What type or make of crank shaft is in a DA-100? Is it Forged or multi-piece?

Thanks

multi-piece, press-fit together

Thats what I needed to know, thank you. Any body had issues with prop strikes knocking the crank out of time? (porting) Also what about loads on the engine causing the same issue?

Never had a DA for it to do it, but have had a Zenoah 62 to do it with a prop strike.

One way you can tell is to look in the exhaust port and turn the engine over until you see the piston get to the bottom of the port and then look and see if the other piston is in the same location, plus if it is out bad there will be a hard spot when trying to turn the engine over.

Interesting, other than weight is there a reason to use multi-piece cranks vs. solid forged crank? I know they use them in snowmobiles and chain saws but, they are not direct drive and use a clutch. The concern is under a load with a large prop the crank might have an issue (we just had this happen) The manufacture is suggesting using a smaller prop with the heavy load we are pulling. We are thinking they are suggesting this to get the prop to cavitate before the engine lets go.

Thanks

I think the main reason is cost, But I have never heard of one twisting under a prop load, Seems like it would have to be another problem of some kind, Both pistons get fire at the same time. ???

That is a good question, when the engine was sent back he said it looked as if it had had a prop strike but, that was not the case. He then mentioned it could have back fired and could have caused it. I still find that hard to believe and we would have heard the back fire. They fixed the crank and replaced the bearings, he also replaced the ignition timing sensor. I found that interesting, maybe that is the real reason it happened, they did not fire at the same time. Wouldn't this be an ignition box issue and not the timing sensor on the crank? The RPV we are flying is 42lbs and is designed to carry 20 pounds possibly 30. But the airframe is taking the stress, it is not being flown to perform aerobatics just haul weight and get to altitude quickly, 45-50 degree angles. So far the engine and aircraft have done this with ease at about 1/2 throttle. That is why we have found it hard to believe that we should run a smaller prop at the manufactures suggestion. It is being flown now with a Bolly 28-10 which seems to work great. The only thing we can figure is they are thinking that the prop bite is to much under that load and the crank is giving up before the prop, so by going to a smaller prop will cause the prop to loose bite and relieve stress on the crank. It would not make a huge difference in performance, it would just run our of juice at a lower altitude under load. Unfortunately, that is not what we want.

Any chance you're using an A H engine ? That would explain it...
Much smoke screening there in that explanation... Maybe a little CYA too....
Only current engines I can think of with forged one piece cranks are the not so current Twin Star and the Limbach 275...One piece cranks require rods with caps...Roller bearings for rods with caps are more $$$, rods have to be perfect, perfection is expensive, follow the money

twin3d

Your vehicles is very light for a 100 so you likely do not need a very high pitched prop. How it takes to the air would have more impact on the best prop in this case. Weight and wing design are lower in importance. You're almost in ultralight category with your flying weight using a 100.

Most prop strikes bend a crank and damage bearings instead of altering twin phasing. For a multipiece crank to get shocked out of phase would require one helluva prop strike. Send me a PM and we can talk offline after exchanging e-mail addys and later phone #'s. You don't want to discuss serious DA stuff anywhere there's a text trail.

Hey thanks for the reply. Sorry I did not get back to you sooner. Our clubs Big Bird was this weekend. We are waiting for that engine to return and see what was actually done. I am wondering if heat was a factor pulling that much weight climbing at such a steep angle.

I am running into other issues now. You replied to the information on my Brison 6.4. You were right on, what a wonderful engine. Crap load of power. I have it in a 37% Ultimate. I am having an issue with the spinner and prop slipping being it is an single bolt hub, any idea's?

I had a similar problem. I ended up drilling the hub for a pair of 10-32 screws to act as indexers, above and below the blade portions of the hub. No slippage problems ever since. PM when your able to.