Tip Tank Usage

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SJDobby
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Tip Tank Usage

Post by SJDobby »

Hi

Is there a recommended "best practice" for the Bonanza tip-tank usage? Specifically:

1. Is it advantageous to carry fuel in the tips "generally" (even when you haven't filled the main tanks) to give the wings a little more structural resistance to bending forces (such as what you might get flying through cloud)?
(I'm no engineer, so please do correct me if the above theory is incorrect or in fact if the reverse is true!)

2. At what point in a flight should you be pumping tip-fuel into the main tanks? I generally only wait until the main tanks are down to about 90% full, but in light of the possible reply to the above question maybe it is better to use the tip tanks as the "reserve" tanks, i.e. keep them full for as long as is practicable and only empty them into the mains once the mains get down, say, below a third or so full?

Thanks
Simon
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AKar
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Re: Tip Tank Usage

Post by AKar »

1. I'd say no. Practical issues dictate that often you need to meet takeoff or landing limitations with any imbalance in the tip tanks. You'd need to worry on balancing the fuel quantities in the tips more than in the mains to stay within the book. Hence, you'd probably want have the tips at or below about 1/4 "as soon as practicable" to remain comfortably within the book, and forget about any possible imbalance procedures should the need rise.

Structurally, the question is complicated. While the tips reduce steady state bending loads, they potentially do add some harmonic 'pendulum loads' (that basically cause more fatigue) in flight through any turbulence. Note that the airplane is fairly well-stressed on its own, so there is little need to relieve any regular wing loadings.

2. One STC provider tells you to "initiate transfer with both main tanks at least 1/2 full" as the "fuel consumption may exceed tip tank transfer rate."

My personal thinking considers these tip tanks as an amendment to the existing airplane configuration. I would use them as needed, for cruise range extension as necessary. I would only carry in them what extra I needed and would deplete them as soon as practicable (maybe leaving just a few gallons to the bottom).

But this is purely on the paper, and I don't recall having really worked on any actual tip tank modification. So I'd welcome any other opinions!

-Esa

Les Parson
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Re: Tip Tank Usage

Post by Les Parson »

I've been looking for expert advice on this topic for some time. As a member of ABS (American Bonanza Society), there are quite a few pro tip tank posts but I don't recall any specific to best tip tank practices/procedures. I think I might enquire and will report back.

SJDobby
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Re: Tip Tank Usage

Post by SJDobby »

Thanks Esa. I think I shall amend my own practice and only carry fuel in them when absolutely necessary and start draining them as part of my “cruise climb” workflow.
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AKar
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Re: Tip Tank Usage

Post by AKar »

SJDobby wrote: 22 Feb 2020, 11:59 Thanks Esa. I think I shall amend my own practice and only carry fuel in them when absolutely necessary and start draining them as part of my “cruise climb” workflow.
I think I should add that I don't consider it a bad practice at all to carry fuel in the tips, it is just the pragmatic side in me that quickly finds no significant benefits in doing so, unless necessary for the total fuel amount.

Should a tip become unusable (for any reason), the imbalance issue is indeed there. Apparently, though, at least D'Shannon's STC finds any related handling issues rather modest, simply limiting you to flaps up landing should a difference of more than 1/2 tank exist. Also, the tips rely on electric transfer pumps. In an unlikely event of failure of one (or of the electrical system of the aircraft), you can end up with some significant amount of unusable fuel. Hence, I'd prefer transferring the required fuel into the mains as soon as practicable.

Overall, I think tip tanks are rather great add-on to an airplane. They can significantly increase the total fuel load with little or no penalties whatsoever, or even with some credit should the aircraft otherwise be fuel weight limited.

-Esa

Les Parson
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Re: Tip Tank Usage

Post by Les Parson »

Here is some useful info re V35 Tip Tank ops:

My question:

Are there any publicly available procedures and/or articles on best practices for V35B Tip Tank operations?

Response:

Les,
Tip tanks are lovely items, as you know. Plus they, in my opinion, make the Bonanza look better. But on to your answer.
In my opinion, the key to proper flight planning in an single engine airplane is to have most of your usable fuel in one tank while you are landing. In a V35B with tip tanks, you may have 104 to 114 gallon of usable fuel on board at time of departure.
I fly lean of peak. So, my flight plan is 155 knots at 11.5 GPH. (I have the IO550B). This power setting is 2300 RPM at 11.5 GPH. I lean to about 10 GPH and then increased the fuel flow until I am about 11.0. I then increase the fuel flow until I am about 1400 dF on my highest running EGT. After this, the only time I make adjustments is if there is a major Baro change.
After this, how things work depends upon how quickly your fuel is transferred from the tip to a main. In your plane empty the left main. I would then fill the left main from the left tip. I would do this by connecting external power and run the left tip pump for about 40 minutes and see how much has been transferred.
I would do the same on the right side. After you know how long it takes to transfer your tip fuel to your main, then you know how long you can operate your pumps. I would avoid prolonged operation of the tip tank pump without any fuel.
So, if it take 45 minutes to transfer the fuel from each of your tip tanks, you then have a great idea how to plan your fuel use.
If you do not have a digital fuel flow device such as the Shadin fuel flow device (the JPI, EI, Insight, Garmin and Dynon systems have very accurate fuel flow devices), I would install one. What an improvement in fuel planning.
I do not leave my tip tanks empty. When I have run my tips dry, I add about 1/2 gallon of Marvels Mystery Oil to each tip and then run the pumps until you hear a change in the pump sound. Then you have primed your fuel line. More importantly, you have now eliminated moisture contamination of your fuel lines from the tip and prevent your pumps from being contaminated by rust, etc. I have not had to change a fuel pump in over 5 years after I began doing this. Note my airplane is in its hanger most of the time.
Now that you know how long it takes to transfer your fuel, you can plan to land with your left main at with at least 20 gallons of fuel on board.
ON the other hand, consider this. If you have 114 gallons of usable fuel on board, that means that you have about 9.8 hour of usable fuel (at 11.5 GPH). I have about 8.4 hours of fuel because my plane holds 97 usable fuel (different fuel cell set up). So I rarely fly longer than 6.5 hour legs. For example, I am planning a flight next week from Wisconsin to San Diego area. I will fly to Borger Texas. Refuel and then fly on to Palomar. Total time will be about 11 hours. The Bonanza's have fantastic seats. I do not get the sore butt syndrome I would get in a Piper or a Cessna.
Oh, I do have a relief tube. And I carry depends (for my other passengers).

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Neon
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Re: Tip Tank Usage

Post by Neon »

When I was flying, it was recommended with multiple tanks, to empty the inner tanks before the outer ones. The reason
was it increases the roll stability of the plane rather than the other way around due to more mass on the outside of the wing.

The physics of that seems sound, whether it's stiill that way I don't know.

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AKar
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Re: Tip Tank Usage

Post by AKar »

Neon wrote: 07 Mar 2020, 06:15 When I was flying, it was recommended with multiple tanks, to empty the inner tanks before the outer ones. The reason
was it increases the roll stability of the plane rather than the other way around due to more mass on the outside of the wing.

The physics of that seems sound, whether it's stiill that way I don't know.
Interesting, in what aircraft was that? Bonanza?

I am not sure how much it matters in practice if speaking solely of outer wing tanks and tip tanks, but generally speaking the added weight 'outside' (adding the moment of inertia around the vertical axis of the airplane) tends to worsen the spin characteristics, in some cases significantly so.

-Esa

skyhawkii
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Re: Tip Tank Usage

Post by skyhawkii »

1. I think dicussing this gets a little bit complicated. On the one hand positive wing load is reduced in flight with full tips. On the other hand there is more negative wing load at touchdowns. I believe negative wing load adds more stress to the wings because the wings are designed for positive load. This is why most planes can handle more positive g's than negative ones ( aerobatic planes too).In case of the Bonanza it's reduced from utility to normal category when you install tip tanks. However it's not really a drawback, because most planes in this class are normal category airplanes. I would only fill them up when needed and some time a little bit for checking the transfer pumps.

2. I would practise it exactly like it's recommended by D'Shannon. I wouldn't think too complicated. On a long trip I would transfer the fuel to the mains asap, because the fuel is only accessable for the engine when it's in the mains. I would run the mains half down and then transfer all fuel from the tips to the mains. If anything's gonna happen at this time or later (transfer pumps fail, or loss of electrical power which is needed for the pumps), I got half mains which give me enough time to look for an airport for landing.

Michael

Les Parson
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Re: Tip Tank Usage

Post by Les Parson »

skyhawkii wrote: 07 Mar 2020, 16:51 1. I think dicussing this gets a little bit complicated. On the one hand positive wing load is reduced in flight with full tips. On the other hand there is more negative wing load at touchdowns. I believe negative wing load adds more stress to the wings because the wings are designed for positive load. This is why most planes can handle more positive g's than negative ones ( aerobatic planes too).In case of the Bonanza it's reduced from utility to normal category when you install tip tanks. However it's not really a drawback, because most planes in this class are normal category airplanes. I would only fill them up when needed and some time a little bit for checking the transfer pumps.

2. I would practise it exactly like it's recommended by D'Shannon. I wouldn't think too complicated. On a long trip I would transfer the fuel to the mains asap, because the fuel is only accessable for the engine when it's in the mains. I would run the mains half down and then transfer all fuel from the tips to the mains. If anything's gonna happen at this time or later (transfer pumps fail, or loss of electrical power which is needed for the pumps), I got half mains which give me enough time to look for an airport for landing.

Michael
Thanks for the info. What I have been trying to confirm for quite awhile is if the A2A V35 Tips are D'Shannon or Osborne. Can you confirm?

skyhawkii
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Re: Tip Tank Usage

Post by skyhawkii »

I'm pretty sure it's D'Shannon. The Osbourne's look a little bit different. But there should be no big difference in general handling, when both have the transfer pump system.

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Neon
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Re: Tip Tank Usage

Post by Neon »

The way I do it is: Run on the left tank till I use 1/4, switch to the right, and drain the left tip tank
into the left main tank. Reverse this on the next fuel switch. It doesn't take long to empty
the tip tanks.

As to the effects on spin characteristics, if that is true, then I think that would be a greater concern
than roll stability.

Les Parson
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Re: Tip Tank Usage

Post by Les Parson »

Neon wrote: 08 Mar 2020, 01:02 The way I do it is: Run on the left tank till I use 1/4, switch to the right, and drain the left tip tank
into the left main tank. Reverse this on the next fuel switch. It doesn't take long to empty
the tip tanks.

As to the effects on spin characteristics, if that is true, then I think that would be a greater concern
than roll stability.
Good points.

awash2002
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Re: Tip Tank Usage

Post by awash2002 »

Les what altitude are your flying at right now I'm at 11,000 and 11.4gph with the IO-550 I also want to try it with the stock IO-520
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