HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 01, 2012, 08:55 PM
Registered User
cityevader's Avatar
United States, CA, San Jose
Joined Mar 2012
2,882 Posts
Quote:
Originally Posted by plane_tech View Post
I would bed to differ on this point. The joiner should be tight enough that it can not slide apart on its own, but loose enough that an excessive amount of force is not needed to separate it.
The bolts should be tight enough not to allow movement in any direction, axial, rotational, or in shear. If you want to prevent the bolt from zippering the wing as it did, cut a length of brass or aluminum tubing with an I.d. close to the o.d. of the threads and place that in the wing. Making sure it is bonded throughly.
On the next less than ideal landing, the bolt will shear at the end of the tubing instead of through the sheeting.
Also, if you happen the over tighten the bolt, the tubing will prevent the wing from crushing.
Just my $0.02
Where to start...first, I'm disappointed the nylon bolts didn't break sooner. I always cross-drill all my wing bolts with a 1/16" bit. Sometimes in an "x" pattern, sometimes in a "+" pattern depending on my level of whimsy at the moment.
Tensile strength of two nylon bolts far exceeds the breaking point of this particular wing, so I design in a shear point...didn't work.
There is a bit of aluminum tubing supplied with the kit that prevents overtorquing and wing-crush...the aluminum "bushing" gets compressed before the wing itself to prevent sheeting damage. In retrospect, that is only half of its job. It should have also been incorporated into the wing structure itself...or at a very minimum, the wing should have had more than a balsa root rib through which the bolt passed.
Regardless, if I had not taped the wings together, it would have merely rotated like every other landing. upon impact, the wings rotate against the two bolts, and spreads apart about 2" and alleviates most of the load, or at least allows rotation to the point that by the time it reaches a critical angle the obstacle has passed and/or the fuse has rotated also, thereby reducing further stress. Picture below shows typical separation with zero tape with no damage from mildly "off-center" landing.
During flight there is no load that pulls the wings apart, so tape unnecessary in-flight.

Funny thing is, I was planning on doing some fiberglass reinforcing to the root but with another day left in my free weekend, I decided to fly a second day. (The dreaded "one last flight" syndrome?) But I was so thoroughly enjoying myself in the amazing near-sunset-lighting (despite the weak lift) that I just kept going...and of course lost it in the low sun!! So now I'll do the solid-block-in-wing for the bolts, and glass the entire leading edge sheeting and layer it at the root.
cityevader is offline Find More Posts by cityevader
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 01, 2012, 09:53 PM
Theoretical Modeler..
plane_tech's Avatar
Joined Oct 2007
2,168 Posts
Quote:
Originally Posted by cityevader View Post
Where to start...first, I'm disappointed the nylon bolts didn't break sooner. I always cross-drill all my wing bolts with a 1/16" bit. Sometimes in an "x" pattern, sometimes in a "+" pattern depending on my level of whimsy at the moment.
Tensile strength of two nylon bolts far exceeds the breaking point of this particular wing, so I design in a shear point...didn't work.
There is a bit of aluminum tubing supplied with the kit that prevents overtorquing and wing-crush...the aluminum "bushing" gets compressed before the wing itself to prevent sheeting damage. In retrospect, that is only half of its job. It should have also been incorporated into the wing structure itself...or at a very minimum, the wing should have had more than a balsa root rib through which the bolt passed...
The fg'd joint and the solid mounting in the root was presumed... not assumed as we all know what that comprises..

I personally don't like the idea of the break away bolts. I have had a wing or two depart in flight do to over zealous flying nylon bolts shearing. Granted it was a 40 size plane with a 55ax on a spot on tuned pipe with cleaned up exhaust and intake ports, running a custom 20% nitro blend and a 10x9 prop at 19k static on my test stand.

I have also had the wing mounts, that were 0.063 aluminum and fiberglassed into the fuse ripped out before with wing bolts sheared.

Maybe this is why I switched to a more solid mount in the fuse and smaller (4-40 or 6-32) steel bolts for the wings instead of the 1/4-20 or 1/4-28 nylon bolts as is the standard that I see with BARF's. Just me, but I find it easier to repair/rebuild a fuse than to rebuilt/repair a wing while keeping the airfoil accurate, the lateral balance even and the structural integrity in tact.

again... just my hay-penny's worth...
plane_tech is online now Find More Posts by plane_tech
Reply With Quote
Old Oct 01, 2012, 10:03 PM
Registered User
cityevader's Avatar
United States, CA, San Jose
Joined Mar 2012
2,882 Posts
Music!!!
In a DS thread involving the "Scratcho", I was captivated my the music, which is kinda hard to come by. Turns out it's his (or someone's) daughter's band. Turns out there's a site called bandcamp.com that caters to artists.
Now i'm captivated with this site, perusing artists until I find something I like (extremely difficult since I'm so picky!!) and purchasing tracks I like.

Just thought I'd throw it out there...there's a huge ocean of artists that aren't in the top 40 because the big wigs suck...but that doesn't detract from their artistry!! So if you take a little time and find something you like, buy it!
cityevader is offline Find More Posts by cityevader
Reply With Quote
Old Oct 01, 2012, 10:13 PM
Registered User
cityevader's Avatar
United States, CA, San Jose
Joined Mar 2012
2,882 Posts
hey now, did you just make an asss out of you and me?!?!

For what it's worth, my Speedo tops outs at 385g without ballast. Not much load on two wing bolts.

As for fuse repair vs wing repair...I don't want to do either!! But I think a 2" wing repair on either side of the center line prolly won't give up too much performance even if the foil section is botched.

If I can get just the right combination of strength to designed-in-failure, I'm all over that!!

I believe, if the wing was "properly" designed with a sturdy retention block/wing connection, the bolt would have properly sheared, and I could have flown again... the newly repaired wing WILL be such!
cityevader is offline Find More Posts by cityevader
Reply With Quote
Old Oct 01, 2012, 10:30 PM
Theoretical Modeler..
plane_tech's Avatar
Joined Oct 2007
2,168 Posts
Wish you luck.. I have been designing/redesigning/redesigning/redesigning my wing retention system for the 2.75m I am currently working on...
plane_tech is online now Find More Posts by plane_tech
Reply With Quote
Old Oct 01, 2012, 10:35 PM
Ultrabatics enthusiast
Diceman89's Avatar
United States, CA, San Jose
Joined Aug 2012
939 Posts
Good, learn, remember, and then do it to mine! Ha Ha!!

I really want to put a way bigger elevator and add a rudder to my speedo. Kinda boring to fly. It flys well yes, just limited.
Diceman89 is offline Find More Posts by Diceman89
RCG Plus Member
Old Oct 01, 2012, 10:49 PM
Registered User
cityevader's Avatar
United States, CA, San Jose
Joined Mar 2012
2,882 Posts
hmm...when I strip off the covering to do repairs, maybe i'll do some mods as well. Granted, I haven't read the Speedo thread, as there is likely a similar post...but perhaps I'll change it to full span ailerons...or perhaps flaps/ailerons programmed together, or even WIDER surfaces!. Heck, since I'll be opening it up, may as well mod!!
cityevader is offline Find More Posts by cityevader
Reply With Quote
Old Oct 01, 2012, 11:56 PM
Ultrabatics enthusiast
Diceman89's Avatar
United States, CA, San Jose
Joined Aug 2012
939 Posts
You go boy !
Diceman89 is offline Find More Posts by Diceman89
RCG Plus Member
Old Oct 02, 2012, 01:13 AM
The original Flying Pigs Sqd.
Up&Away's Avatar
Netanya, Israel
Joined Aug 2002
10,025 Posts
Quote:
Originally Posted by cityevader View Post
...but perhaps I'll change it to full span ailerons...or perhaps flaps/ailerons programmed together...
I don't know what profile the wing is, but not all wing profiles benefit from full span ailerons, or even flaps/ailerons. Check the Speedo threads first. If it is doable, I'm sure someone's done it by now.
Up&Away is offline Find More Posts by Up&Away
Reply With Quote
Old Oct 02, 2012, 01:52 AM
find me @samotage
samotage's Avatar
Melbourne Australia
Joined Jul 2005
8,362 Posts
ZOMG! This thread is still alive!
samotage is offline Find More Posts by samotage
Reply With Quote
Old Oct 02, 2012, 02:21 AM
The original Flying Pigs Sqd.
Up&Away's Avatar
Netanya, Israel
Joined Aug 2002
10,025 Posts
Quote:
Originally Posted by samotage View Post
ZOMG! This thread is still alive!
Hasn't even been ill once!
Up&Away is offline Find More Posts by Up&Away
Reply With Quote
Old Oct 02, 2012, 02:34 AM
find me @samotage
samotage's Avatar
Melbourne Australia
Joined Jul 2005
8,362 Posts
Quote:
Originally Posted by Up&Away View Post
Hasn't even been ill once!
brick*
samotage is offline Find More Posts by samotage
Reply With Quote
Old Oct 02, 2012, 03:02 AM
Egads! It's a GIRL!
Lil Stinkpot's Avatar
United States, CA, San Jose
Joined Jul 2011
3,321 Posts
Quote:
Originally Posted by Up&Away View Post
Hasn't even been ill once!
No, but it has been infiltrated by an alien species.
Lil Stinkpot is offline Find More Posts by Lil Stinkpot
Reply With Quote
Old Oct 02, 2012, 03:08 AM
The original Flying Pigs Sqd.
Up&Away's Avatar
Netanya, Israel
Joined Aug 2002
10,025 Posts
Shhh...!


Otherwise they'll all want a green man at home to do the cleaning...
Up&Away is offline Find More Posts by Up&Away
Reply With Quote
Old Oct 02, 2012, 11:54 PM
Torn 'twixt buildin' and flyin
TheNightowl's Avatar
United States, TX, Austin
Joined Oct 2007
7,188 Posts
Page 2 rescue!

Slackers!
TheNightowl is offline Find More Posts by TheNightowl
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Whoops! Sorry, error, please delete MterBeest Slope 15840 Jun 25, 2010 10:06 AM
Mini-Review Sorry please delete this dup Crushalot Coaxial Helicopters 0 Oct 21, 2009 12:31 AM
Discussion SORRY! Unintened thread - please delete! VTOLicious Coaxial Helicopters 0 Oct 05, 2009 04:18 PM