ARF Stearman PT-17 from Maxford USA build log

[bicyclemonkey]

Here's an assembly article from Electric Flyer Magazine...covers the whole thing. I studied the one they did that covers my 76" TigerMoth and it was a big help.

http://electricflyermagazine.com/page22.html

 

[randelora]

Wow, Thanks I can't believe how good the model looks in the cover photos. The only thing that bothers me is that ugly radial engine. I'm gonna have a lot of work to do to make that look scale.

 

[bicyclemonkey]

The dummy radial just needs some dry brushing. I always build ARFs bone stock and get the maiden flight over with before I do any scale detail work. I started doing it this way after watching my cousin spend about 40 hours decking out a little Great Planes Nieuport 11 only to kill it on the maiden flight.

 

[earthsciteach]

BM-I've already saved a bunch of pics of the stock PT-17 radial. In terms of scale realism for this model, the radial is the weakest point. It looks pretty awful, in fact. But, I can make it look pretty decent with only a small amount of work. All it needs is some dummy plugs and wires and whatever those tubes are that connect the cylinders. I guess those are the fuel lines. A bit of silver paint and she'll be an award winner!

Oh, and if anyone out there has a good pic of the front AND rear cockpit stock instrument panels for a 1943 PT-17, I'd really appreciate a copy of it. I'm going to build my own instrument panels.

 

[bicyclemonkey]

and whatever those tubes are that connect the cylinders. I guess those are the fuel lines

Are you talking about the pushrods?

 

[earthsciteach]

No, not the vertical rods. I'm talking about the lines that span between some of the cylinders. I don't believe the 1943 220 hp had external push rods. Here's a pic:

 

[randelora]

This is must be a rare engine for the stearman. Every engine picture I could find shows push rod tubes.

 

[earthsciteach]

From my research, the engine with the external pushrods is the Lycoming R-680. Those airplanes fitted with the Lycoming engine were designated as PT-13s by the USAAF. PT-17s were powered by a Continental R-670 engine. There was also a PT-18 model which had a Jocabs R-755 engine.

There were also many other variants of the bipe. The Navy had the N2 and N2s. Then there were a few civilian variants, as well. There was even a PT-27 which was owned by the USAAF but flown by the Canadian Air Force. This model had an enclosed canopy for cold-weather flying.

Then, throw in all the modifications people have done through the years, like hanging a 450 hp motor on the plane, and it becomes a bit fuzzy to determine what motor is correct in the pictures on the web!

The first pic below is the Lycoming R-680 of the PT-13 variants. The second is the Continental R-670 of the PT-17s and the final is the Jacobs R-755 of the PT-18s.

 

[earthsciteach]

Here is the specific plane that Maxford's PT-17 is modeled upon. John Mohr is quite an accomplished pilot and puts on a very impressive show with his bone stock, 225 hp PT-17. I have always loved Stearmans. This guy sure can fly one!

 

[bicyclemonkey]

Continental 670 part list

 

[earthsciteach]

Very nice! Thanks for the link, BM!

 

[randelora]

All the planes I looked at had the Jacobs R-755. From what I read its one of the more popular engines because of power to weight ratio and fuel injection. I'm gonna finish mine with the Continental. It looks like it will be the easiest on to copy. I do think the Jacobs is a prettier engine with the exposed push rod tubes and ignition harness ring.

 

[bicyclemonkey]

So I guess this is finished? How did it fly?

 

[earthsciteach]

No, I haven't built it, yet. I still need to order the motor and servos. How is your Neiuport coming along?

 

[bicyclemonkey]

No, I haven't built it, yet. I still need to order the motor and servos. How is your Neiuport coming along?

The same HA!

 

[earthsciteach]

I received a nice reply from the pilot who owns the Stearman that Maxford's is modeled after. I had emailed him asking if he would be willing to email me some pics of his instrument panels. Here's his reply:

Hi Patrick,

Thanks for the great email with all the nice accolades. I'm glad you enjoyed my routine as much as I enjoy performing it in the Stearman. I, like you, would also watch the Stearmans perform at Oshkosh and knew I would have one. I am a big RC nut as well and learned so much of my acro flying by building and flying models. I did not directly furnish Maxford with pictures or expertise, it came from a friend who is the editor of the AMA magazine. Unfortunately the scale leaves a little to be desired in my opinion and I don't know how it flies. I can certainly furnish you with cockpit shots of the panels when I get to Florida to work on the plane. It is in Lakeland for the winter and I am in Minnesota. Another friend of mine purchased a Stearman built by Banana hobbies and it looks great and flies great as I have flown it. I will try to send you a picture of it. Good luck with the Maxford model, let me know how it flies.

Regards, John Mohr

 

[randelora]

Hey Teach, Thats awesome that John Mohr wrote back to you! He definitely sounds down to earth. I just received my stearman today along with the cockpit upgrade. I will try to upload some pics for you tomorrow. As John stated the scale leaves a little to be desired and I agree.

 

[earthsciteach]

Thanks, Randelora! What is your opinion of the quality, so far?

According to the manual, I've done all I can do until I order the electronics. So far, its been fairly simple. The vertical stab did not have the CA hinge slots cut, but that really was no big deal.

Now, I just have to get clearance to order the motor/props/servos/servo extensions from my wife. Christmastime is not a good time to be in need of RC parts. Sure, I could put those on my list, but I'm pulling for a Dremel workstation.

 

[earthsciteach]

FINALLY placed the order for the parts necessary to make this thing fly. I think it was a new record in order processing - placed the order at 10:42 am and received the "order shipped" email at 11:07 am. Can't beat headsuprc.com!

 

[earthsciteach]

The Stearman is scheduled to take to the air tomorrow morning, somewhere between 8 and 10 am EST. All of the electronics are installed and I'm about to stick the rx in and test the motor and servos.