Engine Continental Hp

Windmill Lag Hinge
Construction photos of the prototype Kellett K-2 autogiro. (Kellett Photo)
Kellett Rotor Pylon

Tail shock strut on Kellett K-2 and K-3 autogiros. (Kellett Photo)

Continental R670 210

Kellett K-2 engine and mount Continental R-670 160 hp. Note horseshoe shaped wood engine hearer. (Kellett Photo)

aluminum streamlined struts. The front spars carried the landing gear loads from the wing to the fuselage top longerons.

The entire autogiro including the rotor blades was fabric covered. The rotor system was similar to those used on the Pitcairn Autogiros with some exceptions. Most noticeable was the wider chord rotor blade; 23 inches instead of the 18 inches used on the Pitcairn blades of similar gross weight autogiros, keeping the same thickness ratio for the rotor airfoil. The steel tube spar was made from 2Vs inch diameter instead of the on the Pitcairn light autogiros. This had a secondary importance in the method of assembly of the rib to the spar. Instead of employing the delicate process of spot welding the rib collars to the spar, Kellett pinned the collars using a 1/8" clevis pin through the spar kept in place with a cotter pin. The rest of the blade assembly was the same as the Pitcairn blade.

The same blade dampers were installed, the stainless steel trailing edge had the same slip joints, the same fittings were used to attach the droop cables which held the blades while they were not turning. The leading edge back to the spar was covered with preformed plywood and the entire blade covered with aircraft fabric. The rotor hub, universal blocks (which allowed flapping and lead and lag) and blade root end fittings were the same ones used on the light Pitcairn Autogiros; {PAA-1 and PA-18 series). These hubs and parts were supplied by Autogiros Specialties Company, a mechanical engineering firm which supplied all the early autogiro hubs and parts to Pitcairn, Kellett and Buhl.

The rotor pylon was a pioneer effort by Kellett which they improved and refined all through their models. It was basically a single large round tube with auxiliary light weight struts going aft to the rear of the cockpit. After a

Tail shock strut on Kellett K-2 and K-3 autogiros. (Kellett Photo)

Kellett K-2 engine and mount Continental R-670 160 hp. Note horseshoe shaped wood engine hearer. (Kellett Photo)

Wooden Rotor Blade Spar

few early flights with the K-2, V4" diameter, streamlined rods had to be added to brace the ^ pylon to the upper longerons.

The powerplant was a Continental A-70 seven cylinder radial aircooled engine giving 165 hp at 2000 rpm. The weight of the engine was reported as "between 400 and 415 lbs."

Thrust was provided by a 9 foot 6 inch diameter propeller, either fixed-pitched metal or ground adjustable metal.

In reviewing the flight test reports of early K-1 Autogiros, problems of rotor roughness are mentioned. One complain! was referred to as "wind wobbles"—a kind of lateral vibration caused by improper rotor damper settings or improperly adjusted interblade cables.

Overheating of the Continental A-70 is mentioned during the early flights but seems to be corrected by reworking the cowling around the cylinders. One other thing that seemed to give problems was the rotor runup drive system. Broken ring gears and stripped pinion teeth are often mentioned. Because all these parts are common with the Pitcairn machines, no doubt Pitcairn had the same problems. But references, if any, were not available in research.

Balancing the Autogiro required much experimenting. The storage lank for the air starter was mounted in the tail to improve longitudinal balance. A lead weight was added inside the left-hand wing tip to improve the lateral balance. The pylon needed realigning to achieve proper rotor axis angle fore and aft and laterally. Because the blades have a fixed angle to the flap and lead lag hinges (after rigging), the lateral and longitudinal adjustment of the pylon helps offset the unequal lift on the upwind side of the rotor and the downwind side. This effect was referred to as "mechanical feathering." The rotor blade on the right side (advancing) climbs, and the one on the left side (retreating) descends. This equalized the lift on right and left.

"CAA AIRCRAFT LISTING" KELLETT K-2-A, 2 PO CLAg, 2-431

Engine Continental R-670 210 hp

Fuel 35 gals. (One in fuselage 28 gals.

and one in fuselage 7 gals.) Oil 5 gals.

Baggage 25 lbs. (Pay load includes 32 lbs.

for parachutes—40 lbs. less 8 lbs. for seat cushion removed.) Standard wt 2265 lbs. Spec, basis Aero. Bulletin 7A, Section 3 Serial Nos. 1 to 12 eligible. EQUIPMENT:(*Means net increase)

Class I: Battery (hot shot); Starter (Heywood) 29 lbs.

Low pressure tires; Propeller—fixed metal. Class III; Nose skid 10 lbs.; Cockpit enclosure 19 lbs.; Propeller—adj. metal 16 lbs*

Seven Kellett K-2 autogiro fuselages on the assembly line. The "landing gear " on the two at right are for mobility while assembling, not for flight. (Smithsonian Photo)

K-2 (Kellett Photo}

Kellett K2 No. 2 t able rotor rigging can clearly be seen.

(Smithsonian Pli

Windmill Plane

Kelkll K2 built in 1932, held CM approval Engine Continental R670165 Itp redesigned as K3 with KintierCS 3 65 hp. About 24 of the K2 ami K3 were built during 1933 and 1934. (Killett Photo)

K-2 (Kellett Photo}

Kelkll K2 built in 1932, held CM approval Engine Continental R670165 Itp redesigned as K3 with KintierCS 3 65 hp. About 24 of the K2 ami K3 were built during 1933 and 1934. (Killett Photo)

Kellett K2 No. 2 t able rotor rigging can clearly be seen.

(Smithsonian Pli

Approved Type Certificate 437 was \ graded from "A" group 29 to ACT on July 1931.

Specifications

Gross weight "'2265 I

Empty weight 1556 1

Useful load *633 1

Top speed 100 m

Cruising speed 80 m

Minimum speed 24 m

Landing speed 0 m

"■Cross Weight figure is from CAA Spec, T would give a useful load of 609 lbs. "Useful load is from Kellett's brochure

Price: Fly away Factor FAF $7,8 12 were manufactured Standard equipment was: metal propel! Heywood air starter, dual controls and compa (A compass was not required by the CAA ur about 1937.)

Four Kellett K2 autogiros.

(Dallin Phii

Four Kellett K2 autogiros.

(Dallin Phii

Kellett K-3

Tokyo, 1932 —A ceremony for naming thehoo Kellett Autogiros recently purchased by the War Office with public contributions was held at the Yoyogi parade ground this morning in the presence of 20,000 people. Major-General Rensuke lsotaní, dm behalf of the War Minister, who is now in the Kwansai, read a message naming the planes theAikkoku (patriotic) 81 and 82. The planes then made exhibition flights over the parade grounds, (Kellett Photo)

Tokyo, 1932 —A ceremony for naming thehoo Kellett Autogiros recently purchased by the War Office with public contributions was held at the Yoyogi parade ground this morning in the presence of 20,000 people. Major-General Rensuke lsotaní, dm behalf of the War Minister, who is now in the Kwansai, read a message naming the planes theAikkoku (patriotic) 81 and 82. The planes then made exhibition flights over the parade grounds, (Kellett Photo)

The K-3 was an improvement on the K-2, The most significant change was the substitution of a Kinner C-5, 210 hp engine for the Continental A-70,165 hp plant. The Kinner boasted 210 hp at 1900 rpm. The weight of the engine was reported "under 420 lbs." The low weight-to-horsepower ratio was somewhat in favor of the Kinner. The K-3 used an 8-foot 10-inch propeller.

Optional items were a "coupe' top" and a safety nose skid which protected the propeller in case of a noseup.

The horizontal tail plan form was changed for a more pleasing rounded shape on the elevators and stabilizer.

"CAA AIRCRAFT LISTING" KELLETT K-3, 2 PO-CLAg, ATC 471

Engine Kimmer C-5 210 hp

Fuel 35 gals.

Oil 5 gals.

Baggage 25 lbs. (Pay load includes 2

parachutes 20 lbs. each)

Standard wt. 2400 lbs.

Spec, basis Approved Type Cert. No. 471

Serial Nos. 2,12,14 and up mfrd. prior to9-30-39 eligible. Approval expired as of that date. EQUIPMENT: (* Means net increase) Class I: Battery {2 dry ceil); Starter (Heywood): 7.50-10 tires; Adj. meter propeller. Class III equipment: Cockpit enclosure 24 lbs.; Nose skid 10 lbs.

Approved Type Certificate 471 was granted March 26, 1932.

Specifications

Gross weight 2400 lbs.

Empty weight 1647 lbs.

Useful load 753 lbs.

Top speed 110 mph

Cruise speed 90 mph

Landing speed 15-20 mph

Records indicate that six were built. Two K-2s were modified to K-3s. One went to the South Pole with Admiral Byrd, This was donated by the Pep Boys of auto parts stores fame. It was N 12615. Two were sold to Japan.

Standard equipment was: adjustable metal propeller, Heywood air starter, navigation lights and "Hotshot" (dry) battery.

First autogiro in ¡he Argentine being inspected by army officers p vious to first flights. Vie pilot is Edward E Denniston of Phi delphia and the autogiro is a Kellett K-3 model manufactured in. United States by Keilett Autogiro Corporation. The navy officers. Captain Marco Zarr and Captain Mermos Hermosa and the set is at Punta India Military Airport, Buenos Aires, Argentina.

(Kellett Pho

Demonstration of the Kellett Autogiro at Palermo, Buenos Air. Argentina. This was the first autogiro to be flown in the Argenti and created wide public interest Mr. Leigh Wade, Kellett represt tativein the Argentine, is at the right, and pilot Edward E Denn ton at the left (Kellett Pho

Kinner Motors

KËLLETT K-3 ENGINE KINNER 210 HP

KellettK-3 vutogirowiththeByrdAnlardicExpedition in 1933-1934. BillMcCormtc, a Kellett test pi hit was the pilot. Next to theaut the men are digging a "Pilgrim" airplane out of the snow. A mound of snow can be seen where another airplane is burned

(Kellett Pj

Kellett Autogiros
Admiral Richard E Byrd christening the Kellett Autogiro, which accompanied his Antarctic Expedition at Central Airport. Camden,, Jersey in 1933. (Ke"elt Pf

Kellett Sky Ads

(Wide World Photo)

Another effort of Kellett Autogiro Co.: manufacturing towing and leasing "Sky Ads."

(Wide World Photo)

In 1932 Kellett was featuring Sky Ads in addition to Autogiros. These were font high cloth letters made from red bunting and supported with bamboo poles. The letters could be readily assembled into words and messages and towed behind the autogiro. The combination had the double appeal of the autogiro and the Sky Ad.

Later messages were made up and leased to fixed wing operators for their use behind air planes. In 1937 Kellett sold the entire Sky Ad franchise to a local airport operator retaining only the patents.

^VftKWtiE INTERLUDE

Autogiro towing sky ad in August 1932. Hangars at old Philadelphia Municipal Airport at left.

(Kellett Photo)

Autogiro towing sky ad in August 1932. Hangars at old Philadelphia Municipal Airport at left.

(Kellett Photo)

Kellett K-4

Kellett Autogiro Nc12691

Kellett K-4, last of Ike Kellett Autogiros with fixed vtinjp. This was actually built from K-2 Serial No. 3. It was a mystery to the author why Kellett had gone back to the parallel-chord elevators in this model until itwas discovered thai this autogiro was actually K-2, serial 3. The

K-3 series showed a more pleasing curved trailing edge.

(Kellett Photo)

Kellett K-4, last of Ike Kellett Autogiros with fixed vtinjp. This was actually built from K-2 Serial No. 3. It was a mystery to the author why Kellett had gone back to the parallel-chord elevators in this model until itwas discovered thai this autogiro was actually K-2, serial 3. The

K-3 series showed a more pleasing curved trailing edge.

(Kellett Photo)

In 1933 Kellett announced a new model, the K-4. The most noticeable change was the absence of the familiar turned-up wing tips. A beautiful wing tapered in plan and thickness had a single dihedral angle which put the tip at exactly the same place as the top of the turned-up tip. The landing gear, too, was somewhat simplified. The rotor pylon used the same large diameter forward member with only one aft member. But retaining the side braces as in the K-3. The appearance of the horizontal tail caused some confusion. When the K-3 was built, the horizontal tail had been redesigned to a rounded elevator. The K-4 showed the old K-2 square elevators. Actually the K-2, serial #3, was modified to make the K-4. A later Continental R-670 giving 210 hp was installed with a ground-adjustable Hamilton Standard aluminum propeller.

The fuselage, of course, coming from the K-2

serial #3, was gas welded steel tubes. The wing was wood with a plywood cover. The tail was wood with a fabric covering.

No price was announced. Only one was built. There is no record of a CAA approved Type Certificate being obtained. The autogiro was reported to have been sold to the Steel Pier in Atlantic City, New Jersey.

Specifications

Gross weight

2400 lbs.

Empty weight

1620 lbs.

Useful toad

780 lbs.

Top speed

114 mph

Cruise speed

94 mph

Landing speed

not given

Rate of climb

940 ft./min.

Absolute ceiling

14,000 ft.

Service ceiling

12,500 ft.

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Responses

  • milen
    How is steel tube spar of a rotor blade made?
    5 years ago

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