Bell 47 G2 Vs G3
 

Can anyone tell me if its worth having the G3 over G2 if flying in the UK at around 2000ft. Can anyone tell me the fuel burn on each. Thanks in anticipation.

If you are carrying three up on a hot summers day, even in Europe, the turbo charger on the G3 can be quite useful!

Does the G2, like the G3, have the high inertia main rotor blades? The HI blades made EOLs a real pleasure!

i don't think bell has ever made a low inertia blade! (on a 2 blade system...):}

The G2 does have low inertia blades & no where near the performance of a G3B1 or G3B2.

but in all seriousness, this is a pretty good article on the differences between 47 models:

http://www.bell47helicopterassociati...Rev.%20210.pdf

i only have time in a g2, and it would be alright for pilot and passsenger, though depending on the weight there isn't much reserve power for confined areas if you're full on fuel. pleasure to fly though, the manual throttle and low power teaches you to fly. for a private pleasure ship though the hydraulic collective of the g3 would sure be nice...it has a tendency to jump up or down during turbulence even with some friction on if you don't perfect the knee hook around it...

nigel,

i guess it depends on your definition of low inertia and whether it has the wooden or metal blades...i'd take either over a robbie though!:O

I only flew the D & G2 models with wooden blades ( looked like balsa wood inside!!) & were low inertia. The 3B1 & 2 had heavy metal blades & were incredibly easy to auto, even easier than the 206. Bell even produced a "blade bliveting kit" to attach on the blade tips so you could trim branches off trees!!

Hi Inertia???......
 

Loved the G5A and the G3B1 but the word inertia cannot be applied in any way shape or form to the venerable (Franklin engine) H1 that I had the dubious pleasure to fly on an air-test when it came in for maintenance. I think it was a 1956 model. The RFM advises a running take off and even illustrates the technique with the necessary sketches. See Restoring the Bell 47H-1

Yes the G5A and G3B1 has high inertia blades and such were their engine-off characteristics that my boss used to demo an EOL on to the pill-box on the southern edge of dear old Fairoaks. I was ne'er so brave but I could hit the target square just about every time. Great machine.

Had to do an EoL for real in a G5A with (Sir) Norman Foster when the newly furbished rotor head fooled the balance chappie and it threw off pitch so violently that we both thought the end of the world had come. Turned of the engine on the way down to a nice grass meadow. New underpants all-round.

G. :}

Interesting, Geoff! The H-1 has always been one of my favorite helicopters (it's even my desktop background). Too bad Bell made so few of them. Glad you got to fly one! I only got to ride in them as a kid; a NYC radio station for a time used *two* of them for traffic reports. But yes, with the Franklin engine they were doggy. I wonder if Bell instead had put in the high compression Lycoming VO-435 from the...?

As for differences between G-2 and G-3 as a personal ship, I'd take the wide-cabin turbo G-3 over the narrow-cabin non-turbo G-2 any day of the week.

Question for you, Geoff:

Why'd you shut off the engine? Was it giving you trouble? Did shutting it off help the vibration problem any?

Just curious. I've often heard pilots tell stories of having non-engine-related problems but entering auto anyway...just...you know...because. Which I never understood and still don't.

FH100
 

Why turn the engine off? Well we were at 1500 feet or so right above open farmland - grazing land so when the extremely violent loss of collective occurred I had no idea what had broken and I had no idea if I was going to be able to pull the collective up when I got to the bottom. I was pretty sure that we were heading for a real nasty and because the terrain was benign I got the engine stopped and the fuel turned off pretty quick. The safe landing that followed was an unexpected relief and once we had gathered ourselves I inspected I checked (G-BBRI) over and could find absolutely nothing wrong. I managed to convince myself that Norman had sat on the collective somehow even though he assured me it was ripped from his grasp.

On the way down I asked Norman to send a Mayday as I did not have a Tx button on the dual controls of this newly refurbished G5A. Norman - who was now as white as a sheet pushed his Tx button and said 'Mayday' - a man of few words.

I did a ground run and then a low hover and all was perfectly OK so I figured I was right about Norman sitting on the collective. He had a new PPL gained on our 206 but other helicopter chums told him he could never be a 'proper' chopper pilot unless and until he had a 'hand-throttle' machine on his license. Hence this training/nav flight from Elstree down to his Wiltshire pad.

There followed the most extraordinary exchange on the radio that had to be heard to be believed. When established at a comfortable cruise height I asked Norman to call London Information (we were working them outside the London Zone) and cancel our Mayday. The conversation went something like -
RI - London Information this is G-BBRI please cancel my Mayday.
A.N.Other - Silence on the frequency somebody is calling Mayday
RI. - No its me we want....
A.N.Other - QUIET I SAID there is somebody trying to send a Mayday
RI - This is RI we are ...
A.N.OTHER - SILENCE I SAID let the guy send his Mayday.
London Inf - G-RI go ahead
RI - Did you receive our Mayday call about 30 minutes ago?
London Inf - Negative
RI - Roger, we are now proceeding en route estimate...... bla bla bla

We got to a hilly part of Wiltshire whereupon despite both our hands being under the collective the same fault reoccurred, this time I left the engine running and landed on a sloping pasture close to a farmhouse. We left it there and I called the company and told them what I thought of their beautifully restored helicopter and that they had better send somebody to collect it as I had enough thank you very much.

Turned out that the teflon bearings in the head were so tight that when they set up the 'rabbits ears' (pitch balance weights) the tightness kept the blade pitch constant so it was never balance properly. When it threw off pitch it was so violent that every grain of dust plus our overnight bags (in front of the instrument console) hit the ceiling along with our arms and legs.

It was a memorable event - at least for me. Maybe Norman will put it in his memoirs, on the other hand .........

:}

G2 Vs G3
 

Having had the pleasure of flying all 47D,G and J versions, my favorite for any low DA ops which you are contemplating would be the G4A. The best version of the series ever IMHO.

G4A nicest from power point of view and no turbocharger to go phut. We had G2's & then G4A's. Hydraulic collective on G3's and up (except G5's) definitely nicer but oddly, the G2's seemed easier to do nice EOL's, notwithstanding the lower inertia blades. G2's ASI more truthful in autorotation compared to wide bubble types which over-read- ask me how I know!
I have recently flown a wooden bladed manual collective G model which had a nicely balanced collective, so it can be done but not on those with metal blades.

I've operated a G3B1(turbocharged version) on an aerial application contract. I'm a pilot/mechanic and on the flying side, yes, very nice helicopter to fly, actually I would say the 47 model is one of the nicest helicopters I've ever flown. The biggest issue I've had with the G3B1, on the maintenance side, is rigging the turbocharger. I was lucky because I had some old timers helping me but.....what a pain in the arse!! You would really need an engineer who has experience with rigging these things(and they are about as rare as rocking horse sh%t!!). Wastegate runs off of the aircraft hydraulic system for starters and you have this funky dual needle manifold pressure gauge that reads normally aspirated pressure and boosted pressure at the same time....and if you are doing a lot of power changes, those needles go all over the place! All depending you experience level, I've actually put myself in a couple of bad situations because my head was in the cockpit watching those damn needles dance around and hoping I still had cylinders when I landed. Also the turbocharger is the size of a toilet bowl on that thing which means you can overboost the hell out of your engine, EASILY! If I remember right, max manifold pressure is something like 49 or 54 inches(can't remember, its been a while), which means you can almost watch your cylinders land before you if you pull a bit too much collective. All that being said, once you get used to flying the G3.....she's the queen of the sky! And, with oxygen and a huge set of balls, you can take her up to max ceiling.....25000ft I believe:ooh:!!!!

As for the main rotor blades, on the bigger 47 models, Bell went to metal blades. If I remember right there are 3 versions of metal blades, the -13 which are short metal blades(not 100% sure on that, memory isn't what it used to be) and the -21 and -23, longer metal blades. The difference between the two(-21 and -23) is, the -23 has a 7 lbs weight in the tip of the blades which would make them "high inertia" blades and the -21 are exactly the same except with no weight. In fact, I think the -21 can be upgraded to a -23 blade just by installing the weight. I don't think Bell has ever called them "high inertia" blades but I can tell you that they will take FOR EVER to spool down after you shut down. I've actually seen this done by our chief pilot at the time(and I think it was one of the selling points by Bell when they first came out with the -23), in a hovering auto, land, pick it back up, turn 180 degrees and land again. Quite impressive blades.

But don't think for an instant that the -21 blades are "low Inertia" and your going to sink like an r22. Actually I've done a few autos with a G2 with wooden blades and, yes, things come at you a bit faster, but its by no means like an R22 or 300 auto.
In my opinion, a G2 would be a great little heli to have fun with and if you really are looking for a wide cabin and a bit more power, go with a G4 or G5 NON turbocharged ship.

There is my 2 cents.
Be safe
GV

the bell g2 and the g3 both had metal blades, the difference was that all the turbo models had tip weighted blades to maintain the inertia in normal flight to cover the lag in the turbo charger.

we tried tip weighted blades on normally aspirated 47's but they were a bit harder to handle rpm wise so we took the tip weights out.

most turbo 47's have had the turbo removed and high compression pistons installed. you wont notice much performance difference unless you wan to operate at high altitudes, makes no difference at sea level.

Imabell, if you remove the turbo are you saying that you need to install high compression pistons?. I'm just trying to decide between the 2 machines for private 70 hours per year flying and don't want to pay the extra in fuel and complexity for a G3 if flying at 2000ft in the uk won't see any performance increase. Whats your view? thanks for the info so far.

valve guide,
I always thought that a G3B was a narrow bubble machine with turbo?? different from the 3B1, 3B2 and 3B2A, which with the A models of the 2, 4 & 5 variants were all wide bubble. but the straight number was a narrow bubble.

The G2 / G2A, either metal or wooden blades were quite a bit shorter than all later metal blades which were uniform in length. The weighted tip on the turbo machines was also to accomodate the higher allowed AUW.

I think you will find that the EO to remove the turbo and ancillary gear (about 80 pounds weight) will also include instruction to replace the low dome pistons with the high dome /higher compression ratio ones.
This is handy as the longer blades take a bit more power to wind up than the shorter ones but once wound up are far more efficient than the shorter ones. gives you an extra 40-45 ponies.

So the G3B / 2A-1 will be the G3B1 with turbo removed, three power cylinders, heavy sparks box and still 24 volts.

Turbos can be removed from the KH4 except of course they already had the non weighted blades.

The normal G2 were fitted with a light weight freewheel --ugh ugh ugh -- the G5, 3B, 3B1 and straight 4 had medium weight and the 3B2A, 3B2 and 4A all have the heavy weight with the 900 series xmon. do yourself a favour if you remove the turbo get yourself a heavy weight free wheel which can be put on a 600 series xmon.

If you can still buy a Texas no bar kit you will get rid of the 30 pound stabilizer bar and of course the power required to wind it up. Makes them quite touchy to drive, be sure your irreversible valves and power cylinder bushes are not worn out or they become - real - touchy.

If you really want to lighten it up more you could look at a Jasco alternator and shed the heavy generator and ugly heavy, bastard turnout, sparks box.

which ever way you go you will enjoy it as long as you don't short cut on the horsepower.
cheers tet

47 choice
 

Hi valve guide,
I have had a few different models of 47 over the years. Have just changed my 3 B1 for a G5.
3B1 was good machine apart from 5 minute warm up and shut down, as opposed to 3 mins on G5. Turbo certainly uses more fuel and should you need to have it o/hauled or fixed, good luck !
A good 435 engine should give you plenty power in this country.

As for fuel consumption, I stick my head in the sand, as if I knew exactly how many litres per hour I was chewing thru, the smile that goes with 47 flying, would not be quite so wide !

De-turbo'ing 3B1 has been done in UK before, on the 47 for sale at Heli-Air, so should be ok as far as CAA is concerned. Good luck. :ok:

Faith - a definition!!
 

NMPKT (Not Many People Know This)

But in the late '70s we were patrolling the skies above London in a G5A and then a G3B1 on contract to the Met Police. I have a great snap taken overhead Big Ben at 200 feet whilst policing a protest march - taken through the bottom of the bubble.

Those were the days!

Heaven knows what would have happened if the donkey decided to wrap its hand in.

On one occasion an illegal Heathrow overflight by a light FW caused a panic and we were asked to chase it. The ripples of laughter cause a temporary loss of decorum. With a Vmax of 90 knots we weren't going to chase very much. Even traffic pursuits were challenging, especially into wind.

The best tip I can suggest is chose your police observer carefully - two of you over 6'4" and life gets to be 'interesting'.

G.

for the normally aspirated, a good tip to look after your endurance is to operate just below where the power jet opens up at around 22.5".

as long as the machine is rigged as per the book and M/R balanced really smooth it will only be around 3 to 4 knots difference between that and max cont (24.7").

but it equates to around five to six litres per hour saving.

if you wish to operate a wet sump engine (VO 435) make sure that you check the surrounds of the idler gear shaft on the accessory gearbox every day for any evidence of oil seepage. That will indicate wear on the shaft or housing and I can virtuially gaurantee that it will fail within 25 hours of first evidence.

failure gaurantees one cough then silence. BTDTx2

it is the reason why there are no more 3B2A's around much anymore they being a turboed wet sump engine.

This is all great advice so please keep it coming!