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RE: wingspan b-17 - 3/3/2008 2:23:36 AM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		getting that top tail fairing to smoothly flow is a little problematic thank good for filler. BTW that filler that they say is for balsa at the lhs can be found at meijer. Its called light and the can is red and white same stuff just not balasa colored. I can live with that since i have to glass the bird, Man if the wife would help.... on second thought ill do it myself she thinks glassing is buying glasses

(in reply to timothy thompson)
       Post #: 101

RE: wingspan b-17 - 3/4/2008 2:29:13 AM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		here are the tail and elev servos 98 oz rudder and 130oz elev. torque rods will actuate the surfaces all internally, I was told im overdoing the torque that 90 oz is good enough but im runnng 135 on elev one each side. if we get our big snow tomorrow i may have it all working, at least the tail anyway

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< Message edited by timothy thompson -- 3/4/2008 2:38:21 AM >

(in reply to summerwind)
       Post #: 102

RE: wingspan b-17 - 3/4/2008 5:47:13 AM   
wingspar


 

Posts: 148
Joined: 10/17/2003
From: Sammamish, WA,
Status: offline 		A 98 oz servo on the rudder?? Are you sure? Seems to small to me. You might want to run the calculations on servo torque needed.

Dave

(in reply to timothy thompson)
       Post #: 103

RE: wingspan b-17 - 3/4/2008 5:57:39 AM   
ram3500-RCU



Posts: 1655
Joined: 8/17/2002
From: n. canton, OH, USA
Status: offline
quote:

ORIGINAL: wingspar

A 98 oz servo on the rudder?? Are you sure? Seems to small to me. You might want to run the calculations on servo torque needed.

Dave

JR 8711 has just over 400oz I think. That would do it for sure, and you would have better centering.

< Message edited by ram3500-RCU -- 3/4/2008 5:58:54 AM >

(in reply to wingspar)
       Post #: 104

RE: wingspan b-17 - 3/4/2008 1:41:46 PM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		mike told me he ran 90 oz on all controls and she flew great. I was not believing it until I talked to mike. ailerons will have the very high torque servos your are talking about as will flaps. Each elevator is 132 each so thats ok. Remember she will fly like a bomber and as mike put it no sudden control movements as in aerobatics. I was going big on rudder till i talked to him.

(in reply to ram3500-RCU)
       Post #: 105

RE: wingspan b-17 - 3/4/2008 3:40:48 PM   
Scotsman


 

Posts: 72
Joined: 3/19/2004
From: Westford, MA, USA
Status: offline 		Tim,

Where do you plan on locating hatches to ge to the tail servos? You mentioned earlier that you were going to have a scale hatch to get to them, but all the 3-views I have seen don't show any hatches in that area of the fuselage. Your build looks great. I'm pretty sure you are the Eveready Bunny................

(in reply to timothy thompson)
       Post #: 106

RE: wingspan b-17 - 3/4/2008 4:37:32 PM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		i will have to make a compromise and make them. I must have servo access in that area so could be a patch or repair. There are things we must do to make these flyable. Now im worried about my rudder torque. what are your servo ratings? I went with mikes reccs. I will make 3 hatches one for each servo and make them look like access panels. Compromises must be made. Im not gluing the sheeting in hoping for years of trouble free use it is murphys law. I will try and get the torque rod done tonight for the rudder. I already glued the rod in the le of ther rudder and made her flush so you wont see any visible link at all

< Message edited by timothy thompson -- 3/4/2008 4:42:29 PM >

(in reply to Scotsman)
       Post #: 107

RE: wingspan b-17 - 3/4/2008 5:09:52 PM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		just got off the phone with mike he said 90 oz for the entire plane in his words you fly in a scale manner and do not 3-D the thing. Hes working on a hidden linkage for the ailerons. He said make the acess hatches and use rare earth mags to not have screws. flite metal and rivits will hide those hatches

(in reply to timothy thompson)
       Post #: 108

RE: wingspan b-17 - 3/5/2008 3:07:49 AM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		got the rudder done. Im using a old radio to actuate the servos as the jr 12 ch 2.4 isnt in till summer. i get 1 1/4 inches both ways

< Message edited by timothy thompson -- 3/5/2008 3:27:56 AM >

(in reply to timothy thompson)
       Post #: 109

RE: wingspan b-17 - 3/5/2008 3:16:26 AM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		well rudder is working nice mike said only 3/4 in needed i have 1.5 in each way. I guess a big bomber doesnt need large visible contol delections. when i fly my 172 i barely see any aileron deflection in turns so I think as Mike does that the 3-D movement has folks thinking we need tons of torque and ganged servos. We are not doing loops and rolls with a b-17.

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< Message edited by timothy thompson -- 3/5/2008 3:42:15 AM >

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       Post #: 110

RE: wingspan b-17 - 3/5/2008 1:26:49 PM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		i am running off a 4.8 v pack for tests so my torque will go up when i use a 6v pack. Im surprised how well the rudder self centers itself. My taylor corsair is a great flyer but the rudder always goes off to one side at neutral. once we get air flow its not an issue ive had 50 flights on that one and shes still nice Good positive control no slop on the b-17. I added two steering arm supports to keep it all slop free, took 30 min to add and really helped

< Message edited by timothy thompson -- 3/5/2008 4:55:56 PM >

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       Post #: 111

RE: wingspan b-17 - 3/5/2008 10:17:03 PM   
rt3232


 

Posts: 2157
Joined: 12/4/2004
From: hastings, MN, USA
Status: offline
Hi Tim

Great build,
But gotta question why not use captive ball links insted of cleves's I have had the fuel tubing come off in less than one season, and with those putiyy much barried just a thought

Bob T

(in reply to timothy thompson)
       Post #: 112

RE: wingspan b-17 - 3/5/2008 10:36:44 PM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		ive used the big 4-40s and not had a problem. she flys at 40-50 mph. for a big plane not too fast. going to work on tubes for the stab. I MAY CHANGE THEM LATER REMEBER IM JUST WORKING ON THE GEOMETRY NOW

< Message edited by timothy thompson -- 3/5/2008 10:49:21 PM >

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       Post #: 113

RE: wingspan b-17 - 3/5/2008 11:40:49 PM   
Scotsman


 

Posts: 72
Joined: 3/19/2004
From: Westford, MA, USA
Status: offline 		Tim,
How do you get the control system to work with the torque rod pivots being forward and off center of the hinge line? Maybe it is just the angle of the picture, but it seems like the torque rod wire is on the front of the rounded leading edge of the rudder and that it would have to be able to move side to side to stay attached to the rudder. Could you show some pictures of the rudder whe it is defelcted?

(in reply to timothy thompson)
       Post #: 114

RE: wingspan b-17 - 3/6/2008 1:56:23 AM   
timothy thompson


 

Posts: 2761
Joined: 6/19/2004
From: saginaw, MI, USA
Status: offline 		due to the central carbon fiber hinge pin i cant get the torque rod into the rudder any farther and closer to the hinge line, which would be better but the cf rod is in the way. The rudder is held by the two main hinge points one at the top and the pivot blocks at the bottom. The thin black tube is the pin. The systems works fine giving me plenty of throw. Mike says ill only need about 3/4 each way for scale flight and i have 1.5 inches. Remeber these things lumbered around and were not designed for steep banks or dives. The pilots manual puts specific limits on bank angles and dives.
It would be an easy fix to cut the rod a little and i could line up the torque rod. It works fine like this and if I ever have a problem i can fix it then.

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