Renesis/RX8 Design Considerations

[jerms]

Hi all,

 

I'm currently doing a little bit of research into either a Cozy IV or an AeroCanard. At this stage, I'm probably leaning slightly toward the Cozy due to the number of partially built examples or examples built minus avionics and engine. My first question, probably more suited to the Cozy forum but hopefully able to be answered here is whether anyone considers buying a partially completed plane to be a bad thing? Caveat emptor, obviously, but beyond that and the lack of ability to say you built it all yourself, is there anything else I should be concerned about?

 

My second question, and a more relevant one to this forum, is regarding the use of the Renesis rotary from the RX8. I have read a few reports that utilising the Renesis instead of a 13B from an RX7 requires a prop of a larger size than the rear of the Cozy can reasonably accomodate. Is this the case, or do any other design concerns exist in the implementation of a Renesis engine on a Cozy. I understand that a few people are attempting this as it stands, and I guess I'd like to know how these efforts are going!

 

Finally (and thankyou in advance for your replies!), I have seen several turnkey manufacturers of both Rotary and WRX engines inclusive of gear reduction drive and other necessary modifications for aviation use. However, I have noticed that the cost of these engines seems terribly disproportionate to the cost of the stock standard auto engine itself plus redrive, PRSU etc. In the case of one of the WRX-based engines, an estimated overhaul cost is put at around $10,000 - this seems to fly in the face of much I have read that suggests that it should cost around 1/10th of that! I don't intend on buying one of these turnkey solutions, but I'm just wondering - am I missing something in this equation, or are these units as overpriced as they appear to me?

 

Far out... I can't believe I've managed to draw myself away from the soccer for this long! (in case people aren't aware, Australia is currently in a state of mass hysteria after making the second round of the World Cup for the first time ). I think I'd better get back to the soccer - it's like an addiction at the moment, but any responses or answers would be much appreciated!

[argoldman]

Hi all,

 

 

My second question, and a more relevant one to this forum, is regarding the use of the Renesis rotary from the RX8. I have read a few reports that utilising the Renesis instead of a 13B from an RX7 requires a prop of a larger size than the rear of the Cozy can reasonably accomodate. Is this the case, or do any other design concerns exist in the implementation of a Renesis engine on a Cozy. I understand that a few people are attempting this as it stands, and I guess I'd like to know how these efforts are going!

 

Finally (and thankyou in advance for your replies!), I have seen several turnkey manufacturers of both Rotary and WRX engines inclusive of gear reduction drive and other necessary modifications for aviation use. However, I have noticed that the cost of these engines seems terribly disproportionate to the cost of the stock standard auto engine itself plus redrive, PRSU etc. In the case of one of the WRX-based engines, an estimated overhaul cost is put at around $10,000 - this seems to fly in the face of much I have read that suggests that it should cost around 1/10th of that! I don't intend on buying one of these turnkey solutions, but I'm just wondering - am I missing something in this equation, or are these units as overpriced as they appear to me?

 

Far out... I can't believe I've managed to draw myself away from the soccer for this long! (in case people aren't aware, Australia is currently in a state of mass hysteria after making the second round of the World Cup for the first time ). I think I'd better get back to the soccer - it's like an addiction at the moment, but any responses or answers would be much appreciated!

 

Greetings Jerms,

 

I suggest that you contact Bruce Turrentine and Tracy Crook, the Rotary Gurus.

 

I am not aware that the Renesis requires a larger prop, just a different gear ratio to allow it to rev higher. From what I understand the porting of the Renesis allows that (because of breathing) with somewhat of a better fuel burn.

 

The cost that you stated above for the overhaul seems pretty close to the cost of a new renesis engine with ECU and PRSU. Bruce takes a new Renesis disassembles it, modifies it internally for aircraft use, provides an intake manifold, etc, etc. I believe, if available, he can rebuild a used renesis for a couple of thousand less. Tracy provides the gear box and electronics for spark and fuel injection. Both these guys seem to be a font of knowledge and are willing to allow you to pick their brains.

 

The overhaul on the renisis is peanuts comparably.

[gupri]

Hi Jerms,

after checking out all kinds of engines, the RX8 Renesis (Rotary genesis) seemed to be the "bee's knees". That was until I found out about the fuel consumption, which could reduce your aircraft's range by up to 50% in comparison with some other engines. There are workshops here in Australia, which will do Renesis conversions for aircraft at a reasonable price as well.

 

Have a Happy New Year and fun comparing other engines, their durability, fuel consumption and prices.

[argoldman]

Hi Jerms,

after checking out all kinds of engines, the RX8 Renesis (Rotary genesis) seemed to be the "bee's knees". That was until I found out about the fuel consumption, which could reduce your aircraft's range by up to 50% in comparison with some other engines. There are workshops here in Australia, which will do Renesis conversions for aircraft at a reasonable price as well.

 

Have a Happy New Year and fun comparing other engines, their durability, fuel consumption and prices.

.

 

Tracy is quoting the fuel burn utilizing his ec-2 to be comparable or even slightly better than aircraft engines. Apparently the rotary enables significant LOP running. All engines at T.O. power are fuel hogs

 

Tracy seems to be a straight up guy. Is there any indication that he is blowing smoke out of his rotors when it comes to the fuel burn???

[CBarber]

50% INCREASE IN FUEL COMSUMPTION????

 

I have not heard that number thrown around before. I am not trying to say the 13b/Reneses (or even the hoped for 16b) is or will be the ultimate engine....even though I have chosen to use the 13b (eventually to be turbo'ed, if all works out) in my Velocity. I do recall that 13b may have a slight fuel disadvantage depending on use. Something like, IIRC, .45 to .47 fuel usage between the Lyc 360 and 13b (sorry, I don't recall exactly what the unit of consumption is...I am on vacation in WY and have been out of the loop). I would not imagine that would translate to a 50% increase in fuel usage. Where did you come across that tidbit of info?

 

But, of course, I could be wrong.

 

All the best,

 

Chris