jrCessna O-1 Bird Dog (Intermediate Build Trainer)

[JohnRambozo]

Its time to scratch build again!

This high-wing trainer is going to be easy to build (easy side of intermediate) and hopefully very easy to fly. I am designing and building it so that I can teach my dad (age 70) and my son (age 17) to fly R/C this spring and summer.

Neither one have any experience with R/C so I'm thinking the jrH-1 may be a little fast for them to handle. I'm expecting a nice, slow floater.

First a little background: Wikipedia entry on the Cessna O-1 Bird Dog.

3-View

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Specs:
Fuselage: 29 inches
Wingspan: 42.5 inches
Electronics: 4 servos (5 for flaps)
Motor: BEEF (Park 425 equiv)
Prop: 9x4.5 SF
Battery: 3S 2200 mAh

I was able to get the adjustments made to the wings. In order to fit everything on 2 sheets of foamboard, I split the wings with a center section that will have some paper overlap for added strength.

The updated plans are here. I will likely be waiting until I have some of the new water resistant foam before I begin building version 2.5.

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jrCessna O-1 Swappable Bird Dog v2.5 Plans (PDF):
jrCessna-O-1v2.5_1of2.pdf
jrCessna-O-1v2.5_2of2.pdf

2.5 Plans Updated with the following:
Organized to fit on 2 - 20x30 DTFB Sheets
Added nose formers
Added duplicate of internal fuse former
Labeled that odd-shaped guide you were wondering about
Added Tile Marks for 7.5 x 10 tiling

Windshields and Nose Posterboard cover:
jrCessnaBirdDog_Windshields.pdf
jrCessnaBirdDog_Nose_Poster.pdf


If anyone attempts to build this before I do, please let me know and I'll be happy to help clarify since I didn't indicate what to do in some areas. (such as removing paper or foam)

Paxbot is doing a great job building v2 here. (2.5 is the same design, just update plans for ease of use)

Photos / text below are for v1.

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I've designed some nice ARMY emblems to go with this plane for those that want them. They are scaled to print on one page. You'll need 2 pages of lettering and one of the stars.

Links here:
ARMY Lettering for jrBirdDog.
ARMY Star Emblems for jrBirdDog.

Latest Progress as of 3/12/15:



Final (without LG)

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[twodogs]

This is the one I've been waiting for.

 

[ClearSkiesCalmWinds]

Looks good. I'll be following this one. A good trainer is always worth the wait.

 

[rcspaceflight]

I love the Birddog. Looking good!

 

[Tench745]

I can't wait to see the result. Your top-portion of the fuselage looks like it's missing the window sections.

 

[BanditJacksRC]

Looks like its coming along great. What did you use to make the plans?

 

[abieex]

Looks great, I'll follow along.

 

[rcspaceflight]

I have a question: Are you going to angle the fuselage more at a "V" angle like the real plane? Or is the fuselage going to be a box just to keep it simple? (When looking at the plane from the front view.)

 

[Joker 53150]

I like your subject choice, and recently did the L-19 version in balsa. It's a light design, fun to take out on a calm day.

 

[JohnRambozo]

I can't wait to see the result. Your top-portion of the fuselage looks like it's missing the window sections.

You are correct there, Tench. I am intentionally sacrificing some scale details to keep the build process simple. If there is an uproar from the community, I'll make alternate fuse plans that account for the cockpit that widens as it goes up.

 

[JohnRambozo]

This is the one I've been waiting for.

Looks good. I'll be following this one. A good trainer is always worth the wait.

I love the Birddog. Looking good!

Thanks guys. I'm glad to see so much interest right out of the gate. Now the pressure is on.

 

[JohnRambozo]

Looks like its coming along great. What did you use to make the plans?

Thanks. I'm using the Open Source variant of photoshop - GIMP to more or less trace the 3-view. Nerdnic demonstrates the technique in his series How to Design DTFB Planes. He uses photoshop. I use the pen (vector) tool in GIMP. I can go into more specific detail about how its done in GIMP vs. Photoshop if you'd like.

 

[JohnRambozo]

I have a question: Are you going to angle the fuselage more at a "V" angle like the real plane? Or is the fuselage going to be a box just to keep it simple? (When looking at the plane from the front view.)

That's something that is going to be determined by the motor. I'm intending to angle the nose down as much as I can before the motor sticks out of the top. It will certainly be less boxy than you see it now. The front section is going to be handled much like the FT Storch.

Woops. I answered this thinking you meant the angle of the nose in profile view.

Actual answer to your question:
I started out intending to keep it extremely simple but from the instant response I've gotten, I better step it up and go for more scale details. It will be easy enough to make the adjustments and will give more 'meat' for the power pod to hold onto.

 

[ClearSkiesCalmWinds]

IMHO the fun is in the details. At least the ones we can replicate to make it repeatable. Looking forward to seeing this "Bird" develope.

 

[JohnRambozo]

I like your subject choice, and recently did the L-19 version in balsa. It's a light design, fun to take out on a calm day.

Thanks for sharing your build log of the balsa version. That's a great looking plane. I love the olive drab. Short take off, for sure.

 

[JohnRambozo]

IMHO the fun is in the details. At least the ones we can replicate to make it repeatable. Looking forward to seeing this "Bird" develope.

I have a feeling I've already been talked into changing the fuse shape to be more scale.

 

[ClearSkiesCalmWinds]

Very cool!

 

[twodogs]

The scale shape of the fuselage would be nice but , may make it more difficult to build for beginners. I've been looking at this plan to make someday (when I learn how to fly again) http://www.outerzone.co.uk/plan_details.asp?ID=5905 although scaled down some.

now you have my 1st and 2nd posts.

Brad

 

[JohnRambozo]

The scale shape of the fuselage would be nice but , may make it more difficult to build for beginners. I've been looking at this plan to make someday (when I learn how to fly again) http://www.outerzone.co.uk/plan_details.asp?ID=5905 although scaled down some.

now you have my 1st and 2nd posts.

Brad

Cool. Thanks for sharing those plans. There are shapes for the front and rear windshields and they show the proper CG point. That will save me some experimentation.

I'm going to do the angled fuse and include an outside angle guide to use during assembly as well as formers for support inside the fuse.

I'm working out the formers now.

 

[twodogs]

Can't wait. hehe

Brad