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HelicopterScale Model RC Helicopters › Enstrom 480B fuse mold project
12-23-2013 02:08 AM  3 years agoPost 21
Mojave

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Palos Verdes, Ca.​USA

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Thanks guys

I'm currently working on filling the voids in the woodwork with polyurethane foam blocks and will be sanding this to shape. I'll post pics early in the week after the tail boom is complete.

RJ: Sorry for not addressing your previous comment. The Enstrom swash is located at the bottom of the heli, with the control rods inside the mainshaft. They exit the center of the rotor head and attach to bell cranks that connect to the grip via turnbuckles. I do have pics of this system, but given the complexity of mounting the swash under the main shaft, I'm looking at other options. I think that I may sleeve the main shaft and run the control rods in the cavity between the shaft and the sleeve. Right now my priority is getting the fuse plug finished, so that I can pull a mold from it. I can always fly the heli with a standard head while I figure out how to overcome this obstacle.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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12-23-2013 07:34 AM  3 years agoPost 22
R.J.

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SF bay area, CA USA

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Hi Barry,

I found some diagrams in the illustrated parts manual. Pretty interesting actually. I'm sure it can be done, but as you said, I think you will have your hands full for a while just making the fuselage.

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12-23-2013 08:39 AM  3 years agoPost 23
Mojave

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Yeah, I have the manual. The only way to do it that way is to have the swash on it's own separate shaft below the main shaft. This opens up a whole new can of worms. A 12mm hollow main shaft has just enough room inside for the 3 control rods to the head, IF there wasn't a bolt that connects the shaft to the main gear running right through the middle...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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12-23-2013 09:50 AM  3 years agoPost 24
PETER ROB

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Devon UK

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Hollow shaft's

Barry, RJ, Hollow shafts are not new to the model helicopter, they were used on a few models, in the early days, I can not remember the makers
More recently,Len mount had one on his Kiowa
From a fading memory there were bent rods, exiting through machine slots in the top of the shaft, connected to push rods to the blade grips
I think Len had his shaft drilled out by an old gunsmith, some thing hard to find in the UK now, but with your gun culture in the USA, I would not think it difficult at all
Peter R

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12-23-2013 10:54 AM  3 years agoPost 25
R.J.

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SF bay area, CA USA

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Hi Barry,

Well, the Thunder Tiger Raptor G4 has a hollow 15mm shaft that is readily available...don't know what the scale size of the mainshaft would be.

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12-23-2013 05:28 PM  3 years agoPost 26
Mojave

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Palos Verdes, Ca.​USA

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15mm-18mm is a good size for scale appearance on this machine. I forgot to mention that there's also the Jesus bolt at the head to deal with. Regardless of how you clock this bolt, it will always be in the way of the control rods. This is why I think that running the rods in the cavity between the main shaft and an outer sleeve is the best option. The rods would have to be bent at the swash end, then traverse through milled slots in the sleeve, up the cavity and exit through milled slots in the rotor head to connect to the bell cranks on top of the head.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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12-23-2013 05:47 PM  3 years agoPost 27
Keygrigger

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Mississauga, Ont.​Canada

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Just throwing out a thought here but would it not be possible to bypass a Jesus bolt that goes through the shaft and go with three threaded bolts that hold directly into the shaft? Also, a collar can be made to go around the base of the head to tighten it to the shaft with an appropriate slit cut in the base of the head? The head that I took off my 500MD TD had a through bolt but the collar on the base to snug down the base of the head. I think that multiple screws were used to fix the shaft and head of the various OH-58D's with their spooky looking radar/laser sights and AH-64's with the Longbow radar dome. Hope this helps some.

Don

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12-23-2013 07:07 PM  3 years agoPost 28
joeb56

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Newcastle,NSW -​Australia

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you can get a 16mm hollow shaft with a 10mm hole or a 20mm shaft with a 16mm hole from SDP-SI
They are case hardened but once you get over how to drill them they are excellent shafts
Cheers
Joe

On the J curve of all things Heli, I am still going down hill, FAST

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12-23-2013 08:51 PM  3 years agoPost 29
R.J.

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SF bay area, CA USA

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I was thinking like Don that the head would be clamped to the mainshaft and then screws into the holes in the mainshaft to take the load and prevent from rotating, but not all the way through the shaft.

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12-24-2013 12:22 AM  3 years agoPost 30
Mojave

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Palos Verdes, Ca.​USA

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All good ideas and duly noted Definitely food for thought. The head could be retained by the collar and a shorter screw used for an anti rotation device and to keep the head from parting ways with the main shaft.

The only problem with using the larger hollow shafts is getting a swash and auto hub that fit the larger diameter. In the case of the Raptor shaft, these components can be used, but anything larger would require custom machining parts. I have made custom shafts from SDI precision ground round stock, but have not seen their line of prcision ground hollow shafts. The raptor shaft isn't long enough to have the correct rotor height for this heli, so a new shaft would be in order (not a problem). If anyone wants to play around and design this while I mess with the fuse plug, feel free to post up your findings/solutions/failures.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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01-04-2014 09:42 PM  3 years agoPost 31
Mojave

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Palos Verdes, Ca.​USA

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Here's the latest: The foam has been cut and glued to the tail skeleton, now I need to sand/shape it, then glass it. The doghouse section has been fitted and the mainshaft location figured out. I also decided on Raptor E720 G4 mechs for this project, as it has a 15mm hollow mainshaft. I found a wrecked 720 for the donor and it looks like it will work out well. The swash will be under the main shaft on a separate stub shaft, with the rods going up the center. The servos will also be under the main shaft. I'll have to make a custom rotor head too. Anyone who sais that making a custom fuse is easy, is crazy Stay tuned...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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01-04-2014 09:53 PM  3 years agoPost 32
doorman

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Sherwood, Arkansas

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Interesting!!!!!

Looking good...

I am just wondering how the linkage running inside the shaft will attach to the head...but I will wait to see when you get closer to that... it will be a one of a kind!!!!!
Anyone who sais that making a custom fuse is easy, is crazy Stay tuned...
And you are loving every minute of it!!!!!

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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01-04-2014 10:59 PM  3 years agoPost 33
Mojave

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Palos Verdes, Ca.​USA

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Thanks bud Yeah, I'm having fun and the challenge is cool. But I sure bit off a big chunk when when I took on this project. Not because of the fuse, but the mechanical hurdle of stuffing the rods inside the main shaft. I could have gone the easy route and just used a standard head and swash, but it wouldn't have looked scale.

The rods will connect to 3 bellcranks on top of the head, just like the full size heli. The bellcranks will have a 1/3:2/3 ratio. This will require less articulation of the swash to attain the 6-8 degrees of cyclic. Enstrom has basically the same set up, so I figured why not copy a proven design.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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01-05-2014 12:36 AM  3 years agoPost 34
doorman

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Sherwood, Arkansas

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Still Scary!!!!

OK, it makes a bit more sense now....but still a bit scary!!!
BUT, I know you can pull it off!!
Gonna be sweet!!!

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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01-05-2014 12:47 AM  3 years agoPost 35
Keygrigger

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Mississauga, Ont.​Canada

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Just noddling out loud here. Looking at the actual head, I now see that the rods that will come up through the shaft, will be held in position by either the linkages at both ends or by guide tubes on the inside of the shaft. Essentially, you could use brass tubing held in position by two or three round plates with holes drilled in them for the pitch rod guide tubes to be soldered to. I am guessing that the swash will be installed on the bottom of the main shaft and that solid links as part of the rod will go from the swash to the rods in a fashion so that the rods and links will come out below the swash so that there is room for collective and cyclic movement. Kind of like the reverse of the head but without the links being pivoted at the edge of the head. The collective servos would still position the swash as they do in our normal installations. I am sure that those linkages sit far enough above the head so that it allows for some negative and enough positive pitch to occur. As to the swash driver, it can still be there as a single arm that attaches as normal to the swash plate only it would be upside down from normal. Man, I can actually picture that system in my head, lol. What an interesting project.

Don

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01-05-2014 10:07 PM  3 years agoPost 36
Mojave

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Palos Verdes, Ca.​USA

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Yeah Don, you're close with that concept... It's hard to envision, but I'll post pics when I get it situated. The swash will be on a separate 10mm stub shaft that will be inserted in a aluminum block on the bottom end of the mechs spanning the frame sides. There will be a gap between the end of the stub shaft and the bottom of the main shaft that will allow the "Z" bent control rods to enter the main shaft. The main shaft will protrude below the auto gear hub, which will be where the swash driver will fasten, then the driver link will face down and attach to the swash plate like it normally does. This will allow the swash to spin with the main shaft like it normally does. I may have to machine guides to keep the Z bent control rods from flopping over, but tubes in the main shaft could cause then to bind during cyclic inputs. I'll have to get creative on this part...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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01-08-2014 02:41 AM  3 years agoPost 37
Mojave

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Palos Verdes, Ca.​USA

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I'm making headway... The tail buck is sanded to shape. It needs a little filler in a couple spots, then I'll glass it. I'm very happy with the way it turned out. It's very true to the scale profile and shape. The cabin section is next.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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01-08-2014 03:00 AM  3 years agoPost 38
doorman

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Sherwood, Arkansas

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Look'n Good!!

Bud, you are on a roll...schweet!'

Stan!!'

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

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01-09-2014 02:56 AM  3 years agoPost 39
Mojave

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Palos Verdes, Ca.​USA

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Thanks Stan These are the Thunder tiger E720 G4 donor mechs. I swear they were built for this fuse! Now my little brain is working overtime on this combo...
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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01-09-2014 04:16 AM  3 years agoPost 40
Toby G 12

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Warwich QLD​Australia

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Looks very good Barry .
Barry what glue do you use to glue the foam to the wood ?

Greg

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HelicopterScale Model RC Helicopters › Enstrom 480B fuse mold project
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