Continental XO-1430 Part 2

Continental XO-1430 Development
Part 2: 1932 and 1933
by Kimble D. McCutcheon
Published 3 Aug 2025; Revised 15 Aug 2025

Continental XO-1430 Development Quick Links
Part 1: Introduction and Background	Part 2: 1932 and 1933
Part 3: 1 Jan 1934 to 30 Jun 1934	Part 4: 1 Jul 1934 to 31 Dec 1934
Part 5: 1 Jan 1935 to 30 Jun 1935	Part 6: 1 Jul 1935 to 31 Dec 1935
Part 7: 1 Jan 1936 to 30 Jun 1936	Part 8: 1 Jul 1936 to 31 Dec 1936
Part 9: 1 Jan 1937 to 30 Jun 1937	Part 10: 1 Jul 1937 to 31 Dec 1937
Part 11: 1938	Part 12: 1 Jan 1939 to 30 Jun 1939
Part 13: 1 Jul 1939 to 31 Dec 1939	Part 14: 1940 and Conclusion

16 Dec 1932. Materiel Command Power Plant Laboratory civilian engineer Ford L. Prescott issued Engineering Section Memorandum Report No. E-57-126, "Continental Single-Cylinder Poppet Valve Engine (Progress Report), which concluded that it was possible to design a poppet valve cylinder for high output. Prescott thought that high supercharger boost was undesirable since the supercharger design problem was so difficult that the resulting efficiency would probably be lower than could be obtained with a larger displacement engine of moderate performance. He analyzed the 1,000 hp, 1,008 in³ displacement engine using 12 Hyper No. 1 cylinders for weight and determined it would weigh about 1,000 lb, excluding cooling system and turbosupercharger.

Prescott recommended continued cylinder design studies to fine the lightest cylinder form for moderate ground boosting, and also suggested other engine arrangements should be analyzed to find the most desirable type for development. A cylinder designed along the lines of the Allison high-output cylinder was being tested by the PPL and had proven capable of operation at 3,000 rpm and 419 psi bmep with 48.2 inHgG boost. Continental had begun testing its Hyper No. 1 cylinder. He remarked that the weight analysis of the 1,008 in³ 12-cylinder engine was very disappointing, since the bare engine with geared supercharger would weight in excess of 1,000 lb; this heaviness was largely due use of separate cylinders designed for high specific output. He pointed out that European designs had achieved good specific weights using larger-displacement instead of high-output cylinders. Several options were being analyzed, including a 12-cylinder hex engine using high output cylinders, a built-up steel cylinder and a dry-liner aluminum cylinder.[USNARA RG 342 RD1670, 502-2-108 O-1430 to 340630. 3-4a]

6 Feb 1933. Continental Chief Experimental Engineer R.N. DuBois released "Report of Performance and Endurance Test of Continental 'Hyper' Engine No. 1." The object of this test was to obtain information on the performance and endurance of the engine at high output with Prestone cooling. In summary, the engine developed 310 psi bmep at 2,200 rpm, 250°F jacket temperature, 60°F carburetor air temperature and 30 inHgA boost. At 3,000 rpm it achieved 279 psi bmep. An endurance run at 3,000 rpm, 255 psi bmep and 0.54 lb/bhp/hr brake specific fuel consumption (bsfc) using 24 inHgA boost had begun and 8 hrs had been run by the time the report was released. The first few hours of this run indicated that the cylinder was not getting enough oil and that the piston clearance was low. A squirt hole was drilled in the connecting rod lower end and the piston clearance increased from 0.022" to 0.030". The aluminum alloy rocker box casting failed at 8 hrs because the rocker shaft boss section was insufficient to withstand the 200 lb valve spring loading at 3,000 rpm.

DuBois concluded the cylinder performance was satisfactory; no fundamental defect had appeared during the operating 87 hrs. The Lo-Ex (a low-expansion aluminum alloy) piston did not show the expected bearing qualities and work was indicated on land clearance and top land width to avoid ring sticking and wear. DuBois recommended the endurance run be continued to 25 hrs, using a new rocker box casting and 160 lb valve springs, which had given no previous trouble.

Hyper cylinder No. 1 design featured a 4.625" bore, 5.000" stroke and 84.001 in³ displacement. Its forged carbon steel barrel was screwed and shrunk into a cast heat-treated head of modified Y-alloy with a separate hardened SAE #2340 steel water jacket shrunk over the barrel and head shoulder. The liquid space around the barrel was joined to the head jacket by two flanged connections fastened by studs and nuts. The enclosed single overhead intake and exhaust valves, both sodium-cooled, were operated through rockers from a central camshaft with hollow-faced, large-nose-radius cams. The rockers had rollers at both the valve and cam ends with clearance adjustment at the valve. The valves ran in aluminum bronze guides inclined at 35° to the cylinder axis. The valve seat inserts were cast from a special aluminum bronze, and the exhaust seat was faced with Stellite. The BG 157 spark plugs were inclined 50° to the cylinder axis and were retained in aluminum bronze inserts, screwed and pinned in opposite sides of the head at a 65° angle to the valve plane. The forged Lo-Ex piston had four transverse rubs under its head, three compression rings and two oil rings with vented grooves, one above the piston pin and one at the skirt bottom. All rings were 0.125" wide. The oil hardened, Timken-axle, chrome-nickel-molybdenum steel full-floating piston pin used chill-cast Y-alloy end plugs. Compression ratios of 5.0:1, 5.5:1 and 6.0:1 could be obtained with various spacer and piston combinations. Valve timing was as follows: intake opened at 20°BTC; exhaust closed at 20° ATC; intake closed at 55° ABC; exhaust opened at 65° BBC.

The engine was connected to a General Electric Type TL C-20 dynamometer with a beam scale. Fuel was measured by volume in a calibrated tank; an orifice flowmeter was used for preliminary tests. Air consumption was measured by a sharp-edged orifice in the high pressure air line. Figure 1 shows the test setup. A well-type mercury manometer indicated the carburetor tank pressure. Carburetor air, cylinder and air-metering orifice temperatures were obtained with iron-constantan thermocouples. Oil and coolant temperatures were indicated by "Motometer" vapor-pressure thermometers, and the coolant outlet temperature was measured by a mercury thermometer. A "temperature plug" similar to that used by the USAAC to detect detonation was installed. When indicator cards were desired, a "Farnboro" electric indicator with special Continental disc valve was used and was driven by the engine crankshaft.

All results were corrected to an atmospheric pressure of 29.92 inHgA and carburetor entrance temperature of 60°F; no humidity correction was used. After running-in and subsequent inspection, a run was made to 3,025 rpm, using a neon stroboscope for valve spring and rocker observation. The valve operation was regular and no bounce was seen up to 3,025 rpm. The springs, which were 160 lb tension, were surging sufficiently to mark adjacent coils. Above 2,800 rpm an intermittent clatter was noticed. A 5 hr run, unsupercharged, at 2,800 to 2,900 rpm was run, after which a teardown inspection showed the condition to be satisfactory. On rebuilding, the piston was changed in order to increase the compression ratio from 5.5:1 to 6.3:1 and the 160 lb valve springs were replaced with 200 lb springs.

Runs form 2,000 to 3,000 rpm at 10, 20 and 30 inHgA carburetor intake pressure were made, with results shown in Figure 2; at 30 inHgA and 2,300 rpm the single cylinder produced 75.4 bhp (12-cylinder total = ~905 bhp). The volumetric efficiency and spark advance were shown in Figure 3, the volumetric efficiency being corrected for the compression of the residuals to the supercharger pressure. The volumetric efficiency was quite high and unchanged by supercharger pressure variations. The flat output curve at 30 inHgA boost has not been explained, although from spark advance curve examination it appears the engine is over compressed at the 6.5:1 compression ratio and 30 inHgA boost; and with better fuel the 30 inHgA output curve will show a distinct peak at 2,200 rpm as in the curve at 10 inHgA and 20 inHgA boost, Figure 4 shows the jacket outlet and cylinder temperatures for the same group of runs. The cylinder temperatures were taken just below the spark plug on the cylinder intake side. The curves show the cylinder temperature to be practically independent of boost or speed, so long as the jacket temperature was maintained constant.

Figure 5 is cross-plotted from Figure 2, showing output versus boost at 2,200, 2,500, 2,700 and 3,000 rpm. Figure 6 shows a power curve using for each speed the maximum boost possible at 2,000 rpm without detonation, at fuel consumption at approximately 0.53 lb/hp/hr. Detonation was quite difficult to detect on this engine and a temperature plug was inserted after a piston had been melted through by undetected detonation with excessive spark advance at 30 inHgA boost. Figure 7 shows friction mean effective pressure at 2,000, 2,500 and 2,000 rpm.

Below are the XO-1430 Hyper No. 1 run log highlights.

7 Dec 1932. Start motoring, 5 minutes.
8 Dec 1932. After the rocker box filled with oil, a #55 (0.052") restriction was place in the camshaft oil line. After 5.5 hrs motoring to 1,000 rpm, power running began for 2 hrs and to 1,400 rpm; the cam drive bevel gears were dry.
9 Dec 1932. Oil hole diameter between cams was reduced from 0.063" to #60 (0.040"). Ran 1 hr at 1,400 rpm; the cam drive gears were still dry. A #60 (0.040") drilled plug was installed in the camshaft end to squirt oil onto the gears. The engine was run at 1,600 rpm for 2:45 hrs.
10 Dec 1932. The engine was run to 2,000 rpm and torn down for inspection after 7.5 hrs under power. The intake valve was in good condition but not turning; Its inner valve spring was touching the center spring. The exhaust valve was in good condition; its inner valve spring was touching the center spring. The valve adjustment followers were loose in the rockers. The cylinder wall was OK; the exhaust seat was black and the intake seat bright. Both connecting rod nuts had lost torque. The piston was OK, but both oil rings were installed upside-down. The upper oil ring was worn at its end (tension fatigue). Roller marks on the cams indicated the rocker arms were not centered. The upper crankcase was cracked at the long bolt holes. Valve timing was as follows: intake opened 13° BTC; exhaust closed 9° ATC; intake closed 43° ABC; exhaust opened 60° BBC. Intake clearance was 0.036" and exhaust clearance was 0.038".
12 – 15 Dec 1932. The engine was rebuilt with the following revised valve timing: intake opened 13° BTC; exhaust closed 132° ATC; intake closed 47° ABC; exhaust opened 65° BBC. Intake and exhaust valve clearances were 0.036". The engine was run in up to 2,700 rpm and a neon tube stroboscope installed to observe valve gear operation. No valve bounce was observed up to 3,025 rpm. During a 5-hr run at 2,800 – 2,900 rpm the engine clattered above 2,800 rpm. After 2:20 hrs, BG 157 spark plugs were installed and the fuel changed from 84 octane to AC 1933 fuel. A tear-down inspection revealed that the valve gear was in good condition, although the 160-lb springs were touching between coils and between springs. The valves were ground and 200-lb springs and retainers installed. The cams, rocker arms, cylinder and piston were OK, but the lower oil ring was broken. A 6.0:1 compression ratio piston without valve relief cutouts was installed.
16 – 20 Dec 1932. The new piston was run in and endurance running commenced. Three venturis (1.438", 1.688", and 1.938") were tried to get good part-throttle performance with minimum wide-open throttle restriction. The engine was torn down for inspection, which revealed that the outer and middle valve springs were touching. The rocker arms, cylinder and piston were OK. The exhaust seat was rough and the oil rings were worn so that both the upper and lower edges were touching the cylinder.
21 – 27 Dec 1932. The engine was rebuilt, valves were ground and the oil hole between cam lobes was enlarged to #50 (0.070"). The engine was run from 2,000 – 3,000 rpm at 10 inHgA boost and at 2,500 rpm at 20 inHgA boost with 250° Prestone-out temperature. When running a curve with 10 inHgA boost from 2,500 to 3,000 rpm, a big bmep drop was noted between 2,700 and 2,800 rpm; further runs were limited to 2,700 rpm, which with 20 inHgA boost showed 245.1 psi bmep. A check on previous friction-run data with Prestone-out temperature of 232°F and 180°F. Increased boost to 28 inHgA using AC 1933 fuel with 4cc/gal TEL. A power loss still occurred between 2,700 and 2,800 rpm, a 14 psi bmep drop. A flash reading at 30 inHgA boost was stopped by preignition. The BG 157 spark plugs were replaced by AC 1½. The engine was run for about 8 min at 30 inHgA and 2,700 rpm; it showed a 296 psi bmep and 0.645 lb/hp/hr fuel consumption. There was heavy detonation but no sign of preignition.
The engine was torn down for inspection, which revealed the valves, rocker arms, cylinder to be serviceable. The flywheel was loose on the crankshaft due to a loose retaining nut; the crankshaft inner cone was worn. An oil ring was cracked.
28 – 31 Dec 1932. The valves were ground, an indicator hole tapped into the cylinder head, and valve reliefs machined into the piston head. The crankshaft inner cone was repaired with a case-hardened cone. Oil pressure was increased by blocking the pressure relief bypass and auxiliary oil relief passages. The engine was reassembled and fitted with indicator drive parts.
4 – Jan 1933. Several indicator cards were run at 2,700 and 2,800 rpm and 20 inHgA. A spark plug porcelain cracked and went through the engine; the cylinder was removed for inspection and a tachometer drive fitted to the camshaft when it was reassembled. Curve were run at 2,700 rpm and 0 to 30 inHgA boost.
17 – 20 Jan 1933. Friction runs at 2,000, 2,500 and 3,000 rpm were made. Distorted piston ring lands allowed excessive blow-by after running at 2,000 rpm and 250 psi bmep for 1 hr. The cylinder was disassembled for inspection. While the valves and rocker arms were OK, the cylinder wall was picking up aluminum from the piston and the piston was scored by cylinder contact. The piston pin hole was scored and the piston rings had lost their tension. The connecting rod small-end bushing was loose in the rod and the upper Babbitt bearing was cracked.
21 Jan – 2 Mar 1933. The cylinder wall was cleaned up by hand, a new piston machined with the skirt clearance increased from 0.022" to 0.030". The connecting rod bronze bushing was replaced and the cracked upper connecting rod Babbitt bearing was replaced by one made from lead-bronze; an oil squirt hole was drilled in the rod. Hammered-style rings were ordered, but while waiting for them to arrive, test engineers ran in the new piston with standard rings. On 26 Jan 1933, the engine was demonstrated to S.D. Heron. When the hammered rings arrived, the run-in continued until 35 minutes at 3,000 rpm and 250 psi bmep was achieved. After a total endurance time of 8:04 hrs the exhaust rocker box broke at the rocker pin. (NOTE: Hammered piston rings introduced tension into the ring by hammering the inside, which created an outward radial pressure against the cylinder when the ring was installed; Albert Wenzel developed a ring-hammering machine around 1912. )

[DuBois, R.N. Report of Performance and Endurance Test of Continental "Hyper" Engine No. 1 (Detroit, Michigan: Continental Aircraft Engine Co.) 6 Feb 1933.]

10 Apr 1933. Continental Vice President and General Manager Ray S. Deering wrote PPL civilian engineer Robert Insley informing him that Continental Chief Engineer Norman. N. Tilley had requested a cost estimate for an additional Hyper Cylinder. This item was essentially a duplicate of the two Continental had already produced for the USAAC, except that the head and barrel coolant jackets were to be smaller. Only the bare cylinder studding assembly, with coolant connections, studs, valve seats and guides was to be supplied. The engineering, core box changes, materials, purchased finished parts, labor and shop overhead would cost 986.94; no administrative overhead was included, as the USAAC was anxious to begin testing.[10 Apr 1933 letter, Deering to Insley, author's collection.]

26 Jul 1933. Acting Aircraft Branch Chief Capt H.Z. Bogert issued Memorandum Report AD-51-126 Addendum 1, reporting on a study of XO-1430 mounting. The engine appeared to be easily adaptable for wing mounting as shown on drawing S34X17 (not found). The engine and its cowling to provide satisfactory accessibility required a leading edge notch about 80" deep, with the front spar aft 20% of the 150" wing chord and the propeller 33% ahead of the leading edge. If nose box-beam wing construction with the rear face at approximately 30% chord was contemplated, a new structural problem would arise, but it might be possible to provide strength and rigidity by building a box of equivalent strength aft of the nose box spar. Another installation study was to be made with a two-stage supercharger.[USNARA RG342 RD1670, 502-2-108 O-1430 to 340630. 8]

5 Aug 1933. USAAC Procurement Section Chief Maj H.A. Strauss wrote Continental regarding the 1,000 hp, 1,425 in³ displacement opposed type engine.

1. The following proposal for continuing work on the high-speed, 12-cylinder, opposed type, liquid-cooled engine is submitted for your consideration and comment. The work to date has been in the form of single-cylinder testing and design studies to determine the feasibility of a 1,000 hp opposed engine type and to determine whether a cylinder could be developed that would permit obtaining 1,000 hp at 3,000 rpm with a displacement of 1,425 in³ The USAAC has closely followed the cylinder design and testing and the multi-cylinder engine design studies. This project has now reached the point where it is desired that your company accept full and complete responsibility for the design, construction and test of the multi-cylinder engine, with the USAC acting only in an advisory capacity. If the Continental Aircraft Engine Company is interested in undertaking this development, it is desired that estimates of costs be furnished on each of the following phases with a breakdown of the quotation at several logical points in each phase. In making these estimates the following project divisions should be observed:

First Phase (A) The contractor will construct a new single cylinder with the head made of any material that he considers satisfactory, with a one-piece water jacket, and any other changes considered desirable as a result of the previous single-cylinder testing, and conduct sufficient performance and endurance tests to determine that the work in the subsequent phases can be satisfactorily accomplished. Any failure of the Government-loaned test engine shall be repaired by the contractor, without obligation to the Government, but with USAAC approval of the repair method. Complete detail and assembly drawings, bills of material and parts lists of the 1,000 hp, 12-cylinder opposed, liquid-cooled, geared engine will be made and one set of Vandykes (reproducible blueprints) of the above will be furnished to the Government. In the design of the 12-cylinder engine, the following requirements will apply:

The current edition of the Handbook of Instructions for Airplane Designers shall be followed.
All material shall comply with the contractor's material specifications, U.S. Army or Navy specifications, where they are applicable; the use of other material will not be permitted without written USAAC approval.
Workmanship and finish shall be in accordance with high-grade aircraft engine practice.
Provision shall be made for driving two independent tachometers with clearance being provided at one of the drives for installation of an electric tachometer, requiring a minimum clearance of 3.5" diameter x 5" depth. This requires two tachometer takeoffs, and this requirement cannot be met by the use of an adapter with two outlets.
The contractor shall provide for installation of the following equipment:
1. Starter in accordance with Figure 2 and Air Corps Drawing 0150977 or 074987, except that eight studs shall be used to permit reversing the engine rotation direction. The use of internal splines shown on Figure 2 is optional with the contractor. If the spline is furnished, it shall conform to the dimensions shown in Figure 2.
2. Generator in accordance with Figures 3 and 4. The generator shall rotate at crankshaft speed.
3. Two (2) gun synchronizers, Type E-4, rotating at propeller speed; provisions shall be made to permit the use of Type E-1B solenoid control, Air Corps Drawing 30-145.
4. Type C-5, Type F-4 or Type F-6 fuel pump.
5. Vacuum pump for operating air driven instruments, in accordance with Figures 5 to 7; the vacuum pump drive shall rotate at not less than 1.10 of more than 1.25 times crankshaft speed.
6. Fuel charger drive for Marvel-Chandler fuel charger, to operate at 0.5 crankshaft speed.
The contractor shall furnish and install the following equipment:
1. Bendix-Stromberg suction type carburetor.
2. Shielded BG or H-T spark plugs.
3. Copper-asbestos spark plug gaskets of the size specified in U.S. Army Specification 95-28017.
4. Exhaust pipe flanges, which may be of stainless steel.
5. Scintilla SC-D magnetos.
6. Scintilla 12-cylinder distributors.
7. Radio Shielding, subject to the approval of the USAAC prior to engine construction; shielded spark plugs with a maximum overall length, as measured from the gasket seat, of 2.25", and a maximum shield diameter of 2" shall be used, and the spark plugs shall have a terminal with 11/16-24 USS thread.
Cover plates for covering the drive openings for the starter, generator, vacuum pump, tachometers, synchronizers, fuel pump and fuel charger shall be supplied with the engine.
Ignition cables of 0.295" diameter except from the magneto to the distributor, which shall be 0.360" diameter, in accordance with U.S. Army Specification No. 95-28004, shall be furnished on the engine; A sample shall be submitted by the contractor for USAAC approval prior to engine construction, and the ignition cable to be used on this engine shall be procured from sources approved by the USAAC.
The propeller shaft end shall conform to the requirements for the No. 50 shaft, Figure 1.
The engine shall be furnished without propeller hub, but front cone, Air Corps Drawing No. 31-395, snap ring, Air Corps drawing No. 31-294, retaining nut, Air Corps Drawing No. 33B4679, rear cone, Air Corps Drawing No. 31-2444, rear cone spacer, Air Corps Drawing No. 33B3502, clevis pin, AN Drawing No. 394-15, cotter pin AN Drawing 380-2-2, and washer, AN Drawing 960-416, which are the attaching parts, shall be furnished.
The lubricating system shall be arranged to show pressure at idling speeds. The oil pressure adjustment shall be readily accessible when the oil lines are installed, externally of the engine while the engine is running and without disassembling the valve.
The scavenging pump shall be of sufficient capacity to enable the engine to be idled for extended periods without oil loss through the breather or accessory drives, and without excessive oil accumulation in the crankcase; oil leakage through the accessory drives shall also be prevented by other necessary provisions.
A Cuno oil filter shall be installed in the pressure line between the pressure pump discharge and the manifold supplying oil to the main bearings; the oil bypassed by the Cuno filter shall not carry the accumulated dirt to main bearings, and oil flow through the Cuno filter shall be from the outside to the inside.
The oil system shall be so arranged that oil from a supply tank, when placed not more than 20" above the oil inlet, will not accumulate in the crankcase when the engine is not in operation.
Oil inlet and outlet connections shall be 1" female pipe threads with a clearance provided for turning elbows, in accordance with Air Corps Drawing No.750-16, with all accessories installed.
The oil inlet connection to the oil pressure pump shall not be above the oil pressure pump outlet; no trap shall exist at the oil pump inlet.
Provisions shall be made for venting the oil tank at both the front and rear ends of the engine; these connections shall be 3/8" pipe tap openings and be located in the engine upper half and so arranged that the passages are radial from the crankshaft center line; the oil inlet, oil outlet and oil tank vent connections shall be bolted on flanges incorporating pipe threads.
Provision shall be made so that scavenged oil from the engine front section is returned immediately to the scavenging line without passing through a second scavenging pump.
Oil bypassed from the pressure system shall be returned to the pressure pump inlet and not into the scavenging system.
Provision for the measurement of oil and coolant temperatures will not be necessary.
Flexible metal hose shall not be used on this engine.
When hose connections 0.75" in diameter or less are used in the fuel and/or cooling systems on this engine, liners, Part No. AN-875 shall be used.
The coolant outlet temperature variation shall not be more than 3°F between right and left cylinder blocks when operating at rated power and rated speed with a cooling medium outlet temperature of 250°F.
The engine shall be so designed that Z-plates similar to those shown in the report on "The Design of the 1,000 hp Flat Engine with Hyper No. 2 Liquid-Cooled Cylinder", dated 22 Jun 1933, may be installed; the method used for installing these plates shall be submitted to the USAAC for approval prior to construction of the cylinders.
The weight of the engine, complete, without Z-plates for mounting, shall not exceed 1,085 lb; this weight is based on a complete engine, the definition of which is covered by Section VI, Part I of the current issue of The Handbook of Instructions for Airplane Designers.
The reduction gear ratio shall be 2:1.
The engine shall be constructed so that the direction of rotation may be reversed in a manner described in the report on "The Design of the 1,000 hp Flat Engine with Hyper No. 2 Liquid-Cooled Cylinder", dated 22 Jun 1933.
Provision shall be made to seal the fuel pump drive against leakage of oil from the inside of the gear case.
The fuel pump drive adapter pad shall be provided with six tapped holes for receiving attaching studs or cap screws in accordance with Air Corps Drawing S34A1753.

Second Phase (B) The contractor will construct a 12-cylinder engine in accordance with the drawings and requirements covered by the first phase. This engine will have a General Electric designed geared supercharger, which will be furnished by the contractor.

Third Phase (C) The Contractor will conduct a development test in accordance with the current issue of Air Corps Specification 28144, at an actual horsepower of not less than 1,000 and at a speed not less than 2,800 rpm.

2. For all the phases covered by Paragraphs 1A, B, and CS, the Government will require the following:

The right to drop the project at the completion of any phase, or part thereof, at the option of the Government and no phase shall be undertaken until formal approval has been by the Government for the last phase completed and the next phase formally released.
The contractor shall agree to grant, sell and convey to the Government for the consideration of $1.00, the non-exclusive, irrevocable right and license to make, have made, use or sell for Government purposes, any and all engines, cylinder designs or parts hereinbefore mentioned and described and to practice or cause to be practiced any and all discoveries, inventions, improvements and/or suggestions that have been or may be made, perfected or devised by the contractor, his representatives, employees, or other cooperators in connection with or incident to, or in any manner used in the construction of the articles herein referred to, of the design thereof, under any and all patent or other rights based upon such discoveries, inventions, improvements and suggestions; the right and license herein conveyed shall extend throughout the United States, its territories and all foreign countries, and shall remain in full force and effect during the term of patent and/or other rights now held or subsequently acquired by the contractor and relating to the articles herein referred to or modification thereof.
The contractor will hold and save the Government, its officers, agents, servants and employees harmless from liability of any nature or kind, including cost and expense for or on account of any patented or unpatented invention, article or appliance manufactured or used in the construction of this engine, engines or engine parts, when manufactured by or for the Government by the Continental Aircraft Engine Company or any other company.
All major assembly and installation drawings shall be approved by the Government, but the approval of any design is not to be interpreted that the Government assumes responsibility for proper functioning or is not to imply acceptance by the Government thereof.
Reports will be submitted every two weeks, including blueprints of layout drawings and major assemblies, and copies of all reports such as bearing analyses and test reports, as soon as practicable after the completion of the work to be covered by the report.
Partial payments will be made at the satisfactory completion of each phase, or part thereof, on which quotation has been submitted by the contractor for which formal procurement authority shall have been initiated.

3. The Government will cooperate, as far as practicable, in the inspection and advice concerning the engine or engine parts during the process of fabrication and/or construction. Inspection personnel will act in an advisory capacity only and will not be authorized to reject material or fabricated parts; they, however, will call to the attention of the contractor for his consideration, such materials as are not in accordance with U.S. Army Specifications, unsatisfactory workmanship, and practices and processes not in accordance with Government standard requirements.

4. It is further requested that an estimate of the time required to complete each of the three phases, or parts thereof on which quotations are submitted.

18 Aug 1933. Engineering Section Chief Maj C.W. Howard wrote Continental regarding their letters of 26 and 27 Jul 1933 regarding Purchase Order 33-3804 – Endurance Test of Hyper Cylinder No. 2. In their letters, Continental had mentioned using a solid exhaust pipe connected to the cylinder flange and subsequent breakage of cylinder flanges and studs during endurance running. The Engineering Section had encountered poor results with solid exhaust pipe connections, suggested that the cylinder failure at 49.95 hrs may have resulted from the solid pipe, and that future running should employ a more flexible arrangement. While flexible tubing had also been unsatisfactory, short exhaust stacks that telescoped into another pipe had worked well. The stack entered the pipe at about 3" and the joint was covered by a woven asbestos tape that was wired in place. A boss welded to the exhaust stack near the flange and a small jet of water was injected into the exhaust stack after the engine was running.[18 Aug 1933 letter, Howard to Continental, author's collection.]

These figures were all based on 950 fps propeller tip velocity. This study indicated that three propeller reduction ratios (5:3, 2:1 and 5:2) should be designed. N.N. Tilley questioned whether a spacer should be used between the propeller cone and thrust nut; the Propeller Unit thought this necessary because of the different hub lengths of fixed- and controllable-pitch propellers. The Installations Unit opined that coarse screens should not be used in the oil pump oil-in lines because they would restrict cold oil flow; such screens were desirable in the oil scavenging system.[USNARA RG342 RD1670, 502-2-108 O-1430 to 340630. 9]

9 Sep 1933. Ford Prescott released Memorandum Report E-57-126 (Again! They needed to assign unique report serial numbers!) covering a conference at Wright Field on 22 Aug 1933 on the 1,000 hp Engine attended by R.L. Long, N.N. Tilley and C.N. Furay of Continental and Division representatives. (NOTE: Although the release date is out of order, the subject matter belongs here. Also, this conference was an obvious prelude to the larger 5.500" bore, 5.000" stroke, 118.75 in³ displacement (1,426.5 in³ 12-cylinder) Hyper No. 2 cylinder.)

The engine's weight was discussed, including the impact of the proposed long nose, gun and tachometer drives. Chenoweth stated that the total weight must not exceed 1,120 lb, which, allowing 0.28 lb/hp for the cooling system, a 1,400 lb installed weight; this was intended to be competitive with air-cooled installations. The calibration and endurance tests should include reduction gearing as these gearing losses were undetermined. Cams for single-cylinder testing of the new setup were left to Continental's discretion. Tilley proposed to check whether the oil jet directed at the piston crown was really necessary since the multi-cylinder engine with its larger and less restrictive bearings would throw more oil. Detailed test requirements were tabled for a later date to allow discussion of other points that needed immediate attention. Continental thought the front gun synchronizer drive would unnecessarily complicate the engine and increase its weight; only the rear synchronizer drive would be included. The interference of the electric tachometer solenoid with the second tachometer drive was deemed unimportant since a mechanical tachometer would not be used with the electrical type on the same engine. Continental was to select the Cuno oil filter size in concert with the manufacturer. Continental's objections to 1" pipe threads for oil connections were overruled because they had provided good service. Oil packing on the tachometer drives was mandatory as this would prevent oil from seeping through the flexible shaft and into the tachometer.

The desired 2" diameter x 2.25" high space for shielded spark plugs was deemed impossible, since the cylinders had been designed to accommodate the BG and MT high-tension shielded plugs originally specified for the cylinder. The longest spark plug lead was about 60", which meant that Packard shielded cable was acceptable; it was agreed that laboratory tests would be made before a final decision. There was considerable discussion about whether the Scintilla double magneto could be reversed in the field and about various schemes to do so; no conclusion was reached. A type F-6 fuel pump driven at propeller speed was indicated and had a 300 gph flow at 1,700 rpm.

Continental objected to proposed standard vacuum pump drive because the small shear member might give trouble in the winter when oil was viscous (this was before dry-air pumps). The USAAC had based large procurements on pumps with standard drives and desired to stick with that design. Continental's main objection was the mounting pad height required by the wet pump drive member.

The team decided to lay out a bevel gear drive from an exhaust-driven turbine through a vertical shaft to be a modified blower mounted on the engine rear. This would probably call for a special blower in view of the need for an intercooler between the blower and engine. The weight would be increased over a combined turbine and blower mounted below the engine, since in this case the geared blower would be omitted from the engine, and the drive from turbine to blower would be lighter and simpler. Objections arose to the experimental nature of the high-speed bevel gear drives, along with removal of blower inertia fro the accessory drives at the crankshaft rear, a condition that would impose severe torsional stresses on the magneto, generator and fuel pump drives. The present drive was through a spring coupling like those used in radial engines that would not function without the supercharger inertia load.

A question arose over payment for the 50-hr test that had terminated at 49.05 hrs. Lt Powers stated that the only settlement possible under the circumstances was for Continental to invoice the USAAC for 49.0833 / 50 of the amount agreed for this test. Long pointed out that 11 hrs had previously been run on Cylinder No. 1, but Lt Powers stated that this could not be taken into consideration under existing regulations.

Continental wondered whether the USAAC would consider a cost-plus basis for construction of the 12-cylinder engine, in view of the necessity of covering unforeseen contingencies in an experimental contract; this topic was tabled for later discussion. Continental also objected to the minutely detailed specification, but it was pointed out that these removed uncertainties, basing estimates on definite requirements.[USNARA RG342 RD1670, 502-2-108 O-1430 to 340630. 11 – 013]

19 Sep 1933. Continental responded to the USAAC's 5 Aug 1933 1,000 hp, 1,425 in³ displacement opposed type engine specification with a letter proposal from Sales Manager Ray Long to MatCmd. Apparently there had been two conferences regarding this on7 and 16 Sep 1933. Following up on suggestions made during the conferences, Long recommended that the project be divided into four major phases, each with subdivisions as applicable.

Phase No. 2 was the completion of detail and assembly drawings, bills of material and parts lists of the 1,000 hp 12-cylinder opposed liquid-cooled geared engine, of which one set of Vandykes was to be furnished to the Government. This engine design was to meet the requirements of the 5 Aug 1933 letter, with certain alterations and additions already discussed and agreed upon between Continental and USAAC engineers. This phase was priced at $16,770.17.

Continental estimated that Phases 1 and 2 could be completed in 180 calendar days from the date of contract. To further expedite progress, Continental had already released the necessary pattern changes and proposed to carry on without further delay in advance of formal USAAC authority.

Long estimated that Phase 3 could be completed within 130 calendar days after starting work thereon. He estimated 100 days if only Sections a and b were authorized. Phase No. 3 could be started within 60 days of Phase 2 start.

Phase No. 4 covered development test in accordance with the current issue of Air Corps Specification No. 28144, at an actual output of not less than 1,000 hp and a speed of not less than 2,800 rpm.

In view of the UASSC's inability to commit at that time to the Phase No. 4, Long did not submit pricing, but voiced Continental's willingness to complete the project on a cost no-profit basis if and when USAAC was in the position to authorize such work.

Payment for each Phase and/or Section was to be made upon completion and acceptance thereof and was not to be contingent upon the completion or acceptance of any other Phase or Section. In view of the fact that the prices were based on conditions at the time of quote, long reserved the right to revise any portion of the quotation on which formal inquiry was not received from the Government within 30 days from date. However, it was understood that any change in quotation was to be based on later material and labor fluctuation from then-current costs at the time of acceptance. [19 Sep 1933 letter, Long to MatCmd, author's collection.]

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P02Fig002	P02Fig003	P02Fig004	P02Fig005	P02Fig006	P02Fig007

		Continental began work on XO-1430 Hyper No. 1 cylinders during 1932 and by early December was testing one. Coverage of this early work, along with any pertinent correspondence appears to be missing. As previously discussed, Continental's role was limited to routine design engineering, along with test engine construction and testing. However, the photographs and diagrams in the first Continental report indicate that considerable work was done.
High-Speed Single-Cylinder Test Engine Mechanism (Continental)


P02Fig001. Test Setup