Curtiss 1A Gulfhawk

[FlyingTyger]

History:
The Curtiss Gulfhawk was a one-off demonstration/airshow airplane flown by Al Williams starting in 1930. Which, to me, made this a perfect candidate for the Barnstorming challenge for FF '23.
There were 4 basic versions as this plane went through several modifications. Originally it was mostly a Hawk 1 export version with different tail surfaces and landing gear. This version was powered by a Bristol Jupiter engine built by Bliss and was painted in a red and silver scheme.

The Bristol engine was later swapped out for a Wright Cyclone engine (version #2) trimmed with a ring cowl.

After a crash, the plane was rebuilt with a metal-skinned fuselage (version #3) and given its now iconic orange and white paint scheme. Williams flew this plane through 1936 when he replaced it with the more well-known G-22 "Gulfhawk II", a modified Grumman F3F.

In 1958 Frank Tallman found the airplane and purchased it from Al Williams. He spent 4 years restoring the plane and installed the P&W Wasp and radial bumped cowl that is still on it today. It currently resides in the National Air & Space Museum.

The Model:
I will be building my model as the last version Al Williams flew. This one has the orange and blue scheme with the ring cowl.

I will be using Dick Barron's 1/6 scale plans which the AMA plans service has been nice enough to print at 72" for me. These plans are for a traditional balsa/ply airframe, but I plan to use a mostly foam construction inspired by builds done by Josh Orchard, Carl Lydick, John Morgan, and Keith Sparks. I have been studying these types of builds for the last few years, and have completed some smaller planes trying to learn these foam building techniques. Now it's time to try a large scale airplane!

 

[The Fopster]

That’s a great looking full size subject, and a fantastic scheme ( love the orange!). Good luck - this one could be a beauty.

 

[FlyingTyger]

Plans have arrived!!!

It seems smaller than I imagined, but it is a very bulky plane with a large radial up front. I think it will feel bigger once its in a 3D form.

But now that I have the plans in hand, I can get a better feel for motor and prop selections and start picking up the other odds and ends needed yet.

 

[Tench745]

My S4C scout felt pretty small until I put the wings on for the first time. Each part on its own doesn't feel that large, but once they're all together the scale of the thing hits.

 

[Kartman24]

Watching this build with interest, cool subject..........

 

[FlyingTyger]

Finally off the starting line! With my other projects wrapped up I was able to start cutting pieces for this one.
Since this is a balsa plan being built from foamboard, I have to adjust for the added thickness of the foam. I also scaled the planes up 14% which affected the thickness on the prints. Well, I got very lucky. The fuse is designed to be sheeted with 1/8" balsa. That thickness scaled up 14% calculates to 0.14". That is nearly the thickness of DTFB with the paper removed. At least close enough for me.

I now have all the main fuse formers done.

The next step will be to figure out the firewall.

 

[Off-topic jes]

Finally off the starting line! With my other projects wrapped up I was able to start cutting pieces for this one.
Since this is a balsa plan being built from foamboard, I have to adjust for the added thickness of the foam. I also scaled the planes up 14% which affected the thickness on the prints. Well, I got very lucky. The fuse is designed to be sheeted with 1/8" balsa. That thickness scaled up 14% calculates to 0.14". That is nearly the thickness of DTFB with the paper removed. At least close enough for me.
View attachment 232047

I now have all the main fuse formers done.
View attachment 232048

The next step will be to figure out the firewall.

Looking beautiful

 

[FlyingTyger]

Fuselage progress.

I decided to cut the main inner fuse panels from 1/2" foam since these will carry the majority of the loads. The cabanes, stabilizer, bottom wing, landing gear, and firewall all attach to these. The DTFB formers were then attached around these panels.

I closed in the top of the inner "box" from the cockpit forward. I will do the same at the bottom once I know how I need to shape the panels at the nose.

The fuse was still a little wiggly, so I added some foam board panels on the bottom to help stiffen it up.

The next step will be to figure out the gear mounts. Then I will skin as much of the fuse as possible before removing it from the bench. Hopefully, that way it will hold its shape better and help prevent me from building a twist into it.

 

[Off-topic jes]

Fuselage progress.

I decided to cut the main inner fuse panels from 1/2" foam since these will carry the majority of the loads. The cabanes, stabilizer, bottom wing, landing gear, and firewall all attach to these. The DTFB formers were then attached around these panels.

View attachment 232881

I closed in the top of the inner "box" from the cockpit forward. I will do the same at the bottom once I know how I need to shape the panels at the nose.

View attachment 232882

The fuse was still a little wiggly, so I added some foam board panels on the bottom to help stiffen it up.

View attachment 232883

The next step will be to figure out the gear mounts. Then I will skin as much of the fuse as possible before removing it from the bench. Hopefully, that way it will hold its shape better and help prevent me from building a twist into it.

I love the style, simple, yet strong and compact

 

[cyclone3350]

U R so motivating me to get started on the Fleet. Unfortunately I am literally starting from the beginning. Like an empty basement & a zillion boxes to unpack. Keep posting, can't wait to see it done.

 

[FlyingTyger]

Thanks guys!
Cyclone, I know your pain. I moved just a few years ago and still don't have everything unpacked...

 

[Off-topic jes]

U R so motivating me to get started on the Fleet. Unfortunately I am literally starting from the beginning. Like an empty basement & a zillion boxes to unpack. Keep posting, can't wait to see it done.

sorry man

 

[FlyingTyger]

I started bending up the landing gear and planning the mounts, then quickly realized that I needed to get the interior supports figured out first.

I wanted an internal structure that would support the gear, wings, firewall, and battery loads. The foam may have been able to handle it, but I felt it would start to give way over time.

This internal crutch was assembled from 1/8" lite ply and slides inbetween the two main fuse panels.

The battery tray will be attached to the back of the firewall, which will then be bolted to the front of this crutch. The plan is to have the whole nose removeable for battery changes; but I will get into that more later.

 

[Off-topic jes]

I started bending up the landing gear and planning the mounts, then quickly realized that I needed to get the interior supports figured out first.
View attachment 234048
I wanted an internal structure that would support the gear, wings, firewall, and battery loads. The foam may have been able to handle it, but I felt it would start to give way over time.
View attachment 234049
This internal crutch was assembled from 1/8" lite ply and slides inbetween the two main fuse panels.
View attachment 234050
The battery tray will be attached to the back of the firewall, which will then be bolted to the front of this crutch. The plan is to have the whole nose removeable for battery changes; but I will get into that more later.

Looks great!

 

[Off-topic jes]

I started bending up the landing gear and planning the mounts, then quickly realized that I needed to get the interior supports figured out first.
View attachment 234048
I wanted an internal structure that would support the gear, wings, firewall, and battery loads. The foam may have been able to handle it, but I felt it would start to give way over time.
View attachment 234049
This internal crutch was assembled from 1/8" lite ply and slides inbetween the two main fuse panels.
View attachment 234050
The battery tray will be attached to the back of the firewall, which will then be bolted to the front of this crutch. The plan is to have the whole nose removeable for battery changes; but I will get into that more later.

I love the perfectly fitting ply parts

 

[FlyingTyger]

Got the the gear assembled and soldered up. The main gear were anchored down to some ply mounts using some Dubro gear straps.

A lite ply mount was cut and epoxied in place for the tail gear. Nothing fancy here, just a Dubro bracket and bent wire.

With the gear in place, I was able to put it on its feet for the first time.

This guy is getting set aside now for the next month while I participate in @FoamyDM's Build-ruary Challenge.

 

[Tench745]

This guy is getting set aside now for the next month while I participate in @FoamyDM's Build-ruary Challenge.

What, you don't want to finish this and three other planes in a month!? Looking good so far.

 

[FlyingTyger]

What, you don't want to finish this and three other planes in a month!? Looking good so far.

LOL. If I was 20 years younger, single, and childless maybe I could pull it off. Back when I could survive on just a few hours of sleep each night 😁

 

[FoamyDM]

I am glad you joined the Challenge.

 

[FlyingTyger]

So I cheated a little and ordered a ring cowl from Fiberglass Specialties instead of making one. It arrived today and I couldn't help seeing how the cowl/prop sizing was going to look.

The cowl is actually for the Royal (Marutaka) P-26. I don't have the actual prop yet so ignore that it is a WWI German prop for now; it's the closest 18" prop I had on hand.