Intravenous bag as fuel tank, why is it forbidden?
10-13-2014, 12:01 PM
#28
I do understand having a bladder inside of a ridged tank of some sort. But, is it truly worth all of the effort? I do know that Kevlar tanks will tear apart in the air, after my F-18 exploded in the air that started as flutter on the stab. In truth, due to the AMA saying NO bladders, no matter how it is contained. As a Turbine CD who signs guys off, and teaches jets, I wouldn't fly a jet with a bladder, nor sign a guy off with a jet with a bladder. I actually have issues with guys using DuBrow tanks for fuel too. I have seen a lot of those tanks, and truly don't consider them safe. Just isn't worth risking my CD, Waiver, or the liability if something happens and the jet wrecks causing damage and fire to others' property.
Last edited by RCFlyerDan; 10-13-2014 at 01:28 PM.
10-14-2014, 04:17 AM
#29
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Wow... I lost track of the thread during the weekend! The initial objective of the question was not to go over the rules. But to understand why it is like this.
Lance: You had a great point, having a startup tank become hard or even impossible.
One advantage would be to be able to 2 tanks without worrying about one being empty before the other one and draining air in the system (so being able to have 2 tanks in parallel, not in series).
BTW: We have the same rule here in Canada.
Lance: You had a great point, having a startup tank become hard or even impossible.
One advantage would be to be able to 2 tanks without worrying about one being empty before the other one and draining air in the system (so being able to have 2 tanks in parallel, not in series).
BTW: We have the same rule here in Canada.
10-14-2014, 02:04 PM
#30
RCFlyerDan,
I would respectfully disagree with you on the DuBro or Sullivan tanks. My experience is that they are quite strong and have held up well in crashes... better than the fiberglass and kevlar tanks which usually break apart at the seams. I've had the stoppers come out in crashes, but that happens as well with the fg/kevlar tanks. Unfortunately, they aren't available in the many shapes and sizes that fit our models, and the cost to the kit mfgs to produce the blow-mold plastic tanks in the myriad number of configurations is cost prohibitive. Making a mold to produce a fg/kevlar tanks is relatively inexpensize, so that's why we have them.
KennyMac
I would respectfully disagree with you on the DuBro or Sullivan tanks. My experience is that they are quite strong and have held up well in crashes... better than the fiberglass and kevlar tanks which usually break apart at the seams. I've had the stoppers come out in crashes, but that happens as well with the fg/kevlar tanks. Unfortunately, they aren't available in the many shapes and sizes that fit our models, and the cost to the kit mfgs to produce the blow-mold plastic tanks in the myriad number of configurations is cost prohibitive. Making a mold to produce a fg/kevlar tanks is relatively inexpensize, so that's why we have them.
KennyMac
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Marvinf14 (12-20-2022)
10-14-2014, 02:20 PM
#31
KennyMac! Thank you! And I respect your views too. You made me think more about wrecks with 50cc+ size gas models, since I have seen or experienced more of those kind of wrecks. The larger the plane, the better protected the tank is inside and usually doesn't move much off of the wing tube, and stays in tact. 50cc and smaller, normally will get some damage. And you are right, worse is the tank punctures and yes the stopper comes out. So, I concede to the Dubro and Sullivan styles of tanks. Thank you for a polite conversation on the subject.
10-14-2014, 02:20 PM
#32
I would respectfully disagree with you on the DuBro or Sullivan tanks
I have seen a couple of crashes with dubro equipped jets where the fuse was destroyed and the tanks still held some fuel. Tanks were damaged, some had holes in them...but none were split open. Every crash I have seen with fiberglass or Kevlar tanks ended with the tanks split wide open.
10-15-2014, 04:34 AM
#37
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Because the bag in the main tank(s) will not allow any suction for pumping the fuel from the extra outside tank (And I seriously doubt that the gravity will do the job). Not to say that the diaphragme will act a barrier for the fuel...
10-15-2014, 05:08 AM
#38
A key to plasma bag working is that there is ZERO air in it, and it stay that way. So if it's 100% fuel, and slowly collapses as you draw it down, there is no clunk required.
I used a pair of them initially on my ducted fan Yellow Aircraft SR-71 years ago. I used them for the first 3 flights, and curled them around the ducting right around the engine area.
The issue I ran into, was that something in the glow fuel, was slowly hardening up the pliable, soft material in them, which caused me to have a hard time ever getting the mixture correct.
After 3 out of 3 engine failures on an engine during the first 3 flights, I switched to a home made torpedo shaped tank mounted in the ducting right behind the engines, out of 2, 10 ounce round tanks plumbed in series. It cut down the thrust, but finally got the engines to run reliably, and I went on to fly it for 3 years without suffering another engine failure, before retiring the plane.
Another point was that when fueling you had to be careful, since there was no outlet or 'vent' in them, if you over filled them you could crack or break whatever was around them. They could continue to swell and make for a very effective hydraulic jack to break whatever they were around, when fueling.
Lance
I used a pair of them initially on my ducted fan Yellow Aircraft SR-71 years ago. I used them for the first 3 flights, and curled them around the ducting right around the engine area.
The issue I ran into, was that something in the glow fuel, was slowly hardening up the pliable, soft material in them, which caused me to have a hard time ever getting the mixture correct.
After 3 out of 3 engine failures on an engine during the first 3 flights, I switched to a home made torpedo shaped tank mounted in the ducting right behind the engines, out of 2, 10 ounce round tanks plumbed in series. It cut down the thrust, but finally got the engines to run reliably, and I went on to fly it for 3 years without suffering another engine failure, before retiring the plane.
Another point was that when fueling you had to be careful, since there was no outlet or 'vent' in them, if you over filled them you could crack or break whatever was around them. They could continue to swell and make for a very effective hydraulic jack to break whatever they were around, when fueling.
Lance
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Marvinf14 (12-20-2022)
