Please critique my RV-8 plan

[OzStriker]

Hi everyone,

I am very close to going ahead with an RV-8 order and would appreciate any input you would care to provide on the following.

Tooling is pretty much sorted.

My ideal aeroplane at the moment is:

- built light and relatively simple for day VFR flight, capable of negative G aerobatics
- I am building the aeroplane for just me to fly and for my wife to enjoy the ride in the back
- IO-360-M1B
- composite two-blade constant speed prop
- Christen inverted oil system
- 1 x Dynon 10" Skyview, a D6 backup (with its own battery and an alternate static source), Dynon autopilot, txpdr, COM, INT, Garmin GPS
- stall warning vane should a bird take out the pitot/AoA

I am geographically challenged here in Australia, so the basic plan is for two big shipments, the first of which will be the emp, wing, fuse and finish kit.

I am sure there will be 738,246 little shipments in-between as well

For my first shipment I am planning to purchase and modify as follows with Vans:

- fuel flop tubes x2 and delete standard pickups (Is there any safety reason to do this to just one tank and use that tank alone for negative-G aerobatics?)
- tie downs x2
- ground adjustable pedals
- manual aileron trim
- electric elevator trim
- Andair 90o fuel valve and delete standard valve
- Locking fuel caps and delete standard caps
- Metal air vent(s) and delete standard plastic vent(s)
- Fuel pump and filter
- Aeroleds nav/strobe/tail lights (all required in Australia)
- no landing lights to be installed

And bits outside of Vans:

- SafeAir1 pitot/AoA/static system
- capacitance fuel senders (unsure of brand at this point)
- Dynon unheated pitot/AoA
- Gretz pitot mount
- Dynon pitch and roll AP servos and mounts for the RV-8

Looking ahead I will need to factor into the build, as I go:

- ELT installation
- ADAHRS mounting
- Pitot mount
- Dynon pitch and roll servos and mounts
- remote magnetometer mounting (if required)
- rear mounted battery

Obviously everything will become much more clear as I start my build but just wondering if there are any glaring omissions/errors in anything above.

I am also considering the Grove Airfoiled landing gear in my quest for lightness.

I have been reading through these forums for awhile now and really appreciate that there is so much valuable information around, thanks everyone!

Tom

[ColoRv]

A few things off the top of my head.

Why alternate static source in day Vfr plane?

Which Garmin GPS and why? For Vfr day only the Dynon should be fine though I would play with and price out all the systems before making that choice...and I would do all of that after the fuselage is done (except forward top skin) and canopy done (not windscreen obviously). In other words put it off until as late as possible. Do NOT pick your avionics yet...that would be like choosing an airplane to build now....Before the wright brothers flew. A lot will change between now and when you make that choice. Chances are the avionics you will use haven't even been conceived of yet. Wait.

Vane and AOA? Do you really want both chirping at you during aerobatics?

Have fun!

[OzStriker]

Hi ColoRv,

Point taken that leaving the avionics till last is best, I can see that leaving a wing skin and the forward fuselage top skin allows this side of things to be decided later on.

Alt static and vane is just me trying to have some redundancy when I can at minimal weight cost but I see your point...

As for mentioning Garmin, I was referring to a Garmin GPS receiver, Dynon receiver is not approved for Mode S transponder position information in Australia (last I heard) but as you have stated, this will be probably be different in a few years time!

Leave the avionics alone for now, understood

[Andy Hill]

Hi Tom

Quick thoughts... take as you wish

- built light and relatively simple for day VFR flight, capable of negative G aerobatics

1. - fuel flop tubes x2 : Suggest just one for simplicity, lightness, has some gauging benefits and fuel useage at low levels
2. - stall warning vane : would not bother - RV-8 has some natural buffet stall warning, and you could land it just by attitude with no IAS
3. - manual aileron trim : consider omitting altogether
4. - ground adjustable pedals : these do save weight (1.5lbs?) but I would avoid if you ever want to adjust them!
5. - capacitance fuel senders : seem to cause more trouble than they are worth? Float senders seem fine.
6. I am also considering the Grove Airfoiled landing gear in my quest for lightness : if you really want light, use the Std Grove, not Airfoil
7. - Christen inverted oil system : or Raven (essentially the same)
8. - rear mounted battery If you really want light and go Lithium, no point putting it in rear - and save another 2lbs of long heavy cable!

Seat Belts not mentioned - I'd offer Crows as a suggestion.

[Mike S]

Tom, welcome to VAF

[OzStriker]

Thanks Andy and thanks Mike S !

[drill_and_buck]

I agree with all the suggestions put forth. In addition I would consider....

1. For a day VFR only ship I would eliminate the D6 backup. Just bring along your Ipad mini. It will have everything you need to get you home.

2. Regarding building for negative G aerobatics. If you have recent sustained negative G experience, and like it, then go for it. If not, I would suggest you spend some time hanging by the straps before making this decision. You can have tons of fun with positive G aerobatic maneuvers in the -8 and save some money, weight and reduce complexity by eliminating the inverted oil system.

3. Build light: Consider a 3 blade Catto prop in lieu of a constant speed setup. This will save considerable weight and reduce your parts count.

4. Day VFR only in OZ. Consider a tinted canopy.

5. Most importantly: Build the plane you want.

Enjoy the journey,
MD

[Richard Connell]

Hi Tom,

As others have said, definately leave anything to do with avionics as late as possible. Ideally last. Things change very quickly.

Don't worry about the TSOd ADSB position source. Not required for VFR in AUS, just IFR. You'll just need mode s as the regs currently stand.

Best of luck.

Richard

[OzStriker]

More good advice.

You are right, no need for a backup screen.

Catto prop...Lighter, simpler, sounds like a brilliant idea.

Will chase up a tinted canopy too.

Cheers!

[Robert Anglin]

Looks like everyone has covered this thread very well. I would second fixed pitch, light prop as that is what we did with a Prince "plus-P". The flop tube, only one as that is what we also did. It get harder to hang in the straps as you get older and no one enjoys it for more than a minute, most just 10-15 ticks of the clock. We put ours in the right tank with a full Mil. stainless lining and guides. That way we can inter a left bank to charge the inboard cell, before rolling over, even if the tank is getting low we would have a good long slug of fuel in the inboard cell. You may wish to put two small air vents at the top two vent hole locations on that first inboard tank rib as well. When you are upside down it slows the fuel bleed out of that chamber into the adjacent one, but still gives you venting when you are upright. Be sure and make yourself a very good counter-weighted trap door for the bottom fuel carry though. If you just cut a couple of round washers of .063 and install them on the back side of that trap-door, it will close much better. If you are wanting to have a PFD and also carry a GPS, you may wish to look at the small 7" Garmin IFIS and just carry an I-pad on a remote bracket. Butt as the others have said, I would hold off on the avionics tell you have the whole bird together as there will be lots of new toys in that field come onto the market between now and then. I am not sure how Johansen did it but it would be nice to think my 8 would tore the out back some day. Good luck you will like the challenge. Yours as always. R.E.A. III #80888