"scary" prop hub. New one will be heavier duty. <0.5 oz.

just noticed that your engine has 4 bolts holding the case halves together while mine has only three. you must have an older engine? that separate ignition coil should also work with the CH ignition kit. that's what av8tor1977 did with his little 16cc echo.

what brand of 15x8 are you getting 7400 with?? mine will turn a crappy MAS 15x10 at that speed using the stock 8.5mm carb. you might be able to gain a bit with some simple porting. the "don't forget echo" thread has the numbers.

i've flown an 8lb 60" stick with this engine and performance was great, at 6lb you should have a winner!


dave

awesome stuff.

I don,t mean to be critical...but when posting a reply, could you add more to the post besides a reply like "great stuff" take your time and contribute anything that has some help or imfo another person may use. Or just a few words about what you are working on. Thanks Capt,n

ZAGNUT,

I'm going by memory on the rpm. I do remember that it liked the 15-8. When I get the motor running I'll build a sliding thrust stand and take rpm/thrust measurements for all the props that'll fit it.

antslake,

Thanks for the compliment.

Doug

Back to post # 25 I just about missed that question. A pump like a cline may be needed. But I have read where using a small 2oz head tank right up near the engine and level with the needle valve works good. Exhaust pressure is used to pressure-ize main tank. Do some searches...it will be there somewhere. Good luck Capt,n ... Note... 2 tanks are used ,small head and larger main tank

Captn'

Tank arrangement similar to a glow RC helicopter? What about using muffler pressure into the tank causing an explosion? Backflow into muffler......

Doug,

If you don't mind an external arrangement, you could build a simple device that would use slipstream action to create your pressure. This would allow for greater pressure at greater speeds and vice-versa. Some of the Pattern guys from the 70's used to do this...Wolfgang Matt comes to mind. (now you all Know how old I am!) Anyway, just a thought...

Ken

The Iron Bay fuel regulator would solve fuel delivery problems. You can then locate the tank where you please.

Thanks Eagle Flyer,

I'll search the internet tomorrow for that Iron Bay regulator. Never heard of it before. That's what's so great about this site and the internet in general; a wealth of knowledge to be mined.

I have all the radio gear in the Funtana sans engine, batteries & fuel lines. 3# 11oz.

The TIM-6 ignition is 2.9 oz. complete. That could be trimmed to around 2 oz.

I have a carb from an O.S. FX46. The carb venturi measures 0.302" and the stock WA183A Walbro measures 0.28". ?????? What would have to be changed to use this carb?

Now I'm just waiting to get the crank, hub, and muffler back to assemble the whole thing and test the engine and then fly.....

The Iron Bay fuel regulator was invented for glow fueled engines to eliminate delivery problems created by odd tank locations. If you are using a gasoline carb, Walbro or the likes of it you shouldn't need a pumping system as the carb already has one built in it.

www.billsroom.com/pcfs
Jim Cline has the regulator and info on how it works.

[link]http://www.ironbaymodelcompany.com/Webpages/Accessories/Fuel%20Regulator%20Main.html[/link]

and here's the iron bay regulator. looks like the price doubled since it came out, it used to be half the price of the cline.

the cline reg is about 20 grams and the iron bay is about twice the weight. you will also need some kind of adapter for the glow carb and a tank that can take some heavy-duty pressure. ever seen how a YS turns a tank into a football

i think if you add up all the extras you'll need for the glow carb you won't be saving any weight. also, glo carbs can get touchy when trying to run gas through them.

if your stock carb is only 0.28" at the venturi then you might have quite a bit of power to gain by using something bigger, especially if you want to use a higher revving 15x6.


dave

If you are using the TIM 6 circuit, be sure you have it set up for enough dwell. You can do a search here, and find my posts on that.

Good luck, and keep us posted,
AV8TOR

av8r,

Thanks. I used your thread months ago for the first TIM unit. In fact I've read every thread on this forum since I signed up.

As far as the TIM-6, I went to the local electronic store to buy two capacitors. They didn't have them in stock so they tried to order just one. The supplier laughed and said they don't ship quantities of less than 100 so they sent a "sleeve" of 10 "pro bono". The guy gave me one and said the rest would be around 17 cents each. Same with the other resistor, about 5 cents per. The rest of the kit is a few resistors, a hall sensor, and a magnet. Supply your own coil, spark plug boot, connectors and your set. Low $

ZAGNUT,

I think you're correct on the 2-stroke carb not saving any weight. For the complexity, sensitive tuning, unfamiliarity, and cost, I think the Walbro is the best option. You mentioned a DA/3W plug boot would fit the CM-6 plug. Do you know where you can find one of these? I'm also trying to source an old capacitor to plug the rear of the case as you did.

Doug

you probably won't find the plug boot listed on their web sites but if you call desert aircraft or cactus aviation they'll be able to help. should be around $20. kind of expensive for a couple of pieces of stamped stainless and a silicone boot but they provide the shielding needed with the non-resistor CM-6 and don't weigh much. CH also makes a shielded boot for the CM-6 but it is machined and uses a hose clamp......more weight.

as for the old capacitor, i have a room filled with old electronic crap and i only found 2 caps that had the same diameter as the crank seal. they both came from some ancient PC power supply. your best bet is a repair shop that has a good selection of junk to go through. maybe the bottom of one of those asthma inhaler cartridges would work??


dave

If you are cutting off the crank behind the seal like I think, they why do you need the seal at all???? Pop the seal out, and J.B. Weld a .032 or .040" thick piece of aluminum over the hole. That would save a little more weight, and no search for a plug!!

Make sense?

AV8TOR

av8tor,

I know what you are talking about but I was thinking of cutting the crank off at the rear edge of the rear bearing. A light alum cap displacing the mass of the crank would be much lighter and still maintain the case volume.

This is the 2.9 oz. TIM-6. It has a shielded wire already.

Doug...that coil in the photo....do they last long before they burn out? Is it a s model ? I have one simular to it, about 10 years old. I never tried it yet. I got to get the rest of the parts to try it. Thanks Capt,n

That is an "S" coil. They seem to be easy to burn out. Just leave them charged too long and viola!!!! In the "scratch built ignition" thread there was mention of a latching switch that sounded promising. It would determine dwell time and would discharge the coil after that pre-set amount of time. No more sensors being accidentally closed and burning up coils.

Doug

How would I tell if mines is a "S" model or just a regular one. I am sure they made 2 or more with differant spec.s Thanks Capt,n

Well, it's been a while. ANeat finished the muffler and prop hub and did a fine job. Now I'm waiting for the titanium bolts. Here is a pic of the two items. The sand-blasted muffler weighs 1.3 oz and the "un-scary" prop hub is 1 oz.

The titanium bolts came in today. The steel bolts weigh 3.2 oz. Titanium are 1.4. Not bad for $30.

nice! almost 2oz saved from just swapping bolts. i would have thought that only those cheesy aluminium bolts would accomplish that.

do you have a link for a web site?

dave

I found 3 places:

mettec.com
unitedtitanium.com
racebolts.com

I ordered from racebolts. Mettec was a couple bucks cheaper but I liked racebolt's site better.