What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Weight savings ideas!

PropMan

Well Known Member
While starting this new build I'm planning on shaving as much weight off without compromising safety.
It would be great to have others input on what you did to keep your plane light.
My RV6 was 1025lbs empty, and the goal for this -4 is 875lbs empty. Here are some of the places that I know where there is room to shave off on this build compared to my -6.
1025 empty(RV6 weight)
-25 second seat
-20 lighten engine
-10 battery
-10 no primer inside
-20 titanium gear
-10 shorter wing
-20 narrow fuselage
-10 lighter glass work
-5** instruments
-10 paint
 
Weight savings

Not knowing you I have an observation of myself first of all and then other RV buds.

Some are willing to spend tons of money and effort but not on their own weight. Many of us could stand to lose a few pounds.

A cost analysis of the per pound saved would also apply to our waistlines as well as health

As I said, I?d be first in line needing this prescription!
 
Check my posts...

Hey Frank,

I built a 975 lb RV8A, and jut finished a 996 lb RV8 (a little disappointed about that, but it's painted, so at least no polishing!)

If you search my posts you'll find all the tricks I used to keep the weight down.

The plane had remarkable performance because it was so light.

Good luck on the build.
 
Not knowing you I have an observation of myself first of all and then other RV buds.

Some are willing to spend tons of money and effort but not on their own weight. Many of us could stand to lose a few pounds.

A cost analysis of the per pound saved would also apply to our waistlines as well as health

As I said, I?d be first in line needing this prescription!

Ha, yes indeed . I've been working on that too. Back down to 170lbs and a few more to go.
 
How about titanium Hi-loc fasteners for the wing center section and titanium plate for the straps? Bet that would save 5 pounds.
 
As I recall, the ribs all have circular embossed features for reinforcing. The centers of those circles are not removed at the factory though. But I think the plans say you can remove them to lighten the structure. Check the builder's manual to confirm.
 
How about titanium Hi-loc fasteners for the wing center section and titanium plate for the straps? Bet that would save 5 pounds.

I think fastners in general is a place where weight can be trimmed, in some cases it may just be grams. But if you count grams the pounds will add up
 
As I recall, the ribs all have circular embossed features for reinforcing. The centers of those circles are not removed at the factory though. But I think the plans say you can remove them to lighten the structure. Check the builder's manual to confirm.

Yes, I did this on my -6
 
Hey Frank,

I built a 975 lb RV8A, and jut finished a 996 lb RV8 (a little disappointed about that, but it's painted, so at least no polishing!)

If you search my posts you'll find all the tricks I used to keep the weight down.

The plane had remarkable performance because it was so light.

Good luck on the build.

Lance , looks like you saved weight in the glass area. I had looked at the wing tips and planned on shaving a few inches off them also.
 
Titanium saves a little

I have 90% of my bolts and fasteners Titanium in my -4 (I'm in an industry where they are readily available) I used Titanium Hiloks everywhere I could, but I doubt I shaved nearly as much weight as everyone thinks I did. It weighs in around 940, and Im good with that.
 
Not knowing you I have an observation of myself first of all and then other RV buds.

Some are willing to spend tons of money and effort but not on their own weight. Many of us could stand to lose a few pounds.

A cost analysis of the per pound saved would also apply to our waistlines as well as health

As I said, I?d be first in line needing this prescription!
I agree. Went on a diet, lost a little over 40 pounds this year. Can carry more in my 9 nowadays.
 
Lightweight

If you're going to remove the second seat anyway and want light, why not just build an RV-3? That'll save you about 100 pounds from the 4 and have the same engine. Probably take just as long to get either kit, or replacement pieces, since neither one is readily produced any more.
 
As mentioned before, weight savings most notably observed on the flight line can be accomplished by a bathroom scale and mirror. Your wife or girlfriend will love you for it.

Cheers, Hans
 
I have 90% of my bolts and fasteners Titanium in my -4 (I'm in an industry where they are readily available) I used Titanium Hiloks everywhere I could, but I doubt I shaved nearly as much weight as everyone thinks I did. It weighs in around 940, and Im good with that.

Can you estimate how much you saved?
 
I've spent a preposterous amount of time dreaming about radical ways to lighten my RV-4.

Here's a few that nobody's listed so far:

Carbon roll bar
Carbon main gear and tail spring
Carbon push/pull control tubes
Titanium heim joints
Carbon empennage
Carbon flaps and ailerons
Carbon control sticks
 
If you're going to remove the second seat anyway and want light, why not just build an RV-3? That'll save you about 100 pounds from the 4 and have the same engine. Probably take just as long to get either kit, or replacement pieces, since neither one is readily produced any more.

I want a higher Vne. Going to clip the wings HR2 style, increase the fuel capacity, and 200+ HP O360. Plus i will still have room for a back seat if later i want.
 
Of coarse the obvious. If you want to be light, best way is cut the comforts and nice-to-haves. Adds up way faster than titanium fasteners and lightening holes.

Empty Weight items (all weights below are quick guesses)
-Fixed pitch wood prop -25 lbs
-No interior except seat cushions (cloth not leather) -20 lbs
-No carpeting or sound/fire proofing -3 to 10 lbs
-No vacuum system -5 lbs
-No autopilot -5 lbs
-Electronic ignition vs mags -5 lbs
-Cheap (less ply) tires. Some of the RVs are using the high ply 200 mph ones because they get longer life. -6 lbs
-No cabin heat -2 lbs
-Day only (no position lights) -3 lbs
-Polished, not painted -30 lbs
-small and thin fairings (gear to fuse, gear to wheel pant, fuse to tail, fuse to wind screen) -5 lbs
-no redundant displays, back up instruments, and back up batteries. -5 to 10 lbs
-no Dual breaks -2 lbs
-no Dual stick -1 lb
-no electric trim and/or flaps -1 lb

Don’t forget items probably booked in useful load. All adds into weight in flight. None required though they are nice-to-have. Many of these Maybe should not be in plane all the time.
-Supplemental air
-tools
-iPads
-chocks, gust lock, tie downs, covers
-fire extinguisher
-manuals
-logbooks
-blankets, pillows, and cushions
-remote ADSB In

And a big one but very emotional and safety related.
-fly with min fuel required for expected flight. -100 lbs. (when flying local for fun don’t need full tanks)
 
Last edited:
Go on diet and exercise more, get back to your ideal weight.... Losing 10, 20,,,, ahaa 30 lbs on the plane is the same as losing weight on your frame, and it gives you health benefits.... Just a thought. :D (Merry Christmas, note to self step away from the Pie)

As far as air-frame weight... simple, less.... fixed wood prop, 160/180 HP, modest panel, modest interior, min paint coats.... day only,

In my early RV days I flew a few fixed pitch wood prop, 150/160, basic day vfr only RV's. They were a delight.
 
Last edited:
Here's a Few

I've been trying to save weight wherever possible on my RV-6 build and will share a few of the things I did. Now, I have a running bet with a few guys on what my empty weight will be, so you'll notice some of these get increasingly maniacal. I'll spare you the full on weight-psycho stuff until I weigh in and either have to use it or not.

A lot of people mention the wood prop saving 25-30 lbs, but then go and put a 18lb crush plate on the nose for CG reasons :rolleyes: With that in mind, I focused my weight savings at the tail. Ideally allowing me to run a composite prop without a weight up front.

Starting at the tail:
-Using the classic RV-6 VS and rudder (no counterbalance) (sorry 7/8/9 builders, not an option).
-Built a new set of .016 elevator skins using RV-7 counter balance arms which are longer, and position the CW horizontally, thus requiring less counterweight. (The combination of elevator counterweight and skins will be nearly a 2lb reduction alone)
-Turned a titanium tailspring on the lathe (1lb saved).
-Planning to do a billet tailwheel fork and Ti axle.
-Scallop the mating flange of the fairings and pop rivet instead of screw on.
-MS-21042 instead of AN-365's
-Round and taper those corners on your 1/8" angles and straps in the tail.

I'm hoping that by pulling 4-5lbs out of the aft-most point on the aircraft, I'm able to run a ground-adjustable composite prop without any extra weight up front (saving another 10-15lbs). Engine is a carb'd O-320.


Then of course are all the easy ones throughout the rest of the aircraft:
-Build a taildragger :cool:
-MS-21042's instead of AN-365's
-Minimal interior
-Single EFIS Glass Panel with LRU's mounted as close to power/data hub as possible.
-Careful and efficient wiring throughout (See AC-43.13B for calcs and help on minimizing wire size).
-Fuses instead of circuit breakers
-Single (or double) set of seat back hinges. Single seat back angle per side on the cross bar (speaking of which, lighten that piece of angle up!)
-Lithium battery (Easy 10lb saved compared to an Odyssey, 20lb lighter than a concord).
-Aluminum battery box (see RV-14 battery box if using an odyssey).
-Aluminum hard lines instead of rubber hose wherever feasible.
-Single set of brakes. (And throw those master cylinders in the lathe or mill to get rid of all the extruded material between the ports.)

Sometimes I ask myself if it's worth it... However, flying a heavy and lightweight RV back to back often reminds me that it is not in vain.
 
Go on diet and exercise more, get back to your ideal weight.... Losing 10, 20,,,, ahaa 30 lbs on the plane is the same as losing weight on your frame, and it gives you health benefits.... Just a thought. :D (Merry Christmas, note to self step away from the Pie)

As far as air-frame weight... simple, less.... fixed wood prop, 160/180 HP, modest panel, modest interior, min paint coats.... day only,

In my early RV days I flew a few fixed pitch wood prop, 150/160, basic day vfr only RV's. They were a delight.


Funny as heck and True. It's nice to build a light plane but so many focus on buying things that are a few pounds lighter (a battery for example) to save on overall weight and never give a thought about losing 10 pounds from the gut :D. I know after this past Holidays my plane gained at least 10 more pounds every time I flew :rolleyes:
 
Having built a 998 lb -9, I'll chime in.

The +9 had a longer fuselage and wing, so you are already ahead of me.

Tip-up taildraggers are supposed to be the lightest combination, so start there.

Small engine helps, a narrow deck O-320.
Composite two bladed prop (Catto?)
P-mags (1.5 lbs lighter and no complex electrical system needed.
ECi tapered cylinders (1.5 lbs lighter than stock, IIRC.)
Smallest starter you can find.
Punch lightening holes on the seat backs.
Punch lightening holes in the bulkheads.
Use the all metal locknuts, not nylocks.
Thin washers, were you can.
Skip the electrical system altogether!
Replace all fiberglass parts with carbon fiber or aluminum, which may be lighter.
Weigh tire, wheel, and tube combinations.
 
Weight a minute...

Frank,
My Early model RV4 weighed 915Lbs with no fuel or oil when the FAA DE looked at the scales during my inspection. Rather than any cool building shortcuts, I simply did without as my wallet was the LIMFAC (as we say in the military).
No paint, starter, aircraft battery, alternator, lights with a very basic interior and Fly Market avionics.
Flight characteristics with an 0-320A and Sterba Wood prop? Superb.
Cost? Under $25K (1995 dollars)
Even now you could get a RV4 in under 975 with no frills...
Yes, it can be done...
V/R
Smokey

PS: That same RV4 now with paint and avionics MT FP prop 0-320E2D weighs 955lbs, a testament to lightweight accessories and new owner diligence.
 
Last edited:
My 8 is 542kg (1195lbs for you Yanks) M/T. I have all the creature comforts, I didn't want to fly around in a cold noisy T model Ford:D I dropped 10kg's personally, win win -:)
 
Last edited:
Here's a Few

I've been trying to save weight wherever possible on my RV-6 build and will share a few of the things I did. Now, I have a running bet with a few guys on what my empty weight will be, so you'll notice some of these get increasingly maniacal. I'll spare you the full on weight-psycho stuff until I weigh in and either have to use it or not.

A lot of people mention the wood prop saving 25-30 lbs, but then go and put a 18lb crush plate on the nose for CG reasons :rolleyes: With that in mind, I focused my weight savings at the tail. Ideally allowing me to run a composite prop without a weight up front.

Starting at the tail:
-Using the classic RV-6 VS and rudder (no counterbalance) (sorry 7/8/9 builders, not an option).
-Built a new set of .016 elevator skins using RV-7 counter balance arms which are longer, and position the CW horizontally, thus requiring less counterweight. (The combination of elevator counterweight and skins will be nearly a 2lb reduction alone)
-Turned a titanium tailspring on the lathe (1lb saved).
-Planning to do a billet tailwheel fork and Ti axle.
-Scallop the mating flange of the fairings and pop rivet instead of screw on.
-MS-21042 instead of AN-365's
-Round and taper those corners on your 1/8" angles and straps in the tail.

I'm hoping that by pulling 4-5lbs out of the aft-most point on the aircraft, I'm able to run a ground-adjustable composite prop without any extra weight up front (saving another 10-15lbs). Engine is a carb'd O-320.


Then of course are all the easy ones throughout the rest of the aircraft:
-Build a taildragger :cool:
-MS-21042's instead of AN-365's
-Minimal interior
-Single EFIS Glass Panel with LRU's mounted as close to power/data hub as possible.
-Careful and efficient wiring throughout (See AC-43.13B for calcs and help on minimizing wire size).
-Fuses instead of circuit breakers
-Single (or double) set of seat back hinges. Single seat back angle per side on the cross bar (speaking of which, lighten that piece of angle up!)
-Lithium battery (Easy 10lb saved compared to an Odyssey, 20lb lighter than a concord).
-Aluminum battery box (see RV-14 battery box if using an odyssey).
-Aluminum hard lines instead of rubber hose wherever feasible.
-Single set of brakes. (And throw those master cylinders in the lathe or mill to get rid of all the extruded material between the ports.)

Sometimes I ask myself if it's worth it... However, flying a heavy and lightweight RV back to back often reminds me that it is not in vain.
Good day. Did you find a titanium tail wheel bolt. I would love to purchase one. Thanks.
 
Back in gth da
Decrease wt

Fly nude save 1.5 #,s
Ahaaaaa don't you always fly naked?

Good day. Did you find a titanium tail wheel bolt. I would love to purchase one. Thanks.

This is a old thread. I had some titanium fasteners in my first RV.... I lived in Seattle and Boeing surplus had barrels of loose unsorted new hardware they swept off the hanger floor. They STOPPED doing that. People bought the titanium and aircraft hardware by the buckets for pennies. They would sort it, package it, sell it for full price. The problem with titanium fasters is they are expensive. I was in the late 80's.

I think all the normal ways to save weight have been mentioned. However some comments are extrema IMHO and sacrifice the "total performance" mission. If weight is your goal (besides a diet for the pilot), O320, wood prop, no primer, no paint, simple day VFR equip and stick to plans.... The RV6 did not have beaded lighting holes cut out in wing ribs. Manual said it was optional to cut them out. By all means cut those out.... Bottom line Van's plans will build a light plane. Van's prototypes are all light, but not dripping with every do-dad, sparkly bells and whistles.
 
Last edited:
The other factor not mentioned in this thread is how much TIME it would take to deviate so far from the plans. Not to mention loss of $$$wallet$$$ weight! If you want a great design that flies well and in the mid 900's range, stick to the plans. Or as Van would say "Build in lightness." You will have a great airplane to fly and money left over for fuel and other minor necessities.....

I race time trial bicycle racing. It is amazing to see people buying $$things$$ to shave grams off the weight of their ride but neglect the weight and fitness of the engine! I admire those pilots who have lost tens of pounds off of their pilot weight: that makes a huge difference! It isn't just the weight of the airplane...... 😊
 
As I recall, the ribs all have circular embossed features for reinforcing. The centers of those circles are not removed at the factory though. But I think the plans say you can remove them to lighten the structure. Check the builder's manual to confirm.
I did this on mine and it was a 2.5 lbs savings. I weighed the circles I removed.
 
Last year I got my 6 back in the air after a diet and managed to save 80lb, but it took 20 months to achieve. Much of that was fitting a new cowl that required significant tweaking to make it fit properly. Be aware that the current production cowls are significantly heavier (several pounds) that the older - 2010 vintage - cowls, and also heavier than the really old single skin cowls. I set a budget for how much I was prepared to spend to save 1lb to gauge whether an idea was workable. I started at $100 per lb, but soon had to up that to $200 per lb. The most significant saving is from a carbon prop, I removed a Hartzell, fitted a Whirlwind, and saved around 25lb, but the cost was high. However, its the only way to save such a significant amount (and it looks great). A Lithium battery will save 11lb over a PC680 and it great value. Various engine mods can save around 20lb (light weight sump, lighter starter ring, vac pad alternator, electronic ignition in place of mags) but will cost more than $200/lb. Many smaller items will add up to a few lb, its always good to throw out the heavy or unused equipment and swap out lighter stuff. However sometimes the light weight stuff just isn't up to the task. I did fit an autopilot and use it often. Although it costs around 5lb it is worth it for me. If you don't plan any night flying delete the lights, the wire to the wing tips weighs a bit. Weight savings in the airframe are never a bad idea when building as they are difficult to realise later. It always pays to estimate the cg shift from any change as it is possible to move the cg too far back and seriously limit the baggage capacity. Modern instruments & radios weigh less and consume much less power than the equipment available 20 years ago. I really enjoyed the process.
 
SNIP .... Much of that was fitting a new cowl that required significant tweaking to make it fit properly. Be aware that the current production cowls are significantly heavier (several pounds) that the older - 2010 vintage - cowls, and also heavier than the really old single skin cowls.

I have only two points of reference, early Van's polyvinyl gel coat (what I think you arre calling single skin). And mid 2000's (pre 2010), which has a core and inner outer skins, with no gel coat or primer. I can say the early GEL COAT ones especially after you primed, painted them were heavy. The vintage (new old design 2000's cowl I have with a core is lighter by a lot than the old Gel Coat Single skin...

Why the weight gain in new cowls? I find it hard to believe the old "single skin' Gel Coat cowls were lighter than current production cowls, but I have no new production cowl to compare. If the new cowls come primed that might account for some of that weight? Primer and paint adds weight. Back to the question why?

Great write up and weight savings program... I have flown many RV's, and back in the day 0320, wood prop, VFR, day, simple interior and paint.... were a joy to fly, well within van's suggested empty weight. Then I flew heavy ones... Night and day.
 
Last edited:
I have seen 4 different cowl constructions over the last 25 years.
The early, white, single skin & gel coat that everyone thought was heavy, and cracked up around the exhaust outlet - or mine did at least.
The first generation cored cowls that were probably a wet lay up, came out a light brown colour, and were significantly lighter than the single skin type.
The 2nd generation pink variety. I don't know much about these as I've only seen pictures.
Current production grey cowls that are built from pre-preg cloth and have a lot more glass in them than the 1st gen cored cowls and so are significantly heavier. I don't have an unmodified single skin cowl or current production cowl to compare, but they are a comparable weight with the current production version being much stiffer (and therefore better).

Lighter aircraft are almost always much better to fly than something 50lb overweight. Makes sure everything added to the airframe earns its place. If it isn't fitted it won't cost anything, won't weigh anything and won't need maintenance.
 
I have seen 4 different cowl constructions over the last 25 years.
(1)The early, white, single skin & gel coat that everyone thought was heavy, and cracked up around the exhaust outlet - or mine did at least.

(2) The first generation cored cowls that were probably a wet lay up, came out a light brown colour, and were significantly lighter than the single skin type.
(3) The 2nd generation pink variety. I don't know much about these as I've only seen pictures.
(4) Current production grey cowls that are built from pre-preg cloth and have a lot more glass in them than the 1st gen cored cowls and so are significantly heavier. I don't have an unmodified single skin cowl or current production cowl to compare,

My engine cowl is green with core that looks brown under light.... I am assuming you are calling it 1st Gen core layup. I would say it is way lighter than solid laminate gel coat. Not arguing but a data point I did weigh them, I got about 16.5 lbs total Wt. for my RV7 cowl (with Carb scoop on bottom), total weight for both top and bottom.

DOES ANYONE HAVE A OUT THE BOX WEIGHT OF THE NEWER RV7 COWLS?

I don't have my solid laminate RV-4 cowl, sold plane long ago. Those old cowls were heavy, however the plane had very nice single stage jet glow urethane paint and a lot of prep (primer, sanding, priming)). That adds a few pounds.

Pre-Preg fiberglass is not common, pre-preg graphite yes. You think it is wet layup? Agree. Likely. I'd go further and say I did not think Van used or uses now any prepreg for any vintage or current generation of cowl, but I'm not up on the latest kit stuff. Resin injection, vacuum bag is another option. It would be interesting if someone would weight current RV6/RV7 cowls (I think RV9 is same as well).

Wet layup can be light-ish with skill. I took a workshop at Sun N Fun fly in a few years ago. I am not a composite fabricator by ant stretchy. The instructor gave you only so much resin, sparingly, a little at a time. You had to work it in and recognize dry areas. You only added as necessary sparingly. I would have globed it on, if left to my own devices. Once done peal ply was added. It came out nice. Then I saw a demo in another workshop or resin injection making wheel pants. Went through making plug and mold over the whole week show. Pretty cool.

The other composite parts in my early RV7 kit, wingtips (core layup) with Gel-coat. The tail intersection/tip fairings are gel coat and old school polyvinyl likely. I sanded most of the gel-coat off. My gear legs Team Rocket and wheel pants, Sam James... all wet layup solid laminate, no coating but decent surface, min pin holes.

Early gel coat engine cowls, like my RV-4 I thought were heavy. The gel coat cracking and polyvinyl fiberglass shrunk over time with engine/exhaust heat. It worked but it did not like heat... It was a poor choice vs epoxy, but it was the 1970's and 80's....boat / hot tub technology got the job done, inexpensive, easy to work with. A friend at the time was building a Long-EZ, was horrified at polyvinyl glass.... Ha ha. They are not structural.
 

Attachments

  • Cowl 1.jpg
    Cowl 1.jpg
    232.3 KB · Views: 19
  • cowl 2.jpg
    cowl 2.jpg
    152.5 KB · Views: 17
Last edited:
I have been focusing my weight savings efforts the tail lately so that my passenger doesn’t have to decide between bringing the hairbrush, or bringing the toothbrush!
(It’s the one spot on the airplane which a few pounds significantly effects baggage capacity.)

I spared 1.75lb by switching to a 4” tailwheel and truncating the factory fork.

I saved another .4 lb by machining my own set of steering springs based on Brent Anderson’s Tail Lynx. These are however, machined from 6-4 titanium, use a smaller spring (while retaining the same travel and spring rate) and weigh about half what the originals weighed.

These are the first steps I’ve taken in what will be a long road!

Next “low hanging fruit” will be to swap out all my rudder fairing screws/nutplates for pop rivets. The next hi-hanging fruit, will be shared once it’s flown.
 

Attachments

  • 80992746-00AA-4790-A2B8-6DB095C6F422.jpeg
    80992746-00AA-4790-A2B8-6DB095C6F422.jpeg
    2.8 MB · Views: 45
I spared 1.75lb by switching to a 4” tailwheel and truncating the factory fork.

I saved another .4 lb by machining my own set of steering springs [SNIP] from 6-4 titanium,

Next “low hanging fruit” will be to swap out all my rudder fairing screws/nutplates for pop rivets. The next hi-hanging fruit, will be shared once it’s flown.

Reducing tail stinger will change handling, not radically but it will change function (albeit minor).

The Titanium tail springs, who knew... that is not too shabby. (y)

How will you fit pop rivets where you already have screws, replace the metal strip nut plates are on and do fiberglass repair.... I used pop rivets from get go, weight crossed my mind, but some parts don't need to come off often. Worst case you drill the pop rivet out. It is just practical and once painted it looks great.
 
Reducing tail stinger will change handling, not radically but it will change function (albeit minor).

The Titanium tail springs, who knew... that is not too shabby. (y)

How will you fit pop rivets where you already have screws, replace the metal strip nut plates are on and do fiberglass repair.... I used pop rivets from get go, weight crossed my mind, but some parts don't need to come off often. Worst case you drill the pop rivet out. It is just practical and once painted it looks great.

Existing Ti stinger options don’t allow much impact on loading before the knuckle slams into the rudder fairing, not to mention the caster angle increasing due to the extra flex. That’s part of what I plan to address before implementing that option.

Spot on for my plan of action to rivet the fairing. While I have it off I’ll be deleting the tail strobe mounting pad from it as well.
 
So… Propman, how about an update? Have you been faithful to the goal of a super light build? Have you flown yet? Or how is the project going? Give us an idea of the weight reduction steps you incorporated.
 
Back
Top