Backcountry Pilot • How much weight can be shaved off the Rans S-21?

How much weight can be shaved off the Rans S-21?

Sometimes the most fun way to get into the backcountry, Part 103 Ultralights and Light Sport Aircraft have their own considerations.
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How much weight can be shaved off the Rans S-21?

My mission is shorter trips in the sidecountry, and just for fun. I have friends living about an hours flight away, and there are a lot of nice places to go hiking, surfing og skiing. I'd like to be able to bring a lot of stuff with me. Not necessarily heavy, but volunimous stuff like a bodyboard, wetsuit, ski boots, sleeping bag, tent and maybe my dog. Nothing rougher than grass strips, and nothing shorter than about 1000 feet. There's a lot of forest and mountains, but most of the time I'll be flying in areas where you can see sivilization.

I live in Norway, and the most common plane for this sort of mission is the ICP Savannah S. I like it, but there's not quite as spacious as I'd like. It won't be disastrous to leave the dog or some other of the biggest stuff at home, but I'd like to explore the S-21 a little bit as it seem to fit the bill a little bit better. Today I'm flying my clubs Aeroprakt A32. It's brilliant, but also not quite as spacious as I'd like. It also isn't avaliable as a kit, and costs a bit much.

The basic weight of the S-21 is 820, would it be possible to push it down to 790 and what would it take? The carbon package saves about 14 lbs on the S-20, so I assume it's the same for the S-20. Engine wise it seems the 912 ULS is the best option, but the UL260 is a bit tempting. The Rotax is very well known, though. That will count for a lot. I suppose some weight can be saved getting a bit smaller tires. Something like 18 or 21x800x6. But then there's really just the paintjob, upholstery and the instrumentation.

For my mission I think maybe a very basic set of steamgauges and an ipad would do just the trick, but I don't know how much that would save. And then I'd have to come up with upholstery that somehow is lighter than what people who are actually experts on aircraft has designed...

The reason to bring it down to weight is to have it approved as an LSA in Norway. There's to "hard rule" on MTOW, but if it's too far north of 350/360kg (770-790 lbs) the authorities will be sceptical. I think the rule it has to have a "plausible" payload. I.e. two people, their lunch and enough fuel for an hour, and be below 1320.

I also don't want to bother Randy with this, since I've pestered him enough without yet being ready to actually buy something. His time is precious, so I'd rather ask here where you guys who might even think having a go at my question might be considered fun.
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Re: How much weight can be shaved off the Rans S-21?

Doubtful you could save much weight, as factory (ANY factory, not a dig at RANS) listed empty weights are notoriously "optimistic." NO paint would be the easiest, and cost the least. NO steam gauges, just a light MFD is all you need nowadays. For sure not the Lyc engine.
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Re: How much weight can be shaved off the Rans S-21?

Yes, the S-21 has space, but I doubt you'll get it under 800 pounds.

But, what about the S-20? It has side by side seating and a fairly large baggage area. And, I think you'd have a much better chance of keeping the weight down with it and a Rotax.

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Re: How much weight can be shaved off the Rans S-21?

Ditch the steam gauges for sure, just go with an iPad. You can buy all the probes you need that will hook up to it. That Andale a AV30 for attitude, A/S, ALT. But not sure you'd get it down under 800, I agree with Courierguy that most manufacturers are optimistic on their EW.
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Re: How much weight can be shaved off the Rans S-21?

There's the option of hanging this thing on the nose: https://d-motor-usa.com/index.php/lf26/specifications/

But it's hard to find any definite experiences with the D-Motor so far. Judging by the specifications alone, I'd say that apart from probably not being the most efficient engine out there, it's very well set up for reliability. But 91hp?... That's a little bit low. It's probably enough to get the S-21 airborne, but it might be a total waste of potential. And then ofcourse such a lightweight engine might throw the balance off.

In my club, there's people who's flying with just iPad screens, and it's worked flawlessly. But being the guinea pig for something as pricey as and important as an engine? I dunno.

Oh well... 800 lbs doesn't sound too bad. Maybe that's low enough to be worth contacting the authorities and just ask them. There's atleast one Murphy Rebel flying here in Norway. When he weighed it, he put the smallest tires he could find on it. The guy from the norwegian Aviation Administration just gave him a look and gave it the green light...
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Re: How much weight can be shaved off the Rans S-21?

mtv wrote:Yes, the S-21 has space, but I doubt you'll get it under 800 pounds.

But, what about the S-20? It has side by side seating and a fairly large baggage area. And, I think you'd have a much better chance of keeping the weight down with it and a Rotax.

MTV

Build it with Oratex and save paint weight.
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Re: How much weight can be shaved off the Rans S-21?

StuBob wrote:
mtv wrote:Yes, the S-21 has space, but I doubt you'll get it under 800 pounds.

But, what about the S-20? It has side by side seating and a fairly large baggage area. And, I think you'd have a much better chance of keeping the weight down with it and a Rotax.

MTV

Build it with Oratex and save paint weight.


Yes, Oratax is a huge weight savings. If you go with the S-21 then no paint at all.

"Sweat the ounces and the pounds take care of themselves". Weigh EVERYTHING before it goes on the plane.

I'm building a Kitfox and everything has to buy it way on to the plane in terms of weight. I will be under your target weight even with a 7 cylinder radial engine.

I know it's not possible any more but people used to land on grass with 6.00x6 tires and live to tell about it. Fixed pitch prop for sure, either wood or lightweight composite. Steam gauges are heavier than a small EFIS. EarthX battery, no auto pilot, single COM with a built in intercom, LED tip strobes/position lights (no light in the tail). No carpet, simple upholstery. Beringer brakes/wheels would save about 4 pounds (and lighten my wallet about the same, but all brake/wheel sets cost big money). Simple bungee or die-spring cabane type gear are lighter than spring gear.

I'm sticking with full dual controls but it is a significant weight savings to ditch one set of rudder pedals/brake master cylinders. My airplane project came with two sets of lift struts and two sets of tail plane struts (modern aero shape and original oval/round tubes). I sold my original oval shape wing lift struts early on and didn't realize until later how much heavier the aero shaped ones are. When it came to the tail plane struts (fuselage to underside of horizontal stab), the old round tube ones were half as heavy (over a pound right there).
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Re: How much weight can be shaved off the Rans S-21?

StuBob wrote:
mtv wrote:Yes, the S-21 has space, but I doubt you'll get it under 800 pounds.

But, what about the S-20? It has side by side seating and a fairly large baggage area. And, I think you'd have a much better chance of keeping the weight down with it and a Rotax.

MTV

Build it with Oratex and save paint weight.


And, that kit is going to be a lot cheaper to ship to Europe, btw.

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Re: How much weight can be shaved off the Rans S-21?

aftCG wrote:
StuBob wrote:
mtv wrote:Yes, the S-21 has space, but I doubt you'll get it under 800 pounds.

But, what about the S-20? It has side by side seating and a fairly large baggage area. And, I think you'd have a much better chance of keeping the weight down with it and a Rotax.

MTV

Build it with Oratex and save paint weight.


Yes, Oratax is a huge weight savings. If you go with the S-21 then no paint at all.

"Sweat the ounces and the pounds take care of themselves". Weigh EVERYTHING before it goes on the plane.

I'm building a Kitfox and everything has to buy it way on to the plane in terms of weight. I will be under your target weight even with a 7 cylinder radial engine.

I know it's not possible any more but people used to land on grass with 6.00x6 tires and live to tell about it. Fixed pitch prop for sure, either wood or lightweight composite. Steam gauges are heavier than a small EFIS. EarthX battery, no auto pilot, single COM with a built in intercom, LED tip strobes/position lights (no light in the tail). No carpet, simple upholstery. Beringer brakes/wheels would save about 4 pounds (and lighten my wallet about the same, but all brake/wheel sets cost big money). Simple bungee or die-spring cabane type gear are lighter than spring gear.

I'm sticking with full dual controls but it is a significant weight savings to ditch one set of rudder pedals/brake master cylinders. My airplane project came with two sets of lift struts and two sets of tail plane struts (modern aero shape and original oval/round tubes). I sold my original oval shape wing lift struts early on and didn't realize until later how much heavier the aero shaped ones are. When it came to the tail plane struts (fuselage to underside of horizontal stab), the old round tube ones were half as heavy (over a pound right there).


I'm sure 6.00x6 would do just fine in the sidecountry! People fly in and out of 1000-1800 grass strips alle the time here, with everything from RV's to Cubs. Big, fat tires would be just for the looks in my case.

I have been trying to find out, how much weight there is to be saved from going from a six pack and basic engine monitoring gauges, and to something like an iPad EFIS all-in-one solution. I thought that just maybe an analogue ASI would be nice as a backup. If I remember correctly, Trent Palmers old setup was an ipad with an ASI hidden behind it. If anything happened, he'd pop out the iPad and use the ASI to get home.

I'm sure the S-20 would fit my bill better, I just need to get over the idea that rag and tube is a bit dated. The safe option would still be the Savanna, since it is so well known in Norway, and we've got a dealer.
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Re: How much weight can be shaved off the Rans S-21?

Varanger wrote:I'm sure 6.00x6 would do just fine in the sidecountry! People fly in and out of 1000-1800 grass strips alle the time here, with everything from RV's to Cubs. Big, fat tires would be just for the looks in my case.

I have been trying to find out, how much weight there is to be saved from going from a six pack and basic engine monitoring gauges, and to something like an iPad EFIS all-in-one solution. I thought that just maybe an analogue ASI would be nice as a backup. If I remember correctly, Trent Palmers old setup was an ipad with an ASI hidden behind it. If anything happened, he'd pop out the iPad and use the ASI to get home.

I'm sure the S-20 would fit my bill better, I just need to get over the idea that rag and tube is a bit dated. The safe option would still be the Savanna, since it is so well known in Norway, and we've got a dealer.


Big tires are extremely heavy (look them up). The difference between a 760 and 800 lb plane is right there in that decision. The biggest bang for the buck is a set of Desser 8.50x6 tires (they weigh the same as a normal 7.00x6 tire). Anything bigger and the weigh goes parabolic and so does the cost.

As for rag and tube I have had the same internal debate. Over time I have come to the conclusion that it may not be as sexy as a composite plane it is less susceptible to daily use damage (runway FOD, hangar rash, hail storms) and far easier to repair. Add to that, a well designed 4130 cage is the place to be in a crash. Think of it as having the ability to reskin your plane in 20 years and compare that to what it would be like on an aluminum or composite plane.

I like Foreflight but I'm one of the many who don't care for apple products. I certainly won't have them be my soul source of information while flying around. I've seen the backup gauges behind and it is clever, but ASI would not be my first choice of what hides behind there (known pitch and power settings make indicated airspeed redundant) . Oil pressure for sure, and maybe altimeter.
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Re: How much weight can be shaved off the Rans S-21?

aftCG wrote:
Varanger wrote:I'm sure 6.00x6 would do just fine in the sidecountry! People fly in and out of 1000-1800 grass strips alle the time here, with everything from RV's to Cubs. Big, fat tires would be just for the looks in my case.

I have been trying to find out, how much weight there is to be saved from going from a six pack and basic engine monitoring gauges, and to something like an iPad EFIS all-in-one solution. I thought that just maybe an analogue ASI would be nice as a backup. If I remember correctly, Trent Palmers old setup was an ipad with an ASI hidden behind it. If anything happened, he'd pop out the iPad and use the ASI to get home.

I'm sure the S-20 would fit my bill better, I just need to get over the idea that rag and tube is a bit dated. The safe option would still be the Savanna, since it is so well known in Norway, and we've got a dealer.


Big tires are extremely heavy (look them up). The difference between a 760 and 800 lb plane is right there in that decision. The biggest bang for the buck is a set of Desser 8.50x6 tires (they weigh the same as a normal 7.00x6 tire). Anything bigger and the weigh goes parabolic and so does the cost.

As for rag and tube I have had the same internal debate. Over time I have come to the conclusion that it may not be as sexy as a composite plane it is less susceptible to daily use damage (runway FOD, hangar rash, hail storms) and far easier to repair. Add to that, a well designed 4130 cage is the place to be in a crash. Think of it as having the ability to reskin your plane in 20 years and compare that to what it would be like on an aluminum or composite plane.

I like Foreflight but I'm one of the many who don't care for apple products. I certainly won't have them be my soul source of information while flying around. I've seen the backup gauges behind and it is clever, but ASI would not be my first choice of what hides behind there (known pitch and power settings make indicated airspeed redundant) . Oil pressure for sure, and maybe altimeter.


Install one uAvionix AV-30 C EX. That gives you a full six pack. Then, whatever engine instruments, and a small GPS for nav......done. The AV-30 is incredibly light weight.

But, I've looked at the Rans S-20, and it is a really roomy airplane, especially compared to ANY of the tandom seat small planes.

MTV

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Re: How much weight can be shaved off the Rans S-21?

The S-20 is really nice, and it looks like Rans might offer Roberts gear for it soon too! Not that I think I really need on the runways and strips I'd be operating off.

Rans used to offer the S-20 with the 141 metal wing, but are not anymore. They haven't said anything about why, but I suppose the S-20 then got too close to the S-21. But for those who the S-21 isn't an option, what would stop anyone from buyng the S-20 fuselage and the 141 wing separate? Would Randy not sell an S-20 sans wings?
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Re: How much weight can be shaved off the Rans S-21?

Rans is not going to offer "Robert's" gear, only John Robert can do that :shock: They appear to be working on a similar cub type gear. If you don't need it, don't get it, as it's heavier (maybe) and draggier (for sure). But IF you need it, get it, as that general type of gear is the best for off airport Unfaired, I'd guesstimate a 10 to 15 mph speed hit over the spring gear. A big deal for the speed freaks, a non issue for those more concerned with off airport stuff. But I don't see the 21 as a "bush plane" myself, now if they came out with an extended wing version, combined with the cub style gear, that would be a different matter. It would further complicate things production wise for them, but how about a "go fast" version, and a "bush" version? Don't hold your breath, they seem to selling like hotcakes as is, and is a good compromise between speed and STOL as is. ANYTHING to make it more bushy (new term) will hurt the speed.
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Re: How much weight can be shaved off the Rans S-21?

The 912 - powered S20 we helped build is 736# on 8.50 Dessers and spring gear and it by no means has a stripped down panel. I don’t like it because it’s very hard to see out of compared to the S7S and I don’t like to fly lying on my back but it does perform very well. You might look closer at the S20 to make weight if you’re wanting SXS seating. There’s one up around Palmer AK that is partially built for sale. I hear the workmanship is excellent. I don’t think there is any appeal to the S21 without the big motor, which blows your empty weight right out of the water.
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Re: How much weight can be shaved off the Rans S-21?

courierguy said it spot on. I've been to the factory twice, flown in the S21 and really liked the plane but if I were looking towards any type of STOL flying, I'd go with the S7, but then it's tandem seating.

I realize you are shying away from a fabric aircraft, but owning both, metal and fabric, they each have their pros and cons. Biggest isdue with metal is rocks, they get slung up and put dents in metal whereas they generally just bounce off a fabric covered plane.

Also, the above comment on the seating position is another consideration I personally wasn't sure of. Something else to look at before making a decision. Actually, I probably wouldn't have thought of it much if an S-20 owner hadn't told me about it beforehand. Mainly affects a passenger as they can't really put their feet flat on the floor.

I realize you're most interested in the latest and greatest flavor of the month (S-21). Have you looked at the Murphy that is there? With the 912 in one, it should make you weight limit. The Rebel is very volumous! Should have problem with room for the gear you mentioned. One of the very few planes that has lots of room and can fit into the Light Sport type configuration when built as such. Good performer with the 912 also.
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Re: How much weight can be shaved off the Rans S-21?

Was w/ Tony at TK1 this past weekend. Randy testing his gear (all bolt on) for the S-20. Gonna happen. Great quality and his shocks rock
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Re: How much weight can be shaved off the Rans S-21?

The 20 or the 21 do not have poor viz by any definition, except by long time S-7 fliers! It has the best of anything I've sat in, very handy when landing in a new to you area.
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Re: How much weight can be shaved off the Rans S-21?

Personally, I think pursuing trying to get the S-21 to fit that "mold" is going to be risky.....kind of like trying to make a square peg fit in a round hole.

I've owned and worked both fabric covered and metal covered airplanes over the years, and to me, the task really decides which is best. And, with this size aircraft, fabric makes MUCH more sense, frankly.

As others have noted, cover it with Oratex fabric and you don't have to paint it, which both adds weight and is a really big deal, labor wise.

Keep the panel simple, which should be easy in this category and for your mission. If you don't intend to fly at night, leave the lights off it. All you'd want them for is recognition and collision avoidance. May not be a big issue where you'll fly.

As others have noted, fabric is very easy to repair, and easy to make it look nice after.....Not so much with metal. But, I've owned fabric planes, operated in a good bit of off airport that have gone for quite some time without needing any repairs. That fabric is a lot tougher than most folks think.

It also seems to me that the Rotax engines are absolutely your best choice, based on the weights you have to make. Well known engines, pretty much bomb proof, and they're light.

And, as I noted earlier, the difference in shipping cost is likely to be pretty big between the 20 and the 21.

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Re: How much weight can be shaved off the Rans S-21?

courierguy wrote:The 20 or the 21 do not have poor viz by any definition, except by long time S-7 fliers! It has the best of anything I've sat in, very handy when landing in a new to you area.
Only high wing I’ve ever flown that you can’t see the main on the side you’re seated on. Maybe there are clear doors now, I don’t know. I can see better out of a Cessna 185 than I can the SXS Rans.
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Re: How much weight can be shaved off the Rans S-21?

You guys are all dead on about everything.

My mission does not require a bush plane, and I know it. I have no use for Roberts gear or similar. I wan't decent short field capabilities to reliably get in and out of 7-900' grass strips (More often the latter than the former), but I never have to land. I don't live or work in a way where I depend on flying to get me around. So I can and will always have plan B if it doesn't feel right. Norway has almost no real backcountry you can fly into, it isn't legal, but a lot of sidecountry. Putting anything bigger than 850s on an LSA in Norway is nothing but styling.

The S-21 has appeal as the latest and greatest, but I think the space and a good cruise speed combined with short field capabilities that are good enough also has its pull on me. But I realise that trying to make it fit in the Norwegian LSA category isn't doable. The S-20 with the 141 wing can be done, though. I first learned to fly in an S-6, so I have a sweet spot for Rans. I have been a passenger in an S-7 and I like it very much as well.

I do have a hangup on metal, because the Aeroprakt A32 my club can cruise at 115kn and stalls at 27(!!!) But that can only be bought key ready, and is too expensive unless I get lucky on the second hand market. I had plans building in stages, I have done a few projects like that in my life now (boats, bikes etc.) and I've learned to just keep working and focus on finishin milestones along the way.

So I think that a metal winged S-20 (Or an S-7? The S-20 wing supposedly came off the S-7. If the 141 fits the S-20, what would stop me - or how dangerous would it be - to put the 141 on the S-7?)

But the backup plan is the ICP Savannah. It's very popular, and there's a lot of guys to ask about everything. But it'd mean that taking my wet suit, sleeping bag and a tent, and do a 45 min hop over to my friend who lives near a nice surfing spot is a dream I probably have to abandon. I'd have to either leave a board there or lend one - Strapping it on the outside of anything this small is probably a very bad idea. It's more akin' to a "bring a toothbrush and find a hotel or cabin"-type plane. But that doesn't sound too bad either.

On the other hand. For me, flying is a hobby and about fun. Realistically, I probably won't to nearly as many trips or fly as much as I fantasize about now. So a used Savannah is probably what makes the most sense. But I'm sure the S-7 or the S-20 would do the job just well and fine. Compared to the Savannah they perform really well. And they're taildraggers. Another thing I don't need, but a skill I'd like to learn.
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