175 wing vs long range tanks STC.

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175 wing vs long range tanks STC.

Postby motoadve » Thu Dec 03, 2020 11:18 pm

Is the long range tank the same as the fuel tank on the 175?
I read the 175 has 9 gallons, unusable fuel, is the long range STC the same shape tank, and 9 gallons unusable?

Going to see a plane tomorrow I might buy with long range fuel tanks, I assume are Del Air.
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Re: 175 wing vs long range tanks STC.

Postby GAHorn » Thu Dec 03, 2020 11:47 pm

You’ll have to supply more info than that...or ask the seller what they mean by “long range tanks”.

There are several methods to add fuel capacity to a 170: Javelin tank on the floor of the bag compartment, 175 wing tanks, or Flint tip tanks, and maybe others.

I’ll add a cautionary note: It sounds as if an eager buyer might be charging into a prospective purchase fairly uninformed about the airplane being offered. This can be a very expensive way to seek an airplane to buy. Getting a “specification” sheet, photos, and doing an online search of FAA database might be a better way to start out. Most aircraft maintenance records of modifications can be obtained online with or without the seller’s permission. :wink:
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Re: 175 wing vs long range tanks STC.

Postby motoadve » Fri Dec 04, 2020 12:13 am

Its a modification to the wings, this is why I thought they could be Del Air when I talk to the owner tomorrow I will ask more info about which kind of STC is this one.
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Re: 175 wing vs long range tanks STC.

Postby DaveF » Fri Dec 04, 2020 9:38 pm

If it’s Del -Air, find out all you can and let us know. Which mod, the 15 or 30 gallon? Who did the work? How long did it take?

I’d love to have a Del-Air fuel tank mod in my airplane.
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Re: 175 wing vs long range tanks STC.

Postby motoadve » Sat Dec 05, 2020 3:17 am

It is Del Air, 56 gallon total , has two fuel filler caps per side, if you want to fill the tank at full cspacity you need to use the outboard one.
Will meet the mechanic who made the install tomorrow.
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Re: 175 wing vs long range tanks STC.

Postby c170b53 » Sat Dec 05, 2020 3:47 am

After a fill-up, I guess you can’t turn for a bit without spilling some gas with the Delair ?
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Re: 175 wing vs long range tanks STC.

Postby motoadve » Sat Dec 05, 2020 12:12 pm

So now that is confirmed its Del Air , can anyone confirm , how much is unusable fuel?

Why will the fuel spill after full fuel and turning?
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Re: 175 wing vs long range tanks STC.

Postby c170b53 » Sat Dec 05, 2020 6:23 pm

Well I’m not sure why you would need another filler neck but if the tank was jammed to the top as I imagine it would be with that approach then fuel would likely flow out of the fuel vent with any manoeuvre other that level flight. I’ve got standard 175 tanks and I have to be cognizant not to do the same for the same reason.
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Re: 175 wing vs long range tanks STC.

Postby bat443 » Sat Dec 05, 2020 7:42 pm

Not if in positive G coordinated flight. Watch the Bob Hover video of him rolling the Aero Comander with the filled glass setting on the top of the panel.

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Re: 175 wing vs long range tanks STC.

Postby n2582d » Sat Dec 05, 2020 9:42 pm

motoadve wrote:It is Del Air, 56 gallon total , has two fuel filler caps per side, if you want to fill the tank at full cspacity you need to use the outboard one.
...

In the series of four YouTube videos showing the installation of the 30 gallon Del Air long range tanks the installer capped the inboard filler necks as seen here.
Screen Shot 2020-12-05 at 1.15.38 PM.png
I've previously written -- but can't find my source now -- that the unusable fuel on the Del-Air conversion is the same as the original C-170B tanks -- 5 gal./30 lbs. Del-Air's fuel neck design eliminates the potential for water intrusion that plagues the original Cessna design.
Screen Shot 2020-12-05 at 1.22.33 PM.png
Screen Shot 2020-12-05 at 1.22.33 PM.png (120.9 KiB) Viewed 469 times
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Re: 175 wing vs long range tanks STC.

Postby johneeb » Sat Dec 05, 2020 10:50 pm

Here is a copy of the Flight Manual supplement for Del-Air long-range tanks. This modification adds 7 gallons to each tank, the tanks look like Gary's photo just that the added tankage is smaller. As you can see from the supplement the total fuel is 56 gallons (28 each tank), the total unusable is 5 gallons giving 51 gallons usable. If I recall properly Harry's logic to adding the filler at the outside end of the tanks was that is allowed the tanks to have higher usable fuel (probably less of an issue for the A models then the Bs with their wind dihedral).
Del-Air also offers a larger modification I think 60 gallons total.

Del-Air-long-range-Fuel-Tank-modification-Airplane-Flight-Manua0001 - Copy.jpg

Del-Air long range Fuel Tank modification Airplane Flight Manua0002.jpg
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Re: 175 wing vs long range tanks STC.

Postby GAHorn » Sat Dec 05, 2020 11:01 pm

I kinda get worried about structural strength loss when so many ribs are replaced with fuel tanks... maybe it’s unfounded but I just can’t see why hollow tanks can be equal to the torsional strength of the ribs which are replaced.
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Re: 175 wing vs long range tanks STC.

Postby IA DPE » Sun Dec 06, 2020 12:02 am

Normal capacity of my bladder is two hrs, three if using Long Range, so the stock tanks are fine for my mission. :roll:
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Re: 175 wing vs long range tanks STC.

Postby n2582d » Sun Dec 06, 2020 12:13 am

Screen Shot 2020-12-05 at 4.11.29 PM.png
Personal range extender :lol:
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Re: 175 wing vs long range tanks STC.

Postby motoadve » Sun Dec 06, 2020 12:20 am

Thanks for all the info.
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