Question about constellation brakes

[Matthew Black]

Why can't the brakes be applied while the gear is being retracted? Is this because there is not enough hydraulic pressure for both at the same time? Here's a photo from the landing gear lever.

 

[Magman]

I think this is not the right “ Corner” but I’ll take a WAG.

Applying brakes will create heat and also the possibility of a pressure leak of a

flammable fluid. Putting this assembly inside the wheel well may not be good.

Also many aircraft have a “ strap brake” that stops wheel rotation.

Comments?

 

[Matthew Black]

I think this is not the right “ Corner” but I’ll take a WAG.

Applying brakes will create heat and also the possibility of a pressure leak of a

flammable fluid. Putting this assembly inside the wheel well may not be good.

Also many aircraft have a “ strap brake” that stops wheel rotation.

Comments?

This does sound very likely, thanks!

 

[NoHeat]

Don't know. But the nose gear is especially long:

 

[Bell206]

Is this because there is not enough hydraulic pressure for both at the same time?

This is my guess as there have been other aircraft that had the same limitation. Some of the older low PSI hydraulic systems didn't have the power to handle the demand when the gear lever was selected. Once higher PSI systems were introduced things changed on various aircraft where the brake systems automatically stopped the main wheels from spinning during the retract phase.

 

[Magman]

My recall is watching Connies take off and one main gear would retract ever so

slowly. They all seemed to do it.

Other aircraft used a de- booster to lower brake pressure and the Brake System

probably had an Accumulator good for several brake applications.Plus compressed

air for emergency use that would lock up all.

Aircraft with long landing gears and smaller wheel wells often use a “Shrink Rod”

of mechanical linkage to allow it to fit the well.


fyi- Connie/ C-121 pilots used to brag that they could handle 3 pieces of tail!

 

[Matthew Black]

I guess while we are talking about Conie, why would the PRT engines cause flames from the exhaust?

 

[Bell206]

why would the PRT engines cause flames from the exhaust?

Part of the recovery turbine operation involves mixing fresh air back into the exhaust stream which in turn ignites with the remaining unburned fuel. If you dig deep enough in the old manuals you'll find "flame" charts which were used to tweak the engine mixture cruise settings or troubleshoot issues based on the color of those flames.

 

[Matthew Black]

Part of the recovery turbine operation involves mixing fresh air back into the exhaust stream which in turn ignites the remaining unburned fuel. If you dig deep enough in the old manuals you'll find "flame" charts which were used to tweak the engine mixture cruise settings or troubleshoot issues based on the color of those flames.

That's a very interesting way to monitor fuel flow!

 

[Bell206]

That's a very interesting way to monitor fuel flow!

Its more like a visual verification your fuel flows are good. The flight engineer had fuel flows on his panel. But if I recall correctly, the PRT engines required a different power management process given the turbines added more engine power downstream of the combustion process outside of the fuel flow indications.

 

[Magman]

The PRT’s were a rather interesting piece of equipment. IIRC each could

re-introduce about 120 hp to the engine. And there may be 3 on the engine.

I never got involved with Connie’s but I did ride in some.

Forward Facing - Civilian

Aft Facing. - MIL

Your interested in Connie’s because __?

 

[jbDC9]

My guess on the “no brakes during retraction” thing is to reduce torque/rotational loads on the gear legs while in transit. While flying the B-17 we were cautioned to brake first, then retract. Apparently the wheels spinning and braking would put extra stress on the trunnions and other linkages.

 

[Magman]

So, I wonder if the intent of the placard is to do braking before initiating

the retraction cycle OR do no braking at all?

AFM,POH OR -1 anyone?

Flying “Crew Type” aircraft is not necessarily easier than a single seater.

There has to be a lot of coordination amongst the crew while persuading the

beast to take to the sky. And they must all speak the same “ language”!

 

[Fearless Tower]

Can’t say for certain on the Connie, but on the B-25, the concern is the brakes are so strong/effective that you can actually shear off the valve stems by stopping the wheels too quickly while the momentum of the massive tires keeps going.

 

[Magman]

To do that it seems 2 things are needed:

1. Tube type tires

2. The force of the momentum would have to be greater than the forces generated

generated by hard braking on a hard surface.

My perspective is sheared valve stems = under inflation.

 

[Doug Reid]

I looked at the flight manual....read all the checklists, but did not see any mention of this subject.

 

[Magman]

I looked at the flight manual....read all the checklists, but did not see any mention of this subject.

Constellation, B-25, or ??

 

[Craig]

Rotational inertia on gear wheels is a problem for most fast aircraft. My buddy Neil Anderson had to belly in the YF-16 at the first public demo due to not getting the wheels stopped prior to gear retraction. The spinning wheels caused the gear to slam into the locks and break one, jamming the door. Systems now apply the brakes and look for wheel rotation prior to gear retraction.

 

[Magman]

Is it possible that the reason for the placard is that the Connie had an early

version of a “ Auto-Braking System” as described previously? Maybe the system

would be defeated if manual braking were used?


The Connie and others existed in a time when new systems were being introduced.

Ignition/Engine Analysis, anti- skid brakes, and Auto -feather had to have roots

somewhere. As I re- read this again that time continues.

 

[Craig]

Found a copy of a C-121A flight manual. Using the brakes while the gear is in motion can cause damage to the retraction linkage crosshead. If the wheel rotation must be stopped, the brakes have to be applied prior to selecting gear up.

 

[Magman]

Now that makes sense to me.

Watching many Cessna main wheels shaking on take- off provides a

similar picture.

 

[Skip Miller]

Here is a cellphone quality photo of the Connie cockpit sitting outside the TWA Hotel at JFK. I see three lights low on the central pedistal, but beyond that I don't see what is being talked about here. Guess I will have to stop by the Connie on my next trip to JFK. -Skip

 

[Spring Ford]

This one seems to have that gear panel.

https://www.alamy.com/stock-photo-c...lockheed-super-constellation-or-56281317.html

 

[Magman]

Wonder if TCDS/Spec may have this as a required placard?