Author Topic: Pusher tank configuration? (Read 5867 times)

Avaiojet · « **on:** January 10, 2017, 06:27:31 PM »

Well, I said I was designing a stunt biplane a year or so ago and I did mention it would be a pusher.

I have much of it designed and could start cutting wood by the end of the month.

How does one set up a tank when it is in front of the engine? I expect to use a round Sullivan tank because I have one.

Thanks in advance.

Charles

Steve Helmick · « **Reply #1 on:** January 10, 2017, 08:55:12 PM »

Would require a custom made tin tank (or some serious plastic tank revisions), because it would still need the fuel pickup at the outboard rear of the tank, and the fuel feed line would also come out of the back of the tank.

Is this going to be a canard biplane, by any chance?

Steve

Avaiojet · « **Reply #2 on:** January 10, 2017, 09:59:41 PM »

Quote from: Steve Helmick on January 10, 2017, 08:55:12 PM

Would require a custom made tin tank (or some serious plastic tank revisions), because it would still need the fuel pickup at the outboard rear of the tank, and the fuel feed line would also come out of the back of the tank.

Is this going to be a canard biplane, by any chance? Steve

Steve,

About the tank, that's what I thought. I could play around with a tank and eventually get it. I can buy copper tubing at Brodaks.

No, no canard up front, just a couple of wings, pusher prop and try gear.

I've outdone myself, not difficult actually

, with this design.

48" in span. It's really really nice.

Thanks for the reply.

Charles

Lauri Malila · « **Reply #3 on:** January 10, 2017, 11:53:59 PM »

It woulg be interesting to see how it behaves in an aerobatic model. A big part of 4-2-4 run comes from changing tank position (in relation with spraybar). Now, I would think that engine goes rich when you raise models nose. L

Paul Smith · « **Reply #4 on:** January 11, 2017, 02:24:52 PM »

I like the Curtiss Pusher. Among other things is the problem of flipping the prop.

I guess it would be necessary to have special starter with a long shaft made.

phil c · « **Reply #5 on:** January 11, 2017, 08:05:39 PM »

I'd start with your bottle tank mounted normally, with the cap in front. Run the fuel line back, using some clip to keep it from flopping around. As long as you don't introduce air bubbles from vibration the length of the fuel line usually doesn't make a huge difference.

Steve Helmick · « **Reply #6 on:** January 12, 2017, 03:07:14 PM »

Quote from: Paul Smith on January 11, 2017, 02:24:52 PM

I like the Curtiss Pusher. Among other things is the problem of flipping the prop.

I guess it would be necessary to have special starter with a long shaft made.

R/C helicopters apparently use a long shaft attached to a normal electrical starter. This becomes a problem when the switch does not shut off the 'lectric motor after the starting chore is done. Whips around like the dickens, I was told...not good.

Steve

Mark Scarborough · « **Reply #7 on:** January 12, 2017, 03:39:39 PM »

I am just guessing here, but you mya just have to figure it out,, not a lot of airplanes with tanks in front of the engine, ( at least control ine) but then hey, your a modeler, and a modeler should be able to figure it out

maybe talk to some of the scale guys,,

Avaiojet · « **Reply #8 on:** January 12, 2017, 06:28:29 PM »

Quote from: Mark Scarborough on January 12, 2017, 03:39:39 PM

I am just guessing here, but you mya just have to figure it out,, not a lot of airplanes with tanks in front of the engine, ( at least control ine) but then hey, your a modeler, and a modeler should be able to figure it out

maybe talk to some of the scale guys,,

Mark,

Thanks for the reply.

I ran pumps on some of my R/C models, I could do that.

I may still have a Perry pump hanging around someplace, I'll have to dig it up and give it a try.

Plus, I think Perry is still making pumps, but I'm not sure about that?

I'll work it out.

Thanks again for the reply.

Charles

Mark Scarborough · « **Reply #9 on:** January 12, 2017, 08:27:27 PM »

Options, build a metal tank with the pickup coming out the back corner
build a tank that is wider than long so less distance to affect run

what is your intent, is this a sport model or something you imagine to be competative,, it makes a difference,,
or is it another display model?

Avaiojet · « **Reply #10 on:** January 12, 2017, 08:47:37 PM »

Quote from: Mark Scarborough on January 12, 2017, 08:27:27 PM

Options, build a metal tank with the pickup coming out the back corner
build a tank that is wider than long so less distance to affect run

what is your intent, is this a sport model or something you imagine to be competative,, it makes a difference,,
or is it another display model?

Mark,

Now be nice, my models aren't display, they all will fly.

That sideways tank is a great idea, I'm glad I thought of it.

I'll have to take a good look at the drawings and see if I can apply your idea. A good one actually. See what I can do with it because room is an issue.

The model is designed for competitive stunt, not sport.

Thanks for the reply and the idea. You just may have solved this issue.

Charles

P.S.

OK, now you have me thinking.

I really don't want to make a tank so I'm thinking a clunk tank set sideways.

Then I won't need a pump, less plumbing and less to go wrong. KISS.

Thanks again Mark.

You actually made my evening.

Dan McEntee · « **Reply #11 on:** January 12, 2017, 10:16:01 PM »

Quote from: Avaiojet on January 12, 2017, 08:47:37 PM

Mark,

Now be nice, my models aren't display, they all will fly.

That sideways tank is a great idea, I'm glad I thought of it.

I'll have to take a good look at the drawings and see if I can apply your idea. A good one actually. See what I can do with it because room is an issue.

The model is designed for competitive stunt, not sport.

Thanks for the reply and the idea. You just may have solved this issue.

Charles

P.S.

OK, now you have me thinking.

I really don't want to make a tank so I'm thinking a clunk tank set sideways.

Then I won't need a pump, less plumbing and less to go wrong. KISS.

Thanks again Mark.

You actually made my evening.

Your models are most definitely display models. You have them on display here all the time. Not one has been flown, at all. You keep making excuses such as "braking" in the engines and such. Talk is cheap! You have 12 months worth of flying weather where you live so don't give us the "I don't have time" excuse either! You are just scared to fly them, afraid of possibly damaging one of your hanger queens. At least put up a flight on your Flite Streak. If you prang that you won't be out much. If you would fly your models, then you would be gaining experience that you could put into the models that you are "designing", if you want to call it that, instead of posting "how do I do this" questions. Your biggest problem is that you have too many projects going on at once, and lack the focus needed to finish any of them in a proper manor so that they will perform at some sort of level. You claim that you are "sharing" and "teaching" others but this is exactly how you should NOT go about building models, especially if you think you are going to design a "competitive stunt model." I'm pretty sure you don't know what that is.
And a stunt capable push biplane has been done. I believe none other than Dan Banjock had a stunt capable model of a WW-1 DH-2. Some one correct me if I'm wrong. I think he lost a model in a crash but did fly it in demonstrations at the NATS one year. From the pictures I saw it was pretty scale looking also.
So, I think you should put all these other side projects aside, "brake" in an engine or what ever you need to do, and fly something! Otherwise, I don't think you ever will.
Not bullying, just pointing out the blatantly obvious.
Type at you later,
Dan McEntee

Air Ministry . · « **Reply #12 on:** January 13, 2017, 04:18:00 AM »

TANK ? Ckiken hopper , with the small tank back aft ?

STARTING ? Olde Pommie trick was a tin bottle top ( Fuel Bottle Top ) Fitted behind the prop , as a pulley . For a piece of string . Needs a notch & 3 or 4 turns .

Balance things Nose Heavy and a ten year old can fly em . If you know any ten year olds ? Or Hold on & grit your teeth . Straight Arm , not wrist control .

Mark Scarborough · « **Reply #13 on:** January 13, 2017, 11:54:27 AM »

Quote from: Avaiojet on January 12, 2017, 08:47:37 PM

Mark,

Now be nice, my models aren't display, they all will fly.

at the risk fo piling on Charles,, until they fly, they are in deed, by definition, display models.. and I was nice,, there was no hint of nasty in my post,,

Steve Helmick · « **Reply #14 on:** January 13, 2017, 03:00:36 PM »

Quote from: Lauri Malila on January 10, 2017, 11:53:59 PM

It woulg be interesting to see how it behaves in an aerobatic model. A big part of 4-2-4 run comes from changing tank position (in relation with spraybar). Now, I would think that engine goes rich when you raise models nose. L

If you're doing a pre-launch NV setting drill, yes, it would be "odd", and go richer as the nose is raised. Keeping in mind that the real reason a 4-2-4 "switch" happens is the changing load on the engine, it should be less significant than that. I'm sure Charles won't have a problem with it.

Steve

Avaiojet · « **Reply #15 on:** January 13, 2017, 03:06:34 PM »

Quote from: Steve Helmick on January 13, 2017, 03:00:36 PM

If you're doing a pre-launch NV setting drill, yes, it would be "odd", and go richer as the nose is raised. Keeping in mind that the real reason a 4-2-4 "switch" happens is the changing load on the engine, it should be less significant than that. I'm sure Charles won't have a problem with it. Steve

Steve

Did you see on You Tube the modeler who has an electrical device that makes an electrical motor do a 4-2-4?

Charles

Mark Scarborough · « **Reply #16 on:** January 13, 2017, 03:43:22 PM »

Quote from: Avaiojet on January 13, 2017, 03:06:34 PM

Steve

Did you see on You Tube the modeler who has an electrical device that makes an electrical motor do a 4-2-4?

Charles

Keeping in mind, the 4 2 4 break is pretty much out as far as competative aerobatics is concerned,,

Brett Buck · « **Reply #17 on:** January 13, 2017, 04:21:12 PM »

Quote from: Avaiojet on January 13, 2017, 03:06:34 PM

Did you see on You Tube the modeler who has an electrical device that makes an electrical motor do a 4-2-4?

You mean occasional poster, developer of the feedback motor control system, and World Champion Igor Burger? The one that Igor, Paul , Howard, Orestes, Jim Aron, and many others use? The possibility of which was first suggested in public, as far as I know, in an SSW post about 15 years ago after I had a discussion with Mike Palko at the 2000 or 2001 NATS? Yes, we know about that.

Brett

Akihiro Danjo · « **Reply #18 on:** January 15, 2017, 11:27:21 PM »

This is my fuel tank(s) setup for a pusher canard model that I built 15 or so years ago.
The model is Shinden 15 from a very old kit by KMCo of Japan.

But, there is a big probelm.
I have not flown the model with full (two) tanks yet

I had ever flown it using a rear tank only. So, I haven't prove the fuel system yet

Aki

Avaiojet · « **Reply #19 on:** January 16, 2017, 07:49:35 AM »

Quote from: Akihiro Danjo on January 15, 2017, 11:27:21 PM

This is my fuel tank(s) setup for a pusher canard model that I built 15 or so years ago.
The model is Shinden 15 from a very old kit by KMCo of Japan.

But, there is a big probelm.
I have not flown the model with full (two) tanks yet
I had ever flown it using a rear tank only. So, I haven't prove the fuel system yet

Aki

Aki,

Wow! Great looking model.

Some of the kits, including scale kits that are produced in Japan are outstanding. I had a catalog many years ago but it wasn't printed in English.

The offerings, photos, were very tempting.

I see what you did there and it looks like you extended the shaft? Not sure because I don't know the engine.

I think sideways mounting the tank will work in my case. My tank is hidden inside the fuselage. My model is also a complicated design.

Great that you had plans for the CG.

I'm looking forward to seeing more of your comments and other photos of your models.

Thanks for the reply.

Charles

Akihiro Danjo · « **Reply #20 on:** January 17, 2017, 05:57:02 AM »

Quote from: Avaiojet on January 16, 2017, 07:49:35 AM

Aki,

Wow! Great looking model.

Some of the kits, including scale kits that are produced in Japan are outstanding. I had a catalog many years ago but it wasn't printed in English.

The offerings, photos, were very tempting.

I see what you did there and it looks like you extended the shaft? Not sure because I don't know the engine.

I think sideways mounting the tank will work in my case. My tank is hidden inside the fuselage. My model is also a complicated design.

Great that you had plans for the CG.

I'm looking forward to seeing more of your comments and other photos of your models.

Thanks for the reply.

Charles

Shinden 15 is 50 or so years oldtime kit.
The performance is quite poor because of the weight.
Mine weighs 710 grams though the wing area is only 220 sqinch. Too much wing loading.
It could do only laaaaarge loops and lazy eight.
I moved the engine fwd by using extension shaft. But still needed lots of nose weight to move the C/G.
The C/G on the plan is -20%. At the C/G, my model was still unstable (yeah, it's because this is canard). Now it is -22%.
The engine is OS CV15.
Aki

Chris Wilson · « **Reply #21 on:** January 28, 2017, 07:00:29 PM »

Quote from: Lauri Malila on January 10, 2017, 11:53:59 PM

It woulg be interesting to see how it behaves in an aerobatic model. A big part of 4-2-4 run comes from changing tank position (in relation with spraybar). Now, I would think that engine goes rich when you raise models nose. L

Agreed, so how about we put what we can of the spraybar, like the metering, ahead of the tank by remote installation, perhaps using someone 's cast off LA46 backplate?
That will then only have the low pressure side of the fuel feed in an awkward place and the added benefit of getting the digits right out of that rear prop.

Lauri Malila · « **Reply #22 on:** January 29, 2017, 08:49:27 AM »

I can guarantee that position of needle valve has no effect whatsoever to this hydrostatic pressure at spraybar. It's only about pickup point in tank and the point where fuel mixes with air that matter.
Well, untill tank is empty and there is fuel in fuel line only on engine side of remote valve. It has a small effect to wether engine goes lean or richer before it stops, so you can play a little with height of remote valve.
But as long as system is full of fuel, nothing. L

Chris Wilson · « **Reply #23 on:** January 30, 2017, 02:38:15 AM »

Quote from: Lauri Malila on January 29, 2017, 08:49:27 AM

I can guarantee that position of needle valve has no effect whatsoever to this hydrostatic pressure at spraybar.

With all due respect Lauri, I mildly disagree, the continuity equation is inherently based on a continuous constant flow that has the restriction angled the same way as the flow.

Here the flow is not a constant due to a pulsed demand system and inflight ballistics that definitely change rates.
And I am almost certain that a needle valve has a different internal geometry to that the classic Bernoulli images we are all used to seeing.
I suspect that here a remote needle valve acts more as a system dampener seperating tank ballistics like uniflow and centrifugal force from the chaotic pulsed draw of the inlet.

Lauri Malila · « **Reply #24 on:** January 30, 2017, 11:15:13 AM »

Quote from: Chris Wilson on January 30, 2017, 02:38:15 AM

And I am almost certain..

In that case you should do a practical test.
But I must add that I don't use remote needle for safety reasons but to isolate the valve from direct heat and some vibrations. In any case it's better to have it as close to venturi as possible. L

Dane Martin · « **Reply #25 on:** January 30, 2017, 01:20:34 PM »

If I may add something. Only because Charles is a cool cat...
If I we're tasked with a remote tank and the probability of poor suction, I would run a pressurized tank through a pressure regulator. RC Helicopters are a great example. You could run crankcase pressure through a check valve into the tank. Pretty high pressure there, and then the fuel line to the regulator, then to the engine.
Or! Run a bladder, to a regulator then to the engine. Sure there's no 4-2 break, but a pusher biplane probably don't need all that.

Avaiojet · « **Reply #26 on:** January 30, 2017, 02:20:07 PM »

Quote from: Dane Martin on January 30, 2017, 01:20:34 PM

If I may add something. Only because Charles is a cool cat...
If I we're tasked with a remote tank and the probability of poor suction, I would run a pressurized tank through a pressure regulator. RC Helicopters are a great example. You could run crankcase pressure through a check valve into the tank. Pretty high pressure there, and then the fuel line to the regulator, then to the engine.
Or! Run a bladder, to a regulator then to the engine. Sure there's no 4-2 break, but a pusher biplane probably don't need all that.

"Great" Dane,

Meow, meow.

I think I mentioned I ran Perry pumps and crankcase pumps with my K&B engines.

Mark quickly gave me a method or cure all, that is to mount the tank sideways.

I cannot think of a better way than this. No pumps and a normal draw. Simple install. Should work fine.

Thanks for the reply.

Dane Martin · « **Reply #27 on:** January 30, 2017, 04:01:02 PM »

Quote from: Avaiojet on January 30, 2017, 02:20:07 PM

"Great" Dane,

Meow, meow.

I think I mentioned I ran Perry pumps and crankcase pumps with my K&B engines.

Mark quickly gave me a method or cure all, that is to mount the tank sideways.

I cannot think of a better way than this. No pumps and a normal draw. Simple install. Should work fine.

Thanks for the reply.

10-4. missed that one, but I like the idea of a standard tank. Good luck, that sounds like fun

Avaiojet · « **Reply #28 on:** January 30, 2017, 04:16:49 PM »

Quote from: Dane Martin on January 30, 2017, 04:01:02 PM

10-4. missed that one, but I like the idea of a standard tank. Good luck, that sounds like fun
[/quote

"Great" Dane,

Yes, Mark nailed it.

I bet I still have a few pumps hanging around, probably a Perry and an a K&B 40 back plate pump for anyone interested.

Charles

Chris Wilson · « **Reply #29 on:** January 31, 2017, 01:03:25 AM »

Quote from: Lauri Malila on January 30, 2017, 11:15:13 AM

In any case it's better to have it as close to venturi as possible. L

Why? If as you say, there is no pressure drop anywhere in the system, what does it matter where a valve is located?

Lauri Malila · « **Reply #30 on:** January 31, 2017, 09:53:02 AM »

2 reasons;
-Soft fuel line resonates/pulsates.
-After the tank is empty and only air goes through needle valve, engine goes rich. Normally it cuts better like that but if it's rich for too long, you loose speed.

Igor Burger · « **Reply #31 on:** January 31, 2017, 10:00:23 AM »

Quote from: Lauri Malila on January 31, 2017, 09:53:02 AM

2 reasons;
-Soft fuel line resonates/pulsates.
-After the tank is empty and only air goes through needle valve, engine goes rich. Normally it cuts better like that but if it's rich for too long, you loose speed.

I had it like that

No problems with engine run. Beside fact, that motor stops RICH, not lean : -)))

Lauri Malila · « **Reply #32 on:** January 31, 2017, 10:32:20 AM »

Closer Igor, closer:)

Igor Burger · « **Reply #33 on:** January 31, 2017, 11:07:12 AM »

Well ... it was standard OS max remote NV (it was part of back plate). Beside that stupid burp on end of the tank it worked well, so I did not care :- P

Chris Wilson · « **Reply #34 on:** February 01, 2017, 02:14:17 AM »

Quote from: Lauri Malila on January 31, 2017, 09:53:02 AM

2 reasons;
-Soft fuel line resonates/pulsates.
-After the tank is empty and only air goes through needle valve, engine goes rich. Normally it cuts better like that but if it's rich for too long, you loose speed.

Thanks Lauri, I have learnt something.