Stearman PT-17 Laser Cut Kit Build Continued

[davidchoate]

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Last winter I was given a Laser PT-17 kit to build and check for imperfections before production. I have been pitting off final assembly because Guillows has no sure way of aligning the wings "perfectly". So I decided to practice on a Walnut scale Dumas Hawk, and I believe that their method is what I will do. I need to make a couple jigs for alignment though. Oh, and its a RC conversion as well

[davidchoate]

It weighs 50 grams now with motor and brick. probably 10-15g more for a battery. A Guikkows plane of that size would be around 80-90 gramsAUW. The Contest Balse makes a lot of difference3. And if and David Lewis types read this, can you please help Me with where to set thhings. Decolage, Balance, etc. It was a rubber motor kit, and I bet it would Fly nice on Rubber. Very light.

[davidchoate]

pt17

[NcGunny]

Are the areas that are black in the second pic all infilled? It looks like it from the 1st pic, I was wondering what the top part behind the headrest is made from. I made that long tear drop part from a dowel once,it was supposed to be balsa but I figured all the strips would turn into a mess. Good looking covering job also on it.

[davidchoate]

The headrest was plastic. The cowl, and oill cooler? scoop( which will make a perfect battery holder) were plastic. I did infill forward of the cockpit to add strength to where the cabanes attach. I usually infill a little on micro RC just to add strength. I am amazed at how light She is.

[davidchoate]

0K. I have been doing My best to keep up with learning more about biplanes in order to finish My Stearman I started last Jan. I learned alot from the little Walnut scale Hawk, and it was cheap. Unexpectedly I learned how to make balsa Wheel Pants. I have just finished a big project, and now have time to dedicate to The PT-17. RC conversions. I first will be cutting off the CA Hinges I used, and replace them with micro-pin hinges. There is just no comparison between the two. I do not know why it took so long for Me to discover them.

[NcGunny]

Nice Pants Dave! Mine are made almost the same way as you made them. Stuka is a little different construction for me. I have yet to find a decent way to bend the wire once its inserted thru wheel and pant that doesnt harm the pants bending it. I always found the Stearman to be a odd plane..if top wing was removed it would almost look like thats its natural flying look,add the top wing and it still looks normal.

[davidchoate]

I used the wood strut that goes over the wire LG and glued it in to a slot I made in the wheel pant. I just trimmed the wire so it did not protrude through the outside.

[davidchoate]

The Dumas Hawk is proving invaluable as a lerning project in building My Stearman. I have found the Wing Cabanes to be a weak point. They tend to break rather easily. I'm wondering if a one piece Cabane cut from either Plywood, or Styrene might be better. I have removed all of the tissue from My PT-17, and am gfoing to use a microlite covering instead. I also got rid of the Du Bro 1/2A aileron strips. I will still use a similar setup, but made lighter. I dont want any external non scale things protruding unless there is no other way. I am sorry I have no photos, but soon I will have time to go through the ordeal of editing, and resizing them to post.

[davidchoate]

Finally got the top wing on. I had to redo the cabane struts like 5 times. No one method seems easier than another. It just takes time, and use SLOW curing glue. Now the wing struts. The ones on the Plan are too short. Think I added a bit too much dihedral. I have skinned the Stearman,and am replacing the CA hinges with pin, and hinged. I have to modify slightly for this, but it is worth it. I will build a Thomas Morse Scout Kit next before final assy for more experience. Is there ever any "Decolage" set into the top wing? I set them and the Stab at zero. It is 3 CH RC. And thanks David L. for the Propwash advice.

[David Lewis]

With positive stagger, occasionally you will see the top wing with a little higher incidence than the bottom wing. The top wing stalls first, which creates a nose down pitching moment.

[davidchoate]

I have made great progress. Building that little Walnut Hawk really gave Me much needed experience in biplane wing setups. I have all the photos, and one day I will post them. I just hate resising them. I need a super cheap camere on a phone that I can just down load, but I'm back On the Stearman, and its lookin good.

[davidchoate]

Well the Hawk Experiment was worth the effort, and not only did I learn about Biplane wing attachmeny, but I discovered the Curtis Hawk to be one of the coolest and interesting Planes ever. There were so many variants, and color schemes. I Googles images, and it was like You could see this Plane evolve from a small Radial Engine into a God knows how many cylinder V-? I counted 14 exhaust tubes on either side. I want to know more. Ernst Udet sold His Soul (literally) to the Devil for a pair of them. I still need a different camera, but managed to get a few pics on My neighbors Phone and can post them. I will go into details more tomorrow. I do not know the exact specs, but I highly doubt that the last model needed two wings. It also appears to have a gear drive, and to My delight a 3-blade prop. The Hawk is just a cool looking Plane. I am certainly going to do a larger one at some point. But back to PT-17. If you look at the pic; I figured out that if you can dry fit and mark, individually, each strut or cabane to its place on the lower wing and fuselage, that you can glue enough parts on to make the wings have enough integrity (without changing location) so that It can be put together without constant ly pulling one strut out of place as You go to put another in. And I had real problems with the strength of the strut assy. joints not holding. (I made at least 4 or 5 do overs on the Hawk. ) So I made small holes in the struts with hand drill, and lashed things together, and applied Very thin CA (srface area is strength. Thanx David Lewis). And also I will use them as a part in the wire rigging.

[heywooood]

For stronger struts on flyable biplanes, I would buy basswood sheet in 1/16th thickness depending on the scale of the model and then, using the plan drawings as a template, cut out in one piece each strut. Then sandwich it in 1/32" thick balsa - then sand the strut to its scale thickness and profile. This makes for much stronger struts as you no longer have any glued joints AND you have a basswood core.

[davidchoate]

I learned a lot about wing struts here.