[meloosifah]

Well, I have been lurking around here for a couple of years reading virtually every post, taking notes, making plans and generally plotting to take over the world. I am finally taking the plunge and buying an RV-8 kit. I should be picking up the empennage kit (already completed) and my Cleveland tools in a couple weeks and my wings a couple weeks after that. The wings are a started slow build kit.

I have been scheming and dreaming of this for almost 5 years. If anyone has any suggestions for me as I begin this kit please don't hesitate to speak. This will be my first project of this sort. I used to restore air cooled Porsches but never an aircraft.

I am thinking of adding a few things to this IFR ship as I go-
Grove airfoil gear
Extra fuel
Inverted fuel/oil
Upgrade the brakes, tires, tail wheel
Generally try to apply every go-fast upgrade that I can

I have searched high and low but have not found a list of proven mods that people have tried and proven to increase speed, performance, efficiency, etc. Anyone have one? Looking to make this thing as fast as I can on a parallel valve io-360 without creating a maintenance nightmare so I figured I should focus on the airframe more than the power plant. Any thoughts or suggestions?


A couple of questions for the group:
1 - Thinking of adding auxiliary fuel tank in one wing and smoke oil in the other. Any thoughts or suggestions?
2 - Any -8 builders in Indiana near Anderson?
3 - Anyone nearby with a flying -8 that would be willing to let me try it on for size (and maybe even take me up for short flight) if I promise not to drool on it too much?

Thanks to all who posted the great info that I have been sponging on for the past several years.

Blake

Semper Fi

 

[Andy Hill]

I hate to say it, but you did ask for <<If anyone has any suggestions for me as I begin this kit please don't hesitate to speak. This will be my first project of this sort.>>

1. <<the empennage kit (already completed)>> Problem 1 - the Emp Kit is a great learning phase, with decent instructions, covers the construction principles, and mistakes are cheap and easy to rectify. You do not want to be "learning" on the wings
2. <<Generally try to apply every go-fast upgrade that I can>> I would advise the complete opposite if you want an easy / quick / cheap build. The "stock" RVs, especially the 8 are excellent aircraft, and most of the "mods" are not worth the effort.
3. <<I have searched high and low but have not found a list of proven mods that people have tried and proven to increase speed, performance, efficiency, etc. Anyone have one?>> As above!

Re your suggestions:
<<Grove airfoil gear>> Probably the 1 exception to the above. Well worth the weight savings.
<<Inverted fuel/oil>> Really think what you want here. With an IO- engine, inverted fuel is not really needed unless you have Full Inverted Oil, and want to do 15s+ inverted... few do. Inverted Oil not really necessary unless you are into head banging aeros / competitions (and if either, the RV is not really a good choice).
<<Upgrade the brakes, tires, tail wheel>> Brakes? Why / what for? Tyres maybe - definately the tubes (Airstop). Stock Tail Wheel is fine, but a Bell fork etc. is worthwhile.

If you want a "nice handling" RV to fly, #1 priority should be weight saving. Don't add anything unless really necessary, aim to eliminate as much as possible. This is the one "mod" that is definitely <<proven to increase speed, performance, efficiency, etc>>

 

[dav1111]

The first thing you need to do on the canoe part of the fuselage build is to build a rotating stand so that you can have access to all of the inside of the canoe during the build without having to climb in the airplane. Trust me, it will be the best thing about the build.

And do not mount the gear legs or remove it from the rotating stand until everything inside the fuselage is completed and in place.

 

[Neal@F14]

Stock fuel capacity is plenty enough... 42 gallons.

Stock brakes are fine too. As was mentioned, the Airstop or LeakGuard inner tubes is a very worthwhile investment so you don't have to remove the wheelpants nearly as often to add air. The stock tires are good enough for flying off the phase-I hours and your first couple hundred hours after that too, then upgrade to Goodyear Flight Custom III premium tires.

For the tailwheel, a "Rocket Link" is the way to go for sure. You'll throw rocks at a chain setup once you've experienced a Rocket Link for tailwheel steering. Also a Bell, API or Screaming Eagle tailwheel fork is a very nice upgrade too. The stock tailwheel is fine on an RV-8 too, but I really like my composite "Deluxe" tailwheel from Flyboy accessories. It saves a few ounces of weight back there and has sealed bearings so it doesn't sling grease all over and get grungy full of grass and dirt.

An air/oil separator is probably all you'll need if you want to help keep oil off the belly, but even that isn't really necessary.

Build it light, straight and aerodynamically clean and it'll go as fast as an RV-8 can.... just how quickly do you want to reach Vne anyway You could make it a "fastback" for a couple more knots, and a distinctive look.

I own and fly an RV-6 but I helped a friend build a really nice and fast RV-8 and got to put about 100 hours on it. It's a wonderful fun and nimble X-C machine, IFR capable especially if you equip it with a good autopilot like a TruTrak Sorcerer.

And Welcome to the VAF forums!!!

PS: If you equip it for smoke, then don't bother with the air/oil separator since you're gonna be cleaning smoke oil off the belly anyway... I've got the Smoking Airplanes rig on my RV-6 and it keeps the belly well-lubed whenever I use it. (and smoke oil is breathtakingly expensive too)

 

[Berchmans]

New to the game

I am in the process of completing my first RV8, fuselage 90%, wings on, ordered engine and prop yesterday.

Now for my 2 cents. I have been flying in Alaska for over 30 years and I can tell you that virtually every plane out there has more duration than my blader...I don't believe extended fuel is worth the effort. If you want smoke I would go with a removable tank either in the aft or forward baggage...99% of the time you will not be using it. IFR is great but I personnaly did not go to that extent, again the vast majority of my flying is VFR and I am not sure I would want to be doing true IFR in a single engine, 24 foot wing span airplane. In all my flying when the weathers bad I don't go or don't continue.

As to mods that save weight I think those are great.

My kit was slow build. I bought a finished emp and went from there. No sweat. When I do it again I will go slow build once more, because building is really fun.

One other thing. Don't skimp on tools or cleco's you want a lot of clecos...

 

[n5lp]

...For the tailwheel, a "Rocket Link" is the way to go for sure. You'll throw rocks at a chain setup once you've experienced a Rocket Link for tailwheel steering...

Well some people feel that way but that may be an iffy prediction. I have experienced a "Rocket Link." I don't throw rocks at it because I respect the company and the people that prefer it. I vastly prefer my stock loose chains.

I flew a fantastic RV recently that was of a type I hadn't flown before. The link was the main distraction. Put some screen door parts on that baby and it would have been really sweet!

 

[Bob Kuykendall]

Some additional suggestions based on having helped build a nice RV-8:

...Extra fuel...

Realistically speaking, you don't need any more fuel endurance than bladder endurance. Stopping to pee is a really good excuse to get out and stretch, which is a good thing for fatigue resistance on long trips.

Also, auxiliary tanks are easy to talk about, but not so easy to engineer and install. The vibrations and sloshing in airplane tanks can be real punishing, way beyond what you might expect. Vans' riveted aluminum tanks made from tempered sheet seem to be pretty robust, but this article on the Falco site shows some of the issues encountered when developing tanks from scratch.

...Inverted fuel/oil...

Like others, I wouldn't do inverted oil unless I was into head-banging aerobatics, and then I'd get an Extra 300 and call it done. Inverted oil systems are expensive, complicated and bulky. They add a lot of under-cowl hoses and valves and stuff, and they introduce many potential failure points. My advice: Put a flop tube in one wing tank and call it done. That has met the needs of the vast majority of RV-8 operators.

...Upgrade the brakes, tires, tail wheel...

Going to the next size larger tires for the stock wheels is handy for rough strips, and the drag penalty is miniscule. The stock wheels and brakes are fine. There are several tailwheels that folks like better than the stock unit.

...Generally try to apply every go-fast upgrade that I can...

Just know when to say when. Airplanes are simple, but building them is not. Making changes is the primary reason for slow builds. Even a slow RV-8 is a heck of a lot faster than one not finished.

...I have searched high and low but have not found a list of proven mods that people have tried and proven to increase speed, performance, efficiency, etc...

The RV-8 is already a pretty tightly optimized solution set, and there aren't many ways of improving on it that don't make some other aspect worse.

Thanks, Bob K.

 

[Wayne Gillispie]

Five years of dreaming for me too. Two years of building. Dang, if the -8 is like my -10, it will be difficult to improve much. Cruising around yesterday with a new "just soloed" pilot, sipping 8.9 gph at 142 KTAS at 2500' msl. I am so glad I did not make a bunch of mods. I am wondering now if I really needed all that $FR stuff. The two legs in 76.9 hrs that I could not make so far, I would not have flown $FR anyway due to TS. I may change my mind after this winter. Luckily I have a boss that is very understanding if I need to spend an extra 3-4 days in Florida or Osh. I don't even have to call me.

Welcome and have fun with the build whichever way you go...Heavy/light, vfr/ifr, slow/fast, less expensive/more exensive, no prime/prime, two years/ten years.

 

[Toobuilder]

My cruise fuel burn is a hair over 7 GPH @ 165 KTAS with an angle valve/CS airplane. 42 gallons is a long time in the air! Build it light and install a relief tube.

 

[meloosifah]

Thanks!

Great tips!

It sounds like I may want to think about the inverted oil. I plan to spend some time upside down but probably not hours at a time!

IFR is mainly due to a couple of airports that I plan to use regularly, are frequently socked in. I don't plan on heavy IFR flight but would rather have the option.

The increased fuel capacity is really independent of bladder range. I just hate being dependent on high priced fuel on cross country trips. I have dual tanks on my diesel truck and rarely use both tanks in a cross country drive before refueling but just increases my options on when and where to fill up. I am also a very cautious person and would like the increased reserve capacity that 10-20 gallons would bring.

I definitely like the idea of light weight. I don't want any unecessary weight but also don't want to compromise my mission objectives.

I know that the empennage is the "learning" kit but I bought a whole bunch of stuff and it was included. I will just do some practicing ahead of time and go slow.

Great idea on the rotisserie. Anyone with a good design?

With regards to "go fast" I was thinking
Reduced weight
Tail wheel fairing
Sam James (although I cannot find any definitive testing despite much research)
All lighting and antennas (that I can) recessed/hidden/flush
Anything else I can come up with!

Thanks for all the responses! I greatly appreciate it. I have big plans but it helps to have other perspectives to keep me in the realm of reality.

Blake

Semper Fi

 

[mannanj]

Build

The -8 is pretty much optimized for the 180-200hp Lycs. You're not going to get much more speed without exponential increases in horse power. The Sam James cowl, plenum and wheel fairings will help by lowering drag, though it will increase build time slightly. Lowering drag is about the only way to increase speed on these planes.

Dan Horton, Bob Axsom and others have made numerous posts on cooling drag.

As others have said, build it light. Forget the fancy upholstery, carpet and other "doo-dads" that aren't necessary. Forget the inverted oil, just one flop tube in one fuel tank will get you through all the "gentlemens" aerobatics.

As for increased range, that's a mixed blessing. The tube type tanks that fit in the leading edge ribs give you about 10 gal. extra along with the decreased "usefull" load.

No need for a relief tube, "Travel John" bags from AC Spruce and other retailers work well.

All that said, build the plane you want---not what others say you should build. Build what "rings your chimes" when you open that hangar door

 

[Bob Axsom]

Well you want another view?

I have removable tip tanks that increase the capacity on our RV-6A to 55 gallons and the endurance by 1.6 hours with wide open throttle and 2450 RPM. I always urinate before flight and I can go all day if I have to without needing to repeat. Maybe its a different life style for baby boomers or something? The need to use a restroom was only a problem for me once and another time for my wife and we each understood the cause and it never happened again - like no coffee before flight. I agree that the fuel capacity is minimal - more is better.

Light weight is NOT the best way to increase speed - weight difference in the RV world is not going to increase cruise speed much - the rule of thumb is 1 kt per 100 pounds. Weight has a more significant effect on climb but nothing gross. If you do not want to sit on bare metal it is OK to add seat cushions, etc. When we built our RV-6A we installed full upholstery (me with cloth, carpet, pads and cushions bought from Becki Orndorf and 3M 377 adhesive not some upholstery shop) to make it the way we wanted it, sound deadening pads under the carpet, and on the back of the firewall.

You obviously have building experience but I still would recommend a short course in aircraft aluminum fabrication just to knock off the rough edges of learning the skill.

If you have ideas for making your plane go faster implement them in a way that will allow you to back them out if they don't work as expected. Many do not work as expected for me so I speak from experience. If you want to go faster than stock it is one of the most satisfying things you can do, to conceive ideas, implement them, test them, keep them if they work, throw them out if the don't and build on success. Don't strive for mediocrity if you feel the need for speed. Then bring your bird to a SARL race and see how she stacks up against her peers. I have increased the speed of out RV-6A 13 knots over the original base line speed in its original configuration and I am still working on it and it gives me a reason for living in these bland uninspiring retirement years. Different strokes for different folks.

Bob Axsom