Rolls Royce NENE 10 issues

[CF104]

Standard engine issues.

Rolls Royce Nene 10

I’ve been doing some flying to test out the Nene 10 as currently modelled. I’ve come across a few issues that differ from the real world Nene 10. Granted it’s been about 30 years since I’ve worked on the CT-133 but these are the things that stand out to me.

 

I’ll begin with the start. OAT @ 15°C, winds calm

EGT lags severely during the start. Engine is at idle before EGT is even off the minimum needle indication of 200°C. Digital indicator showing 171°C and climbing. After RPM stable @ 24%, EGT keeps climbing to 586°C after several seconds.

The Nene 10 EGT system is quick reacting and has no real perceptible lag in indication. The start acceleration is too fast. On batteries the start takes about 30-35 seconds from starter engagement to 28%. Idle EGT should be in the 430°C to 480°C range and <540°C. Idle Fuel Flow is too high. It is indicating 1600 PPH. This should be 750-800 PPH. Idle RPM in sim is 24% (J33?) whereas the Nene 10 is 28% +/- 1% (this is for CT-133 after mid 60's. Before this the Idle was 20%).

 

Takeoff Power

Takeoff Fuel Flow in sim is showing 4000 PPH. This should be 4800-5000 PPH. Takeoff EGT in sim is 511°C whereas the Nene 10 will be @ 650-680°C and <695°C (takeoff max).

 

EGT indicators

 

The modern instrument panel (post AUP) EGT gauge has incorrect markings. The green arc is off scale low and goes to 570°C and the red lines are @ 760°C and 790°C. The green arc should be 200-595°C with 2 individual red lines at 695°C (takeoff) and 800°C (hot start).

 

The classic analogue gauge markings are also incorrect for the Nene 10. In sim the green arc is 250-700°C and the red lines are 700°C and 900°C. The green arc should be 200-595° and the red lines at 695°C (takeoff) and 900°C (hot start). The early CT-133 manuals had the Nene 10 hot start limit @ 900°C but this was reduced in the 70's to 800°C to improve engine reliability.

 

 

Idle thrust

 

Idle thrust is too high. In sim it will break away and taxi @ 28 knots at idle. The CT-133 will not break away at idle thrust. Standard procedure is to hold the brakes while powering up to 60% rpm, then release them and modulate the power down to maintain taxi speed. Usually somewhere in the 30-35% rpm range depending on fuel weight. The early CT-133 EO's even state that it will need 55% RPM to start rolling. On a level ramp the jet will slowly come to a stop at idle thrust.

 

I’ve included links to some good CT-133 ground run footage which substantiates my observations.

 

Video of CT-133 NENE 10 at idle, RPM 27.7, EGT 431, FF 750 PPH

Video of CT-133 NENE 10 at idle, RPM 27.7, EGT 476, FF 750 PPH

Video of CT-133 NENE 10 accelerating to TO power

Video of CT-133 NENE 10 accelerating from idle to 74%

Video of CT-133 breakaway thrust for taxi

Video 2 CT-133 breakaway thrust for taxi

Video of CT-133 battery start - 30-35 seconds to idle.

 

Cheers,

John

 

[jocko417]

Good stuff!

[Alien0071]

I love the interest this aircraft has stirred up and the truly knowledgeable people commenting on this T-33. It really shows how many people are so dedicated to aviation and have a perfectionist attitude. Don't ever give up insisting on the best possible quality whether on aircraft or in everyday life. It is always the best recipe for success.

Really interesting and informative with all your provided links.

Thanks