Eagler's Nest
Airframes => Single Seaters => XL => Topic started by: Flyguyeddy on October 02, 2018, 07:28:26 AM
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I need to make a new seat so i have been trying to guestimate how long it needs to be. This is me sitting on some plywood planks positioned to be pretty low in the back. I am 5’9” tall and my head is firmly in the rear tubing cluster. Doesnt seem like a fun place to be whilst flying without a helmet.
What am i doing wrong here?
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That is the XL right? Man you are scaring me - I am 6'1" and if you do not fight at 5'9", I am going to have some real issues with mine. I do know the standard aluminum mesh seat does sag down a bit but not sure how much. Not many side view pictures out there that I know of with bigger pilots in the XL - anyone?
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Well I can say at 6' 3'' I did make a longer seat, moved the top tube up 2 to 3 inches and extended the wing mounting bracket to make the bottom of the wing flush with the top tube.
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Well I can say at 6' 3'' I did make a longer seat, moved the top tube up 2 to 3 inches and extended the wing mounting bracket to make the bottom of the wing flush with the top tube.
You said you moved the top tube up 2-3" and I think we can visulize what this entailed easy enough.
What do you mean by "extending wing mounting brackets" Are you making this change to the wings or to the frame above the extended top tube? Got photos?
By these things happening, your struts became longer yes? Or did you keep the same angle and move the strut ending location? (this would still make the struts longer)
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Looks like perfect fit to me, its not the chair you sit in to watch the game, maybe lots of foam pipe insulation? however i am 5' 9" also and building the standard eagle, now time to study seat mods.
Peace
Theo
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I believe extending the wing was referring to moving the wing mount attachment bracket. In this case moving them down on the spar which would move the wing up. I have seen this discussed and I believe approved by the "boss".
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I believe extending the wing was referring to moving the wing mount attachment bracket. In this case moving them down on the spar which would move the wing up. I have seen this discussed and I believe approved by the "boss".
While this is probably true, (but who knows) it would seem that a simple explanation done by the person that said they did it, would suffice in this case. One of the biggest problems I see in small aircraft building, is that "a proven way that works" gets interpreted into many variations with SOME of them not working... wasting time for many, and certainly could cause set backs.
We all know that just in cosmetic finish alone we could have 10 identical XL's sitting in a line with huge difference in looks (which is great) but fundamentally in structure they are all done in a correct manner.
Simple statements such as " I thought I could leave out a station, or spread the ribs or use lighter tubing here" leaves far to much to the imagination. For the average builder. in my honest opinion.
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I made the change to the frame above the extended top tube. I have a pic but cannot get it to load on the website. Yes, the struts did become longer. Same angle with longer struts.
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I found this with a search. I would try it.
https://www.eaglersnest.com/forum/index.php?topic=334.msg1877#msg1877
Your final see could look something like this .
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No body has said what's wrong with the plans seat ?????? Leonard
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That doesnt fit either
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Just an observation... My LEXL plans show the short vertical tube between station 2 and 3 to be between 7 and 7-1/2 inches behind station 2. It may be the angle in your photo, but it appears your vertical is farther back, which shortens the area between station 3 and the front seat mounting tube. Wouldn't moving the front seat mounting tube forward give more room for seat sag and allow you to sit lower?
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That is a possibility. If im not mistaken, this may have been a previous builder modification (he was a little bit shorter than me)
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I need to make a new seat so i have been trying to guestimate how long it needs to be. This is me sitting on some plywood planks positioned to be pretty low in the back. I am 5’9” tall and my head is firmly in the rear tubing cluster. Doesnt seem like a fun place to be whilst flying without a helmet.
What am i doing wrong here?
Could you take a measurement or two and report back, my frame work and yours sure don't look the same (thus fit the person, a lot differently)
Most notable difference would be your front over head tube cluster to overhead rear cluster c to C measurement.
I would be interested to know this, and why yours seems to be canted fwd at the top a great deal more.
Scott
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You can see more pictures of my fuselage being built at http://www.jimmylwright.com/ which is the person i bought it from
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(appears different that other plan built frames)
That is a possibility. If im not mistaken, this may have been a previous builder modification (he was a little bit shorter than me)
Ok, until I hear and others hear differently, we can assume your frame, which seems to be too close to your neck and head,(reason for your original post and title) can be considered to be the "same but different" from the plans, maybe... or something like that, sorta.
As a builder, I would sure like to know, if my rear spar attach point was going to connect to the cluster center as intended.
In general, small aircraft have a fairly safe fudge factors, i.e., a station can be ahead or back .125" and things be ok, but never are they (the fudging) intended to be compounding.
I am not saying this has happened, but am saying it has happened for some, where a miscalculation was repeated over and over and thus took the builder into never-never land.
This is one of the reasons that exact drawings for CAD and the like, have a POINT of 0/0. Where every part dimension, is either X" back, above or besides this 0/0 mark. other wise known as X/Y/Z dimensions. Saves a lot of grief down the road.
These dimensions can drawn into almost any set of plans. (C station) equals- A to B + B to C D station equals A to C + C to D as opposed to C is so many inches from B, and D is so many from D as you can see, if an error was made anywhere along the line, it just would get carried to the next, --- then two errors and so on.
It happens all the time.... in houses, land surveys, and airplanes. example, how many times have you heard of a homebuilder, start a stud wall, to 8' then restart his measurement from the end of 8' to the next 8' the third time, he finds he is a full 1.5" off. NOT good!
Scott
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That is a possibility. If im not mistaken, this may have been a previous builder modification (he was a little bit shorter than me)
This is in reference to the previous post about the lower seat crossbar between sta2 and sta3
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This is what i came up with. I do not have my plans handy so i cannot check them. The rear seat back to upper tube dimension may be a little off. I will clamp the frame to a nice flat table and attempt to refine these measurements. All measurements noted are center of tube to center of tube or cluster (as best i can guess on the sta3 cluster)
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In your drawing where the 8-3/8 dimension is circled, the plans show the vertical tube that intersects the cockpit diagonal should be 7-1/4". This would move the seat mounting tube forward of yours. Evidently the previous builder did not want to follow the plans for this area. You might want to place a dummy tube in the correct location and see if it makes enough difference to warrant changing your forward seat mount. It probably won't, but at least mocking up the correct dimensions would show you what's happening in this area.
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Flyguyeddy
I am going to presume your dimensions were fairly close that you placed on the drawing sketch.
in that case
if you followed (or the builder) page 6 of the XL drawings, you will see where the head room went. As it would appear there is 4-5" missing, through a combination of shorter tubes. Compare the top two near vertical tubes and the bottom 2nd station tube going up to windscreen area tube--
I am going to post this photo...for comparison- Don't anyone try to build based on these dimensions, you need the whole set of plans to put these into perspective.
these are end point to end point measurements of the tubes. NOT center plane measurements. But you will see the difference if you measured in the same manner. There is enough difference that one or the other has to be wavered from the plans a fair bit. I have a guess as to which one. But you can compare.
Now before some tell me I am a .250" off here or there, I did a quick overlay of 3-D lines to measure, and might not have right to center of clusters... but am close. I wanted a general check to the numbers posted.
best of success
Scott
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Never heard anymore-- But here is a comparison between the "modified one" (hand written measurements" and one pretty close (red print) to Plans if not exact to plans. I am guessing the second one is darn close because the 2% angle wing attach points were right on the money.
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sorry folks, I see my eyes blurred 22.297 from 20.297 So the rear is only 4+ inches lower, not 6+" Still a fairly large amount when changing head room specs. (as well as the other things that go with it.
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Sorry for the long wait for a response. I need to remeasure things because i have to assume you wanted along the tube measurements not as seen from the side type measurements (unless i am mistaken and my fuselage is WAY off).
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Just make a temporary sling seat out of cloth and use a ply cousin in the bottom, I bet you will fit just fine, I'm making mine now and with the cloth sling and the permanate ply/foam I tested I have more head room than just a sling seat.
Here is the test seat, 17x15 ply to match 17x15x3 foam wrapped with material.