Newbie Seeking Advice Please.

[John Roberts 9]

My Irvine Tutor Mk.2 is almost built but there are a few small things that I need to resolve before the maiden flight and I would very much welcome advice from some more seasoned flyers please.

 

First, will an 11 x 7 prop be ok with an Irvine 40 IC engine or would another size be more suitable?

 

Second, what settings (needle jet and carb) should I be using to start the engine for the first time please? The engine is approx. 10 years old but has never been started before and unfortunately I no longer have the instructions (they were lost, along with most of the other contents of my garage, when a huge tree was blown over last winter!).

 

Finally, what is the running-in procedure for the engine please? As I understand it, these engines need to be run at quite high revs in order to get everything hot as quickly as possible. Is this correct? I really would appreciate an idiots guide setting out precisely what I need to do please.

 

Thank you in advance for reading this and for any guidance you are able to offer.

[Biggles' Elder Brother - Moderator]

Hi John,

 

a few quick pointers and I'll come back with some more detailled stuff if you need it. I don't have an Irvine 40 manual so most of this is "by feel" rather than fact - maybe someone with a manual could check me out!

 

An 11x7 is a bit big I would have thought for this engine. It might be happy with it but I would guess it would be happier on something sort of 10x6 size.

 

For first run the needle is usually best around 21/2 to 3 turns out. You want it a bit rich.

 

Regarding the low end needle - usless you know it has been moved I'd leave it alone for now. We can come back to it if its proving troublesome to start.

 

Assuming the Irvine 40 is an ABC engine then yes short runs at max revs are the order of the day for running in. But I am really loathed to give too much advise on that as you really do need it from the manual or someone who has run that specific engine in sucessfully.

 

BEB

[Frank Skilbeck]

I have the instructions for a Mk III 46 ABC if that's any use, pm me if you'd like me to scan and send then to you.

 

But basic running procedure for a 46 ABC from the instructions is as follows

 

"ABC engines should also be run in at full throttle but with a far less rich mixture than a ringed engine. In order to operate correctly the ABC piston/liner must be brought up to operating temp quickly. JUST breaking into clean two stroke running is about right for initial running on an ABC engine (this is the crisper exhaust note and quite a significant jump in power). If an ABC engine is run too cool (rich) it will try to sieze itself just as it would if were too lean. Run the engine for short periods of two to three mins with intervening cooling down periods"

 

A tank full like that and you should be good to go.

 

PS I would think a 10 x 6 or 11 x 6 is more appropriate an 11 x 7 may overload a 40 and cause overheating

[PatMc]

There were 3 or 4 versions of the Irvine 40 the main difference being ABC or ringed. I've had a couple of ringed 40s & one ABC 40. In operation, once run in, they can be treated identically.

I still have the ringed version instructions handy if you want a scanned copy but the ABC engine & instructions are somewhere in my loft.

 

Here's the prop recommendations verbatim from ringed engine instructions -

 

Propellers: The choice of the right propeller depends as much on the aerodynamic properties of your model as on the power of your engine. The following recommendations are intended therefore only as a basic indication. Which size and pitch of propeller is best suited to your model has to be established by flight trials.

10x5, 10x6, 11 x4 for aerobatics.

8x8,9x7 for general U.C.

7x10.5, 7x11 for speed.

 

(U.C refers to control line.)

 

Last model I used the 40ABC (after I'd worn out the first ringed 40 in it) in was my Priory Silhouette. I tried a range of props from 9x7 (3 bladed) to 12.25 x 3.75 without any issues.

 

IMO an 11x6 would be about right for the Tutor but an 11x7 wouldn't be much different.

 

If the ringed engine instructions are any help I've also got a photo copy of Peter Chinn's Engine Test report for it from the Feb 84 issue Radio Modeller.

 

 

[Flanker .]

Find a club, join it. Talk to the members and find their engine person - there often is one and ask them to help out. By far the best way to avoid tears and frustration. If no club the above advise is all good.

 

Good luck matey, F

[John Roberts 9]

Thanks to everyone for the helpful replies.............I now have all the information I need .

 

Judging by the 5 day weather forecast it could be several days (or more!) before I can get my maiden flight but I guess that gives me some time to get the engine run in and everything else set up (hopefully) perfectly.

 

Thanks again for the very prompt & helpful responses.