Scientific Gulfhawk

duaneh Tue May 21, 2024 12:22 pm

One of my favorite planes, the full scale Gulfhawk IV was a Grumman F8F Bearcat flown by Maj. Al Williams shortly after WWII.

Scientific's model of the Gulfhawk was not their typical hollow log, but a profile with a built-up wing.
(I don't have this kit, the picture was grabbed off the net.)

I was fortunate enough to acquire the plan recently, and decided this was a model that had to be built. This plan is better than most Scientific kit plans in that it includes full size views of the wing and tail, lacking only the wing rib patterns. The kit included a plastic cowl and canopy. Lacking these, I made a balsa cowl and incorporated the canopy outline into the fuse profile.

The root rib pattern can be derived from the plan side view. The others are simply adjusted in length by the appropriate amount to produce the taper. I did not taper the thickness of the wing, and don't think the kit wing was either. I did make a few changes. The kit has a straight LE, and of course the F8F wing has a swept LE. I extended the rib noses enough to replicate the sweep. I also added a spar and center section sheeting. The sheeting gives a place to attach the covering. The spar just makes me feel better.

Here are all the parts taped together for a first look.

**944_Jim** Tue May 21, 2024 12:40 pm

Duane,

I'm digging your build! Dave Cowell of DPC Models needs to see this. He has the plans now (thanks to you), and I suspect the cowl is one he has for his P6E offering. I have his P6E and need to check the cowl against the pictures.

The funny thing is I'd love to try your smaller one with my Cox 3-line bellcrank/handle before jumping up to the big guy. You give me inspiration...now all I need is time:

GallopingGhostler Tue May 21, 2024 3:31 pm

@duaneh , thanks for posting a scan of the plan. I looked through my archives referencing Scientific ads and catalogs to find its wingspan without luck. What is it?

In a net search, did find https://outerzone.co.uk/plan_details.asp?ID=15096 Grumman F8F Bearcat by Walt Musciano from American Modeler February 1961, 26in span

Outerzone plan thumbnail.

Given that Walt shows sample McCoy .29 and Fox .19 installations, I gather that Walt perhaps liked to fly with longer lines, hot and fast.

Looks like by the proportions that Walt Musciano did some simplification so it could be kitted by Scientific, like the profile fuselage.

It would not take much for someone to change the colors to post WW2 Navy and return it to warbird status.

rsv1cox Tue May 21, 2024 3:56 pm

Beautiful Duane.

You and roddie excel at Bearcats.

I love the formed cowl. What a neat and clean build.

duaneh Tue May 21, 2024 5:02 pm

GG , the span measures 19-1/2". Scientific always rounded up, so it would be listed in ads as 20". I doubt this Bearcat is related to the one on Outerzone. Walt was the most prolific designer I know of, a search on OZ of "Musciano" returns 154 hits.

rsv1cox, I'm hardly a master, but I do enjoy hacking away at balsa.

getback Wed May 22, 2024 6:23 am

Well that's some serious hacking at balsa right there LOL Very nicely done You do a good job of figuring the scale something I just can't seem to get a grip on . Can't wait for the paint /covering finish !

Mike1484 Wed May 22, 2024 7:20 am

Berkley made a Bearcat kit. One of my friends made a model of the white Smirnoff racer and powered it with a Veco .35. It flew well but it was faster than hxxl. Duaneh you build some nice models. I always look towards your next build.
Mike1484

duaneh Wed May 22, 2024 9:23 pm

Actually, the monokote has been on for a while, but painting the cowl took a long time. Three colors, and 48 hrs between coats, so I've literally been waiting for paint to dry.
Be careful if you're using a touch screen, the blue is still tacky.

The color scheme was a bit tedious, as there are a lot of different elements to apply. I even left a few of them off. Was worth it in the end, because it is quite colorful.
Final weight came to 7 oz., wing area 94 sq. in.

GallopingGhostler Wed May 22, 2024 10:10 pm

@duaneh , you did a very nice job on finishing, paint matches the Monokote, engine installation is very cleanly and neatly done, fanning "sunburst" color striping adds a touch of class mimicking the real thing.

Just looking at the proportions, it certainly tends to resemble the same period Cox TD-3 ready-to-fly, especially the wing outline.

duaneh Thu May 23, 2024 1:21 am

You're right, GG.
I never thought about it until you mentioned it, but there is a resemblance in the wing outline and especially tip shape.

roddie Thu May 23, 2024 12:03 pm

WOW Duane! Nice job man!! I like the way you inset the front-inner corner of the fuel-tank into the cowl. I suppose it was necessary.. but it's nice and neat.

GallopingGhostler Thu May 23, 2024 12:21 pm

@duaneh , you lucky dog Very Happy

to own that TD-3 classic! Wink

And, in such a nice NOS condition! Thumbs Up

duaneh wrote:I never thought about it until you mentioned it, but there is a resemblance in the wing outline and especially tip shape.

However, it would not surprise me that the Scientific would be the better flyer. Just looking, it is not nose heavy like the TD-3 and has a symmetrical wing rib profile so to fly inverted equally well.

The engine cowling on this profile adds a touch of class. For a quick build though but a touch less classy, one could go cowl-less with one of those engine mounts like that on the old Sterling Beginner and Midwest Warbird half-A profiles that Bernie, Matt, and Brodak sells.

https://coxengines.ca/cox--049-engine-firewall-mount-control-line.html

Except that current stock is in black.

But, the enclosed cowling speaks volumes on perhaps one of the prettiest C/L half-A's that Walt Musciano ever designed. Hand Shake

roddie Fri May 24, 2024 1:47 am

Just for a comparison.. the version I designed for the 1st CEF speed contest 10 years ago has a solid/flat wing of 17" span, 70 sq. in. but weighs-in at 7.2 oz. It's a lead-sled.. Yours will surely fly with more maneuverability Duane.

akjgardner Fri May 24, 2024 4:29 am

Beautiful Airplane Duaneh . A+++++++++++

getback Fri May 24, 2024 5:45 am

Beautiful , you knocked it out of the park again ! Love the paint scheme going to look good fling ! Thumbs Up

rdw777 Fri May 24, 2024 10:15 am

Beautiful job on the model building and exemplary on covering and finish…Excellent subject too!!

KariFS Fri May 24, 2024 1:05 pm

What a beauty bounce

Adding the spar was probably a good idea, especially now that the wing chord increased. I guess a lot of old plans relied on the stiffness of the covering material to keep the wing from flopping around. Oracover won’t give that kind of support, so the spar is a good addition.

Again, great looking plane, great skills!

**944_Jim** Fri May 24, 2024 8:09 pm

Duane,
I'd like some details on that tank. Maybe I need to use.my PC to get a better view of it.

And when is the maiden flight scheduled?

duaneh Sat May 25, 2024 1:30 am

Thanks guys for all the kind words.

Kari, Scientific used a heavy leading edge which was the only “spar”. My LE is far less substantial, the full depth spar and sheeting take the loads more efficiently.

Jim, I made a “mailbox” style tank of ½ oz. capacity. There isn't a better view of it because my soldering stinks. The only thing that's unusual is the pickup tube, which is curved inside the tank so that it can exit at a more convenient angle.
Maiden will be as soon as the weather settles down. The forecast is storms for the holiday weekend.

**944_Jim** Sat May 25, 2024 8:39 pm

Duane,
I love your tank! For some reason mailbox tanks appeal to me. I guess it is because I was used to seeing them in ads as a kid.

I have more questions regarding the build. I see the trailing edge is notched. I think I see the leading edge appears to be notched wing runs with a slat behind another run of balsa. Is the forward edge grooved for the slat? Or do I just see something telling me I need glasses?

duaneh Sun May 26, 2024 10:20 am

Jim;
Yes, the trailing edge is notched and is just like the kit.

The LE is a 1/8 sq. stick glued to a piece of 1/8 x 3/8 in a T section. The ribs have a 1/8 notch in the nose. The advantage of this method is the rib noses can't get out of line. If this is used in conjunction with a notched full depth spar and notched TE, the entire wing can be assembled dry and lined up before gluing.

Here's a quick visual of the pieces.

Assembled

After sanding the LE to shape.

**944_Jim** Sun May 26, 2024 10:34 pm

Yeah, that is one solid wing! Thanks for the details. Doing that by hand would be a bear. I assume you did the cutting job on a machine.

I'd love to be there when it flies.

duaneh Mon May 27, 2024 11:47 am

Jim, I mostly cut out parts on the band saw.

If you can make the drive from MS, come on up to the SIRS Club Vintage Model Aviation Days on June 22-23. We are located near the small town of Mclean, IL.
We will be flying many 1/2A CL models, including Cox and other RTF plastics. I will have the Gulfhawk, TD-3, the Top Flite Junior Aces, and others.

roddie Mon May 27, 2024 8:59 pm

duaneh wrote:Jim, I mostly cut out parts on the band saw.

If you can make the drive from MS, come on up to the SIRS Club Vintage Model Aviation Days on June 22-23. We are located near the small town of Mclean, IL.
We will be flying many 1/2A CL models, including Cox and other RTF plastics. I will have the Gulfhawk, TD-3, the Top Flite Junior Aces, and others.

I so hope that you will share photos from that weekend!

GallopingGhostler Wed Jun 05, 2024 12:01 am

Congrats and thanks, @duaneh for sharing the wealth and posting your plans plus decals on Outerzone! Very Happy

https://outerzone.co.uk/plan_details.asp?ID=15331 Grumman Gulfhawk by Walt Musciano from Scientific 1961, 19.5-in span

Outerzone plan thumbnail.

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