SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old May 28, 2012, 07:42 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
3,932 Posts
I knew it..... I posted to late I would definitely route out some of the ply between the sticks to save some weight. As I mentioned you just need to tie all the sticks together. "E" power so no vibration to contend with.

The spot where the sticks tie into the rear wing saddle is what I consider the weak spot. Again 1/64 is all you need. You just need to tie the sticks to the wing saddle

I used 1/8" Robart hinge points on all the control surfaces. The "knuckle" will be buried in the surface a bit. Same deal for the elevator and rudder. The ailerons are the worse. When done they are pretty slick as the design "seals" the gap. I may have used some brass or aluminum tubing to support the hinges of the ailerons as the hinge line is out of the wing quite a ways. 1/4 tubing is a very good fit over the 1/8 hinge point. I don't remember but if "point pockets" are available for the 1/8 hinges, that might be a better alternative than the tubing. Hinge the rudder and elevators first to get a good idea of how it all works first. In fact I would drill the holes before I commenced to rounding or routing to get ensure getting the hinge holes properly placed. The hinge pin will be buried one half the thickness into the control surface. So, if the control surface is 1/2 inch thick, the hinge pin will be 1/4 inch deep in the control surface. It looks funny at first. You may want to try it on some scrap to get the feel for it. Just cut a slot for the hinge to work in.

Starting post 35 I had to replace hinges after one broke see here...

http://www.rcuniverse.com/forum/m_10...mpage_2/tm.htm

I would be very concerned about the glue holding the sheeting on the wing after being separated like it was. Give the wing panel a good twist to see if it starts to delaminate again. What's going to happen when you take the bird out in the sun again........ I think I would just have some new cores cut. The old core could be used make templates. Are you in a club? Does anybody in the club have wing cutting equipment? If not there are people that do this for a living. See here....

http://www.flyingfoam.com/FCCapabilities.html

I believe there was some washout in those wings. I think it was detailed on the plans?????? That can be cut into the new cores with ease. IMO this would be money and time well spent. Yes I know, more expense....and time.....but the wings are kind of an important part of the airplane

I put servos in the wings for the ailerons. IMO the best way to do it. I think I may have been the first at our club to do this???????????? I'm probably wrong on that point


Ken
kenh3497 is offline Find More Posts by kenh3497
Reply With Quote
Sign up now
to remove ads between posts
Old May 29, 2012, 09:28 PM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
Well the ailerons are tucked in nice & tight, most likely too tight. I will need to deciede on if covering the area of interface or painting them. I went w/ the SIG "wierd & crazy" design. Actually they feel nice. Not glued in just yet as they are still requiring some more setup, centering & sanding. Ken mentioned the Robart hinge points which I had none on hand and I got antzie (follow the modern directions and all)

Ken....
I'm always a day ahead of reading your proven tried & true advice! I had to only plug half of my aileron mounting holes...so far! And I noticed that the 1st one (I did them first~) outside edge is sitting a tad high. Their not glued in yet, so not much bother to do it right the first time,,,well the last time I say then. Man, these things are a complete hassel. But ya, ya, ya, the'll look sweet when their done.

Wing cores, Good idea on placing them back in the sun. It's time to see what I have really. Some torsion, but how about some "balsa right" or some type of coating. Jury is still out on that.

I've investigated on the Flying Foam's website before. I believe they can repro the cores, but because of the complex foil, it will be a close copy at worst. I have no problem with glassing the wing. I believe I will save a few ounces overall from the proposed 7lbs, but if I'm going to gain a few it would be OK at the wing.

The weak, another weak spot, second one in a row I could say?
So thar she blows. If that's not one I don't know what would be. Any ideas? I have so many about this I don't know where to start ~

Ken, Hope you are healing well. Back to the shop.

DC
43851E is offline Find More Posts by 43851E
Reply With Quote
Old May 29, 2012, 09:48 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
3,932 Posts
Your pin vice has the other weak spot pin pointed

It sounds like you are practicing on the old wink so when you get the new one it will go fast!! Done right glass, epoxy and paint is not any heavier than monocoat or any other iron on. Some say the water based polyurethane finish is lighter than epoxy. You trade a bit of ding resistance though for the lighter weight.

I would investigate cutting your own cores. See if another local modeler can help or has the equipment. Cutting foam cores is not rocket science. I did a set for my CAP 232 and they turned out a tad lighter than the built-up wing they replaced. I reconstructed a cutting bow and had a friend help. It took about 40 minutes to cut the two cores. I would have been less time but we spent too much time talking

Ken
kenh3497 is offline Find More Posts by kenh3497
Reply With Quote
Old May 30, 2012, 09:11 PM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
HA ha! But the bench flying is still flying.

I have already some parts to build up a decient hot wire, few light dimmers, step down xmf, plenty of light gauge guitar wire. Even a "C" shaped something or other. Been talking about it for ever. Perhaps now could be the time to start in. It's already hot here in Texas pushing mid 90s and I've been inside "playing it cool" like a sissy hold up in he hobby room. I only go to the garage for the jigsaw & belt sander, and a cold one in the "shop fridge!"

Glass over the sheeting, hummm. I can see the corner I'm in better & better lately. I think tonight it will be the fuselage & I in a stare down contest. Actually I love this part.

The weekend is creeping up & looking at some eflight electric retracts for this plane maybe.

Thanks again Ken for all your help. How graced am I to find yourself who has been there & done that (this).
DC
43851E is offline Find More Posts by 43851E
Reply With Quote
Old Jun 10, 2012, 12:52 AM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
It's midnight & finally shutting down for the night.

Motor- looking at something in the 35mm realm to reproduce the .60 power. Maybe on 4 or 5 cells. If I have to wind something I will because I'm that cheap!

2nd week spot fix was installing a gusset and an additional crossmember across the back of the gusset. It took me a few takes on exactly what to do, but as mentioned in a reply in this thread, it was certainly an issue, but I think I added the additional stress relief required.

Cowling- from 1/8" balsa. I wanted to shrink a bottle, but actually this was faster. Now how to fasten with balsa? May run a thin metal strip at the rear so the panheads won't sink into the super soft balsa. Trying to keep the cowling to fuse gap small on this one except at the bottom where it overhangs a bit. Access will be tight with only a small battery hatch for the 4000mah 4s.

Locating the wing- I love doing this on all my scratch builds. It's such an important part of the build. I had to sink into the foam at the LE a 1/4" plywood tounge inserted about 2 ". Never messed with a foam wing this large as I normally prefer builtup wings. So it was backfilled w/ epoxy and attached to so added structure at the LE to blend the wing to the fuse. The wing uses 4 bolts, 2 in front, 2 in the rear.

Control surfaces are all fitted and set aside for installation of the monocoat. The entire plane will receive the "Jet White" Monocoat. Then the rest of the typical Akrobat trim scheme. The fit of the moving surfaces may require additional work as at least now there is no light between the mating surfaces. On the moving surface it's LE will have Monocoat applied, however the receiving part of the main wing, vert & hortz stab will not at the inner surface. I'm leaning towards "never again" on this type of turbulance shielding. We'll see.

Retracts? Why not. They will not close up & forward as scale. Rather to the side as these new cool Eflite units don't turn. I do plan on turning something from some 6061-T6 for the lower landing gear, maybe even some suspension. These retract units went for $129 and are good up to 9 lbs says the data block. This plane should be around 6lbs AUW.

Last pic, well....!

May install the retracts Sunday. Take care all!

DC
43851E is offline Find More Posts by 43851E
Reply With Quote
Old Jun 12, 2012, 08:46 AM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
3,932 Posts
the top of the cowling overlaps the fuselage a bit. Take a look at some photos on the web. the wheels fold strait back and do not rotate to lay flat in the wheel wells like a corsair. again look at some photos on the web. it might have been a good idea to add some spars when the wing was sheeted if using retracts in a scale like fashion. of course you are far beyond that point now.

how did re-gluing the wing sheeting work?

ken
kenh3497 is offline Find More Posts by kenh3497
Reply With Quote
Old Jun 12, 2012, 02:41 PM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
What a dummy I am! When I was about done w/ the Rt side, realized that these retracts would work w/o turning. Guess I just wanted to see 'em completly hidden. At least that is what has happened. and it looks very nice. Pic to come. There was a bit of spar grinding, but it was at the very end taking off the last 2 some inches & about an inch & a half down.

I've found not alot of pics of the 526? But did find a cool vid of the plane taking off and climbing almost vertical. Maybe you've seen this one.....

Zlin 526 - "Acrobat" - TAKE OFF - (1 min 16 sec)


More soon. DC
43851E is offline Find More Posts by 43851E
Reply With Quote
Old Jun 15, 2012, 01:29 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
3,932 Posts
Try looking here

http://www.airliners.net/search/phot...rliners.net%2F

Pics of the "AS" model are as rare as hens teeth though.....
ken
kenh3497 is offline Find More Posts by kenh3497
Reply With Quote
Old Jun 15, 2012, 08:18 PM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
Try looking here

Thanks again Ken. What a selection of images. Should be able to decorate this plane nicely. Seeing those pics makes me think what a sweet plane this actually is.

Working on the 2nd gear tonight & Saturday. Hopefully will post a vid on the finished pair. I have to say that I am somewhat impressed in Eflite's electric retracts however one did not work right out of the box! The wire was laytex'ed (strain relief'ed) and was never soldered. I just was gently pulling on the wires of the DC motor and one was exceptionaly "stretchey". Cut back the white laytex & there it was, a wire that had not been tinned even. So tinned it & soldered it onto the pad & it worked. I guess soldering was attempted, perhaps stuck only w/ rosin flux. Comes w/ a "Y" harness and a pin pushed out breaking the hold-down tab. Cutting the strut was extreamly easy, a little too easy for me. I was thinking it was quality steel. Well we'll see. The lead screw to motor shaft alightment is not very good w/ the motor changing pitch (rpm) while actuating the gear. Maybe the leadscrew is bent a little? Horizon Hobby is top shelf in customer service for me...so far. Hope I have no complaints during the service life of these. I may send them in and see what they can do when the plane get's closer to final assembly or at least let them know what my initial impression is after the first 20 cycles on the bench.

OK, back to the shop. Listening to a website's audio called "Last FM", endless good music>
www.lastfm.com
43851E is offline Find More Posts by 43851E
Reply With Quote
Old Jun 15, 2012, 11:39 PM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
For you that follow this thread I wanted to mention 2 special techniques that are used that have never failed me-

1) making threads in wood with a standard tap, but using a plumbers pipe dope. I use a teflon crayon found at Home Depot. Then follow up w/ CA in the hole, followed up before the CA sets with the fastener with the teflon "wax" applied then inserted into the now threaded hole. Even w/o the CA, I have never had a thread fail. Used in motor mounts, screwed on stabs, and now retracts. I'll see if it holds tight, but I'm thinking it will be fine. I'm normally ok on landings, at least the ones that have the shinny side up

2) use your calipers as a scribe? I know this can curl hair, but on balsa, why not? I have an old pair that are use soley for scribing on all materials and if you're used to working w/ marked lines, it's a nice & very accurate way to layout designs on material being prepaired for cutting.

Working mostly on the wing for the last week solid. Busy at work the last 4 days, but back in the "purple grotto" now. Know who used to talk about his "Purple Grotto" anyone?

I've selected a ball bearing servo for all the control surfaces that is made by Futaba, but is a low end design that is extreamly reliable. S3004 costs $13.99 at my local Hobbytown where I purchased 3 to proform all the flight control functions. Currently only the aileron servo is the only one installed at this time.

After the retracts are installed it will be back to the fuselage where the other 2 hortzontal & vertical stabilizer servos will find their place and be mounted, and the acuation method will be determined (pull-pull or not). The pull-pull method is nice, but requires an extra control horn on the stab surface, and I kinds wanted to ke this bird as scale as possible.

Power plant- something in the 35 to 40mm realm. I have a couple of used, but still good motors to size up the front end with. One thing for sure is that this Akrobat will have long (+1 inch) standoffs ahead of the firewall for the "X" mount.

Time to cruze around the site for now, back to the build tomorrow AM

Doug
The fuse will wait another day or so.
43851E is offline Find More Posts by 43851E
Reply With Quote
Old Jun 16, 2012, 12:01 AM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
how did re-gluing the wing sheeting work?

Hey Mr. Ken, I was just reading back & realized that I never mentioned the results of the "hot test". All the other (old) seams failed! But the newly repaired ones stayed firm. In the sun for about an hour and a half, laying on the grass I saw the old epoxied joints failed. I mean to say that the seam seperated, however the contact cement did hold it's own and the sheeting stayed flat. This sheeting cement is still tacky after how many years. Crazy. So CA'ed it with the medium "purple label" stuff when it was cooled off, as the old seams were tight fitting. Soaked it in about an 1/8" on both sides and held it flat with my hand & sanded next day. I went over the entire wing looking for cracks again. Found maybe a couple at the edges and soaked them just to be sure. Back in the sun late that day for about 2 hours. It looked alright, so then a friend & I tried the twist test you mentioned. Well I can attest that it's solid. We depressed the wing w/ our hands attempting to torsion it, it twisted about a half inch maybe wing tip to wing tip, but the pressure we placed on the sheeting doing this test proved to me that it was solid & all the seams held tight. Whew. So much so that I thought it was time to consider some retracts and filler. Finish sanding will hopefully be this weekend or soon with 360 grit red paper (Gorilla brand). Wondering about some "Balsarite" or just coating it with some urathane?

Flying an electric torch is why I'm not going the route of silkspan & dope. Last year this whole state was a tinder box, and as many can attest (ask me how I know) electrics follow right on through after the crash with the (scale appearance) LiPo fire so, going to try & keep this bird low on the "nitrates" if 'yall know where I'm headed. To quote Donald Southerland in "Kelly's Heros" playing "Oddball"..."enough with the bad vibes already" (speaking to none other than Don Rickels)

Take care, Doug
43851E is offline Find More Posts by 43851E
Last edited by 43851E; Jun 16, 2012 at 12:10 AM.
Reply With Quote
Old Jun 16, 2012, 09:04 AM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
3,932 Posts
I see there are push rods out to the ailerons. The Zlin was the first plane I used separate servos on the ailerons. I have to say I was very happy with that setup. Maybe to late for you but a possible option if all else fails. They were "Royal" brand mini's and only had about 20 in.oz. of torque if I remember correctly. I still have them, but could not find any data to back my claims.

It's looking good so far. Once in the air, you'll love how it flies. Maybe I'll get back to my Zlin soon.......or not......

Ken
kenh3497 is offline Find More Posts by kenh3497
Reply With Quote
Old Jun 16, 2012, 11:51 AM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
So you still have your Zlin Ken??

The Zlin was the first plane I used separate servos on the ailerons This was perhaps THE only thing I was happy with as found. The internal bell cranks seemed well installed as they moved with ease. So went on ahead and installed a single servo in the middle where the previous builder had run the control rods to the center cutout. I had to break through to the other side to have enough room to get things hooked up. Used ball links as the alignment was not perfect I was glad to see that installed and moving, the servo did not complain and centered every time using those blue plactic rods w/ yellow jackets, Forget the brand, but they are working well.

What a sexy looking plane this is. It has a P-51 look to it at the vertical stab & in the wing, a cropduster kind of nose, and fairly modern (50-60s) finish.

Over at my local super electric shop (100 mi away) I ran into a fellow flyer & he spoke of this kit and how he flew one and had a big impression on how well it could handle. "That plane can be a handfull".

Done w/ the landscaping. I'm gett'en too old for the amount of yard work this old motorcycle racer - aircraft mechanic. So time to t/o the internet radio & get 'er done.

Hey, pull that old Zlin out and dust her off compadre!
43851E is offline Find More Posts by 43851E
Reply With Quote
Old Jun 17, 2012, 10:29 PM
Registered User
43851E's Avatar
College Station, TX
Joined Jul 2009
882 Posts
After a long & productive weelend the retracts are done! I need to post a video and will give a quick tour on other items ongoing and even with the wing installed.

Completed in the last 2 days were the final wing fitting and the 2nd retract install. Late tonight finally the decision is made to go w/ the pull-pull system. 2 elevators also, so that is 4 wires & horns + 2 more for the rudder. Good thing about this is the bottom cable tubes will have both rudder & elevator cables together, 4 tubes in total. Also I will this time connect the cables before the servo as with my Gereral Hobbies Extra 300 brushless (very much modified) this was done at the servo & it works great, but it's just too much. May god help me if I drop the horn. Well that's the plan for now. I have to say that the P-51 style retracts using the new E-flite units work flawlessly...now. These were the 85 type where they open almost as far as the 90, so w/ the wing diheadral, their pointing straight down. As far as servo access goes, it will be from underneath the wing opening mounted inverted. Another thing about the pull-pull system, alighnment of the servos to the fuse exit is not as critical as with rods, but it will be spot on as if I were~ go figure.

Doug
43851E is offline Find More Posts by 43851E
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Found Nothing Park_Flyer Aircraft - Electric - Airplanes (FS/W) 7 Sep 06, 2012 04:09 PM
For Sale nadda Park_Flyer Aircraft - Fuel - Airplanes (FS/W) 2 Apr 15, 2012 02:14 PM
Sold Mint in Box Sig Zlin Akrobat $225.00 FREE SHIPPING! stevster Aircraft - Fuel - Airplanes (FS/W) 1 May 20, 2011 10:59 PM
Discussion Kit Zlin Akrobat z526 AS SIG Models LLego el motor Ayuda??? jcaramburu Mexico 29 Feb 18, 2008 11:22 AM