Gyroc Build Thread

[Gillard]

The Gyroc was one of the early Estes releases (K24).
It uses helicopter recovery, where part of the fins move when the motor spits at ejection, the entire rocket rotates back down on its vertical axis.
i build a version of this rocket several years ago from plans of Jimz site.
This build is for a clone kit from BMS

 

[Gillard]

So what do you get in a Balsa Machining Services clone kit.
You get all the pieces to build a gyroc.

These include:

Laser cut fins
6.5 inch of BT20
Balsa nose cone
Engine block
Launch lug
2 flap holders
12 inch of eleastic thread
2 Vinyl hinges

What you don't get is the instructions, these have to be downloaded from Jimz site. You also don't get any decals, although Excelsiorrocketry sell the decals if you wanted to stay true to the original.

So are you just paying for someone to cut out some parts for you? basically yes, but the quality of the balsa and the laser cutting is excellent, as is everything else, including the thread and hinges - more bout them later.

 

[Gillard]

Before building the gyroc, I thought I'd just dry fit things together.
the only slight nag I have about the parts is that the rear flaps are slightly too long, not a bg issue, I simply cut the the overhang off.
the nose cone was also slightly larger than the outer diameter of the Bodytube. but that again was easy to sand down smooth to the tube, and I prefer to sand down than have to build up with filler.

 

[Gillard]

Built the fins.
Used CA gel to tack the parts together, and white glue to fillet.
the hinge is made from vinyl. there's been quite alot of complaints about using this type of hinge as the tape will eventually give way.
on my first gyroc I used nylon model aircraft hinges which have held up over the years.
I was very tempted to use my hinge cutter tool, which puts a slot into the edge of the balsa sheet, and then you insert a piece of mylar which is then pinned into the balsa.
In the end I went for the tape method given in the instructions, if it does eventually fail i will cut some slots. given that i'd got the kit i thought i'd try to stay as true to the original design as possible.

 

[NjCo]

I recall having one of these way back in the day. It worked pretty good for a few launches but eventually the elastic mechanism gave way and it came in full speed nose down with only the occasional rotation. I still have the nose cone from that rocket but most everything else was destroyed.

Couple of thoughts. I'd find another way to beef up the fin transition joint. I believe when I built this it was just a piece of tape or something like a sticky label. I would definitely find a way to make that joint a bit more substantial. Maybe something like a cloth tape would work. You want it to be flexible but still strong. There are a couple of alternative recommendations in the EMRR review page:

https://www.rocketreviews.com/reviews/all/plan_est_gyroc.shtml

The 2nd thing is that thin piece of elastic used to pull the rear fin into position for rotation. There has got to be a better way to initiate that transition or at least toughen it up a little. That was always the weak point in the old Gyroc and that was the part that failed in my model. I don't have any ideas off the top of my head but I would be very surprised if no one has come up with a better solution in all these years. Maybe look into how Apogee handles this in their Texas Twister which is essentially a 3 fin Gyroc:

https://www.apogeerockets.com/texas_twister.asp

I think they use a rubber band which isn't much better. Maybe someone will pop in with an ingenious solution.

 

[Gillard]

I recall having one of these way back in the day. It worked pretty good for a few launches but eventually the elastic mechanism gave way and it came in full speed nose down with only the occasional rotation. I still have the nose cone from that rocket but most everything else was destroyed.

Couple of thoughts. I'd find another way to beef up the fin transition joint. I believe when I built this it was just a piece of tape or something like a sticky label. I would definitely find a way to make that joint a bit more substantial. Maybe something like a cloth tape would work. You want it to be flexible but still strong. There are a couple of alternative recommendations in the EMRR review page:

https://www.rocketreviews.com/reviews/all/plan_est_gyroc.shtml

The 2nd thing is that thin piece of elastic used to pull the rear fin into position for rotation. There has got to be a better way to initiate that transition or at least toughen it up a little. That was always the weak point in the old Gyroc and that was the part that failed in my model. I don't have any ideas off the top of my head but I would be very surprised if no one has come up with a better solution in all these years. Maybe look into how Apogee handles this in their Texas Twister which is essentially a 3 fin Gyroc:

https://www.apogeerockets.com/texas_twister.asp

I think they use a rubber band which isn't much better. Maybe someone will pop in with an ingenious solution.

Having built a gyroc before, i pretty much changed everything the first time,
hinges and the elastic were the first to go. replaced them with aircraft hinges and the elastic with elastic bands, which did lose their strength after a few months, but were much easier to replace.
I want to build this gyroc stock.
Will probably bulid a third gyroc that is fully upgraded, for comparison.

 

[ScrapDaddy]

I think they use a rubber band which isn't much better. Maybe someone will pop in with an ingenious solution.

I think I have one! Put an eyebolt in a balsa BT20 block and tie 3 lenghths of Kevlar thread on, then attach the other end of the Kevlar thread to the spin tabs, then at apogee, gravity will pull the balsa blok forward, deploying the spin tabs, what do you all think?

 

[Micromeister]

the easier fix it to make the fin elastic strips removable.

because the model is not a very efficent Heli recovery anyway, it's also a good idea to add a third rotor/fin. this still brings the model in kind of fast but still slow enough not to cause damage.
sure I have a micro Tri-gyroc. it's a blast to fly it uses elastic thread on the fin flaps.

 

[ScrapDaddy]

it's a blast to fly:/QUOTE]

nice pun

 

[AstronMike]

the easier fix it to make the fin elastic strips removable.

One thing I typically do for my gliders, and even copters using elastic bands, is to have one or both ends tied to a paper clip. You can easily remove the clipped end from your fin/wing/elevator. For something as small as a standard Gyroc, the smallest paperclips are OK. I typically use the larger ones for most other things as I tend to build large stuff.

Speaking of Gyroc types, I have a 25" span one on a BT55 core tube that ejects a pod (yes, this is also doable retaining it as well). It uses black foamboard for the main fins and Readiboard for the other parts. Goes up nicely on a D12, and upon ejection, returns in a slower than youd think descent. This thing also uses elastic with a paper clip at each end. When its time to fly, I simply hook them up on the flaps and main fins.

 

[Gillard]

gyroc nearly built now, only got motor tabs to add. I will probably cut new tabs out from basswood just for a bit of extra strength.

 

[hcmbanjo]

Just be sure those tabs fit tightly against the engine.
Years back I flew the Gyroc for the first time. At launch, the tabs didn't hold and both rotor flaps - well, flipped!
Quick tight loop under boost and it dug itself into the ground.

 

[Gillard]

Just be sure those tabs fit tightly against the engine.
Years back I flew the Gyroc for the first time. At launch, the tabs didn't hold and both rotor flaps - well, flipped!
Quick tight loop under boost and it dug itself into the ground.

still haven't added them yet. although they are now made out of bass wood and are CA soaked.
will be putting them on "too long" and then sanding the edges back to the correct point.

 

[UrbanKnight]

I was kind of disappointed that this thread doesn't finish showing the build. I was hoping for a close-up of the elastic when installed, since I'm just about to do that to mine.

Just be sure those tabs fit tightly against the engine.
Years back I flew the Gyroc for the first time. At launch, the tabs didn't hold and both rotor flaps - well, flipped!
Quick tight loop under boost and it dug itself into the ground.

I figure you could always wrap a little masking tape around the engine for the tabs to be more snug.

 

[kjohnson]

I'll see about taking some photos of mine tonight for you. It's pretty straightforward.

Ignore the extra hole at the rear of the fin.. that was a goof.

Tie a knot in the elastic, thread it up through the flap/hinge and pull tight. Thread through the hole in the front of the fin, wrap around the front, and glue in place.

kj

 

[UrbanKnight]

Thanks! And just in time as I was going to attempt it tonight.