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Bryan Winberry wrote:
I’m a novice when it comes to props. So, could I get some advice about the following prop that a guy has for sale.
I have a Renesis with the RD-1C (RV 7). Plan on using the rotary cowl.
The prop is question is a 3-blade MT. Model MTV 7-C-187-139. that’s 73” diameter, electrically adjustable.
Firstly, the bolts are 7/16 and the PSRU is 3/8^th . Would there be a problem opening the holes?
Secondly, the website (MT) indicates that 160 is max HP for the prop, but it also says that 175 is max diameter. This one is 187cm (73”).
I have sent an email to MT regarding this, but want to let it get kicked around here on the forum.
Lastly, in the construction manual, Van’s doesn’t recommend aerobatics with an electrically adjustable prop.
Thanks in advance for your replies.
Bryan
Like someone else said, the max hp sounds wrong, especially if it also says a smaller max diameter. Looking at the model #, it seems likely that the '187' in the model number is actually the prop diameter. Also, a 73" diameter 3 blade prop limited to 160 hp would have blades as narrow as toothpicks. Is that the case? Must be specs for a different model prop.
Van probably says no acro with electrics because they have much slower response time than hydraulic props. Still not as bad as *no* response time from a fixed pitch, & they do acro all the time. :-) The issue is over-speed if they are in flat pitch going up & can't respond quickly enough to limit rpm going down. The throttle can solve this, just like it would with a fixed pitch prop; just extra work load for the pilot. A more significant question is whether MT approves it for acro.
Charlie
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