2m Spirit Refurbishment

[pinnedup]

I was given in older 2m Spirit, the plane is in good condition but needs a little TLC. There has been some repair in the fuselage tail, I plan to wrap this area with fiberglass. The fin was cracked and has broke off, this will be an easy repair. I have decided to refinish the fuselage, it was painted sky blue. I will also recover the tail fins. One of my concerns is that the stabilizer is about 3/8” off square, how adversely will this impact the flight? The stabilizer is epoxyed on and I do not see a clean way to remove it and wonder if it is worth the effort.

The wing is in good condition, although the spoilers do not work well, they operate off one servo and have a thin push-pull cable running to the spoiler, there seems to be a lot of resistance. The original owner said he could never get them to function properly. I saw a thread where Spider wire was used to pull the spoiler open and a rubber band was used to close them. This may be the set up on a new Spirit.

So my questions are:
With the stabilizer about 3/8” off of square, how adversely will this impact the flight?
Any thought on getting the spoilers to work well?

[ozmo01]

It definitely will take away from the performance.
Fix it perfectly straight and be EXTRA CAREFUL to not add tail weight.
Read around to find out how to change the wing incedence. There is a mod that works very well. Should be well worth a redo, but in sailplanes STRAIGHT
is a must.

[lincoln]

Actually, a Spirit is sufficiently screwy that the 3/8" tilt will probably only be a moderate effect. If you're going to fix errors of that magnitude, there are a lot of other ones to fix first. Here's what I suggest: Place the parts in your driveway. Compress them with your automobile's tires. This will enable you to do a proper rebuild. While you're doing this rebuild, it will be no more work and result in far more performance if you use plans for the Allegro Lite, Sovereign, etc. instead of the Spirit. ;-p

You can guess how I feel about the Spirit. Triumph of marketing over engineering. However, I can also guess how you'll react to my suggestion. So, here are some other hints:

-when using fiberglass, don't use too much epoxy. Blot it with toilet paper. It's ok if some of the weave shows through. Otherwise things can get heavy.

-the Spirit's tail is too short. If it looks like the repairs will be difficult, perhaps you should just cut off the last bit and extend it a couple of inches, while being very careful to measure the wood's density and use appropriate weights for the application. (i.e. ribs 6 lbs/ft3, spars maybe 10 0r 12, tip blocks really light, elevator maybe 8 or 10 lbs, etc.) Kit wood tends to be just any old wood and a lot of times it's too heavy. Other times, parts that should be fairly dense are not.

-consider if you can splice across the cracks with wood. It may be lighter for the strength.

-If the fuse is twisted and the tail itself is actually glued on straight, you might try taking off some of the top or bottom sheeting on the fuselage, jigging up the tail so it's twisted just a tiny bit the other way, and replacing the sheeting to hold the new twist.

-Don't put any Monokote on the spoilers. Sand them until they fit really well, but are not leaving large gaps either. Then use dope or water based urethane to seal them. Use 3M book tape for hinges. Use a torque rod to pull them back down. This is very easy to make and has the further advantage that there's no side force to make the spoiler creep over time. If you're gong to use pull string, you can glue little limit blocks under the corners of the spoiler so it sits perfectly flush. Even better, glue little blocks with little tiny wood screws in them (such as servo mounting screws) so you can adjust the height. If you use screws, you can glue little rare earth magnets (and I do mean little) to the spoiler where it meets the screws for a bit more positive retention. You don't need spider wire for this. Any old braided fishing line or just any old synthetic braided string with a really tight weave will work.

I don't know why the push pull doesn't work right. If set up right, should work ok. However, unlike a lot of people, I like the pull strings.

BTW, if you can't find a picture or something of a torque rod setup, get back to me. I'd scan a sketch, but I have to install the software after a computer problem.

[pinnedup]

Thanks funny lincoln but I will forgo the Goodyear rekitting method. I do not plan to invest too much time in the rebuild, but it may be a nice plane for practicing.

I was able to remove the stabilizer by applying heat with a hot air gun and working a putty knife into the crack. The stabilizer came off cleanly and the seat on the fuselage is in good condition.

Thanks for the advice.

[magee8578]

Lincoln,

I would like to see a picture of the torque tube. I was thinking of just putting a servo out under each spoileron, but would like to see what you are talking about.

[rdeis]

It's not *THAT* bad, sheesh!

Since you're without a fin, make the replacement fin 50% larger. Charles River has an article about fixing up the Spirit's bad habits, and that's the easiest thing for you to do that will make a big difference.

My V-tail Spirit initially had a huge dutch roll problem, then I made larger ruddervators for it. It's handles pretty well now, and wouldn't you know but that the equivelent standard tail to my current V has 50% more fin area! (Dumb luck there...)

[ozmo01]

I knew I had read about the MODS somewhere. This is a great site for glider guiders :cool: :D

charlesriverrc.org

[lincoln]

[IMG]It's more of a torque rod, and it's just for pulling the spoilers back down.I'll see if I can't attach a picture.

[lincoln]

Wire size greatly exaggerated. Spoiler to be activated using horn and pull string.

[rdeis]

I've also done actuation by torque rod. The servo pushrod attached to a horn on the rod, and hte spoiler blade attached to the rod with horns as well. It's neat and clean, but I doubt it was worth the extra work.

[pinnedup]

Well the scope of my Spirit refurbishment project has increased. I reviewed Dick Williamson’s recommended modifications on the Charles River RC webpage (charlesriverrc.org) and am incorporating some of these changes into my Spirit. I also fiberglassed the fuselage corners on the tail and nose. After removing the stabilizer, I lowered the rear of the stabilizer by 1/8” and decided to build a new 50% larger vertical fin and the rudder. After increasing the size of the fin and rudder, Dick Williamson recommends keeping the fin-rudder hinge line in the same position and angle as on the plans (in line with the elevator hinge line). Keeping the hinge line in the same position (in line with the elevator hinge line) would seem to move the additional weight of larger rudder further aft verses moving the fin and rudder further forward. However, keeping the rudder hinge line in the same position would effectively increase the length the length of the tail. Where have others that have increased the size of the fin and rudder positioned the hinge line? Recommendations?

This may seem to be a lot of effort for a free and marginal plane but it is fun and a learning experience.

[lincoln]

I've also done actuation by torque rod. The servo pushrod attached to a horn on the rod, and hte spoiler blade attached to the rod with horns as well. It's neat and clean, but I doubt it was worth the extra work.
The torque rod I show takes about 5 minutes to set up. You cut a piece of steel wire, put two bends in it, cut two pieces of brass tubing, glue them on, and stuff the wire in. That's it.

Actuating with a rod does sound fiddly. Actuating by a pull string isn't, in my experience, and you know you're not going to stall the servo.

[lincoln]

If you're making your own surfaces, and you pick the wood correctly, chances are they'll be lighter than the other ones, even though they're larger. If it was me, I think I'd try hard for max lightness, make them only a bit larger, and stretch the fuselage aft a few inches. The problem with the Spirit is damping, and this is enhanced more by lengthening the tailboom than by increasing the area of the surfaces. This requires that you acquire or make a scale, and use it all the time.

[pinnedup]

The spoilers in my hand-me-down Spirit do not work well, there is a lot of resistance opening and closing the spoilers. The spoilers operate off one servo with Cable Type Sullivan Gold-N-Rods running to the spoiler, the hinge on the spoilers move freely. The cables connecting to the spoiler are not well supported; the cable extends about 1.5 inches beyond the Gold-N-Rod sheath. The threaded push rod ends are long and move through a wood support with some drag. I could add additional cable supports at the spoiler end and possibly slide the sheath to cover more of the cable. I cannot see the rest of the cable route without removing more covering. I have considered upgrading the spoiler actuators to servos but would like to try to get this system working. The wing covering is in good condition and I would rather not recover it at this time.

Any recommendations on how to get the spoilers to work well? What other control cable/line systems are you using on Spirit spoilers or similar planes?

Thanks,

[sneasle]

I recommend the pull string method with a rubber band close. Pretty common design, should be some pics floating around the forums