smkrcflyer

I picked up a used Saito 325R5 and started looking for a plane for it. After many hours of searching I decided on building a PT-23. I purchased a Dynaflite PT-19 kit to use for the build. I’m planning to make some changes from the standard kit build. Other than the modifications for engine I’m going with a three piece wing. The other thing I’m thinking about doing is mounting the wheel struts into the wing without using the kit wire. I noticed Hangtimes Hobbies PT-19 is done this way and I like how it looks without the wire showing on the bottom of the wing. I already purchased the struts but after looking at it I’m concerned about not having any give side to side. So I may go with the kit wire and robart struts. Any advice on the struts will be helpful.

I will be using Solartex and most likely in the blue & yellow scheme but I did see one with silver fuselage and yellow wings that I like.

I don’t have a lot of building experience so any advice will be appreciated.

I started the build and I have some of the fuselage done and the tail sections are done. I’m working on mounting the engine now. I will post some pictures soon.

TomCrump

I used Robart oleos on my similar sized Hangar PT-19. They attached to the cut off wire of the stock landing gear. I encountered no problems with that setup. If that's any help.

SrTelemaster150

The design of the DF PT-19 landing gear is such that the long section of the "Z" acts as a torsion bar to absorb impact on landings & tranfer the gtorque into the wing root.

If you change this design you need to make sure you beef up the wing, especially where the gear mounts.

TomCrump

Depending on which struts you purchased, they should have spring shock absorption built in. That's not to imply that a little LG mount reinforecement wouldn't help.

raptureboy

Hi Steve, looking forward to seeing this build and what you do. I still have mine in the box and hope to make some attempt at getting it started this winter. Here's a thread I saved for the future. http://www.rcuniverse.com/forum/rc-w...tch-build.html I want to also do the 3 piece wing. That hangtimes bird is so sweet.

SrTelemaster150

It's not the vertical impact that I'm refering to Tom. Its the torque or horizontal twisting force that is present too, especially when landing on grass.

I had to upgrade the OEM 1/4 "Z" shaped wires to music wire because they were twisting & leaving the gear angled to the raer from the proper angle.

smkrcflyer

Thanks everyone for the feedback. I'm going to use the wire from the kit with robart struts.

Thanks for the link Cliff I did follow that build and it contains good information. Hope you get started with your build soon.

SrTelemaster150

That's what I did. Make sure you use a good epoxy to assmble the torque blocks in the wing root.

smkrcflyer

When I started looking into building the PT-23 I noticed the nose was shorter than the PT-19. I did some overlays of the two planes and took some measurements. From this information I determined that cutting 3 inches off the nose of the plane would be put the propeller in about the right location, so that’s what I did. Now I have to make a new firewall because of the taper of the fuselage the one that came with the kit does not fit. The weight 325R5 makes me a bit concerned about using a single piece of ¼ ply so I decided to use two pieces laminated together. One will go inside the fuselage and the other will be larger and overlap the sides of the fuselage so that I can add triangular hard wood.

I also want to pin the firewall to the fuselage sides. I have not done this before so any help with this will be good. Should I use wire or some other material?

SrTelemaster150

It's not weight but vibration that is the bane of firewalls.

Your FA325R5 will be siky smooth compared to single cylinder engines.

TomCrump

For added security, you may want to pin the firewall, too.

smkrcflyer

That's true. Here is a link to my engine running on the Fleet I sold.

http://www.youtube.com/watch?v=HSTyc7YZ008

TomCrump

Nice !

SrTelemaster150

Here's one running on gas although I would have stopped @ CDI/gloe fuel.

http://www.youtube.com/watch?v=hCNCQCPhJLk

That's a prototype module. The production modules will be more refined.

I have a 3-cylinder set-up for my FA512R3 (alcohol version of the FG84R3)

smkrcflyer

TomCrump

Looks good.. I built a firewall exactly like you did, last year.

smkrcflyer

Tom, That's good to know. I'm going to order the struts soon from Robart they have a sale going on. I need to get two sets of retracts for my Hangar 9 P-47 150. My son and I both have one and we want to replace the stock ones.

Michaelj2k

The airframes of the Fairchild PT-19, -23 and -26 are all the same. To get a good look at the firewall, look here. http://www.warbirdalley.com/articles/pt26-fa.htm. The subject airplane now resides in Minnesota.

smkrcflyer

I'm looking into mounting the fuel tank. I have to raise it up to the top of the fuselage to get the center of the tank as close to the carb as possible. Anyone have a good way to do this? I was thinking about building a shelf that I could slide in and out in.

Starting to look at how I'm going to build the wing. My plan is to split the wing a rib W4 this way I can keep the landing gear connected to the center section. I'm going to make four W4 ribs out of plywood. One for each side of the center section and one for each wing panel. I'm going to use aluminum wing tubes with sleeves. For the ribs that the sleeves are going through do I have to replace all the balsa ribs with plywood? Or maybe just make plywood doubles for the center of the ribs where the sleeves go through? The ribs already have holes in them so adding the tube will not be hard.
I'm going to make plywood tabs that will be glued into the wing panels that will slide into the center section. These will have blind nuts in them and a bolt will be inserted from the bottom of the wing to hold the outer panels in place. Does this sound like a good way to do this? I'm not looking to reinvent the way to do this stuff so if someone has a better way let me know?

smkrcflyer

I installed the removable fuel tank shelf. I made brackets in the shape of a C and used landing gear straps to hold it in. The other end sits on a piece of hardwood.
Also got the firewall installed and mounted the engine for the first time. Need to pin it and install tri stock around the outside. I think the engine location looks good.

smkrcflyer

I have the four plywood W4 ribs done. I changed the way I’m going to attached the outer wing panels. I’m going to use a bolt through the wing panel into a T nut in the mating rib on the center section. This way the bolt will be pulling the wing panel onto the center section. I will add an access panel on the bottom to get to the bolt. I will be using a locating dowel on the front and back of the rib.

TomCrump

It's nice to see progress.

smkrcflyer

I did make some progress todayTom. I got the wing mounting worked out and the wing has been dry fitted. I don't know how many times I took this thing apart but I got it worked out.

smkrcflyer

I think I have my engine mounted to high. I was looking at some PT-23 pictures and the engine looks centered in the fuse. I set my engine so the center of the engine is at the thrust line on the drawing. Comparing the PT-19 to the PT-23 the engine prop shaft on the PT-19 does look higher then the PT-23. I think my engine looks better at the lower location. Is it a problem if the center of the engine is not on the thrust line of the plane?

SrTelemaster150

The inverted ranger would have the prop shaft above vertical C/L by necessity while the radial would be more centered.

Look at the fire extinguisher door for a good reference. Isn't the "center of the engine" by definition the "thrust line"? It’s plain that there is a difference in thrust line.