Best Engine for Exp PA-12 on Amphibs?

[skywagon8a]

This:
https://whirlwindpropellers.com/aircraft/product/ga200l-stol/
or this:
https://www.sensenich.com/product-c...y=lycoming-o-320&filter_material=carbon-fiber

 

[stewartb]

Here’s an example of the weight-benefit decision. Why not an MT constant speed reversible? Optimum pitch for every phase, every flight.

 

[Bill Rusk]

Some excellent inputs. I will try to get a couple of weights today.

Bill

 

[Gordon Misch]

Good comments. Thank you!

 

[The Kid]

I think my Sensenich GA , with the cool spinner, weighs 21 and maybe a Catto at 15? I think the whole idea of light is stall speed and "feel". If you can do something to greatly lower the stall speed, but it ads weight, then do it! But then, to me, how does it feel to fly? If it feels OK to you then you haven't had to spend big bucks chasing the weight issue and you're ahead of the game.... One other thing on the prop. A prop that is ideal in the summer, won't perform the same in the winter cause the air is denser and you need less of a bite to pull the same RPM. So, adjustable seems like the way, I guess.

 

[Bill Rusk]

Sensenich ground adjustable for 0-360...

Blade 1 64.81
Blade 2 64.11
Hub with hub bolts (NOT prop bolts) 162.88
Total 292.1 oz. or 18.256 pds

Catto 84-43 with both crush plates 15.5 pds.

I was wrong to say the ground adjustable was 10 pounds heavier. It looks like the Sensenich is 2.75 pounds heavier.

Hope this helps

Bill

 

[Steve Pierce]

Four of the hub bolts double as prop bolts on a Sensenich GA prop. The O-360 hub is probably a little heavier than the O-320 but the blades are the same, different pitch pins when setting up.
Hub and bolts for the O-320 weighs 11 lbs 12 oz. 2 of the prop bolts are within the hub.


Blades that I weighed are 3 lbs 15 oz to 4 lbs 1 oz.


Spinner assembly weighs 1 lb 12 oz.


So total is 21.5 lbs with spinner. I don't run the spinner so 19 lbs.

 

[RaisedByWolves]

I don’t recall the weight of a 320 Catto, but it was exactly half the weight of a 82/ borer. 15/16lbs I think.


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[Steve Pierce]

Borer McCauley 1A175 props I have weighed varied from 33.2 lbs right out of the box to 32.5 for a good one in service.

 

[BES]

I changed the 76" Sensenich 32 lb. prop on my exp. 12 to a 12 lb. Catto. Couldn't be happier with the swap.

 

[algonquin]

I had a whirlwind on a StarDuster and really liked it, wish it was certified, I’d put one on my 12 when I get it done.

 

[hunt/trapak88]

The ga sensnich pulls better than a Catto. Only downfall so far is how long it takes to get one. I thought the weight was pretty close to the Catto.


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I’m late but would love to see these “results”. I’ve never used anything but Cattos from c90 to 360. Suppose i used an 8443 Pawnee for 50 hrs or so other than that catto. So call me
biased a little. All this talk of props and pulling and scouring for real world scale results I’ve only found one time on here where someone posted results of a GA (WW) vs a Catto and it was a 9:1 320. The GA yes did out pull an 8436 catto……by 12lbs with 200 more rpm’s helping it. The absolute flattest setting. 12lbs more aka nothing.

Is it really pulling harder or is the Tac leaning more eastward and the engine making more racket? I dare not say how many cattos of length and pitch I’ve tried. If fixed pitch only other prop I’d run on 360s or better is a 90” Mac. You can’t argue length and chord accompanied by proper pitch. To each their own.

 

[mvivion]

13 rib Piper wings on a 18A was good to 2070 lbs. I would not worry a bit about 2300 lbs Gross weight on Dakota wings. But I tend not to worry that much in general.
DENNY

Denny,
That is true….but only in a very narrow window. That GW was only authorized by Piper for Agricultural (spray) operations, NOT for Normal category ops. Now, take a look at the criteria required under Ag ops back then……. Point is, repeating that old saw is a red herring, unless all you want to do is fly straight, turn left and land empty.

MTV

 

[skywagon8a]

……. Point is, repeating that old saw is a red herring, unless all you want to do is fly straight, turn left and land empty.

MTV

.....in smooth air where most agricultural work is usually done.

 

[DENNY]

Denny,
That is true….but only in a very narrow window. That GW was only authorized by Piper for Agricultural (spray) operations, NOT for Normal category ops. Now, take a look at the criteria required under Ag ops back then……. Point is, repeating that old saw is a red herring, unless all you want to do is fly straight, turn left and land empty.

The point I was trying to make at the time (apparently poorly) was they where not using stock piper wings. Rather stronger Dakota Cub wings so a heavier Gross Weight was appropriate.
DENNY

 

[skywagon8a]

Denny,
That is true….but only in a very narrow window. That GW was only authorized by Piper for Agricultural (spray) operations, NOT for Normal category ops. Now, take a look at the criteria required under Ag ops back then……. Point is, repeating that old saw is a red herring, unless all you want to do is fly straight, turn left and land empty.

The point I was trying to make at the time (apparently poorly) was they where not using stock piper wings. Rather stronger Dakota Cub wings so a heavier Gross Weight was appropriate.
DENNY

DENNY, There is more to determining the maximum gross weight than the strength of the wings. Landing loads is one other. An Ag plane generally lands nearly empty after taking off very heavy and could easily be below the 1750 pounds. A normal Cub could be landing at nearly it's take off weight. Didn't Wip add a tube for landing load increases to get their 2000 lbs? The -18 seaplane is 1760 lbs, 10 pounds more due to a different landing gear.

 

[DENNY]

Yes they did it is that little 45 degree angle tube between the front tube of the rear seat and the lower door frame. https://www.airframesalaska.com/Fuselage-Mod-Wipaire-Increase-p/fm-gw.htm I am sure that really beefed up that fuselage for heavy work.:smile: They are adding HP to the 12 which is another part of the equation for Gross Weight. The thing I would actually question is the fuselage. Is it a stock old one/new EX fuselage/ Old fuselage with proper tubing upgrades and inspection. That may be the weak link.
DENNY

 

[DENNY]

Just throwing gas on the fire because I don't want to finish putting my skis on. One of the reasons I tend to be lenient when it comes to Gross Weight is even the FAA seems to think it don't matter that much in Alaska. https://www.airframesalaska.com/Fuselage-Mod-Wipaire-Increase-p/fm-gw.htm I think one of the contributors used that to fly maybe even a little more weight than the law allows when he was up here. The other point is how many have heard of a stock PA 18 wing failure in flight? Not struts/no flaps or aileron flutter/ no drilled spars/no crazy mods. Just a stock wing, that I would bet most have been flown over Gross Weight. Read Mikes stories about sending them back home over the range with ratchet straps and a high lift jack to hold it together. It all makes for good discussions and thoughts to ponder.
DENNY

 

[skywagon8a]

What is legal and what is done on a regular basis when no one is looking or able to see are two different things. Those stories are best exchanged when face to face with known recipients. This isn't exclusive to Alaska.

 

[stewartb]

I’ve ridden in guide’s Cubs that were well over 2000# and likely didn’t have any GWT increase done. The Cub wing is capable of flying the weight. The engine and tail are more suspect. Those need help at that weight. The topic is a -12. The gross weight increase I’m familiar with required power and tail feathers. Nothing done to the wing.

 

[mvivion]

I've flown Cubs in excess of 2000 pounds, operating as a "Public Aircraft". Doesn't mean it was smart, or safe, even though it was technically "legal". And, there are a few reasons that the Public Aircraft rule has been significantly tightened up, BTW. Based on the experience and knowledge I have NOW, as opposed to way back then, there's no way I'd operate a Cub in excess of LEGAL gross weight today.

My point was arguing that the Cub can safely be flown at the Ag Gross Weight because it was "approved" at that weight for certain operations is a specious argument. And, secondly, the airplane under discussion is a PA-12, NOT a PA-18A.

Back to engines por favor.

MTV

 

[dgapilot]

Landing gear has been the primary limiting factor on both gross weight STC projects I’ve been involved with. Next is controllability and CG range. In both cases, the CG range was not linear in that both the forward and aft limit canted toward center from the prior limit. On my PA-16 project I have 4 tubes in the gear structure that will be upsized.


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[hunt/trapak88]

Appears he already has an engine picked out. In the meantime I’m still waiting on the results of the pencil chorded GA Sensenich out pulling a catto of proper diameter/pitch for low end performance. Heard of a guy who has 0-370 and a catto. Got Sensenich and tried the settings. Took it off and put catto back on. Will use as a spare or sell..he flies the aircraft regularly and I trust his word. BTW unless I’m mistaken two cattos can damn near be had for the price of one Sensenich.

 

[stewartb]

Exp? Why Sensenich? Why not the ground adjustable Whirlwind? That’s displaced Catto on most of the exp Cubs I hear about. What about Sterna? With enough power why not the Whirlwind ground adjustable 3-blade? Or a constant speed Catto?

 

[cubdriver2]

Exp? Why Sensenich? Why not the ground adjustable Whirlwind? That’s displaced Catto on most of the exp Cubs I hear about. What about Sterna? With enough power why not the Whirlwind ground adjustable 3-blade? Or a constant speed Catto?

The non certified Sensenich for 150/160 Cubs I think is $3600 range

Glenn

 

[Steve Pierce]

Appears he already has an engine picked out. In the meantime I’m still waiting on the results of the pencil chorded GA Sensenich out pulling a catto of proper diameter/pitch for low end performance. Heard of a guy who has 0-370 and a catto. Got Sensenich and tried the settings. Took it off and put catto back on. Will use as a spare or sell..he flies the aircraft regularly and I trust his word. BTW unless I’m mistaken two cattos can damn near be had for the price of one Sensenich.

How much is a Catto now? Experimental GA Sensenich is $4230.

I have watched several people pitch the WW and I have pitched a lot of Sensenich GA props. If the performance is the same I would take the Sensenich for this reason.

 

[RaisedByWolves]

How much is a Catto now? Experimental GA Sensenich is $4230.

I have watched several people pitch the WW and I have pitched a lot of Sensenich GA props. If the performance is the same I would take the Sensenich for this reason.

The pins are way way easier than the whirlwind. The hubs and blades look very similar, except the sensenich has the pitch pins.


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[hunt/trapak88]

Oh ok. Wasn’t aware the non certified version was that much cheaper. $3250 I believe. Not sure which WW we are talking about. I know one is heavy, has big fatty blades and is quick to adjust and spendy. The other is lighter, cheaper, takes more time to adjust and blade profile is was “skinnier”. Regardless I suppose I’m not opposed to any of them. For me, I just would like to see a pull test results of beating a catto. I know most don’t want them because of speed or lack of. But I have a hard time believing an 82” prop will outpull a 90”. Strictly low end yank that will still cruise high 80’s.

Sterna 88”. Know a guy, loves it

 

[hunt/trapak88]

These outclimb catto, pull harder than catto, etc etc comments I’m assuming are geared towards the 82 or 84” or less versions that are pitched fairly coarse to give guys the close to 100mph cruise
most are after. Throw an 86-90” on and I’d bet it’s a different story..

 

[skywagon8a]

Not sure which WW we are talking about. I know one is heavy, has big fatty blades and is quick to adjust and spendy. The other is lighter, cheaper, takes more time to adjust and blade profile is was “skinnier”.

The big "fatty" one is the 200G...no longer being produced. The first ones were not spendy. I love mine.