a safe altitude. Hopefully others with experience with the Tercel will weigh in.

I have seen light swing/flop wing competition models built by Chris Flanigan that deployed at apogee on an A3-4T perfectly. They were a sight to behold.

I am a fan of shorter shock cords on BGs, less likely to hang up on the wing at ejection. I worry less about the Estes-dents than about Red Barons.

The one thing I would recommend is to use a launch set up that maximizes the amount of launch rod available for your glider. Many people stick the BG on a regular pad which only leaves about 2/3rds of the the rod available to guide the model. What some do is pound a dowel or stake in the ground and tape a launch rod to the top of the dowel. Without the blast deflector and you can lower the BG down to the base of the rod and have the full travel available (make sure this doesn't present a fire hazard). This really improves the chances of a nice straight boost, especially on the 1/2A3 and A3 motors and if there is any wind present.

Good luck,

Don

shaped fuselage and pylon made from 1/8" basswood

Click to expand...

I've NEVER seen a Tercel body break. I suppose it is possible but highly unlikely. If you make it with the two layers of balsa and the piece of Tyvek paper in the middle the fuselage is supper strong for it's size. A stock built Tercel will fly really high on either an A3-4 or A10-3 motor. I would keep the amount of color finish to the model to a minimum to keep the weight down. You should get just about a minute of flight time on a full A motor. I've seen them fly away in thermals.

As for the long shock cord length, cut it to what ever length you wish it to be. I'd rather people say the shock cord is to long then too short since it's very easy to fix a long shock cord.


John Boren

The next time I build one, I'll consider an external shock cord mount, a la https://www.apogeerockets.com/education/downloads/Newsletter278.pdf. The BT5 tube just doesn't have much room for the traditional paper trifold anchor.

brewster_rockit said:

I've been working on an Estes Tercel that should be ready to fly at my club's next launch. I did make a few modifications along the way:
--Added a motor hook to the motor pod
--Replaced the parachute with a short length of streamer
--Replaced the fuselage and pylon, made from two 1/16" pieces of balsa, with similarly-shaped fuselage and pylon made from 1/8" basswood. (I could have probably got away with 3/32" basswood and saved some weight, but I've had a bad history breaking the booms on my gliders!)

When packing my motor tube, it seemed like there's an awful lot of shock cord for such a narrow body tube. Has anybody experienced problems getting a good ejection? Perhaps I should trim the shock cord a bit? (It's good to see that Estes has finally responded to all the criticisms of short shock cords and Estes-dents!)

Recommended motors from the packaging are 1/2A3-2T and A3-4T; instructions also list A10-3T. A3-4T seems like too long of a delay, and 1/2A3 might be too little thrust for a fairly heavy glider. (I had a bad experience pranging my Estes Dragonfly on a 1/4A3-3T that barely got off the launch pad, so I definitely want to have enough thrust to spare!) Any suggestions on a motor? I'm definitely leaning A10-3T due to the short delay and initial thrust spike.

Click to expand...

Mine does just fine on a 1/2A-2T motor...unless perhaps your basswood fuselage boom and pylon added too much weight. A10-3T is also a good choice. Delay is a little long on the A3-4T; model will be in a dive at ejection.

I second fulldec's comments about the launch rod. A club member loaned me his pad which was not only elevated on a dowel, but also was equipped with 4 extra rods to steady the wings at liftoff....a really good thing if you have any wind at all.

A3-4's will work great if the glider is well built and smooth, and would be my preference over A10-3's. With a piston launcher the nominal 4 sec delay might even be a bit short. Surface finish actually matters quite a bit; the increase in L/D usually more than makes up for the minor mass increase and will increase glide time in neutral air. Dope/tissue is pretty good since the model is strong enough for any mini engine. I'd definitely take the shock cord mount external and switch to kevlar since it will lighten the pod a bit and be easier to pack. If you further go to a teflon tape streamer you can dispense with wadding, or use a foam plug to get a more definite 'pop' at ejection to help assure clean separation. (OK OK I've flown gliders like this in competition for decades)

Can't say for sure about 1/2A not being enough. Risk of A power is that if the glider is built well and trimmed well, it can land pretty far off, chances of losing it are greater.

Pad-wise, here's a glider pad I worked up a few years ago. Based on PVC pipe. Glider is a R/C B/G meant for B power, 24" span (with Spooler Pod and L Hooks as mentioned in the mini-TopSky thread). Note the use of an umbilical to hold the clips so they do not snag the glider at liftoff.

Even if you do not build anything like this, do use the tip about an umbilical post of SOME kind. Even if it is an old rusty or bent 1/8" rod that is stuck in the ground, with the clip wires taped to it (Classic umbilical approach many people have used for decades).

I later upgraded it to have a second crossbar near the bottom, between the "T" for the legs and the post for the rod, with holes drilled into the outer parts of the crossbar to hold two 1/8" rods for the purpose of keeping the wind for causing the glider to rotate the wings into a bad position (wings under the micro clips can rally ruin your day at liftoff). Can't quickly find any pics of the upgrade at the moment.

UPDATE - Did find one that shows the second crossbar for holding guide rods to keep the glider from rotating in the wind. So, adding that one below the first.

Thanks for all the tips and years of boost glider experience that have gone into this thread! I intend to fly my Tercel tomorrow at the local club launch. 1/2A3-2T for first flight, possibly A10-3T on another flight if all goes well.

I ended up cutting 8.25" off the shock cord. I also cut the launch lug in half and glued both pieces directly to the motor tube (about 5" apart) instead of halfway up the pylon. Initial fit checks with the pylon-mounted lug seemed to indicate the launch rod could rub against the wing if the glider flopped too much. At some point I will probably build a second Tercel glider using my unused balsa boom, building new wings and tail using templates I made before building the current kit.

The ignition wire standoff included in the kit is a handy addition. Nowhere near as time-consuming to build as the launch pads designed for giving gliders a straighter boost, but should effectively keep the ignition leads out of the way.

Got three flights in today with the modified Tercel.

--Flight 1 on an 1/2A3-2T went straight into the ground after separation and never transitioned. Goes to show that a nice straight flight during hand-launch doesn't translate into a good boost glide flight. Best to trim for a slight stall so the glider transitions properly.

--I removed at least half the clay from the nose and launched again, also on a 1/2A3-2T. This flight went much better. Glider arced over after motor burnout, transitioned properly and made a nice loop around the launch site, touching down about ten yards from the pad.

--For the third flight I was determined to get one more launch in before the club broke the launch site down, even though winds were picking up. Would have probably been fine with a 1/2A3-2T, but I opted for the A10-3T instead. Predictably, the glider caught a thermal and started hauling to the northwest. Was still at a good speed and altitude by the time it was out of sight.

I will definitely build a new Tercel, since the second flight was a beauty. I might try using an A3-4T motor if the flight is early in the day and winds are still. I suspect the extra second of delay will mean a lower separation altitude, keeping the glider in sight longer.

Sorry you lost your glider but glad u got a good flight.