What are the consequences of a shorter or longer spinner cone?

[kicktireslightfires]

Does anyone know what the consequences of going with a shorter or longer spinner cone than the one that came with the plane would have? I would assume the length of the spinner was a conscious choice by the manufacturer that goes beyond looks? A prop manufacturer is telling me that switching from a 16 inch long spinner to a 13 inch long spinner will have absolutely no consequences. I just want to verify that. Not looking for guesses though; does anyone know matter of factly? Thanks in advance!

 

[murphey]

Does changing the spinner cone require a 337? If so, will the prop manufacturer pay for the paperwork and anything else needed or will you? IMHO, their idea, they pay.

 

[Magman]

OP is EXP.

 

[murphey]

OP is EXP.

So? Just because it’s exp doesn’t mean the designers arbitrarity picked 16 inch. Had to be a reason.

 

[Magman]

OP aircraft is Experimental and as such no 337 is required.

My WAG is that at least some of this is dictated by the Sales Staff.

The C150 had about 4 or 5 choices during it‘s production run.

Some were better than others.

Some aircraft have Spinners listed as Required Equipment on the

TCDS so there is likely some technical reasons for the item.

The first Mo-gas STC was issued for a Cessna 150.

One of the original requirements was the aircraft must have a

Spinner. I believe this was changed changed quickly.

The concern may have been with cooling.

Spinners can be pricey to purchase and maintain.

Lack of the latter can result in their “ explosion”.

That gets ugly.

 

[keen9]

What airplane. Generally, for slower airplanes it isn't going to make much difference at all and so the shape may be as much for appearance as anything else. As you go to faster airplanes it'll matter more. The flow into the engine cooling inlets and engine intake inlet are most affected. The dynamics on the prop could also be affected.

 

[Daleandee]

My uneducated, homebuilder airplane experience, would suggest that cooling would be high on the list for reasons requiring a certain spinner. Don't know if the weight involved is enough to affect CG (likely not).

Some longer spinners require both a front and rear bulkhead where some shorter ones do not. I like fiberglass spinners as metal spinners tend to crack more but I've known fiberglass spinners to disintegrate also.

Lastly ... looks count too! Don't buy no ugly spinner!

 

[FORANE]

My uneducated, homebuilder airplane experience, would suggest that cooling would be high on the list for reasons requiring a certain spinner. Don't know if the weight involved is enough to affect CG (likely not).

Some longer spinners require both a front and rear bulkhead where some shorter ones do not. I like fiberglass spinners as metal spinners tend to crack more but I've known fiberglass spinners to disintegrate also.

Lastly ... looks count too! Don't buy no ugly spinner!

I've heard cooling is a concern, but in my experience with or without a spinner didn't seem to make a difference. Completely agree with metal spinners cracking; I would avoid those. There is a guy on the Lancair forum who makes beautiful carbon fiber spinners.

 

[Stewartb]

Cooling airflow is less disturbed with a spinner and better again with a more streamlined spinner. My Whirl Wind prop’s blades have exaggerated twist near the hub. It’s known to promote cooling. It uses a 14”+ spinner. The Cessna has a 15 1/2” spinner.

 

[kyleb]

Longer spinner cone = more potential runout and vibration. Be aware...

 

[Daleandee]

On the experimental Sonex aircraft with Corvair conversions different spinners are used. At the prop hub area (using a wooden Sensenich prop) the air flow is altered by the blade roots. The air flow is better managed if the roots are covered by a larger spinner that causes less interruption of cooling air into the plenum area above the engine. My airplane uses a 13" fiberglass spinner from Van's aircraft. Notice the difference in the factory spinner (top photo) and the aftermarket larger spinner:

 

[Greg Bockelman]

Notice the difference in the factory spinner (top photo) and the aftermarket larger spinner:

I also noticed the redesigned cowl openings. Looks nicer and I am sure it improves cooling. I don’t think that spinner would have helped much with the original cowl.

 

[Daleandee]

I also noticed the redesigned cowl openings. Looks nicer and I am sure it improves cooling. I don’t think that spinner would have helped much with the original cowl.

The cowling and spinner (in the bottom photo) were the ones designed for a Corvair FWF package by Dan Weseman of Sport Performance Aviation. The plane with the small spinner was a builder that adapted the factory cowling to a Corvair engine. From all I know and have learned, Dan's spinner & set up cool much better & look much better too. Sonex is not a real pretty airplane so we do all we can to help them out ...

My last Sonex had the factory cowl with the smaller spinner on a VW engine. That one had cooling issues but VW engines in Sonex aircraft have a reputation for running high CHTs. I've often wondered if a better cowl and spinner would help with that. I've known a couple of Jabiru 3300 Sonex owners that used Dan's cowling/spinner set up and it improved their engine cooling. But there's no way to claim any absolutes without some serious testing on the various engines, cowlings, plenums, and props.

 

[GeorgeC]

What airplane. Generally, for slower airplanes it isn't going to make much difference at all and so the shape may be as much for appearance as anything else. As you go to faster airplanes it'll matter more. The flow into the engine cooling inlets and engine intake inlet are most affected. The dynamics on the prop could also be affected.

150s are not fast, but @Dan Thomas recently pointed out that spinner choice affects cooling for them:

1965 C-150 Pre-Buy Result

Plane went through pre-buy with the following being reported. Plane just came out of Annual last month. If you got a report like this how would you have interpreted it? Im no longer pursuing the plane as a result. Going off past experience P

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