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Light and simple RV-6

invertedflyby

I'm New Here
Hi,

I am thinking of building an RV6 and am wanting to keep it as light and simple as possible. 180hp 3blade performancepropeller wood prop. I don't even want a carb heat so I was thinking IO, but I've heard you can get away with no carb heat on a carb'd Lycoming, is that true? Would it be possible to get one to come in at 973lbs?

What would the recipe be to do that? Tip up, no vacuum pump, etc?

Thanks.
 
Please don't take this as a criticism; I'm not critical but curious.

I've read others' posts wanting to be as light as possible, and am just wondering what the motivation is.

Van's published data indicates a 1 mph loss of speed when going from solo weight to gross weight, not a perceptible difference unless you're racing your plane. I'm sure the lighter plane will get off the ground some number of feet faster and climb some number of fpm faster too.

What are the biggest advantages for you in trying to decrease your plane's weight...?
 
Please don't take this as a criticism; I'm not critical but curious.

I've read others' posts wanting to be as light as possible, and am just wondering what the motivation is.

Van's published data indicates a 1 mph loss of speed when going from solo weight to gross weight, not a perceptible difference unless you're racing your plane. I'm sure the lighter plane will get off the ground some number of feet faster and climb some number of fpm faster too.

What are the biggest advantages for you in trying to decrease your plane's weight...?

Performance, particularly handling, acceleration, and climb. Also, useful load.

When I fly my RV-6 at <1250 lbs, it is far, far different than when the airplane is a hundred pounds heavier.

To the OP - unpainted, unprimed, with a simple glass panel and a wood prop, your goal is achievable.
 
I too would also like to know what the motivation is to make the lightest plane!

Is it just simply bragging rights?

I am flying a six now that comes in at about 1009 pounds.It has a full steam panel, VFR instruments, wood prop, 180hp carb'ed, a slider and only the fiberglass is painted.

Build it nice and build it with everything you need. It will fly just fine when you are done.

In answer to your question, I suppose you could get down to 973??? What is the significance of that number???

973 is really light. I doubt that you would feel any difference in handling between that plane and my 1009 pound "heavyweight"!

Besides, nobody walks around with scales in their pockets.

;) CJ
 
Just to comment specifically on the carb-heat. If you don't end up with FI, go ahead and keep the carb heat. Vans system is so simple that it adds very little weight. I would guess no more than a pound if that. It is a safety feature and not worth leaving off. You would save more weight removing the seatbelts, but I don't think anyone would consider that an option.
 
Light

Hi

I fully understand your reasons for wanting a light aeroplane..... more nimble, greater power to weight ratio, more useful load....... the list goes on and its a good objective. I would not leave off the carb heat we have had ice several times in a friends carbed 7.

What I would do to loose weight is compare glass panels with steam, no landing or strobe lights. An 0 -340 for extra Hp and same weight, lightest prop to take the HP.

Good luck!! It will be hard to achieve that figure.
 
First off, do a search, this topic comes up often. Your goal is extremely light but possible. (My -9, with its longer wing, came in at 990 but it started life with an O-290-D2.)

Start out with a tip-up taildragger as that is the lightest combination, according to Van's.

Hi

I fully understand your reasons for wanting a light aeroplane..... more nimble, greater power to weight ratio, more useful load....... the list goes on and its a good objective....

Ditto!

...To the OP - unpainted, unprimed, with a simple glass panel and a wood prop, your goal is achievable.

To that I would add no interior, just seats, no landing, position lights, or strobes. Go with the ECi O-360 with the tapered cylinders (Each cylinder is 1.5 lbs lighter than a Lycoming cylinder) and use the SkyTech XLT lightweight starter (6.5 lbs), dual Pmags (1.5 lbs lighter than a standard mag and easy to install.), and use the smallest alternator you can find. Install an integrated EFIS & EMS (The SkyView comes to mind because of its integrated transponder, radio, GPS, etc.) so you only have one instrument. Limit your CHT and EGT probes to one cylinder (I wouldn't do that but it will save you some weight.) Skip the fuel flow, MAP, AoA, stall warning, and all the other nice-to-haves that we just can't seem to live without.

Keep the carb and the carb heat. They are simple and light. If you go with FI you add bigger pumps, more plumbing, etc.

Keep your systems simple and don't go overboard with the options.
 
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I built 2 tip-up RV-6s between 1989 and 1993. One came in at 996 lbs. unpainted.
O-320, full gyro panel, dual brakes, nav, strobe, and landing lights, F/P wood prop, home done upholstery with "temper foam", com, loran C. Manual flaps and trim.
The other, an exact copy but with Sensenich metal prop weighed 1018.

After paint, Dynon D10A, #2 com, dual GPS, H/W ER tanks and 20 years of use airplane #1 now weighs 1040 lbs.

Don't even consider leaving off carb ht. It weighs practically nothing.
 
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Another "Definitely keep the carb heat" here.

Carb ice can and does occur in Lycoming-equipped RVs, and the "wimpy" carb heat system in a typical RV-6 like mine that picks up heat from a simple open-ended tube contraption that clamps around the exhaust crossover at the front of the engine is not really effective enough to melt carb ice that has already substantially formed, but rather needs to be used to prevent carb ice from getting a foothold in the first place.
 
Fit a Lithium nanophosphate battery.

On my Pitts this saved 21lb over the "plans" battery or 12lb over an oydesy / redtop one

620 cranking amps = 3lb in weight (!)

It's worked fine for 16 months / 100+ starts now on my 0-360

The cost is about $450 though - this being said, I've yet to find anything better in terms of cost per lb weight saved (apart from Salad perhaps ;))
 
Acheaviable with close attention to detail

Hi,

I am thinking of building an RV6 and am wanting to keep it as light and simple as possible. 180hp 3blade performancepropeller wood prop. I don't even want a carb heat so I was thinking IO, but I've heard you can get away with no carb heat on a carb'd Lycoming, is that true? Would it be possible to get one to come in at 973lbs?

What would the recipe be to do that? Tip up, no vacuum pump, etc?

Thanks.

My -6 came in at 1000lbs, o360, 3-blade Performance Propeller, Day-Night VFR. Now this was without paint and the plane is now painted and will be reweighed soon.
With close attention to details and stick to Simple Day VFR I feel your goal is achievable. With new less expensive glass panels now, battery technology and lighter glass components(cowl, wing tips, wheel pants) you should get very close.
 
Thanks for the welcome.

I appreciate all the input. I am not overly concerned about it being extremely light. I'm more interested in simple. I've learned that simple is better. I want something I don't have to think or worry about I can just go fly. Simple is cheaper, simple is less stuff to break, simple gives me a better chance of finishing one. I have a lot of other complex things in my life and want a dirt simple high performing airplane. I've heard a lot of people say they fly better when they're light and that's what I'm interested in. Plus I'm on a tight budget so can't really afford to put a lot of stuff in it.

I wanted to go FI or no carb heat for the single reason of one less control in the cockpit. But after this thread will definitely be going FI or having carb heat. How much more complicated is FI over a carb?

I'm okay with a tip up, no paint except the fiberglass, and a wood prop, a skyview, etc. That would be pretty cool. I do want night VFR though. I was thinking of converting the right half of the instrument panel into a giant glove box / storage area also.

I know 973lbs is strange. In this case it would be bragging rights. I have a Cessna 140A with 90hp that weighs 973lbs and got to thinking it would be cool to be able to say 'this one weighs exactly the same and has twice the hp'.

I just didn't know if that was doable, I have not researched weights before, I just remember seeing someone say that they should get a ride in a 1050lb one and it was a different plane. It sounds like 973lb would be difficult to get to, but if so that's fine.
 
Simple

I am on a similar path. My goal is inexpensive and relatively simple for many of the same reasons you state. I have also learned over many years of ownership that eventually everything on the airplane needs maintenance. I plan on using a Carbed O-360 with a fixed pitch prop. I have purchased the kit new but everything else used.

I have a Cessna 120 that weighs 915 pounds empty. As you probably know the 120 was the economy version of the 120/140. Mine left the factory without any interior or interior paint. Initially, the lack of interior gave me pause, then I realized it is perfect for me. Light weight, easy to clean, nothing to burn and never needs touched up. A stark contrast to the choice most people would make today when purchasing a new airplane.
 
I could reduce the weight of my build by 25 pounds if I could just stop eating so much Blue Bell Ice cream:eek:
 
I'm sure salads are better than ice cream for the gross weight of the planes!

DaAV8R, I'm bet it would be more difficult to build a 915lb 8 than a 973lb 6! That's an excellent weight for a 120/140. My dad had a 120, I was looking for a lightweight 120 when I bought the 140A. I only found junky ones in my price range over 6 months and the 140A popped up for just a few dollars more so I went over budget. I've thought about stripping the paint and removing the interior because it doesn't look good anyway.

Thanks for the advice everyone. I bought a completed 6A wings and tail a few months ago and would like to build the rest of the plane someday. If you run onto a cheap fuselage let me know.
 
Lighter they are...

Hi,

I am thinking of building an RV6 and am wanting to keep it as light and simple as possible. 180hp 3blade performancepropeller wood prop. I don't even want a carb heat so I was thinking IO, but I've heard you can get away with no carb heat on a carb'd Lycoming, is that true? Would it be possible to get one to come in at 973lbs?

What would the recipe be to do that? Tip up, no vacuum pump, etc?

Thanks.

Hi Brandon,
This is my 27th year in the RV world having built a 925lb RV4, 1190lb HR2 and my current 975lb RVX (RV6 Hybrid) I have been blessed with 3000+ RV flying hours and several lessons learned. From my first 2 airplanes and having inspected and flown 200 or so other RV's my conclusion? The lighter they are, the better and more fun they are to fly, trust me!

How do I keep them light? First, no frills keeps them simple, light and affordable. I don't care what they say about gross weight and empty weight performance. I've flown every model of the RV and the F16 and guess what, the lighter A model F16's fly better than any of the more powerful, heavier new models. Same holds true for any airplane, even RV's.

Techniques: 0-320 vs 0-360, I like the 0-320 as it's slightly lighter and can be rebuilt with 9,0:1 compression, has a shorter stroke and is a bit smoother. My RVX has an 0-360J (previous 0-320) the lightest 0-360 made.

Constant speed vs FP: Having owned both the FP for lower HP RV's is perfect. Simple, light and low cost. In fact it's 67 lbs lighter and around $5K cheaper depending on model. I like Craig Catto's composite props.

Starter/Alt: A true light nut would fore-go both items and hand prop but I used the lightest Sky-Tech available and a B&C SD8 mounted on the Vacuum pump pad. The Skydynamix Magnesium flywheel also saves 6lbs: http://www.skydynamics.com/sdflywheel.htm

Panel: KISS principle: My personal opinion is Autopilots are for airliners, Sport planes are for fun. Therefore, I didn't have one in any of my airplanes and never missed it. (I've flown alot of autopilots BTW) Instruments? I used a MGL Enigma and TruTrak ADI on the RVX with all LED lighting. 5.1A draw total.

Paint: One coat exterior with Vinyl trim, interior primer, no panels, trim or added weight. I do use Cool Max firewall protection.

RVX weight? 975 empty. Cost with used engine and Internet purchased avionics? Under $30K (2005 dollars)

How does it fly?
http://www.youtube.com/watch?v=Um3MZwrqPhQ

V/R
Smokey

Questions?
 
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Being a fanatic about anything in life is often viewed as a negative trait. The one exception to this is weight and airplanes, and for good reason - lighter is ALWAYS better. I stripped 40 pounds of sound deadener, accessory lighting and unused avionics out of my Hiperbipe as soon as I bought it and it really made a difference in the way it performed. I also offload fuel and fly only what I need for the same reason. Flying with full tanks makes an airplane a PIG!

There are a few good tips on staying light listed in this thread/site, but one thing to consider is limiting the use of flexible hose to the absolute minumum. I replaced much of the flex hose on the RV-8 with hard line and found a net savings of more than 6 pounds! I bring this up because many builders here default to flex hose like it was crack cocane. Hose is HEAVY and adds up fast.

Don't cut any structural corners, but stay fanatical! There is plenty of low hanging fruit to help you keep the weight down.
 
I didn't build a light weight to putter around the airport. I didn't try for the KISS principal, because I'd probably soon get bored. I built mine for comfortable cross country. I installed a constant speed prop, because it really does perform much better at high altitude airports. I installed auto-pilots because I could care less about maintaining +/-10' altitude, by hand, for hundreds of miles at a time. I painted, because I'm not into ugly unpainted RVs, and certainly had no intention of keeping up with the polishing method.

It's all what we want isn't it? It's a lot of money and time, for a putting around the airport sport plane.
 
IMPORTANT: RVs Need Carb Heat!

More than one RV has gone down due to carb ice. Yes in a PA28 you can get buy with out it on dry days.Don't try it in an RV.In a PA28 you have a muffler and a more open cowl. The cowl in an RV is tight and built to cool the standard carb heat set up is barely enough,Most RVs run straight pipes no muffler to hold heat in the cowl.I've trained for years in a PA28-151 and had a few instructors say don't worry about carb heat,I've noticed even they get nervous when dew point meets temperature (high humidity= carb ice)!

Of course all this is IMHO.
RHill
 
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