GO-300 gearing ratio

[zero.one.victor]

I was looking at an acquaintance's new Cessna 175,with the geared GO-300 engine. I noticed that the prop looked pretty big,it measured 83.5 inches diameter. Looking at a catalog of props,I see that the correct MacCauley prop is an 84-67. Wow! For seaplane versions,it's a 84-55.
I was wondering if anyone knew what the propeller-speed reduction ratio is for these geared engines. I wanted to figure out what rpm the prop turns. The tach is redlined at 3200.
I'm trying to think out the dynamics involved here--the GO-300 is 175 horse as opposed to our 145,but the geared engine might result in lower prop speed than our >2700,even at the 3200 rpm redline. That way,a bigger diameter prop can be used without the tip speed exceeding supersonic. But the super coarse pitch has me scratching my head. According to the same prop catalog data,the 170/172 180-horse Lycoming fixed-pitch conversions use about a 76-60. I figure the lower prop speed of the geared engine must require/allow the use of the coarse pitch.
????

Eric

[mrpibb]

Eric,
I almost bought a 175 but the availabilty of GO-300 parts concerned me. plus the short tbo 1100 hrs ? concerned me also. I had to price out a prop reduction gear for someone and when I did find one it was very expensive. Wit the geared engine you can swing the larger diameter and pitched prop to get the speed and perfomance. The plane I flew would cruise at 130 mph at 2950. the owner claimed on a good day he could reach 138 mph. The price was right but there was 900 hrs on the mill and even at my cost the overhaul would of exceeded my budget.

On a second note what are you using for your checklist on your ragwing.
The previous owner just had a little card with just some speeds on it, so I would like to make up somthing a little more elaborate. The pilots manual was written for a more simpler time, I was going to get a late model 172 manual and intergrate some of the non model specific info. I would like to see what other Ragwing owners are using.
Thanks

Vic

[zero.one.victor]

Don't worry Vic,I'm not about to convert to a GO-300! I just wanted to get some ideas regarding how propeller speed (rpm) and diameter/pitch relate to each other.
Regarding checklists for ragwings,I assume that you're referring to a takeoff/landing type checklist? I'll email you what I use in my ragwing. It's pretty basic,especially the landing checklist (fuel-both,mixture-rich,carb heat-on,65-70 mph). When flying an unfamiliar (simple) airplane in which there is no checklist,I usually revert to CIGAR & GUMPS.
Some of the home-made preflight/takeoff/landing checklists I've seen look more like a checklist for an annual inspection I try to keep it simple so there's less chance of me ****ing it up.

Eric

[GAHorn]

The GO-300 engine has a .75 gear reduction giving a 2400 prop RPM with the engine turning 3200. This made the 175 the quietest cockpit of all single-engine Cessnas.

[flyguy]

When I purchased my '61 C175 a few years ago it was just a 'spec' buy. The price was right (Cheap and needing TLC and only showing 1400 hrs on the tach!) I had heard the rumors about the "geared" engine having problems but I had in mind an engine upgrade (180 or 210 HP) in the future so I made the deal.

Here four years later and about 500 hours I have a lot more knowledge about this particular bird and it's "bastard"engine. It has a "BIG" diameter prop but at (tach indicated) 3150 rpm the prop was turning 2400 something. This was ascertained by a friend flying with me who had one of those little hand-held tachs. We were in level flight at 4500 msl and were indicationg 135 mph. OAT and corrected altitude gave us 143 true. I have flown this thing at full bore (3250 tach) at 7500 and got 145mph true several times.

BTW I have thought a time or two about yanking that prop and just "Trying it out" on my '52 170B. I really have doubts that the old C145 would be able to turn it and gain any legal numbers. If I was operating on a 5000' airstrip - - - well who knows.

Short (1200 hour recommended) TBO probably did a large part to shorten life span (Years in production) of the engine. But many pilots felt inclined to cruise, as the the 2950 rpm posted by mrpibb shows, below the best engine performance range of this particular mill. This stressing and overheating of cylinders contributed to less than optimal engine life. This caused consumers to shy away from buying this very nice plane and Cessna soon dropped the C175.

[Dave Clark]

I bought a 175 for resale a couple of years ago. It had a constant speed prop. I also resold a 175 a lot of years ago that had the long fixed pitch prop. The constant speed is much better performing.

The 175 is indeed a nice plane with the geared engine and either prop. A very affordable performance plane and if treated right can give some good service.