175 wing vs long range tanks STC.

[motoadve]

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.

[GAHorn]

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.

[motoadve]

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.

[DaveF]

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.

[motoadve]

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.

[c170b53]

After a fill-up, I guess you can’t turn for a bit without spilling some gas with the Delair ?

[motoadve]

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?

[c170b53]

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.

[bat443]

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.

Tim

[n2582d]

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

Note that this YouTube video incorrectly shows reinforcement rivet holes between the nut plates on the top forward spar going through the leading edge skin. The additional rivets should not fasten the leading edge skin. As you can see at the end of his fourth video, with the leading edge skin riveted to the front spar, the fuel tank cover cannot tuck under the leading edge skin like it is originally designed to do.

[johneeb]

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

[GAHorn]

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.

[IA DPE]

Normal capacity of my bladder is two hrs, three if using Long Range, so the stock tanks are fine for my mission.

[n2582d]

Screen Shot 2020-12-05 at 4.11.29 PM.png

Personal range extender

[motoadve]

Thanks for all the info.