WOT Descents..Who's doing them?

[Seth]

Even at 500FPM?  I can easily exceed redline as well...if I try, but at 500FPM I think I only see about a 10 to 15% increase in IAS.Does the Rocket cruise that close to the redline?  Even at altitude?

 

Yes - If I don't power back at 500 FPM I'm in the yellow arc indicating 180 knots (at altitude). 

 

Actually, way up high, when decening from the mid teens I'll decend 500 FPM WOT until the indicated speed starts to creep up, then I'll pull back the power. 

 

If it is very smooth air i'll decend in the yellow arch but if there is any indication of even light turbulence during the decent I'll pull back into the green arc which is still 170 knots indicated, and up high, that's still 180-200 true.

 

-Seth

[tomn]

My 66E cruises in the yellow arc all the time - even up to about 10k I think. For descents, I have to pull back on the MP, will overspeed things quickly if I don't. It is sometimes difficult to get it slowed down enough for descent in rough air. Since the gear down speed is low (120mph) and the flap speed lower, it takes some careful work and planning to make it work out without pushing it to far. As for a WOT decent - I think I'd really have to drop the RPM a long way to have any attempt at it.

[jetdriven]

Not in a Mooney Does 150 knots until 3 miles out count for something? You getting your bird painted out here for Christmas?

Getting close, Gary, with the 150 knots.  Now push it a bit more.

 

Wont have it painted by the end of the year most likely. Too many mods and prep repairs, not enough time to do them.

[Shadrach]

I was just pointing out to Ross something that he knows already. That these are far from paper distinctions that could affect the V speeds being discussed. To answer your question, though, yes later models did get a rear spar doubler that beefs up the flap mounting quite a bit. Many older Mooneys have cracks in this area. You can add the doubler if you wish. There is a Service Bulletin that provides details.

Jim

There were some actual changes and some paper changes. What I know above all else is that while Mooney has made great planes, the company has been less than stellar in the paperwork dept. Every time an IA with anything less than absolute Mooney specialization has looked at the plane they tell me my IPC is not the latest revision for the airplane. Why? Because Mooney's website showed my IPC (Man203) as only being for C,D and Es... The website was revised (read corrected) 7/12/13 because I called the company and begged them to change it as this year was the 3rd time an IA claimed my IPC was out of compliance and that plane was not technically airworthy.

As for Vspeeds.

Look in the TCDS.

An E Model in the same serial# range as my F (below 680001) has a Vne of 189MPH while my F has a Vne of 200MPH. These birds were built side by side in the same year. Same goes for Vfe in that S/N range... E model has a Vfe 100mph while my F has a VFE of 105MPH... Why would that be? They were made on the same line at the same time with the same wing and flaps... Funnier still is that the white arc in my F starts at 100mph (per what the TCDS says for the E), not 105MPH as the TCDS states for my model. Sometime after 1968, the E, F and C all got the same Vspeeds.

If you look at the J, it's Vspeed numbers differ from S/N to S/N and it even has a partial flap Vfe.

I am sure there were "some" structural changes over the years, but if you believe every one of these TCDS differences between models of virtually the same airframe represent material changes to the airframe then I think you grossly underestimate the lack of consistency and/or organization regarding both the factory and the FAA during the 60s and 70s.

[Jsavage3]

I run WOT until I'm hitting the "47" (power is 65%) number, then I'll reduce MP to maintain the 47.  Ram air open until 5K in summer or 3K in colder months.  At 300 fpm down, I'll gain 10 to 15 knots ground speed and I start that so as to hit pattern altitude 5 nm out (or IAF altitude at the fix).  I usually see top of the green arc or slightly into the yellow all the way down.

 

To counter turbulence, I recently started experimenting with reducing RPM at TOD to say 2200 to 2300 RPM and then adjusting MP from there to keep the 47...supposedly, per the Mooney manual, it keeps things loaded and causes less internal flutter...and I've noticed it also reduces IAS.

[jetdriven]

Why are you even reducing RPM?  Our J's cruise nowhere near the yellow arc, and there is enough room in the green arc to nose-over with cruise power settings (esp LOP) and go downhill at 1000 FPM or more

Amen brother. The top of the green is 200 MPH and I never get close to that with a WOT descent. Usually its 180 MPH

[Bob - S50]

Remember, I'm pretty new to the J, but here it what I do and why I like it.

 

Cruise at 6500 - 9500 WOT 2400 RPM, LOP.  When it is time to descend...

 

RPM back to 2200 RPM, 500 fpm.  If the MP is over 20", pull it back to 20" and keep pulling it back during the descent to keep it at 20".  Periodically enrichen to see if it increases EGT.  If it does, enrichen to peak, otherwise let go of the mixture.  I do it all this way for a few reasons.  I've read we do ...not... want high RPM and low MP in the descent because it can cause ring flutter that may eventually break a ring or landing.  I think I got this from one of Mike Busch's webinars and from a Lycoming Flyer article.  In spite of the high green arc, I don't want to push the limit because of our hilly terrain I do not want to suddenly run into turbulence near the top of the green and more importantly I want my wife to feel comfortable.  Doing it this way also sets me up for flying 'by the numbers' from a MAPA Safety Foundation document I found.

 

At pattern altitude I can leave the RPM at 2200 and 20" and get a comfortable speed for approaching the field.  Then depending on whether I'm flying VFR or IFR, MAPA says these power settings will work:

 

2200/18"/clean = 105K

2200/18"/gear/GS = 105K

2200/13"/gear/GS = 90K

2200/13"/clean = 90K

2200/18"/gear = 90K

2200/13"/gear/GS = 90K

2200/13"/gear/GS/full flaps = 80K

 

On may airplane it is actually 17".  Set the RPM at top of descent and all I have to do is mess with the throttle and configuration until short final.

 

When I want to slow below 90K I pull the power back to maybe even below 13" and while I'm there I push the mixture full rich (I'm near sea level) and prop full forward.  At the low power setting it makes almost no difference and I'm all set up for a potential go around.

 

Bob

[aaronk25]

20 min ago I descended from 5500 ft agl and was cruising at 2500rpm wide open 20 lop pointed nose down at 800fpm indicated top of yellow never touch mixture.......I'm lazy, except I leaned it more once clear of active

[kmyfm20s]

This actually answered one of my original questions. Tortional vibrationat at low RPM and high MP!

 

http://mooneyspace.com/topic/8833-m20j-prop-vibration/?hl=%2Bprop+%2Bbalancing#entry96170

[AlanA]

One more vote for WOT descent. I like this method for several methods. It keeps my engine temps more constant, I get home faster, and the Mooney slows down fairly fast if you want it to once you pull the throttle back, especially once you get slow enough to put the gear down.