stunthanger.com

Building Tips and technical articles. => 1/2 A building. => Topic started by: 944_Jim on November 01, 2017, 08:32:51 AM

Title: Scientific 21" P-40
Post by: 944_Jim on November 01, 2017, 08:32:51 AM
Hi all,

I came across a 21" wing span Scientifc P-40 Warhawk kitted shortly after 1960. This one is a profile model, with plastic cowl, and a symmetrical wing.

It is new in the box, only some hardware was missing. All wood, decals, and plans have been scanned in order to scratch-build later if I desire.

For now...the dilemma is to build around a suitable powerplant for intermediate stunt. The firewall/plastic nose cowl iss set up for an 8cc Babe Bee or better reedie (Golden Bee, Black Widow).

I have on hand one Golden Bee and a new AP Wasp with matched black plastic engine mount. The Golden Bee is 1/32" longer, and weight is just about the same. Using the AP will require the use of an external tank, which should mount right on center of gravity (as well as being as large as 1 ounce).

The firewall will probably get mounted tonight. Looks like I'll make an extra firewall to sandwich the landing gear...and pull the firewall back on the fuselage the same thickness as the second firewall in order to keep the overall length the same.

Feel free to make comments concerning engine choice first, anything else next.
Title: Re: Scientific 24" P-40
Post by: john e. holliday on November 03, 2017, 11:50:15 AM
Any of todays updated Cox reedies should do the job.    D>K
Title: Re: Scientific 24" P-40
Post by: 944_Jim on November 04, 2017, 10:55:41 PM
Some more pics:
Title: Re: Scientific 24" P-40
Post by: Dane Martin on November 05, 2017, 09:33:05 AM
Some more pics:

Wowzers!!!
Title: Re: Scientific 24" P-40
Post by: 944_Jim on November 08, 2017, 06:31:23 PM
Well, I have the landing gear wire mounted/wire-sewn.
The firewall has been drilled for the engine. Right now, I plan on going with the AP Wasp. The engine cowl hasn't been glued/trimmed to fit. The AP mount HAS been drilled to fit the Golden Bee pattern in case I wuss out on the AP.

The wing needs to be glued in, rear landing gear and elevator installed, and a tank fitted.

Then it's off to the paint booth!

Hopefully this flies Thanksgiving.
Title: Re: Scientific 24" P-40
Post by: Paul Smith on November 09, 2017, 08:01:36 AM
If I was building that or a similar model, I would cut a hole in the body and center the fuel tank behind the engine.  They draw a lot better on the centerline.
Title: Re: Scientific 24" P-40
Post by: 944_Jim on November 09, 2017, 11:00:09 AM
Hi Paul,

I appreciate your response. I'll look into that, but am afraid if weakening this fuse because of it's age.

The good thing about the Wasp is that the muffler-mounted pressure tap will be just above the tank when the plane is on it's wheels. I need to try this engine on a stand on ptessure with the tank.

Thanks for dropping in!
Title: Re: Scientific 24" P-40
Post by: Dan McEntee on November 09, 2017, 02:13:15 PM
    I think the Wasp will be twice the engine that the Golden Bee is and will really be a hand full. The Golden Bee will be more power that the OK Cub engine it was designed around. If you want a longer run, just find a Cox product engine of the last generation, take off the choke tube and mount it to the firewall, and use a separate tank. The late production Cox product engines were twin bypass port with SPI and are at least equal to the Golden Bee. That and play with 5-3 and 6-2 and 6-3 props and you will be quite happy.
    Type at you later,
    Dan McEntee
Title: Re: Scientific 21" P-40
Post by: 944_Jim on November 27, 2017, 07:45:40 AM
Grrrrrrr! Decals were a pain in the patootie! They are 57 years old, and quite brittle. They took almost 2.5 hours to place, and I still need to hit them with a decal solvent. Is it too late for this now?
I hope to fly later this week.
Title: Re: Scientific 21" P-40
Post by: Richard Fleming on July 27, 2018, 03:14:48 PM
Any updates on the first flight? y1
Title: Re: Scientific 21" P-40
Post by: 944_Jim on July 30, 2018, 07:39:57 PM
Any updates on the first flight? y1

Yup:
https://www.coxengineforum.com/t11364-1960-scientific-p-40-profile-kit
Title: Re: Scientific 21" P-40
Post by: Richard Fleming on August 09, 2018, 08:00:54 PM
Nice job! Thank you for the update. The scientific P40 was the very first plane that I flew in Georgia in the summer of 68. Brings back good memories!
Title: Re: Scientific 21" P-40
Post by: 944_Jim on August 09, 2018, 09:20:15 PM
Glad you liked it! I just got through prepping the engine cowl to fit around the AP tonight. Hopefully the whole thing will be assembled and flyjng next week. Maybe I can get a video too.

PM your email address.
I'll shoot you scans of the buildsheet, decals, and parts templates.
I also have the Super Mustang from this series...currently still in the box. The woods, and decals have been scanned (not punched out) as well as the plans.
I hope the Mustang flies as well as the P-40. It has more wing, so I think it will.
Title: Updated with cowl Scientific 21" P-40
Post by: 944_Jim on August 13, 2018, 10:21:09 AM
Added cowl:
Title: Re: Scientific 21" P-40
Post by: Trostle on August 13, 2018, 03:52:42 PM
Nearly 20 years ago, I built the Bell P-63 King Cobra from the same series of Scientific plans.  Built up wing, 28" span.  This was not built from a kit, so the cowl was carved from a block of balsa instead being able to use the plastic shells.  I am not sure which Cox engine this is.  Formed the canopy from a solid piece of plexiglass.  The nose gear is clamped in place when the cowl is bolted in place against the firewall.  Used a simple paint scheme (which was documented) because I did not have much time to do anything else at the time.   Flies quite nice.  It has looped and will fly inverted.  It has placed well in several 1/2A scale contests.

Keith
Title: Re: Scientific 21" P-40
Post by: Trostle on August 13, 2018, 03:54:33 PM
More on the P-63.
Title: Re: Scientific 21" P-40
Post by: Trostle on August 13, 2018, 03:55:45 PM
More
Title: Re: Scientific 21" P-40
Post by: Trostle on August 13, 2018, 03:56:21 PM
More
Title: Re: Scientific 21" P-40
Post by: 944_Jim on August 13, 2018, 06:38:37 PM
Keith,

I like that! Do you still have plans and patterns? I'll trade digital copy for digital copy. My patterns print full size, as does the wing template/instructions. I printed my instructions in "tile/poster" mode and checked against the original (no significant difference).

PM your email...we can trade that way.
Title: Re: Scientific 21" P-40
Post by: Richard Fleming on August 13, 2018, 06:43:52 PM
Keith, that is a very nice and detailed King Cobra. Jim, the P-40 now has a cool hot rod look to it, I like it. Thank you for your kind offer. I have scratched built one a few years back so maybe I can post a picture some day, but need to finish it! LOL I bought a set of decals off the bay a few weeks ago and will scan them and make some new decals from them.
Title: Re: Scientific 21" P-40
Post by: Bill Heher on November 28, 2018, 11:05:04 PM
nice Job! I built one back in `79 with a new Black Widow on it. Spent hours cutting the cowl and fitting it.Did not think to reinforce the seams with fiberglass or silkscreen. flew great- but the cowl blew off the 1st flight! It was a great semi-scale, I had AVG marlings and the tiger mouth, but the cowl flying off took care of `ol Toothy!
Title: Re: Scientific 21" P-40
Post by: 944_Jim on November 30, 2018, 09:06:44 PM
Thanks! Crashed it several weeks back. Lost the cowl in the wreck. Tore the right wing off.
Fixed the wing, picked up a new cowl. Paint doesn't match, so I think I'll practice Beginner Stunt with it, and built a new one from scratch with mods to fix issues. The second one may get the cowl because it just looks so good on the plane!
I plan on plane two being about a 1/2" shorter between the engine and leading edge to move the CG back a bit. The engine will get rotated to about a 45 deg angle outboard to move the spray bar down a but, and the tank will be centered on the hole in the spray bar. At least that is my thinking at the moment. Crash damage.is on CEF (same username).