Blackhorse Chipmunk 64"

[Simon Chambers]

Hello all,

My Christmas present this year was a nice juicy Blackhorse Chipmunk and now its the time that I want to start kitting it out. However I am having a couple of dilemmas!

The first is which power train to go for. The choices I've decided upon is:

1. Gas/Petrol 2-stroke engine (RCGF 15cc, NGH 17cc, etc). Pros: Virtually no mess, cheap to run and reliable. Cons: Expensive to buy and silence properly, sound is a bit too chainsaw like.
2. Electric (~1.5kw setup). Pros: No mess, quicker setup at the field (no faffing priming and starting engines - just plug in and go) and cheapest in the long run (providing packs last reasonable amount of time). Cons: No battery hatch in model (hassle charging, plus more chance of rash from replacing wing every charge time), not a great sound (for a scale-ish plane).
3. Glow 4-stroke (SC90 4s). Pros: Nice engine note (closest to scale out of all of them), cheaper engine than gas. Cons: Thirsty and expensive fuel and messy (I hate cleaning up the mess from my 2s glows).

Now this is my first model with an engine larger than a 60 size, and I've never had a 4-stroke before. So most of this is unfamiliar territory. I'm currently inclined to go the Gas engine route, as it seems the least hassle in the long run. What would everyone choose given the options?

The next problem is servos! I've whittled it down to the Hitec HS-322HD, HS-325HB or even the HS-311. What is the advantage of the ball bearing on the output shaft of the HS-325 - compared to the bush bearing of the HS-322? Is it worth the extra £2 per servo for it?

What is the advantage of karbonite gears (HS-322/HS-325) over the standard nylon of the HS-311 - would I see a benefit on the chipmunk having karbonite gears?

Any help or advice would be greatly appreciated!

Cheers,

Si.

[Tim Mackey]

Why not consider A123 cells in an electric setup - no need to remove to charge, and can be charged in 20 minutes!

[Simon Chambers]

That's not a bad idea. The next question, where is a good source of LiFe cells?

Hobby king appear to have a couple of reasonable packs: Turnigy 4500mAh 6S2P 30C LiFePo4 Pack
However not a great selection, especially compared to the amount of LiPo packs available now.

[Lee Smalley]

and if you want more than 2 or 3 flights how are you going to charge them ??

personally the gas route is one option but the engines you mention i have no experience of as to reliability, at that size of engine i am not sure you will see much benifits price wise, when you take into account the extra cost of the engine, the servos you mentions would not last very long with a petrol engine either so you would have to invest in metal gear servos, so personally i would go for a fourstroke if you run it on weston liquid gold its not that messy and if you run the exhaust properly then most should get expelled into the air, Karbonite gears are tougher than nylon and are more able to withstand the vibration of bigger engines, although my 325HBs lasted about 15 minutes in my yak whilst running my Moki 180 in before the gears disintergrated

[Tim Mackey]

Posted by Simon Chambers on 20/02/2012 16:01:20:

That's not a bad idea. The next question, where is a good source of LiFe cells?

Hobby king appear to have a couple of reasonable packs: Turnigy 4500mAh 6S2P 30C LiFePo4 Pack
However not a great selection, especially compared to the amount of LiPo packs available now.

Personally, I wouldnt touch anything but genuine A123 industries LiFe cells.

They are available from a few selected UK dealers, Puffin models, and Electricwingman to name two.

[Biggles' Elder Brother - Moderator]

I have one of these - smashing model, great to fly. Mine has an OS91FS on-board and sounds gorgous. Sometime I can just fly circuits listening to her! Sad? Probably. But hey, I don't care, I'm happy

BEB

[Turbycat]

I had one fitted with an OS61FX 2 stroke. It flew really well and with a well ducted away exhaust it never got too dirty. Personally if I had anoter one I'd go the 4 stroke route. I'm not too sure about the smaller petrols you mentioned but I have a CRRC 26cc and an Evolution GT26 petrol and I always seem to be messing about tuning the things.

Andy

[Simon Chambers]

Posted by Biggles' Elder Brother - Moderator on 20/02/2012 17:04:37:

I have one of these - smashing model, great to fly. Mine has an OS91FS on-board and sounds gorgous. Sometime I can just fly circuits listening to her! Sad? Probably. But hey, I don't care, I'm happy

BEB

Nothing wrong with that. Infact its persuading me to think down the 4-stroke glow route again!

Does synthetic oil really make virtually no mess? I'm currently running on Als Hobbies brew (no idea of its exact content) which apparently does contain mostly synthetic oil but still has some castor. I still find I have to clean off considerable oil crud off my planes at the end of the flying session - however I don't know if that's simply the castor oil in the fuel still. Is Weston Liquid Gold fully synthetic?

[Martin Harris - Moderator]

How heavy are these Black Horses - or do people like trying to put them into orbit? See this thread for lots of opinions...

Mine is that a 70FS would be OTT but very nice.

Re. your last post, it very much depends on aerodynamics.  A 1/3 scale Miles Atwood Special that I built with a 180 FS had a tiny stain around the silencer exit and I never had to clean ANY oil off the airframe. My Cub with a 160 FS plasters it all over the undercarriage and rear fuselage in copious quantities. My Airsail Chipmunk (OS 52FS) gets slightly messy under one wing.

Edited By Martin Harris on 20/02/2012 17:37:38

[Tom T]

mines got a supertigre 51 sounds nice, never flown it yet.... i thinks its a 51 anyway

Edited By Tom T on 20/02/2012 17:45:16

[Paul Marsh]

I have a RCGF 15cc and been flying that and the plane it's in for a year now. Totally reliable engine, starts easy and quite powerful. It replaced a OS BX108, and although not as powerful, enough for the Yak it's in. Cheaper to run, as the same tank only lasted 6 mins, but after a 15min flight, still half full. (bung changed). Also bought another engine, ready for another doner.

The only problem, it is quite noisy, but can be silenced.

Don't bother with the 'lectec, boring, ok for foamies, but not a scale model.

[Simon Chambers]

Here are the lumps that I looked at:

1. Glow - SC91 - £135 - Servo Shop
2. Petrol - RCGF 15cc - £165 - Als Hobbies
3. Petrol - NGH 17cc - £180 - Just Engines
4. Electric - Motor - Turnigy .60 glow equilivent - £33 - Hobby King
   - 4 Cell 5Ah pack - ~£50 - Giant Cod
   - 60A speed controller - £37 - GiantCod

So Electric is potentially about the cheapest Total Cost of Ownership - depending on the life of the flight pack.

I reckon glow would be the most given the cost of fuel (especially synthetic based)

[Simon Chambers]

Posted by Paul Marsh on 20/02/2012 17:44:36:

I have a RCGF 15cc and been flying that and the plane it's in for a year now. Totally reliable engine, starts easy and quite powerful. It replaced a OS BX108, and although not as powerful, enough for the Yak it's in. Cheaper to run, as the same tank only lasted 6 mins, but after a 15min flight, still half full. (bung changed). Also bought another engine, ready for another doner.

The only problem, it is quite noisy, but can be silenced.

Don't bother with the 'lectec, boring, ok for foamies, but not a scale model.

Have you silenced it, or using the supplied 'sound deflector'? I saw there are Pitts silencers available for them which have internal baffles, but I don't know how much difference they'll make.

Our club site has a fairly short take off area which can be quite rough, so I need a good strong engine to get me airborne in fairly short roll - hence want something more powerful than the recommended 70cu.in. 4-stroke. Also it doesn't have a strictly enforced 82dB sound limit, however we have had complaints recently, so I can imagine it'll be enforced more rigorously now.

[Paul Marsh]

I know Brian Winch discussed the said problem and solution to the RCGF 15cc, by adding baffles and cladding the loudbox in stuff, to deaden the drone and rattle.

Also, I bought a brand new RCGF of the "ethingy" site for £100 delivered. A tidy saving of £70, as it came with some props, etc.

[Alwyn Gee]

Hi

Been flying mine for about 18 months with electric setup KMS 4120/05 motor, Flighttech 60A ESC and a 4S 5000 mah Turnigy battery fitted into th fuel tank and the tank secured in its usual position with a velcro strap. The open neck of the tank provides ducted cooling for the battery. It's no great task taking the wing off to change batteries, no worse than some models where you have to take screws out of access hatches.

Flies well on this setup and will do anything the real thing can do.

Alwyn

[Trevor Crook]

Simon

A few observations from an electric convert. Your pricing above reflects my experience that using Chinese sourced electrics is cheaper than glow. I don't think you've mentioned whether this would be your first electric model, though. If so, remember to factor in the cost of a charger, wattmeter and a hefty 12V field battery.

I've converted several glow ARTFs to electric, and have always performed surgery to give easy battery access - if you've come from a traditional modelling background, you should manage ok.

If it's any help, my son has a 64" Seagull Decathlon that flies very well on a 700W setup.

I'm with you on the aversion to oil - my electrified Flair SE5A is a joy to take home compared to its OS40 FS predecessor from 20-odd years ago. Mind you, that did sound soooo good puttering past!

Good luck with whichever way you decide to go

[Biggles' Elder Brother - Moderator]

Re the question on synthetic oils. I use a synthetic oil based fuel and have done for sometime. No residue like you get with castor - no varnishing. You will get some oil on the model - how much depends on where you place and how you arrange the exhaust. I find its usually possible to find an arrangement such that the vast majority of the out-flux misses the model.

Its just a personal view obviously, but I'll except a modest about of mess in return for that lovely sound!

Regarding Martin's comments: I think we have discussed this before but I have to say that mine doesn't feel overpowered with the 91. Having said that it does give me sufficient power so that I could fly it in a most unscale-like fashion if I chose to! So a 70 would probably be OK but then you might be limited to a more scale-like flying envelop as opposed to it be an option!

BEB

BEB

[Graeme Poke]

I have this model powered with a Saito 80. More than enough power and it flies beautifully.

I have used synthetic for years and yes there is a little mess but much better than castor and I can live with it.

Magpie

[Simon Chambers]

Thanks for the comments, its been really useful to help me decide. I think its one of those things that every route has valid points and I'll have to prioritise which is the most important factor.

So I think I may go down the 4-stroke Glow route - purely for the sound aspect and that most of my fleet is electric - so its nice to have a bit of mechanical mayhem at times. After all, noise is quite important as this is supposed to be a scale aircraft. The deciding factor will probably be if I see a good value 90 for sale (a Laser would be nice) on eBay/BMFA classifieds!

In regards about the servos, which would be the most appropriate - HS-311 (nylon, cheap), HS-322 (karbonite, brass bushings on output) or HS-325 (karbonite, bearing on output)?

What servo's is everyone running in theirs?

Si.

[Martin Harris - Moderator]

Great choice whatever size/make you go for!

I don't think you'd need anything special in the servo department for this size/type of model but I'm not familiar enough with the various Hitecs to recommend any one in particular. I'd be happy enough with Futaba 3001s...

[Graeme Poke]

Hi again Simon,

This is one of my favourite models but there are two things I don't like about it.

First the rudder/tailwheel arrangement is not the best and I am still fighting with it.

And second the main undercarriage I found to be weak and constantly bent on landing. Of course, I am not the best pilot in the world so it could be just me. However, I changed to another set of main struts I had in my bin and that problem has been eliminated.

Otherwise it flys well and will do all the aerobatics that I throw at it. Hope yours goes as well.

Magpie

[Graeme Poke]

Me again Simon,

I forgot the sevo query. Age & dementia again!

I am using standard JR servos. Nothing out of the ordinary is needed.

Magpie

[Biggles' Elder Brother - Moderator]

I can't remember what servos are in mine - but they will be standard Futaba; 148's/3001's or the like. Nowt special.

BEB

[Lee Smalley]

the Hitec 485HB is an awesome servo for the cost about 12 quid and knock spots off the 322/325 hb for centering and precision, pay the extra 20 quid and enjoy !!! you will not regret it

[Solly]

Hi, I would recommend you look at the RCV 90 CD (not the SP engine). I have found these to be ultra-reliable in the air, especially when run on Prosynth 10% fuel. I have two of these and they never let me down.