Wonwings Diary-a blog with a difference. - Page 8

**wonwinglo** · 25-01-2006

Was I hearing things? I must be hallucinating. Then I looked up and saw a guy walking toward me, wearing a cowboy hat. A helicopter was idling a short distance behind him. If I had been at Edwards and told the search-and-rescue unit that I was going to bail out over the Rogers Dry Lake at a particular time of day, a crew couldn't have gotten to me as fast as that cowboy-pilot had.
The gentleman was Albert Mitchell, Jr., owner of a huge cattle ranch in northeastern New Mexico. I had landed about 1.5 mi. from his ranch house--and from a hangar for his two-place Hughes helicopter. Amazed to see him, I replied I was having a little trouble with my chute. He walked over and collapsed the canopy, anchoring it with several rocks. He had seen Jim and me floating down and had radioed the New Mexico Highway Patrol, the Air Force and the nearest hospital.
Extracting myself from the parachute harness, I discovered the source of those flapping-strap noises heard on the way down. My seat belt and shoulder harness were still draped around me, attached and latched. The lap belt had been shredded on each side of my hips, where the straps had fed through knurled adjustment rollers. The shoulder harness had shredded in a similar manner across my back. The ejection seat had never left the airplane; I had been ripped out of it by the extreme forces, seat belt and shoulder harness still fastened.
I also noted that one of the two lines that supplied oxygen to my pressure suit had come loose, and the other was barely hanging on. If that second line had become detached at high altitude, the deflated pressure suit wouldn't have provided any protection. I knew an oxygen supply was critical for breathing and suit-pressurization, but didn't appreciate how much physical protection an inflated pressure suit could provide. That the suit could withstand forces sufficient to disintegrate an airplane and shred heavy nylon seat belts, yet leave me with only a few bruises and minor whiplash was impressive. I truly appreciated having my own little escape capsule.
After helping me with the chute, Mitchell said he'd check on Jim. He climbed into his helicopter, flew a short distance away and returned about 10 min. later with devastating news: Jim was dead. Apparently, he had suffered a broken neck during the aircraft's disintegration and was killed instantly. Mitchell said his ranch foreman would soon arrive to watch over Jim's body until the authorities arrived.
I asked to see Jim and, after verifying there was nothing more that could be done, agreed to let Mitchell fly me to the Tucumcari hospital, about 60 mi. to the south.
I have vivid memories of that helicopter flight, as well. I didn't know much about rotorcraft, but I knew a lot about "red lines," and Mitchell kept the airspeed at or above red line all the way. The little helicopter vibrated and shook a lot more than I thought it should have. I tried to reassure the cowboy-pilot I was feeling OK; there was no need to rush. But since he'd notified the hospital staff that we were inbound, he insisted we get there as soon as possible. I couldn't help but think how ironic it would be to have survived one disaster only to be done in by the helicopter that had come to my rescue.
However, we made it to the hospital safely--and quickly. Soon, I was able to contact Lockheed's flight test office at Edwards. The test team there had been notified initially about the loss of radio and radar contact, then told the aircraft had been lost. They also knew what our flight conditions had been at the time, and assumed no one could have survived. I briefly explained what had happened, describing in fairly accurate detail the flight conditions prior to breakup.
The next day, our flight profile was duplicated on the SR-71 flight simulator at Beale AFB, Calif. The outcome was identical. Steps were immediately taken to prevent a recurrence of our accident. Testing at a CG aft of normal limits was discontinued, and trim-drag issues were subsequently resolved via aerodynamic means. The inlet control system was continuously improved and, with subsequent development of the Digital Automatic Flight and Inlet Control System, inlet unstarts became rare.
Investigation of our accident revealed that the nose section of the aircraft had broken off aft of the rear cockpit and crashed about 10 mi. from the main wreckage. Parts were scattered over an area approximately 15 mi. long and 10 mi. wide. Extremely high air loads and g-forces, both positive and negative, had literally ripped Jim and me from the airplane. Unbelievably good luck is the only explanation for my escaping relatively unscathed from that disintegrating aircraft
Two weeks after the accident, I was back in an SR-71, flying the first sortie on a brand-new bird at Lockheed's Palmdale, Calif., assembly and test facility. It was my first flight since the accident, so a flight test engineer in the back seat was probably a little apprehensive about my state of mind and confidence. As we roared down the runway and lifted off, I heard an anxious voice over the intercom.
"Bill! Bill! Are you there?"
"Yeah, George. What's the matter?"
"Thank God! I thought you might have left." The rear cockpit of the SR-71 has no forward visibility--only a small window on each side--and George couldn't see me. A big red light on the master-warning panel in the rear cockpit had illuminated just as we rotated, stating, "Pilot Ejected." Fortunately, the cause was a misadjusted microswitch, not my departure.
Bill Weaver flight tested all models of the Mach-2 F-104 Starfighter and the entire family of Mach 3+ Blackbirds--the A-12, YF-12 and SR-71. He subsequently was assigned to Lockheed's L-1011 project as an engineering test pilot, became the company's chief pilot and retired as Division Manager of Commercial Flying Operations. He still flies Orbital Sciences Corp.'s L-1011, which has been modified to carry a Pegasus satellite-launch vehicle (AW&ST Aug. 25, 2003, p. 56). An FAA Designated Engineering Representative Flight Test Pilot, he's also involved in various aircraft-modification projects, conducting certification flight tests

**wonwinglo** · 26-01-2006

The much abused servo in our models needs a bit more tender loving care,treat them well and they will be 'fit and forget' get a few things wrong and you could be in for a nasty surprise,I once saw a large quarter scale model aircraft go into a roll and the servo locked on,after completing another three free-lance rolls she plunged into the ground into a pile of matchwood,the cause was a broken gear tooth which had jammed itself into the works.
Lets start at the way that we mount our servo's,this would appear to be a fairly straight forward task you would be led to think ? however many get it wrong,with your radio set you get a few small packets of hardware,dont loose these as they contain tiny screws and fittings that you will need to re-order if you need more of them,we have four tiny self tapping shouldered screws per servo,that shoulder is vital,this sits upon a metal ferrule that fits into a small rubber stand off grommet,note the 'stand off' bit,this means exactly what it says to raise the servo at just the right height so it floats gently and in doing so absorbs the vibration and knocks etc associated with operating your models,whatever you do,do not just wind down the screws fully and squash them into the bearers,this means instant death to servo's,just nip the screw gently until it is secured,work from one left side corner to the other right side corner,in other words equally tighten up the servo,this is sound engineering practise when handling anything that has multi screws.
Beware of using servo tape,this should only be used as a last resort and if you must use this product then stick at least three layers together,wipe the servo base and model surfaces with a quick wipe of acetone to chemically clean the surfaces,try and support the servo each end with small strips of balsa wood with a piece of servo tape between,this will stop the servo rocking around and destroying itself.
Dont forget to fit the servo arm screw ! it is easily forgotton,also make sure that the linkages are free to move in the servo arms with no stall-out ( see later paragraph on this ) more servos die because they get stalled than anything else,this is the easiest way to burn them out,also dont forget that a lot of the new mini and micro variety have higher gear ratios which adds to the problem,so take care and double check.
Not everyone owns a computer radio to adjust for throttle stall out,so here is how to incorporate a very simple saver for the servo to avoid stripped gears or at the worst a burnt out servo,if your throttle servo is ticking then you need a servo saver installing.
Attach to the servo arm/horn a brass ferrule that is free to rotate,through the ferrule drill a hole the thickness of the servo wire rod,you can buy these fittings made in either brass or nylon but the name escapes me at the moment,now you will need three very small collets or if you are good at soldering two cup washers would do the job but they are difficult to adjust properly,fit one onto the rod about one inch forward of the servo arm,now onto the wire slip a compression spring then another collet which is free to move and butts against the servo arm,next fit the last collet on the end of the servo rod aft of the other side of the arm,this simply stops everything falling off.
To test the device fully open the throttle and note when the spring compresses fully,if the servo stalls out simply adjust the first collet so the spring has closed but at the same time opened the throttle fully without any effort,now close the throttle and once again note how the spring closes,once again adjust accordingly.
If more movement is required such as on older radio sets just fit a longer compression spring.
All that is happening is that the spring is acting as a safety buffer, by not restricting the servo arms movement and thus avoiding the fatal stall out which will at the worst drain your battery and cause you to crash.
There was a commercial device which had a leaf spring attached directly to the servo arm thus causing the arm to give slightly when in the over-ride position.
The white grease as supplied with the servo gearing should last a lifetime of servo use,if you replace gears then do not remove the grease,retrofit brass gears can be useful but a dab of white grease always helps smooth operation,make sure that all gears mesh properly and the lid of the servo is seating properly,the splined servo arm should be pushed well home as well,and dont forget that essential tiny screw that is sometimes missed out !

**wonwinglo** · 27-01-2006

Have you ever wanted to just go and fly without the hassle of sorting out who is on which frequency,or making sure that nobody else is flying,boating or carting nearby,changing crystals etc ? well thanks to the wonders of technology this is all now possible,not only that but the equipment is in place and available,sound too good to be true ? well that is what I thought until I investigated further,this is what I found-
Horizon Hobby distributors turned the whole radio control world upside down and made conventional r/c systems virtually obsolete overnight,this only happened as recently as October 2005 when they announced the new 2.4Ghz Spektrum DX6 DSM radio system,the system says goodbye to interference,conventional crystals or transmitter compounds,and the in-evitable bright spark who insists on switching on his radio in the car park !
The initial radio set introduced the DX6 operates well outside any current operating systems ie 27,35,50,72 mhz thus acceptable in current flying areas,it is totally immune to RF noise so those glitches are a thing of the past.
The DX6 features duel rates,exponential throws on the aileron and elevator sticks,a 10 model memory,3 programmable mixes together with those helicopter specific such as CCPM mixing,pitch and throttle curves,Failsafe is also included,the Spektrum 7 gram AR6000 receiver is included plus 4 S75 servos.
Twenty five models wer flown at once during the JR IndoorElectric Festival in Colombus,OH without a single problem during the event.
So how does it work ? well when you switch on the DX6 automatically searches for,selects and locks onto two clear channels,DX6 frequencies are so much higher than those of conventional RC channels,it will not recognise the existance of any standard channels,consequently other receivers remain completely unaffected by the transmissions from a DX6.
The advantages of this system can be immediately seen in terms of the freedom it gives to other operators,any system that offers such things as glitch free multi-flyer operation and reliability cannot be a bad thing,the 2.4Ghz revolution is upon us now.
Cannot wait to get hold of one.

Nigel.D · 27-01-2006

Thanks for that peice Barry i now can understand greek (or was it nepalese) As im building a tamiya 1/16 King tiger could you please if poss do a bit on servos and recievers etc that numptys like me can understand
cheers mate!!

**wonwinglo** · 27-01-2006

***Its all here for reference Nigel,as you know Scale-models is always on the ball,yes I will do a piece for you on servos and receivers with pleasure.
Actually this new system will be ideal for military enthusiasts,just imagine seventy odd tanks on a miniature battlefield without any frequency problems either !

Quote:

Originally Posted by Nigel.D

Thanks for that peice Barry i now can understand greek (or was it nepalese) As im building a tamiya 1/16 King tiger could you please if poss do a bit on servos and recievers etc that numptys like me can understand
cheers mate!!

Nigel.D · 27-01-2006

now that would be fun!!!!

**Bunkerbarge** · 27-01-2006

Barry,

I was reading about these last time at work and they really do seem the answer to a lot of RC prayers. They would certainly help to prevent lost aircraft, boats cars etc that are the inevitable casualty of inadvertant interference. Suprisingly they are not that expensive either, which is a novelty for new technology.

I may be looking into getting one when I go back next time as it would be even cheaper to obtain one in the States.

**wonwinglo** · 28-01-2006

A unique opportunity to see two Junkers Ju.52 3/m vintage German transport aircraft in the UK next week,and if you are extra lucky to fly in one of these corrugated transports that served with the German Luftwaffe,the two aircraft will arrive from Switzerland where they are operated by a company called JU-AIR,the picture above shows the worlds gathering of five airworthy aircraft assembled in 2005.
Where to see them-
Arriving at Goodwood airfield on Monday 30-01-2006.
Then at Farnborough airfield on 01-02-2006 staying until 02-02-2006.

Seaspray · 28-01-2006

There is no chance that two of these radios operating near each other will lock on to the same frequency ?

Martin

**wonwinglo** · 28-01-2006

*** Not possible Martin,the tolerances are so fine that there is no bleedover like conventional crystal controlled radios which are liable to splatter RF,the system is not as new as we think having been used in full sized aircraft communications for some years without any bother.
The system will only lock onto the respective receiver,also interferance rejection is far superior to conventional systems.

Quote:

Originally Posted by Seaspray

There is no chance that two of these radios operating near each other will lock on to the same frequency ?

Martin