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CarbonXtreme . Midland Helicopters . HeliProz

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Gasser Model RC Helicopters > Spectra Vs. Predator - Another Perspective
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

My Posts This: Topic  Forum

Like you said, I've had both, so I'd say I can compare the 2. They are both capable of the exact same things. You can change the gear ratios just as easily on either, and MA can supply you with longer booms to give you the stretched config like a Condor. I fail to see where one is more flexible than the other, your posts make it obvious that you have never had both, you certainly didn't need to tell anyone.

I can tell you this, the Spectra flies better, and requires far less tinkering than the Predator does. I've got over 6 hours on the Spectra so far, and haven't had to do a thing to it so far, I haven't had to do so much as turn a screw driver on it. Hell, I haven't even taken the canopy off in over a gallon. I certainly can't say that about the Predator. Great heli, but it certainly wasn't a low maintenance machine. Things shifted, required adjustment due to wear, and just required constant maintenance. All at a higher price and greater complexity than the Spectra.

And yes, you are bashing, same as in any other thread where the Predator and Spectra question comes up. You just did it in a passive aggressive way in this thread. Come to think of it, the way you do it, you may be my mother in law, I'm going to have to search for a heli the next time I go to her house.

Nick Crego
08-03-2008 Over year old.
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Excalibur
Key Veteran
Location: Destination: Earth

My Posts This: Topic  Forum
Quote 
Come to think of it, the way you do it, you may be my mother in law, I'm going to have to search for a heli the next time I go to her house.

Now that cracked my ass up Eury!

I looked at the frame doublers that mount the clutch assembly and decided it wouldn't be that big of a deal to slot out the six holes (per side) to fix the problem. I simply locked the two frame pieces together with two nuts/bolts on the ends and went at it. I used one of those tough 1/8" carbide cutters on my drill press to punch a new hole next to the original, then filed down the point between them. I was then able to easily finish the assembly and tighten down the clutch assembly. The main frames are now officially finished, but still require the addition of the servos, motor plate, etc. Hope to see my engine from Toxic Al early next week.

When I sat back tonight and just looked at the way the frames, transmission and clutch fit together, I realized it was no more complex than the Predator assembly. In fact, it has an air of simplicity to it. The stacked frames on the Predator are kinda cool, but I firmly believe that it actually leads to more problems in the long run. I say this for two main reasons: The tail drive and the clutch. They both are contained within the frames on the Spectra, whereas on the Predator the tail drive pinion was part of the tail boom assembly, and the clutch was split in half, with the shoes mounted to the engine and the bell mounted up in the frames. Both of these areas required alot of mechanical tweaking to get them adjusted and working properly. Inevitably this would lead to premature wear on the crown gear, and clutch alignment problems that continued to plague performance thereafter.

Yes, perhaps the newer Predators are better mechanically, but the fact that Century added a frame stiffener around the engine just added to the cost and complexity. The Spectra is simply cleaner and less complicated.

Next week: Engine install and assembly.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
08-03-2008 Over year old.
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Excalibur
Key Veteran
Location: Destination: Earth

My Posts This: Topic  Forum		Got my newly moded 231PUH from Al at Toxic Racing, and was finally able to get down to the dungeon for more assembly fun.

Following the engine-prep and assembly was pretty straight forward. To use the stock pull start, you need to remove the starter engagement key on the bottom of the engine, then insert a thick spacer underneath it and reassemble. This has been covered in detail before, so I won't go over it here. Just remember to look for a folded piece of paper in the motor assembly bag that has this spacer taped to it. Otherwise, you can miss it and end up putting the big thick threaded nut on instead (if you're strictly reading the instructions and not paying attention to the assembly drawings).

Everything goes pretty smooth from there. It is suggested in the manual that the fan be balanced before installing on the engine. This was fairly easily accomplished with a high point balancer. Once the heavy side is identified, simply flipping the fan over and using a 3/16" or 1/4" drill bit to remove a little bit of metal takes care of it nicely. Just remember to do a little bit at a time! You can always take off a little more, but you can't put it back. Once this is complete, the fan is secured in place much like the Predator with a single bolt through the center. The difference is, you don't need to check run-out on it. Simply spin it in place and gently tighten it down. I'm not quite sure that mine has seated properly, and I may have to redo it. This shouldn't be too big of a deal however, since everything comes apart quite easily.

[B][I]EDIT: I was wrong about not having to check the runout on the fan when bolting it to the engine. This came about in a conversation I had with Minair right after I wrote this post. To Clarify: You MUST still dial indicate the fan during assembly, looking for 0.0015" of runout or less. With a little trying, I got mine down around 0.001"[I][B]

Assembling the engine to the mounting plate is straight forward and goes smoothly. The tricky point is to study the assembly drawings really carefully to verify that you are placing the two smaller motor mounting frames under the engine in the proper orientation. This will be critical for proper operation of the removable pull start assembly completed in the next step. If either one of the small frames is flipped up-side-down, it will not work correctly. If assembled properly the first time, this feature works very well.

I was amazed at how easy the upper-frames assembly attached to the engine mounting plate and how little tweaking there was. The only thing that I'm trying to get used to is how tall the entire assembly is. It looks like a wall of carbon fiber about a foot high. I don't know how it compares to the height of the Predator frames, but I don't think it makes much difference to performance. The skids are secured to the landing gear frames with four set screws (one on each leg), making for a very tight landing gear assembly. This was not even addressed on the Predator kit, leaving you to either glue the skids in place or come up with your own attach method.

Here again I must give points to the Spectra for the ease of mating the main frame assembly to the motor assembly. It's as easy as pushing the two together and putting in the screws to secure everything. I think I do need to give a point to the Predator for not being so tall, and for having a dedicated mounting tray for radio components, however.

All-in-all, a productive weekend. Next, I need to mount the tank, tail boom assembly, and start the radio installation. More to come. . .

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
08-11-2008 Over year old.
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Excalibur
Key Veteran
Location: Destination: Earth

My Posts This: Topic  Forum		Life has kept me away from much building on the Spectra, but I have moved forward the past week or so.

Before I get into the details of radio mounting, do yourself a favor and LEAVE THE TAIL BOOM OFF! It is so much easier to spin the completed heli frames around on the workbench in front of you during this process. In fact, I have found that the last thing to logically be attached on any heli is the tail boom. Try it - it will make life easier.

After mating the engine tray to the main frames, I moved on to radio installation and pushrod setup. This is all pretty straightforward with bolting the servos in place with machine screws into PEM nuts on the frames. This is a nice touch and works quite nicely, with the addition of a little bit of blue locktite. All servos mounted quickly and easily.

Pushrod assembly is easy as well, with little trouble. Take time to set up the geometry correctly on all servos (90 degree angles everywhere) to lessen the tweaking later on in the setup process. All ball links feel very tight right now, and I'm not sure how much it will load the servos until they loosen up. I think I am going to leave them the way they are, because I adjusted the fit on the Predator links to be less-tight, and within a short period of time they were too loose, so I don't want to repeat that mistake. I really did like the push-pull control rods on the Predator, but will have to deal without them on the Spectra. I haven't heard of too many people having trouble with them.

At this point I went ahead and tried to attach the canopy so I could get an idea of how much room would be available for the larger 16 oz Dubro tank I was going to install. What a MESS! I took the fiberglass canopy out of the box, un-bagged it to look at it, and discovered it was a twisted, deformed, abomination. To make matters worse, there were cracks forming along some of the deformed edges with chunks of gel-coat breaking away in several locations. This was just from being shipped in the box! Anyway, a call to Minair (again) confirmed that they had a bad shipment of canopies some time ago, and that the company that made them did not let them cure properly before packing them. Customer service at Minair said they were aware of it and have new ones coming in about three weeks (mid Sept.), and would send out a new one to me if I gave them my name and address.

IN THE MEANTIME, I cut out the sections recommended to fit around the front ladder and carburetor, then drilled the four holes in the canopy and installed the rubber grommets as indicated. When I tried to fit the canopy to the frame, I had to do some pulling and stretching to get the canopy retaining screws in, but I finally did get them all in. Don't think that the four screws will straighten out the canopy and make it fit just fine. That WON'T happen. Instead, I took my heat gun and carefully started heating the canopy while it was still attached to the frame. By pushing, pulling, and gently bending certain areas of the canopy, I was able to get it reasonably shaped. I also had to cut a couple of 2" carbon rods and glue them along the top inside edges of the canopy just behind the swashplate to straighten them out where the cracks were occurring. Finally, after about two hours of work, I had the canopy fitting reasonably well, but I sure as hell ain't gonna paint it since it's a temporary fit 'til the new one gets here.

Points awarded to the Spectra-G for the easy servo mounting method and pushrod setup.

MAJOR points awarded to the Predator for a comparatively BEAUTIFUL canopy that I never appreciated until I saw the Spectra's canopy. Century's association with Funkey fuselages apparently pays big dividends for them in this area.

Next: Mounting/plumbing large fuel tank, and routing/dressing radio wires.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
08-28-2008 Over year old.
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pgkevet
Key Veteran
Location: surrey UK

My Posts This: Topic  Forum		My canopy looked good out of the box.. and I do appreciate that it was my error (again) in getting the canopy supports mixed up.. but the extra stress caused it to crack along it's seams.

Again it may have been part of this poorer batch but the solution was to add glass fibre inside along those seams to reinforce them,.. and that may well be worth doing to your new one as a precaution when it arrives.

Otherwise it's sounds like your getting on well. Work quick.. winter is coming

pgk
08-28-2008 Over year old.
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AceBird
Elite Veteran
Location: Utica, NY USA

My Posts This: Topic  Forum
Quote 
I adjusted the fit on the Predator links to be less-tight, and within a short period of time they were too loose, so I don't want to repeat that mistake.

Early on when I was a new member on RR I suggested this and got a beating. IMO the commercial reamers / sanders are bad. I used to just spin a ball in the link prior to mounting. I now have my own reamer which is nothing more than a new ball with a biased slice in it from a Dremel wheel. It doesn’t take much spinning to size the link and it won’t cut oversize.

Quote 
I really did like the push-pull control rods on the Predator, but will have to deal without them on the Spectra. I haven't heard of too many people having trouble with them.

Now that is interesting! I had that discussion too. The Spectra is more agile yet it doesn’t have push-pull links. Truly amazing, Not. Push pull links are all hocus pocus anyway.

Quote 
Points awarded to the Spectra-G for the easy servo mounting method and pushrod setup.

I’ll give you the servo mounting method but the pushrod setup… You found that difficult? I hate sheet metal screws in plastic so I abandoned the plastic t-nuts supplied with the Predator and made my own t-nuts out of aluminum. Tap is #3-48 and I use stainless screws. The problem with nuts bonded into the frame is that not all servos have the exact same center distance. So to me that is a limitation. A t-nut can be made to what ever your servo is.

Ace
What could be more fun?
08-28-2008 Over year old.
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victorb
Heliman
Location: Newark, DE, USA

My Posts This: Topic  Forum		231 PUH Engine Fan Runout

Quote 
To Clarify: You MUST still dial indicate the fan during assembly, looking for 0.0015" of runout or less.

I am presently in the re-do mode of the build, (after the first test flights showed boom supports buzzing as well as the servo set screws coming out)trying to properly perform the runout on the fan. I've looked in the achvives and can't find a procedure for this task.

Is there a procedure that you the more experienced feel comfortable passing on to a less experienced gasser builder?

I'll say this the fan balance was a piece of cake and didn't require any adjustment using a drill.

Thanks for the great reads, you have helped me muddle through many questionable tasks.

OoH, One other question: What is the concences about using red locktite in this build?

Victorb

I Have a Love Hate relationship with this hobby, Love to Build, but Hate to Crash..
08-28-2008 Over year old.
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pgkevet
Key Veteran
Location: surrey UK

My Posts This: Topic  Forum
Quote 
I’ll give you the servo mounting method but the pushrod setup… You found that difficult? I hate sheet metal screws in plastic so I abandoned the plastic t-nuts supplied with the Predator and made my own t-nuts out of aluminum. Tap is #3-48 and I use stainless screws. The problem with nuts bonded into the frame is that not all servos have the exact same center distance. So to me that is a limitation. A t-nut can be made to what ever your servo is.

A well designed heli will have enough access that you can get an ordinary nut & bolt through the servo if you wish. The helis I've built have all had some limitation on servo types by size.. but here 'standard' servos gives you a big choice. If the servo slot isn't the right size then I don't care how well you bolt stuff in it's gonna skew on it's rubbers. As you know I was critical during my build but these peg nuts do work and are easy .. and if they slip then a dab of glue solves it. Think of them as flanged nuts with a knurl to stop slippage during tightening.

I'm not sure I see the benefit of making own nuts systems when you can get nuts out of a packet. I tap enough threads in my day job without bothering at home.

pgk
08-28-2008 Over year old.
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Excalibur
Key Veteran
Location: Destination: Earth

My Posts This: Topic  Forum
Quote 
I’ll give you the servo mounting method but the pushrod setup… You found that difficult? I hate sheet metal screws in plastic so I abandoned the plastic t-nuts supplied with the Predator and made my own t-nuts out of aluminum.

That's why I awarded points to the Spectra for servo mounting. I really hated messing with the sheet metal screws into the plastic block to mount servos on the Predator. Trying to position those little plastic pieces behind the servo while tightening the screw from the front was a major pain. As for spacing on the Spectra, most people use a standard size servo and that's how the PEM nuts are spaced on the frame.

Quote 
Again it may have been part of this poorer batch but the solution was to add glass fibre inside along those seams to reinforce them,.. and that may well be worth doing to your new one as a precaution when it arrives.

I will definitely look into this option if the new canopies experience the same cracking tendencies.

Quote 
I am presently in the re-do mode of the build, (after the first test flights showed boom supports buzzing as well as the servo set screws coming out)trying to properly perform the runout on the fan. I've looked in the achvives and can't find a procedure for this task.

Is there a procedure that you the more experienced feel comfortable passing on to a less experienced gasser builder?

Victor - First thing you want to do is clean the tapered mating surfaces of both the fan and engine shaft and check for any burrs or abnormalities that could cause them to fit together improperly. Once you're satisfied with the test fit, apply a small amount of oil to the engine shaft and place the fan onto the shaft with a gentle turning motion as it seats onto the shaft. Turn it several more times to disperse the oil all the way around, then insert the retaining bolt (with blue Loctite) and washer into the fan hub and barely snug it down. Secure the engine in a sturdy vice and set up your dial indicator so that it's just barely on the INSIDE edge of the hub above the retaining bolt. This is your reference or starting point.

With the spark plug and pull start removed, gently turn the starter cog (backside of the engine) by hand and watch the dial. Determine where the "high" spot is by noting the maximum clockwise travel as indicated on the dial. Stop right on this "high spot", move the dial indicator out of the way, then firmly tap on the FRONT of the hub with a hammer and block of wood right where the high spot was. DON'T tap directly on the hub with the hammer, always use the block of wood, and NEVER strike the blades themselves. Remember, you're tapping, not smacking. Set the dial indicator point back into the hub and check the runout again. If it's more than a TOTAL of 0.0015" indicated runout, move the dial out of the way and tap again on the front of the hub at the high spot.

Once you have the runout under 0.0015", snug the fan retainer bolt a little bit tighter, then check again. It will probably be out again, so don't get discouraged, simply tap on the front of the hub again at the high spot and recheck until the runout is where it needs to be. Alternate between checking, tapping, and tightening, until the fan retaining bolt is securely tight and total indicated runout is less than 0.0015". I was able to get mine just slightly below 0.001" without too much effort. After that, your done!

As for the use of red Loctite on the Spectra, use it only where the instructions tell you to. It's always better to try to build a heli with smooth, balanced mechanics that reduce vibrations then to rely on high-strength Loctite to hold a buzzing, vibrating mass together.

Hope this helps. Good luck with the build and keep us posted.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
08-29-2008 Over year old.
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victorb
Heliman
Location: Newark, DE, USA

My Posts This: Topic  Forum		Fan RunOut

Thanks for the reply, I must have heard you through ESP, as your procedure is pretty much as I was able to complete the task.

Only difference was where I took the runout measurement from, is there much of a differencebetween the outer edge of the fan and the top edgewhere the an engages the clutch?

08-29-2008 Over year old.
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copperclad
Elite Veteran
Location: NY

My Posts This: Topic  Forum		hi victorb
you want to take your reading from the clutch end of the hub , either on the outside or the inside , i generally just take a reading from the outside as it is a bit easier , HTH

08-29-2008 Over year old.
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AceBird
Elite Veteran
Location: Utica, NY USA

My Posts This: Topic  Forum
Quote 
then insert the retaining bolt (with blue Loctite) and washer into the fan hub and barely snug it down.

I disagree; never use loctite on a taper lock application. Use a lubricant so you can get the greatest amount of thrust (tension) with the least amount of torque. It is impossible for the screw to loosen if it is torqued to the proper amount.

Blue vs. red; industry standard is: for screws that will be removed and replaced on a regular basis use blue, for screws that are “intended” to never be removed use red. Red is much harder to break free and green is impossible without heat. One other note about loctite; never use it on a flat headed screw where there is more than one in an assembly.

Quote 
Alternate between checking, tapping, and tightening, until the fan retaining bolt is securely tight and total indicated runout is less than 0.0015". I was able to get mine just slightly below 0.001" without too much effort.

Not a bad method … better than most I have heard. But I am going to tell you up front the tapping and winking the fan around as you tighten the taper is just a bit of an exercise. When that fit is tight you can hit it with a sledge hammer and it ain’t a gona wink, no way. So the success is really dependant on how clean you have the parts before hand. If the joint was clean and tight and the result is an unsatisfactory indication then the only option you have is to remove the fan and try again turning the fan to the crank 180 degrees. A taper lock joint dictates concentricity. That is why it is used. Keep in mind that on the Predator the mating of the clutch shoes to the fan is not a taper lock which is precisely why it can go anywhere and does. I don’t know the details of the Spectra clutch mating.

So my method is simple. Clean it, lube it and tighten the piss out of it by hand (do not strike the wrench with a hammer). Now indicate it and see what you got and then make a decision; do it again or not. If you find that a certain relationship between the crank and the fan gives better results, obviously it would be good to make a witness mark.



I can't tell if the hub and the fan are one piece or not. If they are two pieces like the Predator then it requires two indications.

Ace
What could be more fun?
08-29-2008 Over year old.
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victorb
Heliman
Location: Newark, DE, USA

My Posts This: Topic  Forum		Engine Fan Runout

Thanks to all for the input.
Since I'm waiting on the parts delivery it's probably a good idea to go back and recheck the the fan runout on the upper Clutch side surfaces, hmmmm....
I'll let you know the outcome..

Vic

I Have a Love Hate relationship with this hobby, Love to Build, but Hate to Crash..
08-30-2008 Over year old.
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Surfanarchist
Heliman
Location: Alexandria, VA

My Posts This: Topic  Forum		Dial indicator and fan balancer

As I'm reading this I'm getting a greater appreciation for how much effort goes into building this heli.

I'm going to need to buy the tools to do the fan run out and balance. Can you all recommend a dial indicator with base and a balancer that would do this job?

For balancing I've seen the videos of using ice on either end of a mounting fixture as balancer and I think that's pretty slick but I would then still need a fixture to hold the fan. Any thoughts on what I could use for that?

Thanks,

Wayne

"A man's only as old as the woman he feels."
08-30-2008 Over year old.
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Eury
rrProfessor
Location: Ankeny, IA, USA.

My Posts This: Topic  Forum		For a dial indicator, I use one I bought at Harbor freight years ago. I got it, because it was cheap, somewhere in the region of $15 along with the mounting fixture.

For balancing, I use one of these.

http://www3.towerhobbies.com/cgi-bi...?&I=LXD712&P=ML

Nick Crego
08-30-2008 Over year old.
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victorb
Heliman
Location: Newark, DE, USA

My Posts This: Topic  Forum		Fan Runout

Having to get the job done, I needed to get the tools also, so out to Harbor Freight I went, Dial Indicator and Magnetic Base both came to $41.00. Don't take the cheap way out and only purchase the the indicator, unless you have a well equipped shop, go on, you can ask me. The mag Base is well worth the time/trouble and price of gas to make the return trip.
It makes this task a lot easier when you have the tools and the many experienced instructors around as we have on the fourm.

Good luck,

victorb

I Have a Love Hate relationship with this hobby, Love to Build, but Hate to Crash..
08-30-2008 Over year old.
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AceBird
Elite Veteran
Location: Utica, NY USA

My Posts This: Topic  Forum

This is the indicator you want to get not the typical one shown.



The cheapest one you can find will be better for this application then the most expensive one of the plunger types.

Ace
What could be more fun?
08-30-2008 Over year old.
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AceBird
Elite Veteran
Location: Utica, NY USA

My Posts This: Topic  Forum		trouble with photo (deleted)

Ace
What could be more fun?
08-30-2008 Over year old.
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Eury
rrProfessor
Location: Ankeny, IA, USA.

My Posts This: Topic  Forum		I've been using the one that Ace says not to get, and it's worked perfectly for years in this application. Just get what you can, they'll all do the same thing for what we want to use them for.

I have the older version of this one, it works great, and is cheap.

http://www.harborfreight.com/cpi/ct...?Itemnumber=623

Nick Crego
08-30-2008 Over year old.
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Surfanarchist
Heliman
Location: Alexandria, VA

My Posts This: Topic  Forum		Thanks for the input. I ordered the dial gage from Harbor fraight and the balancer from Ronlund. I think I'm set. I'm not sure how I'll utilize the magnetic base as I don't have a metal plate to attach it to but I'm working on a few ideas. I'm loving the fact that this gasser is forcing me to learn new steps in heli building

You guys are great. Thanks for all the good posts and constant feedback.

"A man's only as old as the woman he feels."
08-31-2008 Over year old.
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8 pages [ <<    <     2      3     ( 4 )     5      6     NEXT    >> ]6578 viewsPOST REPLY
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Gasser Model RC Helicopters > Spectra Vs. Predator - Another Perspective
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