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RE: Red Arrow Hawk
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ORIGINAL: JoelP I was assisting Tom with the maiden flight and witnessed the whole thing. Not a lot "bang for the buck" at approx 2500$ for only 90 seconds! From what I saw, both wing panels, were fluttering and flapping, much the same way the full scale F-16 did early in it's testing. Tom wasn't even at half throttle in straight and level flight when this occurred. Plane was not going more than 100 MPH best guess. A well designed and manufactured ARF should not end with catastrophic flight as this one did. I had a chance to see inside the wings after the damage was accessed and I'm not impressed at all. Skymaster advertises that they use Hysol in their ARFS...this is true in regards to the fuselage construction. All I saw in the wings was a "hot melt" type of glue that had no reasonable adhesive quality; no Hysol in the wings. You could easily pull the skins from what ribs were in the wing with little to no effort. Tom could have had 8611's in these wings and they would have failed based on what I saw. Did he get a Friday afternoon special? No one will ever know for sure but one thing is sure: Tom is a good builder. I had the chance to look it over before the maiden and he had it tight; very clean install too! The 3421's survived the ordeal! The plane looked great for an ARF. I was impressed with the size and finish of the model. And I was ready to purchase one awaiting the outcome of the maiden and the following dayview at the Austin jet meet. I'm very sorry that this happened to Tom, but at least I won't make the same mistake. Skymaster is off my purchase list after seeing the wing construction but more importantly, for the complete lack of customer service/care afforded to Tom, from the dealer to the factory, after this deal. You guys can take this for what it's worth. My post here is simply to inform and warn others that this jet needs additional engineering to be absolutely airworthy. My only regret is that we did not have a video camera with us that day! While I dont want to get into a debate over the loss of Tom's Hawk, it's always a tough swallow to loose a plane... Especially on a maiden. I do think it is important to clarify some of the facts that where presented in this case. From the discussion Tom had separately with myself and Eric, it seemed fairly clear that Toms flutter was induced by the aileron servos breaking free from their mounts. There was no indication of wing failure or a manufacturing issue and Toms own admission indicating failed servo mounts. I do have to admit, I question the integrity of Skymasters suggested servo mounting and do not use the supplied hardware for my builds. I have been cautious of this method for several years, my first exposure to a similar system, the BVM mounts. Personally, there just does not seem to be enough surface area to make a solid structural bond using the mount blocks alone and if I did use this method, I ALWAYS created a floor plate, drilled anchor holes in the blocks for the glue and added heavy triangle stock to increase the glue surface area. Tom indicated that he had just glued the blocks to the wing skin. My preferred method is the Rob Jainger (now TAMS) servo mounts. These mounts provide a bonding area that is slightly larger than the servo area itself (see pic below). As for the comments regarding the wing construction..... Skymaster uses a epoxy/silica mix for wing assemblies. Weight is always an issue in theses aircraft, building an entire wing out of Hysol would produce an excessively heavy panel....not to mention way overkill for this type of structure. Skymaster uses Hysol in strategic areas where the added strength of this glue is needed... Fuselage formers, engine mounts, gear mounts and the like. I would not build a wing with hysol (except in high bearing areas) why would I expect skymaster too? Tom was presented with a more-than-generous offer from Airpac/Skymaster on a replacement kit... I am sorry for his loss and disappointed he has decided not to build another. Todd |
RE: Red Arrow Hawk
David
I suspect it's an awkward area to photograph , but could you post some shots of your modifications if they won't be in the upcoming RCJI article.I will be flying off grass and would appreciate the assistance. Could you also confirm what struts you are using. John |
RE: Red Arrow Hawk
John,
It is difficult to photograph now that everything is back together but the mods are in next RCJI about to hit the streets. In addition I have now added a carbon plate under the front landing gear bearer to strengthen and stiffen it. The article also suggests that the Skymaster wing servo mounting system is totally inadequate and suggestions on how to inprove it which includes a ply load spreader and attchment of the mounting blocks to the surrounding structure to stabilize them. The supplied plywood blocks used for servo mounting were consigned to the rubbish bin, they were pieces of poor quality plywood, totally inadequate, replaced by beech blocks. Struts are standard Skymaster. I both agree and disagree with Todd ! Whilst there is no point in using Hysol throughout the wing, in highly stressed aras around the landing gear Hysol WOULD be advisable , the weight increase would be negligible. Unfortunately on my Hawk in some areas around the landing gear mount structure there were considerable gaps with nothing attaching the skin to the ribs. Hysol (from Dreamworks !) soon fixed that ! But I think there is one overriding issue. Models such as the Hawk will appeal to many newcomers to gas turbine flying, and they might not have our experience to detect the sort of problem which killed Tom's Hawk. For that reason, if no other, Skymaster and other companies producing high performance ARTF jets MUST ensure that all the structure and components are totally airworthy without needing any modification or change. If that policy is not persued we may see lots more accidents such as Toms; Hawk loss with possibly disatrous results to us all. Certainly all the mods. I have suggested for the Hawk could be incorporated at the factory at minimal cost in time and money and will improve the airworthiness and serviceability of what is otherwise a really excellent model. Hope this is not seen as preaching, but it is how I feel. Regards, David Gladwin. |
RE: Red Arrow Hawk
Tom,We are sorry for your loss. Also, we appreciate everyones comments regarding this issue. Skymaster/ Airpac will always consider any suggestions or comments to improve our planes.
We try to provide the best customer service we can. When this accident happened, we did spent a quite of bit of time discussing it with Tom. We spent a lot of time discussing it internally as well. I even provided Tom with my cellular number so that he could even reach me on Sunday. From Tom's description we are unable to find any structural defects from production that could have caused this accident. We agree that Skymaster still has room for improvement such as with the instruction manual or servo mount material. We are making efforts to change those good suggestions immediately. As a manufacturer, we will be responsible for any defective products. After nearly 1000 Skymaster planes sold, many customers respect the type of service for any replacement products for defective items we provide. We don't try to avoid any quality issues, which we feel that we are responsible for such as high quality products and flight safety. However, we cannot just give away our products to everyone who has damaged their plane. We need to first determine if it was defects due to production or design error, or if it was due to other causes. In Tom's case, we don't feel that any production or design defects was the problem. We did feel bad for Tom's loss and offered him a good discount on another plane. However, we can't afford to replace the entire kit for those issues that are not direct related to Skymaster's defects. As Todd explained and clarified some misconceptions, I don't think I have to really repeat this here. For those that are concerned about adhesion issues, you shouldn't have to worry about that. If you guys don't know by now, adhesives is my main business (Handibond Adhesive). We don't find it necessary to save on glue, when we are the manufacturer (expect Hysol). Also, we do have the technical knowledge on what applications are necessary. In Tom's case, Tom did agree that the wing had "no issue with glue on the flat. He agreed it was a strong wing. The problem is the Aileron flutter that caused the damage. We agree that some of the issues that David mentioned did happened in the earlier production of our Hawks. This hasn't been the case since we've moved to our new facilities. The problem he mentioned has to do with the landing gear, which is totally unrelated to how Tom's plane crashed. Of course we value Davids opinion. The issues don't exist in our current production. However, we will take extra care so those problems will not arise. (Dave, if you have a chance to see our current production or check out our facilities, you will have a totally different perspective than the plane you have now). Tom, again, we are sorry for you loss. If you have a chance to see more Skymaster planes fly, you will see that it is very rewarding. I just hope you haven't lossed that much confidence in us. If you want to try another one out, just remember my offer always stands. |
RE: Red Arrow Hawk
ORIGINAL: BirdofpraY David, I too find the finish work on the fuse and wing outstanding, I thought I have to say the retracts and struts are fine the way they are, also I find no need to add carbon fiber plates to the gear mounts as they are sound the way they are. At Florida Jets I landed her three times at 90mhr and never once did I tear up the gear or the gear blocks. But I do suggest not using the Skymaster brakes as the do not perform very well. My Hawk flys very scale on a P70. plenty on performance for me. All in all this a great quality jet ARF for the money. I plan on getting the all white one and doing it up in a diffrent scheam like ones in the pics I post here. Thanks |
RE: Red Arrow Hawk
David
Ok. I will wait until RCJI hits the bookshelves! From Eric Wu's response it would appear that most of the issues will be resolved, of course that does not help the number of jet flyers who have bought an eary version of the kit! I am just about to place my order with Ali and hope I get a modified kit! Mine will be powered by my new Wren Supersport and, in the interests of lightness I shall use a Wren tailpipe and my own tanks ( 1500 cc + hopper will give 6 minutes + on the Supersport) I too would be interested in hearing how the P70 flies the Hawk as the performance should be broadly similiar. BTW my Wren was putting out 19lbs of thrust under test and there is a weight saving of almost 2lbs over the P70 (my SS is manual start with on-board starter) John |
RE: Red Arrow Hawk
I think that reply is one of the most mature and business -like responses I have seen from a kit manufacturer and I am delighted that my observations have been taken in the way they were intended, i. e. constructive criticism intended to make a good model better. I wish Skymaster and Airpac every success.
I think the Wren will be fine off tarmac but not off grass unless its very smooth. Mine is flying with a derated 160 which looks just about right ! The white strobe on mine makes it look even better ! I hear criticism of the brakes. Whilst they will not lock up the wheels they are more powerful than one might imagine and do provide very smooth retardation. My Hawk has shown exemplary flying with no sign of tip stalling. C of G is as per manual with a full hopper and a few ounces of fuel in the, horizontal, smaller tank which means its dry c of g is actually a little aft of the manual position. Smooth as silk and feels absolutely "solid" with very axial rolls. Regards, David Gladwin. |
RE: Red Arrow Hawk
David
I am sure the Wren will be ok as we have a 90m x 6m tarmac strip which we tend to use for takeoff only and we land on the grass to slow the models down more quickly. John |
RE: Red Arrow Hawk
Eric,
I read your post about Tom's loss with great interest. I was at the field when Tom's plane went in and I concur wholly with Joel's remarks about speed, etc. Both wings were fluttering severely prior to the crash even though Tom had slowed the plane considerably. At this point, however, I strongly disagree with your conclusion that, because over 1000 have been sold, it must be a good product. Why didn't you put out a "Manufacturer's Alert", much like what Tam did when there were structural issues with the Viper Jet? Servos shouldn't be pulled out of the wing if installed in accordance with the manufacturers recommendation. It was my intention to buy a Hawk also; no longer. I believe you and the manufacturer have been remiss in informing the Jet community on a timely basis of the more serious defects in this airplane. Tom should not have suffered this kind of financial loss when he merely followed instructions. Thats my 2 cents worth! Regards, Rob Puetz |
RE: Red Arrow Hawk
Surely if there was an out and out manufacturing defect witht he aileron mounts or the wing strength on the hawk all of them would have crashed in the same fashion? I am also on my third Hawk (First two sold and flown many times) I used the normal skymaster servo mounts (Wooden blocks) The only thing I did differently was I made sure I roughened the area that the blocks glue to really well. I also soaked the wooden blocks in this cyno to increase the bond between the ply.
My last Hawk flew with a AMt mercury 20 lbs of thrust, and ready to fly this model was a good few pounds heavier than my first and third version. Yet it still flew from some really rough grass strips with fair ease. I think the Wren combo will be amazing due to the overall low airframe weight. The only concern I would have is that I think this combo would benefit from the use of one of Wrens purpose made tail pipes. Nice and light and probably more efficient for the Super Sport. Just my 2 pence worth |
RE: Red Arrow Hawk
3Demon
I do intend to use the Wren pipe (see earlier post) however Wren have PM'd me to advise that the standard 54 pipe will need to to be strengthened to cope with the SS power. I will post details when I have discussed this with Wren. I don't have my Hawk kit yet but I will need a modified pipe for my Super Bandit which will be the first airframe for the SS. John |
RE: Red Arrow Hawk
Todd,
I respectfully disagree with your statement that the aileron mounts broke free and that is what caused the flutter. What would cause them to break loose with out the stress of flutter? The airplane was in level flight at low speed. The ailerons fluttered so violently the control rods bent, the Robart hinge points broke and the servo mounts broke free. I dont see how this much damage could have occurred if the servo has been inadequately glued and just broke free to start the event. |
RE: Red Arrow Hawk
Hi Tom,
I have had the misfortune of flying two aircraft that experienced severe flutter, one which the control arm stripped on a servo due to the builder failed to tighten the retaining screw (a eurosport) and the other a pull-pull cable disconnected. I was fortunate enough to bring the Euro back with minor damage but the entire vertical fin was fluttering a good 5 inches in each direction, it's saving grace was the flexibility of the fuse in this section after the supporting former snapped like a twig. Had it not been capable of flexing easily, I have no doubt the fin would have left the airframe. The second aircraft disintegrated almost immediately after the cable failed.... Both where flying at low speed (below 100mph) at the time of failure. Flutter of a control surface, even at the lower end of the speed spectrum is typically a very destructive event. When the flutter is induced by a free flowing surface (not just play in the linkage), the frequency is usually explosive. The description you provided of the incident, control rods bent but servo gear train intact in addition to both servos broken free from their mounts would provide a clear conclusion (to me) that your flutter was induced by failure at the mounts. As Eric said, our offer stands should you should you decide to build another Skymaster product. In addition to the offer on a discounted kit, I will extend that offer even further.... If you wish to purchase another kit, I will provide you all of the TAM servo mounts needed and a SM ball bearing linkage kit free of charge. I am truly sorry for the loss, I have lost on maidens myself and know how discouraging it can be. Regards, Todd |
RE: Red Arrow Hawk
Todd,
While I have no hard feelings toward you personally, I will not under, any circumstances, buy another Skymaster product. Neither will I recommend them to anyone else. I guess at times goes on one of us will be proven wrong about our ideas of this kit. If I'm right there will be more crashes if you are correct everyone will be happy with their models. As for me I will not buy a kit another Hawk that requires modification to make it airworthy. Maybe one day we can sit in the pits, have a cold beer and talk about our airplanes but I wont be flying Skymaster products. |
RE: Red Arrow Hawk
Maybe one day we can sit in the pits, have a cold beer and talk about our airplanes |
RE: Red Arrow Hawk
I'll take you up on your offer!
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RE: Red Arrow Hawk
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Well guys as far as I'm concern I think that the hawk is a great flying air plane after seeing one fly at Florida Jets I was pretty impress with the way it slowed down. Unfortunately the one that I received I was not to happy with it as I will make sure to re glue everything on this airplane. My Hawk has very poor glue joints and it seems like they did not sand the fuse before they glued the formers in place with aeropoxy. I do have to say that plenty of my friends have Skymaster planes and I have not seen one break apart in the air. I guess I was just one of the unlucky ones.
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RE: Red Arrow Hawk
Tom,
Again, we feel bad for your loss. We respectfully for your decision about Skymaster production. As you said hope someday your will have chance to see more Skymaster planes and have better view of our products. Please keep in mind, our offer always stand. Rob, I understand your disappointment that we are unable to give your friend a free plane. As I explained before, we take responsibility for any products defects. However, if it’s not a product defect we can’t just afford to give free planes to everyone who loses their plane. Your comments and suggestions, we always appreciate anything that can help us improve our products and customer service. However, if you can calm down and read my post carefully, I explained that we have sold close to 1000 planes. There have been occasions that there were product defects, and for every plane that is damaged, we take responsibility for. Just to make things clear, Tom confirmed that the wing itself did not flutter. It was the aileron that fluttered. As far as your example of another manufacturer’s (Viper Jet) response to their customers, are you sure you’d like us to give the same type of service and responded? You may want to search RCU to see how many of those planes have crashed and what type of response the customers received. I just want to make sure that you know it clear. There are currently over 100 Hawks that are being flown. A lot of Hawk have been flown in front of a crowd. I provided a few links for you guys to see how the planes perform. Please take a look if you’re interested. http://www.airpacmodels.com/media/videos/ali_t45.wmv http://www.airpacmodels.com/media/videos/ali_t45_2.wmv Also SKS video Florida Jet 2005 Jose, From the picture you’ve provided, this plane is a bad apple. Please send me an email directly and I’ll work something out for you to compromise for your loss. Skymaster is still a young company and needs more room to grow. If you guys have any suggestions or comments, you are always welcomed to call or email me. |
RE: Red Arrow Hawk
Hi
I have been reading these posts with interest and have not really had my own post regarding engine size and weight answered as yet as everyone seems to be embroiled in the "Flutter post " issue, ( for which I have a lot of sympathy). I am seroiusly thinking of ordering one of these kits from Ali but am now a little apprehensive regarding the "FUS stick" quality and the aileron issue. In the Jet mag article David Gladwin also shows the front U/C former is out of square and other non stick issues. Todd what garuntee can you give me that any kit I buy in the UK will have had these issues addressed. Is there a production number after which things have been improved or is it not as simple as that. I appreciate whilst this kit is ARF I would do some modelling so to speak whilst fitting it out but not retro reconstruction as this is never as easy as doing it right from the begining. Normally access then becomes a real issue. I am kean to go forward on this project but any comments you may have on the above would be usefull. Thanks David |
RE: Red Arrow Hawk
David Hi,
The answer to your question is quite hard to give. There is no specific batch date from when quality suddenly gets better. My experience of the last order of hawks that I received was pretty positive. I estimate at around 90% of the hawks that I sold were spot on and sell able. About 5% had manufacturing defects that were purely cosmetic and 5% has defects that I judged made the model unsellable. Out of this 5% every single part that was defective has now been replaced by the factory (No questions asked) It is a strange thing these ARTF jets. What one customer will live with as acceptable another will raise hell over. A classic example of this is shown in my own demo model. This was infact a model that the customer returned to me for a refund. He also had a misaligned front former, a paint chip in the fuselage moulding and marks on the mouldings of the wings and stabs. I took this model and gave it a flat with rubbing compound. Then polished it with car polish. This took care of the marks and gave an amazing gloss finish. The Paint chip I Touched in with red Enamel paint and the front former was left alone. Anybody that sees my model I am sure will back me up on the finish and the performance of this jet. Yes in a perfect world there would be no defects in ARTF jets but I cant see how this is possible with the manufacturing process that we use for making models. I myself have purchased ARTF jets from well established jet manufactures that cost 3 times that of the Hawk and these still had surface defects and as became apparent design faults that lead to structural amendments being made. So I dont think it is fair to single out Skymaster as an inferior product. One last point I will make in Skymaster defense is that they have always been very happy in helping customers with trying to resolve any issues that arise. If you have any questions please feel free to contact me through the usual route or just drop a direct question into the thread. I think like all of the other Skymaster dealers I am quite open and willing to aknowledge that the product that we sell is not perfect, and I enjoy working with all the team at Skymaster in the constant effort to improve. |
RE: Red Arrow Hawk
:DNow thats great customer service. I just got off the phone with Eric from AirPac Models and I'm happy to say that he will be taking care of my problems with my Hawk. Thats more than I could say about other companies. I once brout a tune pipe from a well known compamy and after two flights on my Sabre the pipe broke in half and all I got was sorry[:o]. I was told that happens because of the vibration. Now I will never buy any jets from that company which I am sure it's no lost to them.
But I have to say what AirPac is for me is greatly appreciated and thats the way customer service should be. Thanks Eric. |
RE: Red Arrow Hawk
when setting the turbine in place, is there a recomended space that should be between the front of the turbine and the fiberglass inlets? i have noticed in some pics, guys have even cut the inlets aloowing the turbine to sit more forward, and i have also seen pics with the nose of the turbine deep inthe inlets. which is best?
mark should have mine ready to test fly in a week, maybe at fentress when the meet is over? |
RE: Red Arrow Hawk
Anyone have a link to some Hawk drawings that show good detail on the wing fence size and locations? Thanks.
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RE: Red Arrow Hawk
Hi there,Just reading some of the Hawk stories.
Could you tell me how the stall occured? was it at actual low speeds,during landing or normal flight. Or did it occur at higher speed. A friend of mine lost a hawk to in a situation what looks a tip stall but at a speed higher speed. regards Hans |
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