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  #1  
Old 04-15-2021, 09:41 PM
dodgeram2500 dodgeram2500 is offline
 
Join Date: Oct 2018
Location: Ontario, Canada
Posts: 11
Default New 8 "Big Build" Planning

G'day RV specialists.

I have ordered an 8 empennage, completed the toolbox kit (even ordered a second one, lol), and am currently setting up my hangar for the "Big Build." I'm built like an offensive lineman at 6' 290bs and 42" waist. Shoulder room is important for this build, and so are c of g considerations. My mission is to have a VFR time machine that is fun and includes the odd aileron roll. I thought about the -14 but meh....I want tandem seating and efficiency.

Here is where I'm not flexing:

Priming - Nope. Not doing it. I want to keep the airplane as light as possible and I don't feel priming is worth the extra time investment. My 1969 Cherokee isn't primed, has sat outside a lot and is truckin' along just fine. I'll prime the non alclad stuff.

Showplanes Fastback - This is a must for a "big build." Extra shoulder room, better vis, less drafty for the ol' lady, done and done.

Prop - Fixed pitch due to cost and simplicity. I am undecided on metal vs composite ground adjustable however. I know that composite is much (20ish lbs) lighter but I also know that where the weight is is important. In the rv8 the pilot sits aft of the CofG...maybe a heavy prop would be a good way to balance this aircraft out?

Battery - Up front in my case!

Where I need your help:

Engine choice - I'm torn between a 175hp IO-340 and a 180hp IO 360. I want to run 91 mogas so 8.5:1 is my comfortable compression limit. I understand that the 340 uses a 320 mount which is further forward than that of a 360. With all else equal will a light 320 installation have the same W/B moment arm as a 360 installation because of the difference in engine mount length? I'm leaning towards a 360 due to it's availability...I can piece one together from a core or buy a kit engine. The 340 is a little more of a one off, and probably less durable. Thoughts?

Landing gear - I see that grove isn't listing landing gear on their site anymore... Maybe the heavy steel gear is better in my case? Is the sky designs gear tougher than stock or just lighter? I'm trying to decide if its worth the $$$

Anything else you can think of? How would you set up a "big 8" build?
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  #2  
Old 04-16-2021, 07:47 AM
Sky Designs's Avatar
Sky Designs Sky Designs is offline
 
Join Date: Dec 2018
Location: Anacortes, Washington
Posts: 20
Default Gear legs & engine mounts

FWIW: There is only one version of the engine mount for RV-8 – it is the same length mount for O-320, O-360, or IO-390. Knowing that you’d like to retain the ability to run mogas, my very much non-expert suggestion is that you go with an O-360 as it is such a “known quantity” engine.

As for landing gear, the Sky Designs leg is fundamentally the same strength as the Grove leg. The difference is that our design uses an airfoil section which, IMHO, looks prettier ;-)
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  #3  
Old 04-16-2021, 09:49 AM
PhatRV PhatRV is online now
 
Join Date: Mar 2018
Location: Buena Park, California
Posts: 434
Default

The IO360M1B engine that you get through Vans is certified for non 100LL gas. I think all lycoming parallel valve engines are the same, except for the aerobatic.
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RV8 standard build: Empennage 99% completed
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Avionics Installation -- 90%
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  #4  
Old 04-18-2021, 05:59 AM
N82VM N82VM is offline
 
Join Date: May 2017
Location: Warrenton, VA
Posts: 44
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Here’s a thread. This guy built a basic VFR machine under 1000 empty weight. 972lbs.
https://vansairforce.net/community/s...d.php?t=109916
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  #5  
Old 04-18-2021, 04:09 PM
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Don Patrick Don Patrick is offline
 
Join Date: Feb 2010
Location: GTA, Ontario
Posts: 856
Default Sizing

Hey Pat,

Where are you located?

I’m in Oshawa...if you haven’t sat in a 8, your more than welcome to come and sit in mine. I’m 5’9, 175 lbs and the 8 fits like a glove....

Don
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  #6  
Old 04-19-2021, 08:11 PM
dodgeram2500 dodgeram2500 is offline
 
Join Date: Oct 2018
Location: Ontario, Canada
Posts: 11
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Thanks Don!

I might have to take you up on your offer! Home base for me is CYCC Cornwall, but I'm in the 'shwa every once and a while. My dad lives in Scarborough so it's on the way!
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  #7  
Old 04-20-2021, 05:43 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
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Default

Quote:
Originally Posted by dodgeram2500 View Post
In the rv8 the pilot sits aft of the CofG...maybe a heavy prop would be a good way to balance this aircraft out?
Pilot weight is not a big factor here, as the CG shift between a 175 lb pilot and a 300 lb pilot is only one inch. The CG wild card for an 8 is passenger and baggage, here potentially exacerbated by the fastback's larger aft volume.

Quote:
Anything else you can think of? How would you set up a "big 8" build?
I'm well over 6' with long legs and big feet. I eliminated the forward baggage well to ensure it didn't contact my right calf. The "ground adjustable" (i.e. fixed) rudder pedals offer a clear floor so it's possible to shift leg position during a long flight, as well as extending the feet through the pedals to the firewall. A seatback cushion built of temperfoam can be quite thin.
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  #8  
Old 04-20-2021, 10:23 AM
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Tall_Order Tall_Order is offline
 
Join Date: May 2020
Location: Alberta, Canada
Posts: 8
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Quote:
Originally Posted by DanH View Post
The "ground adjustable" (i.e. fixed) rudder pedals offer a clear floor so it's possible to shift leg position during a long flight, as well as extending the feet through the pedals to the firewall. .
DanH, do you mean the ground adjustable pedals are wider apart and that you can stretch to fit your feet/legs between them?

I chose some options "sight unseen" but opted for the inflight adjustable, but would seriously consider giving that feature up if it grants this kind of space instead... (I've flown other airplanes both with and without this space)
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  #9  
Old 04-20-2021, 11:35 AM
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rv8bldr rv8bldr is offline
 
Join Date: Jan 2005
Location: Pakenham, Ontario, Canada
Posts: 596
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I'm 6'3" and over 300. I built my -8 without the lower part of the front baggage compartment like Don, had an angle valve IO-360, Catto prop, and the battery aft of the rear baggage compartment. My CG was just fine and I had lots of room.

Google C-GURV. It's now owned by a couple of buddies of mine in my EAA chapter.
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  #10  
Old 04-20-2021, 03:21 PM
sjhurlbut sjhurlbut is offline
 
Join Date: Jan 2005
Posts: 870
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Heres my 2 cents.

Priming - yeah sure alclad is good on its own. HOWEVER in Canada you'll have to prime. Right in the inspection document it says are all surfaces protected for corrosion - sorry Alclad doesn't count. Just get some self etching grey primer and give it a quick spray.

Showplanes - rocks - easy choice

Prop - put fixed pitch on my last 8. Liked the prop but thought performance would be better. I'd consider CS if I were you. I like Whirlwind.

Battery - use EarthX. Doesn't matter where it goes. Mine was behind baggage wall.

Engine choice - I'd stick with 180hp IO 360 variants if you ever think you'll sell the airplane.

Landing gear - I had grove on mine - totally worth it. They are still sold here:
www.skydesigns.aero

Else?
Good discussion on ground versus flight adjustable pedals. Ground will give you more room and prob easier smarter if no one else flying your airplane.

Consider a bent stick instead of the stock one. I personally didn't mind it but it ends up quite low to clear panel and bulkhead behind panel.

Contact me directly if you have any other questions.
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