Having had the sheer pleasure of flying BO' and BK's.....and the occasion to be left alone to my temptations.....I could never bring myself to roll or loop them.....I always chickened out first.

Far too many years of flying Bell Products I suppose.

Sikorsky 53's and 97's used to do those maneuvers and some have been on video.

A Bristow 58T went inverted coming off a Platform one night (based upon the Cabin Attendant's comment about walking on the overhead)...and the Pilot not knowing the actual attitude of the aircraft....but the Pitch Change Link knuckles on the Swash Plate gave evidence to the Jury to confirm something interesting happened.

The head was titanium, the mast steel.

My question is on the fuel system.
I cannot see how the standard system would work in any prolonged negative G or inverted flight.

You can be inverted, briefly, without negative g and he doesn't fly it along upside down like a fixed wing could.

Someone asked a question earlier in the thread about why he rolls left - ISTR the Germans lost a few 105s early on because, like the Lynx, there is a pronounced pitch/roll couple to the right.

This is noticeable when performing back flips and loops and can be demonstrated in a steep turn to the right. Opposite cyclic is needed to stop it rolling further.

I suspect therefore that he does the rolls to the left to give the best control margin for recovery.

On the other hand it may be to reduce the twisting loads on the tail boom/TR.

If I remember right, somebody told me, could have been Rainer Wilke, that there are two small feeder tanks close to the engine which solve that problem.
I asked Rainer how he does his very tight rolls - not the barrel rolls - without loosing altitude, well he does, he is flying kind of an arc and is falling down. There is the zero g. The upside down pedal turn would also be zero g or low negative g (actually wouldn't that be high, since it is negative). And it never lasts for very long, since you can not have negative pitch.

In the 105 the feeder tank that can be one or two compartment is located under the passenger cabin floor.
Booster pumps are mounted on the tank floor.
Seems to me that the standard system would be prone to sucking air if the aircraft enterred zero G.
I recollect that minimum pitch on the 105 is 4 degrees 15 min. Interesting effects if you rig it to less!!!!

I have looked at one of the many displays on YT, and I'm not convinced there is any negative g. Being upside down doesn't mean you have to be zero or negative. Apart from early FW Aerobatics, I spent some time in 2001 with the Eurocopter Flight Test Dept pilots looking at the EC155, and a couple of manouevres they demonstrated, and I subsequently flew, were a) slow down to less than 40 KIAS in level flight, then roll inverted and pull through, and b) bunt 90 degrees nose down, then roll 180 degrees and pull through. Neither was anything less than positive g throughout, although short periods of less than 1 g.

Agreed 212 man:ok:

I’ve been out of touch on this sort of detail, but US military helos test specs for the structural demonstration series of maneuvers always included demo to -0.5 G*. ( and no, I don’t know how the Bell guys accomplished this data point with a teetering rotor,, but God bless ‘em, they must have found a way )
For the US Army UTTAS competition the Boeing and Sikorsky competitors had an additional maneuver requirement added, which in part required holding 0.0 G for two seconds.
*As measured at the aircraft center of gravity, thus the cockpit Nz would be lower ( due to the pitch rate ) esp. in larger machines.

you do not need negative pitch to get negative G.
Just push the cyclic stick slightly forward. The same is valid for Reiner Wilkes nice rolls.

Negative G on the Bo105 will cause the engine oil pressure to go to zero immediately. From my memory the MGB was not affected like this.

The feeder tank is always full as long as there is fuel in the main tank, with the surplus from the transfer fuel pumps flow poring back into the main tank. There is no time limit for the negative G for fuel purpose but the total time on the minus side will nit be long.

Was Charly Zimmerman the start of the BO-105 aerobatic flying?


https://www.youtube.com/watch?v=93zy3OqXMPw




https://www.youtube.com/watch?v=WSQ_-SB0gVQ

SAS, I think the origination started with Siegfried Hoffman, a test pilot at MBB. By 1982 at the Hanover airshow, world aerobatic ( helicopters ) champion Hauptman Karl Zimmerman* was doing the most impressive and choreographed aerobatic displays in the BO-105. Had the pleasure of watching him daily, and then giving he, his spouse and children a ride in our UH-60A, chaperoned by Sergei Sikorsky. Siegfried Hoffman was also there,with his new BK-117 ( with SAS, no less ) and was invited to trade rides with him. ( having done a flight evaluation of the BO-105 in the days prior to the UTTAS fly-off, the BK was certainly a step forward, not to take anything away from the maneuver capability of the 105 in the right hands ).
*Karl told us that back in his anti-tank helicopter unit he practiced the aerobatics daily, and his show certainly reflected that resulting excellence.

As Chuck Aaron ably demonstrates here (go to 33:00 min)

However, here is a clip with pilot Rainer Wilke where (very occasionally) the wig of his passenger flies up under negative G (check 6:15 min)

EVERY BO105 is capable of these manoevers…

His mention of Bob Hoover......

No you need a lot more than that for negative g.

You can get a slight reduction from purely forward cyclic but for negative you need a zoom climb followed by a bunt - ie lower the lever a bit as you push the cyclic forward.

Most engines and gearboxes can cope with that for short periods.

So as we probably all know, Chick talks a good fight but didn't invent the manoeuvres, teach himself them nor modify the aircraft in the ways he clamed.

Not saying he is a bad pilot just a self-promoter.

You dont need a zoom climb for that. It can be a good idea if you like to have room for a longer negative G (well, less short anyway).

For the negative G part, if you have speed just push the stick forward. And before you do it, secure any loose object and clean the floor from things otherways will hit the roof.
The standard in the handheld GPS times was surplus batteries put in some opening in the frame caming loose and flying around in the cockpit before they first stuck in the roof and then fell down to the floor when getting positive G again.

Yup. We had the -1G limit but no set time limit for that, just the natural limitation that it would not last for long time anyway.


Exactly!

Some of the talking about very advanced modification (” changing the CoG”) involved moving the battery to the position that I think most military BO105 already had.

He was trained by Rainer Wilke, as was the other 3 current Red Bull BO105 display pilots including Aaron Fitzgerald.... But it is always great to take the credit.....

Is there any news about the alleged tail rotor failure which led to the restart of this thread after 4 years?

Watched him perform in 1998 (at the age of 76!!) a year before he retired from displaying. Same display as in the clip, minus the ice-tea part... A true master!

As usual with the capabilities of the 105 everybody focuses on the the Main Rotor and forgets about the poor old tail rotor.

Every helicopter has it's weakest point and the T/R on this model and the 117 has it's issues along with it's mounting points and mechanisms.

The head is the least of your problems as it is basically the same used right up to the H145D2 except the internals are a bit heavier, thats all.