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Ron’s HeliProz South . Century Helicopter . MTA Hobbies

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Gasser Model RC Helicopters > Spectra Kit arrived
 
 
pgkevet
Senior Heliman
Location: surrey UK

Quote 
been married for 14 year

double that, add a bit and your bowel becomes resigned

pgk
06-09-2008 09:24 PM
 
 
Fixit
Key Veteran
Location: UK

Quote 
double that, add a bit and your bowel becomes resigned

I know the feeling well
06-09-2008 11:53 PM
HOMEPAGE  
 
 
pgkevet
Senior Heliman
Location: surrey UK

build thread - head finished

So what to say? Well the head sure looks pretty. This is the Tempest. I'm not sure how many folk will really use the potential adjustment. I just stuck everything in the middle holes.

Why build manuals can't tell you how to really do stuff I don't know. Here the advice is to assemble all the bearings and spacers onto the feathering shaft and then slip the grips over that and screw them down onto their split ring lug. I did try but it was never going to work short of pounding seven bells out of the blade grips. And no-one in their right mind is going to stand near 710 blades on a gasser with damaged grips.

The only way to do this is to take the individual parts and slide them inside the blade grip and persuade them down with a correct sized socket wrench head with the blade grip sitting on a piece of timber within the grip. You could use a vice or clamp to squeeze them down but I used a rubber mallet and tapped (yes just tapped) the items in individually. Make sure you keep those screw holes straight all the way down.

Comparison to the Preddie?

The preddie head is a way easier build. If it came with the upgrade parts instead of stock parts it'd be personal opinion which was prettier. Stcck the Spectra wins but it wasn't a cakewalk. The Preddie feathering shaft looks horrid but feels smooth and you can't see it when done. The spectra shaft oozes neat machining. Preddie dampers look like someone thought about it instead of just buying some cheap o-rings and rebagging them.

The Preddie build manual is poor beacuse it has too many variants in one manual - layout is good, the Spectra needs review and having pics spearate to text is a nuisance.

pgk
06-09-2008 11:56 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Build thread - Left Frame

OK so these parts look the business. The carbon frame is pre-studded in several places and that gives it a promise of quality.

There are a number of bits to be attached to this and provided in a well labelled bag. Tip them out and sort them into piles by size.

Once again machined parts have a satin finish - it's just my opinion but the Chinese would have polished them and had you drooling.

According to the build picture part #106-41 is the front canopy mount. The pic shows this to be a length of threaded hex bar. MinAirs Parts list states this is black and 35mm long. The back canopy mount provided is silver and hexagonal. By elimination the one part 35mm long is silver and nothing hexagonal about it - a substitution or kit change? Little losses of detail like that lose points. If you lost one and re-ordered would they match?

Once finally identified then assembly will be a simple plod. there's nothing here that could be an issue. Points gained.

(yes you need either a handy laptop or a massive printout to keep up with the combination of written instructions, diagrams and parts list. The good news is that at least it is documented if clumsy)

http://www.miniatureaircraftusa.com...y.asp?kit=';1025'&path=kits
http://www.miniatureaircraftusa.com...d%20Rev%204.pdf
http://www.miniatureaircraftusa.com...d%20Rev%205.pdf

Predator comparison

I'm trying to be fair in all this..not knocking either machine..but I may be one of the few to build both.

The Preddy carbon parts are just as well machined but straight comparisons are hard. An entirely different design style. Again Ally parts are satin except for the frame spacers which feel beautiful, make the frame very, very strong but the need for alignment slots between upper and lower frame parts allows for possible wear. It was clumsy to mate up and finish off but it's looks are really cool when done.

pgk
06-10-2008 06:48 AM
 
 
Fixit
Key Veteran
Location: UK

The Spectra is a dream machine and the Predator is the runner up

I think you will find plenty have built both machines but just haven’t done a review as such.
I hated working on the Predator with all the frame spacers its so fiddly and without moding the frames it's a strip down to get the engine out, the Spectra was a dream to work on, if you run all the wires up top when you build it the frames part in 2 minuets and the engines out in 10 minuets.
06-10-2008 11:21 AM
HOMEPAGE  
 
 
pgkevet
Senior Heliman
Location: surrey UK

The issue with the preddy spacers was mostly where they are stacked.. trying to keep thm together while threading the bolt through. My solution was to stack them onto the bolt and use a drop of ca to bond them aligned.. then putting them in was easy - just a chore. My day job means I use instruments to assemble most stuff anyway.

I agree re the engine removal and also agree re the design requirement to align the top and bottom frames via the clutch-bell relationship.

Considering my recent dive into the ground has crimped the engine baseplate I can't complain about the stength of the stacked carbon frames which are unscathed.

If there are folk with both then I'm happy not to use space with the build comparison..

pgk
06-10-2008 11:48 AM
 
 
turbogti
Veteran
Location: St. Andrew, Jamaica

pgkevet, this thread is a much anticipated comparison as can be seen by a search of "Predator vs. Spectra G", these are questions that are asked by potential purchasers of gas helis.

I'm myself am watching this thread as i am curious as to the comparison in build, flying & maintenance.

The stacked frames are by no doubt very strong, i have come across a few onwers how have dumped their predators without damage to the frame.

I doubt that you will be doing a comparison willingly on this with the spectra.

Anyway Keep it up pgkevet and be as objective as possible.

****Predator Gasser SE - She's Ready to rumble ***
06-10-2008 02:24 PM
HOMEPAGE  
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Absolutely keep the review coming!

We don't care whether its good or bad, just want your honest opinion as a guy who knows nothing about the kit just following the build directions.

Its good feedback for the manufacturers if nothing else to improve stuff.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-10-2008 02:54 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Quote 
just want your honest opinion as a guy who knows nothing

It looked good to cut the quote at this point

Ok I'll keep at it.

Build thread Left Frame Bag 2 end

Have finished the left frame (Bag 2) assembly - as stated earlier just a plod after identifying all parts. Only last comment is that I actually thought the carbon felt thinner than the Preddie but meauring it they are both 2mm - odd. Also note that no washers are used under the cap bolts on Spectra. This is my fourth carbon heli build and the first time no washers. Hardly an issue but one could sprinkle lots of bling here for a few grammes weight.

It was also nice to get the main shaft out just to line up the main bearings. Nice and shiney as they should be - no gruesome Preddie patina.

I did swap the Preddie washers for coloured ones when I built that - we're all suckers for shiny stuff - a bit girlie?

pgk
06-10-2008 04:23 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Canopy studs

By the way, yes those studs are made from hex stock. The thicker ones are on the front, the thinner ones are for the rear mounts. Remember that depending on how you place the engine there are two different hole choices for those. If you mount the engine cylinder to the rear, then you need to put the studs to the rear to match, This is how I have mine -- if I remember right the instructions default to putting them in the rear with a rear facing engine cylinder in mind.

Note: The mainshaft usually comes coated with a "sticky" substance to prevent rust during storage in my opinion. I clean that off with a solvent as it will allow for a smoother motion of the parts that ride on it. Over time (especially like me if you don't crash often) the mainshaft will surface rust some due to humidity or whatnot, but its not an issue in operation.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-10-2008 04:55 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Quote 
By the way, yes those studs are made from hex stock. The thicker ones are on the front, the thinner ones are for the rear mounts.

Not in this kit!.. front one is hex, back one is more waisted tube shape.. just would have been nice if plans updated!

Quote 
Note: The mainshaft usually comes coated with a "sticky" substance to prevent rust during storage in my opinion. I clean that off with a solvent as it will allow for a smoother motion of the parts that ride on it.

Supplied in a nylon mesh tube. No obvious coating but I will check when i get back from work

Quote 
Over time (especially like me if you don't crash often) the mainshaft will surface rust some due to humidity or what not, but its not an issue in operation

I doubt that's going to be an issue for me

I don't have any old parts on any of my helis <sigh>
They all look brand new!!

pgk
06-10-2008 05:39 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Not a big deal anyways

Its just a spacer to support the canopy and manufacturers replace parts here and there something depending on the lot of parts that they buy in bulk. The Spectra-g kit didn't used to come with that flybar "cage" so to speak and now they have upgraded it (mine didn't come with that, I bought it as an upgrade later) as to what you found in your kit but apparently the manual didn't match. Its understandable probably because they made many CD's for the kits and they want to use them, but nevertheless I'll give that feedback back to them.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-10-2008 06:07 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Quote 
Not a big deal anyways

I agree it's not any sort of major issue but when unfamiliar with the parts it took some little while to plod through MinAirs part numbering to be sure I'd identified the correct bits.

The drawings provided look cluttered at a prinable size and even if you scale them up on screen the lines aren't that clear. It may be a small point but compare that to your trex manual and see how well presented drawings can be. Preddie images are in small sections and also a little confusing with differing models and options. Again good line drawings are my preference. Age, spectacles and artificial light when building don't help.

I've finished the first 20 pages of text and 20 pages of diagrams.. another print run required..

Build Thread bag 3 partial

Tal drive shaft parts well presented, simple to rough set. The collar provided looks like the collar on my 450 mainshaft except that has two set screw holes. I have had one of those strip ona couple of collars. While it may never ahve been an issue here I would have used two holes for that or avoided ally collars.

The Preddie tail sits in differently - easier to pull it all out but more of a fiddle to see and adjust gear mesh.

Main gear and sprag bearing. Beautifully machined parts on the Spectra. I can't quite see why it takes 8 screws to hold the tail drive auto gear. You can't complain at keeping the nylon flat but my 600's main drive gear only has 5 or 6 screws. Assembling and oiling it is messy fun if you drop stuff in your lap.

Preddie came with this pre-assembled and screws too solid on testing to justify taking apart. What is visible on the \preddie is also substantial and well engineered.

Installing the mainshaft on either is straightforwards enough but on Preddie there are differences by model to identify.

I'd put Specky ahead here because the bits look cool and because the gear mesh will set easier. I'll find out later in the manual how easy it is to pull the tail. On Preddie you could easily undo a few screws and take tail off for travelling without it being too tiresome.

For the record I ended up with both shims in the gear and free rotation on Specky.

Are these gears machined by each company or bought in?

Note: On Specky the thrust bearings state 'japan' so not cheapo chinese bearings there. On Preddie they have the manners to label them in and out so if you have any difficulty deciding which has the smaller ID it tells you.

pgk
06-10-2008 08:26 PM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Build Thread right frame mated

Absolutely no suprises or issues her..as a good kit should be.

Isn't it thin! - looks like you could shove it through the park railings..No wonder Preddie use the words monster - but he's a solid beast!

It's late here - whiskey beckons.

pgk
06-10-2008 11:25 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Allright!

Step 3 passed inspection! It starts looking like a really nice piece of equipment when you get the main gear inserted with the main shaft onto the frames -- now you can feel/see some quality!

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-11-2008 02:05 AM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

opps, posted in the wrong thread!

Quote 
stock gear ratio is 6.28, 3200 RPM = 20,000 rpm on the engine.

...yep...
06-11-2008 02:21 AM
 
 
nitro fun
Senior Heliman
Location: wilmington ca

how many teeth are the pinion and main gear? for the gaser?
06-11-2008 05:38 AM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Build thread A) bell swash and rudder bell cranks.

Oh, dear! These are just horrid. Flimsy looking, needs lots of care to get the balls screwed in straight and the swash cranks spindle and locking collar just look lke you could catch them getting it out of the car and ruin your whole day. I know what I going to be writing about the next stage and these parts here have no place on birdie..they scream upgrade. The rudder crank is better bu far but I dont like the way you're expected to shove a bolt with locktight on it's threads through a bearing centre - and yes, the manual does at least warn folk.

These cranks are plastic cupholders in a Ferrari. At least on Preddie they look solid - even if they are the same basic approach the actual attachment is way stronger.

OK so we've got two different birds. If you were in the woods and attacked by bears you could club most of them to death with a Preddie and still go flying. With Speckie you'ld want time to take out the Zenoah, wire it to a branch, hide the heli and just wade in with your stick-motor.

Build thread B) Clutch/bell/pinion

Wow!! Isn't that a piece of work? I had to go rinse out my Y-fronts when i saw that! I want another one of those polished up more and under glass as an executive Objet d'Art on my desk. You could drool over that all day. Everyone..rush off and go see one - take some tissue!!

As for fitting it..Wha - a dream.

Criticism? Well only that with the number of doubler plates ya sorta wonder why they didn't bite the proverbial bullet and use 3mm carbon all round - bin those naff cranks - Oh and that absolutely appalling gyro ledge and stick 50 quid on the bill.

The front fuel tank ledge attachment is awkward..my trusty heamostats got in to the nuts - that or you need a very fine tube spanner or similar. That could have been avoided by threading the anchorage or using those auto spring nuts.

But hey.. that clutch and bell put Preddie way down the field.

<pause while i go clean up>

The other clever point was getting this far in the build before playing Zenoah Engines. That was the start and the frustration on Preddie..everything else Preddie was easy after that - just needed counselling...

And next the Zenoah..

pgk
06-11-2008 09:50 AM
 
 
pgkevet
Senior Heliman
Location: surrey UK

Build Thread - Engine

Doesn't matter whtehr it's Preddie or Speckie but it's part fo the build thread and 'fun' to sort the Zenoah.

There's some huge Sumo Wrestler working part time in the zenoah factory making engines just for me. He uses a length of scaffold pole to make his torque wrench longer and really get those bolts tight. I thought I'd beat him this time..clamped engine in a vice and realy leent on that driver to get max downforce on the baseplate bolts before turning. I got three out first go and broke the zenoah driver (again) on the fourth..used my own and out came fourth cross-head - easy!
The guy had been teasing - I really had to use my biggest socket set on that plug. Finally got it and after cleaning blood off the engine we were ready to carry on.

Here MinAir lose a few points Written instructions saying to remove the starter lug and place an M6 nut underneath it. A picture showing that nut and a washer saying not to use the nut and an unlabelled ring washer sellotaped to a corner of a packet picture insert - not as obvious as it should be under sl opaque tape and a light ring washer you don't notice straight off. An arrow and a scrawled part number could have saved the nuisance - as well as editing the written manual. Buy a rubber stamp Minair!

The preddie fan is a work of art.. shiney, smooth and looks the biz. Speckies fan was loose in a bag of parts and had lost any shine and had that dull old aluminium look about it. It's undoubtedly a better basic design with damper inserts for the clutch mesh - that avoids clutch dialing but it looks cheaper than the kit deserves. Polish i and wrap it separately.

I'm now an expert at fan dialing. Start by dialing the engine taper.gives you confidence - less than a tenth of a thou. Place fan on with bolt and washer loose. Twist fan to seat it and dial the top surface outer edge. Keep twisting the fan to see if it seats better and redial.. sorta go around the clockface untilits as good as can be.. then start to tighten the bolt. That got me to within about 3 or 4 thou without any stress. Find the high point and gently - I mean gently - tap it with a rubber hammer and recheck. It moves the high point a bit and reduces it.. took maybe 5 or 6 little taps to be down to 1/2 a thou or better. Lock the piston and torque down the bolt.. check it's the same. Then dial the side of the fan hub.. i was in the target zone just under 2 thou but had to have a play.. so slackened the bolt and tried again. This time I had the top to almost perfect and the side under 1 thou - good enough for me.

Then with that bolt torqued down as much as I could with an allen key and my 220 lbs and 6 foot 8" of leverage i tapped the fan again ..gently (we're talking cracking peanuts) and that moved it out by over a thou. Try it.. that makes the whole excercise a bit lame. I put it right and retightened and left it.

Dampers fitted easy no powder or spit needed.

Conclusion

Since it's way easier to dial justa fan than dial a fan and clutch then Speckie wins. I can;t wait to test my newfound dialing powess on Preddie during his rebuild. Preddie wins on fan looks, loses on the clutch and bell system big big time.

Am I correct that it's now considered unnecessary to fit the spark wire screen? We'll be on 2.4Ghz..

pgk
06-11-2008 02:14 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Tips

Make sure you removed the engine dogbone on the bottom, placed the washer provided taped to the paper on the crankshaft, and put the dogbone back. This lowers the dogbone some for the starter to be able to reach through the lower frame.

There is no need to fiddle with the braided shield for the engine, omit that step, I fly mine without it with 72Mhz PCM. I think maybe it helps more with FM radios. With 2.4 its most likely not needed as well.

Don't bother using the one way valve or the t's for the plumbing either. Check my gallery for the setup. Fuel with return line, drain with carb line at the end of the day. In fact, the stock tank is too small, do it right with the Dubro 16oz tank you'll be much happier with the flight times. I think Minair sized the tank so the gasser will fly the same amount of time as a nitro machine, and in essence keep it lighter but most gasser pilots like the extra flight times.

NOTE: When you assemble the engine on the lower plate, there is a starter plate with key holes that goes in-between the engine and the start plate to allow the starter to enguage. It can go on correctly or backwards one way its right the other the starter won't fit. Most people make this mistake here in assembly (50/50 shot). To be sure its right, look at the bottom of the plate and you should see the keyhole slots through the bottom plate holes.

Keep it coming!

P.S. My bellcranks are the original platic ones, they have held up to all my flying in close to 3 years time so they are more than adequate! But for people who must have bling, you can get them in nicely machined aluminum if you prefer.

Oh and I know its too late now, but the way to remove the bolts on the back of the Zenoah engine is to a) use the t-wrench supplied as it fits very nicely on the phillips bolts and b) MOST importantly use a heat gun on the bolts and wait until they get hot and they will turn out with plenty of ease. Stripping of the heads comes when people don't heat them and try to horse them out.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-11-2008 03:03 PM
 
 
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Model Rectifier Corp . PowerHelis . JR-Spektrum

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Gasser Model RC Helicopters > Spectra Kit arrived
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