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Author Topic: New Brodak Viking Build  (Read 4698 times)

Offline David_Ruff

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New Brodak Viking Build
« on: November 07, 2023, 02:56:11 AM »
First; I am by no means a great builder or flyer.  I just do this for a hobby. 
That said, I had built a Viking several years ago and this newer kit seems like a much different design.  That is probably good.
Some rookie questions follow.
First, the bellcrank installation seems backward.  The pushrod is connected on the inside (leadout side) of the wing. In other words, the leadouts cross over the pushrod.  Normally I see the opposite?  The pushrod seems to be interfering with the leadouts?
Second, the pushrod is split and is soldered with a collar connecting the two pieces.  Not my favorite setup.  I prefer a pushrod without a soldered connection.  I don't think a Tom Morris type of ball link/carbon fiber rod system will work as there is a bend in the pushrod system on Viking.
Is that soldered connection a problem? 
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Offline Dennis Toth

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Re: New Brodak Viking Build
« Reply #1 on: November 07, 2023, 07:52:22 AM »
Dave,
The bellcrank setup is for normal counterclockwise engine rotation to have the back lead as up to somewhat counter the yaw force in downward maneuvers. If you go electric and use the clockwise motor rotation you can install the bellcrank with the pushrod to the outboard side and get the same benefit but for upward maneuvers.

The solder joint should be OK if done with StayBrite solder, just clean the wire and joiner good and get lots of heat to the parts being joined to avoid a cold joint. You could reconfigure the pushrod to CF and adjust the location to use the ball links just work take some planning.

Best,    DennisT

Online Ken Culbertson

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Re: New Brodak Viking Build
« Reply #2 on: November 07, 2023, 09:39:52 AM »
Either bellcrank location will work.  The leadouts cross over the pushrod both locations, just more so with the inboard location.  I use ball links on all connections so it is not difficult to add a washer or two under the pushrod connection to get some extra clearance.  I would question why it is necessary to have a bent pushrod.  Many of the older designs, especially profiles put a "Z" bend to allow for adjustment and would put a keeper at about the midpoint.  It has been a while but I think the Viking had one to allow it to exit the fuselage near the stab and attached to an external flap horn.  I personally do not like that arrangement and would find a way to make that a straight shot, even if it meant moving the bellcrank outboard a bit to give you a better angle.  If you make sure that the bellcrank is centered relative to the elevator when you make the bend for the elevator horn to attach there is no need for ball links and you can use soldered connections like they did in the old days.  Just make sure you have an adjustable handle.  Without flaps, that will be your go-to adjustment for level flight.

Ken

Let me add one thing.  I never had a Viking but I did have several Zilches.  I think they are cousins.  Before you cover the bottom, clamp the elevator at neutral and see if you can bend the pushrod by working the controls strong enough to overcome a 50mph force on the elevator.  If it bends it will most likely be on "Up" control.  Put in some braces to stop it from bending but not so tight as to prevent you from moving it.  We all flew like this before ball links and CF pushrods so you will be fine.

Also this tickled my need for an OTS plane.  I found Dennis's thread on the Brodak "redesign" and noticed that it appears, from the pictures that the kit has a centered flap horn.  If that is the case, by all means use a CF pushrod.
« Last Edit: November 07, 2023, 10:20:07 AM by Ken Culbertson »
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Offline David_Ruff

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Re: New Brodak Viking Build
« Reply #3 on: November 07, 2023, 10:14:56 AM »
Ken

I am looking at the Tom Morris ball link/carbon rod method.  I agree with what you say about re-locating the crank a bit more to the inboard side and making a straight shot to the elevator horn.  It looks doable on the plans.  I have been laying out the hardware on the plan to check.  I am waiting for a 3.5 Morris bellcrank assy. 
The plan calls for the pushrod to exit the wing and be bent and then soldered to the rear pushrod piece.  Not a fan.
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Offline Jim Svitko

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Re: New Brodak Viking Build
« Reply #4 on: November 07, 2023, 12:54:53 PM »
David:

Are you planning on using the leadout method where the leadouts are inside a piece of brass tubing, which is bent to a teardrop shape, and then looped thru the bellcrank?  This method takes up more vertical space than I can accept.  It might make it more likely to have interference between the leadouts and the pushrod.

I use this method.  It might be overkill for what you need but it is a bit more compact and thus less chance of interference between components.

Offline David_Ruff

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Re: New Brodak Viking Build
« Reply #5 on: November 12, 2023, 04:41:42 AM »
Here is what I am doing with the Viking bellcrank and leadouts...

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Offline Dennis Toth

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Re: New Brodak Viking Build
« Reply #6 on: November 12, 2023, 07:15:40 AM »
Dave that looks fine if you keep the ship light with a 40, but if you are going with the high powered 60 I would go to a stronger bellcrank. The bushing method is very good don't solder them just wrap and OK to put heat shrink on (put the heat shrink onto the line before you start, don't ask how I learned this). Also, use a 4" bellcrank.

Best,     DennisT

Offline David_Ruff

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Re: New Brodak Viking Build
« Reply #7 on: November 12, 2023, 07:18:10 AM »
Interesting info on the bellcrank.  I do have the 4.5 inch bellcranks in stock.  I can do minor mods and fit it in. 
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Online Ken Culbertson

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Re: New Brodak Viking Build
« Reply #8 on: November 12, 2023, 08:47:13 AM »
Interesting info on the bellcrank.  I do have the 4.5 inch bellcranks in stock.  I can do minor mods and fit it in. 
I have found that optimal control speed is definitely a function of the age of the pilot.  I have toyed with the idea of going to a 4.5" or even 5" on my next plane so that I can go back to using a hardpoint handle and still do *level* level laps.  Did you mean "in Stock" to be your personal stash or for sale somewhere?

Ken
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Offline David_Ruff

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Re: New Brodak Viking Build
« Reply #9 on: November 12, 2023, 08:50:36 AM »
Ken.  I meant my personal stash.  I have three of the Tom Morris 4.5 inch assys.
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Online Ken Culbertson

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Re: New Brodak Viking Build
« Reply #10 on: November 12, 2023, 09:01:45 AM »
Ken.  I meant my personal stash.  I have three of the Tom Morris 4.5 inch assys.
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Offline Colin McRae

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Re: New Brodak Viking Build
« Reply #11 on: November 18, 2023, 04:56:57 PM »
First; I am by no means a great builder or flyer.  I just do this for a hobby. 
That said, I had built a Viking several years ago and this newer kit seems like a much different design.  That is probably good.
Some rookie questions follow.
First, the bellcrank installation seems backward.  The pushrod is connected on the inside (leadout side) of the wing. In other words, the leadouts cross over the pushrod.  Normally I see the opposite?  The pushrod seems to be interfering with the leadouts?
Second, the pushrod is split and is soldered with a collar connecting the two pieces.  Not my favorite setup.  I prefer a pushrod without a soldered connection.  I don't think a Tom Morris type of ball link/carbon fiber rod system will work as there is a bend in the pushrod system on Viking.
Is that soldered connection a problem?

David, I don't particularly like the pushrod solder coupling design either.

But on a couple of past model repairs where I did not want to cut into the wing, I did use a Brodak coupler, but I did a JB weld vs solder. To ensure it will not come apart, I took my Dremel cutting wheel and put some slight 'sawtooth' nicks on either end of the rods, plus on the coupler itself so the JB epoxy has something positive to grab. Just using sandpaper is not good enough to roughen the surfaces as the music wire is too hard of a material.


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