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RE: Tomahawk-Design Bae Hawk 1: 3.5
Hmmm that's very interesting, I lost my Airworld Hawk when the fin came off, the break looked much like yours.
m |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: mick15 Hmmm that's very interesting, I lost my Airworld Hawk when the fin came off, the break looked much like yours. m Mick; Sorry to hear you lost your plane... But can you tell us some detail? Total flights, speed when it happend, manouvers, etc? Thanks in advance. Roar Jets of Norway |
RE: Tomahawk-Design Bae Hawk 1: 3.5
I have owned 2 Skygate Hawks, and have flown 3 others. I have 3 friends that own them who fly quite often, and then I would guess at having seen maybe another 5-10 fly a ross the world on my travels. The only time I have ever seen an issue with the rudder was on the prototype model when it was first released at the jet masters. That issue was a result of the rudder servo failing and causing flutter in the entire fin. I know as I watched Stephen Volker replace the servo on more than one occasion, go out and do another flight. Only for the same result. Half way through the flight as the rudder was loaded the servo or something in the servo set up would fail and always with the same result. Sorry but I do not thnk it is a model issue.
Mick, dont get me started o how many Airworld hawks I have owned, flown or seen fly with no issue what so ever. :D:D I see it more and more often where the larger planes are flown in the same way as the smaller jets ( hard ) most of the time the pilot gets away with it, but sometimes not. At the last jet meeting I was at I watched a very competent pilot, who normally flies mainly smallish sport jets ( Bandits, etc ) Fly his new MB339. He was flying it really well, but just a little to " Hard" in my opinion. I went over and had a word with him, just offering some advice and trying to explain how these large heavy scale models have so much inertia behind them that it's easy to let the speed build up, and then when flown in the same manner as a sport jet that can be pulled and pushed much harder the loads are so great it can cause a failure. He took the advice on board and will hopefully get any enjoyable flights on that model. I am just getting into full size flying and as part of it I am trying to fly as many different types as I can. The thing that amazes me is the different VNE's ( Velocity never to be exceeded) There are. Its amazing that two very similar looking aircraft can have such differing VNE's! I think its the same with models. For example.. I have seen people fly jets like Bandits, and Bobcats so , so hard with no issues. Yet I have seen models such as big L-39's and large deltas fold up like a paper bag mid flight in what looked to be a pretty tame flight. It's so difficult to give a comprehensive answer without going too technical. it's also so difficult giving a defined limit for each model. As most manufacturers do not test to destruction, and no models that I know of have a VNE. Even if they did how would we measure and monitor that we did not exceed them? For me the way I try to work round it is I try to adopt a different style of flying for each model. I have flown and will quite confidently fly a model such as my BVM Bobcat much harder, faster and more aggressively than I would something like my Skygate Hawk. I try and avoid mixing speed with high G maneuvers. Yes I do some pretty damn fast high speed runs, but I work up to these ( during flight testing away from a show environment before I get flamed ) I also do some high energy sharp pulls, but these I do turbine spooled down. I know for sure that if I mixed both those two aspects f my flight that it would be Bye Bye Bobcat! The same as when I fly my Skygate hawk ( P-180 powered by the way ) As soon as I am off and cleaned up I am back on the throttle, and I am using that throttle stick nearly as much as some of my flight controls. I watched a Skygate fly in Italy once and the only thing that saved it was the fact it flamed out. The pilot took off and from the moment he took off till the moment it flamed out the pilot never once touched the throttle stick ( No I could not see it but I sure could hear it) The model got faster and faster till it reached it's maximum speed. I was fearing the worst as the pilot was just getting settled in and I thought if he goes for any vertical maneuvers this could be curtains. Luckily the turbine shut down just as he was pulling 45 for what looked as it it might have been a half reverse cuban ( Which I think might have been the first and last time for that model ) After a perfect landing I went up to the pilot and tried to explain that he might try and adopt some throttle management, to which he informed me that he was famed in his local club for flying pulse jets ( No throttle ) and he had never had one of those fail. I did try to explain to him that a small pulse jet delta, although flying fast does not have the same flight loads on the surfaces or controls as this big hawk... Not sure what the outcome was but I am hoping that all went well. Sorry to waffle on guys, and please dont treat this as me pointing fingers, and having a preach. I am simply just trying to convey some of my experiences ( Good and bad ) As well as some of my worries. If I can ever be of any help, or give ay advice then please feel free to get in touch. Regards Al |
RE: Tomahawk-Design Bae Hawk 1: 3.5
RoLe, yes I was doing a public display and it was very windy (turbulent) I was halfway through the flight I carried out a four point roll and got to the 3rd quarter and when I applied top rudder the fin came off I not sure whether it fluttered first it was too far away to tell.
I seldom flew the mode flat out and it had had some 60 to 70 flights the fin snapped like yours and broke the carbon stern post. I haven’t been much help really only to wonder whether there sometimes are some peculiar aerodynamic forces, this is not the first model Hawk to suffer this end. m http://www.youtube.com/watch?v=vQDMRzbjahw |
RE: Tomahawk-Design Bae Hawk 1: 3.5
We published an airworthines advisory in the AW hawk build thread last summer after Mick lost his Hawk. My first Hawk had the fin structure fail at the fuselage area but the fin did not detach. Both of my Hawks now have received considerable strengthening in this area and I would advise the owners of any Hawks to take a careful look at this area, the Hawk fin is a very large and powerful surface and the AW fin spar is marginal at best. I will certainly strengthen the fin of my Skygate Hawk to comfort level and the model will be flown like I was in it !
Perhaps we are paying the price of trying to build larger and larger models whilst keeping the weight under the 20 k WJM limits. Thanks to Marc s and Schroedm for the advice, I think the Tomahawk would just be too big for me so I wll keep my AW Hawks, which fly so well, and the Skygate machine. It might also be worth mentioning that inflight loads can be very considerably increased in rough air. (as I was reminded descending through rotor turbulence in a Discus in New Zealand recently , I was convinced the thing was about to break up ! Regards, David Gladwin. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
1 Attachment(s)
It is today "cutting day"http://www.rcuniverse.com/forum/js/f...ngue_smile.gif
The hawk is going on liposuction. The front is ready now the rear. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: tobba People Looking for thoughts. I have a Tomahawk Hawk on order, due March. Keen for thoughts on the rudder setup. From everything I am hearing the Tomahawk is pretty much identical to the SG. I saw a near disaster here in New Zealand with a SG Hawk on its second flight a month or so ago. This model was built by a chap that has been flying and building for many years, including many Jets. I did not view the rudder setup first hand, but I would expect it to be correctly setup. I am aware of a similar issue on the prototype SG Hawk but have heard nothing since. Maybe future kits were upgraded? This is a big surface. Does it need 2 servos? Does it need a double arm - rigid push pull? or maybe more strengthening around the rudder tube where it mounts to the fuse? I am far from questioning the caliber of the design of either the SG or Tomahawk models - they are the best of the best, hence me buying one...! However the result on this model was a little disheartening. See a few shots attached of the damage to the SG Hawk. One prior to the incident. These guys were very lucky. Just managed to squeeze it back on the runway. Thoughts would be appreciated. I never had any issues with my SG Hawk but I 100% agree with Ali regarding 'hard' flying - I always looked to fly smoooth as was conscious of the loads on a big airframe. The Tomahawk is another step up above the SG Hawk so smoothness is of paramount importance. If I pulled hard or flew it like a sport jet and the airframe failed the first thing I'd be moaning about would be me! I too saw Stefan's fin flutter on the prototype so did ensure my fin setup on the SG was thoroughly aeropoxied - hence the rather embarrassing picture somewhere of the aeropoxy avalanche around my fin tube...... [8D] Let us know. Cheers, Mark |
RE: Tomahawk-Design Bae Hawk 1: 3.5
I think there are 2 different areas to talk about here, how models are flown and how they are manufactured.
It's interesting to see how the Hawk has become quite common now with many of the major manufacturers producing versions in ever increasing scale sizes. By it's very nature flying practice should evolve to more closely mimick that of full size versions but from what I have seen this does not seem to be happening. Although the manufacturers are controlling weight as sizes increase this would not be a good thing if the cost was compromised strength. It would be nice to know if any of the manufactuers carry out structural testing/health monitoring as part of the development process? I have not seen any Hawk flown scale, there is always some portion of the flight that is non scale, this in some cases may be unavoidable due to the nature of the flying site. The size of this non scale portion varies between the length of the entire flight down to maybe a few seconds. Non of these comments are aimed at any individual or manufacturer, just simple observations designed to add to the constructive posts already made. Rob. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Hi Mark,
2 flights - maiden and one more. Both very low key, calm and collected. I agree with all comments - these aircraft are under some serious loads and much respect should be applied when flying. A more scale approach seems all important. I will be doing some pretty erious strengthening on mine. I have no weight limit to hit, and strength and longevity are far more important to me. I can't help but thinking the comp 20kg weight limit is being delivered through some pretty excessive lightening. In my humble opinion I think both of the larger hawks could do with some extra weight... more fuel, fully ducted and some extra strengthening to start. The Airworld Hawk for example, with a higher wing loading, looks more sold in the air to me. Looking forward to my kit arriving. Big ups to the excess aeropoxy! |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: Robrow I think there are 2 different areas to talk about here, how models are flown and how they are manufactured. It's interesting to see how the Hawk has become quite common now with many of the major manufacturers producing versions in ever increasing scale sizes. By it's very nature flying practice should evolve to more closely mimick that of full size versions but from what I have seen this does not seem to be happening. Although the manufacturers are controlling weight as sizes increase this would not be a good thing if the cost was compromised strength. It would be nice to know if any of the manufactuers carry out structural testing/health monitoring as part of the development process? I have not seen any Hawk flown scale, there is always some portion of the flight that is non scale, this in some cases may be unavoidable due to the nature of the flying site. The size of this non scale portion varies between the length of the entire flight down to maybe a few seconds. Non of these comments are aimed at any individual or manufacturer, just simple observations designed to add to the constructive posts already made. Rob. Thats why the 20kg limit is so important to the German flyers, it's not only the competition limit, but also the limit for large model airplanes where you don't need certification (load testing etc.) in their country. In Belgium this limit is 25kg, our national aeronautics board does not test an airplane on structural integrity, we need to have it done in another country. This mostly happens in France at the "Le Petit Gros" airshow in La Ferté Alais. Beeing involved in building a few 30kg+ airplanes myself I know the requirements for it. During certification flights the days before the show there are always multiple Germans having their airplane certified there instead of their own country just because the French certification is much easier to do then the German. I can easily understand German manufacterers making bigger and bigger (WJM winning) models whilst desperately trying to stay under 20kg. Going over would not only mean "off-spec" for competition but more important exposing yourself to certification and lots of paperwork. Bart. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
From a builders point of view having just completed the rudder instal on an SG Hawk the cutout for the rudder linkage does require a small amount of material to be removed from the main vertical former where the hinges mount to, so structurally you are inducing a weak point in the fin skin around half way up with the cutout for the rudder linkage, and then slightly weakening the former in this area as well. Possibly not the most ideal set-up, maybe a pull pull at the fin/rudder base might be a more suitable fix?
marcs |
RE: Tomahawk-Design Bae Hawk 1: 3.5
1 Attachment(s)
I am ready with all the cutting.
It was a full day workhttp://www.rcuniverse.com/forum/js/f...bananahead.gif But the result is great. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Nice work!
The quality of the moldings looks superb (as the price indicates they should be!) Rgds, Mark |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Ali’s comments are well taken and essentially true but the real speed that is at issue here is not the VNE but the VA speed (Max. Maneuvering Speed) which is the maximum structural speed for full control deflection. It is much more likely that structural damage will occur at speeds well below VNE with our models especially if we are doing max control deflection maneuvering at even moderate speeds. What is more interesting is that structural failure can occur at speeds below VA…especially to the vertical fin...with max control deflections as was evidenced by the AA Airbus accident in NY in 2001. Fast knife-edge passes and four-pint rolls could be such a situation. I am not an aero engineer and many here could add to this but if you are interested, here is a pretty interesting account of that circumstance:
George http://www.flyingmag.com/myth-maneuvering-speed |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: Ali I have owned 2 Skygate Hawks, and have flown 3 others. I have 3 friends that own them who fly quite often, and then I would guess at having seen maybe another 5-10 fly a ross the world on my travels. The only time I have ever seen an issue with the rudder was on the prototype model when it was first released at the jet masters. That issue was a result of the rudder servo failing and causing flutter in the entire fin. I know as I watched Stephen Volker replace the servo on more than one occasion, go out and do another flight. Only for the same result. Half way through the flight as the rudder was loaded the servo or something in the servo set up would fail and always with the same result. Sorry but I do not thnk it is a model issue. Mick, dont get me started o how many Airworld hawks I have owned, flown or seen fly with no issue what so ever. :D:D I see it more and more often where the larger planes are flown in the same way as the smaller jets ( hard ) most of the time the pilot gets away with it, but sometimes not. At the last jet meeting I was at I watched a very competent pilot, who normally flies mainly smallish sport jets ( Bandits, etc ) Fly his new MB339. He was flying it really well, but just a little to '' Hard'' in my opinion. I went over and had a word with him, just offering some advice and trying to explain how these large heavy scale models have so much inertia behind them that it's easy to let the speed build up, and then when flown in the same manner as a sport jet that can be pulled and pushed much harder the loads are so great it can cause a failure. He took the advice on board and will hopefully get any enjoyable flights on that model. I am just getting into full size flying and as part of it I am trying to fly as many different types as I can. The thing that amazes me is the different VNE's ( Velocity never to be exceeded) There are. Its amazing that two very similar looking aircraft can have such differing VNE's! I think its the same with models. For example.. I have seen people fly jets like Bandits, and Bobcats so , so hard with no issues. Yet I have seen models such as big L-39's and large deltas fold up like a paper bag mid flight in what looked to be a pretty tame flight. It's so difficult to give a comprehensive answer without going too technical. it's also so difficult giving a defined limit for each model. As most manufacturers do not test to destruction, and no models that I know of have a VNE. Even if they did how would we measure and monitor that we did not exceed them? For me the way I try to work round it is I try to adopt a different style of flying for each model. I have flown and will quite confidently fly a model such as my BVM Bobcat much harder, faster and more aggressively than I would something like my Skygate Hawk. I try and avoid mixing speed with high G maneuvers. Yes I do some pretty damn fast high speed runs, but I work up to these ( during flight testing away from a show environment before I get flamed ) I also do some high energy sharp pulls, but these I do turbine spooled down. I know for sure that if I mixed both those two aspects f my flight that it would be Bye Bye Bobcat! The same as when I fly my Skygate hawk ( P-180 powered by the way ) As soon as I am off and cleaned up I am back on the throttle, and I am using that throttle stick nearly as much as some of my flight controls. I watched a Skygate fly in Italy once and the only thing that saved it was the fact it flamed out. The pilot took off and from the moment he took off till the moment it flamed out the pilot never once touched the throttle stick ( No I could not see it but I sure could hear it) The model got faster and faster till it reached it's maximum speed. I was fearing the worst as the pilot was just getting settled in and I thought if he goes for any vertical maneuvers this could be curtains. Luckily the turbine shut down just as he was pulling 45 for what looked as it it might have been a half reverse cuban ( Which I think might have been the first and last time for that model ) After a perfect landing I went up to the pilot and tried to explain that he might try and adopt some throttle management, to which he informed me that he was famed in his local club for flying pulse jets ( No throttle ) and he had never had one of those fail. I did try to explain to him that a small pulse jet delta, although flying fast does not have the same flight loads on the surfaces or controls as this big hawk... Not sure what the outcome was but I am hoping that all went well. Sorry to waffle on guys, and please dont treat this as me pointing fingers, and having a preach. I am simply just trying to convey some of my experiences ( Good and bad ) As well as some of my worries. If I can ever be of any help, or give ay advice then please feel free to get in touch. Regards Al http://www.youtube.com/watch?v=03RXm...eature=related |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: STKNRUD What is more interesting is that structural failure can occur at speeds below VA…especially to the vertical fin...with max control deflections as was evidenced by the AA Airbus accident in NY in 2001. Fast knife-edge passes and four-pint rolls could be such a situation. I am not an aero engineer and many here could add to this but if you are interested, here is a pretty interesting account of that circumstance: George http://www.flyingmag.com/myth-maneuvering-speed Many Boeing airliners use a rudder ratio unit that reduces max rudder angle, travel, when speed is above around 210 knots to prevent fin overload. I simulated this, to a degree, on my AW Hawks by using Flight Modes such that in the flaps up, higher speed, config, the max rudder angle is reduced to about 2/3rds the travel when the flaps are out and speed is lower. The max travel, flaps up, is determined by the amount of rudder required in slow and 4 point rolls at moderate speeds using full stick deflection. Works well and I am sure this is what prevented fin separation on my Hawk when the fin spar failed. Regards, David Gladwin PS I wonder if any of the WING failures on some ARTFs (as referred to by Ali) have been caused by rolling G where coarse aileron application whilst pulling high G can cause even further G loading on the upgoing wing to the point of overload and failure ? It was a limitation on the Jet Provost as the use of coarse aileron above 4 g was prohibited. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: RUFTER Thats why the 20kg limit is so important to the German flyers, it's not only the competition limit, but also the limit for large model airplanes where you don't need certification (load testing etc.) in their country. I can easily understand German manufacterers making bigger and bigger (WJM winning) models whilst desperately trying to stay under 20kg. Going over would not only mean ''off-spec'' for competition but more important exposing yourself to certification and lots of paperwork. I have heared many people say that a AW hawk flyes better (scale) than the bigger ones. I have flown an AW Hawk that is about 22 kg dry, and even that one feels a little to light... |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Staale thats exactly what Ali commented on and why the SG Hawk I am building for a client currently is not going to be anywhere close to 20kg, a larger tank for fuel, smoke tank and a fully ducted system from inlets through to tail pipe are just a few mods, the ducting and tank options will also be transferred to the Tomahawk Hawk on the next build as well to increase the weight to a more realistic level...
marcs |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Ok, the flight speed envelope is not scale,
but they are BEATIFULL. Regards Nuno |
RE: Tomahawk-Design Bae Hawk 1: 3.5
1 Attachment(s)
The new engine is in the hous for the Hawkhttp://www.rcuniverse.com/forum/js/f...unge_smile.gif
It is a brand new "AMT Olympus Hp nl" turbine. Enough power i think |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Certainly our models are not designed with the same attention to structural requirements, fatigue testing, etc. as full-scale. Rather they are more likely designed with a lot of 'hindsight' of what worked (or didn't) on the last model. Computerized rudder movement limits that David referred to are required largely because, unless you are sitting in the rear of the airliner, the pilot can not imagine the stress that rudder movement creates compared to elev and ail inputs....he can't feel them because he is only a couple feet behind the nose. If the pilot of an airliner leaves the rudder dampner off during turbulence, the rear of the plane will fill with barf while he's enjoying a cup of coffee. The same is true of our models. We have a sense of the stress induced by abrupt ail and elev inputs but we can't "feel" them and most RC flyers probably believe that side-to-side rudder movements are of no consequence to structural integrity....and they are, even at moderate speeds. Likewise, there is probably less focus by our model designers on the vert fin integrity as there is on the wing and horz stab. I am surprised that we don't experience more vert fin failures considering the weight of our jets and the number of knife-ege passes and other rudder intensive maneuvers that are done with them. This forum through the experience of others, is the best feedback we and the designers can get about the any model's weakness.
George |
RE: Tomahawk-Design Bae Hawk 1: 3.5
Is it not better to fly this bird first (Tomahawk Hawk) beforeyou "SPECULATE" of the airframe is strong enough.http://www.rcuniverse.com/forum/js/f...wink_smile.gif I thinkthat Thomas fly many and many thimes with the hawk before he make a kit ofithttp://www.rcuniverse.com/forum/js/f.../msn/72_72.gif best regards Maikel</p> |
RE: Tomahawk-Design Bae Hawk 1: 3.5
ORIGINAL: butler-campers Is it not better to fly this bird first (Tomahawk Hawk) before you ''SPECULATE'' of the airframe is strong enough.[img][/img] I think that Thomas fly many and many thimes with the hawk before he make a kit of it [img][/img] best regards Maikel</p> Hmmmm....I don't think I "speculated" about any kit, including this particular one. Not-with-standing that, I think it is appropriate for us to "speculate" or comment on just about anything since it is particularly hard to determine definitively about a lot of problems (like static, and many others). Maybe others have had a similar problem...maybe someone will refute it and add some useful information, etc. I think there are very few comments posted on RC that are intended to condemn a particular kit or component. If there are a few, I think most can see through it and/or you will see comments that are in opposition to the condemnation. I'd rather hear it all before I buy and fly and make-up my own mind. George |
RE: Tomahawk-Design Bae Hawk 1: 3.5
I honestly don't understand the obsession for theese large and supelight planes. I think a SG Hawk at 20 kg looks ridiculous in the air scale vise. And I don't understand how they could win a competition when they fly like big depron park flyers?? A Hawk does not hover in at the landing approach like the Germans do with their SG Hawk, or fly knife-edge at 30 mph. For a SG Hawk to look scale in the air it would need maybe 10-15 kg of ballast, so how heavy would the Tomahawk one need to be to fly scale? 40-50 kg or 90 - 110 lbs maybe?? I have heared many people say that a AW hawk flyes better (scale) than the bigger ones. I have flown an AW Hawk that is about 22 kg dry, and even that one feels a little to light... Craig. |
RE: Tomahawk-Design Bae Hawk 1: 3.5
I dont see what the issue is here. Just because they can be built under 20 KG does that mean we have to build them so?
I have just flown the best Skygate hawk and maybe even the best hawk I have ever flown. It's a un structurally modified kit but instead of a dry weight of 20 kg it is more like 24kg. I flew it in what I perceived to be a scale manner with various aeros including knife edge passes, knife edge circuits and even a knife edge to knife edge changeover. No problem what so ever. My only fault with it was the high drag and poor speed retention, and even that could be worked around with the extra thrust of the P-180 turbine. My Tomahawk when it comes will be built to a similar standard and weight. Hell I may even add some form of ballast box. I will also fit a fully ducted system with bypass ( As we are doing now for a customers Skygate Hawk ) Which I believe will make it fly even better and more like my Airworld and Skymaster hawks. Sure if you are that way inclined at the World Jet Masters means it all to you then go for it under 20 KG. Multiple wins and top five places over the past few years seems to show that light and floaty is what the judges want ( Dont get me started on this issue as I am with Sap on this one and to me it is this that forced me to lose interest in the event ) It goes back to a belief of mine that too many modelers are not prepared to tune/ adjust or tweek a model so it suits their own desires and flying styles. Hell The Skygate that I just flew came to me pre owned and the owner had set it up as per instructions... When I flew it I thought it was horrific. Great set up if I were flying a 3d style aerobatic plane and wanted a totally neutral model that required very little inputs to perfrom lets say an axial slow roll, but for a nice solid scale jet..... [:'(] |
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