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Post  OhBee on Wed Jan 06, 2021 3:52 pm

I've spent as much time as I'm going to using the search function,so here's my question. How big of a fuel tank do I need to run a TD .049 on a controline for 3 min?
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Post  Cribbs74 on Wed Jan 06, 2021 4:20 pm

3/4 to 1oz  is usually what I use and that gives me 5-6 mins. I would try 1/2 oz and go from there. You could always get a 1oz tank and short tank it for the run time you desire.

The tricky part is your engine, prop and environment are all variables that will affect fuel economy so there really isn’t an 100% accurate answer to give.
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Post  OhBee on Wed Jan 06, 2021 4:52 pm

Ya...I don't even know what prop to use!...all I have is a 3/8 oz tank. ... Least I think it is according to the measurements. Seems kinda small for a TD .O49. All I'm familiar with is Babe Bees. ....5cc tanks. They ran long enough to get dizzy!
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Post  Cribbs74 on Wed Jan 06, 2021 6:06 pm

You really can’t go wrong with a 5x3. 6” props load the TD’s too much. However, if you haven’t done it in a while then I would go with a 6x3.

The more you fly the less dizzy you get. You can always do loops and figure 8’s or whatever if you get tired of turning.
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Post  944_Jim on Wed Jan 06, 2021 6:42 pm

OhBee, what have you got for props? I can send up a couple of three-blade 5x3, and maybe a couple of 2-blade 5x3. I don't have a pile of 6" props, or I'd offer them too.

Each time I took a new bird out, I took a few props on either side of "normal." After a few flights, I'd change the prop and try it again...and again...and again. Until I ran out of props to try, or found a personal preference.

If you way over-prop, worst case is a slow-turning, fuel-sucking, stable flight.
If you way short-prop it, worst case is high rpms from the engine with little thrust.

Either way, I recommend short-tanking it and engaging somebody to time your "seconds per turn." Do two or three quickies excluding the first few spins to come up to speed, and then change props and do it again.

There will be a point where you get good traction for stunts, or good speed (and dizzy)...or hopefully something in between in YOUR sweet spot for your type of flying.
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Post  OhBee on Wed Jan 06, 2021 7:22 pm

Deleted....I'll go with Cribbs sugestion...which means I'll need a slightly larger tank.This one looks awfully tiny for a TD .049. My fuel estimates are all based on a babe bee 5cc tank that gives me a 2 min run time. I don't know how much thirstier a TD is!


Last edited by OhBee on Thu Jan 07, 2021 1:22 am; edited 1 time in total
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Post  944_Jim on Wed Jan 06, 2021 7:57 pm

Well, my Scientific P-40 had a 1/2 oz tank feeding the pressure-fed AP .061 for about 2:45 on a 6x3. While it has displacement over the Tee Dee, I bet the Tee Dee would give the AP a good fight.

If you rubber-band the tank to it, you can change on the fly. Considering the impediments you mention, I think you would be best served by that Tee Dee if you de-tune it a bit. Either here, or on StuntHanger someone sleeved the venturi down a bit to soften the engine a bit. Another way to temporarily accomplish this would be to install a Medallion body on that engine.

I would advise use whatever tank is:
On hand no more than 2/3 oz (although I like the 3/8 for you), and
as large as possible without throwing off your CG

And:
Restrict the engine
3-blade 5x3 prop (trade speed for traction)

As long as the tank is rubber mounted and the engine is de-tuned non-destructively, then you can up the game in pieces. Play with props first, then revert to full Tee Dee power.
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Post  OhBee on Thu Jan 07, 2021 12:49 am

How about a screen in the venturi? ... This one is missing
Here's what I have for props...one 3 blade 5×3, couple different 5×3's, 2 blade.. one is square tipped,the others appear to be a cox safety tip type....a 5.5x4.5, a 5 1/4x4, and 6×3.   IF I DO get in the air, there won't be any stunts involved...at least not on purpose. Don't have the reflexes or coordination for that...never did!
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Post  bakergw on Thu Jan 07, 2021 2:02 am

Hi,

I de-tuned my Tee-Dee when running it in for a while by replacing the high compression Tee Dee head with a standard Cox glowhead of one of my surestart engines. If you turn the Venturi and needle around and put one of the round/drum mufflers on it that will also tame the Tee Dee quite a bit, if that is what you are after. Also the glow head adapter that allows the use of standard 1/4 inch glowplugs will detune the engine.

Cheers,
Gary
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Post  944_Jim on Thu Jan 07, 2021 4:26 pm

OhBee, a screen would be a fair thing to try. That may assist with fuel draw at slower speeds. While Tee Dees are neat engines, if the engine will be too much for you, then flying will be a miserable experience.

Gary,
While you did effectively de-tune the engine (which is what OhBee is looking for), the intent of the Medallion body is to increase fuel draw capabilities by restricting the intake. A smaller cross-section throttle port will induce more vacuum signal to the spray bar/NVA. Of course, the smaller intake also throttles the engine down a smidge.

The best part is the better vacuum signal reduces the need for pressurized fuel supply, whether by choking the engine with a screen, or installing the Medallion front end.

I will admit that I don't have a Tee Dee, have never had a Tee Dee, and am making my recommendations based on anecdotal stories of Tee Dees needing pressure.

I think Ron Cribbs or Ken Cook mentioned before that Tee Dees don't need pressure (either here or on StuntHanger). Regardless, I do believe a stock Tee Dee is the wrong engine for the purpose, given OhBee's desires to do only Roundie-Roundie.

OhBee, if I had a spare Medallion, I'd offer to swap at my expense. Alas, I have only two...for a future twin.



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Post  OhBee on Thu Jan 07, 2021 5:13 pm

I don't care if its detuned or not...and this is a hot modified version.....the question was what size tank to run,as I know they are thirstier than a Babe bee.....which is all I have to compare with. Couple more coats of clear and it will need all that power to get airborn! 😱
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Post  dckrsn on Thu Jan 07, 2021 6:04 pm

Hi O.B. Since you're talking about a modified
TeeDee, your safest bet might be to put
her on a test stand, time her and watch
the fuel consumption. For the small wonders
that they are, little tweaks(and there are
dozens of them) can have a big effect,
especially on fuel consumption. Keep us
posted, I'd be interested on the engine's
mods and how they affect her thirst.
Bob
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Post  944_Jim on Thu Jan 07, 2021 7:34 pm

Well OhBee,

Then I loosely suggest the biggest tank you can reasonably fit on it. A 1/2 or 2/3 oz tank can always be short-filled as long as you fill at least to the point the fuel feed tube is in fuel while you start her up. I certainly wouldn't go much bigger than that, and really believe a 3/8 tank will get you in the air long enough to wish things would be a bit more sedate...at least until you discover your flying legs again.
Once the plane is flying, the rest of the fuel of a "short-tank" will sling outboard to the tip of the wedge anyway. I still like the idea of interchangable rubberbanded tanks. You'll get to play with CG and times by changing tanks.

I fill my tanks with a 5 cc syringe. The Scientific P-40 needed at least two syringes to ensure fuel draw while on the landing gear (for starting), unless I turned the outboard side down. Then no matter how short a fuel load, it still got picked up. The bonus to short runs is that you have just enough time to think of what to change next without wishing for an excuse to land. You wind up with more, but shorter test flights per outing until you build up to longer flying times with a more sorted-out plane.

I'm dying to see this one completed. The colors are wonderful, and the work is fabulous! I hope to see video.


Last edited by 944_Jim on Thu Jan 07, 2021 7:38 pm; edited 1 time in total (Reason for editing : Some tweeks in the message)
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Post  944_Jim on Thu Jan 07, 2021 7:43 pm

OhBee, I may have a spare tank or two laying around...post the measurements of yours so we know what you have. I'll check to see if I have moderate steps up from there.
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Post  OhBee on Thu Jan 07, 2021 11:24 pm

This is the only tank I have.....looks tiny!   It is 35mm long, 23 mm wide from wedge to flat side,and 24 mm thick at flat fill/vent side.  From what I compared it to on web sites it should be a 3/8oz tank.... but it looks smaller than that to me.TD .049 run time 20210112
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Post  944_Jim on Fri Jan 08, 2021 11:18 pm

I'll check my stock in the am.
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