Theoretic model
01-24-2009, 08:17 PM
#26
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RE: Theoretic model
A good point and something I had not thought of: fatigue issues. On full scale, you inspect for a min flaw size and perform analytical methods to ensure that the biggest undetected flaw cannot grow to failure during service life. How the heck are ya gonna do that with these thin sheets??? Ya gonna X-ray & dye pen them? I don't think so. This could be a huge issue! It can be aleviated by using thicker material, but then there is that weight thing again!!!
01-24-2009, 08:53 PM
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RE: Theoretic model
I wonder what the time frame for such defects to form is. I think it’s going to be a case of your going to see it and take care of it before it becomes a problem or you are not. I was pondering the idea of creating a composite skin like GLARE, using 1layer of .1mm aluminum, 1 layer of .1mm glass fiber or carbon fiber and resin and 1 layer of .1mm aluminum. That would greatly reduce the possibility of stress fractures. Also there is much more support structure in a fighter aircraft design that a commercial airliner for example.
ORIGINAL: Woketman
A good point and something I had not thought of: fatigue issues. On full scale, you inspect for a min flaw size and perform analytical methods to ensure that the biggest undetected flaw cannot grow to failure during service life. How the heck are ya gonna do that with these thin sheets??? Ya gonna X-ray & dye pen them? I don't think so. This could be a huge issue! It can be aleviated by using thicker material, but then there is that weight thing again!!!
A good point and something I had not thought of: fatigue issues. On full scale, you inspect for a min flaw size and perform analytical methods to ensure that the biggest undetected flaw cannot grow to failure during service life. How the heck are ya gonna do that with these thin sheets??? Ya gonna X-ray & dye pen them? I don't think so. This could be a huge issue! It can be aleviated by using thicker material, but then there is that weight thing again!!!
01-25-2009, 02:50 AM
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RE: Theoretic model
I have seen charts and data, but they are dealing with the full sized aircraft. I don't think that data deals with scale applications. As hobbyist we are dealing with unknowns. Unfortunately the military benefits from our experiences in terms of drones and UAVs but we do not share the same luxury.
ORIGINAL: Woketman
The time frame is determined by load, cycles, temperature, cycles, etc. Any skin, be it metallic, or composite, or a combo has to be analysed, based on test data, as to its fracture properties to determine life.
The time frame is determined by load, cycles, temperature, cycles, etc. Any skin, be it metallic, or composite, or a combo has to be analysed, based on test data, as to its fracture properties to determine life.
01-25-2009, 06:36 AM
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RE: Theoretic model
I am surprised that the scale wieght you have come up with is so out of whack. The full scale scale weighs 38000 dry and unladen. You forget that the plane is built for two things, to carry and keep safe the pilot, also to carry and guide weapons. When you remove those two factors the weight of the plane is diminished by a huge factor. The plane does not have to have the added weight structurally to carry the huge weapon weights so can be reduced exponentially. The pilot himself with his g suit etc has to have parachutes, life rafts, oxygen etc and the seat has to be built to support that. The whole weight of the life support capsule and armour and the area to support that amount of weight is lost.No redundancy of systems,or fire suppression equipment, no life support or communication. In sum the weight of any war plane with all that removed could be built so much lighter. Remove all that and the weight of what you remove is compounded by the weight of the support structure that is no longer needed. A scale weight for your plane even scaling down from a more reasonable 19000 pounds would be in the 150 pound range and could still be over built.
The skin will most likely have to be a little thicker than scale but would be easily doable. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
This is another all metal model http://www.zenithair.com/stolch801/b...os-rangal1.jpg
It is definitely doable but the work and learning will be the immense. I hope you do it but you will have to think like an engineer.
good luck
Paul
The skin will most likely have to be a little thicker than scale but would be easily doable. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
This is another all metal model http://www.zenithair.com/stolch801/b...os-rangal1.jpg
It is definitely doable but the work and learning will be the immense. I hope you do it but you will have to think like an engineer.
good luck
Paul
01-25-2009, 07:27 PM
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RE: Theoretic model
Do you really think removing those systems would account for a 50% weight reduction? I was assuming the removal of those systems and being replaced by RC components would only net me a 20% weight savings. Also do you have any more information on "the South American guy", I would like to see his work.
Thanks
Bill
Thanks
Bill
ORIGINAL: dragoonpvw
I am surprised that the scale wieght you have come up with is so out of whack. The full scale scale weighs 38000 dry and unladen. You forget that the plane is built for two things, to carry and keep safe the pilot, also to carry and guide weapons. When you remove those two factors the weight of the plane is diminished by a huge factor. The plane does not have to have the added weight structurally to carry the huge weapon weights so can be reduced exponentially. The pilot himself with his g suit etc has to have parachutes, life rafts, oxygen etc and the seat has to be built to support that. The whole weight of the life support capsule and armour and the area to support that amount of weight is lost.No redundancy of systems,or fire suppression equipment, no life support or communication. In sum the weight of any war plane with all that removed could be built so much lighter. Remove all that and the weight of what you remove is compounded by the weight of the support structure that is no longer needed. A scale weight for your plane even scaling down from a more reasonable 19000 pounds would be in the 150 pound range and could still be over built.
The skin will most likely have to be a little thicker than scale but would be easily doable. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
This is another all metal model http://www.zenithair.com/stolch801/b...os-rangal1.jpg
It is definitely doable but the work and learning will be the immense. I hope you do it but you will have to think like an engineer.
good luck
Paul
I am surprised that the scale wieght you have come up with is so out of whack. The full scale scale weighs 38000 dry and unladen. You forget that the plane is built for two things, to carry and keep safe the pilot, also to carry and guide weapons. When you remove those two factors the weight of the plane is diminished by a huge factor. The plane does not have to have the added weight structurally to carry the huge weapon weights so can be reduced exponentially. The pilot himself with his g suit etc has to have parachutes, life rafts, oxygen etc and the seat has to be built to support that. The whole weight of the life support capsule and armour and the area to support that amount of weight is lost.No redundancy of systems,or fire suppression equipment, no life support or communication. In sum the weight of any war plane with all that removed could be built so much lighter. Remove all that and the weight of what you remove is compounded by the weight of the support structure that is no longer needed. A scale weight for your plane even scaling down from a more reasonable 19000 pounds would be in the 150 pound range and could still be over built.
The skin will most likely have to be a little thicker than scale but would be easily doable. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
This is another all metal model http://www.zenithair.com/stolch801/b...os-rangal1.jpg
It is definitely doable but the work and learning will be the immense. I hope you do it but you will have to think like an engineer.
good luck
Paul
01-26-2009, 01:59 PM
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RE: Theoretic model
I assume you are refering to the AMA weight and thust limits. This potential build may not be eligible for competition according to their guidlines, that said it is not about competition for me rather a study in a different modeling technique. Is there some other governing body that would prohibit me from flying this model if it were produced that I am uanawre of?
ORIGINAL: Wayne22
Is this project meant to fly? If so, where (at that weight)?
Is this project meant to fly? If so, where (at that weight)?
01-26-2009, 11:22 PM
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RE: Theoretic model
Is this the guy?[link=http://www.rojasbazan.com/]South American Guy[/link]
ORIGINAL: dragoonpvw
. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
01-27-2009, 12:54 AM
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RE: Theoretic model
ORIGINAL: Bill W G S
Is this the guy?[link=http://www.rojasbazan.com/]South American Guy[/link]
Is this the guy?[link=http://www.rojasbazan.com/]South American Guy[/link]
ORIGINAL: dragoonpvw
. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
. Find the south American guy that builds his scale models out of metal. They are not much more in weight than standard balsa construction and are not flimsy to handle.
The formers and trusses for the airframe could be built tin the same locations as the full scale, and constructed as he does by pressing the parts. The strutural rigidity coming from the addition of the sheeting. I am not sure of his reivetting method as I remember that was one of his initial scale problems. I think he solved it though.
01-28-2009, 03:49 PM
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RE: Theoretic model
Having researched modeling sites that discussed full aluminum construction, I can across this:[link=http://translate.google.com/translate?ie=UTF8&oe=UTF&u=http%3A%2F%2Fwww.mhm-scale-aircraft.com%2Findex.php%3Fmid%3D25%23top&hl=en&ie =UTF8&sl=de&tl=en]Mhm Scale Aircraft[/link] I think the pictures answer many questions.
Also it appears that Germany has added a 25-150kg weight class for model aircraft. So while I would not be able to fly this proposed model in competition in America I could go to Deutschland. I've been many times and beer is fantastic!
Also it appears that Germany has added a 25-150kg weight class for model aircraft. So while I would not be able to fly this proposed model in competition in America I could go to Deutschland. I've been many times and beer is fantastic!
