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Aerobatic Propeller & Full Raven Oil, or just Full Raven?

inktomi

inktomi

Well Known Member
Sponsor
Hello folks!

I'm trying to decide on a propeller for my RV-8. I am trying to make it fit into a 13" spinner (hard..).

I want to use my RV-8 for Sportsman IAC aerobatics, this means some negative G from time to time. I'm including a Full Raven Inverted oil system, and had been planning on also using an aerobatic prop just for complete safety. I've found that it's _really hard_ if not impossible to find a counterweighted prop that will fit a 13" spinner. Whirlwind makes the aerobatic 330 series but that needs a 14" spinner I think.

I was planning on using the James Aircraft cowling which fits a 13" spinner, though they say "with some bodywork" I could make a 14" spinner fit. I'm not sure what that would entail, but I bet it's not easy to make it look like the cowling perfectly fits a 14" spinner. Does anyone know?

Given that there are only short sequences of negative G in the sportsman routine, with the Full Raven Inverted Oil system, would a non-aerobatic prop work?
 
inktomi said:
Hello folks!

I'm trying to decide on a propeller for my RV-8. I am trying to make it fit into a 13" spinner (hard..).

I want to use my RV-8 for Sportsman IAC aerobatics, this means some negative G from time to time. I'm including a Full Raven Inverted oil system, and had been planning on also using an aerobatic prop just for complete safety. I've found that it's _really hard_ if not impossible to find a counterweighted prop that will fit a 13" spinner. Whirlwind makes the aerobatic 330 series but that needs a 14" spinner I think.

I was planning on using the James Aircraft cowling which fits a 13" spinner, though they say "with some bodywork" I could make a 14" spinner fit. I'm not sure what that would entail, but I bet it's not easy to make it look like the cowling perfectly fits a 14" spinner. Does anyone know?

Given that there are only short sequences of negative G in the sportsman routine, with the Full Raven Inverted Oil system, would a non-aerobatic prop work?
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A counterweighted aerobatic prop is unnecessary and is likely heavier. I flew IAC competition for almost three years in my RV-8 up through Intermediate and never had an issue. I have the standard non-blended airfoil prop and a full Christen system. Not sure of the differences between Christen and Raven. Just be sure you pay careful attention to the installation instructions. The locations of the various components is critical. I also have the B&C Vac-2 inverted oil pick up.

What engine do you have? The sump design makes a difference. I do have to maintain my oil level higher than most. I have the angle valve IO-360A1A. The sump is designed such that the upright oil pickup is installed on a welded boss on the rear of the sump. The pickup extends forward toward the middle of the sump, but doesn’t quite reach the middle. During steep descents at a constant speed or rapid deceleration, the oil sloshes forward potentially un-porting the pickup. I have to maintain at least 6.5 quarts to prevent this from happening in those conditions. I learned this during phase 1. It has never occurred during practice or competition with the oil level above 6.5 quarts.
 
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By the way, I know of at least four other RV’s that competed (two others through Intermediate) and none had a counterweighted aerobatic prop.
 
That sounds hopeful. I was thinking since I'm new to aerobatics - of course, I'll do a course - but as a beginner I thought the counterweighted prop would give me an extra margin of safety.

I am building my AEIO-375 -M1S at Aero Sport this summer, and they'll hook up the full raven system with me there.
 
In theory with the Raven system never exposing the oil pickup tube to air, why would you also need an accumulator to maintain pressure?
 
Even with a Christen inverted system oil pressure fluctuates a lot during aerobatics, especially during transition from positive to negative and back. Various on-the-knife-edge positions (even transient) could also give you a headache. In generally, some kind of an overspeed protection is considered to be a must for more or less serious aerobatics, and I agree, some people may get away without one if careful enough. Also, many fixed pitch aerobatic and racing pilots don't really care about occasional overspeeding, too.
 
I’ve got a WW330-2B counterweighted, inverted Christen system and flop tube on the left tank of my RV-8. Getting ready to do IAC Comp myself with it. The whirlwind was lighter by about 12lbs compared to the hartzell. (Hartzell was non-counterweighted) helped with the weight and balance but I also did an earthx to get rid of the rg25xc. Overall the plane lost 48lbs (1105 to 1057 empty) of weight with losing the vacuum system, new prop, the battery and losing a lead weight out of the tail. I do find it still to be nose heavy for spins and plan on putting a weight in the tail again to help with the CG for aerobatics only. I like my combination, my friends like it and find it balanced well. That whirlwind pulls hard!
 
inktomi said:
In theory with the Raven system never exposing the oil pickup tube to air, why would you also need an accumulator to maintain pressure?
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None of the aforementioned RV’s had accumulators or any special over speed protection. Just ensure you keep the oil at an appropriate level.
 
inktomi said:
In theory with the Raven system never exposing the oil pickup tube to air, why would you also need an accumulator to maintain pressure?
Click to expand...

Go back and read what Jerry wrote. You can expose the oil pickup to air. The maneuver needed to do so depends on the sump installed. Jerry has an angle valve with the pickup in the rear, so a lot of nose down can un-port his if the oil level is low. I recall another fella here who suffered an overspeed just that way.

I recently installed a full Raven on an updraft sump. The pickup screws into the right sump drain, so a left knife edge would likely have it sucking air. It's not a big deal. Put the flop tube in the left fuel tank, and only do knife edge to the right.

inktomi said:
I was planning on using the James Aircraft cowling which fits a 13" spinner, though they say "with some bodywork" I could make a 14" spinner fit. I'm not sure what that would entail, but I bet it's not easy to make it look like the cowling perfectly fits a 14" spinner. Does anyone know?
Click to expand...

Easy is a relative term. It's straightforward glass work requiring only hours or Benjamins. I did one more than 20 years ago.

BTW, Showplanes has an -8 cowl for a 15" spinner.
 
Thank you everyone for the feedback! I think I'll be happiest with a counterweighted prop, it's just one less thing to ever worry about. Thank you for sharing the photos of your cowlings using 14" props. I'll do the same.

I have time, and if not I can hopefully find someone to help me, and so long as it doesn't end up looking like a giant spinner is attached to a tiny little cowling I'll be happy. Just need to smooth that intersection one way or another. I don't like that the Showplanes cowl doesn't have a separate intake for air - I know, it's a style thing, but the James Cowling (and even Van's) method of not sharing a cooling intake just seems a lot nicer to me.
 
To close the loop, I'm going use the counterweighted 330 whirlwind prop which uses a 14" spinner.

I spoke with James of James Aircraft this morning about this as well, and he walked me through the changes to use a 14" spinner on his cowlings - normally they'd use a 13" spinner.

He's including the front end of his RV-10 cowling in my RV-8 order, and the -10 uses a 14" spinner. So the work for me is to overlay the -10 front end on my cowling and bond it using a few strips of fiberglass. He said I could even just overlay it and not need to cut any of the -8 cowling off, but we'll see how it actually fits.
 
Gabe214 said:
I have a hankering to go into a Giles 202 and wondered if the 330 3B would be a better performer than the MT’s that are typically on them.
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I have a -200 and recently replace a 2-blade mt with 3-blade WV 330 series and I think WV is better than MT. I also heard a lot of good things about the original 2-blade WV -AC200 aerobatics prop, but they do not make them any more.
 
inktomi said:
He's including the front end of his RV-10 cowling in my RV-8 order, and the -10 uses a 14" spinner. So the work for me is to overlay the -10 front end on my cowling and bond it using a few strips of fiberglass.
Click to expand...

Probably want more than a few strips of glass.

Cowls are under more pressure than most folks realize. A stock -8 top cowl will be pressurized to nearly 110 lbs per square foot above the engine when down on the deck at VNE. Three square feet is 330 lbs, four is 440. It's why RV cowls push up at the firewall attach joint, and the old polyester -4 cowls crack around the spinner area.

Anyway, bond that extra glass like you would be willing to hang the upper cowl inverted by the edges and jump up and down inside it. If the new joint flexes, it won't look good in a few years.
 
DanH said:
Probably want more than a few strips of glass.

Cowls are under more pressure than most folks realize. A stock -8 top cowl will be pressurized to nearly 110 lbs per square foot above the engine when down on the deck at VNE. Three square feet is 330 lbs, four is 440. It's why RV cowls push up at the firewall attach joint, and the old polyester -4 cowls crack around the spinner area.

Anyway, bond that extra glass like you would be willing to hang the upper cowl inverted by the edges and jump up and down inside it. If the new joint flexes, it won't look good in a few years.
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I really appreciate it!! I know this isn't the forum for composite work, but I'm for sure all ears on the best way to bond the two. Once I get it all I'll post a thread in the proper place to gather feedback and info. I want it safe, strong, and lasting that way for many many years.

One addition - he did tell me that there was no need to _cut off the front of the RV-8 cowling_ - I could overlay the two. That's probably the stronger way to do it I'd think.
 
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