Tecnam and Sensenich

[Roger Lee]

I just secured an LOA from Tecnam to install the same Sensenich 68" 3 blade prop that some of us use on the CT. Since they only had a 68" fixed pitch prop set for 5300- rpm this should be a good upgrade for them. I was kind of shocked they were up for it.

This would be the same prop that some of you would use if you switched from the Neuform. It's a good prop.

[Tom Baker]

I have a P2008 in the shop that was switched a Sensenich prop sometime back. The one bad thing is the spinner doesn't match up to the cowling. 

[Roger Lee]

Hi Tom,

I was surprised that Tecnam put a fixed pitch prop on these aircraft with too coarse a pitch.

Were they able to get an LOA to? I thought this may have been too easy.

Going to get a spinner for this Tecnam from Sensenich (I hope).

[Tom Baker]

Yes, this airplane has a LOA for the Sensenich. It was to remove a GT Propeller GT-2/173/VRR-FW101, and install a Sensenich 3 blade propeller 3BOR5/R68C.

[Roger Lee]

That's the one. I have to buy this and install it and I'm looking forward to see what another 350 rpm will do for him.

[FlyingMonkey]

Question:  If you replace the 66" Neuform with the 68" Sensenich on a CT, what is that going to do to your rpm?  Typically a larger prop disk means lower rpm, but with a ground adjustable prop you can make the pitch slightly flatter to compensate for that.  So is the advice the same, go for 5600-5700rpm WOT at normal cruise altitude?

[Ed Cesnalis]

8 minutes ago, FlyingMonkey said:

5600-5700rpm WOT at normal cruise altitude?

the advise you gave above does leave power unavailable for cruising at their normal cruise altitude    If you want all available cruise/continuous power to be normally available, than that is too flat.  

It is however a really good setting especially if you live and fly at modest altitudes.  some reasons this extra flat works well down lower:

• below 7,500' DA max continuous power setting achieves above 75% power and isn't advisable.
• best speed is less desirable down low anyway due to noise
• this flat setting provides additional climb power for the 1st 5 minutes before the cruise limitation begins.

its easy to see the 'conflict' in the advised setting because its for your 'normal cruise altitude' but it can't be used for cruising at your normal cruise altitude.

Normal cruise in a plane limited to 100hp for me means cruising with all available speed and that does have a minimum altitude of 7,500' for cruising altitude and does have a slightly coarser pitch requirement if your prop is adjustable.

the advise you gave above does leave power and therefore speed unavailable for cruising at their normal cruise altitude.

[FlyingMonkey]

Ed, I understand your criteria are a little different, with your typical cruise altitudes well over 10,000ft.  I know you cruise at WOT and need all the performance you can get, so right at 5500 WOT is probably better for you.

Down here in the lowlands, Roger's 5600-5700rpm rule works very well.  I like to err a bit on the flatter side, since nobody ever got killed by having too much climb.    I often cruise below 3000ft MSL, and can get about 5700rpm in level cruise WOT at that level.  As for cruise performance, here's a shot from this past weekend, at 5500ft and 5200rpm.  As you can see, I am getting 113kt KIAS, 123kt TAS, and 121kt GPS ground speed.  At 5500rpm I was getting 130 KTAS or better.  The CT loves the cool winter air!

  

[Ed Cesnalis]

1 minute ago, FlyingMonkey said:

Ed, I understand your criteria are a little different, with your typical cruise altitudes well over 10,000ft.  I know you cruise at WOT and need all the performance you can get, so right at 5500 WOT is probably better for you.

Down here in the lowlands, Roger's 5600-5700rpm rule works very well.  I like to err a bit on the flatter side, since nobody ever got killed by having too much climb.    I often cruise below 3000ft MSL, and can get about 5700rpm in level cruise WOT at that level.  As for cruise performance, here's a shot from this past weekend, at 5500ft and 5200rpm.  As you can see, I am getting 113kt KIAS, 123kt TAS, and 121kt GPS ground speed.  At 5500rpm I was getting 130 KTAS or better.  The CT loves the cool winter air!

  

That does look like a nice setting for you.  What do you get at 7,500'?  What altitude can you cruise WOT at that pitch?

[Ed Cesnalis]

What's your best climb rate at this setting?  Best meaning solo and light.

[FlyingMonkey]

21 minutes ago, Ed Cesnalis said:

What's your best climb rate at this setting?  Best meaning solo and light.

It's all temperature dependent.  In cool air like we have now I see 1000-1250fpm climb solo, in the dead of summer it's more like 850-900fpm.  I don't know what my cruise is at 7500ft, I'll test that when I get a chance.  I have the small, non-tundra wheels, and mine seems to be one of the faster CTs. 

BTW, those climb rates are from my home field at 940ft MSL.