Rare Bear Propeller Question

[RBriscoe]

The Rare Bear reportedly uses a 13 1/2 foot propeller from a US Navy P-3 Orion. Has anyone heard if the team ever evaluated the six bladed propeller from a C-130J, which has a similar diameter, or the eight bladed propeller (Hamilton Sunstrand NP2000) which was introduced by the US Navy on the E-2C and C2 as a replacement for the existing four bladed propellers (which were in short supply and the tooling no longer existed)? These same NP2000 propellers have been used by commercial air Snow Aviation on some C-130s and the USAF has tested them for an upgrade to the "Legacy" C-130s.

The Navy reported increased thrust and reduced vibration compared to the propeller it replaced and the Air Force has reportedly concluded that they increase the thrust of the existing engines to roughly that of a JATO assisted takeoff (the first USAF user is apparently the New York ANG unit that uses the LC-130 for Antartic resupply missions).

The C-130J propeller apparently has the same diameter as the P-3 propeller and the NP2000 propeller must be of a similar diameter although I have not been able to find its exact diameter. The NP2000 reportedly has not had problems with some of the airflow issues reported to have occurred with the C-130J.

This would appear to be a possible way for the Bear to increase thrust with the existing engine.

Anyway, I just wanted to ask if anybody had heard anything one way or the other.

Cheers

P.S. In case you are not aware, the Blue Angels discontinued the use of JATO assisted takeoffs for Fat Albert some time back due the the short supply of bottles which are of Vietnam era manufacture. I have not heard of any plans to resume production of the JATO bottles.

[Race5]

Re: Rare Bear Propeller Question

The Rare Bear reportedly uses a 13 1/2 foot propeller from a US Navy P-3 Orion. Has anyone heard if the team ever evaluated the six bladed propeller from a C-130J, which has a similar diameter, or the eight bladed propeller (Hamilton Sunstrand NP2000) which was introduced by the US Navy on the E-2C and C2 as a replacement for the existing four bladed propellers (which were in short supply and the tooling no longer existed)? These same NP2000 propellers have been used by commercial air Snow Aviation on some C-130s and the USAF has tested them for an upgrade to the "Legacy" C-130s.

The Navy reported increased thrust and reduced vibration compared to the propeller it replaced and the Air Force has reportedly concluded that they increase the thrust of the existing engines to roughly that of a JATO assisted takeoff (the first USAF user is apparently the New York ANG unit that uses the LC-130 for Antartic resupply missions).

The C-130J propeller apparently has the same diameter as the P-3 propeller and the NP2000 propeller must be of a similar diameter although I have not been able to find its exact diameter. The NP2000 reportedly has not had problems with some of the airflow issues reported to have occurred with the C-130J.

This would appear to be a possible way for the Bear to increase thrust with the existing engine.

Anyway, I just wanted to ask if anybody had heard anything one way or the other.

Cheers

P.S. In case you are not aware, the Blue Angels discontinued the use of JATO assisted takeoffs for Fat Albert some time back due the the short supply of bottles which are of Vietnam era manufacture. I have not heard of any plans to resume production of the JATO bottles.

The Bear hasn't used the P-3 based three blade prop in may years. The four blade Skyraider based prop has proven to be faster at Reno.

[RBriscoe]

Re: Rare Bear Propeller Question

The Bear hasn't used the P-3 based three blade prop in may years. The four blade Skyraider based prop has proven to be faster at Reno.

Thanks for the update. Are you aware of the team evaluating other propellers?

[Big_Jim]

Re: Rare Bear Propeller Question

The late-model prop blades for the C-130 were developed for cruise efficency not muscle and speed. And I doubt in 1988-89 that they were available for civil use--at least within FBDoR's checkbook depth.

That's just a LOT of mass whirring around up front...the reason they went to three blades instead of taking the entire four-blade setup.

[RBriscoe]

Re: Rare Bear Propeller Question

Big_Jim,

"A lot of mass." That's quite true, even with the CF construction. I have no idea what the weight/mass of a blade for the new prop for the LC-130 might be and it is certainly true that the rotating mass (and torque) is less of an issue for a E-2C or C-130 size aircraft than an aircraft the size of the Bear. Nevertheless, it is true that there is a good bit of torque on a C-130.

During the Iran-Contra era, there was a C-130 which crashed at Kelly AFB which was an alphabet employer mission with a less than stellar aircrew who failed to remove the wood stick (used to keep the control surfaces from flopping around in the breeze when parked) during the preflight. They also failed to run control checks during the preflight which would have revealed that the flight controls were jammed. The net result was that the aircraft did a torque roll on takeoff crashing into the front of a hangar on the flight line.

The testing on the LC-130 dealt with thrust. Although there are definitely cruise benefits, the takeoff thrust enables the aircraft to take off in circumstances where a JATO takeoff was previously required either without JATO or with fewer bottles.

I guess the question would be a matter of which blade design is more efficient (scimitar vs. paddle) blade for blade with a balancing of total mass/torque to determine the number of blades which could be used efficiently within those constraints.

Cheers

[Dialtapper]

Re: Rare Bear Propeller Question

During the Iran-Contra era, there was a C-130 which crashed at Kelly AFB which was an alphabet employer mission with a less than stellar aircrew who failed to remove the wood stick (used to keep the control surfaces from flopping around in the breeze when parked) during the preflight. They also failed to run control checks during the preflight which would have revealed that the flight controls were jammed. The net result was that the aircraft did a torque roll on takeoff crashing into the front of a hangar on the flight line.

As anyone who knows me would attest to, I'm far more honest than tactful.

But you Sir, are an idiot. Only a true idiot would state total BS like it was fact.

1, "alphabet employer mission"?
Have no idea what your talking about, but then you don't either. It was a standard Log Air trip. (AFB to AFB contracted by civilians flying cargo for the DoD, scheduled 7 days a week, 365 days a year.)

2, "less than stellar aircrew"
Class act to slam dead people.

3, There was no "wood stick".
There was a metal control lock.

4, "to keep the control surfaces from flopping around in the breeze when parked"
Please, where talking about a C-130 with hydraulic controls, not a Cessna 150. The purpose the control lock was to fair the elevator with the horizontal stabilizer, to lessen the chance cargo loaders hitting it.

5, "They also failed to run control checks during the preflight"
Control checks where done and normal. The control lock was removed, but stored in the improper place, and fell out on rotation.

6, "aircraft did a torque roll on takeoff"
The aircraft pitched up and did a hammerhead stall.

It did end up hitting a hangar, in front of Base Ops.
I was there a day after, lost two good friends and a class mate. Two good friends I had flown with a couple of days prior. I also spent a week in Miami where I testified during the trial.

Sorry, but hate to see friends who are no longer here put down by someone that doesn't know what there talking about.

Back to a thread about props.................

[AAFO_WSagar]

Re: Rare Bear Propeller Question

Back to a thread about props.................

Chris... I love your ability to manipulate the English language with subtlety and grace....

[RBriscoe]

Re: Rare Bear Propeller Question

As anyone who knows me would attest to, I'm far more honest than tactful.

But you Sir, are an idiot. Only a true idiot would state total BS like it was fact.

1, "alphabet employer mission"?
Have no idea what your talking about, but then you don't either. It was a standard Log Air trip. (AFB to AFB contracted by civilians flying cargo for the DoD, scheduled 7 days a week, 365 days a year.)

2, "less than stellar aircrew"
Class act to slam dead people.

3, There was no "wood stick".
There was a metal control lock.

4, "to keep the control surfaces from flopping around in the breeze when parked"
Please, where talking about a C-130 with hydraulic controls, not a Cessna 150. The purpose the control lock was to fair the elevator with the horizontal stabilizer, to lessen the chance cargo loaders hitting it.

5, "They also failed to run control checks during the preflight"
Control checks where done and normal. The control lock was removed, but stored in the improper place, and fell out on rotation.

6, "aircraft did a torque roll on takeoff"
The aircraft pitched up and did a hammerhead stall.

It did end up hitting a hangar, in front of Base Ops.
I was there a day after, lost two good friends and a class mate. Two good friends I had flown with a couple of days prior. I also spent a week in Miami where I testified during the trial.

Sorry, but hate to see friends who are no longer here put down by someone that doesn't know what there talking about.

Back to a thread about props.................

I, sir, am not going to engage in name calling.

I am sorry that you lost friends in that mishap.

Nevertheless, you are mistaken about the most basic facts of the incident. The failure of the mishap aircrew to properly preflight the aircraft. Whether the wood stick (as reported locally) was in fact a piece of metal does not change the fact that the aircrew failed to remove it or failed to verify that it had been removed and test the flight control surfaces were fully operational is an essential, if basic, part of flight operations.

If you do not know the true nature of the mission, will simply leave that matter alone.

Now back to propellers.

[AAFO_WSagar]

Re: Rare Bear Propeller Question

If you do not know the true nature of the mission, will simply leave that matter alone.

Richard, I truly appreciate your decision not to "spar" with DT... I consider you both friends and don't like to see friends "argue"...

That said... if you, I DT and everyone else here on the board were in a hangar shooting the breeze and tipping cold adult beverages, Chris would say the same thing right to your face and, trust me.... it would not make you mad.. You would just know that DT was being square with you..

Something you should know about DT.. he's flown cargo for... companies which contract with the military to haul goods for many, many many years... worked for the airline in question and does know of what he speaks..

He's also one of the very talented Reno Air Race crew members and a valued visitor to this site.. You'll find that aircrew, tend to be pretty blunt.. SO... with that said... ... well... that's said...

Back to props!

["Bear" Driver]

Re: Rare Bear Propeller Question

[QUOTE=The four blade Skyraider based prop has proven to be faster at Reno.[/QUOTE]

Better check your history....
JCP

[Leo]

Re: Rare Bear Propeller Question

Bear Driver, Did the 3-blade give it some "different" flight dynamics? I read somewhere it affected the way it flew, would sure appreciate hearing about it from the source!

[flyingjibus]

Re: Rare Bear Propeller Question

Better check your history....
JCP

HAHAHA.

I was going to post something along these lines, but you are a much better voice!

The Skyraider prop was found to be more stable I would say, but certainly not faster.

[Dialtapper]

Re: Rare Bear Propeller Question

Chris... I love your ability to manipulate the English language with subtlety and grace....

"Subtlety and grace" Ya, that's me. I happy to see all I learned from Ms. Manners correspondence charm school is evident. I thought it might have been a wast of time.

I think the problem is when people believe what is "as reported locally" as being fact. It so seldom is. Just look at Reno last year.

Now lets hear more from Bear Driver, that I will take as fact.

[Tigercat24]

Re: Rare Bear Propeller Question

I did here somewhere that the 3-bladed prop may have been faster, but because the blades themselves were so wide, the bursts of air that the blades sent back buffeted the airframe too much at speed. The 4-blade Skyraider prop reportedly chosen for high speed stability, allowing for the pilot to focus on racing rather than keeping the Bear from doing something crazy...any more than he would have to anyway.

[DOC.129]

Re: Rare Bear Propeller Question

Better check your history....
JCP

Was in the Bear hangar the other day and was told you guys are taking a crack at the 3K soon. Who's going to fly her?

Brian