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Vari-Prop...anyone use them?
A friend of mine bought a 4 blade propeller from Vari-Prop. Until today, I had never heard of them. Does anyone know about this propeller company? Are their props on anyone's airplane? Safety record, or lack thereof?
Inquiring minds want to know! I did a search but the info was almost 6 years old. |
From Mr. Google
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Interesting idea, especially for people with solid cranks. Looks like wood blades, so they'd need metal leading edges if you think rain might be along your flightpath. There is a picture of one mounted on a -6A or -7A on the webpage, and the page is dated 2007, so surely there are some in-flight reports by now...
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I have one of their props (3 blade), but ain't flying yet. The props themselves are made by Props Inc (I think). They do have a solid epoxy edge.
The controller is nice and simple, but does require some extra plumbing for the hydraulic line (not as nice and simple as using the oil pressure from the engine). Where to mount the master cylinder can cause a nuisance too (mine is between the panel and the firewall). |
Corey, how is the hydraulic pressure conveyed to the hub? Some kind of sliding collar?
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Any idea of the cost? I could not find any pricing info on their website.
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Apart from the advertising, their site isn't very good at all. But an interesting idea. I'd think about it when the time came.
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YouTube
Search "Variprop" on YouTube and you'll find a nice little video by one of the canard folks.
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![]() You can see the center piston (for lack of a better word), which manages the pitch of the blades. There is a pin at the end of each blade that slots into the piston. The hydraulic pressure comes in through the sliding collar at the base of the hub, you can see the hole from the threaded fitting. (You have to secure the fitting so it doesn't rotate, which may or may not be easy depending what you can use as a mounting point for a custom bracket). Here's a picture of one of my blades: ![]() |
I believe Mark Sletten and Kelly Landrum are both flying these props on Subaru powered aircraft.
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[quote=ccrawford]I have one of their props (3 blade), but ain't flying yet. The props themselves are made by Props Inc (I think). They do have a solid epoxy edge.
Yes, that sure looks like a Props Inc blade. Mine also had the solid epoxy edge. The blade root looks similar to the one I had also. Please be careful. Review the thread below to understand my concern. http://www.vansairforce.com/communit...ad.php?t=62775 I now have 100 hours on my RV-4 with a Catto, 2-blade. I am very satisfied with the Catto. |
[quote=timothywhigginbotham;692555]
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The particular prop in question is a 4 blade 88" hydraulic constant speed prop. Wonder if that makes any difference?
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Props are highly stressed components and like most things in experimental aviation, it is rarely a good idea to be one of the first to buy any new device on the market until the fleet has garnered a bunch of trouble free flight time. We have seen this so many times before on all sorts of components.
A prop failure can kill you and/or wreck your engine or plane. I can think of at least 6 new brands which have had catastrophic failures in the last decade. Stick to proven stuff, let someone else do the beta testing on new prop designs. |
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Owner of the RV-4
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If Jeff Bertuleit @ Props INC (or anyone else) made that statement, it's not true. He is probably referring to the RV-8 in OK that also lost a blade in-flight. The RV-8 was totaled and the owner was injured. Jeff got us mixed up repeatedly. He even sent my prop to the guy in OK by mistake. Jeff did feel one of the other props was abused because the owner planned to operate up to 3000 RPM. My prop never exceeded 2640 RPM before the event. My engine sure did when the prop came off though. Lots of damage to the valve train and other stuff. I understand there was also a third prop that failed. At one point Jeff was being sued over this. I chose to not participate in a lawsuit. My insurance carrier indicated they may pursue damages. I am not referring to the hub design. I have no experience with it. The wooden prop blade in the picture looks identical to the one I lost... I had no knowledge of the other two Props INC failures before my 1st flight. I have nothing to gain or lose at this point. We don?t put the big experimental sticker on for nothing. You get to decide for yourself. |
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Just for further info, I had seen that thread before which is very interesting. Vari-Prop uses their own blade retention mechanism (not the weird compression, whatever-it-is system the ground adjustable hub from Props Inc uses). There are 3-4 lag bolts going directly into the blade body which are epoxied in. The lag bolts fix a metal retaining ring around the base of the blade, which I believe is also epoxied.
I don't have a good picture of that, but I can get one if anyone is interested. There are some folks successfully flying with these (and apparently lots of airboats), but certainly not as many as the mainstream brands. |
Testing, testing...
I have seen two in current operation installed on local airboats, both with composite blades per the website. Both had no apparent issues...
Smokey http://www.variprop.com/ FYI, The hub/blade system VariProp uses and the ill fated Props Inc system previously mentioned are two completely different animals. |
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MT
MT uses a wood core in their composite blades as well. I saw a cut-away of a MT blade once, and it was quite interesting.
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Prop me up...
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Having been down the prop trail nine times and seen the current available options out there my choices for Ground adjustable based on inputs from friends flying them FYI: 1. Whirlwind GA (all composite blades) 2. Sensenich GA (all composite blades) My favorites I flew many hours, owned and tested. 1. Catto 2 Blade wood/composite with nickel leading edges. www.cattoprops.com 2. MT Fixed Pitch wood/composite http://www.mt-propellerusa.com/en/mtusa/products.htm 3. Gary Hertzler wood/composite hertzler@yahoo.com V/R Smokey |
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What are any of you doing with Vari-Prop? Is anyone actually flying one successfully? Capt Jim |
The variprop.com URL is for sale on GoDaddy. I don't expect to see much customer support.
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I gave up on mine. I couldn't get comfortable with how the individual blades sit in the hub and the mechanical link to rotate the blades. If you are a better ME than me (likely!) then you might be able to modify it slightly to be reliable.
I still have it if you want to check it out, I'll sell it to you cheap cheap. |
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