Aux Tanks

[flightexpress]

I was thinking about getting Aux tanks for my air command..But I'm not sure if I want them..Just looking for some fedback, on what people think of. Is there any alternatives..Would like pics if you have them on your machine...

Kurt

[StanFoster]

Kurt: I had them on my Air Command and really liked them. They held 7 gallons but 6 was usable. On a cross country I would just burn off my side tanks for one hour...then switch to my 7 gallon seat tank. You could run the side tanks completely out if you switched to the seat tank right away. The engine would start loosing rpm's giving you plenty of warning.

Stan

[CLS447]

I think that they are fantastic tanks! I would pipe them up a little differently than the original instructions show, though!

[GyroRon]

My thoughts.... Adding the Aux tanks and filling them up with gas adds another 45-50 pounds of weight below the thrustline. If the gyro already has the low riding arrangement and HTL I wouldn't consider it at all. It makes a bad thing worse. If it were CLT I would consider it, but only if I needed the extra gas and couldn't make stops along the way.

[StanFoster]

Kurt: I found this picture of my Air Command. I had over 120 hours with those side tanks ..flew in all kinds of wind...all kinds of cross countries...and I would not fly without those tanks. It handled like a dream.


Stan

[GyroRon]

Okay, put them on, add 100 pounds of lead weight to the bottom of the keel, raise the engine and prop up 10 more inches and to hell with the science, It will fly like a dream and you will never have a problem.

[flightexpress]

Thanks Ron, Chris and Stan..I really like all your post..Stan thanks for the photo..I think I will get them........Kurt

[CLS447]

Ron, who pissed in your Cheerios this morning? LOL

[StanFoster]

Kurt: Here is another view with Gyro Jenny onboard.

Chris: Looking forward to chatting with you at Bensen days.

Stan

[StanFoster]

Steve: They came with my Air Command. They are just the standard side tanks they sell.

From lots of experience in that machine.......it flew very nice.

[StanFoster]

Kurt: I have respectfully taken Udi's advice and decided to delete my comment made in haste.

CLT is the best setup.


Stan

[StanFoster]

Steve: I miss that little machine. But I used it as a stepping stone to my RAF.

Stan

[GyroRon]

Ron, who pissed in your Cheerios this morning? LOL

Nobody did... I just get frustrated when newbies get advise that throws everything we have learned about the importance of thrustlines out the window.

It is not a matter of will it fly good or not. It is a matter of will it bunt over or not, and if it is a HTL gyro, it can bunt over. Adding extra weight, especially another 40-50 pounds worth that low in comparison to the thrustline just makes the gyro more easily able to bunt over, because what it does in effect is lowers the gyros vertical center of gravity in relation to the prop thrustline.

Reguardless of the science behind all this, will it be cool to have the extra gas? YES.... Will it still fly good? YES..... Will it still be able to be flown in winds? YES.... So what Stan is saying is absolutely true.

[RICK MARTIN]

Damn! This is some great entertainment!!

[GyroRon]

If you want to have more gas to be able to fly far far away, here is a better way to do it. It would Help Raise the Vertical CG UP making a HTL gyro less of a HTL gyro.

Look at the Silver aluminum tank that wraps around the mast here in this pic. I also flew this gyro is winds and on cross countries and it also handled like a dream! Plus it was CLT and I did not have to worry about PPO being a threat. :)

[Udi]

Good grief... The only fact Ron forgot to mention is that, historically, a high thrust line gyro is particularly lethal in the hands of a high time fixed wing ATP. Stan - I like you and I wish you were a bit more careful giving advice. This kind of wording "Kurt: I assure you that you will do just fine with those tanks. Just have a good stab set with some negative incidence...and you good to go." may come back to haunt you one day. I know you feel completely comfortable with anything that you fly but history tells another story. If someone does what you said because "you assured him" and then something happens to him you will have it on your conscience. All you can assure him is that YOU did not have a problem.

Just a little bit more entertainment for Rick...

Udi

[mcbirdman]

Dang - Ron you are getting good at ferreting out those comments.......

And good at getting right back to the point of what matters more - but is often lost in what we don't want to have to worry or talk about..... and then your second post, a little more shorter for not getting the point...... hmmm who's posting style does that remind me of ? quality, short, informative, confident, commanding and a little strong if you were missing the point..... :D

[StanFoster]

Udi: You are correct. That statement I made in haste..."I assure you you will do fine....." should not have been said. I went back and deleted that and left a side note. :)

Your critisism is palatable and I respect all your posts. Very interesting and deep stuff you put out. Thanks.


Stan

[flightexpress]

Thanks for every one's info..I plan on getting them today from air command..
Kurt

[MMorgan]

I had bought a set of tanks last year for my aircommand but never put them on for the reasons stated by Ron. Doug Riley also had the same opinion when I asked him about it at BD last year.

Mine also flew very well but you can't argue with known physics or science. You will be lowering the vertical CG.

[Dean_Dolph]

Two obvious questions pop up! Do they have to be mounted low? Is there any higher place to mount them? I haven't studied the problem or given it any thought but thought I would ask any how!

[scottessex]

What about a CLT aircommand conversion? are they OK on that?

My old KB3 had the boat tank mounted on the side, low next to the keel, Although it seemed to me to handle just fine, The new soma, although not CLT, has a seat tank, and the seat is higher, and has a larger horiz stab. There is no comparison to how much better the soma flys, It just fly's nice, nice and easy, It will still pitch up in gusts, but nothing like the KB. Could it be just the fact that the fuel weight is up higher? I have some A/C aux tanks also, But I have not installed them because I don't want to screw it up. whether it would or not, I don't know.

[GyroRon]

If you mount thost tanks where they are intended to be mounted, on any gyro, you are going to lower the vertical CG period. If your gyro is CLT it will no longer be CLT with these tanks filled up with gas. If your gyro is HTL and you got these tanks on it filled up with gas you may have just went from a 6 inch thrust offset to a 8 or 9 inch offset.

Again, like I said in my smart assed post - the 2nd one in this thread - you could bolt 100 pounds of lead to the bottom of the keel and raise the thrustline intentionally up another 10 inches. The gyro will still fly. The rotor on a gyro will make up for a extremely poorly laid out airframe.

But if you read what Scott just posted, and the many other comments others that have gone from very HTL to CLT or near CLT, There is a appreciable difference that can be felt, and it is instantly felt as a very good difference.

The physics and science tells us that a CLT gyro will not be able to do a power push over and one like the Aircommand in the pic Stan posted can do a power push over.

The accident reports that show so many fatal accidents are almost all HTL machines and in so many cases the accident can be traced to a Bunt over due to the thrust offset. It is HTL aircommands, HTL RAF 2000's, HTL Bensens and modified Bensens, etc.... that these accidents have taken place in. To date I know of ZERO deaths in true CLT gyroplanes that culd be remotely blamed on the gyro itself.

Adding aux tanks seems like no big deal. I am not sure if FlightExpress has a older HTL gyro or not. His might be CLT...... But it is just the same as going from heavy skywheels rotorblades up top or light Dragon Wings. Any change to the way the weight is arranged on a gyro changes the balance of things, for the good or the bad.

[Udi]

I have calculated the change in thrust line offset for my old CLT Air Command and decided the effect of the external tanks ON CLT ACs is acceptable. Assuming AUW of 550 lbs w/o the tanks, tanks weight of 10 lbs, fuel weight of 42 lbs and tanks location 15 inches below the CG. The CG is lower by 0.3" due to the tanks themselves and 1.5" when full with fuel. This is certainly acceptable.

The numbers are a little worse in a HTL AC because the tanks sit more than 15" below the CG. If we assume that the thrust line is 6" above the CG and that the tanks sit 20" below the CG, adding the tanks would lower the CG by 0.4" with the tanks empty and by about 2" with the tanks full. That would make a 6" HTL gyro into an 8" HTL gyro. That's significant!

Also, although the tanks are fairly aerodynamic, they WILL lower the center of drag a little, which adds to the already high nose-down pitching moment by the engine.

I tend to think that people who are willing to fly very-high thrust line gyros don’t completely comprehend the fragile balance of moments that make a gyro tick. The only reason a gyroplane (any gyroplane) does not tumble forward or backwards in the sky is due to this balance of moments. As long as this balance is kept, everything is hunky dory. Once this balance gets out of whack – watch out below.

Udi

[Udi]

Steven - you can do either a double hang test (search the forum for details) or a double balance test. I have a spreadsheet by C. Beaty for doing a double balance test. This forum won't let me attach an excel file so I saved it on my server. Right click on this link (http://www.qualityinformationsystems.com/gyro/CG5.1.xls) and save to your puter.

Udi

[Mike Jackson]

Good grief... The only fact Ron forgot to mention is that, historically, a high thrust line gyro is particularly lethal in the hands of a high time fixed wing ATP. Stan - I like you and I wish you were a bit more careful giving advice. This kind of wording "Kurt: I assure you that you will do just fine with those tanks. Just have a good stab set with some negative incidence...and you good to go." may come back to haunt you one day. I know you feel completely comfortable with anything that you fly but history tells another story. If someone does what you said because "you assured him" and then something happens to him you will have it on your conscience. All you can assure him is that YOU did not have a problem.

Just a little bit more entertainment for Rick...

Udi
Hey Udi,

When are you gonna get off your "high time ATP pilot" bullsh#t know-it-all high horse? What do you know about this rating anyway? When you're qualified to fly an airliner to a 50' decision height, on glide slope, on course, +/- 2 knots AND fly a gyro, then throw the first stone. Show me the FAA statistics re ATP qualified guys and gyro accident statistics. Don't lower yourself with off the cuff remarks such as the above. Stick with your engiineering savy and level of gyroplane experience.

[Udi]

Show me the FAA statistics re ATP qualified guys and gyro accident statistics.
With this kind of tone, Mike, I am not going to show you anything. Do your own legwork, if you are really interested.

Udi

[cgmg]

Kurt,

I have the bullet tanks installed on my CLT Air Command. My plumbing setup is a little different than Stan's.

Both my tanks tee into a common line going to a facet fuel pump. The fuel line is then run up parallel to my seat tank side gauge line. At the top of the sight gauge line, I installed a tee into the seat tank, and the spare tank fuel is pumped into the seat tank that way.

I fly on the main tank until I see there are two gallons left. I then start the auxiliary fuel pump, and run it for two minutes. I stop, check the seat tank level, and run it another minute, and check the level. If needed to finish the flight, after I am down to the 2 gallon level, I pump the rest up.

A couple of notes:
After I have run a gallon down, I test the pump to be sure it's still working. You can see the flow in the line if it is. This test keeps me from getting too far away to return to the airstrip fuel-wise, and finding out my aux pump is dead.
The next note is that you can get another half gallon or so of fuel out of the tanks if you pump while climbing. At level cruise, you can't empty the tanks, at least on my machine.
The last note is to not let the fuel go stale in those tanks. I frequently pour a little fuel in the aux tanks, and pump it up while I'm flying, to keep the fuel fresh. If you don't want to do that, just make sure to drain them after you've used them on that occasional long flight.

If you're not going to do a lot of flights longer than one hour, in my opinion, it's not worth the price and hassle of mounting the extra tanks. And there is some drag and weight penalty involved with having the tanks on your machine. I found that 90% of my flights are of one hour or less duration. The only reason I have the tanks at all is that I got a screaming deal on them from someone who didn't want to make the effort to install them on his machine. Knowing what I know now, after four years of flying this machine, I wouldn't have wasted the time installing them, even at the deal I got.

Just my opinion, take it for what's it worth.

[flightexpress]

Thanks Mark...

I think I'm going to make my own tanks....Kurt

[dapartlow]

Does this mean an older A/C flies like a RAF?

[GyroRon]

With a high powered engine - especially with the Water cooled Rotaxes - and the low to the ground frame - with high thrust line - and Extra especially with no horizontal stab, the answer to your question is YES! The older HTL no stab aircommands have had a ton of accidents where the pilots ended up dead, just as bad or worse than RAF. No one talks about it much because aircommand offers and encourages owners of these older aircommands to upgrade to the newer safer CLT layout. They sell a kit to convert the older machines.

the Aux tanks add significant weight below the thrustline on any gyro - HTL or CLT - so that should be a factor if a person were wanting to put a set on their machine. On a CLT machine the tanks would turn the gyro into a slightly HTL machine. On a HTL machine the tanks just make the offset even higher and ultimately more dangerous.

[dapartlow]

GyroRon, Thanks for the two cents. It seems like it's HTL vs. CLT and Stab vs. No Stab. I just bought a HTL 532a/c and I am taking lesson in Sparrow Hawk. and will have to change it over to a CLT get signed off for solo or switch CFI's which I do not want to do.

[GyroRon]

I have had the pleasure of flying two aircommands with rotax 582 engines and both were older aircommands with the CLT kit installed and the longer tail boom and factory horizontal stab. both were easy to fly and IMHO were very stable. My only beef with either of them was due to the amount of torque of the powerful engine and the short rudder, both flew " leaning " to one side at high power settings. This is not too much of a problem, but it was a pain holding side stick to keep it level. The HTL machines would have this same trait.

The cure for this would be a tall tail like the Dominator or Sparrowhawk uses. But bottom line is, these gyros flew very stable and I would fly them with confidence that I am safe from buntovers.

[cgmg]

Ron,

Even with just a 503 on our CLT AC, my gyro flies leaning to the left. I've mounted an extension piece on the center bolt of my crossover tube for the springs, which now pulls on the crossover tube from about 2.5" to the right of center. This eliminated the constant right stick pressure, but the machine still flies slightly tilted to the left.

Any ideas on a better way, other than a tall tail, to correct the little bit of lean I still have? I have been tempted to drill a small hole in the crossover tube, but am not sure any more holes in that tube are a good thing. Plus, if it's not far enough to the right, then I have to drill another one.

[GyroRon]

I was thinking the tail on the Monarch gyro would probably fix this problem as would a tall tail, but I have yet the chance to fly one to verify. Chris Wilson didn't want to let me fly his at Bensen Days.

[barnstorm2]

Mark,

It sounds like you have the short keel.

If you have the short keel you can fix it by getting the extended keel kit. This makes the gyro safer also because if a rudder cable breaks the prop blast wont kick the rudder over into the stops.

If not, I would go for tall tail.

[GyroRon]

Every aircommand I have flown - two 582 powered CLT models, and two HTL models - had a extended tail. They all leaned in flight, especially the more powerful ones.

[Udi]

My 532 CLT A/C used to lean to the left big time. I had to hold a lot of right stick at full throttle. It was so bad that sometimes, when I was rolling out of a tight left turn, I felt I was running out of right stick - not a very pleasant feeling.

I think it was so bad because I am a light weight (150 lbs) person, and with the high seat on the CLT configuration the moment arm of my light weight is further reduced, compared to a low-seat HTL configuration. I had the short (68") mast, which just compounded the problem.

This was one of the reasons I decided to sell my gyro. Summer is near and I still have no replacement...

Udi

[Mike Jackson]

My CLT 532 A/C uses a significant amount of left rudder (20+ deg) at full power and slightly less during cruise with little to no roll off tendencies. I have not yet incorporated the 1.5" rudder displacement as recommended in the A/C HTL manual (rudder leading edge 1.5" right of keel C/L). I also have a short keel.

[cgmg]

I do have the extended keel on my machine. I have corrected the need to maintain pressure on the stick to the right with my little trim spring extension, but I still have just a slight tilt to the left while flying. It's not uncomfortable or anything, but it still bothers me.

It must not be much, because no one watching me fly by has commented on it, and on some of the videos of my flying, I can't see it, but it's definitely leaning. May just live with it. I've spent the first three years constantly adjusting things, or working on broken things. This is the year I hope to break 75 hours of flight time!

[_MOL_]

Hello all.

Just seen at the AERO 2005 Messe in Friedrichshafen (Germany) on the new introduced MT-03 they made a side offset of the hotorhead. Claimed to eliminate the P-factor of the LH turning prop of the Rotax 914.

Maybe this kind of offset will reduce the left hang the Commander has.
Or any other gyro for that matter.

Does anyone have an opinion on this?

Just a thought.

[GyroRon]

Don't know but I do know I would be wating to take a closer look at that machine. It appears the rotorhead is welded to the cheekplates, not bolted! Scary!!!

The pushrods look the same. Scary!!!!

the Mast has a bolt going right through the middle of it. Scary!!!

[_MOL_]

Never mind the scary stuff, until later anyway. That we can discuss in another post.
It is made entirely in stainless steel.
If you feel like it you can look at it here: www.Autogyro-Europe.com

[_MOL_]

Lets get back to the issue.
The Aux fuel tanks.

All issues been mentioned about the placement of the A/C Aux fuel tanks, HTL, CLT ect. are correct.
That’s why I have been thinking; why not install one of these huge seat tanks on 70 litres as seen on some Dominators instead of the A/C stock. I know it will cause some issues with the throttle arrangements, enclosure, ect. But by changing the seat tank to a larger one wont move the vertical C/G nearly as much as the stock Aux tanks.
Thinking, would be best, of close to best solution if one really needs more fuel capacity.
Have anyone done this?
Other comments?

[pwendell]

Unfortunately, no one makes the high capacity seat tanks anymore. They are now rare and expensive.

[_MOL_]

Neil Hintz mentioned to me that I could get some from Australia.
I believe he (Neil) still install them on the NZ Dominators.

[Udi]

...Claimed to eliminate the P-factor of the LH turning prop of the Rotax 914.

Maybe this kind of offset will reduce the left hang the Commander has.
Or any other gyro for that matter...
P-factor is not the problem. The problem is the rolling torque. Offsetting the rotor head would not eliminate the torque; it would only relieve the need to hold counter pressure on the stick. This solution would only work at a narrow range of prop RPM, and would create the opposite problem at idle RPM. A much simpler solution is to connect the trim spring offset from center on the cross torque bar. Better yet - use a tall tail/stab in the prop wash and minimize the roll torque.

Udi

[spaceman spiff]

Had my first lesson/demo in a non CLT today, and lived to tell about it. shocking! istructor induced PIO so i could feel what it is like. Didn't go into oscillation the first time he tried to, but it did on the second try, pitches down, pitches up, throttle back, yawn, no biggy. ;)

Pwendell, My instructor showded me a blow molded dune buggy seat that holds more fuel, not really intended for fuel, but easily adaptable. sits a littel higher than normal seat too, instant CLT and increased range for 150$ or so.

[_MOL_]

P-factor is not the problem. The problem is the rolling torque.
Udi
You are right Udi, thank you for the correction.
It was what I was thinking on, but being a foreigner I mix up the English terms sometimes.
My HTL Tandem Commander also leans to the left. I also have connected the trim spring offset to the right to compensate. The push tubes are not same length to ensure equal left and right stick. 6mm or 1/4" difference I think I have.

[ben]

try this, http://www.ulparts.com/detail.aspx?ID=247

[OzyRuss]

Neil Hintz mentioned to me that I could get some from Australia.
I believe he (Neil) still install them on the NZ Dominators.

Sure can, 65 litres, real good too. ph jerry goodwin at sydney Australia #02.95259451 Used by many gyros here
good luck

[OzyRuss]

Unfortunately, no one makes the high capacity seat tanks anymore. They are now rare and expensive.


Yes they do, 65 litres, cost approx $600 aust, see other posting.......

[_MOL_]

Just the Guy I was thinking on.
I will call him and see if he has some installation dimentions.
Do you know if he has a web page or e-mail address?
Thank you Russell.

[KenSandyEggo]

The Sparrowhawk and S-H conversions are ideal for mounting aux. tanks directly on the thrust line. I looked into it and I think you can put a 10 gallon tank on the right side and an 8 gallon tank on the left side. I forgot why one side would have to be a little shorter. I laid it all out and all that would be needed are a pair of custom machined, fairly simple brackets. The aluminum tanks are already available. The mounting holes are already there on the engine. What think ye? Any S-H and S-H drivers interested? They would have saved me my landing in the desert a couple years ago. In fact, I could have made it all the way to Phoenix non-stop. (Just what I need, another project).

[OzyRuss]

No........sorry brian.
About 90% of oz gyros use his seat tanks.....40L and 65L avail, good luck......