Speed Record Machine
To develop and build a Helicopter that will be fast enough to challenge the World Speed Record with simple/inexpensive components.
The ported OS 46FX is installed.
Carburetor is the SuperTiger .90 size. The body was machined to fit the OS crankcase. The intake sleeve was removed for more airflow.
The tuned pipe is a .40 size V-Tech with a Jayson Products/Johnson header (Arizona, USA).
Fuel: Five percent Klotz nitromethane + 18% Klotz KL-100 or KL-200 oil + 77% pure methanol = 100%
Main Rotor Blades are carbon NHP 550mm X 47mm. Update!! Now experimenting with many other blades on a dyno.
Pitch range with full power applied is +15 degrees to -15 degrees. Total range is 30 degrees.
Mainshaft is from an older Shuttle. It is about 24mm longer than the stock ZX, to handle all of the extra pitch.
The 46FX sleeve on the right is not ported. The 40SF sleeve on the left has
just the exhaust ported.
This is the Shuttle using stock sideframes.
Here are the servos and linkage.
It really is only an old airplane OS 40SF motor.
It really is only an airplane OS 46FX motor.
Here is the real speed secret. A fly trapped inside the blade during molding.
April 5, 1999:
April 16, 1999:
As it turns out, both of the clutch pinion bearings were being over compressed by the side frames. Hard to believe for stock ZXX side frames. New bearings did not cure it either. I thought it was engine/clutch misaligment the whole time. So I ended up puting a .009" shim in between the frames next to the lower bearing, to reduce the compression forces on the bearing. Then it had to be epoxied into place. The upper bearing had the same problem. When the sideframes screws were tightened, it would make the lower bearing very rough. So I relieved the sides of the bearing block about .030" and that solved the upper bearing over compression. The power increased due to the reduced drivetrain drag. Now the Shuttle is pulling 15 degrees at full power with stock semi wood blades!! The engine is much smoother at full throttle too!!
The 25 new neoprene belts from Stock Drive Products have arrived. They seem to work ok for standard useage.
Last year the big problem was getting the flutter out of the rotor system as I would tilt the Shuttle up onto the front of it's landing gear to prepare for a launch during drag racing. The blades would flutter so violently that I could not launch that way, thus not leaving the ground as fast as possible. I removed the swashplate a few months ago. It has had a rough bearing for a long time, but it never had any slop in it. So I replaced it with one of those dual bearing swashplates from Quick of Japan. What a difference. The flutter is completely gone!!!
Now I have been practicing drag race launches with fantastic success. I tilt the heli up until the nose of the canopy nearly touches the ground!!! More practice should make me more competitive this year.
The only lasting problem that is tough to fix is the stock tail rotor drive system does not last very long. The stock belts and pulleys still wear out too fast and cause a bad vertical tail rotor oscillation....
June 8, 2000:
The other night I noticed that when the boom strut clamp on the tail boom is not screwed tight to the boom, that the tail rotor does not shake. When I tightened the clamp, the vertical tail rotor shake returns. I've done this twice on two seperate flying sessions, and the clamp consistantly changes how much the tail vibrates. I may try using longer boom support struts to see if that changes anything. Or maybe some kind of vibration isolation. The clamp is something I made on a mill out of Delrin. It wraps around the boom completely and uses only one bolt to hold both struts and to firmly clamp the boom.
The tail rotor belt and pulleys from the Shuttle RG have a lot less drive train drag than the stock Shuttle belt. The teeth on the belt are much finer and smaller than the stock belt. I am impressed with the clutch pulley and the tail rotor pulleys both being made from aluminum. The clutch pulley did require green Loctite to keep it from clicking like the plastic ones do if they become loose on the shaft. That means it's going to be difficult to remove if the occasion arrises. Even though the belt is tighter than I usually run a stock belt, it is very smooth. The belt, two pulleys, and the shaft ran $107 USD at Rick's in Texas. When the Shuttle is going upward at about a 45 degree angle at 15 degrees of pitch, the RG belt definitlely bogs down the engine less, and keeps the rotor RPM up a little higher. The other thing I noticed is that as soon as I land, the tail rotor pulley and the belt are cool to the touch. The stock belt runs quite a bit warmer. It will be interesting to see how well it holds up, especially this weekend at the Reno Rotary Rendezvous.
There was some flutter in the main blades the other day. I found a couple of sloppy links controlling the flybar. New links seemed to cure the fluttering.
June 9-11, 2000:
The Reno Rotary Rendezvous was great. Curtis Youngblood is great to talk to and an excellent, smooth pilot to watch. He kindly autographed two tee shirts for me.
The Shuttle has a bad vertical shake. I took off the tracking tape from the NHP blades and left the strut rod boom clamp loose. That took care of the shaking. I bought some long carbon boom struts to try and see if they will allow a fully tight clamp.
The RG tail rotor belt and pulleys held up great. The system was smooth from the first flight to the last. I did have to run the belt fairly tight to keep the tail from moving back and forth. Even with a tight belt the RG system is extremely drag free and smooth. No signs of premature wear.
The brand new tail rotor pitch plate broke to just one of the tail rotor blades during a test flight. It was pirouetting about half the maximum speed that it is capable of. So I auto rotated over my girlfriend and into the dirt next to the parked cars. What a save!!
The drag racing was unexpectedly moved from Sunday morning to Saturday afternoon. So I had to fix the shaking and fast charge the 800 mah racing pack in an hour. I was third place out of 4 racers in the 60 class with the Shuttle. The video tape of my launches show that I'm keeping it close to the ground. In fact, I hit the ground one time during a race. Reno is at about 5000 ft, so power and cyclic response was down. I raced using 15% nitro fuel rather than the 5% that I've used for years. It had a tiny bit more power and the mixture range was leaner overall. I tried hard to get Curtis Youngblood to race, but him and a few other top pilots did not want to participate.
My girlfriend and I won about $260 in raffle prizes. The world record was set with 20 pilots hovering their machines inverted at the same time for 60 seconds. Eric, the 21st pilot, had a flat tire on the way to the field, so he could not make it in time. It was awesome to see all of those machines inverted!!!
Curtis mentioned that he may have a 46 version of his Muscle Pipe available inside of a year. His JR Vigor was very quiet with the Muscle Pipe. He said that it added about 1/2 horsepower to a 2hp 60 engine.
August 13, 2000:
The Bayside meet was well done this year as always. Lots of familiar faces. The Shuttle was particularly powerful this time. The new RG belt and pulley upgrade is working to perfection. The tail rotor is smoooooth and has very little drag!! I made a test flight before the races and everything was perfect. I had to trim the tail rotor mix a bit. It was pulling a full 15 degrees of pitch with ease on 15% nitro this time.
On the first heat, I tilted the Shuttle up on the front of the landing gear with the nose of the canopy nearly touching the ground. Then the blades started to flutter very hard. I came off the throttle quickly and then the canopy fell off. I pushed the canopy back on and was allowed to restart the race. On the second attemp, the Shuttle started fluttering again. This time I just went to full collective to launch it. The Shuttle went forward about 5 feet and then it was as if it went to zero pitch. There was no more forward thrust. Because the heli was up at 90 degrees to the ground, there was no lift to hold it up, so the blades dug into the runway and just disintegrated!! So much for my trusty NHP's!! Carbon blade parts went flying through the air!! Nobody was hurt. I shut the engine off right away.
The post mortum inspection found that the collective lever that attaches to the collective servo, had broken in half. So the rotor head had no collective control at all. I guess a couple years of racing had fatigued the aluminum lever so much that it finally failed. Too bad, this was the first time that I had no tail rotor vibration and had very little to prepare for before the race. I was third out of three. The feathering spindle was replaced. I straightened the mainshaft and flybar rod. It's back together two days later and running smoothly. I'll be ready for Sacramento!!
October 6 & 7, 2000:
The Sacramento meet at SVRW club was awesome!! I took first place in the 46 class and in the 60 class!! The upgraded tail rotor drive belt was working flawlessly as it has this whole year!! The only mysterious problem was that there was a strong, unexplained vibration that shook the entire helicopter. During the inspection for the vibration, Ron Bodwell (Thanks Ron!!) came over to my heli and spun the rotor head around and found that the main shaft was severely bent!! I have no idea how this happened. A fresh mainshaft took care of the problem. At high rpm the Shuttle was smooth again. The main blade tracking was found to be about 1/2 inch off. That proved that the previous mainshaft was bent. There was absolutley no blade flutter this weekend!! There were a couple of ball links that had a bit of slop in them in the rotor head that were replaced.
It seemed to me that during full vertical acceleration, the engine was not bogging down in the least. So I added a little more collective pitch via the linkage. The radio was already at 100% travel. I had to keep adding collective pitch until I finally got the engine to bog slightly at full throttle. On the bench, the pitch gauge was now reading an astounding 17.75 degrees!! The Shuttle now had a greatly improved vertical acceleration. Some of the guys I showed the pitch gauge to asked if I really thought the measurement was real. I could not explain the extra 2.75 degrees of pitch that I was measuring. Ironically, during a demo drag race on Saturday, Charlie Rice beat me soundly 3 out of 3 races. The extra 2.75 degrees of pitch contributed greatly to my beating Charlie and the other participants in the drag racing on Sunday. For the past 10 years I have only used my home brewed five percent nitro fuel. These races I used 5% during the 46 class and 15% durin!
g the 60 class racing. The only real difference is that the engine ran a bit leaner with the 15% nitro. But seemed to add a little extra power. Off the line, the Shuttle had awesome acceleration this year. The top speed needs some improvement. Maybe an aerodynamic canopy would help.
The main contributing factors for success were the significantly reduced drag and superior operation of the tail rotor belt and pulleys, no vibration in anything, lengthening the pipe by .375 inches, and pilot launch training. I will definitely be researching and verifying the 17.75 degrees of pitch to make sure that it's real. Adding or subtracting pitch does have a pronounced effect on the rpm and acceleration. So I think that the 17.75 degrees may be authentic. If it is, then I am well on the way to my goal of 20 degrees!! The Shuttle had a new set of NHP 550's for this weekend.