Kinda sorta looking at my finances to see if there's any possibility of building an S-21, and I'm having all kinds of weird ideas on how to save weight. One is to replace the original Rans seats with carbon bucket racing seats. What would you guesstimate the weight of the Rans seats to be? I'm also a bit hesitant about the electric trim. I like mechanical stuff, and I like the manual trim on the S-6, so I'm looking into the possibilities of installing that instead.
The S-21 seats are already very light. They are 1/2 or less the weight of my Cessna 150 seats. Carbon bucket style may be lighter but only by ounces. Certainly not pounds.
Also, it’ll be hard to shed much weight on the S-21. It’s already built very light. Almost to a fault. I’ve had to add some weight with extra structure in areas because I was not comfortable with how delicate it is. The skins are the thinnest I’ve ever seen on an airplane at .020”. If you breath on them wrong they’ll dent. Like I say, this thing is a delicate flower. Very light construction. Ways to save weight without affecting strength would be to eliminate all the plastic closeouts. That would save probably 10-12lb.
The airplane is already built lighter than I would prefer. I wouldn’t worry about weight if I were you, you wouldn’t notice the difference between flying the 21 with 30 pounds of gear in the back.
@@Outbound300 I should clarify. I`d be flying it within the LSA class here in Norway. I am comparing to other LSA`s and not other experimentals. I am not suggesting touching the structure either. What I`d want is a very low weight, to allow for more fuel/pax/payload but under 1320lbs/600kg. The new regulations states that you are allowed to fly an LSA on top, if it got a parachute. It`s probably down to preference, but I`d want an Edge Performance engine (they´re norwegian, support is infinetely better than Lycontitans, and weighs the same as Rotaxes), Kanardia instruments (European, there`s a local daler and good experienses in other EU LSA`s. Their EFIS weighs about 1/2 that of Garmin or similar). E-props are super light and goes well with EP engines, the four blade one is very quiet too. All this would save quite a bit of weight, especially if I also went for the carbon bits when thats an option offered by Rans. Economically, it`d still be cheaper than a typical experimental build. Probably because the brands that offers all these low weight options are european. The seat thing was more of a brain fart… Like snipping of the tag on your jacket to save weight when hikinh. I have just wondered why so many aircraft seats looks like padded dining chairs, when carbon bucket seats are both lighter and more comfortable. Might depend on the average body shape though… And price.
I would love it if someone came up with an adjustable lockable sliding seat track solution like from a Cessna 150. 350 hours sitting in a S21’s seat and I’m still not a fan of the mechanism.
Well, for starters in the Taildragger configuration on the ground, it’s harder to scoop the seat up. Not the biggest deal, but my main issue is they are so many adjustment notches that it’s hard to find your original position in flight if you move your seat back for long cross country’s like I do. Also, the seat doesn’t fit perfectly fixed in the track. It has a little slope or can twist slightly which puts the rear locking pins out of alignment by one notch and the seat back won’t go as far back. If I could make adjustable stops forward and aft where I like the seat for takeoff and normal flying and then for cruise. Plus, making the seat to stay square in the track I’d be much happier with it.
Interesting. About the seats not being square on tracks. During assembly of seat tracks to frame its critical that the two notched tracks are perfectly aligned. If one track is even so much as .090” forward or aft of the other it can cause a ‘racking’ or out of square condition. Mine are dead nuts aligned and the seats lock in perfectly on both sides with almost zero play. Yours is factory built? You may want to see how aligned the tracks are with one another. Maybe they were sloppy at the factory that day? Fixed locks for forward and aft positions is a great idea. Easy to engineer up some parts for that. I’ll consider that.
@@Outbound300 I would be very interested if you came up with a solution for fixed locks. I guess what I was trying to convey with the seat tracks are that the plastic L brackets that go on the bottom of the seats don’t allow for a perfectly tight fit therefore the seat can sort of wiggle on the tracks. I do believe my tracks are properly aligned. That being said, if the seat twists a degree it can put the right track pin one notch forward than the left pin binding up and not allowing the rear seat going back all the way. Plus it probably puts a lot more load on the pin most forward. If I had four of those plastic/nylon L brackets with tighter tolerances, that would probably alleviate the seat from slightly twisting left and right when sliding it. I hear Randy is looking into re-designing with a roller system instead of the nylon L brackets. Same ratchet and track adjustment system. We shall see.
Most kit aircraft (and some production ones) have what I consider pretty flimsy seats. Seats should be at the very least, be designed to 7G ultimate or so. A big human is about the same weight as an engine and would you consider that seat structure strong enough to support an engine at 7G? I like Rans kits and maybe they actually tested some of these to failure, but they still look a bit fragile. A 250lbs person at 7G=1750lbs. Plus the seat back will probably start cracking just outside those nice hinge brackets in no time. No matter how often you tell people, they will always shove back hard on the back while adjusting themselves (or their underwear!) and this puts enormous stress on that point. Time will tell...
I can’t argue with this logic. That said this seat design has been used in many previous Rans aircraft that have been flying (and presumably crashing) for decades. I haven’t heard of a mention of the seats being a systemic problem. Worst case these could be easily fabricated from steel tube and welded gussets similar to Cessna 150 seats.
![เจ็บที่ยังฮัก - ม่อน วรวิทย์ [ Official Mv ] จอนนี่มิวสิค](http://i.ytimg.com/vi/KALIGSRSjFs/mqdefault.jpg)
Thanks for the tip on how to put the seat back cushion on. I read and reread every step. Looks like an update is needed.
thanks for pointing out the instruction sequence error.
Nice Job!
Kinda sorta looking at my finances to see if there's any possibility of building an S-21, and I'm having all kinds of weird ideas on how to save weight. One is to replace the original Rans seats with carbon bucket racing seats. What would you guesstimate the weight of the Rans seats to be? I'm also a bit hesitant about the electric trim. I like mechanical stuff, and I like the manual trim on the S-6, so I'm looking into the possibilities of installing that instead.
The S-21 seats are already very light. They are 1/2 or less the weight of my Cessna 150 seats. Carbon bucket style may be lighter but only by ounces. Certainly not pounds.
Also, it’ll be hard to shed much weight on the S-21. It’s already built very light. Almost to a fault. I’ve had to add some weight with extra structure in areas because I was not comfortable with how delicate it is.
The skins are the thinnest I’ve ever seen on an airplane at .020”. If you breath on them wrong they’ll dent.
Like I say, this thing is a delicate flower. Very light construction.
Ways to save weight without affecting strength would be to eliminate all the plastic closeouts. That would save probably 10-12lb.
The airplane is already built lighter than I would prefer. I wouldn’t worry about weight if I were you, you wouldn’t notice the difference between flying the 21 with 30 pounds of gear in the back.
@@Outbound300 I should clarify. I`d be flying it within the LSA class here in Norway. I am comparing to other LSA`s and not other experimentals. I am not suggesting touching the structure either. What I`d want is a very low weight, to allow for more fuel/pax/payload but under 1320lbs/600kg. The new regulations states that you are allowed to fly an LSA on top, if it got a parachute.
It`s probably down to preference, but I`d want an Edge Performance engine (they´re norwegian, support is infinetely better than Lycontitans, and weighs the same as Rotaxes), Kanardia instruments (European, there`s a local daler and good experienses in other EU LSA`s. Their EFIS weighs about 1/2 that of Garmin or similar). E-props are super light and goes well with EP engines, the four blade one is very quiet too. All this would save quite a bit of weight, especially if I also went for the carbon bits when thats an option offered by Rans. Economically, it`d still be cheaper than a typical experimental build. Probably because the brands that offers all these low weight options are european.
The seat thing was more of a brain fart… Like snipping of the tag on your jacket to save weight when hikinh. I have just wondered why so many aircraft seats looks like padded dining chairs, when carbon bucket seats are both lighter and more comfortable. Might depend on the average body shape though… And price.
I would love it if someone came up with an adjustable lockable sliding seat track solution like from a Cessna 150. 350 hours sitting in a S21’s seat and I’m still not a fan of the mechanism.
What specifically about the Rans seat mechanism do you not like? I have no practical experience with the seats yet but definitely curious.
Well, for starters in the Taildragger configuration on the ground, it’s harder to scoop the seat up. Not the biggest deal, but my main issue is they are so many adjustment notches that it’s hard to find your original position in flight if you move your seat back for long cross country’s like I do. Also, the seat doesn’t fit perfectly fixed in the track. It has a little slope or can twist slightly which puts the rear locking pins out of alignment by one notch and the seat back won’t go as far back. If I could make adjustable stops forward and aft where I like the seat for takeoff and normal flying and then for cruise. Plus, making the seat to stay square in the track I’d be much happier with it.
Interesting. About the seats not being square on tracks. During assembly of seat tracks to frame its critical that the two notched tracks are perfectly aligned. If one track is even so much as .090” forward or aft of the other it can cause a ‘racking’ or out of square condition. Mine are dead nuts aligned and the seats lock in perfectly on both sides with almost zero play.
Yours is factory built? You may want to see how aligned the tracks are with one another. Maybe they were sloppy at the factory that day?
Fixed locks for forward and aft positions is a great idea. Easy to engineer up some parts for that. I’ll consider that.
@@Outbound300 I would be very interested if you came up with a solution for fixed locks. I guess what I was trying to convey with the seat tracks are that the plastic L brackets that go on the bottom of the seats don’t allow for a perfectly tight fit therefore the seat can sort of wiggle on the tracks. I do believe my tracks are properly aligned. That being said, if the seat twists a degree it can put the right track pin one notch forward than the left pin binding up and not allowing the rear seat going back all the way. Plus it probably puts a lot more load on the pin most forward. If I had four of those plastic/nylon L brackets with tighter tolerances, that would probably alleviate the seat from slightly twisting left and right when sliding it. I hear Randy is looking into re-designing with a roller system instead of the nylon L brackets. Same ratchet and track adjustment system. We shall see.
Most kit aircraft (and some production ones) have what I consider pretty flimsy seats. Seats should be at the very least, be designed to 7G ultimate or so. A big human is about the same weight as an engine and would you consider that seat structure strong enough to support an engine at 7G? I like Rans kits and maybe they actually tested some of these to failure, but they still look a bit fragile. A 250lbs person at 7G=1750lbs. Plus the seat back will probably start cracking just outside those nice hinge brackets in no time. No matter how often you tell people, they will always shove back hard on the back while adjusting themselves (or their underwear!) and this puts enormous stress on that point. Time will tell...
I can’t argue with this logic. That said this seat design has been used in many previous Rans aircraft that have been flying (and presumably crashing) for decades. I haven’t heard of a mention of the seats being a systemic problem.
Worst case these could be easily fabricated from steel tube and welded gussets similar to Cessna 150 seats.