Updates? Wish granted, but settle in for the long haul.

Maybe I should have a “Paint my Merlin” contest. I’m leaning toward a nice royal purple at the moment, subject to change.

Tom.

Think these lot have any scrap parts?

http://www.51-factory.com/inventory.htm

Yes, when ever I visit that site, my job drops and I start to drool. I have called them, and one of their guys is asking the boss if they have a hopeless crankcase for sale.

As for the epoxy paste, I may consider that, but I like the idea of repairing things properly. The supercharger and wheelcase I have are otherwise functional, and if the cost is not brutal, I’d consider proper welding.

Cheers, Tom.

Guys;

Thanks a lot for the info and the pic. You gotta hand it to the Germans, they could design!

I hate to overstay my welcome, but if you happen to have a thousand more pics, feel free to beam them over. I love looking at other people’s airframes.

Cheers, Tom.

Hi Guys;

Thanks for all the replies. Of course, Google was my first approach, but I have found things don’t always show up on Google. So that’s why I was hoping someone might have bookmarked a site or two. One that I did find, is the rebuild of Red 7, but the pictures are so small, they’re cute but not useful.

Chumpy, thanks for the pic. I was surprised to see how in the middle the spar appears to be. Yes, by the way, the Spitfire is out. A Titan T-51 looks about right for a Spring Chicken like me, but the price tag’s high. And I’m still waiting to see how the FWF package survives, after one in-flight crankshaft breakage. Aside from a few cosmetic compromises, I like the T-51, and have been studying it for fun.

Then, as I was innocently surfing, I just happened upon some BF-109 Youtube clips, and God, she looks like a mean, purpose-built beast. So that’s why I want to get a bit cosier with how the airframe looks. I also love that whistle from the variable charger.

Shorty01, thanks for the prints link. I can’t recall the last time I felt rich. I guess that begs the question; “what the hell makes you think you can afford anything more than a balsa model?” Answer, call me a dreamer. At least that part’s realistic !

BrewerJerry, now that looks like an outstanding place to start snooping. I will register right away and get reading.

Thanks again all.

Cheers, Tom, (wanna-be tail dragger).

Hi MkI and Beurling;

MkI; Thanks for getting back to me about your PSRU and propeller. I was curious what level of confidence you have in these two units, overall. I guess what I revert back to is fear of the unknown, and vibration plus its effect on any mechanical unit are unknowns for me.

I also simply do not know who to trust when it comes to buying a PSRU. Company claims are simply too much like sales pitches, and often backed up with too little data to believe. Do Hy-vo chains really attenuate or dampen vibration? Not according to some manufacturers. But absolutely according to others that use these chains.

So I have been searching to find incidents of PSRU failures. I am trying to narrow my focus to spur geared units, not chains, helical gears and cogged belts, although I have found failure examples for all of those. I want to have some understanding of failure modes, and see if there is any common parts that seems to fail. So far, I have found that output shafts seem to snap and this has surprised me a bit, since I would have assumed that this would be a pretty beefy part. This would seem to suggest that it’s breaking due to tortional fatigue (don’t quote me on that) which in turn might indicate propeller vibration and power pulse issues from the engine. Perhaps these two vibrations are ganging together and making the forces bigger than predicted. You know, the propeller does its worst just as the engine does the same. I can kind of picture it, but this is pure speculation on my part. All I know is that PSRU’s are failing. Are they failing more often than props, engines???

Beurling; I’m surprised if there are belted units that handle 1000 HP. Thanks for letting me know. If you have any links on PSRU’s please share them, especially 400 HP + vendors.

I have tried to find the Camdrive vendor. Are they no longer operating?

Thanks guys, Tom.

MK 1. I like your soapbox. Your soapbox is helpful.

Hi;

OK, good points and bad points. The 100K estimate for this project is a bit of a spleen crusher. I hate reality, but at least my dear sweet wife won’t likely read through this forum. You are no doubt closer to the grand estimate than I would be, me trying to put a positive spin on cost control. 100K, huh? In the immortal words of E.T., Ouch.

But then there is some good news. Your homemade PSRU intrigues me, but as you’ve alluded to, this is a pretty significant piece of hardware. And using a Chevy LS2 means more power, more reason to get it right, more likely self destruction if I get it wrong. My biggest concern in making a PSRU is the vibration issue. I believe I can manage most other challenges, from casting or machining from billet, choosing flight-worthy spur gears, bearing choices, oil circulation, and possibly even accessory services drives that exit the PSRU at various locations. But the vibrations in their many forms, well, that’s like black magic to me.

I guess what you’re relying on, in your particular case, is the appearance of smooth operation in the first 62 hours of service. Question; are all damaging vibrations detectable through the seat of your pants, or are there types of vibrations that are damaging yet un-feelable? I went through the EPI website, and have gotten some pretty awesome replies from Jack Kane, who based on his replies, I’d have to label “Mr. PSRU.” I believe there are enough separate forms of vibration to scare away the average higher-math-challenged rookie like myself. But again, if the vibration issues were solvable, I would be willing to at least do some preliminary designs and hardware sourcing. Metal working on a mill has its challenges, but that’s the stuff I enjoy.

Now there’s the prop. Again, a homebuilt affair for you. Please, tell me more. Three blade, 6 plies of birch, kevlar coated. Do you mean a layer of kevlar is epoxied to the surface of each blade? And the bosses, I see these as cylinders that the prop ends get stuffed into and epoxied. I think the props made in BC by GSC Systems have a bolt through the wood to act as a fail-safe to keep the blade in the hub if the glue fails. Do you have that arrangement? Just curious. I assume the sandwich block hub is much like GSC’s but again, correct me if needed. I’m not sure if you ground adjust all the blades at the same time (they all move as one unit) or if you adjust each blade spearately. If so, you have to use some sort of angle gauge, no?

Do you happen to have any pics of the prop close up, or the PSRU?

Like any over-zealous homebuilder, I have given thought to making the prop. I cannot believe it’s impossible, even at the higher power levels. That just sort of ups the ante. With cnc machinery, at least the likelihood of getting 4 or 5 blades all the same shape is pretty good.

Thanks again and hop onto your soapbox any time.

Tom.