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Old 02-22-2014, 02:53 PM
alwaysoutdoor alwaysoutdoor is offline
Join Date: Feb 2013
Location: Twisp, WA
Posts: 44
Default Will I have a CG issue? catto prop on a light RV-7

I have a question to other RV-7 builders and what their CG ended up being.

On my project (taildragger) I will be putting on an IO360 M1B and kinda want either the 2 blade or 3 blade catto prop. I will be painting the plane just 1 solid color and only installing the MGL extreme mini EFIS/EM and probably a Nexus tablet for GPS on the instrument panel (I'm keeping it super simple and CHEAP!). Do you think I will have a CG issue once I am finished with everything (being tail heavy)? What would you recommend me changing? Should I put on a metal FP Sensenich instead of the catto? Use catto and add a super heavy crush plate? Would putting the lightweight tailwheel on solve much for the extra $105 (only is 1lb lighter)?

I would like some advice on what I should do so I don't have big problems once I bring out the scales- I see myself wanting to use the baggage compartment on long flights. Thanks for the help

p.s. I already have the finish kit so changing to the 320 mount to get weight forward is not an option.
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Old 02-22-2014, 03:40 PM
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RV10inOz RV10inOz is offline
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,135

Most likely you will need to add a weighted crush plate for the prop.

I think Catto sells them???

Many have been here before, I made one for Jamie Lee's RV7, and calculated the mass required.

In my opinion a Hartzel C/S is the go, but it is not cheap.

David Brown

DYNON Authorised Dealer and Installer

The two best investments you can make, by any financial test, an EMS and APS!
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Old 02-22-2014, 05:09 PM
BillL BillL is offline
Join Date: Sep 2007
Location: Central IL
Posts: 4,637

There is a W&B thread for 7's here that can provide you with data. The Cato props seem to have a CG an inch further aft. Plotting the data and comparing your weights should help your understanding. Sorry, I don't have access to the plotted data today.

1st Flight 1-27-18
Phase II 8-3-18
Repairman 11-15-18
Instrument Currency 12-17-18
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Old 02-22-2014, 05:20 PM
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N941WR N941WR is offline
Join Date: Jan 2005
Location: SC
Posts: 11,803

Keep building it as light as you can and don't worry. Once you weigh it, you can add ballast, if you need to.

Remember, it is much easier to add weight to a light plane then remove it from a heavy one.
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
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Old 02-22-2014, 05:57 PM
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rzbill rzbill is offline
Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,548

Would it be worthwhile to talk to Vans about the 320 mount dimensions?
I understand it moves the engine further forward. It might be a way to KEEP it light rather than adding the weighted crush plate
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 750hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'
My RV Construction Page
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Old 02-22-2014, 06:42 PM
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tadsargent tadsargent is offline
Join Date: Jan 2006
Posts: 304

The 7 was not designed for a wooden or composite propeller. Your CG will be aft
And the max baggage will be limited. Additionally with 2 average persons aboard you may not be able to land with minimum fuel on board.
My 7a needed more than a 12 pound landoll ring to help the weight. That's why I put on the metal prop which helped. The solution was the Hartzell constant speed propeller.
Tad Stripes Sargent
GRT HXr Glass
Hartzell's advanced composite propeller
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Old 02-22-2014, 06:51 PM
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Brantel Brantel is online now
Join Date: Mar 2006
Location: Newport, TN
Posts: 7,075

I second Stripes comment.

To get mine in a more useful position was going to require way to much dead weight on the nose.
Brantel (Brian Chesteen),
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Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
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Old 02-22-2014, 07:50 PM
rockwoodrv9 rockwoodrv9 is offline
Join Date: Dec 2011
Location: Meridian ID, Aspen CO
Posts: 2,461

Originally Posted by Brantel View Post
I second Stripes comment.

To get mine in a more useful position was going to require way to much dead weight on the nose.
The weight in the front the same if it is a plate or a CS prop. I understand the CS prop gives performance for the weight, but the nose wheel doesn't know that.

I looking at the same issue with my 9A. I have a O-320D2A and will be putting a Catto prop on it because I like how smooth they are. I may have to put a weight in front to get the baggage capacity I want, but Im ok with that. If I ever want to change to a CS prop, it will be an easy change.
Meridian Idaho
O-320 D2A
Awaiting DAR Inspection
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Old 02-22-2014, 10:46 PM
crabandy crabandy is offline
Join Date: Jan 2010
Location: Ottawa, Ks
Posts: 1,954

My RV7/O-360/3 blade Catto weighed in at 1038 with leather/carpet but only a G3X and a handheld. With my typical combined passenger weight of 350 lbs, I was CG limited to about 60 lbs baggage with min fuel. I added the 12ish lb landoll ring to the flywheel and inow I can use the full 100 lbs baggage.
I'm happy with my choice.
RV 7 300 hours and counting
12/17 donation
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Old 02-22-2014, 10:49 PM
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McFly McFly is offline
Join Date: Sep 2005
Posts: 333
Default will you have an issue? maybe but probably not

I was in the same boat as you, a light and simple RV-7 (1050 pounds).

I used a 10 pound crush plate from Sabre. With the 17 pound Catto, it is 30 plus pounds lighter than a CS setup. I also used a light weight tailwheel, which pushed the CG forward 1/4".

Having said all that, there are some situations that I have to avoid. Flying acro with a passenger over 180 lbs is one (not a problem for me) and empty tanks with a passenger and full baggage. I have found that easy to plan around.

You may have to do some soul searching to see if you can live with those limitations. It has been a non issue for me. Good luck.
Northern California
RV-7 Flying
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