Bell UH-1

[bomber]

Next question, you might be able to answer.

Typically how many universal joints in the tail rotor drive-chain.

I'm trying to work out it's efficiency.

So far I have this

gear box efficiency = 0.941
3 universal joints at 0.99
Angular take-off efficiency = 0.931

regards

Simon

[bell_pilot]

As i know, universal joints are used only in 42 degree gearbox. But i dont know the exact quantity.

[bomber]

Ok located that info here

https://www.quora.com/How-does-a-helico ... rotor-head

3 support bearings and 2 bevel gearboxes

also given me speed of tail rotor rpm.

[edit] oh wow I just found out the tail drive shaft is at 40,863 RPM... with the two bevel gearboxes reducing this down.

I guess it's run at this RPM to lower the torque on the shaft and thus keeping it's construction weight down

[bell_pilot]

I am waiting for the updated model

[bomber]

A lot of spanners got thrown into the machinery it's taking time to understand all the implications. And my understanding changes on a daily basis... Yesterday I thought the RPM of the tail rotor shaft was for torque, but after last nights work my thoughts are it's actually to ensure the rpm's of the tail rotor are effected as little as possible by the hunting of the turbine governor. This being important to prevent 'fish tailing' with fluctuation of load from the main rotor on the turbine.

So hopefully if I resolve this and do some FCS updates there should be a release by the end of the week.... but you never know.

Simon

[bell_pilot]

E.g:
If you press left pedal instantly hard, rpm falls, both for Huey and Whiskey.

[bomber]

Yes that would make sense, but it''s effect on the main rotor rpm's should be minimal.

There is however rpm variations of the main rotor caused by it's governor 'hunting' the rpm's around the 324 value. My code used this value to govern the tail rotor rpm, which because of the increase in rpm's of the tail rotor means any error in the main rotor is magnified into the tail rotor rpm.... this is wrong. I have to rewrite the code such that the turbines larger rpm's are used and the hunting errors are reduced into the smaller value tail rotor rpm.

Shouldn't be too hard to do.

[bomber]

https://forum.flightgear.org/viewtopic.php?f=17&t=38762

I think this is an interesting topic, especially for helicopters, where glancing at the gauges repeatedly is needed, and you don't really want to move the view cause a lots happening.

I think I'd like a single key press to call this up and an automatic fade away.

[bell_pilot]

Yes that would make sense, but it''s effect on the main rotor rpm's should be minimal.

Consider that both drive-shafts of the main rotor and the tail rotor are powered by same transmission.
Sudden increase AoA of tail rotor peaks the power-needed to overcome profile drag. This causes to drop of the main rotor rpm for a moment too.

[IAHM-COL]

Not that I want to add to pressing time, but I am eager to test the output of bombers machine, also

Take your time. I learned to sit on the sidelines, even more when the only contribution I can make is that of the cheerleader. And I wear Jeans.

Best,