Rocket Questions

[mooneyflyer]

Does anybody know: 1. What changes did Rocket Engineering make for -NB engine? And 2. What changes were made to increase gross weight? Thanks in advance.

 

[RJBrown]

TSIO520-NB is the stock engine in many Cessna twins. For ease of certification (an oxymoron if I’ve ever heard one) Rocket engineering used the whole power unit including turbo and propeller straight from the Cessna application. The 8 point motor mount and the exhaust/cabin heat system are Rocket specific.

this gave two interesting changes. A full feathering prop and a very large turbo. The prop allows a very high glide rate with engine off and is great to confuse linemen at the airport. On a pressurized twin the turbo must be large enough to both supply air to the engine and pressurize the cabin with one engine failed. This gives the Rocket a critical altitude (100% hp) of 24,000’

When the STC was first approved it contained a gross weight increase that just covered the conversion.

Later a second STC was approved for the 3200# gross. It was a remarking of the airspeed indicator and paperwork. Nothing about the airplane capabilities was changed. It just took them longer to get the full approval. The early conversions were sold with the lighter gross. Maximum landing weight is 2900# with all versions.
Rocket also did the flight testing to increase the certified ceiling to 31,000’ They did not complete this increase because it was not cost effective. As a part 91 the 24k (231) or 28k (252) is not a limiting factor.

[carusoam]

Great memory RJB!

Thanks for sharing all that detailed detail...

Best regards,

-a-