For a long time, I always wish to do a destructive test for the model engine, which to understand the life of the engine and the use of the gasoline engine's note. But it has been unable to do so due to time constraints.
At the beginning of this year; I started the model engine ultimate test with everybody’s help. To ensure the fairness of the trial, I decided to buy the gasoline engine and fuel from the market at random, I bought a brand of the XL25 engine (4.07 ml) in a uk online shop; and bought 30 barrels of synthetic fuel containing 30% nitro methane of a domestic brand in Beijing; and purchased a domestic brand Heat for 10pcs, imported a brand # 8 Miami Heat for 6pcs. After everything ready, I came to the outskirts of Beijing to start the model engine limit test.
The test procedure is as follows: Ground Engine Test procedure × × XL25 engine synthetic fuel test procedures:
1, using standard fuel (20% castor oil, 80% methanol) and 9 × 6APC paddle mill car 10 minutes.
(1) The medium speed for 5 minutes, then remove the engine for flushing.
(2) To mount on the engine, medium speed operation for 2 minutes; and then 3 minutes high-speed operation. Test the maximum speed record. Maximum speed tachometer highest reading in more than 10 consecutive seconds (same as below).
(3) To remove the engine for flushing.
2, To use 30% synthetic fuel for continuous running test.
(1) Medium speed operation for five minutes and then enters the high-speed operation, test the speed and record.
(2) Continuous high-speed operation for 4 hours. Check the engine and record.
(3) Continue 4 hours continuous high-speed operation. Check the engine and record.
(4) Every 4 hours continuous high-speed operation, until the engines abnormal.
(5) Each operation should test speed and record.
(6) Record total running time.
In more than 83 hours of continuous operation, I feel that the biggest challenge is the vibration of the engine, it is recommended that prior to use of the new engine, the first to conduct a comprehensive inspection, each bolt to be tightened; propeller static balance; muffler should use704 silicone seal and reinforcement; using high nitro methane content fuel, plus a 0.05 to 0.1 mm cylinder head gasket. After the above, I believe that there will be unintended consequences. The engine ultimate test is end, and I hope our work would achieve the effect forwarded.
The test was on the afternoon of Tuesday, March 6, firstly, I use the standard fuel grinding car and then continuous operation assistant synthetic fuel with 30% nitro methane. The maximum gasoline engine speed is 14000rpm, cylinder head Heat head surface temperature is 165 ° C. The sound of the gasoline engine is fine, with some vibration. Principle analysis, due to the new engine cylinder piston is very tight, fuel content of nitro methane is high, but generally the engine compression ratio is low nitro methane or without nitro methane fuel designed for use. So the engine sometimes may cause the pre-ignition, and to cause the vibration. The normal measure is to increase the cylinder pad of a 0.05 to 0.1 mm. Because we want is the ultimate test, so I didn’t do so.
To remove the cylinder head, found many pits on cylinder head and piston surface. Remove the cylinder and piston, many scratches on the side of the piston. Preliminary judgment that some granular foreign body inside the engine. Feeling crankshaft is still well-oiled, well-oiled between the connecting rod and the crank. Remove the crankshaft main bearing retainer pulverized about 10 mm, resulting in damage to the piston top and cylinder head. The engine continuous operated for 3 hours and 31 minutes this day.
The ultimate test of the gasoline engine completed, accumulated working time of 83 hours 10 minutes, the flight of 12 minutes in each of the ups and downs, the equivalent of flying 415 flights. Above experiment illustrates the domestic life of the engine is still very high, the domestic gasoline engine has made substantial progress, more than some foreign brand-name products in the service life; domestic synthetic fuel lubricating effect is already full beyond traditional castor oil, and has reached the international the level of the famous brand of synthetic fuel. This is indeed a good sign for the China model airplane enthusiasts.
Repaired for eight times due to gasoline engine failure parking during the test, the restructuring of the cylinder head bolts maximum workload. 3 of the Domestic Heat head damaged are all leak. Above inform that domestic engine reliability need to be improved. But honestly, the test conditions are really harsh, the engine is not designed to use high nitro methane fuel improvements (such as: plus cylinder head gasket, the use of "cold" Heat head), which can achieve such results really surprised me. Estimated that at current levels, if you use low-nitro methane synthetic fuel, its life is expected to be increased by 50% if used in conjunction with the the super lubricants repair fuel, engine life will improve exponentially.
No comments:
Post a Comment