CW-21: how much can it be improved?

[tomo pauk]

The atypical American if there was ever among the fighter aircraft. Light, small, with excellent rate of climb (even if we dismiss the factory claims of over 5000 fpm). Looks like it used only 750-775 HP to make 314 mph.
So - would it bring anything to the table if it can be improved with better engines, protection, firepower etc?

 

[Shortround6]

Ok, just so we all know something about what we are talking about.

CW-21

CW-21B

Curtiss-Wright Model 21 (aka CW-21 Demon) - RC Groups

Curtiss-Wright CW-21 Demon Interceptor

Please note that engine specifications are a bit confusing. Many sources saying the engines were R-1820G-5s with no reduction gear to propeller. One list of Wright engines seems to indicate that geared engines RG-1820G-5s were used (or at least used in one CW-21)
In any case the FAA type certificate for either engine says 1000hp for take-off at 2200rpm using 41in and allowed for 5 minutes. Mac continuous power was 850hp at 2100rpm at 6,000ft in low gear and 750hp at 15,200ft in high gear. High gear was also allowed to give 810hp for take off at high altitudes (7000ft ) for one minute. Yes I know they over lap but that is what the type sheet says.
Please note the ungeared engines weighed about 1130lbs (depends on carb and magnetos fitted) and 1230lbs for the geared version. For those who dream of sticking in R-1820s from the FM-2 Wildcat, they weighed 1333lbs.

 

[tomo pauk]

Thank you for fleshing-out my post
I've look at the list of Wright engines, the GR-1820G5 is the commercial engine that is listed as installed on the CW-21. Almost all GR-1820G1 to G5 types of engines are listed as commercial types in the list. The only GR-1820G2 engines that are listed also as military types were the G2 and G2S (22 produced all together) and G5
The R-1820G5 is listed under military engines, and the CW 21 is not listed as the user of that military Cyclone. Main users were the Buffalo and Grumman biplane fighters. These military engines without reductionn gear were G5, but there was also a small run of geared R-1820G5 engines (R-1820-39 Army nomenclature) used on (X)B-17.

So back on topic. There was actual proposal to install the V-1710 on the CW-21. Had that succeeded, the pattern looks like MC.200 -> MC.202?

 

[Old Wizard]

 

[Shortround6]

Another version was the CW-22 or SNC-1 Falcon.

0ver 400 built.

One question I have is how much can the basic design be developed or was it close to it's limit?
The CW-21 used an R-1820G engine when the G-100 series was already in production and the G-200 series was just months away from being introduced so the Airframe division must have been aware of the general developments in the engine division of the same corporation.
Why didn't they use the more powerful engines? Too much stress on the airframe?

 

[Capt. Vick]

Not really part of the discussion, but I believe I read somewhere that the name DEMON was applied to the plane in error, it instead being simply a shortening of the word DEMON-strator in (corporate?) literature, as in Curtiss-Wright CW-21 Demonstrator. Just sayin'.

 

[Graeme]

The CW-21 always looked to me to like Curtiss fired the draughtsman responsible - filled in that fuselage and moved onto the P-36.

 

[Shortround6]

The thing is the CW-21 was the later design, first flew almost 3 1/2 years after the Hawk 75.

 

[Capt. Vick]

So it's a Hawk on a diet?

 

[tomo pauk]

A bonus question: what does the airfoil "Curtiss CW-19 Spl", used on the CW-21/22 aircraft, stand for?

 

[Shortround6]

Don't know but it dates to the CW-19L

Certified 12-3-1935, The "slats" were later discarded.
a two seat, side by side, light plane that was the result of a Bureau of AIr Commerce (BAC) contract for a light plane constructed using the same techniques as used in large, all metal airplanes. Powered by an R-266 90hp 5cylinder engine it weighed 1154lbs empty.
wing was of 35ft span, 174 sq ft (sound familiar?) 84in cord at the root and 40in cord at the tip. Either a second plane was built or original was repowered using a 145 Warner Scarab engine (CW-19W). Speed went from 130mph at sea level to 162mph. empty weigh 1360lbs.

The CW-19R had the seats behind each other and with the Wright R-975 420hp engine empty weight went to 1980lbs but all the weight was not due to the engine. Same wing span, area and cords. The plane used a 5 spar wing construction, ribs were placed at 20in intervals, split flaps covering 55% of the span were fitted (but were not to be lowered below 100mph.) a 35 gallon tank (48 gallons optional) was in the wing center section each side of the fuselage. Put on the retracting landing gear of the CW-21 and you get the CW-22.
The original CW-19L was supposed to be almost stall and spin proof. A common goal of light plane/s designed in the 30s.

 

[Old Wizard]

 

[GregP]

Ref #9, no, it's a Hawk in a corset! Better than a pig-in-a-blanket ...

 

[Graeme]

The thing is the CW-21 was the later design, first flew almost 3 1/2 years after the Hawk 75.

Thanks mate - poor research on my part.

 

[Shortround6]

Actually the CW series started about the same time, However the Hawk 75/P-36 was designed in Buffalo and the CW series was designed in St. Louis. About 660 miles apart.

 

[wuzak]

Actually the CW series started about the same time, However the Hawk 75/P-36 was designed in Buffalo and the CW series was designed in St. Lewis. About 660 miles apart.

St Louis?

 

[Shortround6]

Correct, my bad.

 

[wlewisiii]

Found this old thread and got pondering. What about the R-2000? Size is good, several hundred pounds heavier but lots more horsepower.

Then I looked at when it was available... 1942... < sigh > Back to pondering.

It was a neat looking plane, be nice if it were a practical one too.

 

[FLYBOYJ]

Found this old thread and got pondering. What about the R-2000? Size is good, several hundred pounds heavier but lots more horsepower.

Then I looked at when it was available... 1942... < sigh > Back to pondering.

It was a neat looking plane, be nice if it were a practical one too.

I've always been intrigued by this aircraft. The airframe looked so light, I don't know if you can up the horse power without having the airframe bend.

The old publication "Air Enthusiast" issue 16 has a great article about the CW-21.

 

[wlewisiii]

I've always been intrigued by this aircraft. The airframe looked so light, I don't know if you can up the horse power without having the airframe bend.

The old publication "Air Enthusiast" issue 16 has a great article about the CW-21.

The light frame is a valid concern considering the trouble they had with the P-36 and how much they strengthened things for the P-40.

I'll have to see if I can find that issue. Thanks!