Propeller Dynamics Essential reading for model aircraft contest fliers. This is the only book on the market explaining propeller theory in non-mathematical terms. A rattling good read, I know, I wrote it. Read more...

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Monday September 9:

Good news at the Dago Red camp. After an incredible non-stop thrash Dago Red was test flown by Skip Holm early in the morning. At the conclusion of the test flight Skip put the aircraft into a terminal velocity dive. When asked; 'how fast', the response was; 'you don't want to know..!!' It should be pointed out that at one time I asked Bill Kerchenfaut how long he'd been up. He couldn't remember exactly but it was over 30 hours. After breathing a sigh of relief, the Dago Red team could get some well-deserved rest. In official practice Skip did a 488 mph lap with lots more speed available. Then Skip shocked all in attendance when he screeched around the course at an average speed of 497.8 mph, the fastest official lap ever at Reno.

Pete Law attended to his customers by tweaking their ADI systems. It's always a fine line as to how much ADI fluid is injected into the engine at race powers. Too much ADI fluid causes induction temperatures get too low resulting in poor fuel distribution and in a worst case scenario, fuel coming out of solution resulting in 'puddling' in the intake manifold. Too little ADI can have even more dire consequences; high induction temperatures which possibly leads to detonation. When ADI fluid is fed to an engine, the fuel flow needs to be reduced or 'deriched' to use the correct terminology. However, in the past this caused a problem with the Merlin powered aircraft. Due to the fact Merlins use updraft induction, G forces generated while navigating pylons would cause further derichment resulting in a lean condition and consequently sever back firing. Back firing of this magnitude would often time wreak havoc in the engine including blown up induction scoops. Therefore, for many years Merlin powered racers would not de-rich during the application of ADI. The resulting over-rich mixture cost horsepower ® lots of it. However salvation came in the form of a hydraulic device that senses G loads. Hydraulic fluid, under the influence of pylon G forces, pushes down on fuel pump diaphragm and therefore fools the fuel system into thinking it's operating at 1G.
 

Michael Brown with September Fury managed a 468 mph lap ® his fastest so far and the fastest a Sea Fury has circulated the pylons at Reno.

Check Mate gave every one a scare when the Aeroproducts propeller, modified from a Skyraider unit, suffered an oil leak and dumped all the propeller oil overboard. It should be remembered that, unlike a Hamilton Standard, the Aeroproducts propeller uses an independent oil system rather than relying on engine oil as would be the case with a Ham. Std . With total loss of oil the propeller instantly went into fine pitch due to the centrifugal turning moment. The resulting over speed created the most unearthly racket imaginable. Later reports put the over-speed at any where between 4,000 and 4,500 rpm and this was for an R-2800Ä!! Shirm Smoot made a skillful emergency landing rolling out with the engine shut down. After parking in its pit space the expectation was for a blown up engine to be revealed after the cowl was removed. Astonishingly, that was not the case, in fact the oil screens did not show any metal. This is an outstanding testament to Ray Anderson's engine building skills. The offending propeller was removed and the oil seal that created the problem was replaced. After replacing the prop, serous thought was given to flying the airplane again. After consultation with several knowledgeable experts, the Check Mate team reluctantly had to throw in the towel.

Voodoo was running well but high oil temp and low induction temp. persuaded the team to fit additional spray bars to the oil cooler. Problem is, with P-51 style dog house, spray bar water inevitably gets to the supercharger after cooler. It should be noted that engine was not a tube engine, i.e., it still retained the aftercooler.

Tuesday September 10:

Top news for Tuesday morning was the improved status of Rare Bear. It was run up to METO (maximum except take-off) power. However was felt that the propeller was pitched too coarsely, especially at idle, resulting in a lean condition as the R-3350 desperately tried to bite at the air. Many readers may know that Rare Bear has a unique three blade propeller. Using a Hamilton Standard three blade hub, blades from a Lockheed P3 Orion were adapted. Other things plagued the hard worked Rare Bear team such as fitting the cowl. Whenever an engine goes through a major overhaul cowl fitting is usually a problem.

The propeller pitch stops for Miss Trinidad were changed to give more pitch.

Bill Kerchenfaut being the most astute crew chief at Reno made the following observation to me on Tuesday morning: The only thing that is not negotiable at the Reno Air Races is time. You can get parts, you can get people, you can get money but you can't get more time and if you squander your time you cut your chances. With this priceless piece of philosophy in mind, it was surprising to see Strega's strategy of not flying on Monday. However, this top contender for the unlimited Gold Race was wheeled out Tuesday for a qualifying run. The buzz in the pits was that they would attempt to one-up Dago Red and go for a 500mph lap. A hush descended upon the course as Bill Destafani took off and warmed up to his qualifying lap. Emitting a similar ear piercing screech that Dago Red produced, all appeared well until the final lap approaching the home pylon when things started to come unraveled. The instant Destafani crossed the finish line the over stressed Merlin let go in a big way. Debris was seen flying off the aircraft as Destafani pulled up in order to trade air speed for altitude. Being one of the most experienced race pilots at Reno, Destafani executed a text book emergency dead-stick landing. The aircraft was immediately parked in a hanger rather than its usual place in the pits. A dejected Destafani was ready to throw in the towel. Even so, despite a blown up engine, Strega managed a 486.8mph qualifying lap. Cause of the blow-up was a lean condition that led to detonation quickly followed by a back fire. Damage to the engine was severe; a cracked supercharger housing, a failed blade connecting rod (#B5) and several violently detonated pistons including #A4 which was all but destroyed. Undoubtedly, other damage was incurred as well.

Wednesday, September 11:

The spirit of Reno came through to day when a number of folks from various teams, including Dago Red's, pitched in to help Bill Destafani get Strega racing again. Dan Martin had a race engine that he kindly offered to the Strega team. However, it was not in pristine condition, it had burned up a bank assembly several years before. Even so, Strega's team felt that between the two engines a good one could be assembled. As events unfolded, it was easier to simply repair the Dan Martin engine which required that the offending bank assembly be removed, a liner replaced and six new pistons installed.
 

Rare Bear performed more engine runs. Now the team was getting closer to submitting the aircraft for a technical inspection. Without the approval of the tech. inspectors, a race plane will not compete.

At 11:45 Brent Hisey flying Miss America suffered a catastrophic failure qualifying with the Rick Shanholtzer race engine. All the engine oil was pumped overboard which meant Hisey could not pull the prop back, in other words put it into course pitch to reduce drag. With fine pitch a propeller generates an inordinate amount of drag. Attempting an emergency landing on a dirt road, the aircraft spun around and ripped one landing gear off. Even after this major set back the Miss America team vowed to be at Reno next year with a totally rebuilt aircraft. Cause of the engine failure is open to conjecture. What is certain, the spin-on oil filter, which is a modification, was not attached. In a chicken and egg scenario it's not certain if a connecting rod that failed knocked the filter off, or; the filter canister coming off causing the rod to fail. Either way, a fresh rebuilt race engine was toast.

Sea Fury '911' powered by an R-3350-26W had been plagued with the problem of not de-riching. Notwithstanding various attempts at a fix, the problem had persisted all week. Not de-riching was costing upwards of 400 horsepower. Despite everything being checked nothing seemed to be out of place. The problem was eventually traced to the automatic boost controller, and the problem was fixed.

However, while qualifying, a high oil temperature was experienced.

After shut down a standard procedure is to check the oil screens. The presence of silver in the screen told the story, the master connecting rod bearing had been damaged causing an over temp of the oil. Only one thing to do and that was change out the engine. 911's team set to and embarked upon this major task.

Ike Enns flying a stock looking P-51D, 'Miracle Maker' in fact has a modified Merlin under the cowl. Initially disappointed with the airplane's performance, Pete Law recommended to Enns that he reduce the rpm from 3150 to 3000rpm in order to improve propeller efficiency. Although modified, its Merlin did not sport the preferable .420:1 ratio, instead it was running a .479:1 ratio. With the higher ratio, prop tip speeds become excessive. The only efficient way to increase the rpm of a race Merlin is to use 420 gearing. Just by reducing engine rpm by 150, speed was increased from 366 to 376mph. These speeds were attained at a slightly higher than stock manifold pressure of 70 in.Hg. and an induction temperature of 75 degrees C. This ideal induction temperature was due in small part to Pete Law's ADI system.