Installing a engine

[David the flyer]

Hi I am installing and .61 engine in a second Hand model I brought a yak (55 I think) the fire wall in angled as it should be so that the engine mounts face slight left, but when I fixed the engine to the mounts, the engine faces level if fact it's more slightly up, any tips out there, should I add some more washers to the rear screws so that the engine points down? Or do 3d models have a different engine mounting? Thanks Dave

Edited By David the flyer on 03/10/2010 15:47:30

Edited By David the flyer on 03/10/2010 15:56:36

[Myron Beaumont]

David

Somethings wrong .Never- never has left been incorporated into the engine mount  & up for that matter .Someone made a cock up when building it .Years ago I acquired a Veron Sopwith 1& 1/2 strutter where the builder got the firewall and bearers opposite way round so I kinow the problem

[David the flyer]

Hi there sorry I think I explained my self wrong, it's not the engine mounts, the fire wall has been installed correctly, with a slight angle I.e. The fire wall is at a slight angle so when you install the engine mounts they will be slightly pointing left (front view) and in my book it does say the engine should point slightly down, but my engine is straight, I spoke to a club member and he said that was ok, it's a preference if you want the engine to point slight left and down, his yak, he has the engine in a slight up position, he said it's better for landing? i was just con fussed, thanks Dave

[David Ashby - Moderator]

An angled firewall (and therefore the mount) is normal design trait to counteract torque as you surmise David. Down-thrust is a common feature too but some aerobatic models do have level fit which allows the flyer to adjust the down-thrust according to taste. 

 

In this respect it's probably best to fly the model first and see what you think, adding some washers to adjust if necessary. Some engines do look a little 'up' by a fractional amount yet while up-thrust is virtually unheard of, you still might want to fly the model first and go from there.  

[Martin Harris - Moderator]

Up thrust usually leads to rather nasty trim changes with power so I don't see how adding it would help with a landing. As you reduce power for the flare, it will tend to pitch the model nose down - probably resulting in a rather undignified arrival!

[David Ashby - Moderator]

No one's suggesting adding to up thrust Martin. David is talking about adding down-thrust with washers which is what I was referring to too.  

[Martin Harris - Moderator]

Posted by David the flyer on 03/10/2010 22:32:45:
 I spoke to a club member and he said that was ok, it's a preference if you want the engine to point slight left and down, his yak, he has the engine in a slight up position, he said it's better for landing?

 

[David Ashby - Moderator]

Hmm, I'd be interested to learn the logic there......

[Myron Beaumont]

Perhaps he lands inverted  with the wind blowing from the left.

Edited By Myron Beaumont on 04/10/2010 11:10:59

[Ultymate]

All my aerobatic power models have right thrust ? usually 2-3 degrees is a good starting point, then fly and trim for down or less likely up thrust.

[Chris Channon]

Hi David,

Two degrees of right thrust ( as viewed from behind ) and two degrees of down thrust is a good starting point, fly it and adjust it how you like the aeroplane to fly.

Hope this helps a bit

Chris.

[David the flyer]

Hi thanks for that, what I have done is put two washers on the front engine mount screws to give the engine down thrust, and it all ready has a little right thrust, that should be ok now? I hope

[Biggles' Elder Brother - Moderator]

David, I assume this is an inverted engine? That's why you've put the washers on the "front" mounts? TBH I always put down thrust washers on the firewall/mount bolts rather than the engine mountings themselves as I prefer the engine to sit "flat and square" on the bearers.

 

Or have I misunderstood you?

 

BEB

[David the flyer]

Hello no you are correct, it's inverted, I did not think of putting the washers on the engine mounts that are screwed to the fire wall? What do you think is the best option, I have put them on the screws that hold the engine into place, they seem pretty tight, and the engine is now pointing slight down, what would you recommend? Cheers Dave

[Biggles' Elder Brother - Moderator]

Personally, I'd put them on the engine mount to firewall bolt - but as I say above maybe that's just my habit! I do think it lets the engine sit flat on the bearers which is good.

 

It probably doesn't make any real difference in the end!

 

BEB

[David the flyer]

Thanks for your help, I going to my local model shop tomorrow to pick up some servos and there is someone there who will take a look for me, another opinion I bet lol lol, flying is so much like politics so many opinions, but thanks for your comments, cheers Dave