HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 27, 2012, 06:12 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
1,653 Posts
I agree with CN and AS on this. You should have more structure on an all moving stab. Most full scale aircraft with all moving stabs have at least two structural connection points with the first and second ribs. This makes it a simply supported beam with overhand which is easy to analyze structurally. For spindle placement, the axial aerodynamic center of the control surface is used. Below is what my group did in college that illustrates this. What determined your spindle location?
scatsob is offline Find More Posts by scatsob
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 27, 2012, 06:33 PM
Capt. Z
falcon5's Avatar
Tonopah, Nevada
Joined Dec 2004
2,540 Posts
Quote:
Originally Posted by scatsob View Post
What determined your spindle location?
If by spindle meaning the rod location in the stab, I used the line on the 3 view whitch measured exactly in the middle, then angled the rod just slightly so as to minimize the weight needed for balacing it. I found that changeing the angle the rod entered the stab made quite a bit of differance in the balance of the stab. Now of course after glassing the weight distribution changed a little but as it sits now looks to be not even an oz to balance them. Not sure this is the correct way of setting one up but ehh it seemed like a good idea at the time
falcon5 is offline Find More Posts by falcon5
Reply With Quote
Old Mar 27, 2012, 08:04 PM
Registered User
byrocat's Avatar
Aurora, Ontario, Canada
Joined Mar 2002
1,612 Posts
Quote:
Originally Posted by krypto71 View Post
Can I request an outdoor picture next to something like a car, to get some perspective of the size?
Personally, I'd go for the old-RCM-style cover shot: 1 hot car, 2 hot models...

Even unpainted, it turns my crank.
byrocat is offline Find More Posts by byrocat
Reply With Quote
Old Mar 27, 2012, 09:22 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
20,505 Posts
Quote:
Originally Posted by falcon5 View Post
Interesting. Well I could use my dremel to cut the slot to add a rib. I do plan to balance the stabs. The Hitec 7955's should be here tomorrow. Titanium gear 250 oz. tourqe one for each stab so I hope that will handle the load.

For the rib you mean to put that right at the 90 degree bend?? so the steel rod cant break out of the stab??
yes thats what i would do ,sort of like the above pic that was posted ..,i just looked at a F-4 sitting over here and they have a big triangled shaped 1/4" thick doubler on the stab right where the axle ends ,you were smart to bend the wire and bend it toward the LE .i would have done the same . the 2 ribs set up will keep the axle from breaking out of the stab.the glass on the stab will keep it from twisting and breaking .thats why i said way back to lay the glass 90 degrees and at 45 degrees ,the one layer 90 make it strong lengthwise,and the 45 cloth keeps the stab from twisting ,also putting the axle at the scale location was right to do also.c/n and i have done f-5,f-20 's so we know that works.i had my F-20's stabs balanced and we were pushing 140 -145 with no proplem and i just had hitec 65HB's on the stabs.granted it is way smaller but it sounds like you got a good strong servo coming.how far into the stab is the wire before the bend?
AIR SALLY is offline Find More Posts by AIR SALLY
Reply With Quote
Old Mar 27, 2012, 09:32 PM
Bypass Ratio = Infinity
scatsob's Avatar
United States, NC, Jacksonville
Joined Apr 2006
1,653 Posts
Along with what AS said, you should also sandwich the bent part of the wire in balsa or plywood up to the skin of the stab. Along with not wanting it to rip out, you don’t want it to break free and rotate. With it just imbedded in foam that as almost certainly going to happen. Again, very cool project with very fun design challenges.
scatsob is offline Find More Posts by scatsob
Reply With Quote
Old Mar 27, 2012, 09:46 PM
Capt. Z
falcon5's Avatar
Tonopah, Nevada
Joined Dec 2004
2,540 Posts
Sounds good Rodger, and thanks wingman for bringing this to my attention.

Rodger the rod goes into the stab 7" then bends another 1.5" The steel rod I think must have been designed for robotics and was case hardned in some way because I had a heck of time bending that sucker.It took a vice and several HARD hits with a hammer to get it to even budge.

I can see why you guys glass stuff, man that stab is super tough. I wouldn't have belived it just glass over bare foam could make such a strong thing. I changed the direction of the glass between layers also Rodger just like you said.

I will take my dremal and use a cutting wheel and cut the slit for the rib tomorrow. The end that butts up against the fuselage was getting a ply cap anyway so it would have something hard to ride against the thrust bearing so i will leave that part as is.
falcon5 is offline Find More Posts by falcon5
Reply With Quote
Old Mar 27, 2012, 10:33 PM
Tow Dog.
Pilatuspc12's Avatar
United States, CO, Hotchkiss
Joined Oct 2006
1,652 Posts
Good job, Andy. Perhaps consulting a Northrup T-38 repair manual might give some ideas for those stabs. Congratulations, it is a very beautiful looking airplane. If I wasn't married, I'd ask to go out with it!

Randy
Pilatuspc12 is offline Find More Posts by Pilatuspc12
Reply With Quote
Old Mar 27, 2012, 10:49 PM
Capt. Z
falcon5's Avatar
Tonopah, Nevada
Joined Dec 2004
2,540 Posts
Quote:
Originally Posted by Pilatuspc12 View Post
. If I wasn't married, I'd ask to go out with it!

Randy
For any possible courtship requests as the planes father I must ask what are your intentions. There will be chaperoned dates only, dancing must be done 2 feet apart no touching, I must meet your parents befor hand, and she must be home when the street lights come on.
falcon5 is offline Find More Posts by falcon5
Reply With Quote
Old Mar 27, 2012, 10:58 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
20,505 Posts
sounds like you got this figure out ...with all this help im sure this will all come together...you know Nut is sand bagging to see how yours does.
scats pic i think helps alot to see what going on in the typical flying stab...they are built really strong ...if you saw how big the axle was in most of them you would be suprized.
AIR SALLY is offline Find More Posts by AIR SALLY
Reply With Quote
Old Mar 27, 2012, 11:03 PM
Capt. Z
falcon5's Avatar
Tonopah, Nevada
Joined Dec 2004
2,540 Posts
Quote:
Originally Posted by AIR SALLY View Post
.you know Nut is sand bagging to see how yours does.
.
I am going to get mine built just to the point of ready for maiden then stop and wait until Nut is done and we are going to maiden both jets together..
falcon5 is offline Find More Posts by falcon5
Reply With Quote
Old Mar 28, 2012, 01:52 AM
Registered User
MaHö's Avatar
Deutschland, BW, Friedrichshafen
Joined Dec 2001
865 Posts
Hello Falcon, I also did the structure with a 90° pin and two rips.
There are really big forces on the two rips, I know from my BVM F16. One of my inner balsa rips was broken lengthwise because the wood structure was also lengthwise. I only thought of torque forces. Looks like it should have been vertical. There are also big shear forces on the surfaces so the wood cracked a little. No big problem, but I underestimated the forces.
On the wing I use glas reinforced parts.

Looking forward to two nice first flights

regards Martin
MaHö is offline Find More Posts by MaHö
Reply With Quote
Old Mar 28, 2012, 08:22 AM
DELTAS RULE
corsair nut's Avatar
tehachapi, CA
Joined Jan 2006
21,523 Posts
after looking at your pics, i hate to be the bearer of bad news. i think your pivot points are too far back. even when balanced, youll still have flutter issues....the stab is going to want to swap ends in air with the pivot that far back. id like to see it another 1"-1.5" farther forward. you can leave it as is, just know you may run into issues at high speed with flutter.

dont wait for me lol
corsair nut is online now Find More Posts by corsair nut
Reply With Quote
Old Mar 28, 2012, 08:55 AM
Tow Dog.
Pilatuspc12's Avatar
United States, CO, Hotchkiss
Joined Oct 2006
1,652 Posts
Quote:
Originally Posted by falcon5 View Post
For any possible courtship requests as the planes father I must ask what are your intentions. There will be chaperoned dates only, dancing must be done 2 feet apart no touching, I must meet your parents befor hand, and she must be home when the street lights come on.
Boy, those are some pretty tough regulations! I just wanted to kiss her and see what she smells like.
OK, on a serious note, if you could get the 3-views for the actual stab construction on the full size bird, that would be a good start for determining the actual pivot point and shaft diameter and pivot shaft reinforcement structure. I know you've already covered this, so I'm just reinforcing it some more!
Good Job sir, we are keenly watching how this movie is going to end.

Randy
Pilatuspc12 is offline Find More Posts by Pilatuspc12
Reply With Quote
Old Mar 28, 2012, 09:17 AM
Registered User
MaHö's Avatar
Deutschland, BW, Friedrichshafen
Joined Dec 2001
865 Posts
sorry links dead.
Have the file at home.

( http://members.aon.at/spunki/Drehachse_Pendelruder.xls )
http://www.rc-network.de/forum/showt...me-(download)-...

regards Martin
MaHö is offline Find More Posts by MaHö
Last edited by MaHö; Mar 28, 2012 at 09:26 AM. Reason: link dead
Reply With Quote
Old Mar 28, 2012, 09:19 AM
Fly it like you STOL it!
Keenan smith's Avatar
United Kingdom, London
Joined Dec 2010
6,823 Posts
Linki no worky!!
Keenan smith is offline Find More Posts by Keenan smith
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Cool Micro F-5/T-38 Parkflyer Build boingk Pusher Prop Jet Models 2 Oct 17, 2011 09:58 PM
Discussion I knew it wouldn't be long!!!!!!! Flightbox FPV Talk 8 Sep 29, 2011 05:17 PM
New Product 1/6 HETZER JAGDPANZER 38(t) Sd.Kfz. 138/2 r/c full metal BIG TANKS PLANT RC Tanks 0 Sep 28, 2011 02:38 PM
Sold Hangar Sale E-Flite P-38 rtf, GP Fokker, WM Miss America EP, Easyglider EZ T-38 ScaleBrad Aircraft - Electric - Airplanes (FS/W) 15 Jan 02, 2008 01:22 PM