Jason’s Firefly .46 Build

[JasonBModerator @jasonb]

Looks good.

Assuming you are just going to run it for the satisfaction rather than need any performance then any glow fuel will do, you don't need a high nitro content so 0-5% nitro would be more than adequate. Run it on the rich side to start with until things bed in.

I went with teh OS No 8 plug which is a good all rounder and a 10" dia x 7" pitch prop.

[Nick_GParticipant @nick_g]

Posted by geoff walker 1 on 09/04/2017 16:03:20:

I have never started one before so I am now on another learning curve.

.

If you have any problems give me a shout due to me being very local to you.

I spent quite a bit of time years ago with RC aircraft and engines. There can be a bit of a nack to them and it's easier to show someone than trying to explain. After that it's like riding a bike.

Nick

[geoff walker 1Participant @geoffwalker1]

Thanks Nick.

I'm going to to set it up on a test bed

Will give you a ring later in the week to set up a visit to yours.

Be good to see the Hit and Miss while I'm there.

geoff

[geoff walker 1Participant @geoffwalker1]

Hi All

First run of the firefly, not to bad a couple of compression leaks otherwise ok.

Can't figure out how to paste youtube link, too hard for me.

If your interested look for whittaker firefly 46. —-uploaded by bobbie jones cheers geoff

Edited By JasonB on 14/04/2017 20:17:17

[JasonBModerator @jasonb]

Looks to be running well

[Nick_GParticipant @nick_g]

.

Well done that man.!

Nick

[Neil WyattModerator @neilwyatt]

Sounds good!

neil

[Keith WhiddettParticipant @keithwhiddett67769]

Hi would some body be kind enough to tell me where I can get the plans for this engine,please

[Thor 🇳🇴Participant @thor]

Hi Keith,

They used to be available here, I think I have them on my computer hard drive somewhere.

Thor

[geoff walker 1Participant @geoffwalker1]

Hi Keith,

You can't get them free on line now, you may have to buy them!!!…..my hobby store plans service?

Ebay Item number 162651802036. may be of interest to you, R c m and e magazine feb 2012.

geoff

[JasonBModerator @jasonb]

Keith check your messages, flashing envelope at the top of the page.

MHS plans service is no more.

[Keith WhiddettParticipant @keithwhiddett67769]

many thanks to Jason for the thread as that was all I had except for the plan . Engine mount wood is flexing hence movement

**LINK** https://youtu.be/DQ_LxO-p75s

My first attempt at an ic engine, very please with result, it’s not exhibition standard but it runs and looks ok.

 

 

Edited By JasonB on 20/04/2018 18:10:02

[JasonBModerator @jasonb]

You have done a good job of that Keith.

J

[Keith WhiddettParticipant @keithwhiddett67769]

Thanks for like Jason. What I did not add is that I ball raced the main shaft !!

[geoff walker 1Participant @geoffwalker1]

Nice job Keith, I know how you feel, it was my first engine as well.

I also used ball races instead of the plain bronze one. No particular reason just seemed like a good idea.

Mine has been in the air today on a cougar 2000 model. The slightly larger carb is one I made for Jones 605, easier to tune for performance. Just about fits in the barrel space. The Cougar is a small light model which was about the size limit for my engine.

Geoff

[Peter Wood 5Participant @peterwood5]

I have just completed my Firefly relying heavily on Jasons build thread. Thanks Jason.

Since I have plenty of spare material left I am thinking of making another but this time with beam mounting lugs and learning from some of my mistakes.

One of the most difficult tasks was pressing the silver steel crankpin into the crankshaft web as it kept going off square in the mill vice.

In the RCME article by Frank Payne he suggests using a roll pin for the crank pin!

Has anybody any experience of this method?

Peter

[Neil WyattModerator @neilwyatt]

Nice engines Geoff, Keith

Neil

[geoff walker 1Participant @geoffwalker1]

Well done Peter,

I'm glad I'm not only one who made mistakes making this engine.

I eventually took mine apart re lapped the bore and made a new piston and con rod, to improve the performance. I cu'd the lapping of the piston into the bore first time round, second piston was a much better fit.

How about some pictures of your engine, love to see some

Geoff

[Keith WhiddettParticipant @keithwhiddett67769]

Hi Peter, I would suggest your tolerances were a bit tight regarding the crankpin,I put a small chamfer on the pin to enter the hole and froze the pin, locktite the pin. Make sure every thing is perfectly square when pushing in the pin.

You could of course turn the crankshaft including the pin! I ballraced my engine a very worth while modification

Good luck.

[Ian HewsonParticipant @ianhewson99641]

Just received the plans and ordered some metal to make a start on Firefly, can you say how the ball races were fitted and the type?

This will be my first ic engine, all my others being steam, looking forwards to the build.

Just a note that John Feeney is no longer supplying the metal kits for this engine.

Edited By Ian Hewson on 24/11/2018 11:34:29

[Peter Wood 5Participant @peterwood5]

Keith

I think you are right. I used 7/32 silver steel for the crankpin. I did not want to turn this down but was also scared of drilling the hole in the crankweb too large and having to start again. So I drilled the hole 13/64.Obviously too tight!!

Next time I will take a 7/32 reamer to the 13/64 hol but not take it all the way through. Also I will freeze the pin first and possibly heat the crankshaft with a hot air gun.

Geoff

I am going to make another piston. Like you I got carried away with Jasons brilliant reamer design having already made the piston. Also I had three attempts at the con rod eventually rounding the ends with filing buttons, but was pleased with the final result.

At present it has a prop driver and carb from an ASP 46 until I know it runs when I will make a new one.

Perhaps a photo later although it is not exhibition standard.

Peter

[JasonBModerator @jasonb]

Ian, there are no ball races in this engine.

You can ream the crank pin hole using a hand reamer and take advantage of the reamers taper so that the pin will start to enter the hole but is then pressed into an ever tightening tapered hole which helps keep it lined up

[Ian HewsonParticipant @ianhewson99641]

Hi Jason

A couple of people have mentioned fitting ball races as an improvement, wondered if it is worth while?

Would you have the glow plug type handy, never had any experience with model aero engines, but it seems that the glow plugs react similarly to spark plugs in a tuned car engine.

Ian

[Peter Wood 5Participant @peterwood5]

Ian

An OS # 8 would be a good starting point. I use them in most of my 2-stroke aero engines.

Peter

[JasonBModerator @jasonb]

Yes OS #8 was what I ran mine with.

As to bearings, I suppose it depends on what you want to do with the engine. For me just the odd bench run is all it will get so the bronze ones are fine. A bit of gentle flying will also be OK with teh bronze it is only if you want to push it harder that ballraces may be worth thinking about.

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