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Old Feb 03, 2012, 09:10 PM
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glewis's Avatar
USA, FL, Tampa
Joined Jul 2002
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About the prop,
1:16 scale of a 99" prop would be only 6.18". Seems a bit small for a 45" span model. We'll see when I finally receive the plans.
A prop that size will give me the option of using this prop. http://www.v-eastonline.com/products...5x10-cm)-.html
165mm is actually 6.5". Close enough and it resembles the real deal!
Might as well hunt a power system while we wait for the plan....
Thinking 1500 or 1700Kv blue wonders.

Glenn

oops, the landing gear pics are back a page now...
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Old Feb 03, 2012, 11:27 PM
Dog is my co-pilot.
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United States, GA, Brooks
Joined Mar 2005
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It ssems that the piston in the pictures is already too compressed to act as a retracting mechanism.

There seems to be a fork on the oleo. If the fork pushes the oleo forward, the rear arms would swing the wheel into the well. I don't have any plans to check the geometry against, but I'll take a look.

Djm
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Old Feb 04, 2012, 02:28 AM
Mexia Izonfia
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Monticello, MN
Joined Oct 2003
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Quote:
Originally Posted by glewis View Post
Looking at the pics of the landing gear now I'm really confused....
Combo oleo strut and hydraulic cylinder?
Glenn
It looks to me like there's a jack-screw or hydraulic cylinder that pushes the strut forward to retract the gear, and there looks to be a stop that the jack-screw/cylinder would pull the strut against to lock the gear down. The jack-screw/cylinder would be the blue link on the attached sketch.
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Old Feb 04, 2012, 08:00 AM
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glewis's Avatar
USA, FL, Tampa
Joined Jul 2002
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Good catch Djm, I didn't notice how little travel there was left on the oleo. No way that small movement could retract the gear.

Metro, that has to be the way it works!
I thought about that fork being a liner actuator of some sort the as you described but couldn't see how the oleo would pivot at the top. Must be just a big pin or something at the top end of the strut that is hidden in the pics.Sure looks like a tight fit into that stop block too.

Thanks for the input guys, it makes sense now.
That geometry almost looks like something that could be actuated with a servo...hummm.

One week and counting on the plan..
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Old Feb 04, 2012, 01:06 PM
It flew once before...
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Northwood , New Hampshire
Joined Jul 2004
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One week and counting on the plan..
I know what you mean Glenn ...They are not the fastest on delivery Got a few of their plans in the stash
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Old Feb 07, 2012, 01:23 PM
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glewis's Avatar
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Received an email from Cleveland. The plans finally shipped!
So a few days for the USPS to do their thing and hopefully I'll get a non-mangled package.
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Old Feb 09, 2012, 08:09 PM
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OK, finally got the plans! They were worth the wait too.
Shown on the plan is a clever retract mechanism that I might try to duplicate. It uses a torque rod and pulls the main gear leg up and to the rear.

The plans are a bit vague in spots and complicated in others and will take some studying before beginning to cut parts.

Speaking of cutting parts, the fuselage formers are made out of up to 5 separate pieces with the grain orientated around the perimeter. This makes for a very strong and light former. Problem is the 5 parts make only one half former! Yikes!
Plus scale rib spacing is shown and there's only 42 ribs,,, per side!

Places were the info is sparse are cowl construction and there are no patterns for the tail surface ribs. how to do the cabin windows is a puzzle too.

The calculated scale prop size is 6.2", and that is exactly the size shown on the plan.This means I can use the Graupner 6.5" x 4" semi-scale props and spin them with 1700kv blue wonder motors.
Performance figures from Heads Up RC show the 1700 with a 6x4 APC speed 400 prop on 3 cells will generate 12.5oz of thrust while drawing 7.5A with a pitch speed of 53MPH! That'll work! Guessing half throttle cruise will be possible.

First I need to get a copy made of the plan to cut up for patterns and construction can commence! Hope I don't get a hassle from Staples due to the copyright notices on the plan.

Glenn
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Old Feb 09, 2012, 09:34 PM
a.k.a. skcope
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Trumbull, CT
Joined Feb 2007
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Great looking plans Glenn! I wish I had thought of the torque tube arrangement for the landing gear. There was a control line DeHavilland Comet published in Model Aviation in the 70's which had an arrangement like you describe where a jackscrew in the fuselage turned the torque tube which actuated the landing gear in the nacelles. I will see if I can find the plan and post it. I remember being impressed by this mechanism and though it would also work well in a DC-3 or any aircraft whose landing gear retracted similarly (Like the Stinson Model A).
-Scott
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Old Feb 09, 2012, 10:15 PM
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Hi Scott, please post the details on that landing gear. It might be a better solution.
Here's a bit more detail of the retract system. Looks like it just might work.
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Old Feb 09, 2012, 10:50 PM
a.k.a. skcope
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Trumbull, CT
Joined Feb 2007
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Here's a scan of the DH Comet plan. The geometry of the system designed by this gentleman Ernie Violett is pretty brilliant. Obviously, it is very overbuilt for our purposes and would need to be scaled down (since we are not building control line "lead sleds" like they did in 1975) but the basic principles are there. If you need a more detailed file Glenn, let me know and I'll email it to you.
-Scott
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Old Feb 09, 2012, 11:37 PM
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Quote:
Originally Posted by glewis View Post
OK, finally got the plans! They were worth the wait too.
Shown on the plan is a clever retract mechanism that I might try to duplicate. It uses a torque rod and pulls the main gear leg up and to the rear.

The plans are a bit vague in spots and complicated in others and will take some studying before beginning to cut parts.

Speaking of cutting parts, the fuselage formers are made out of up to 5 separate pieces with the grain orientated around the perimeter. This makes for a very strong and light former. Problem is the 5 parts make only one half former! Yikes!
Plus scale rib spacing is shown and there's only 42 ribs,,, per side!

Places were the info is sparse are cowl construction and there are no patterns for the tail surface ribs. how to do the cabin windows is a puzzle too........
Cleveland plans in the "silver" series and up seem to be more about building an accurate static display model than a flying one. Too beefy for rubber power but not stressed properly for IC power either. You should feel free to modify as you see fit for weight and strength considerations as well as ease of building.

They are wonderful plans to look at and study however. The couple I have were beautifully drafted.
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Old Feb 10, 2012, 12:11 AM
It must have a machinegun
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Perth, Western Australia
Joined Sep 2004
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That's a worry if its not strong enough for flight. You might need to look closely at the wing spar design.
That's got to be the most crowded plan I've ever seen.
It it were me I would leave out every second rib. Not just to save work but to save weight. There could be as much balsa as a fully sheeted wing in that design.
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Old Feb 10, 2012, 12:47 AM
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United States, CA, Garden Grove
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Interesting and challenging build, especially in this smallish size. Same old compromises , build it light as practical for reasonable stall speed, pleasurable flying, and minimum landing damage, etc. yet try to make it look as scale as practical. Decisions,decisions.
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Old Feb 10, 2012, 10:07 AM
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Rockford Illinois
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That's a really complex retract system. Get that to work and we can start scratching your name into the plaque =)
I agree with the other comments, cutting every rib might make this thing far too heavy.
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Old Feb 10, 2012, 12:09 PM
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Thanks Scott.
Man, that system is built like a tank but looks like it would work well. I'll goof around with the one shown on my plan first and if I can't get it to work I'll have a backup plan.

Pmullen, these are platinum series plans. This one was designed for rubber power but you're right, it's a bit on the beefy side. I would have to eliminate some weight before attempting to rubber power it.

Scaledown, I think I'll make a composite outter wing panel spar out of 1/32" ply skins on a 1/16" balsa core. I have found this system is stronger than bass or spruce and lighter than birch ply. The center section spar will be 1/8" birch ply for the additional strength. As much as I like the scale rib spacing there is just too much lumber involved so to save weight only every other rib will be used. Another reason is the plan only has patterns for the even number ribs....

E-C. Yep, as always compromises have to be made for lightness and strength.
The plan shows cabin floors and seats. I might have to leave some of those details off. With nearly 40oz of thrust@50+ mph pitch speed I might have a little room in the weight budget for some decent detail. Would be cool to have a cabin full of passengers....

Dan, I could go with 1/32" sheet ribs and still use the scale spacing.
NOT! been there done that.
Used 1/32 ribs on my Laird and found out ribs that thin will break if you look at them funny. Just picking the wings up resulted in that unmistakable crack sound followed by some choice words and reaching for the ca....

Thinking more about the ribs, the model is 1:16 scale. Using 1/16" wood translates to a full scale rib thickness of 1". Wonder how thick the full scale ribs are?

Just ordered 3 1700kv blue wonder style motors and esc's from Heads Up RC.
Also ordered the semi-scale props from Graupner USA. 24 bucks for 4 props which is ok, but then add 12 bucks for shipping!
Sheesh, I could almost have drove down to Sarasota and picked them up in person for less than that in gas....
I hate UPS....It will only take them 5 days to deliver from 60 miles away, what a deal for 12 bucks...
Heads up charges 2 bucks to ship USPS and I get stuff in two or three days.

Glenn
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