Engine mounting

[Michael Hambleton]

Hi guys, i'm putting together what is my second ARTF, I have secured the engine mount to the firewall, I then mounted the Engine and bolted it down, that looks good i thought, until i viewed it from the side the engine seems to have a downward pitch at the front!! having unbolted the engine and tried it at various points along the mounts it will not sit facing straight. Will this downward pitch at the front make a difference to take-of, flight and landing? or is it supposed to be like this?

Grateful for any help or advice.

Mick

The engine is an SC46...(not what was reccomended not sure if it makes a difference?

[Myron Beaumont]

Don't worry Mick
Downthrust (about 2-3 degrees is normal ) as is the same amount of Right thrust as well (all depends on the A/C)
Grumpy

[Grant Darnley]

Don't worry about that SC, the TT is quite a slow flying plane and you can always throttle back.

[Tony Fransens]

I noticed that on some plans there was no indication of putting the engine under an angle not up or downwards nor sideways.

Fellow clubmembers give me contradictory information about this matter.

Do you always have to give 2 to 3 degrees downtrust and the same angle sideways to starboard, or is this diferent from one model to another.

Can sombody please give me a good explanation?

Thanks,

Greetz

[Former Member]

[This posting has been removed]

[Tony Fransens]

Thanks Eric!

[Roger Yeomans]

I have problems mounting SC46 to my Arisingstar.Following the instuctions I mounted engine 11.2cm. from fire wall useing 3x25mm bolts as per instuctions { bolts not in kit or engine box , a bit naff } . The bolts come out at the back of mount on an angle piece of mount . The back bolts are then too short , the front ones wont take nut because of angle of mount. Seems a bit of a mess, more so when you consider that plane is a trainer for beginners such as myself. any suggestions?.Cheers Roger.

[Ernie]

Hi Roger,

I use good quality self tapping screws (there are some nice ones with an allen key head) Put a locking washer between the screw head and the engine lug..No problems over the years. If you are a belt and braces sort, then a squirt if medium cyano in the hole might help. Not to glue the screw in, but to harden the surface of the hole 

ernie

[Roger Yeomans]

Hello Ernie . Thanks for that. Trouble is I drilled holes to 2.5mm and screwed in the bolts before I realised they are too short. So now I won't be able to use self tappers, will I?.If I use thread lock I'll never get the engine out should I need to.The only solution I can think of, is to drill out the engine mount [ underneath ] to take bolt head . This will reccess the bolt head , makeing it in effect longer and hopefully seat it flat , enabling a nut to be screwed on the top. What do you think?. Cheers Roger .

[Ernie]

Hi Roger,

Sounds OK, but the hole would need to be big enough to take a washer, or the bolt head would cut into the mount, I assume the mount is plastic.

ernie

[Lord Lucan]

You could always use a pair of longer bolts instead.

[Roger Yeomans]

Hello Ernie Hello M,Lud.Yes the engine mount is plastic. The prolem with longer bolts is the nuts won't seat flat and square because of angle on underside of engine mount,I'm concerned that they will work loose.Any other ideas. Thanks Chaps.

[Steve Hargreaves - Moderator]

I think, Roger, you will have to try & find some correct size self tappers or replace the mount with one that has nice flat beams top & bottom. Ripmax do a nice adjustable one which would help in matching the mount holes in the plane.....

 Hope this helps.....

PS if you've drilled the mount M2.5 this is the correct tapping size for M3. If you have a proper tap (rather than just forcing the bolts in) then IMHO 4 x M3 bolts screwed into the mount should be enough to hold a 46 in place.....put washers under the bolt heads though.....

[Phil Claridge]

i have used that method without tapping umpteen times never had a mounting split or the bolts work loose usually crash the plane before that happens you can use a power drill with a straight allen key to wind the bolts in if you go slowly

[Roger Yeomans]

Hello Steve and Phil . I have wound the bolts in , they just make it to bottom of mount. Do you reckon this will be strong enough?.There isno room to wind a nut on .Obviously I have never flown it or any other plane, so chances are I'll crash it but would like to make sure it's safe.My grand children will probably be there , and wanting a try.I also have a Topgun Piper Cub [ 80" scale ] , that was alot more expensive, hopefully it'll be a better model to put together. I thought I'd learn on the 'star and save some money,if you know what Imean. Let me know if you think I'll get away with my current fixing.I need all the help I can get. I have some plans for a VERON glider from late 50s early 60s if anyone is interested[ details on request ] . Thanks for your help. Cheers.

[Steve Hargreaves - Moderator]

Difficult to say without seeing it. I always tap my nylon mounts but use the correct size drill, ensure it is 90 degreees to the beam (so the hole is straight) & use a proper tap. The glass filled nylon of the mount holds a thread quite nicely so done this way I would see no problems (& indeed have never had one)

BUT (& please don't take this the wrong way & I'm not being disrespectful) if the hole is at 75 degrees to the beam, drilled oversize with an oval drill & tapped by forcing a cross threaded old bolt into it then I would anticipate problems!!!!

If yer holes are nearer the top example than the bottom then it should be OK....I guess you're learning with a club so maybe let one of the guys there take a look & offer an opinion......if there's any doubt then I would suggest you bin the mount & buy a new one...the last thing you need is an SC46 turning an 11 inch prop at about 10,000 rpm leaping about the pits!!!!! Wouldn't make you very popular.......