Chuck Aarons BO-105 HELP

[offthedirt]

Hey everybody!
I've lurked these forums for a few years now here and there, but I finally have a question that I need direct help with. Let me apologize now if this has been covered already. I've searched through here and any other source I can find, to no avail. I'm currently working on my Private rating at Leading Edge Aviation through Central Oregon Community College. A few of my classes have us prepare and give speeches on topics of our choosing. Here's where I might have made a mistake. For one of my courses I decided to write on the Red Bull helicopter. I'm fascinated by it so I figured it would be something fun to write. While I can find more than enough information on Chuck Aaron and the BO105, I cant seem to find anything on the modifications he's done to his aircraft. One article I found said it was a guarded secrete of his. I've also heard, including my instructor after asking him about this this morning, that he really hasn't done much to it and that a standard BO105 is capable of performing such maneuvers (which I'm not fully buying). Like I've said, I've searched high and low for information on them, so unless I'm missing something I might have to just cut sling load and move on to another topic. Any and all information, resources, and even advice would be GREATLY appreciated. Thank you for your time.

[Flying Pig]

There are not going to be any secret mods. Anything he would do to it would have been approved by the FAA, which would all be public record. The BO105 is a pretty amazing machine.

[adam32]

There are not going to be any secret mods. Anything he would do to it would have been approved by the FAA, which would all be public record. The BO105 is a pretty amazing machine.

 

That's not necessarily true, I don't believe Experimental aircraft need to report mods to the FAA? I could be wrong on that tho.

 

I do know his BO105 has extensive fuel system modifications. Other then that is anyones guess...

[eagle5]

If you look really, really closely at it you'll see that its actually just an r22 painted red!

[apacheguy]

I think the big secret is that he pulls a crapload of maintenance on it before and after every flight. Plus he's a helluva good pilot.

[Jaybee]

I believe the rotor head is made of titanium.

[Wally]

Saw a video once discussing some of the changes, showed some tankage in the aft cabin, visible through the clamshell doors. I want to say I remember these as part of a special fuel and oil supply for reduced/negative G.

[Falko]

He mentioned in an interview that he moved the CG further back. I have been to air shows in Europe and saw couple military Bo105 flying even more aggressive maneuvers then Aaron does. Don't get me wrong he is a good pilot but he isn't really pushing the limits of the Bo105.

 

Watch some videos or Reiner Wilke or charly Zimmerman, who actually died in a 105 during a sells pitch..... after watching them you will understand my point

[RagMan]

Just because you can, doesn't mean you should!

[apacheguy]

I believe the rotor head is made of titanium.

 

The EC145 has a rotor head machined out of a monolithic block of titanium (about 2' x 2' by 1.5'). I can only imagine how much a chunk of titanium that big must cost. Not sure about the BO105 or BK117.

[helipilotm]

A few other mods I've heard about besides what's been said, change of CG, Fuel system, rotor head is engine, gearbox mount changes and the gearboxes lube systems changed somehow so theres always oil flowing also I wanna say he had a whole new T/R gearbox made but not 100% sure. My boss who is also a mechanic talked to him at an airshow once. He obviously didn't go into too much detail but told him the basics. All I have to say is I'm glad it's him and not me

Edited February 13, 2015 by helipilotm

[Spike]

Mr. Arron was one of the presenters at last year’s HeliExpo FIRC. He spent about an hour discussing many aspects of what he does. From what I recall, his machine is highly modified and considered proprietary since he did all of the engineering and modifications himself (which took a significant amount of time and money and hence the reason why his mods are proprietary). …..

 

Either way, Mr. Aaron was extremely approachable and helpful. A genuinely nice guy in fact. If you can get his contact info, I’m sure he’d answer any of your questions short of the secret squirrel stuff…….

Edited February 13, 2015 by Spike

[iChris]

I cant seem to find anything on the modifications he's done to his aircraft. One article I found said it was a guarded secrete of his. I've also heard, including my instructor after asking him about this this morning, that he really hasn't done much to it and that a standard BO105 is capable of performing such maneuvers (which I'm not fully buying).

 

Helicopters can do loops and rolls; however, there’s a coupe of main issues to take into account.

 

The first issue is the problem with respect to control at the top of the loop, where the rotor thrust is zero or very low. All helicopters have reduced control power in pitch and roll, and some; those with teetering rotors may have none at all. If the pilot wants to make a cyclic correction in this situation, it would require an extraordinary amount of cyclic movement than normal to get a control response. This is the classic set-up for mast bumping on teetering rotors and for droop stop pounding on fully articulated rotors.

 

However, this issue is reduced with helicopter with high offset rotors, like the BO-105. High offset rotor systems have increased control power. High offset meaning the increased distance between the rotor mast and flapping hinge or virtual hinge on a hingeless rotor.

 

The second issue is trying to keep the engine from knowing its not right side up. We need to look at the fuel and oil system. Fuel and oil must be able to reach the engine in any attitude the pilot puts the aircraft in. Even for the brief periods the helicopter is looped and rolled. Look up aerobatic aircraft, inverted fuel and oil systems. We also need to consider hydraulic systems and how to keep the fluids moving.

 

The engines are often removed and ran on a test stand in an inverted position to ensure their performance. Thereafter, modifications are incorporated as needed.

 

Can a helicopter do steady inverted flight; theoretically, yes, practically, no.

 

A rotor could produce enough negative thrust to support the helicopter’s weight inverted if it were designed with enough negative collective pitch range. Some radio-controlled helicopter models have illustrated this possibility. No actual helicopters are rigged in this manner for two reasons:

 

1. It would require a collective-control system with twice the normal travel and thus would require more space and weight than a normal system; and

 

2. It would lose the important safety feature of having the down collective stop approximately corresponding to the right position for autorotation.

 

Several Sikorsky helicopters, including the tiny S-52 in 1949 and the giant CH-53A in 1968, have done documented loops. One aircraft that did them routinely at air shows was the original Sikorsky S-67 Blackhawk an attack version of the S-61 built on speculation during the Vietnam War as an alternative to the Lockheed AH-56A Cheyenne.

 

Given enough motivation, designers and pilots can develop impressive capability in the field of aerobatics. I’m sure that BO-105 has undergone many improvements and incorporated many new ideas as a result of their teams learning curve, trial and error, and things discovered.

 

In a paper written for the American Helicopter Society (AHS), the Sikorsky flight-test engineer explains how the maneuver was done in the Sikorsky S-67 Blackhawk:

 

The loop is initiated from a slight dive at approximately 175 knots. The cyclic is pulled aft and collective lowered slightly to limit control loads. As the aircraft passes the 90° point (going straight up), collective is added to maintain positive G. Airspeed at the inverted point in the maneuver averages 50 knots. The average time to execute a loop is 21 seconds. The load-factor range for the maneuver runs from 2.5 plus G at the entry to 0.7 G inverted to 2.5 plus G during the recovery.”

 

The roll maneuver is conducted only to the right to eliminate the problem of interference between the collective stick, the pilot’s leg, and the cyclic stick. Generally, the maneuver is started from 150 knots in level flight. The aircraft is pulled to 20° noseup and the pitch rate is reduced to a minimum. As the airspeed reaches 130 knots, full right and a slight amount of aft cyclic are introduced. As the aircraft reaches the 270° point (three fourths of the way through the roll), lateral cyclic is returned to neutral and additional aft cyclic is introduced to counteract the nose tucking which initiates at approximately the 270° point. The aircraft generally exits the roll at level attitude. The roll takes an average of six seconds to complete and the load factor ranges from 0.8 G to 1.7 G for the maneuver.”

 

The split S turn consists of the first half of a roll to get inverted and then a recovery like the second half of a loop. The entry is made at approximately 70 knots. Higher speeds were investigated but were found unacceptable due to excessive speed buildup when the nose is pointed straight down. The maneuver is initiated by introducing full right cyclic stick. When the aircraft is inverted, the roll is stopped, a slight increase in collective is introduced to maintain positive G, and the cyclic is brought aft. The recovery is a standard symmetrical pullout using cyclic only. The collective is held fixed or lowered slightly depending on the load factor demanded. The load-factor range for the total maneuver can run from 0.5 G in the inverted position to 2.5 plus G in the recovery.”

Edited February 24, 2015 by iChris

[offthedirt]

iChris, thank you for the info! Definitely some key talking points I cant use during my speech!

[offthedirt]

Didn't see the other posts at first. I appreciate all of your answers! Thank you! Spike, I was considering doing that and have only really heard good things about him. It's definitely worth a shot!

[Guest pokey]

Chris, i'm sure you did not mean to say that inverted fuel and oil systems are required for aerobatic flight (including loops and rolls), as both of these are positive G maneuvers. Now "sustained" inverted flight?-yes, both are required. Here is link of a 53, long B4 red bull.

 

http://allthingsaero.com/military-aviation/helicopters/video-before-red-bull-looped-the-ch-53-could-do-just-the-same

[adam32]

300's have looped, Lynx does, even a 407 has looped...once.

[Goldy]

I would just ask him yourself. He's not going to say a whole lot, he does NOT want anyone to try this at home!

 

He is really easy to find, but if you need his email address, send me a PM.

[iChris]

Chris, i'm sure you did not mean to say that inverted fuel and oil systems are required for aerobatic flight (including loops and rolls), as both of these are positive G maneuvers. Now "sustained" inverted flight?-yes, both are required. Here is link of a 53, long B4 red bull.

 

http://allthingsaero.com/military-aviation/helicopters/video-before-red-bull-looped-the-ch-53-could-do-just-the-same

 

Some type of provision should be made to ensure continuous fuel and oil flow, even if not theoretically required.

 

As far as standard helicopter systems are concerned, most engine and fuel systems are not designed to maintain proper fuel and oil flows during an extended aerobatic regime. If you’re out week after week doing show aerobatics in the public forum, you need to ensure an increase degree of safety.

 

Theoretically, if a positive G load is maintained, there should not be an interruption in fuel or oil flow. However, if the helicopter reaches 0.5G - 0G or below and positive 1G load is not restored in a few seconds, fuel or oil starvation could result in engine shutdown or internal failure.

 

The BO-105’s G load limitations are -1.0G to +3.1G along with an effective main rotor hinge offset ratio of .14 (14%). The average helicopter hinge offset is .05 (5%) or less. With that type of control power, very large and abrupt changes in attitude and G load are possible. What’s the condition of your fuel and oil during these types of maneuvers? As a precaution, if not already installed, at minimum a pressurized fuel and oil system to ensure uninterrupted fuel and oil flow.

 

Example, Some engine have listed limitations. Example the Turomeca Maintenance Manual, ARRIEL 1B engine:

 

Some engine have stated limitations. Example, the Turomeca Maintenance Manual, ARRIEL 1B engine:

 

Edited March 10, 2015 by iChris