OK, this might be a silly question, but... is there any specific way to bolt props on? Is there a certain way to align it with the compression etc..? I have a saito 45 and after running it for a few minutes, my engine mount bolts were coming loose. As a side note, how would you go about replacing blind nuts in the firewall if you really cant get to them with out taking half the plane apart?? Thanks,

Mike

Not a silly question ....

why do you want to replace the blind nuts?

Use the blue lock-tite on the engine mount bolts.

Most people align their prop so that it is horizontal as the engine compression starts. When the engine "dead-sticks", the airflow will "windmill" the prop untill the engine starts compressing, at which point, the prop will be horizontal, which lessens any chance for prop damage in the event of a hard dead-stick landing.

Some people believe that the prop can be used to help "balance" the engine ... but there is a lot of controversy about that.

Regardless, the prop should be VERY tightly attached. Get a regular spanner/wrench that fits your prop-nut. Use one habd to hold the prop, and the other to hold the wrench. Tighten the nut until you think that the prop is going to cut your other hand. Then tighten a bit more.

gus

If the engine mount screws are coming loose it may be due to unwanted vibration, possibly caused to unbalanced prop. Balanced props are highly recommended. Thread locker is also a good idea as gus pointed out.
I would like to say I have read article about using the prop to help balance the engine, but the engines they were referring to were the old cast-iron cylinder engines like the old Fox, todays engines are much more precise and don't really apply here. FWIW

Just another note.... people who hand/chicken-stick start their engine often align their prop so that the prop is just like I said above, because it means that you can get the most "stroke" accross the prop as you start it.

gus

The blind nut question is because one of them has pushed back from the inside of the firewall, and I could not get it to pull back into the wood while tightening it. I will try again tonight, but if it doesn't work I don't know if I can replace it. For reference it is on a telemaster, and there doesn't seem to be any other way to get to it except try to pull the tank out etc...

also good position for belly landing

If you're having vibration problems, balancing the prop is a first step. After that, aligning the prop with the piston, ie the prop is vertical with the piston at TDC, can help reduce vibration. If you have a slightly heavy blade, you can align it downwards with the piston at TDC to help a bit. But it's easy to over-due, and hard to get exactly right, which is why it's usually best to just balance the prop and put it on where it's convenient.

Btw, even "modern" engines are almost never "perfectly" counter-balanced internally. The crankshaft balance is always a bit smaller than it should be in theory. There are all kinds of things you can do to the innards of an engine to improve the balance and reduce vibration, but unless you're really pushing for high RPMs or you are just obsessed with vibration, you don't have to worry about it. However, it is true that the lighter Al pistons in a typical engine these days does mean less vibration than an iron piston.

Oh, as for me personally, I just slap it on there and where it is, it is. I use an electric starter, so starting isn't an issue, and frankly I don't break props, even on my gear-less combat planes. If you set it down softly enough, the prop will move out of the way of the ground and not break (works better with MAS props though).

My Telemaster is rigged so the top panel of the fuse, from the firewall to the front of the windscreen, is removable. I can get to the tank, the battery is in there, and to the backof the firewall. Two screws hold it in place. It's a great access hatch, you might consider modifying yours.

rrh

Replacing a blind nut in the firewall can be a royal pain...


If you can run a straight wire back into the wing opening from the bolt hole... you put a 90 deg bend in wire that JUST fits inside the screw threads. put the blind nut n the wire so the flat is to the bend... run it through the hole fromthe back (may need another wire and heat-shrink tube or tape to guide it in some cases) and pull the blind nut firmly into the firewall. (now get the wire out without knocking the nut free again...)

You can also use threaded rod... similar trick, but if you put vaseline on the rod... you can put some 30 min epoxy on the blind nut and tighten it in place till the epoxy cures.

If you've got some mild curves to negotiotiate... nyrod and a piece of 2-56 threded rod (the 2 inch pisece you get for a pushrod end) put a 2-56 nut between the blind nut and the nyrod... push the nut in place. Again vaseline can allow use of epoxy to hold the nut firmly. (you can use washers and another nut to pull the blind nut firmly into the plywood.)

From there... its all variations on a theme.. when REALLY desperate... you can file the head off of a correct size screw... file flats on opposing sides and drill for fishing line to pull the thing in with. (and that's also how you make a 4-40 threarded end for scale rigging....)

RRH,

How hard would it be to make the modification. I'm working with very limited experience, but I'm willing to give it a try. I have other models with a hatch like that, but I didn't know if there was a reason the Tele didn't have one, or what. Do I just cut the top then make some kink of interior rails that it would sit back on and drill a couple of holes for screws??

That's exactly what to do Turtle. And make sure to fuel proof the newly cut balsa.

BTW, I set my prop so it hits compression at about 1 to 2 O'clock. It's just a more comfortable "Flipping" position for me.

Thanks for the help guys, one more question...will fuel proofing that area add enough weight to change the CG at all??

Not significantly, but check it anyway.

gus

The added wood and fuelproofing from putting in the hatch... I'd be suprized if you put in more than 1/4 oz And since its forward of the wing, right over the fuel tank the cg change would be like having 1/4 oz fuel in the tank. (that doesn't make a big difference in how a plane of the Telemaster's nature flys) I wouldn't bother reballancing.

Thanks everybody for the info...this site is a great help to me...I just got my AMA card in the mail today, so weather permiting I will be headed to the local flying club this weekend. I also posted some pics of my P51 that needs some attention to get it back in the air. It's in the beginners forum under "what to do" b/c the covering, what ever it is is in bad shape in a couple of areas. Take a look if you get the chance. It has an OS 61 in it...if I remember correctly it is really fast and doesn't like it when I fly it[>:] I only flew it once or twice before I got out of the hobby for awhile (college and Navy) Well anyway, just wanted to say thanks to everyone who gave me info/advice...THANKS