Apollo EP-5 ARF 72" Sailplane

[rockyboy]

I know they still make those larger "standard" sized servos for the giant scale crowd, but I haven't bought any since the 80's - I recently picked up a junk box at a swap meet included a handful of them and don't use them very often

Personally I think you'll be better off with the dual servo approach like you did, even though it'll require some arm trimming. Modern servos are much more powerful and reliable than back when this plane was designed, and with transmitters having plenty of channels these days you will have a lot more options for trimming and mixing via the radio with the dual setup.

 

[TooJung2Die]

Personally I think you'll be better off with the dual servo approach like you did, even though it'll require some arm trimming. Modern servos are much more powerful and reliable than back when this plane was designed, and with transmitters having plenty of channels these days you will have a lot more options for trimming and mixing via the radio with the dual setup.

That's the plan. I have spoilers and camber mixed in on the Sunbird glider. Works pretty good. The full length ailerons on the Apollo should make it even more effective. Standard 9 gram servos are going in for the rudder and elevator. I've used them on larger control surfaces than this. Like you said, modern servos have plenty of torque.

 

[TooJung2Die]

I am using the servo tray that came with the kit for the rudder and elevator. Instead of punching out the hole cut for full-size servos I glued it in place. You can see the outline of the cutout for the full size servos. Quite a difference.

Last task tonight was epoxying the rudder and elevator hinges.

It's crazy. All my other balsa airplanes were built using CA glue almost exclusively. This one is mostly epoxy. It wasn't easy finding 30 minute set locally. Big box hardware stores? Fuggeddaboudit.
jon

 

[TooJung2Die]

Here's a question. The rudder is raked and the push rod is at an angle to the hinge line. Do you install the control horn so it is at a right angle to the hinge line or parallel to the push rod?

 

[rockyboy]

I'd use a ball linkage and put the control horns parallel to the control rod. Not sure is that's the best way, but it's what I'd try

 

[TooJung2Die]

I thought since this Apollo is "ARF" it would be as quick and easy as throwing together some Ikea furniture. I thought it would be done in a weekend. Looks like that was a mistaken assumption. There is a bit more work than I anticipated. Got the tail feathers epoxied in place.

The control linkage in the kit for the rudder and elevator is ridiculously heavy stranded cable like you'd use for motorcycle brake cable. It might be suitable for full-size servos but not for the 9 gram servos in there now. I'm using the usual guide tubes and .032" push rod wire. Serious weight saved. Ounces.

Since I don't have ball linkage the control horns were installed at right angles to the hinge line and the wire bent to align. I put the adjusters on the control horns.

The plan has the elevator control horn on the bottom side. I put it topside so it stays out of the dirt when landing and "up elevator" is pull on the horn instead of push.

jon

 

[TooJung2Die]

Deviating from the plans again. The manual says to attach the canopy to the fuselage using 4 wood screws. How are you supposed to remove the battery to charge it? I can see myself dropping screws in the grass at the field when changing the battery. I guess the original had a NiCd battery pack charging connection outside the fuselage. Plus there will be a big ugly open hole under the canopy. Here's the rough trimmed canopy sitting on the fuselage so you can get an idea of what the manual says.

I made a removable plywood hatch to cover the opening in the fuselage under the canopy. The canopy is screwed to the hatch with 6 tiny screws from micro servos. The hatch is held in place by eight magnets scavenged from a dead motor. These magnets are strong. You can pick up the front of the airplane by holding the canopy. No worry it will come off in flight.

That looks better and makes battery access easy. The bare wood under the canopy will be painted. Probably black.

I haven't bought a battery for it yet. When I know how much weight is needed to get the CG right I'll buy a 3S battery the same weight.
jon

 

[TooJung2Die]

That looks better...

She's a big one.

jon

 

[Captain Video]

Niiiiiice!

 

[kdobson83]

Man, your giving me glider fever. I've never owned/flown a glider, may have to look into it. Might have to get the FT Night Radian as an entro into this leg of the hobby. There's something appealing to a large glider...

 

[TooJung2Die]

Man, your giving me glider fever. I've never owned/flown a glider, may have to look into it. Might have to get the FT Night Radian as an entro into this leg of the hobby. There's something appealing to a large glider...

You could build the FT Simple Soarer instead. I got back into gliders by building the "OSG" (one sheet glider). One sheet of Adam's foamboard and you have a 60" sailplane. I like gliders because they're a better fit for my piloting skill (or lack thereof). It's like flying a kite way up high only there is no string attached. All you need is a couple of batteries and you can fly for hours.

 

[TooJung2Die]

She's hefty. Empty the Apollo weighs 2 lbs, 5 oz, or 1054 grams. It needs a whopping 14 oz in the nose to balance the CG! The largest battery that fits under the hatch is 2800 mAh 3S. That battery weighs 7.5 oz. That means it'll need another half pound of lead to balance the CG. I got the lead.

If I built this airplane it wouldn't have a solid balsa and plywood tail section. It would be a lighter built-up open construction. Looks like that big old brushed motor it came with was useful ballast.

 

[Joker 53150]

Looking good! I've got a couple glider kits sitting on the shelf to scratch a future itch. The elegance of the lines is very appealing.

 

[TooJung2Die]

Remember when Joker asked;

AUW of 3 pounds? Sounds like it's made of lead!

She's not made of lead but it takes a good size chunk of it to get the center of gravity right. This is the stack of eight 1 ounce pieces of lead it took to balance the Apollo.

Experience has shown that the CG in the plans is often too far back for the maiden flight so the balance point is a little forward. If it's nose heavy that's great for the first flights. It will be easy to remove ballast one ounce at a time.

I've read that many gliders of this size have pounds of lead ballast added to make them heavier. I can't wait to see how this three and a half pound glider flies. Next post will be of the test glide and hopefully a maiden flight.
Jon

 

[TooJung2Die]

Maiden Flight!

Test glides proved the CG was close and at least it wasn't tail-heavy. It takes a bit of strength to throw it at the speed it needs to fly. The maiden flight was flawless. No trim required. Any concern about the weight of the glider was unfounded. It NEEDS the weight to penetrate and maintain airspeed. The 2835/1350KV motor with 9x5 folding prop has plenty of thrust. She flies for about 30 minutes on a 2800 mAh 3S battery. I wouldn't change a thing.

Build slideshow and short flight video:

The flight video begins at 1:28.

jon

 

[L Edge]

Man, your giving me glider fever. I've never owned/flown a glider, may have to look into it. Might have to get the FT Night Radian as an entro into this leg of the hobby. There's something appealing to a large glider...

If you are going to try a glider, I suggest the Radian(do not need ailerons, rudder/elevator is sufficient) . I have been flying gliders for years and this is the one to pick. Its lightweight, flys good when windy, power pack is tops with a 1300 . When you learn to fly it, by changing the CG, it will slope soar as well as thermals.
Watch the video with a camera rubber band to the bottom of the wing and see how quick it got up to 1797 feet and back.(go to end of video). It is almost as good as a plane can do. Highest I made it was stuck in a thermal and went to almost 2700 ft by reading altitude from meter.
I triangulate and concentrate when it is up there that high. That is, have a reclining lawn chair where I position my eye(fixed head) and move the transmitter antenna on my knees to line up where the glider is. That way, if you lose it, you can find it.

Belonging to club, sometimes too many people at field, so I put the glider up and enjoy flying rather then waiting in line.