Landing Gear Speeds in Older Electric Gear Mooneys

[Marauder]

Well, searching this forum can be fun... 

 

I have been reading the thread on speed brakes and it got me to thinking to why they are needed. For me with the low VLo & VLe speeds (104 KIAS) for the electric gear, it has always required me to plan ahead for my descents. When I'm VFR, it's easy... 100 miles out, started descending  When flying IFR, things are a bit more challenging. Over the years I have learned to ask for lower early and often. I think the controllers must think I'm a parrot (sorry Mike) when I repeatedly say, "Ah... Polly wants lower".

 

So... can someone tell me a couple of things. What is the limiting factor on the electric gear speed for older Mooneys? I have heard it is because the gear doors can't handle the higher speed and I also have heard that our older gear motor is not up to the task. Is it either of these and if not, what is causing the limitation?

 

The more important question is whether or not there are any STCs out to increase the gear speeds to something higher than what they are now? 

[jetdriven]

I haven't heard of STCs to increase gear speed but 1977 brought the 40:1 gear ratio which doubles the time for the gear to cycle but halves the load on the actuator. There was a service bulletin that came out in 1977 for those and later models which raised the gear speed to 153 MPH IAS. Ours has this done at the factory but they didn't change the 125 MPH placard.

[Marauder]

Thanks Byron. I'm going to dig into this a bit. A friend has a 77 on the same field as my mechanic and Weber's is not far from me as well. Getting the speed up to 132 KIAS would be a big improvement over 104 KIAS. Do the 77s have inner gear doors as well?

[Marauder]

I haven't heard of STCs to increase gear speed but 1977 brought the 40:1 gear ratio which doubles the time for the gear to cycle but halves the load on the actuator. There was a service bulletin that came out in 1977 for those and later models which raised the gear speed to 153 MPH IAS. Ours has this done at the factory but they didn't change the 125 MPH placard.

 

Looks like the gear increase speed for the 77s was just a placard change. http://www.mooney.com/images/pdfs/sb-pdf/sbm20-209.pdf Probably based on the changes you described. Do you have the Eaton motor? I'm wondering why no one tackled this for the older Mooneys. 

[rbridges]

I had a brain fart the other night.  I dropped my gear at ~130 knots.  My ASI was kinda dark and I looked at the wrong color arc.  Anyway, I could feel the johnson bar pull a lot harder when I released it.  That alerted  me to something not being right.  I checked the flaps and gear when I landed, and knock on wood, everything looks good.  

 

The force on the johnson bar was noticeably heavier, and I imagine repeated high speed drops probably wouldn't be healthy for the plane.

[Marauder]

I had a brain fart the other night. I dropped my gear at ~130 knots. My ASI was kinda dark and I looked at the wrong color arc. Anyway, I could feel the johnson bar pull a lot harder when I released it. That alerted me to something not being right. I checked the flaps and gear when I landed, and knock on wood, everything looks good.

The force on the johnson bar was noticeably heavier, and I imagine repeated high speed drops probably wouldn't be healthy for the plane.

You bring up another good point. Why aren't manual gears capable of doing higher gear speeds? Is it based on the amount of force required to move the bar that was found unacceptable at higher speeds or was there a structural element that was getting stressed. I'm willing to bet that the force speeds were the limiting factor, not the hardware.

Would I spend $3k to modify my landing gear to drop at 132KIAS over paying $8k for electric speed brakes? Absolutely. I'm going to keep digging on this topic.

[carusoam]

With the C, the gear pulls down very hard/quick at high speeds... very soft and gentle at lower speeds.

Always make sure the gear is locked in the up position. It is a surprise when the J bar flies through the cabin and thunks into the down position. It has enough force to really hurt....something.

Whether the doors or the gear themselves are responsible, no can tell...

It would make sense that the 40:1 gear ratio is better to handle the transition at higher speeds.

Expect the forces to grow at a rate with AS^2

Gear make a pretty good speed brake if you can deploy them earlier.

Speed brakes can be deployed at very high speeds. Redline on some planes. This would allow to fly full speed ahead while descending. (check your POH before using this advice, as usual).

Thus the desire to change the name to potential energy dissipators...nobody really wants to slow down to change altitude. Good idea if your customers are only engineers or physicists...

Flap and gear speeds of my C were set pretty low....

Best regards,

-a-

[Andy95W]

Wonder if you could slow down, drop the gear, and then speed back up in the descent (to 153 MPH or 132 kts.). Other airplanes have this as a difference between gear operating and gear extended speeds (Vlo vs. Vle).

[rbridges]

the reason I was worried about the doors is because a local guy in an Ovation 3 had to get new front gear doors after lowering the wheels when well past gear speed.  Bent the hinges really bad.  They tried to rebend them but they never closed properly afterwards.  Had to order new ones from the factory--$$$$.  No one knows how fast he was going when he did it, but everyone figures he was moving pretty damn fast.