Tip Tanks

Webb · #1 05-25-2009, 08:00 AM

As much discussion as I have read on more fuel, I'm surprised that we don't see tip tanks like you see on certified aircraft. That dawned on me when watching the Aermacchi on our favor spy, 007 last night.

http://www.airpowerinternational.com/marchetti

Personally, I think it's a sexy look but at what cost.

The guy in the hanger next to me has a BE35 with factory tanks that allows 200 lbs more gross. Each of his hold 20 gallons.

I was thinking 10 gallon tanks (20 total) would be just about the right size for an RV. Gee - Think of it as another pro-seal project.

All you engineering guys out there, is this folly or a good ideal?

Bob Axsom · #2 05-25-2009, 08:30 AM

I have tip tanks that extend the wing span by 18 inches (17 gallons total added fuel). I remove them and the stock tips for racing. I just reinstalled them for out trip to California Thursday when we get back I have to switch back to racing configuration for the Tennessee Valley event at Courtland, AL (www.sportairrace.org). At the end of July I will be flying without them in the AirVenture Cup race from Dayton to Oshkosh and I am sweating the fuel exhaustion threat at high burn rate and prevailing head winds. Based on my experience I would add fuel capacity within the existing envelope some way. the fuel management system is another concern that you have to deal with. All four of my tanks are individually selectable with no pumps other than the engine driven pump and the standard aux pump. There is also an all fuel off position of the main fuel valve.

Bob Axsom

frankh · #3 05-25-2009, 09:02 AM

of Van's wing tips do add speed in the form of less drag..I bet the tanks would cost you that advantage..whatever it is.

Frank

rvbuilder2002 · #4 05-25-2009, 10:05 AM

Quote:

Originally Posted by frankh

of Van's wing tips do add speed in the form of less drag..I bet the tanks would cost you that advantage..whatever it is.

Frank

Test comparisons have showed no measurable speed difference between the old style (horner) and the new style (sheared) tips, which is the reason Van's has never promoted them as providing any speed increase.

Bob Axsom · #5 05-25-2009, 10:55 AM

Farn Reed's tip tanks as I was installing them during the build - stock tips go on the end:

Home made racing tips (slicker than GOS):

Bob Axsom

miyu1975 · #6 05-25-2009, 12:01 PM

Very nice tip tanks..and racing tips. I wonder how difficult it would be to make'em.??

Bob Axsom · #7 05-25-2009, 12:23 PM

The tanks are a beautiful piece of work - I'm sure it would take a lot of thought careful design and quality work. Their performance has been flawless and they give me another 1.6 hours at WOT and 2450 rpm.

The tips required making two molds and a aluminum stiffner/closure in the area of the aileron.

Bob Axsom

frankh · #8 05-25-2009, 12:55 PM

Your tip tanks create..They certainly have the nice advantage of being built seperate to the (flying) airplane and can be installed without too much effort.

Frank

az_gila · #9 05-25-2009, 03:58 PM

Quote:

Originally Posted by Bob Axsom

Farn Reed's tip tanks as I was installing them during the build - stock tips go on the end:

...

Home made racing tips (slicker than GOS):

...

Bob Axsom

...are those long through bolts that attach to fittings on the main spar and rear spar to take the extra loads?

I presume there are internnal baffles as well.

Bob Axsom · #10 05-25-2009, 04:31 PM

Quote:

Originally Posted by frankh

Your tip tanks create..They certainly have the nice advantage of being built seperate to the (flying) airplane and can be installed without too much effort.

Frank

When I remove the tip tanks and stock tips and install the racing tips the speed increase in speed at 6,000 ft density altitude (WOT, 2720 RPM, 3 way, NTPS spreadsheet) is 3 kts TAS.

Bob Axsom