1/3 Scale Cherokee - RC Groups
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May 13, 2010, 11:25 PM
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Seadog's Avatar
Build Log

1/3 Scale Cherokee


All,

I've sat on this for a bit but have made enough progress to start sharing my build of a 1/3 scale Cherokee. I based it on my original 1/4 scale plans but have made some changes, primarily for additional strength at the larger size, but also hopefully to improve the performance a bit.

The performance change has been to change the airfoil from the original GO549 to the HQ3514. This change was made before the recent discussion on RC Groups about the flying qualities of this airfoil, so hopefully I have lucked out.

The general construction is the same, with a few details changed which I will describe during the build log. The truss is still made of balsa, in this case 5/16" sq. hard balsa, which is 50% bigger in cross section than the 1/4 sq. that was used in the smaller version. I can tell you that the fuselage is very strong and that I have no concerns whatsoever about using balsa for the truss.

I have changed the rudder build slightly as the original tended to warp and was a bit fragile. With luck this one will keep its form and be tougher to boot.

Just FYI, I used blade and box because that is what I had available in my workshop, but steel or carbon rod would work as well. The joiner is made of two blades/boxes. The top one is 14mm wide and extends 8" into the wing. The lower one is 12mm wide and extends 4".

Here are the "catch-up" pictures. From this point onwards the build will be in real time, and as I have a bunch of travel in the next few months it may be slow.

I am willing to share my plans, but be aware that this version is untested and generally speaking I would prefer to build the prototype and make sure it flies well and is robust before turning it loose. Your call....

As there are already a number of Cherokee builds posted here, I won't go into great detail; just posting the interesting bits.

Dave Smith
Last edited by Seadog; May 13, 2010 at 11:27 PM. Reason: typo
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May 14, 2010, 05:18 AM
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Dave - looks like the real thing! Very cool I look forward to following along.
May 14, 2010, 07:59 AM
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Dave

... great. I have also been thinking about a bigger version every now and then...
Considering the flight characteristics of the 1/4-scale version, i would not have the least doubt about this one.

Have fun - I shall watch your progress!

Herbert
May 14, 2010, 10:50 AM
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Looks good. Interested in a set of plans when you get done.

Scott
May 14, 2010, 02:47 PM
Nothing like a good WOODIE!
cooper998's Avatar
Dave,
As you know I have been dreaming of a 1/3 scale Cherokee for some time now. My 1/4 scale is a dream to fly and I know 1/3 can only be better. I even have the paint scheme already planned... just need some plans and I can start cutting wood

Tony
May 14, 2010, 08:15 PM
Registered User
Tony I have the plans ready that Dave sent Me , I will get You a copy
I was down the shop today looking at what was printed out
Had to make some scale adjustments to the size and how the were printed
They are printing new sets of the body Monday
May 14, 2010, 09:11 PM
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Lbuff1's Avatar
Herbert, rumor has it you are coming to the East Coast next month, looking forward to seeing you here. Nice Plane Dave, I have a friend building the smaller one. I'll let him know there is a bigger one in the pipeline.


len
May 15, 2010, 09:04 AM
Registered User
Hi Len,

the rumor is right: 12th of June is the date! After our little grand-daughter`s birthday celebration, I am looking forward to meeting some of you folks - Steve(R), the weather and other good vibrations permitting... :-DDD

@ Dave,

is there already an up-scaled plan? Or laser-cut data/parts?
On the other hand, two meters twenty for the fuselage are already touching the limits of my facilities...

Herbert
May 15, 2010, 09:32 AM
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Seadog's Avatar

Plans


Herbert,

As I mentioned in the first post, there are plans that I am willing to share, but they are a work in process and have to be updated to reflect the "as-built" version, since I am making some slight modifications during building for strength, plus finding out where some parts don't fit as well as I expected .

Of course most of the changes are in the fuselage; the wings are pretty straightforward and difficult to go too far wrong. The HQ airfoil puts the high point behind the main fuselage former as you can see in the pictures, and the sheeting is now 3/32" instead of 1/16", but if you were to create some ribs using Compufoil or Profili, you could start the wings while waiting for the fuselage drawings to be completed. With those airfoil programs you could adjust the wood sizes to match the metric stock that you would be using, and the changes at the fuselage would be small.

So, yes, I can share the plans now, but I don't want any complaints if things don't fit perfectly or some part isn't as strong as you think it should be. Once the plane is built I will refine the plans and they will be more suitable to create cut files from, plus we will know if it flies like an angel or a pig!

David
May 15, 2010, 07:44 PM
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Seadog's Avatar

Progress


Center section sheeted, and some turtledeck formers added. No glue yet for the formers as I'm working on the alignment. The turtledeck goes from an elliptical form at the wing to a triangular form at the stabilizer, and all the stringers have to lay nicely on the formers or you get a pretty wavy outcome, so that's what I'm playing with now.

The backbone of the stringers is 1/8" x 3/8" here. On the 1/4 scale model it was 1/8" x 1/4". This adds a bit of strength, although the turtledeck is fundamentally a streamlining form and generally speaking, the loads are carried by the truss, so the turtledeck only has to able to manage handling loads.

Dave Smith
May 16, 2010, 05:05 AM
Registered User
Thanks, Dave,

that was a question - there is no hurry as I still have two "wooden projects" on my bench...
But I am following closely with great interest!

Herbert
Jul 01, 2010, 09:58 PM
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Seadog's Avatar

Back in Action


I was out of country for most of June, just returning last Wednesday, but have started up again and made a bit of progress. The turtledeck stringers are in place, as well as the nose keel. Next steps are the wheel mount and the lower formers; then on to the stab mount and the stabilizer. The side stringers will pretty much finish up the fuselage. After that the wing, canopy and covering, and go flying. It all seems so simple, doesn't it?

Dave Smith
Jul 02, 2010, 07:31 AM
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SZD16's Avatar
Very nice!
Sep 04, 2010, 07:54 PM
Registered User
Hey Dave , Former H's slot does not go deep enough on the plan
Did You cut it deeper down the former or did you slot he rib?

CR


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