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Royal B-17 Homemade Retracts (Pics)

Old 11-02-2010, 05:18 PM
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Default Royal B-17 Homemade Retracts (Pics)

Here' a couple of pics the B-17'sstarboard retract. These work great but need nearly 2" of travel to function. (I custom
made a large servo-arm). These were made by the 1st Owner /Builder, a Lt. Kyle Matthew VAQ-135.
I am the 3rd Owner/Builder and am about 80% finished with the Plane
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Old 11-02-2010, 08:51 PM
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Default RE: Royal B-17 Homemade Retracts (Pics)

If I was you, I would do a lot of load testing on that design before committing a finished aircraft to them. Doesn't look very strong for side loads, for starters. Just a friendly thought.
Old 11-03-2010, 01:03 AM
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Default RE: Royal B-17 Homemade Retracts (Pics)

I plan to reinforce the area where the strut connects at the block to give it
more strength. the other big issue is the cut-out area at the backof the
outer strut whre a set screw is used to keep the inner strut from swiveling.
this will need reinforcement as well(I'm working on this one).

If they can't cut it I plan to install robart mechanicals.
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Old 11-03-2010, 04:48 AM
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Default RE: Royal B-17 Homemade Retracts (Pics)

ORIGINAL: Multi-Engine Guy
These work great but need nearly 2'' of travel to function.
Would it be possible to connect the servo to a asymmetrical bellcrank such that a normal amount of servo arm movement, gets translated into the 2" of retract movement?
Old 11-03-2010, 09:44 AM
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Default RE: Royal B-17 Homemade Retracts (Pics)


ORIGINAL: Multi-Engine Guy

I plan to reinforce the area where the strut connects at the block to give it
more strength. the other big issue is the cut-out area at the back of the
outer strut whre a set screw is used to keep the inner strut from swiveling.
this will need reinforcement as well(I'm working on this one).

If they can't cut it I plan to install robart mechanicals.
I haven't looked at the Robart struts that would fit this model, but I suspect they would have a much larger trunnion at the top to give a more favorable distribution of loads out to the nacelle/wing structure. Give me some dimensions on the current strut, and I'll give you a rough estimate of the loads at the top pivot to consider.

* diameter of the tire;
* distance from the wheel axle to the top pivot (where the cotter pin is);
* diameter of the outer brass tube of the strut;
* estimated finished weight of model (I think ~12 LBS was typical for the Royal B-17)
Old 11-03-2010, 01:26 PM
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Default RE: Royal B-17 Homemade Retracts (Pics)

I thought about using an offset bellcrank, but instead went with a modified/lengthend servo arm, works great.

Thanks, Jon
Old 11-05-2010, 07:20 PM
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Default RE: Royal B-17 Homemade Retracts (Pics)

On rcscalebuilder.com I saw a guy use these in his royal b-17 http://www.dbproducts.com/store/sprt.htm

You will need a free account on rcscalebuilder heres the link to the build:
http://www.rcscalebuilder.com/forum/...250&PN=0&TPN=1
Old 11-07-2010, 12:45 PM
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Default RE: Royal B-17 Homemade Retracts (Pics)

I fly any and all,

Thanks for the info. I've always heard that the Dave Brown
retracts were superior to most others, and these sound like they're fairly sturdy.
I will definitely consider these. As for the Scale Builders website, I had no idea
that it existed....Way cool site. Well I've got to go get back under my rock now.


Jon
Old 11-10-2010, 07:10 PM
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Default RE: Royal B-17 Homemade Retracts (Pics)

gap-rcu
hey you really got me thinking.... I'v got a set of .60 size Robostruts in my workshop
that might work, they're the "straight" struts. I'll try to shoot you measurements tonight ,
sorry it took so long to reply , I've been pretty busy lately.



Thanks
Jon
Old 11-20-2010, 01:53 AM
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Default RE: Royal B-17 Homemade Retracts (Pics)

It doesn't look like the Robostruts are going to retro-fit into
homemade jobs. I will attempt to reinforce the area around the
set screw, I'm not exactly sure how, maybe JB weld another
layer of tubing over this area using the same cut-out dimensions.
or maybe just some jbweld, cut/shaped around this set-screw,
keeping the clearance tight to eliminate any slop.

The dave Brown retracts, or if I can afford them, the Century Jet
retracts, are sounding better all the time.
If anyone has any ideas on reinforcing the struts, please let me know!

Jon

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