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SLEC Fun Fly - Lockdown Project


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Hello all

Well I decided to build a SLEC Fun Fly (IC Version) as a lockdown project.

Kit has arrived and Fus is underway. I'm very happy with the kit. Photos later. I have a question regarding engine size. Has anyone fitted and flown one with an Irvine 46 (One with silver carb)? If yes were there any issues with weight and balance?

I have at my disposal an Irvine 46, ASP 46 or an ASP36. the ASP 46 is significantly lighter than the Irvine (which is not the lightest).

My gut would be to source an OS35AX but these are not cheap (if you can find one), so the ASP36 could seem to be a good alternate. But it is already in a Werewolf.

However the Irvine is a very good engine so may be best choice but the question of weight comes in as the construction is light.

Any advice would be helpful.

Cheers

Peter

(Low Pass Pete)

Edited By Low pass Pete on 21/04/2020 09:27:22

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HI Pete,

I cut my teeth on this model and it flew very well - once I had learned to fly it properly. The engine I used in those days was the old OS 40FP. Sadly not been around for years, but that will give you an idea of weight I guess. Instinctively I would say the OS35AX, but if you are experimenting may be the cost is not justifiable.

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Chop 1/2" off the nose, fit the Irvine (and a pipe laugh), is my first thought. It will not be a floater with a big engine but should be fun.

How much lighter is the ASP 46? I'd have expected them to be fairly similar in weight. Does the Irvine have a bigger/better/quieter silencer?

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Ive a Precedent Fun Fly ( it's about 25 years old) which I believe is the same as the SLEC version. I've had an SC46 on a 10x8 shoehorned in with no need for mod, it currently has an ST34 on a 9x6. Flies well with both engines ....... the 34 is more than enough for it, but the 46 is also a lot of fun and ever so slightly ballistic.

The only point I'd make is on fus construction. the formers at the wing le & the had 2 tabs which keyed into slots in the fus which also make a very nice weak spot ....... one heavy dead stick landing and I had a 3 piece fus. If it's still same construction I'd advise a little light glassing over these points

Good Luck

Alex

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Engine choices are:

Irvine 46 - 396 gms

img_6602.jpg

ASP 46 - 339 gms

img_6603.jpg

Silencer options for both above as the mounting is the same:

1. Irvine 46 original - 102 gms

2. Just Engines quit2 silencer - 111gms

3. Original ASP 46 - 89 gms

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So lightest option is ASP46 with original silencer (428 gms). ASP Silencer is noisy so I would reckon to use ASP with original Irvine - 441 gms

Heaviest is Irvine with quiet silencer (507 gms or 498 gms with org silencer). Probably best of the 46 engines.

Have not been able to weigh the ASP 36 as it is still installed but probably similar to the ASP 46 methinks.

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Last consideration is fuel tank. The kit supplies a SLEC Red tank (6oz). Normally I would use a 8-10 oz tank for a 46. So fuel consumption/duration is a consideration. A SLEC yellow tank will not fit unless I do some mods. However that would increase nose weight.

All that said maybe the 36 would be the engine??????frown

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Yes I know I have got the switch cut-out on wrong side.  As a user of mainly inverted 4 strokes that is where I put the switch.  But this is a 2 stroke install with exhaust on starboard sided so will need to put switch on port side and not starboard.sad

Edited By Low pass Pete on 21/04/2020 12:59:13

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Hmm. Got to be the ASP providing it throttles nicely. No surprise the single chamber (loud!) silencer is quite light - it'll be worth the few grams for the JE double chamber job. However if the Irvine is a better runner that would decide it for me.

An Irvine 39 weighs in at 375g including double chamber silencer. I would expect similar weight of the ASP 36. Perhaps a tickle more, the Irvine silencer is quite light.

As an aside, the old split crank style Irvine 46 (with the nice jetstream carb) weighed about 355g without silencer - quite close to the ASP - supplied with a single chamber silencer of similar weight.

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Well I have just test run the Irvine 46 and the ASP46 on a test bench in the garden.

Irvine runs as expected and is a strong contender. Used an 11X8 prop and 10% fuel. However the ASP runs even better. Wonderful tick over using the JEng quiet silencer. So it looks as if the ASP 46 will get the job. Saves about 57gms over the Irvine.

img_6609.jpg

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I would say put the most reliable engine in and not worry about any extra weight and don't cut the front short. If the CG turns out tail light then the extra weight in the tail will be a fraction of the weight needed the other way round. Then if a light engine becomes available the tail weight can be removed. But most models seem to be tail heavy anyway.

Fun Fly planes don't use full throttle as much as other planes ( depending on your style of flying! ) so a large tank may not be needed. The red SLEC one may be OK however th yellow one is ony 1/4 inch bigger in each dimension ( measured on actual tanks ) so it might fit in.

If you need a cheap yet powerful 30 size 2 stroke look around for an Enya 30SS which seemed cheap secondhand at shows last year. Enyas don't wear out and the plain bearing ones have little to go wrong.

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  • 1 month later...

Well here is my SLEC Fun-fly just about complete. Just waiting for some decals from Pyramid Models and then a suitable day for maiden flight. She will have some American Stars and bars and pretend to be a P51! If I could get some lettering she could be called "Lock be a Lady"  I opted for the ASP46 by the way.

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Edited By Low pass Pete on 18/06/2020 11:18:47

Edited By Low pass Pete on 18/06/2020 11:19:28

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My Fun Fly had her maiden 3 flights yesterday. It was a bit windy but it was no problem. Very pleased with outcome. C of G is just a tad behind main spar. I built a battery box for the battery which is accessed via a hatch on the lower Fuselage just behind the servos. I have not weighed her but would estimate about 4 1/2 pound, perhaps a bit less. 

The plan gave no indication on control throws so in traditional Low Pass Pete fashion they have plenty of movement. The elevator will need some change as it was a little sensitive with the current settings and for some reason I had forgotten a set any lower rates.

Great performance and she will happily cruise about on about 1/2 throttle. Good climb rate and a good quick roll rate. So I am looking forward to a less windy session. Very pleased with outcome. A very underrated kit and a pleasure to put together. Just what I needed to while away the time in Lock Down.

Just waiting for some lettering now to add some Nose Art.  Thinking of naming her "Lock be a Lady"  Covering by the way is Oracover Silver and Cub Yellow.  "F" (for Fun) and canopy are Black Solar trim.

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Edited By Low pass Pete on 21/06/2020 03:54:38

Edited By Low pass Pete on 21/06/2020 03:55:26

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Posted by alex nicol on 21/04/2020 10:54:04:

Ive a Precedent Fun Fly ( it's about 25 years old) which I believe is the same as the SLEC version. I've had an SC46 on a 10x8 shoehorned in with no need for mod, it currently has an ST34 on a 9x6. Flies well with both engines ....... the 34 is more than enough for it, but the 46 is also a lot of fun and ever so slightly ballistic.

The only point I'd make is on fus construction. the formers at the wing le & the had 2 tabs which keyed into slots in the fus which also make a very nice weak spot ....... one heavy dead stick landing and I had a 3 piece fus. If it's still same construction I'd advise a little light glassing over these points

Good Luck

Alex

I passed my 'A' with a Fun Fly. I first fitted an Irvine Q40 which was excellent but realy far too much for me at the time and. like you, swapped to a ST34 which I found perfect. I'm all electric now (well, almost) but I still have the ST34 which was the most reliable glow engine I ever ran.

Unfortunately the model is long gone.

Geoff

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  • 7 months later...
20 minutes ago, Matt Carlton said:

Very pretty and nicely built. Mine went very well on an ASP.40 with an 11x5 so I can imagine yours is pretty impressive with a .46!

I did change the wheels to larger ones as I think the kit ones are a bit titchy! 

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Thanks for the comments Matt.  I like your colur scheme the checks are very effective.  My 46 is pretty old but a good reliable runner.  The model has become a firm favorite especially as she was good value.  Such a change from ARTFs.

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