FEJ f-86 crash at florida jet 2014
04-13-2014, 08:25 AM
#78
Senior Member
Join Date: Jan 2012
Location: South Florida
Posts: 375
Likes: 0
Received 0 Likes
on
0 Posts
I, and many others I know, simply use this site for reference, and to learn from the advise and mistakes of others ... regardless of whether they owned the jet or not. It's all valuable information, and consistent with that of others who made comments here.
My jet flying buddies and I have been flying R/C jets for 5 to 12 years, and ducted fan jets long before that. It amazes me that some people require others to "qualify" their statements by claiming that one has to own a particular jet to be able to discuss or criticize it. Following that thought, I suppose one can't talk about a heart attack or a stroke unless they experience one for themselves. Then, we can't talk about politics unless we are politicians. Nor can we discuss any topic in which we didn't own that item. So, don't talk about a Porsche unless you owned one, don't talk about a brand of car unless you owned that brand, make and model, don't talk about a restaurant unless you have eaten there ... that means don't tell your friend that your other friend told you that a particular restaurant served lousy food or had lousy service. If you have one principle, then it should follow through with all situations.
Can we get back to the topic on hand, please?
Last edited by BobbyMcGee; 04-13-2014 at 08:27 AM.
04-13-2014, 09:09 AM
#79
My Feedback: (11)
Join Date: Sep 2010
Location: marina del rey, CA
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
What drives people away from writing on these forums is the way people attack each other ... like the manner in which you are doing here. A reasonable discussion has turned into an attack. You live in another country. How can you make such wild claims and attacks?
I, and many others I know, simply use this site for reference, and to learn from the advise and mistakes of others ... regardless of whether they owned the jet or not. It's all valuable information, and consistent with that of others who made comments here.
My jet flying buddies and I have been flying R/C jets for 5 to 12 years, and ducted fan jets long before that. It amazes me that some people require others to "qualify" their statements by claiming that one has to own a particular jet to be able to discuss or criticize it. Following that thought, I suppose one can't talk about a heart attack or a stroke unless they experience one for themselves. Then, we can't talk about politics unless we are politicians. Nor can we discuss any topic in which we didn't own that item. So, don't talk about a Porsche unless you owned one, don't talk about a brand of car unless you owned that brand, make and model, don't talk about a restaurant unless you have eaten there ... that means don't tell your friend that your other friend told you that a particular restaurant served lousy food or had lousy service. If you have one principle, then it should follow through with all situations.
Can we get back to the topic on hand, please?
I, and many others I know, simply use this site for reference, and to learn from the advise and mistakes of others ... regardless of whether they owned the jet or not. It's all valuable information, and consistent with that of others who made comments here.
My jet flying buddies and I have been flying R/C jets for 5 to 12 years, and ducted fan jets long before that. It amazes me that some people require others to "qualify" their statements by claiming that one has to own a particular jet to be able to discuss or criticize it. Following that thought, I suppose one can't talk about a heart attack or a stroke unless they experience one for themselves. Then, we can't talk about politics unless we are politicians. Nor can we discuss any topic in which we didn't own that item. So, don't talk about a Porsche unless you owned one, don't talk about a brand of car unless you owned that brand, make and model, don't talk about a restaurant unless you have eaten there ... that means don't tell your friend that your other friend told you that a particular restaurant served lousy food or had lousy service. If you have one principle, then it should follow through with all situations.
Can we get back to the topic on hand, please?
I completely agree with you accept that I come on here to look around and gather information from others on many different makes and models of jets that i'm building flying or thinking of buying, when somebody comes here and constantly destroys threads with crazy statements and unsubstantiated ideas it prevents me and others from learning, it also prevents me and others from making informed decisions on what we want to put our money into.
I have an FEJ 103inch f18 right behind me as we speak, it is a pre honeycomb model and I have spent much time trawling through all threads here to gather all the information I can here to make informed decisions on what need to be done to make it flight worthy.
I have also spent a number of hours testing and checking the jet myself to asses it and decide what I need to do, here is what ive found.
the thrust pipe is rubbish, fortunately I have a tam version, I have bore scoped the wings and stabs, the wings are great, they have ribs every three inches the glue joints are perfect and they look very strong. the stabs have 3 ribs also but they are balsa as is the torque rod receiver (keep in mind that this is just how most manufacturers of the time did it) the fuselage looks great but lacks structural lateral bracing, im no engineer but when I see skymaster running carbon strips down the fuse on a smaller jet I think the FEJ should have it also.
I have everything I need to make this jet airworthy and really by the time im done it will be better in terms of strength than most mass produced jets.
All of this information could be available to others out there easily if it wasn't for the fact that people here just want to bash others, insult their income level and generally demoralize them for a decision they have made, informed or not.
Its a free country and everyone is entitled to their opinion but please make it clear weather its opinion based on what your read or opinion based on what you've experienced, I will tell anyone of my experience with my FEJ products if asked but would never have the audacity to speak of the company's whole product line based on my limited exposure. That's exactly whats happening here, this guy has not experienced every FEJ product he has no idea whats in my garage yet his expert mind is ready to cast judgment.
Why don't we make it a policy to ourselves to substantiate our comments with a note of our level of experience in that particular field.
04-13-2014, 09:11 AM
#80
My Feedback: (11)
Join Date: Sep 2010
Location: marina del rey, CA
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
I completely agree with you accept that I come on here to look around and gather information from others on many different makes and models of jets that i'm building flying or thinking of buying, when somebody comes here and constantly destroys threads with crazy statements and unsubstantiated ideas it prevents me and others from learning, it also prevents me and others from making informed decisions on what we want to put our money into.
I have an FEJ 103inch f18 right behind me as we speak, it is a pre honeycomb model and I have spent much time trawling through all threads here to gather all the information I can here to make informed decisions on what need to be done to make it flight worthy.
I have also spent a number of hours testing and checking the jet myself to asses it and decide what I need to do, here is what ive found.
the thrust pipe is rubbish, fortunately I have a tam version, I have bore scoped the wings and stabs, the wings are great, they have ribs every three inches the glue joints are perfect and they look very strong. the stabs have 3 ribs also but they are balsa as is the torque rod receiver (keep in mind that this is just how most manufacturers of the time did it) the fuselage looks great but lacks structural lateral bracing, im no engineer but when I see skymaster running carbon strips down the fuse on a smaller jet I think the FEJ should have it also.
I have everything I need to make this jet airworthy and really by the time im done it will be better in terms of strength than most mass produced jets.
All of this information could be available to others out there easily if it wasn't for the fact that people here just want to bash others, insult their income level and generally demoralize them for a decision they have made, informed or not.
Its a free country and everyone is entitled to their opinion but please make it clear weather its opinion based on what your read or opinion based on what you've experienced, I will tell anyone of my experience with my FEJ products if asked but would never have the audacity to speak of the company's whole product line based on my limited exposure. That's exactly whats happening here, this guy has not experienced every FEJ product he has no idea whats in my garage yet his expert mind is ready to cast judgment.
Why don't we make it a policy to ourselves to substantiate our comments with a note of our level of experience in that particular field.
I have an FEJ 103inch f18 right behind me as we speak, it is a pre honeycomb model and I have spent much time trawling through all threads here to gather all the information I can here to make informed decisions on what need to be done to make it flight worthy.
I have also spent a number of hours testing and checking the jet myself to asses it and decide what I need to do, here is what ive found.
the thrust pipe is rubbish, fortunately I have a tam version, I have bore scoped the wings and stabs, the wings are great, they have ribs every three inches the glue joints are perfect and they look very strong. the stabs have 3 ribs also but they are balsa as is the torque rod receiver (keep in mind that this is just how most manufacturers of the time did it) the fuselage looks great but lacks structural lateral bracing, im no engineer but when I see skymaster running carbon strips down the fuse on a smaller jet I think the FEJ should have it also.
I have everything I need to make this jet airworthy and really by the time im done it will be better in terms of strength than most mass produced jets.
All of this information could be available to others out there easily if it wasn't for the fact that people here just want to bash others, insult their income level and generally demoralize them for a decision they have made, informed or not.
Its a free country and everyone is entitled to their opinion but please make it clear weather its opinion based on what your read or opinion based on what you've experienced, I will tell anyone of my experience with my FEJ products if asked but would never have the audacity to speak of the company's whole product line based on my limited exposure. That's exactly whats happening here, this guy has not experienced every FEJ product he has no idea whats in my garage yet his expert mind is ready to cast judgment.
Why don't we make it a policy to ourselves to substantiate our comments with a note of our level of experience in that particular field.
I don't believe that negative comments from one to another drive people away, I think that people get driven away because they try to educate others and get shot down by clowns!
04-13-2014, 09:18 AM
#81
Hey Kim, on that F-18 one of the easy things you can do is verify that the stabilator pivot is properly placed. Getting this wrong makes everything else even more critical. If you need help PM me a top view photo of the stab or make a sketch I can double check it for you.
Second thing is to make sure you know the required stab throws so you can optimize the linkage (you get full throws with at least 100% ATV).
Second thing is to make sure you know the required stab throws so you can optimize the linkage (you get full throws with at least 100% ATV).
04-13-2014, 06:13 PM
#86
Lightning,
You want advice. Well here it is ...
Open up the stabs and completely rebuild them. The FEJ stab design/support structure is pure junk. The mere fact that the last (outboard) 7 or 8 inches is not reinforced with spars or ribs is a major contributor to flutter, and shows the lack of engineering on the part of FEJ (unless they designed it that way so you crash the jet and buy another one). When the jet reaches speeds of 80+ mph the flow of air actually collapses (compresses) the upper & lower skins to the point where the stab becomes a flat surface and has all the strength of corrugated cardboard. Then the flexing & flutter begins and the jet goes down. Run ribs every three inches and have at least one spar run to the tip. I’d use two, but that’s just me. Your second choice would be to make a foam core throughout, but use ribs & spars on the inner half. I’d balance the stabs too. But hell, what do I know, I’ve never owned an FEJ jet. I’ve only done this with other jets and never had problems. But obviously still don’t know what I’m talking about, right?
You want advice. Well here it is ...
Open up the stabs and completely rebuild them. The FEJ stab design/support structure is pure junk. The mere fact that the last (outboard) 7 or 8 inches is not reinforced with spars or ribs is a major contributor to flutter, and shows the lack of engineering on the part of FEJ (unless they designed it that way so you crash the jet and buy another one). When the jet reaches speeds of 80+ mph the flow of air actually collapses (compresses) the upper & lower skins to the point where the stab becomes a flat surface and has all the strength of corrugated cardboard. Then the flexing & flutter begins and the jet goes down. Run ribs every three inches and have at least one spar run to the tip. I’d use two, but that’s just me. Your second choice would be to make a foam core throughout, but use ribs & spars on the inner half. I’d balance the stabs too. But hell, what do I know, I’ve never owned an FEJ jet. I’ve only done this with other jets and never had problems. But obviously still don’t know what I’m talking about, right?
04-13-2014, 06:39 PM
#87
I completely agree with you accept that I come on here to look around and gather information from others on many different makes and models of jets that i'm building flying or thinking of buying, when somebody comes here and constantly destroys threads with crazy statements and unsubstantiated ideas it prevents me and others from learning, it also prevents me and others from making informed decisions on what we want to put our money into.
I have an FEJ 103inch f18 right behind me as we speak, it is a pre honeycomb model and I have spent much time trawling through all threads here to gather all the information I can here to make informed decisions on what need to be done to make it flight worthy.
I have also spent a number of hours testing and checking the jet myself to asses it and decide what I need to do, here is what ive found.
the thrust pipe is rubbish, fortunately I have a tam version, I have bore scoped the wings and stabs, the wings are great, they have ribs every three inches the glue joints are perfect and they look very strong. the stabs have 3 ribs also but they are balsa as is the torque rod receiver (keep in mind that this is just how most manufacturers of the time did it) the fuselage looks great but lacks structural lateral bracing, im no engineer but when I see skymaster running carbon strips down the fuse on a smaller jet I think the FEJ should have it also.
I have everything I need to make this jet airworthy and really by the time im done it will be better in terms of strength than most mass produced jets.
All of this information could be available to others out there easily if it wasn't for the fact that people here just want to bash others, insult their income level and generally demoralize them for a decision they have made, informed or not.
Its a free country and everyone is entitled to their opinion but please make it clear weather its opinion based on what your read or opinion based on what you've experienced, I will tell anyone of my experience with my FEJ products if asked but would never have the audacity to speak of the company's whole product line based on my limited exposure. That's exactly whats happening here, this guy has not experienced every FEJ product he has no idea whats in my garage yet his expert mind is ready to cast judgment.
Why don't we make it a policy to ourselves to substantiate our comments with a note of our level of experience in that particular field.
I have an FEJ 103inch f18 right behind me as we speak, it is a pre honeycomb model and I have spent much time trawling through all threads here to gather all the information I can here to make informed decisions on what need to be done to make it flight worthy.
I have also spent a number of hours testing and checking the jet myself to asses it and decide what I need to do, here is what ive found.
the thrust pipe is rubbish, fortunately I have a tam version, I have bore scoped the wings and stabs, the wings are great, they have ribs every three inches the glue joints are perfect and they look very strong. the stabs have 3 ribs also but they are balsa as is the torque rod receiver (keep in mind that this is just how most manufacturers of the time did it) the fuselage looks great but lacks structural lateral bracing, im no engineer but when I see skymaster running carbon strips down the fuse on a smaller jet I think the FEJ should have it also.
I have everything I need to make this jet airworthy and really by the time im done it will be better in terms of strength than most mass produced jets.
All of this information could be available to others out there easily if it wasn't for the fact that people here just want to bash others, insult their income level and generally demoralize them for a decision they have made, informed or not.
Its a free country and everyone is entitled to their opinion but please make it clear weather its opinion based on what your read or opinion based on what you've experienced, I will tell anyone of my experience with my FEJ products if asked but would never have the audacity to speak of the company's whole product line based on my limited exposure. That's exactly whats happening here, this guy has not experienced every FEJ product he has no idea whats in my garage yet his expert mind is ready to cast judgment.
Why don't we make it a policy to ourselves to substantiate our comments with a note of our level of experience in that particular field.
04-14-2014, 12:48 AM
#88
My Feedback: (11)
Join Date: Sep 2010
Location: marina del rey, CA
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
Lightning,
You want advice. Well here it is ...
Open up the stabs and completely rebuild them. The FEJ stab design/support structure is pure junk. The mere fact that the last (outboard) 7 or 8 inches is not reinforced with spars or ribs is a major contributor to flutter, and shows the lack of engineering on the part of FEJ (unless they designed it that way so you crash the jet and buy another one). When the jet reaches speeds of 80+ mph the flow of air actually collapses (compresses) the upper & lower skins to the point where the stab becomes a flat surface and has all the strength of corrugated cardboard. Then the flexing & flutter begins and the jet goes down. Run ribs every three inches and have at least one spar run to the tip. I’d use two, but that’s just me. Your second choice would be to make a foam core throughout, but use ribs & spars on the inner half. I’d balance the stabs too. But hell, what do I know, I’ve never owned an FEJ jet. I’ve only done this with other jets and never had problems. But obviously still don’t know what I’m talking about, right?
You want advice. Well here it is ...
Open up the stabs and completely rebuild them. The FEJ stab design/support structure is pure junk. The mere fact that the last (outboard) 7 or 8 inches is not reinforced with spars or ribs is a major contributor to flutter, and shows the lack of engineering on the part of FEJ (unless they designed it that way so you crash the jet and buy another one). When the jet reaches speeds of 80+ mph the flow of air actually collapses (compresses) the upper & lower skins to the point where the stab becomes a flat surface and has all the strength of corrugated cardboard. Then the flexing & flutter begins and the jet goes down. Run ribs every three inches and have at least one spar run to the tip. I’d use two, but that’s just me. Your second choice would be to make a foam core throughout, but use ribs & spars on the inner half. I’d balance the stabs too. But hell, what do I know, I’ve never owned an FEJ jet. I’ve only done this with other jets and never had problems. But obviously still don’t know what I’m talking about, right?
All great advice, the thing is my stabs are solidly built, the last 5 inches of the stab is solid wood (balsa) they have 3 more ribs across their 15.5 inch span, but yes if it was a honeycomb version this would be exactly the correct approach towards modifying and making this jet airworthy.
I will still open up the root and replace the balsa torque tube receiver with hardwood
Nobody is against constructive criticism of jet manufacturers etc so why cant this be the norm for everybody but it seems to have degraded to slagging off each other and each others possessions, there is a wealth of knowledge available so lets just pass it around.
I totally agree that once enough modifications have been made FEJ can no longer be given credit for the jet, I also agree that if they were a decent company they would be more responsible for their past, I also agree that we as a community should boycott them until they make things right, but I like many others already own the product and will make it airworthy and will do my best to help others achieve the same.
As a side note its not that unusual to have to modify aspects of most companies designs to get them to my standards, however it goes a little further with FEJ
Airplanes, I'm pleased that you could write a more restrained response than is often seen here and share your knowledge with others, now if everyone can follow suit this can be a really useful resource again
04-14-2014, 04:24 AM
#90
My Feedback: (76)
Join Date: Aug 2004
Location: Baton Rouge, LA
Posts: 2,715
Likes: 0
Received 0 Likes
on
0 Posts
Then you haven't been reading correctly or looking thoroughly as JR/Spektrum crash 10x as much, hence 4 genrations of 2.4 that aren't even backwards compatible (except for 2 and x) I'm sure they'll need a 5th generation in the next couple of years, where as FAAST has been working good from day 1.
04-14-2014, 11:11 AM
#94
Member
Join Date: Dec 2013
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
Has AMA banned any other models in the past? I can think of no surer way to lose our right to fly PERIOD, than for landowners (individuals, municipalities, states...) to know that our supposed insurance might not cover the collateral damage a failure might cause.
04-17-2014, 12:19 PM
#95
Sorry it took so long, I don't have access to photoshop like I used to.
I calculated the pivot point and it appears to be at about 18% of MAC. Which is safe as far as stability is concerned. Make sure you use appropriate servos and set the linkages to get the exact amount of throw you need with no less that 100% of ATV. A pivot this far forward will take more force than a further aft pivot but I would not move it aft! I will try to calculate this again if I can find a better program to measure it with.
EDIT OK I did it with a better technique and got 19%.
I calculated the pivot point and it appears to be at about 18% of MAC. Which is safe as far as stability is concerned. Make sure you use appropriate servos and set the linkages to get the exact amount of throw you need with no less that 100% of ATV. A pivot this far forward will take more force than a further aft pivot but I would not move it aft! I will try to calculate this again if I can find a better program to measure it with.
EDIT OK I did it with a better technique and got 19%.
Last edited by mr_matt; 04-18-2014 at 11:32 AM.
