I'm just dieing to see what prop you guys are going to use.

Does the plastic from those handle the fuel?

yes it handles the fuel fine, if i remember correctly guys were using the seal-a-meal for heat sealing

I've heard of fuel tanks made out of aluminum foil contact glued to balsa sheet, then assembled into whatever shape you've got to work with. I think the idea could work if some glass cloth was involved. Making a tank liner with the little neck sounds tricky, though.

Yup, they work well. Mine are made from poly bags and I seal them to shape with a $30 food sealer if they need modification, just like LF mentioned.

Polyethylene is impervious to anything we use. It also has about zero surface energy and doesn't bond with anything we use either, so heal sealing or pressure + elastomers are the two practical choices for sealing.

Apart from working on a couple of prop molds myself (slowly) I've ordered some D speed props from Steve Wilk. I'll have the combo on the test stand about as soon as the props get here.

There is an article at least 30 years old in an RCM I was thumbing through the other day, describing making tanks from lost wax molds. Lost foam should work great for custom tanks.. make tank shape from foam, add nice smooth bits to form neck, glass over it purty-like, then dissolve out the foam. Well, I make it sound quick and easy anyway.

At a recent jet rally, I noticed how many people use pop bottles to satisfy the rigid fuel tank requirement. They are so tough that they apparently often outperform the composite tanks in drop tests - PET is really, really tough stuff to tear apart.

Today I was distracted by another project - I need to finish machine the motor plate before I can carry on anyhow - and that project I am sad to admit is a lekkie Demon. The saddest part is the biggest baddest motor I own is not worthy, but it will make a nice analog to a light .32 powered Delta though, and should hum around north of 100 anyway. At least I can fly it in the community centre behind my house.. gimme a break, I gotta keep those thumbs sharp for the real RC airplanes, right?

MJD

lekkie is cool too! i have a astro 60 cobalt NIB and speed controller, i think it would be a fine SD powerplant[>:] i have a bunch of A123 packs 2350's 60 is rated at 1200 watts continuous[:-]

1200 watts will haul it around with much authority! Which one is is, how many turns? How many cells?

MJD

i have the 13 turn model, and i have six four cell A123 batteries to play with, they are the 2350 Mha cells, i scored a bunch of the 1100 vpx packs as well and use them to run the flight packs, they rock and are easier to place in the planes as well the 109 astroflight chargers with the firmware update to make the compatible go for 50 bucks or so on the forums...., on another note, i bought some G10 .125 composite for motor plates, that stuff is tuff and strong, and hell on cutting tools[:-]

motor box says 32 nicad cells, #24 wire model 6661..

You have to use carbide or abrasive tools on that stuff. You'll kill HSS tools on about the first cut. Also as you likely know it is very important to cut the surface glaze for bonding well - it's not that epoxy to epoxy doesn't form a good chemical bond, but the residual release on the surface can mess things up. FR4 is the same stuff BTW, except flame-retardant. McMaster Carr had pretty good prices last time I checked.

That motor is definitely a sport or aerobatics motor with that kv rating, but..? Here's the closest thing I could come up with that looked promising. Pitch, pitch, more pitch.. I wonder about torque roll at launch. (EDIT - egads look at the static thrust).

MJD

So, you gonna use all those cells? I'd worry about the front half of the airframe ripping off when you punch the tthrottle for launch..

On another note, I got my speed props. Somehow this picture just doesn't look normal, in terms of the relative amount of space each one takes in the photo.. This is an 8.25x10. Steve Wilk says the D speed guys are running 25-28k on these but need to trim them down to keep the rpm up with AMA 10% speed fuel. Might be a hair light, but my engine is bone stock, has a carb (a big carb but a carb), and I'll be running FAI fuel. So I am not convinced it is too small. Does someone jug that stuff I wonder - 70/20/10 methanol/nitromethane/castor?

I'm still worried about the sanity of this whole venture, but I take that as a sign to forge ahead.

One of my sincere concerns is which one of my buddies I can talk into hand launching it. They already wince at .50's. Although.. the engine is a bit in your face with these ain't it?

MJD

It'll probably launch strong at less than full throttle. I would be surprised if either Sig, Powermaster or Morgans didn't carry that mix. The way to go, [I think] is to buy a drum of methanol for $3 a gallon and sell off enough to local flyers to pay for your own flying.

Were I to decide to standardize on say 5% fuel for these, I could buy a jug of FAI, a jug of syn/cas 10%, blend them, then add castor to bring total oil up to 22%; 73/5/13.8cas/7.2syn would be fine IMHO. That's a very easy recipe to duplicate by visiting my LHS.

I wonder at what rpm these things start to come apart at stock..?

MJD

Now that's the attitude of progress.

glad to hear from the basement.. was gonna get cp to meet up there and see if yah were alive still, low nitro will be just fine, ever had the head of the ops engine, i anm wondering about combustion chamber shape and size, i havent pulled the head off my ops 80 df motor either[:-]

Anyone ever notice the sign on the wing of my Banditos? It fit's in this application too.

You charging and getting ready to fly her again Evan?

That was when I took it up to the speed run Vic had. I ran it but decided not to fly it that day...


She gets charged and checked once or twice a year in case I get the bug to go fly her.

in carbon fiber i trust...lol

I wish you would,I would love to see quality new video of her,howling her two hearts out again.

Fitting the engine up to the test stand, plumbing, and not finished the pipe support yet (but I am now).

Also a chance to give the converted tank a go as well. It is leak tested and fuel goes in and comes out the same hole, so dunno what else to be concerened about.

So.. is medium i.e. standard fuel tubing really enough with an engine that eats 3-4 oz a minute?

I'm skeert.. [sm=devious.gif]

MJD

not a problem at all mas alky mas nitro...

Looks good. Is that the recommended pipe for it? Looks smallish with a lonish header...

That is a MACs 1160, and it does look small doesn't it. The header is a bit too long, I will bring the plug-fat bit length to 12" for starters. Just setting stuff up here.

Hmm.. with an 8.25x10 prop I need to trim this down to 7" for break-in according to the rules of break-in by ILJ. That skeers me even more.

MJD

yah!