Goldberg Gentle Lady Build

CMS_1961

CMS_1961
Hey speedbirdted,

Your Gentle Lady looks great!!! Nice job on construction and covering!!

One comment>> those built-up stick push rods were the only thing I did not like in the GL kits --I know it is "old school" and all but they are in my opinion the weak link in the kit!! Those sticks over time will warp and change your flight control deflections for one, but the biggest issue is they can break or crack (most of the stick in the fuse out of sight) leading to partial or total loss of control of your plane. If the elevator stick breaks--it is over!

Had a guy at our field years ago was experiencing some elevator control issues at altitude??, next think you know his Gentle Lady was on the ground in the re-kit position--destroyed!! What he figured had happened was the push rod wood stick had broke in flight leaving the elevator to flap out of control. The problem is you can't do a check on the wood that is deep in the back of the fuse correctly. The rudder stick in the same plane was slightly twisted/warped from age as well. Some people use dowel rod with varnish instead of the square stock--not sure how long that lasts either??

My lesson learned from that was to use Nyrod for all the flight controls!! None of my GL's use that wood push rod. Not trying to scare you, and I am sure the wood is good for some years before you would have to worry. Just trying to save you problems in advance. Easy to put in Nyrod even after the plane is finished.
 

TooJung2Die

Master member
I'd guess a hardwood dowel would last longer than square stock.
You can use bamboo dowels. They're very light, stiffer than balsa and won't break. I use them for pushrods all the time. You can get them in various diameters sold as barbecue skewers; from thin dollar store variety to 1/4'' x 36" marshmallow sticks. Lately I'm trying carbon fiber rods and tubes instead of bamboo. I once compared the weight of same length 1/4" CF arrow shaft and 1/4" bamboo. The bamboo was lighter (and cheaper) but not as stiff.
 
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Turbojoe

Elite member
Before I knew about any other options I built several Goldberg kits in the early 80's exactly as designed using the provided balsa for pushrods with zero failures. I also built a stack of Eaglet 50 kits for the local flying club. I never had a problem with the balsa pushrods and neither did they. That's not to say I wouldn't use Gold-N-Rods today (simply because I have a large supply on hand) and I did so on my scratch built all balsa Eaglet 50. To each his own though. Today if I were to build another Goldberg kit and didn't have Gold-N-Rods on hand I'd use the kit balsa push rod method and not be concerned in the least. I've never (until the above post) heard of a balsa pushrod failure. That doesn't mean it can't happen I guess.

Joe
 

speedbirdted

Legendary member
My Kadet which was built in the 1970s still flies with its original balsa pushrods and I haven't had any problems at all with it. I have however heard of balsa pushrods deteriorating and failing in flight before. I think it has something to do with the readiness at which balsa will absorb moisture from humidity and keeping planes somewhere that the humidity changes a lot, or at least that's what I hear from the guys that I talk to at the field.

I did consider other alternatives to the pushrods, like goldenrods and pull-pull, both of which I'll take any day over balsa pushrods for various reasons, but I figured if the plan asked for the balsa pushrods I might as well just go with that since I figure the plan is probably not going to be faulty.
 

Piotrsko

Master member
Balsa is very sensitive to dry rot. Doesn't take much water to start the process, relative humidity is enough.

Straight grain hardwood dowel are decent if you can get grain that runs through full length. Takes me the wholesale box of searching to find those.

Nyrods, golden rods (Except for the metal interiors), whatever, all become brittle & take a set and become quite inflexible after 20 years. I have had them strip servo gears and break, so no joy there either.

All depends on how old the device is. Might be worth stressing the system as a test, or just arbitrarily replacing stuff.

YMMV
 

speedbirdted

Legendary member
Successful maiden alert!

maiden moment.PNG


I took it out the other day with the intent of doing a bungee launch however my 30 year old bungee broke almost immediately so I had to just have the other guy run along using the tow line. Only allowed about 50 feet of altitude but since we launched uphill this easily provided enough energy to use up the remaining runway and then most of the runway the other way when I turned around! I had to put it down going fast else it would have landed in the rough dirt and probably broke everything. Still it spun around on landing but didn't break anything. After that we tried towing it with the Cub which let me fly for long enough to get the thing trimmed out. Even with very little elevator deflection it has more than enough pitch authority - the big elevator helps! I had to add 3 ounces of nose weight to get it balanced correctly. The cg location on the plan looked a little tail heavy to me but I used it anyway and it handled fine. AUW came out at 22 ounces and honestly it flies like it weighs half that - so much wing!

Here's the video -

 

The Hangar

Fly harder!
Mentor
Successful maiden alert!

View attachment 162708

I took it out the other day with the intent of doing a bungee launch however my 30 year old bungee broke almost immediately so I had to just have the other guy run along using the tow line. Only allowed about 50 feet of altitude but since we launched uphill this easily provided enough energy to use up the remaining runway and then most of the runway the other way when I turned around! I had to put it down going fast else it would have landed in the rough dirt and probably broke everything. Still it spun around on landing but didn't break anything. After that we tried towing it with the Cub which let me fly for long enough to get the thing trimmed out. Even with very little elevator deflection it has more than enough pitch authority - the big elevator helps! I had to add 3 ounces of nose weight to get it balanced correctly. The cg location on the plan looked a little tail heavy to me but I used it anyway and it handled fine. AUW came out at 22 ounces and honestly it flies like it weighs half that - so much wing!

Here's the video -

Beautiful birds! @speedbirdted I can't help but notice your hat - are you a musician?