Old Hirobo Bell 47

[electricsceadu]

for the main blade nhp 800's or bbt evolution 795's work well on the mk 2

and they both have a 401 gyro with the 9254 servo running in rate mode

i have no idea with the jr3000 and the 3152
but if it works ok on the bench i can't see it not being ok in the air


and on my morley's
a futaba 154 on the 4 stroke
and a 401 on the electric

[lawrencelkl]

Works continue on the bell 47G

hey guys,

how is it going?

I have recently started to work again on my MK1 (i believe) hirobo bell 47G.

I have the nhp 800 carbon main blades fitted and it is doing much better than my handmade woodies.

the gyro / tail servo used is now GY401 and 9254.

one thing that I realised is that this gasser demand much more fro mthe receiver power supply. I had NiMH 3700 4.8V and it wont last even 2 short flights. the first flight seems ok and then the second the tai lstart to loose command. i have did some research and ordered LiFePO4 (A123) 2 cell 6.6V pack. I ordered two to hope having redundancy in power supply. may i know what receiver pack you guys use in this gasser?

has anyone used A123 for this gasser? and does it mean i can then plug in 2 pack in any two spare receiver port? i understand that 9254 is limited to 4.8v so i have a 5v regulator between gyro and 9254 tail servo.

did not have any luck trying to get a spare metal flybar holder(Gimbal?) so i have adone a metal repair work, which i think should be good for now.

vibration is still a big issue, may i know how you guys deal with this? how to reduce vibration etc?

many thanks.

Best Reagards,
Lawrence

[electricsceadu]

on the rx packs i use two 5000mah sub c type nimh packs with twin switchs
the older one has had the tail boom lower mount beefed up which i assume will be due to the std lower mount tubes breaking with vibes
the new one has the cabin on rubber mounts (std by hirobo) which i assume is to help the rx and gyro from vibes)

note both mine are the mk2 versions

with the head you may end up with an eagle or freya head so it can be used, the other option is the mk2 head




Pete how is the rebuild on your Bell 47 going?
It was sad news to hear that it had a bump at charmouth

[trillian]

One thing you might consider for redundant RX power is using two regulators each with it's own 2 cell Lipo.
This would be considerably lighter than big NiMh packs and has the advantage of not taking ages to charge.

I have done this with two 5 volt Duralites and 2200mah 2s LiPos.

Another option is something like the Powerbox with a separate battery for the servos and another for the
RX.

[electricsceadu]

the two nimh packs act as the counter balance to the boom
the later one had a ton of lead stuck inside the cabin with a small rx pack ,out came the lead and in went 2 large nimh packs, if i put weight into a scale heli it will have a purpose, battery/scale detailing/pilot etc, i never wish to add dead weight
and the problem with lipo's is you need to remove them from the heli to charge them
it's not a good option when the battery is buried under the cabin floor

[trillian]

the two nimh packs act as the counter balance to the boom
the later one had a ton of lead stuck inside the cabin with a small rx pack ,out came the lead and in went 2 large nimh packs, if i put weight into a scale heli it will have a purpose, battery/scale detailing/pilot etc, i never wish to add dead weight
and the problem with lipo's is you need to remove them from the heli to charge them
it's not a good option when the battery is buried under the cabin floor

Hmmmm, I forgot about the tail heaviness issue with that heli.

[pchristy]

I've not had any problems with power issues on my 47, and I'm just using simple 4-cell Eneloop packs. Since these are a lot smaller and lighter than the old JR 1900s I used to run (and sadly no longer available), I've had to add a bit of lead up front to get the CofG right.

The rebuild is going slowly at the moment. I've finally got all the bits I need - the last part was the casting that connects the boom to the tail gearbox tube. Dave Nieman came up trumps for that one a couple of weeks back. However, in the mean time, I've been slightly waylaid by buying another 40 year old car, which has been a bit demanding of my time for the last couple of weeks!

Hope to start reconstruction of the 47 soon though! I'm also looking for a replacement ignition system for it, as Dave N. tells me the old Hirobo one is probably responsible for the misfire I was chasing when the link broke! The engine is NOT what I would call smooth! Vibration is an issue - probably the ultimate cause of the link failure - but there's not a lot you can do about it - gassers are like that!

Along the line I have picked up a chassis that has been modified to take one of the big Super-Tigre motors (25 or 30cc), but that seems a bit of an extreme measure! Fuel consumption might be an issue, I suspect, with the standard tanks......!

[electricsceadu]

would the mk2 tas 24 or a zenoah not fit into the chassis?
i'm lucky as mine are the mk2's that don't have the ignition truble of the mk1's

[pchristy]

[QUOTE=electricsceadu;665665]would the mk2 tas 24 or a zenoah not fit into the chassis?
i'm lucky as mine are the mk2's that don't have the ignition truble of the mk1's[/QUOTE

Not sure - tha TAS is a completely different engine, and the Mk2's mount the engine in a completely different manner. It might fit into the old mounts, but I would need to try one to be sure. Its a lot of money for something that might not work!

[lawrencelkl]

Hi Pete,

may i know what is the capacity of the eneloop that you are using?

I am also using the old hirobo ignition box and thinking of upgrading as well. please let me know if you have found a good one that works well with the MK1.
Mine is using the old hirobo 20cc engine rather than the newer TAS.

you are in touch with Dave? i saw a pdf showing him flying the bell 47 G in military scheme.

Also, may i know if your bell is the one with helical gear as well?

thanks.

Lawrence

[lawrencelkl]

No wonder my 3700mAh give such a short time , or it maybe that it is just not a good pack anymore.

does anyone know where can i get a MK 2 head or eagle/freya head as sugested? thanks,
Lawrence

on the rx packs i use two 5000mah sub c type nimh packs with twin switchs
the older one has had the tail boom lower mount beefed up which i assume will be due to the std lower mount tubes breaking with vibes
the new one has the cabin on rubber mounts (std by hirobo) which i assume is to help the rx and gyro from vibes)

note both mine are the mk2 versions

with the head you may end up with an eagle or freya head so it can be used, the other option is the mk2 head




Pete how is the rebuild on your Bell 47 going?
It was sad news to hear that it had a bump at charmouth

[pchristy]

The Eneloops are just 2000mAH, but I'm only using fairly basic servos (Futaba S3152s) - they seem to be well up to the job!

I found a company doing a micro-processor controlled ignition system for around £50:

Ignition Systems

Since this calculates the advance from the rpm, it would need the mechanical advance locking, and it might be tricky installing the new sensor, but it looks promising!

I've also been meaning to chat to Dave Wilshere, as I would guess he might have something suitable.

[lawrencelkl]

Hi Pete,

thanks for the info. do you also use s3152 for the tail? which gyro have you got there?

please keep me posted if you found any good replacement for the ignition.

cheers!

Lawrence

[electricsceadu]

my mk2's have futaba 401 gyros with the 9254 tail servos

[pchristy]

The tail servo is also a 3152, and I'm just using a basic Futaba gyro - I forget which one, but its just a basic rate gyro - no need for anything else!

I've used the little CSM rate gyros with some success, but they seem to have an issue with JR/Spektrum receivers. They appear to try and calibrate before the receiver has locked on to the transmitter, with the result that its a 50/50 chance whether it centres properly when the receiver boots up! It works fine on my Lark (459 MHz ppm), but is a complete pain on my Morley Bell 47 (Spektrum Rx).

Its going to be at least a couple of months before the Bell is airworthy again. I'm going to have to remake every pushrod out of bicycle spokes for security, and I have to strip the paint off the replacement boom before I can re-spray it! Plus sorting out the ignition, and its going to take a while.....!