Product
1/6th Scale Rear Bear Maiden Flight Crash
Question:
Dear Sirs: I have included some photos of my Rare Bear model after it crashed on it¡¯s maiden flight due to complete horizontal stabilizer failure. The aircraft was at approximately 150 feet of altitude, at ½ throttle on an Enya 80 XF Ring, flying straight and level with landing gear in the down position, beginning the third circuit around our field when first the port, and then starboard horizontal stabilizers failed. The aircraft was assembled and balanced as per your instruction manual using kit supplied hardware for all control surface hinging and connections to the servos. As the photos demonstrate, the stabilizer carbon fiber tubes and root ribs are still glued to the fuselage, along with some parts of the secondary stabilizer ribs. I am 51 years old and have been building and flying Radio Control models since 1968, my deduction as to what happened, along with my fellow club members who witnessed the accident is as follows: The horizontal stabilizers show no longerons connecting the rib structure beneath the sheeting, all loads were concentrated on the initial ribs close to the root and possibly the balsa sheeting was not strong enough to handle the stress. Since the aircraft was flying straight and level and at half throttle with landing gear extended, there were no undue stress placed on the stabilizer due to excess G¡¯s or speed. If there was flutter, it may have been caused by excessive flexing of the factory supplied links and/or pushrod, or maybe there was inferior workmanship in the manufacturing of the stabilizer, notice the rear spar is cracked down it¡¯s center line, where the hinge cuts were made at the factory. The aircraft was not completely destroyed because I immediately cut the throttle to idle and though the aircraft plunged straight down, it crashed in a recently plowed farm and therefore the soil was very loose and deep, though the nylon spinner did break in two. At this time I do not believe there was any engine damage but I have yet to clean and disassemble it, the R/C equipment and retracts seem to have survived. I purchased this aircraft from Chief Aircraft at the beginning of 2005 and just got around to finishing it recently, I travel quite a bit in my job, I believe it to be one of the first runs of the kit and if there was a design flaw or problem with quality control, I hope it has been fixed - today I learned of another Rare Bear purchased around the same time as mine that suffered the same fate as mine. I believe that Thunder Tiger shares most if not all the responsibility for this accident and will, if necessary, supply signed statements of those club members who witnessed this flight, four of which stated they were going to purchase the Rare Bear prior to the flight, verifying what I have stated. I have lost the time and money I invested in assembling this aircraft, and though I will never recover the time, I believe I deserve a new 1/6th Scale Rare Bear kit from Thunder Tiger is due to me. If the stabilizer design has not changed, I will remove the plastic film and cover the entire stabilizer with fiberglass cloth to strengthen it, I will also use a carbon fiber pushrod for the elevators instead of the balsa/plywood one supplied in the kit. I would appreciate your response in a timely fashion, Yours truly, Jeffrey M. Berry
Answer:
Dear Jeff, Thank you for the mail. It was a known issue in the first batch of Rare Bear that the horizontal stabilizers were not strong enough to handle the stress as you stated . However, we have supplied improved tails with three layers of ribs instead of the original ones with only one layer of rib for each of the released Rare Bear soon after that. We are so surprised at this that happened again. Please feel free to contact our subsidiary company ACE HOBBY in USA as follows for service. ACE HOBBY DISTRIBUTORS, INC. Tel: 949-833-0088, 949-833-7498 Fax: 949-833-0003 E-mail: sales@acehobby.com Web: www.acehobby.com Contact person: Anthony Herbert, anthony@acehobby.com, Ext. 250 Best regards, Customer Service Thunder Tiger Corp. [ Simon ]
Dear Sirs: I have included some photos of my Rare Bear model after it crashed on it¡¯s maiden flight due to complete horizontal stabilizer failure. The aircraft was at approximately 150 feet of altitude, at ½ throttle on an Enya 80 XF Ring, flying straight and level with landing gear in the down position, beginning the third circuit around our field when first the port, and then starboard horizontal stabilizers failed. The aircraft was assembled and balanced as per your instruction manual using kit supplied hardware for all control surface hinging and connections to the servos. As the photos demonstrate, the stabilizer carbon fiber tubes and root ribs are still glued to the fuselage, along with some parts of the secondary stabilizer ribs. I am 51 years old and have been building and flying Radio Control models since 1968, my deduction as to what happened, along with my fellow club members who witnessed the accident is as follows: The horizontal stabilizers show no longerons connecting the rib structure beneath the sheeting, all loads were concentrated on the initial ribs close to the root and possibly the balsa sheeting was not strong enough to handle the stress. Since the aircraft was flying straight and level and at half throttle with landing gear extended, there were no undue stress placed on the stabilizer due to excess G¡¯s or speed. If there was flutter, it may have been caused by excessive flexing of the factory supplied links and/or pushrod, or maybe there was inferior workmanship in the manufacturing of the stabilizer, notice the rear spar is cracked down it¡¯s center line, where the hinge cuts were made at the factory. The aircraft was not completely destroyed because I immediately cut the throttle to idle and though the aircraft plunged straight down, it crashed in a recently plowed farm and therefore the soil was very loose and deep, though the nylon spinner did break in two. At this time I do not believe there was any engine damage but I have yet to clean and disassemble it, the R/C equipment and retracts seem to have survived. I purchased this aircraft from Chief Aircraft at the beginning of 2005 and just got around to finishing it recently, I travel quite a bit in my job, I believe it to be one of the first runs of the kit and if there was a design flaw or problem with quality control, I hope it has been fixed - today I learned of another Rare Bear purchased around the same time as mine that suffered the same fate as mine. I believe that Thunder Tiger shares most if not all the responsibility for this accident and will, if necessary, supply signed statements of those club members who witnessed this flight, four of which stated they were going to purchase the Rare Bear prior to the flight, verifying what I have stated. I have lost the time and money I invested in assembling this aircraft, and though I will never recover the time, I believe I deserve a new 1/6th Scale Rare Bear kit from Thunder Tiger is due to me. If the stabilizer design has not changed, I will remove the plastic film and cover the entire stabilizer with fiberglass cloth to strengthen it, I will also use a carbon fiber pushrod for the elevators instead of the balsa/plywood one supplied in the kit. I would appreciate your response in a timely fashion, Yours truly, Jeffrey M. Berry
Answer:
Dear Jeff, Thank you for the mail. It was a known issue in the first batch of Rare Bear that the horizontal stabilizers were not strong enough to handle the stress as you stated . However, we have supplied improved tails with three layers of ribs instead of the original ones with only one layer of rib for each of the released Rare Bear soon after that. We are so surprised at this that happened again. Please feel free to contact our subsidiary company ACE HOBBY in USA as follows for service. ACE HOBBY DISTRIBUTORS, INC. Tel: 949-833-0088, 949-833-7498 Fax: 949-833-0003 E-mail: sales@acehobby.com Web: www.acehobby.com Contact person: Anthony Herbert, anthony@acehobby.com, Ext. 250 Best regards, Customer Service Thunder Tiger Corp. [ Simon ]
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