Old Hirobo Bell 47

[electricsceadu]

its looking good pete
i think the vario bubble fits the mk1
the mk2 hirobo bubble is available to order from ripmax

with the tail my 1st mk2 has a poor tail but my 2nd one has longer tail blades and the tail is great, so it may be worth trying longer tail blades on the mk1

if its like the mk2
if stood for a while,fuel up, remove the plug, pull the engine over a few times, replace the plug and put the choke on
now pull over until it coughs and splutters
turn the chkoe off and it will fire up

and a picture of my back up bell 47

[pchristy]

Looks good! I notice the Mk2 has the "Tsurugi" head! The Mk1 has a metal head and blade grips. I'm a bit dubious about putting carbon blades on there. They are so rigid, I can foresee a metal fatigue problem in the blade grips. The woodies on it are fine, but they seem pretty light - I'm not sure how well it would cope with a flame out!

Thanks for the tip about the Vario bubble! That's another source to try! I've still got a bit of work to do on the mechanics / radio yet, but its almost there, and then I can start on the cosmetics!

I was pleasantly surprised to find it wasn't under-powered! There have been a lot of negative comments about the old Hirobo engines. Denis Stretton reckons the timing is critical, and needs setting up very carefully. Whoever set this one up clearly knew what he / she was doing!

8-)

--
Pete

[trillian]

I was pleasantly surprised to find it wasn't under-powered! There have been a lot of negative comments about the old Hirobo engines. Denis Stretton reckons the timing is critical, and needs setting up very carefully. Whoever set this one up clearly knew what he / she was doing!

8-)

--
Pete

The other thing I was going to look into is any way to eliminate the need for some of that weight in the nose for balance because it could possibly be made a bit lighter as well (but I'm not sure how much weight is practical to relocate up front to offset it)

[vrhc]

Hi Peter

How about sending me pictures and words to put in the vrhc restoration section; would be appreciated.

Regards joe

[electricsceadu]

i keep getting told how under powered the tas 24 is in the mk2 but i've not had any problems with it being under powered

and the mk2 auto's well
this model was purchased used and due to lack of time i foolishly only gave it a quick look over and checked that the bolts were tight

the elevator bell crank had the wrong bolt in it and snapped off in flight causng the heli to flip over and i had to inverted auto it
the damage was minimal flybar, main shaft, yoke, the cabin split and the boom got bent
the shafts and yoke were replaced the cabin repaired and the boom straightened and the heli stripped and re-built correctly
i can't beleave how well it flew now knowing how poorly it had been built with shims and spacers fitted in-correctly throughout the machine
its now had 5 hours flying after the rebuilt without a single problem

and a lesson well learnt

[pchristy]

Yes! I've learned a few lessons the hard way like that too!

Joe: Will do, but I've really only just started on it, and there's still a lot to learn and sort out on this model yet!

--
Pete

[vrhc]

OK Pete

When your ready.

Joe

[pchristy]

Dropped in on an old friend today who had some spares for the Bell 47.

Look what he had parked at the bottom of the garden....!!!





--
Pete

[trillian]

Dropped in on an old friend today who had some spares for the Bell 47.

Look what he had parked at the bottom of the garden....!!!





--
Pete

'Cool!

It's flybarless as well

[SimonV6]

'Cool!

It's flybarless as well

yeah.....but i bet it doesn't have a 3 way gyro

[pchristy]

Update:

Bell 47 had its first post-overhaul flights today! Its now flying much better though the tail response leaves a lot to be desired. I'm not too impressed with the new gyro I bought for it - it feels like there's no gyro there at all!

It took me a while to get the engine running smoothly. At first I thought it was a mixture problem - I could either have it 4-stroking or losing power (lean?) but never just right. Eventually I realised that it was the ignition cutting out if it over-revved! I reduced the throttle and increased the pitch a bit, and all of a sudden it was running as smooth as silk!

So all systems go for Charmouth!



--
Pete

[electricsceadu]

pete
i have two mk2's both with hirobo tail blades but the newer one has longer tail blades
the one with the shorter tail blades lacks in the tail dept in strong wind but the later one has plenty of tail power
so it may be worth trying some longer tail blades to it if they'll fit

and they both have the same gyro/tail servo

[pchristy]

Its certainly slightly lacking in tail authority, but I can live with that. It just doesn't feel locked, even though I'm running 100% gain!

On my Morley (and my Lark) I've now fitted the basic CSM 180s, which work excellently, but don't seem to like working with the Spektrum radio. The Lark has an ordinary PPM set, and works fine. The Morley has a Spektrum, and every time I switch it on, its a 50/50 chance whether in centers properly, or 45 degrees out! I assume that its trying to calibrate itself whilst the Spektrum is also initialising. (Anyone else experienced this?)

So for the Hirobo, I bought a Futaba G191. I don't need or want heading hold in a scale model, nor do I need in flight gain adjustment for this type of flying. However, even on the ground, it seems very unresponsive to getting hold of the boom and waggling it. The gain pot seems to adjust it between none and minimal! Certainly 100% gain doesn't produce anything like the response I would expect!

I've found an old JR 3000 lying around that will probably do better - a bit over the top maybe, but hey! Its sat in the junk box! But will that work with a Futaba 3152 servo (which is what I have on the tail)?

I am investigating alternative blades for both main and tail, as it only has the standard woodies on at the moment. The only ones I've found likely to fit so far are NHPs. Anyone got any other suggestions?

--
Pete

[vrhc]

I Have a few of the older Piezo type gyro's that do the same. First switch on and they don't centre correctly but switch the Rx off then on again and they do. Possible due to voltage buildup in the system not being quick enough.... not 100% certain but they certainly seem to work Ok once centred.

Joe

[lawrencelkl]

Hi Pete,

It might be coincidence that I am also working on an Old Hirobo Bell 47G. I think it is the MK I as yours as i can easily recognize the metal head.

Unfortunately, mine have the metal part holding the bearing and flybars broken at one side. I secured it with additional aluminium which bolted down to the main metal piece but i would like to have a proper head to fly with, safety!

May i ask if your friend do have a spare metal piece ( connected to flybar rods) ? if so, may i know if i can buy it from him? I have got this 2nd hand and non-runner. same to your surprise, i heard a lot about under power but it is not! lift with no problems even with serious off blade tracking!

also, may i know the length of the main and tail rotor blade u are using? i am using 800mm main wooden blades ( handmade myself ), and 130mm tail blades.

same issue, not enough tail authority. so i am cutting a pair of 145mm tail blades ( pretty much the limits before it 'touches' the tip of the main blades ).

I am hoping to test with the longer tail balde this weekend! meanwhile, oil mix is 25:1.

this vid is taken for her first ever flight in 20 plus years! not the best but enough as an accomplishment!

Cheers.

Lawrence


[ame="http://www.youtube.com/watch?v=2fUDVRB6ZHo"]YouTube- Hirobo Bell 47 G Gasser Heli Test flight 02[/ame]