Hope someone can help a complete novice (rc plane idiot) I broke the 3 blade prop on my alpha 60 trainer and could not get an exact replacement, so the tech at Horizon reccommended a 12x6 prop. Went to the local hobby store and bought two APC 12x6 props. Dang! wouldn't fit on the 3 blade spinner. Went back to the hobby store and bought 2." dubro spinner, went back home.
On the back plate there is small post that presumably the trailing edge of the prop is suppose to rest against. Unfortunately, the prop doesn't fit properly and I can't get the spinner to fit. I've carved a little on the spinner to try to get it to fit, but it looks like I really need to cut off the posts or grind a groove in the trailing edge of the prop so it will fit.
My question is this: Is it safe to remove the posts on the backplate of the spinner so the prop will fit right?
It won't make a lot of difference if you can get the spinner carved out to fit the prop. I suggest you take the plane and spinner to the shop and have them show you the proper way to do it.
Simply replace the plastic spinner with a 'spinner nut' instead. Much easier to live with, unless you want to use the cone type spinner for aesthetic reasons.
No difference at all other than throwing the whole thing out of balance. But if you don't mind taking the chance of vibration destroying the model, go for it! Just don't run the engine around me.
Sounds to me like you need a bigger spinner. A 12 inch prop sounds to be on the large side for a 2 inch spinner. Or, fly it without a spinner. Nothing saying you can't.
On 5/6/2004 12:22 AM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:
If you decide to do as Mr. Bonk suggested, Use a prop nut instead of the spinner, just reverse the rubber cone in your electric starter. After you take the rubber piece out of the metal housing (it pulls out - may need some silicone lube to get it loose) you will see a small hole on the bottom. Put the insert back in with the small hole facing out. The small hole goes over the nut and the rubber presses against the prop blades to start the engine. Sounds complicated, but it isn't.
Another option is one of the "Higgley" brand "Hubs". Do not get the heavy hub, just the regular one. These are threaded and you uses them just as you would a prop nut, but they are rounded. If you decide to do this, I suggest bringing the starter with you to make sure the insert on the starter will grasp the Higgley properly. They also make different size inserts in case yours is too large.
Don't grind a groove in the prop! You don't want the blade to fall apart when it's being spun at several thousand RPM.
I usually try to keep the posts and carve in front of them. But I've broken the posts with backfires, tightened everything up OK, and then continued flying with the "broken" spinner.
Do your best to take the same amount of material from both sides of the spinner.
Don't let the spinner touch the prop at all--carve enough away from the prop so that it's got a little clearance all the way around the opening in the spinner.
I use a Dremel tool for enlarging the spinner openings. If you use a knife, watch out for your fingers. Don't ask me how I got so shmart. :o(
I wouldn't. DO NOT carve or cut on the prop AT ALL! You basically have two choices.
Buy a larger spinner. You may have to cut out the prop openings in it. If so, be sure no part of the spinner cone touches the prop. If it does, vibration will quickly wear a groove in the prop that will cause it to shed a blade at some point. VERY DANGEROUS.
Ditch the plastic spinner and go with a "Safety Nut" like Higley or Great Planes sells. As someone else suggested, if you do that, reverse the cone in your starter so the small hole faces outwards. Dr.1 Driver "There's a Hun in the sun!"
Are you going to tell everyone that EVERY prop and spinner combination you ever bought fit right out of the box? Most all plastic spinners come cut out for the minimum prop size. Almost all of them need to be carved out to fit properly. Done right, there is no more risk with them than with stock.
I have never "carved out" (your words) the openings of a spinner. I either purchased a bigger spinner that would fit the prop out of the box or I would fly without a spinner. Or, in the case of Tru Turn spinners I would get the existing cone modified by Tru Turn or a new cone made with larger openings. Why? Because Tru Turn balances their spinners! Duh!
But unlike you, I would not recommend to "a complete novice" (his words) to go hacking on a plastic spinner. Especially without telling him the need to properly balance the spinner as well as the prop. You are simply asking for an accident! But from you Paul, I expect as much! You're obviously about as safe as a condom that's open at both ends! Stay clear of my field!
And you only show up when you can make an ass out of yourself. I see very little from you in the way of help here, only criticism. Your flying site must be a very lonely place.
Note that I am not front-posting :-) (nod to a previous thread)
On every plastic spinner I have ever had, I have carved out the openings to fit the prop. I do it as carefully and symmetrically as possible, then go fly. (For metal spinners, I am a little more careful - I use the Top Flite magentically suspended balencer). I don't seem to have problems, and it lets me build ARFs with the spinner in the box.
The main failure mode for plastic spinners seems to be a backfire that breaks the spinner apart. These occur when starting, not when the engine is at full song. In one case, the pieces were about 50 feet apart.
On the back plate there is small post that presumably the trailing edge of the prop is suppose to rest against. Unfortunately, the prop doesn't fit properly and I can't get the spinner to fit. I've carved a little on the spinner to try to get it to fit, but it looks like I really need to cut off the posts or grind a groove in the trailing edge of the prop so it will fit.
My question is this: Is it safe to remove the posts on the backplate of the spinner so the prop will fit right?
Thanks! ==================================
Definitely do not grind the prop, it will cause it to break.
A 2" spinner is tiny for a 60 size trainer. I had a Great Planes 3" aluminum spinner on my Great Planes PT-60 and it cleared a 12x6 prop with no issues. I 'landed' nose first a few weeks ago and broke the spinner. Now I'm using a Higley aluminum acorn nut and am pretty happy with it. Dubro sells aluminum 'spinner nuts' that are cone shaped and are supposed to work with standard starter inserts. I have one somewhere; maybe I'll dig it out and install it.
My 'landings' have cost me either 3 of these aluminum spinners; I'm not rich enough to keep replacing them.
To by a spinner that fits a 12" prop would mean buying a 3 1/2" spinner. That might look a bit funny with a 1/4" or more hanging out the side of the fuse. I would rather buy a smaller spinner and carve it out.
Me thinks you need to do some high altitude SLOW flight practice so you recognize when the plane is about to STOP flying and fall. Then you might think about the approach to flare a bit so you are ready next time. Dissertation follows.
Before you do any of the following steps, make absolutely sure your CG is correct. A tail heavy plane will fly, just not for as long as a slightly nose heavy one.
Set up the needles so the engine will idle for 3 to 5 minutes and not die when you hammer the throttle. This is the most important thing you MUST do for it will mean learning or praying you can flare properly if the engine dies.
Take off and turn when there is daylight between the fuselage and the horizon. When the plane is 45 degrees to you turn (down wind leg) and check to see if the elevator is trimmed properly. If it is, hammer the elevator (with the throttle still at full) and hold it until the plane is back level. If it will not complete the loop, recover and land carefully because you have a dangerous situation that must be corrected.
If the plane snaps out of the loop you have too much elevator throw or the bird is tail heavy. Since you have already checked that, reduce the elevator throw and return to the prior test.
Once the plane is capable of a complete loop, under control, you are ready for the next step.
Begin this step at altitude - 4 mistakes high the first time or two until you get comfortable with the procedure. Once high enough, turn from base to final leg and pull the throttle at the same time. Do not let the plane come down rather feed in enough elevator to keep it going level as the airspeed decays. The goal here is to be able to see the plane stall about the same time (or just after) the elevator stick reaches full travel. If the plane falls off before you get that slow, you are probably slightly tail heavy and than should be corrected.
Once you can get the plane to fly in the above condition, practice a few circuits of the airfield at that altitude, airspeed, and without loosing altitude. It is HARD work but the knowledge you gain will be priceless later on.
That is the beginning of learning how to land. The next steps have to do with learning how to set up the approach and flare which is where most beginners break props.
Turn final, cut the power and allow the bird to come down to shoulder level before you begin much in the way of elevator control (I teach at a SMALL and TIGHT field). When the plane is at shoulder level, begin to gently bring the nose 1/2 way up from where it is to level. The plane slows down its descent. When it reaches waist level, slowly and gently bring the nose 1/2 the remaining way to the level and hold it there. As the speed decays the plane will begin to sink. When it gets to knee level the fuselage needs to be gently and slowly brought to level. At any of those places where 'gently and slowly' was used you jerk the elevator, the plane will balloon and MOST folks dork it in right there. This is one good reason to practice slow flight so you get knowledgeable about control responses when the bird is SLOW.
At knee level with the fuselage level, the plane will slow and sink. As it sinks, gently pull back to raise the nose and arrest the sink. Keep this up until the wheels are on the ground.
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