C of G for O-360 conversions

How to keep the Cessna 170 flying and airworthy.

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daedaluscan
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C of G for O-360 conversions

Post by daedaluscan »

I have just bought an STC to put an 0-360 on my B model.

I am considering props and have been offered an 80” Hartzell with the harmonic balancer. Anyone running that setup who can tell me weight and C of g?

I would actually like to know any 0-360 conversion C of G, fixed pitch or constant speed.

Any input or advice appreciated.
Charlie

1956 170B C-GDRG #27019
swixtt
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Re: C of G for O-360 conversions

Post by swixtt »

Hey Charlie, mine when it was first done...Delair, Hartzell
Weight (lbs) Arm (inches) Moment (lb2s*in)
1426.0 ---------- 37.12---------- 52933.12

i don't have the numbers before conversion at hand.
what STC did you get?
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daedaluscan
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Re: C of G for O-360 conversions

Post by daedaluscan »

Thanks, Delair
Charlie

1956 170B C-GDRG #27019
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DaveF
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Re: C of G for O-360 conversions

Post by DaveF »

1954 170B on normal tires

1393.5, 38.6, 53833

Avcon, MT MTV-15-B/210-58 CS prop. W&B calculated since weighing in 1993.
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ghostflyer
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Re: C of G for O-360 conversions

Post by ghostflyer »

My conversion is a Delair with a weight of Arm of. Moment of
1432 lbs. 37.9ins. 54246
Plus a sensenich fixed pitch prop of 60ins pitch and dia of 76 ins .
My bird will be a lot heavier due to a heap of STC,s fitted. There is a heap of weight on the nose and was tempered to add weight to the rear of the fuselage . Not a smart idea if one does the maths as it will add to the moment arm when approaching a ground loop.
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c170b53
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Re: C of G for O-360 conversions

Post by c170b53 »

This is with a 0-320 c/s Hartzell compact, lightweight starter, battery in the back.
1415 lbs, CG 37.94, 53685
I think we had the discussion somewhere in the past, Lycoming engine is lighter but not by much. Small things add up to make the conversion = to the old install. New fibreglass nose bowl adds weight out front. Alternator is lighter than a gen but sits more forward. Same with the exhaust. If you go C/S add the weight of the governor but really there's not much difference until the prop choice, which I think has the greatest impact on where the C of G lands.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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Kevin Pearce
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Re: C of G for O-360 conversions

Post by Kevin Pearce »

1953 C170B 800 x 6.00 tyres
Avcon 0-360 with 76” Hartzell CS Prop

Empty Wt 1355 lbs
Moment 50258.75
Arm 37.09”

No fuel or oil
Ballast is required in baggage area for some loading cases.
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daedaluscan
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Re: C of G for O-360 conversions

Post by daedaluscan »

Thanks so much for all the replies, pretty consistent around 37". This has really helped with my decision making process.

Better with fixed pitch, best with MT.
Charlie

1956 170B C-GDRG #27019
swixtt
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Re: C of G for O-360 conversions

Post by swixtt »

are you determining CS/non CS or make of prop?
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daedaluscan
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Re: C of G for O-360 conversions

Post by daedaluscan »

CS or not. Id really like to go CS, but I dont want one with the 100hr AD. I have found an 80” Hartzell that does not have it, but it is heavy with the harmonic balancer and Hartzell will only switch th STC to the same type- for $500usd. It is off a 175 and so I cant get the STC swapped.
Charlie

1956 170B C-GDRG #27019
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DaveF
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Re: C of G for O-360 conversions

Post by DaveF »

You should be able to find a serviceable Hartzell HC-C2YK-1BF/7666-2 74” with a B-suffix non-AD hub. Might take a bit of time, but the improved hub has been out for more than ten years, so the props are out there.
Last edited by DaveF on Wed Dec 11, 2019 4:18 am, edited 1 time in total.
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c170b53
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Re: C of G for O-360 conversions

Post by c170b53 »

Go C/S, cool temps off your runway, you’ll see 1600ft/ min. Just those days alone will relieve the sting (AU’s) of a C/S prop. Then on really hot days you’ll easily get off when others may have to wait.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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TFA170
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Re: C of G for O-360 conversions

Post by TFA170 »

Anyone running the new composite trailblazers? Those should be pretty light
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daedaluscan
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Re: C of G for O-360 conversions

Post by daedaluscan »

DaveF wrote:You should be able to find a serviceable Hartzell HC-C2YK-1BF/7666-2 74” with a B-suffix non-AD hub. Might take a bit of time, but the improved hub has been out for more than ten years, so the props are out there.
I think this is the way I am going to go. None of this makes any financial sense so I may as well do the thing right.
Charlie

1956 170B C-GDRG #27019
bat443
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Re: C of G for O-360 conversions

Post by bat443 »

I have a 54 170B with a wide deck O-360A1A Avcon conversion and 80 inch Harzell with the balancer. I would call the performance outstanding and this installation because of the balancer has no rpm range restrictions.

1487.2 pounds at 38.27 weighed about 10 years ago by someone other than me. Has 8.00 tires, double puck Clevelands, factory camera hole aft of pilot seat, baggage door, Javelin fuel tank (24 pounds at 99 inches) com and transponder and an much heavier interior than it needs to be. Flies fine. I plan to lighten up the interior and reweigh the plane myself in the spring.

Dave Stoots ant Stoots Aviation in Fairbanks, AK will sell you an STC to install the 80 in prop on a 180 hp 170 and doesn't care what airplane it came off. A friend on mine ran into the same problem with Harzell when he tried to install a 80 inch off a Husky and was told it was not in the "correct" serial number group to be installed on a 170 and he would need to buy a new prop. He called Stoots and they issued him the STC for $500, it made the installation affordable by being able to buy a used prop.

Tim
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