A throw back

[Konrad]

Well, that took 4 hours to install the servos. Key was to make sure that the wire pushrods were a bit long so that I could use a kink to trim the surface.
Note; that I had to drill custom holes that matched the wire diameters I used (0.015" for the elevator and 0.024" for the rudder). The stock holes in the servo arm were 0.020 (0.5mm). I tried to make sure that the push rods were 90° to the servo arm running through the center of the servo output.

I also added the finger trap door in an effort to cut down on the drag this open hole would produce. It is working well, much better with a carbon leaf spring than the wire I used originally.

Now all that is left is the hard part, flight test. Right now she is setting in at 290 (305)grams. That's a loss of over 3 oz (90 grams)! I'm sure I'll have to add some more weight as it looking like she is rigged a bit tail heavy, even for me!

 

[Hank GB Z]

Hey Konrad,


She looks great. Can you clarify what you mean that "the push rods were 90 degrees to the push rods"? Do you mean push rods 90 degrees to the servo arms?

Thanks,

Hank

 

[Mucksmear]

Neato Konrad - I didn't have a Flinger, but I did build the Tercel around the same time as your build and I did indeed extend that wing hold-down bulkhead to the floor, I recall that my Tercel was more fun to build than to fly. Rolls were cute tho. Most fun I had with it was tossing it off the 6th floor of the dormitory tower I was living in, looking for thermals from the parking lot, mainly because it was novel.

I've always thought - what about using an atlatl (spear chucking lever) to launch these? Would a fuselage attachement directly on the CG (aligned both longitudinally as well as vertically) allow for pitch-free launches or would the forward rotation of the atlatl cause the model to launch into the ground?

 

[Konrad]

Hey Konrad,


She looks great. Can you clarify what you mean that "the push rods were 90 degrees to the push rods"? Do you mean push rods 90 degrees to the servo arms?

Thanks,

Hank

Yes. I'm glad someone is reading my posts in detail.

 

[Konrad]

Neato Konrad - I didn't have a Flinger, but I did build the Tercel around the same time as your build and I did indeed extend that wing hold-down bulkhead to the floor, I recall that my Tercel was more fun to build than to fly. Rolls were cute tho. Most fun I had with it was tossing it off the 6th floor of the dormitory tower I was living in, looking for thermals from the parking lot, mainly because it was novel.

I've always thought - what about using an atlatl (spear chucking lever) to launch these? Would a fuselage attachement directly on the CG (aligned both longitudinally as well as vertically) allow for pitch-free launches or would the forward rotation of the atlatl cause the model to launch into the ground?

I've never seen an atlal actually work for launching a glider. Too difficult keeping everything in alignment, meant that I never could get any consistency in the launch. A high start worked so much better!

Here are the last posts on my Tercel build. I should pick this back up after I get a few of my alpine ships out of the way.

 

[Konrad]

Here are some details on the trap door spring. It really is a waste of carbon, but it works so much better than the spring steel wire I was using before. The carbon goes aft 30 to 40mm of the rear wing opening. it is only glued down on this 40mm section.

 

[Konrad]

Just came back from tossing this off my little hill next door. This was in the early morning air and not looking for lift or thermals just a few trim flight. They are showing that I needed to add 15 or more grams to the nose. I'll need to see if I can fit a larger battery in the nose. Never got the plane fast enough to do a dive test. I still have some warped surfaces to straighten.

BTW; The trap door was working great.

 

[Hank GB Z]

I like the trap door. I might need to make one for the mucho mint. It’s hard to confirm from the pics but does the door hinge on the aft side or front side?



Hank

 

[Konrad]

The trap door is free, other than being attached via a carbon spring 40mm aft of the wing opening.
BTW; with my close up glasses I can see I had to add 21 grams of weight after the first test hops.

 

[Hank GB Z]

Thanks for the pics. That makes it much clearer. When you first mentioned the trap door I thought it folded up against a former in the fuselage. I kept thinking it would be complicated but seeing your system makes sense.

Hank

 

[Konrad]

Flew her some more. Now I know why I had abandoned what looked like a flyable airframe. There isn't enough bearing area for the pivot for the full flying stab. After having done the refurbishment it looks like I'll have to correct this engineering error. I should be able to extend the pivot bearing surface area 4 or 6 time larger than what I currently have without needing too much of a fin fairing.

This has been an emotional roller coaster. Finding a flyable ship in the attic. Finding so much fuselage damage under the covering. Finally getting a nice looking fuselage only to drop a 2x4 on her. Being on a high seeing that I've lost about 80 grams and now coming down with the stabilizer bearing area issue.

Reengineering somebody else's errors is difficult enough. Correcting your own errors is even more so. All I can say is that I'm not the same engineer I was 30 or 40 years ago, when I built this model.

 

[Hank GB Z]

At least you can make a good fix. Was the small bearing support issue affecting the flying qualities? Dropping 80 grams is really good.

Hank

 

[Konrad]

At least you can make a good fix. Was the small bearing support issue affecting the flying qualities? Dropping 80 grams is really good.

Hank

I think it might have been giving me some wandering. The stab is tilting* all over the place. I'll learn more after the retrofit.

I hope it will be a good fix. But I am known for improving things until they don't work!

*Stab tilting was a trim tool we used when trimming our free flight models. It had little effect on the power part of the climb. But in the glide we could using to trim the gliding circle.

 

[Shoelace]

That Tercel is bringing back some memories.

Hey Konrad, quick question: I was looking at your Tercel build page. Is your building surface ceiling tiles? I have heard that people like them. I'm considering using them, I've never used them before. I'm also wondering where one can purchase just a few as they seem to be sold in lots.

 

[Konrad]

They are balsa building boards. I think the one on the Tercel page is from Guillow Models but are no longer available. I like to make my own from Balsa lumber I get from my local hardwoods lumberyard. I cut these 4x4 posts into 1" thick blocks I then glue them with aliphatic glue into strips with the end grain exposed. I then glue these strips with a bit of an offset so that none of the glue joints line up. I then run this plank of end grain balsa through a surface sander. These last a long time as I don't think I've made a replacement in 20 years.

The reason for using pieces of balsa is to control warping. I like to make end grain boards as it helps with driving in pins.

Some folks do use ceiling boards. But I find their surface to be not as smooth. And the material isn't as durable nor does it hold pins as well as balsa. I can get low counts of ceiling board at my local Ace hardware store. No need to buy a pallet load from Home Depot.

I wonder why this question wasn't asked in the Tercel thread. Was it locked? This seems to be the fate of many of the threads. I wonder if there is a time lock in this forum for inactive threads?

 

[Shoelace]

Thanks, Konrad. You’re a wealth of knowledge.

 

[Konrad]

Thanks, Konrad. You’re a wealth of knowledge.

Thank you. But many think it is worth what you paid for it, and there maybe some truth to that.