McCauley Props

If I remember correctly Van's has over 4,000 RV now flying. Is anyone using a McCauley Prop ?

I have been flying McCauley props since 1972 and they have been perfect and always make it to TBO without fail.

I will need a prop for my RV-6A soon and I was shocked at the large amount of AD's on Hartzell and almost none on McCauley over the past 20 years.

Regards
Mike Stephenson

Photoadjuster,

I have a McCauley prop from a Mooney 201 on my RV6, that now has a total of 46 hrs on it (just got my RV6 flying in July of '04). This prop is the one that has the 2 large paddle looking type blades on it, and appears to be working quite well on my 0-360 powered RV6. The original diameter is 74" as used on the Mooney, but mine has been cut down to 72" diameter (73" is all that is legal to cut it down to for use on a certified Mooney, so when I found one that had been in a ground strike while taxiing I was able to get mine for an extremely low cost because it had already been cut to the minimum and couldn't be repaired without being cut down below that size ($1200 originally with an $800 rebuild cost back about 6 years ago). I turn it up to 2850 RPM on takeoff and am getting about 3000 ft/min climb rate, which is very good for an 0-360 powered RV6. At 8000 ft it cruises at 212 mph (GPS ground speed) at 23" MAP & 2300 RPM. It would appear that I have maxed out the prop pitch at that speed, because I can't get any lower than 2300 RPM at max throttle at that altitude. My prop shop says that there is a small ring spacer that they can remove that will allow me to get about 2-3 degrees more pitch if I want it, which would enable me to pull the RPM down lower to around 2200 RPM & 23" MAP so that I can maximize my fuel economy. I'm sure the cruise speed will drop slightly, but so will my fuel consumption (I figure I can still get at least 205-208 mph with a fuel burn of only 8.5 GPH netting slightly better than 24 mpg at that speed...pretty respectable for an RV6 to be sure!!).

While you are correct that the McCauley props seem to be resistant to AD's unlike the Hartzell's (this is due in part to the much more massive bearing size that the McCauley hub has and the fact that is is manufactured as a one piece hub), there are however a few disadvantages in using it.

First of all is the fact that it is VERY difficult to get a spinner backplate to fit up to it. This is due to the hub having no provision to mount a backplate to it. The Hartzell prop is a split hub design, so it enables one to mount a backplate to the bolts that hold the hub together...not so for the McCauley. It requires a set of two plates to be attached to the hub via the hub mounting bolts (which are really studs that are screwed into castlelated nuts that are slid into cutouts machined into the side of the hub and that are threadlocked in order to create a bolt), and these two plates have six holes each in them (for a total of 12 holes) on a 6 5/8" bolt circle that the backplate has to attach to. Normally almost ALL McCauley props utilize a backplate that is mounted to the holes on the ring gear on Lycoming engine installations (which isn't possible to do on tightly cowled planes like the RV's), but there is one McCauley installation on a Cessna that uses the two plates that I mentioned above, so at least the plates are available from most prop shops. Still, there is NO available spinner backplate available from Van's, so you will have to make a custom one on your own out of carbon fiber. There is one other guy here in the US that did just that for an ACI installation in his RV8 (ACI uses the McCauley hub for their composite blade upgrade), and he made up a few extra backplates when he made his mould which turned out to work for me with some modification to the cowling on my RV6. If you go with a McCauley prop I recommend that you try to use the same backplate he makes (I can give you his name & number if you decide to go this route) since it will save you a ton of time & expense making your own mould. I also have an old style long RV6 cowling, so I had to have a 1 5/8" long custom prop spacer made to extend the McCauley hub out, but I still had to trim the face of the cowling back 1/4" to get a reasonable 1/4" gap between the back of the backplate (which I cut as short as possible) & the cowling. Unfortunately in order to get a backplate to work on any McCauley prop on a Lycoming engine you have to be able to pull it back up against the ring gear so that you can get a wrench on the prop bolts, and this means that the backplate can't be too long or you won't be able to get a wrench to fit in. This dictates that you either use a Mcauley extended hub design model 220(they are 6 1/2" long from hub mounting surface to blade centerline), or do like I did and make a custom spacer for use with the standard hub (such as is used on the Mooney prop that I have) that is 4 1/2" long. This also means that you can only make this setup work on a long type cowling, and NOT the shorter cowling that is all that Van's makes now. While the 2" shorter standard hub would seem to be a good fit with the shorter cowling, the backplate mounting plates will end up too close to the ring gear to allow the backplate to be slid back far enough to get access to the prop bolts with a wrench, so you won't be able to install the prop on the Lycoming engine. There is NO easy solution here that I can see other than the method I used. By the way, the aftermarket Sam James cowlings are longer just like Van's older long type cowling, so that is a good way to go if you want to use a McCauley prop, and want the supposed cooling drag reduction gain that they advertise (personally I doubt that they gain all that much to warrant the added cost they are, but then the quality of them is much better and may be the only choice for early RV6's that need a new cowling).

The second problem with alot of the McCauley props (and this includes my Mooney 201 version) is that it experiences a very rough reasonant vibration range that limits its use below 10" MAP when between 1500-1900 RPM which makes landing the RV6 tough without bringing it in with a bit of power, or at idle (keep in mind that all of these McCauley props MUST be used with a counterweighted Lycoming engine because of this). Pulling the engine back in that range is normally what most RV'ers do for an approach, but unfortuanately that only occurs below 10" of MAP when in minimum pitch so it makes landing kind of trickey (I am still trying to work out the best solution for landing approaches at this time). Even the Mooney's are placarded to avoid that range for operation, so it is obviously a function of the prop itself that is peculiar only to a McCauley.

I will say one thing though, the paddle bladed Mooney 201 McCauley prop sure looks MEAN on an RV6, and there is NO other prop that looks as good on the ground!!!!! Otherwise the McCauley props are great props, and FAR better & stronger than any of the Hartzell props (that is why ACI & Whirlwind uses the McCauley hub for their composite blade upgrades on aerobatic versions).

Thanks

tloff,

Thanks for your time to pass on your experience. This is what makes the RV folks the best of the best.

By the way, what is your name?

Regards,
Mike Stephenson

My name is Travis Loofbourrow, thus the TLoof handle!

By the way, the standard McCauley hub is 4 1/2" long from mounting face to blade centerline, and that is what I was refering to earlier when I mentioned the option of using the standard hub with a custom prop spacer. I used a custom made spacer that was 1 5/8" long on my installation, but when combined with the spinner backplate that the other guy had made for his RV8 that I used, I ended up being 1/4" too short with Van's long cowling. This would indicate that I really needed a 1 7/8" prop spacer to avoid any cowling modifications and since I did trim about 1/8" off the back of the backplate flange that the spinner attaches to then a 2" long spacer would have actually been the more correct length. Interestingly enough, the model 220 extended hub that McCauley makes is 6 1/2" long from hub mounting face to blade centerline, which is exactly the same length as the standard hub with 2" spacer...so in otherwords, the model 220 extended hub is the ideal McCauley hub to use on a long cowling RV6. Not only that, but the extended hub that McCauley makes comes with the backplate flange already machined into the hub, so no plates are required for it. I'm not sure why McCauley wasn't consistent with the 6 5/8" bolt circle that is drilled into the plates that can be used on the standard hub, but on the extended hub backplate mounting flange the bolt pattern is 6 1/2" (there is still 12 holes in it just like the plates though). I had the guy that made the backplate drill both sets of holes on both bolt hole centerlines so that I could use it on any McCauley hub if desired. The only thing I don't like about the extended hub in comparison to my custom spacer is that the hub is reduced down in diameter and probably isn't nearly as strong for aerobatics as my spacer setup is. I made my custom prop spacer the same diameter as the crankshaft flange which is about 2 1/2" larger in diameter...combined with being 3/8" shorter in length, I believe the max capable G rating will be increased to around 5.5 G's versus 4.0 G's that the extended hub is limited to (the extended hub Hartzell's are limited even more to only 3.8 G's). Obviously the standard hub McCauley would be even better for high G aerobatics since it is 2" shorter than the extended hub, but the short cowling would be necessary for that hub without spacer, and thus it would be virtually impossible to bolt-up with a backplate on it unless some sort of two piece split backplate were to be made (which would be a bit difficult to install in a perfectly centered fashion in my opinion...but then again that might not be such a bad idea afterall, and if the ring gear were to be used to mount the backplate up to in the process, would eliminate the need for the two plates sandwitched between the prop bolts and the hub! Hmm).

One other recommendation is to use a Cessna front slip-on plastic cone for the front spinner support member. They slide right over the McCauley's front cone, and have the exact same angle as Van's RV6 spinner. The beauty of this little item is that NO holes have to be drilled thru the spinner to attach it like is required on the frontplate of Hartzell props. It centers the spinner perfectly when the spinner is mounted onto the rear backplate, and can be spaced out slightly with cardboard spacers if needed in order to press up more tightly against the spinner cone. This little fellow saves alot of time & effort installing the spinner on the McCauley prop, and works perfectly (most prop shops have used ones available).

Hope this gives more insight to the use of a McCauley prop!

Mooney 201 prop

I just finished installing the same prop on my IO-360 RV-8, the paddle blade short hub from a 201. Mine came with a spinner and backplate, although I am not sure of its origin. The backplate I have sandwiches between the hub and ring gear, puts the spinner/cowl intersection about 3/4" forward of the starter ring gear, and has just enough room to get a wrench on the prop bolts. The biggest problem I had was this setup pushes the whole cowl back an inch/inch and a half or so more than a Hartzell setup, which makes things pretty tight in the nose area. I had to put in a blister for the alternator and fabricate my own air intake snorkel, but other than that it came together OK and looks pretty tough with that prop on it. Reminds me of a Yak prop. Haven't flown yet but will be in the air pretty soon.

Mooney 201 Prop

The backplate you describe that came with your Mooney 201 prop that sandwiches between the ring gear & hub sounds like exactly what is installed on the Mooney 201 from the factory (they come with an aluminum backplate & spinner). I received the same thing with the Mooney prop I bought too, but decided that it just wasn't usable on the long RV6 cowling (not only that, but the Mooney spinner is much longer & heavier than Van's RV6 spinner, doesn't have the same taper angle to match the RV6 cowling, and doesn't look nearly as good on an RV6/7 in my opinion). The backplate design that is used on the Mooney is a short ring close to nearly the same diameter as the back of the spinner, and just barely enables one to get a wrench in to tighten the prop bolts. If it were any longer than it is then it would NOT be possible to access the prop bolts with a wrench! Now the back of the Mooney spinner itself is very close to the same diameter as the RV6 spinner, but it doesn't have the same taper angle (the back of the spinner appears to pointing straight back at the mounting point), but it might be possible to tweak the Mooney backplate slightly to match the same taper angle that Van's spinner has in order to use Van's spinner in such as installation. Unfortunately, using the Mooney backplate is not really a good way to go on ANY RV6/7/8/9 due to the required cowling mods that are required like you experienced. The extended hub model 220 that McCauley makes combined with the Mooney 201 blades would be the better way to go since it would eliminate any cowling mods. That hub is 2" longer (6 1/2" vs 4 1/2") than the standard hub, but it is unfortunately a lower 4.2 G rated hub than the standard one which is good for 6+ G's. If your RV8 cowling only required shortening 1" and not 1 1/2", then using a 1" long custom prop spacer might be a better way to go on an RV8 along with a custom spinner backplate similar to the one I have on my RV6. On the otherhand if it was 1 1/2" that you actually had to shorten it by, then the extended hub is best to use (the same as what a long style RV6 cowling needs... but the short style RV6 cowling is 1 3/4" shorter than the old long style cowling, so maybe they can get away with using a standard hub McCauley with a minor 1/4" shortening on the front of the cowling like I had to do on mine when I used a 1 5/8" long prop spacer with the long cowling). Choices, choices...

Unfortunately, using a McCauley prop just isn't as easy to do as the Hartzell prop due to the backplate mounting problems and length (the Hartzell standard hub is slighty longer than the McCauley standard hub by about 3/8" as I recall). The McCauley hub is FAR superior to the Hartzell hub though, so may well be worth the effort to get it to fit up to the RV (not to mention the paddle blades just plain look MEAN on an RV!!!!!).

McCauley Prop

Travis,

The challenges you describe are accurate. I also mounted a McCauley prop (now with Whirl Wind blades) which came off a 201. I was not willing to use a McCauley spinner for the reasons you describe. They just don't look right. I did purchase a Cessna 210 spinner back plate at a rather steep price. This back plate has a forward sweep that allows easy access to the prop bolts. The rear of the back plate is still further aft than the standard Hartzel back plate. However, it did allow me to use Van's spinner. In order for all of this to work I had to make three modifications. 1. The cowl is mounted further aft to accomodate the spinner back plate. Since I installed my cowl around this spinner, I don't know how much further aft the cowl actually is compared to a Hartzel installation. It did require some rework around the aft cowl hinges and it also required minor modifications to the front baffle ramps. I also had to relieve the honecomb portion of the cowl that interferred with the alternator pully. I simply removed the honeycomb from the inside and reglassed. The net difference in thickness provided enough clearance. A cowl bump, although I didn't need one, would be an alternative. 2. The slope of Van's spinner and the 210 back plate flange angle are not the same. I simply filled the gap with flox and resin. The number 10 screws with tinnerman washers still seat flat. 3. I was not aware of the plastic front bulkhead insert you described. I'm not sure if it would work with Van's spinner but it sure sounds like a great solution. I fabricated out of fiberglass a front bulhead cut to fit tightly around the prop hub. Once the spinner was mounted and aligned propery I permanently fiberglassed this front bulkhead onto the spinner. None of these modifications were too big a challenge. But it is clearly more work and effort than if you just stick with the Hartzel prop in the first place. In my case, I couldn't refuse the deal I got on the engine and the prop. My -8 is flying and I have had no problems with any of these modifications.

Rick McBride

"mean" RV

Any chance of posting a picture of your RV with the McCauley prop? I'd like to see it.

Thanks.

McCauley Prop

I'd be happy to post some photos. Please give me a few days to get some pics.

Rick McBride

McCauley Prop

I have some pictures of my RV6 that has a McCauley prop from off a Mooney 201 on it, but I can't seem to get them to attach to this post. The size of the file for one picture is larger than what the browser will allow to be attached. Can anyone tell me how to go about attaching these pictures?

posting pictures ...

Travis,
You can't post pictures to this forum. However, what you can do is insert a link to a picture that is hosted/posted/loaded on another site. I use ImageShack (http://www.imageshack.ws) which is free when uploading pictures one at a time. I think it costs a penny a picture to upload multiple pictures at once...but haven't went that route.

Hope this helps.

Best,

-Jim
o=\o

I have some pictures of my RV6 that has a McCauley prop from off a Mooney 201 on it, but I can't seem to get them to attach to this post. The size of the file for one picture is larger than what the browser will allow to be attached. Can anyone tell me how to go about attaching these pictures?

Click to expand...

Travis,
Check out Doug's new article on this subject in the "Articles" section of the main page. I'd like to see your pics, too.

Best,

McCauley Prop

After reviewing Dougs article for posting pictures, here's pictures of my RV6 with the McCauley Prop off a Mooney 201. Is that big paddle bladed prop one MEAN looking prop, or what!!!!!

C172-XP parts

The Cessna "bulkhead stabiliser" that slides over the front dome of the McCauley prop is part number 0550340-1 and should be available from a Cessna parts outlet for about $10. The shims, part number 0752620-3, should aslo be available for about $4.

Pete

Good lookin' plane! Should be a Beauty when all painted up.

Roberta

McCauley Prop

Below is a photo of my McCauley prop before I swaped to Whirl Wind blades. The hub is the same as is the Cessna 210 rear bulkhead.

Rick McBride

McCauley Prop

Okay, one more I just found. This shows Van's spinner pretty well. You can see through the fiberglass where I mounted the front bulkhead. It sure sounds like the Cessna insert would work much better if it fits.

Rick McBride

Rick,

The Cessna front stabilizer that Penguin gave the part # for fits Van's spinner perfectly. On my installation it didn't even require any spacers at all, since the spinner fit up against it just as it mated up to the backplate (it is the only item that has ever worked on this entire installation without any modifications required!!).

By the way, the Cessna 210 backplate you used appears to mount up to the two steel plates that slide into the cutouts of the prop hub that the nuts fit into (which in turn the prop mounting studs screw into in order to create prop mounting bolts), which is exactly what I used. On my installation the custom backplate I have attaches on the backside (or engine side) of the plates, and is pulled rearward over the 1 5/8" prop spacer I had made until it touches the Lycoming ring gear in order to get a wrench on the prop bolts. On your installation it appears that the Cessna 210 backplate fits on the front side (or prop side) of the plates, and must pull forward up until it touches the prop blades in order to get a wrench on the prop bolts...is that correct? If so it must be very tight to get a wrench onto the prop bolts, but would eliminate the requirement of using a prop spacer like I have. Of course that would only work with the shorter cowling that Van's makes now & not the older long cowling like I have, but might be the way to go for those guys that have the newer kits that only come with the short cowling. From my experience with the long RV6 cowling installation it would appear that the Cessna 210 backplate might work with a short RV6 cowling without any prop spacer, and only about 1/4" removed off the front face of the cowling. This would eliminate the need for any bump having to be added to clear the alternator, but would of course require glass work to allow taking 1/4" off the front face.

The long RV6 cowling installation is alot better looking than the newer short RV6 cowling in my opinion, and it also moves the CG slightly more forward enabling a few more pounds of baggage to be carried (though it does reduce the G loading capability down to 4 1/2 to 5 G's or so...still good for any sport aerobatics). A McCauley prop installation on an RV8 may require more mods than just shortening the front face of the cowling 1/4" like an RV6 or RV7 ( I do recall that you mentioned you had to do a bunch of modifications to get your McCauley conversion to work on the RV8).

Travis,

You're correct, my backplate does mount to the two steel butterfly shaped tabs. The backplate however, mounts to the back of these tabs. There would be no way that I can think of to mount the other way around short of disassembling the prop bolts. My initial write up was incorrect when I stated the backplate sloped forward to allow easier bolt access. It does slope forward which further restricts bolt access. However, with the backplate mounted there is still room to insert a wrench. I've had the joy of puting on and taking off the prop at least a half dozen times. It makes it more of a pain to safety wire but that's as much a result of the .040 safety wire than anything else. As oppossed to removing a 1/4" from the front of the cowl, I simply installed the entire cowl that desired amount further aft. Not a good solution for a retrofit but easy enough on initial construction. The primary drawback is it does provide less room up front and will cause interference with the alternator. Another option would be to use the Whirl Wind prop and their backplate from the 200C prop. It uses the same McCauley hub and butterfly tabs. I didn't want to go this route because I didn't like the profile shape of their spinner. Choices!

Sure wish I'd know about the Cessna front plate earlier. Oh well, more fiberglass practice.

Rick McBride

McCaully prop

Be careful! The McCauley used on the Cardinal RG and the Mooney 201 can safely be used ONLY on engines with dampened/counter weighted crank shafts....