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SteveBeaver
Unregistered
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 Posted Tuesday, February 8, 2011 @ 01:04 PM
Bob,
There is nothing to do here in the snowy, icy, freezing cold American mid-west (so named long before people realized quite how far the continent extended to the left) other than work in the shop, plan next summer's fun, and read, read, read.
I just re-read your excellent June 2007 review of the BD5. You did a nice job of explaining the many facets of the aircraft to be admired, as well as giving a hint at why it's past was so checkered. Made me think that one of the reasons for the relative success of the jet powered variant is the very slow rate of power change the TRS-18 confers. Since it takes almost a fortnight to go from flight idle to climb power, you are less likely to be overwhelmed by the pitch changes I suppose.
Have you had any further thoughts on the aircraft since you flew it? Are those two still at Serpentine? Do you still hanker for one, or was that a passing flirtation?
Steve
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Bob Grimstead
Unregistered
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Posted Wednesday, February 9, 2011 @ 03:10 AM
Hi Steve,
This is very interesting.
I am amazed at how many folk out there are still fascinated (as I was) by this little airplane.
I well remember the initial adverts (I still have them) and following its development over the years in Air Progress and other magazines.
My YouTube page has many, many more hits on the BD-5 footage than on any other.
But, I suspect many of them are not pilots or engineers, but wanna-bes, and far too many people (pilots and W Mittys) are convinced it's the perfect airplane and WILL NOT hear a word of criticism about it.
This is a bit like religious fanaticism, and many of these fanatics and fantacists have posted vast amounts of info on the web -- much of it misguided or downright wrong.
Yes, my enthusiasm was a passing flirtation, although I really meant it at the time.
I truly was surprised at what a thoroughly nice airplane it was to fly.
Although I should not have been surprised, already knowing, as I did, what a great designer is Jim Bede, and that some guy called Rutan was that particular aerodynamic sorcerer's apprentice.
I was going to say it was 'viceless' because it very nearly is.
Trouble it, its only two real vices are killers (and have often been so) in one particular set of circumstances.
When the engine stops producing power, and particularly if it does so suddenly, its nose pitches up.
If the pilot is good, experienced, and very quick, I'm told he can arrest that pitch-up before it stalls.
However, once the nose has pitched up, without propwash aiding the tail, you cannot pitch it down again, so you can STOP it, but not CORRECT it.
The other disadvantage is the lack of absorbent structure below and ahead of the pilot in an impact.
This does not matter so much in a glider, which has a similar nose, because its landing/stall/touchdown speed/energy is relatively low.
Here follows a letter I wote to another BD-5 devotee a few weeks after one of our Serpentine Bedes crashed, breaking the pilot's back and burning him (and this was an expereinced pilot, a most expereinced Bede pilot, and builder of two BD-5s)...
I have to say that, in the light of recent events, I've been reviewing the BD-5's secondary safety.
I am happy that (with the sole exception of that pitch-up after engine failure) its flying characteristics are fine.
The real problems are the unreliability of an automotive powerplant buried in the rear fuselage (and therefore prone to overheating) and the airframe's lack of crashworthiness. I had a chat with the PFA's Ken Cragie about it yesterday.
Having no absorbent structure ahead and around you in a glider stalling clean at 30 knots is rather different from a Bede stalling clean at 70. My calculator says the latter has 5.444 times the energy of the former, and your body will have to absorb all that.
Peter's broken back means he'll never walk again, and he'll certainly never again fly his Bede, although in the fullness of time he might be able to modify a Cherokee or something.
I think that's a risk I'm no longer prepared to take, so I'll stick with my slow, low wing-loading aeroplanes, thanks.
Good luck with your Bede flying. Yours, Bob
I saw Peter yesterday. He's driving an automatic Saab and still cheery, but his Bede was destroyed and of course his life won't be the same again.
One answer to the Bede conundrum is Gordon's very lightweight but reliable engine -- and more importantly, its installation.
I would not have considered a Bede unless I was on the same airfield as Gordon and could share in his expertise.
The Honda Civic engines, as used in Peter's crashed example are really too heavy, they put the C of G too far aft and exacerbate its instability, particularly after engine failure.
But you watch now.
You think you have to keep your head below the sand-bags when I recommended PolyFiber, just you watch the flak I get for having dared to criticize just one aspect of what is otherwise a fine airplane!
Yours, Bob
[Edit by Bob Grimstead on Wednesday, February 9, 2011 @ 03:51 AM]
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Bob Grimstead
Unregistered
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Posted Wednesday, February 9, 2011 @ 03:17 AM
Here is part of the research I did before flying Gordon's BD-5 and writing that article.
I try to be professional in everything I do, and I knew there would probably be quite a lot of interest in this type -- although at that time I had no idea quite how much interest there would be, so I thought it prudent to prepare a little more than I usually do.
Yours, Bob
On the NTSB Database, I found 61 BD-5 accidents (of which 7 were jet versions and 5 were turboprops) over thirty years and perhaps 600 flying examples. 24 were fatal (of which 5 were in turbine versions). Five were the usual canopy, undercarriage and flap problems. 35 related to engine, drive or propeller malfunction. Seventeen were stall, spin or failed to maintain flying speed accidents, but tellingly, there were none of these in past 14 years since the new aerofoils were introduced. No fewer than 26 of these 61 pilots had just three hours or less on type, and for fourteen of them (one quarter) it was their first Bede flight.
There were, of course, plenty of Bede accidents in other countries as well as the USA, but it seemed likely that there had been so many in the USA that I could reasonably derive some trends.
Here are a few of the more relevant accidents...
N84EJ After lift off from the runway, at about six to eight feet, the landing gear was retracted & the nose of the airplane pitched down. The airplane is equipped with a side stick controller & a manually actuated landing gear. The landing gear handle is located forward of the pilot in the center of the floor, between the pilot's legs, and is pulled aft to retract the gear. The bottom of the airplane contacted the runway which separated the oil cooler scoop. The pilot then entered a right hand traffic pattern. According to witnesses, as the airplane was turned from the base to final leg it stalled abruptly, rolled left more than once, and began a vertical dive to impact. Post crash examination of the airplane revealed fire damage and continuity of the flight controls. The pilot's handbook indicates that an accelerated stall will result in a left roll. it also states that stall buffet will occur about 72 mph. The log book noted that the airplane had a clean stall speed of 80 mph, & a stall speed of 85 mph in a 60 degree one 'g' right turn.
N3DW The airplane's engine had a total loss of power during takeoff climb. Witnesses reported 'seeing the aircraft fall straight down to the ground.' FAA airworthiness inspectors examined the airplane's engine and could find no pre-existing deficiencies which would account for the loss of engine power. Examination of the pilot's logbook entries showed no entries for a biennial flight review, and he last logged a flight on march 26, 1990. Friends of the pilot reported that he had periodically flown the accident airplane since he purchased it in march 1992. A witness also reported that the pilot had not attempted power off stalls in the accident airplane. A diligent search was conducted by the FAA to determine if the pilot had a current medical certificate, but concluded that a current medical certificate was not on file. 1) a total loss of engine power for undetermined reasons, 2) the pilot's failure to maintain an adequate airspeed, and 3) the inadvertent entry into a stall spin. Factors in this accident were: 1) the pilot's lack of familiarity with the airplane, and 2) the pilot's lack of recent aeronautical experience.
N29DT During the first test flight of an experimental aircraft, the aircraft was observed in a right descending roll which eventually collided with the terrain. Due to extensive impact damage, several of the aircraft’s components were too badly damaged to determine if there were any mechanical failures or malfunctions with the aircraft prior to the accident. Of the components that were examined, there were no reported mechanical failures or malfunctions. aircraft control not maintained. lack of total experience in type of aircraft..pilot in command
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Bob Grimstead
Unregistered
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Posted Wednesday, February 9, 2011 @ 03:20 AM
N548BD The owner/builder had hired the plt to test fly the acft on its initial flt. Shortly after takeoff, the pilot transmitted that he had an engine problem. He was cleared for an immediate landing & entered a downwind for rwy 28. As he continued and was turning from a base to final approach, the aircraft entered a spin in the opposite direction. It impacted on the edge of an interstate highway while in a steep nose-down attitude. Exam of the eng revealed the #1 cyclinder spark plug wire was completely detached; the #2 cylinder wire was detached from the spark plug (altho its dust boot was still connected); & the #4 spark plug wire dust boot showed evidence of having come in contact with an adjacent exhaust stack & was burned until there was separation at the boot's midpoint. aircraft handling..not maintained..pilot in command. ignition system,high tension wiring..disconnected. stall/spin..inadvertent..pilot in command. maintenance,installation..improper..other maintenance personnel
N23105 The acft rolled inverted & collided with the ground after an overtemperature reading, an rpm loss and loss of airspeed were recognized by the pilot during the recording of the takeoff. The pilot had a portable recorder on board and was using it during the takeoff. He said the 195 degree temperature was 'no big deal' but then noted a drop in airspeed and stopped talking. The recorder kept operating until the crash and recorded an rpm reduction to nearly idle. Post accident exam noted scoring & blueing of #1 & 2 cylinder walls indicating overheating & possible seizure of the eng. Fuel was found in the eng & fuel lines. airspeed..not maintained..pilot in command. engine assembly..overtemperature. stall..uncontrolled..pilot in command
N5KB Prior to the accident, witnesses aprx 9 mi sw of the crash site saw an acft (matching the description of N5KB) flying at about 100 to 200 ft over the water on a north-easterly heading. It then pulled up in a steep climbing turn toward the shoreline. No known witnesses saw the acdnt; however, several persons clearly heard the eng sputtering or cutting in & out just prior the the crash. Exam of the crash site revealed the acft had impacted in trees while in a steep descent. No preimpact part failure or malfunction was found that would have caused a loss of control. The acft was equipped with a 3 cylinder, 2 cycle, reciprocating eng which had 3 carburetors. Water & foreign material were found in the bowls of all 3 carburetors, and the fuel filter was found to be contaminated with water & foreign material. During an eng teardown, evidence of overheating & scouring of the #3 piston & cylinder was also noted.
N500BR while turning from downwind to base a loss of pwr was experienced after which the acft stalled and impacted a corn fld. The wreckage revealed no evidence of fuel in the left tank and only about an ounce of fuel in the carburetor. Fuel burn on the terrain under the right wing indicated fuel was available in the right tank. The fuel selector was positioned on the left tank. Further examination revealed a sealant used on the wing fuel tanks had coated the glass sight fuel gages thus restricting the plts ability to adequately determine fuel quantity inflight. airspeed..not maintained..pilot in command fuel tank selector position..improper.
N83SK The acft crashed short of the rwy during an attempted landing. There were some confusing and garbled transmissions and some mistaken instructions from the tower during the problem experienced by the accident plt. This pilot did not make it clear that he had an emergency but he did ask for immediate landing due to a problem. His engine was heard operating at alternating high and low levels. This acft had a history of overheating and it also had an improper propeller installed. A new propeller was on order. According to Great American Propeller co, the propeller installed on the acft did not have enough blade area for the airframe/engine combination. This combination could cause enforced moderate application of throttle and at full throttle and low airspeeds could result in excessive rpm and probable cavitation and loss of thrust.
N381JH After takeoff the amateur built Bede-5 entered left traffic and circled the airport once at 700 to 1000 feet agl. During the second 180 degree turn from the downwind leg to the runway heading a witness reported that the bank angle suddenly increased and the nose of the aircraft dropped resulting in a nearly vertical descent to the ground. The aircraft came to rest approximately 1/4 mile short of runway 07. Examination of the flight controls and attachments revealed no signs of preimpact discrepancies or malfunctions.
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Bob Grimstead
Unregistered
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Posted Wednesday, February 9, 2011 @ 03:22 AM
N8TW stall: mush in flight: low pass probable cause(s) pilot in command failed to follow
approved procedures. airframe - landing gear – jammed. pilot in command failed to maintain flying speed remarks- gear handle not fully up, moved down during 2g pull-up, gear jammed in intermediate position. behind power curve/mushed,lo apch
N25BD Engine failure or malfunction landing: final approach. controlled collision with ground. landing: level off/touchdown. probable cause(s)
pilot in command - improper in-flight decisions or planning, mismanagement of fuel,
inattentive to fuel supply, fuel starvation, complete power loss, forced landing on airport.
plt stated failed to switch to fullest fuel tank.
N8065V phase of operation in flight: normal cruise, propeller failure, forced landing off airport. controlled collision with ground on touchdown
probable cause poor/inadequate design of reduction gear assembly & propeller shaft material failure. scotch weld & aluminum pop rivets on prop drive assy failed. scotch weld not suitable for hi temp.
N52BM complete power loss: engine lost power during an attempt to lower the gear. Honda EB-2 engine. wheels-up forced landing on airport. probable cause(s) improper operation of powerplant & powerplant controls.
N78MJ partial power loss on takeoff: initial climb, forced landing off airport.
drive belt,p/n 1-0812,connecting eng crankshaft pulley to prop shaft slipping.
N177RB excessive wear, flap handle pin, mating holes. Flaps retracted, aircraft landed short. hard landing. gear collapsed 70 hrs tt.
N87921 drive coupling ceased transmitting power to propeller on initial climb. controlled landing, collision with ground on touchdown remarks- first flight.
N503BD Initial climb, powerplant failure for undetermined reasons, stall.
pilot in command - failed to maintain flying speed, lack of familiarity with aircraft
remarks- acft obsvd in steep left bank prior to descent.
N733ST stall: mush initial climb, undetermined. pilot stated eng apprd to be running normally, but acft mushed into grnd from 100 ft alt. first flight.
N99775 stall: spin in flight: unrecoverable mode by high angle of attack with gaw-2 wing. spin test characteristics of gaw-1 airfoil.
N13SL initial climb pilot lost pitch control through improper operation of flight controls.
factor(s) pilot in command - lack of familiarity with aircraft. inadequate flight training-procedures. initial flt in single seat acft. .no prev jet flt exp. plt flew in simulator.
N501PB initial climb complete engine failure due fuel starvation. stall. pilot failed to maintain flying speed. small diameter fuel lines used with one of two fuel pumps removed.
N61TC engine failure or malfunction in climb. powerplant - lubricating system: B nut fitting improperly installed/secured in oil system. Honda Civic eng. oil exhaustion. landing: roll, gear collapsed. lack of familiarity with aircraft. complete engine failure, forced landing off airport on land in nursery.
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Bob Grimstead
Unregistered
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Posted Wednesday, February 9, 2011 @ 03:36 AM
I have lots more info on the BD-5, but I guess that lot is the most supportive of my decision not to buy one after all.
Gee, after all that work, I should have been an aviation consultant, shouldn't I?
Sorry if I've disappointed you Steve.
I'll say it again, it's basically a fine airplane, but it needs a light and reliable engine.
And yes, jets are both light and reliable.
I well remember the wonderful air test of his BD-5J by my great hero and idol, Richard Bach.
And I must have at least half-a-dozen other Bede air tests, all of which I read most thoroughly before attempting to fly Gordon's.
One famous journalist (the guy who built Melmoth? Peter Garrison?) experienced (yes, I can spell it, but my fingers fly over the keys faster than I can control them!) an engine failure during his air test flight, and coped very well (lightweight Hirth engine, I think, so forward C of G).
I read that one many times, as you can imagine.
I still remain ambivalent.
People want so much money for them, but if I was given one, no question, I'd use an engine like Gordon's and get it flying.
Then I'd always have a strong elastic band around the sidestick and hooked on to something ahead of it for all take-offs, so that I had to overpower the resulting pitch-down for a normal take-off, but if I relaxed (as, when distracted by an engine failure) it would immediately pitch safely forwards.
PS, the published version of my article, although unusually long, was about half the length of the original, since I'd done so much research, and like the over-keen exam candidate, I pretty much wrote all I knew on the subject.
Stay warm.
Yours, Bob
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SteveBeaver
Unregistered
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Posted Wednesday, February 9, 2011 @ 09:30 AM
Wow. Thank you bob. It was kind of you to take the time to post all of this fascinating stuff. Those pictures are certainly food for thought.
The autogyro community seems to have come to the conclusion that the thrust line of a pusher gyro needs to be aligned with the CG as well. Their accident rate has much improved as this dictum has gained acceptance.
Jim Bede is still around, and despite the BD5 and the BD10 debacles, he turns up at airshows here in the American mid-west with a van and a white tent, pushing his BD17 - something of an ugly duckling compared to his previous designs, and built of aluminium honeycomb.
Claimed build time is 40 hours!
Peter Garrison went on to design, build, and fly Melmoth II. A quite incredible feat that you can read about on his excellent website/blog.
www.melmoth2.com - The "Progress" page is particularly interesting.
Thanks again for the insight into the BD5. It really is interesting stuff. A plane that looks that good should fly better!
Steve
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Bob Grimstead
Unregistered
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Posted Thursday, February 10, 2011 @ 09:46 PM
Incidentally, in further regard to Peter's accident, he usually retracted his landing gear only after passing the upwind end of the runway.
That day, because they were taking off in formation past a crowd, he retracted his wheels immediately after becoming airborne, and then retracted his flaps.
Then, at about 100 feet, his engine failed.
He managed to extend his flaps in time, but not his wheels.
In a BD-5, as in an RF4, the only impact-absorbing structure below the pilot is the landing gear; also in a BD-5 the first thing to hit the ground if the wheels are retracted is the main spar, which is also the fuel tank.
If Peter had his wheels down, he may not have broken his back, and there would probably have been no fire.
This is all further support for the advice in
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=yEhtrcpRhDqjRTaCt19oXZNtNR&forum=12&thread=509
Yours, Bob
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