Converting 2-seater to 4-seater?

Fellow_Pilot

Fellow_Pilot

Pre-Flight
Joined
May 12, 2017
Messages
44
Display Name
Display name:
Fellow_Pilot
How hard would it be to convert a two seater lsa to a four seater, out of curiosity? Becuase we shouldn't pay an extra $30000 to get two extra seats.
 
Well, should be able to just get the sawzaw out, cut the plane in half, and stick in a few more seats with a little duct tape...
 
I would think impossible unless it was built E-AB to begin with. Otherwise it would have to be re-certified under some category other than S-LSA/E-LSA and that would seem to be difficult at best.
 
Turn an LSA into a four-place? Good luck with that. They barely have enough juice for two people.
 
Maybe not even an lsa. Just any plane that is sold in that price range.
 
pzv5j7l.jpg
 
I don't know of any. Typically folks go the opposite direction and make a 4-seater into a 2-seater (by simply removing seats--I can do this in about a minute in my own plane), or it's sold as a 4-seater and it's really a good 2-seater like a 172. Best to just go get something designed for what you want from the get go vs trying to mod something which, if possible, would most likely be expensive and time consuming.
 
If you buy used, there are a ton of choices of 4 seaters in a new LSA's price range. New, any legal four seater is gonna cost you.
 
Depends on what you are starting with.
You have to probably stretch the fuselage just a tad. Gross weight is going to go up so you would re-design the structures such as wing spars and landing gear.
Speeds? If you want to keep near the same stall speeds a bit more span would be in order - no big deal since you are already re-engineering the structure.

Starting by modifying a design would be not such a huge deal.
Trying to modify an already done been made airplane would be a whole nudder can of worms.
 
If you look at the difference of a 152 and a 172 you’ll see an example of what would be about the simplest redesign to move from 2 to 4 seats. I think. Perhaps. Well for sure on fridays. Might not be true any other day if the week.
 
I think Jabiru used to market an LSA in the US as a 2 seater that is a 4 seater in other countries. You couldn't fly it here legally though.
 
It's just that awkward situation where you usually have a two seater but there might be that one day where an extra two people come along. I mean sure you could rent, but why when you already have a plane?
 
Fellow_Pilot said:
It's just that awkward situation where you usually have a two seater but there might be that one day where an extra two people come along. I mean sure you could rent, but why when you already have a plane?
Click to expand...

This happens all the time. Look realistically at your mission--don't get suckered into buying an airplane for 10% of your mission.
 
It’s not as simple as just ‘adding two extra seats’. That wouldn’t solve your problem.
 
Fellow_Pilot said:
It's just that awkward situation where you usually have a two seater but there might be that one day where an extra two people come along. I mean sure you could rent, but why when you already have a plane?
Click to expand...
Oh, if that's all you want...
Get an O-320 Luscombe and have them squeeze in the baggage area.
 
Capt. Geoffrey Thorpe said:
Oh, if that's all you want...
Get an O-320 Luscombe and have them squeeze in the baggage area.
Click to expand...
lol I guess something like that. Just put seats in the baggage area and split the connection to the headsets, put some windows, O-320, and problem solved!
 
The jabiru,is a four seater in Australia not sure it has the performanceto lift four people and fuel.why even use seats,just have them sit on the floor of the baggage compartment in a jab.
 
Would be nice if there could be a similar priced four seater that when there is nobody in the back, have the seats folded/taken out and used as extended baggage space.
 
mscard88 said:
Just have to stretch it a little....
Click to expand...

I'm sure we'll order a ton of those monstrosities!

Just flew a MAX-8 the other day and wandered around the cabin before we boarded. Two more rows in four extra feet of tube. Let's just say I'm happy to be up front, and for someone to *prefer* to be on a 737 flight deck - that's saying something!
 
The only plane I know of that did it inexpensively is when they stretched the Glasstar into the Sportsman 2+2.
 
Fellow_Pilot said:
How hard would it be to convert a two seater lsa to a four seater, out of curiosity? Becuase we shouldn't pay an extra $30000 to get two extra seats.
Click to expand...

You gotta whole lotta interrelated things going on there.

Two more seats means more weight. More weight means more wing area to maintain wing loading, which adds more weight. More weight means more engine to maintain power loading, climb and cruise performance. A bigger motor means more fuel capacity is needed. More fuel means more weight. I'm sure you see where this is heading.;)

The "L" in LSA stands for "Light". Suggest you keep it that way.
 
kayoh190 said:
I'm sure we'll order a ton of those monstrosities!

Just flew a MAX-8 the other day and wandered around the cabin before we boarded. Two more rows in four extra feet of tube. Let's just say I'm happy to be up front, and for someone to *prefer* to be on a 737 flight deck - that's saying something!
Click to expand...

I WILL TYPE LOUDER SO YOU CAN HEAR!

Bob
 
Fellow_Pilot said:
How hard would it be to convert a two seater lsa to a four seater, out of curiosity? Becuase we shouldn't pay an extra $30000 to get two extra seats.
Click to expand...

The short answer is ‘hard’. A friend of mine took an Alarus CH2000 certified aircraft and started the process on converting it to a Zenair CH640. After a bout a year he realized it wasn’t worth the effort.
 
Fellow_Pilot said:
How hard would it be to convert a two seater lsa to a four seater, out of curiosity? Becuase we shouldn't pay an extra $30000 to get two extra seats.
Click to expand...

LSA aircraft are limited to 2 seats. Your bigger problem would be fitting 4 people into a 400# useful load airplane.
 
Also, don’t forget about the Sling 4. 1,100 pound empty weight with a 115 HP 914 turbo. If sure flew like an LSA with great useful load too. Granted it’s not an LSA and has a constant speed prop.
 
Andrew Morris said:
Also, don’t forget about the Sling 4. 1,100 pound empty weight with a 115 HP 914 turbo. If sure flew like an LSA with great useful load too. Granted it’s not an LSA and has a constant speed prop.
Click to expand...

The OP said he had a $30K target. Kinda puts the Sling and pretty much any S-LSA and probably most E-LSAs out of reach.
 
tsts4 said:
The OP said he had a $30K target. Kinda puts the Sling and pretty much any S-LSA and probably most E-LSAs out of reach.
Click to expand...

I thought he was objecting to spending an additional 30K for just two additional seats while ignoring the longer fuselage, bigger wing, higher HP engine, etc. that usually come with it.
 
SkyDog58 said:
I thought he was objecting to spending an additional 30K for just two additional seats while ignoring the longer fuselage, bigger wing, higher HP engine, etc. that usually come with it.
Click to expand...

You're right -- my bad.
 
Even $30K won't change the Laws of Physics.
 
The BD-4 is a 2+2. Really a 2 place plane with enough room for two seats in the back. Not like a 182, but you can toss the kids or a couple of dogs back there. I've read the book, and looked over the plans... actually looks really easy to put together. Fast for its power as well. It was on my short list until the CGS showed up... and the wife insisted on a ready-to-fly four seater.
1200px-Raffensparger_BD-4_%28N643R%29.jpg
 
Fellow_Pilot said:
Would be nice if there could be a similar priced four seater that when there is nobody in the back, have the seats folded/taken out and used as extended baggage space.
Click to expand...
You can easily take the rear seats out of a Piper Cherokee for more baggage room. It is a four seater but you still have to be careful not to overload it beyond it's weight limit if you put four people in. Four 200 pounders with full 50 gals of fuel is foolish. With any plane you still have to live within the weight and balance specs.
 
2023 Sling 2 - 912 ULS has a Maximum Useful Load of 696 lbs (316 Kg). I weigh 150 lb, my wife weighs 165 lb and my two kids are each 80 lbs each, all four of us totaling at about 475 lbs. If I add 35 lbs for two extra seats and 5 lbs for two extra headsets, leading my total weight to 515 lbs (say 525 lbs), I am still left with about 170 lbs of usable weight, I am sure the cockpit has sufficient room for all four of us as we are not at all too tall. I can still consider installing ballistic parachute (Magnum is about 40 lbs), however, not sure if that would leave me with sufficient room for 2 extra seats, but it might as well. So, my question is, why can't this be done? I don't intend to haul any cargo or just minimal cargo.

One issue I can think of might be Center of Gravity shifting backwards as I add more weight in the rear, but at the same time I am brining the front seats forward shifting the COG forward. But again, the rear is also designed for some cargo, so overall it should work out physics-wise.

The only issue I can think of, as already mentioned above, is getting the air worthiness certificate from FAA. Is this the only issue or there is more to that? FAA allows you building your own aircraft from the scratch and apply for FAA certification.
 
Jitendra Pandey said:
The only issue I can think of, as already mentioned above, is getting the air worthiness certificate from FAA. Is this the only issue or there is more to that? FAA allows you building your own aircraft from the scratch and apply for FAA certification.
Click to expand...
If you start with a kit and build it under the Experimental Amateur Built rules (meet the so called 51% rule), not a problem. If you start with a factory built aircraft you are basicly out of luck.

Warning: This is my video and I will get a fraction of a penny if you watch it. So it's best that that you don't click on it. Plus, it's boring.

 
Jitendra Pandey said:
2023 Sling 2 - 912 ULS has a Maximum Useful Load of 696 lbs (316 Kg). I weigh 150 lb, my wife weighs 165 lb and my two kids are each 80 lbs each, all four of us totaling at about 475 lbs. If I add 35 lbs for two extra seats and 5 lbs for two extra headsets, leading my total weight to 515 lbs (say 525 lbs), I am still left with about 170 lbs of usable weight, I am sure the cockpit has sufficient room for all four of us as we are not at all too tall. I can still consider installing ballistic parachute (Magnum is about 40 lbs), however, not sure if that would leave me with sufficient room for 2 extra seats, but it might as well. So, my question is, why can't this be done? I don't intend to haul any cargo or just minimal cargo.

One issue I can think of might be Center of Gravity shifting backwards as I add more weight in the rear, but at the same time I am brining the front seats forward shifting the COG forward. But again, the rear is also designed for some cargo, so overall it should work out physics-wise.

The only issue I can think of, as already mentioned above, is getting the air worthiness certificate from FAA. Is this the only issue or there is more to that? FAA allows you building your own aircraft from the scratch and apply for FAA certification.
Click to expand...

Room is only part of it. Does the airframe structure support adding seats and restraints? Way simpler to go with a 4-place design from the get-go instead of trying to make 2 seater into a 4 seater. Also you didn't include fuel load in your useful load equation.
 
You must log in or register to reply here.
Back
Top