KRnet> Max Fuel tank Capacities.

[colin hales via KRnet]

Hi there,

I've been reading the "How much fuel" issue for a few days now. There are a few 
factors  I think are missing that might need to be added into the stirring pot.

First some necessary background information. My KR2 is just a standard KR2 and 
certainly not specifically designed for long distance flights more than 400 NM. 
Because we use blue foam in the wings, which melts if you get fuel on it, there 
can be no fuel in the wings, in case of a fuel leak. Blue foam is closed cell 
and therefore you don't need to spread a micro balloon slurry into the surface 
before glassing, so the benefit of blue foam is keeping the weight down and 
with the Jabiru engine, my empty weight is 560 lb. We are limited to 900 lb 
which is the original build MAUW, but strangely only in the UK? When I take a 
UK plane out of the UK, I am no longer limited as such, the MAUW is then at the 
discretion of the country you fly in, but I digress.

The Jabiru engine is 140 lb all up with Prop and has to be placed on a long 
engine frame to place the C of G as far forward as possible for one pilot. This 
creates a long nose. We did some wind tunnel testing to see what this did to 
stability, seemingly not a lot. I got the Empty C of G so far forward I had to 
move the main wheels forward 2 inches to place any weight back on the tailwheel 
with a full main tank. But then I can fly 'two up' or dual, with no C of G 
issues at all. If I fly solo, I have to put the spare passengers parachute on 
the parcel shelf behind me to make the plane fly nicely or the C of G is too 
far forward. I'm 175 Lb.

Because we can not put fuel in the wings, all we can do is fit a fuel tank 
above your feet. The biggest fuel tank I could fit in this space and still get 
my feet in past the bottom of the tank to the rudder pedals was 25 US gallons. 
Fuel burn of the Jabiru is 5US Gallons per hour giving 4 hours plus an hour of 
reserve. I cruise at 120 mph. So my endurance is 500 miles in a standard KR2 
that i can fly solo or dual with a climb rate of 800 ft at MAUW of 900 lb and 
cruise of 120 mph with the 80hp Jabiru engine at 5 US gallons on hour. That is 
fact.

You want to be careful putting too much fuel in the wings in long tanks. Why? 
Well research Aircraft Spinning Characteristics and you will find out. If you 
want to make an aircraft spin better, then go put weights on the wingtips. 
There is some 'A to B' ratio, 'A' being weight on the longitudinal Axis and 'B' 
torque created by weight and moment arm, but it was a very long time ago. If I 
remember correctly, the more weight you place away from the centre axis the 
more difficult it is to get that weight to stop spinning.  Get into a spin with 
50 gallons of fuel in long wing fuel tanks and I expect it won't come out. With 
half tanks, role to the right or left, a bit of side slip and the weight shift 
could be dramatic. I read I think from Mike that a guy was building a long 
range KR2 " For flights of shorter length he had removable wing extensions.  
These also held fuel and the day I was there he was fiddling with the fuel 
quantity sensors." The idea of fuel in the outer panels makes my eyes pop out. 
The Lear Jets I used to deal with, they could only put fuel in their tip tanks 
if the overall fuel weight was above a certain figure due to stability issues.

In Russia I had to do 1,000 NM flights between airfields or 1,150 statute 
miles, so had to carry 220 litres of fuel or a whole barrel of fuel. 58 US 
gallons. This was done by 25 gallons in the main header tank, 15 gallons in a 
fiberglass reserve tank that sat on the passenger seat and then 4 fuel bladders 
carrying 4.5 gallons in each down by the co pilot rudder pedals. Feeding the 
main header tank from the reserve tank sitting next to me meant the C of G was 
only going forward. I can fly with a 175 lb passenger with no problems but this 
fuel weighed about 200 lb. So the C of G was beyond the 6 inch aft limit we use 
here in the UK, but still within the 8 inch book figure. It was horrible to fly 
though and had no stability at all, it was truly not nice.

"So what!" you may ask? Well all the above is boring.

 The interesting fact and the one you want to know is, that I couldn't carry 
efficiently that much fuel in a standard KR2. I took off out of Nome with full 
power obviously and was requested to climb to FL100. I couldn't do it. The 
plane stayed on full power for two hours trying to lift 58 gallons up that high 
and the highest I could get was 8,500 feet and yes that was cold air. I was 
burning about 7 US gallons at full power just to lift the fuel. It took until I 
got rid of 20 Gallons of fuel to be able to climb to FL100 and throttle back. 
The issue is the jabiru's genuine 80 hp is only at sea level. I bet you are 
down to 50 HP at 8,000 feet and that's not enough to lift a heavy aircraft.

So if you have more power, that will help, except more power means more fuel 
burn. Also, a KR2S is relatively much bigger a

Re: KRnet> Max Fuel tank Capacities.

[victor taylor via KRnet]

I wouldn’t spin a KR at all. It may not come out. 

In regards to the Blue foam we still slurry it on all composite airplanes to 
prevent delamination. 

CH you are so right about just adding too much fuel. You only have so much 
power and so much wing area. Also consider the consequences if you have an 
engine failure with a very high wing loading. 

Make sure that if you do put fuel in the wings that you have two fuel pumps 
that can move fuel from both tanks. I would reserve at least four gallons for 
the header tank in case of an electrical failure. 

Fly safe!


Victor Taylor

> On Jan 10, 2023, at 07:04, colin hales via KRnet  wrote:
> 
> 
> Hi there, 
> 
> I've been reading the "How much fuel" issue for a few days now. There are a 
> few factors  I think are missing that might need to be added into the 
> stirring pot.
> 
> First some necessary background information. My KR2 is just a standard KR2 
> and certainly not specifically designed for long distance flights more than 
> 400 NM. Because we use blue foam in the wings, which melts if you get fuel on 
> it, there can be no fuel in the wings, in case of a fuel leak. Blue foam is 
> closed cell and therefore you don't need to spread a micro balloon slurry 
> into the surface before glassing, so the benefit of blue foam is keeping the 
> weight down and with the Jabiru engine, my empty weight is 560 lb. We are 
> limited to 900 lb which is the original build MAUW, but strangely only in the 
> UK? When I take a UK plane out of the UK, I am no longer limited as such, the 
> MAUW is then at the discretion of the country you fly in, but I digress. 
> 
> The Jabiru engine is 140 lb all up with Prop and has to be placed on a long 
> engine frame to place the C of G as far forward as possible for one pilot. 
> This creates a long nose. We did some wind tunnel testing to see what this 
> did to stability, seemingly not a lot. I got the Empty C of G so far forward 
> I had to move the main wheels forward 2 inches to place any weight back on 
> the tailwheel with a full main tank. But then I can fly 'two up' or dual, 
> with no C of G issues at all. If I fly solo, I have to put the spare 
> passengers parachute on the parcel shelf behind me to make the plane fly 
> nicely or the C of G is too far forward. I'm 175 Lb. 
> 
> Because we can not put fuel in the wings, all we can do is fit a fuel tank 
> above your feet. The biggest fuel tank I could fit in this space and still 
> get my feet in past the bottom of the tank to the rudder pedals was 25 US 
> gallons. Fuel burn of the Jabiru is 5US Gallons per hour giving 4 hours plus 
> an hour of reserve. I cruise at 120 mph. So my endurance is 500 miles in a 
> standard KR2 that i can fly solo or dual with a climb rate of 800 ft at MAUW 
> of 900 lb and cruise of 120 mph with the 80hp Jabiru engine at 5 US gallons 
> on hour. That is fact.
> 
> You want to be careful putting too much fuel in the wings in long tanks. Why? 
> Well research Aircraft Spinning Characteristics and you will find out. If you 
> want to make an aircraft spin better, then go put weights on the wingtips. 
> There is some 'A to B' ratio, 'A' being weight on the longitudinal Axis and 
> 'B' torque created by weight and moment arm, but it was a very long time ago. 
> If I remember correctly, the more weight you place away from the centre axis 
> the more difficult it is to get that weight to stop spinning.  Get into a 
> spin with 50 gallons of fuel in long wing fuel tanks and I expect it won't 
> come out. With half tanks, role to the right or left, a bit of side slip and 
> the weight shift could be dramatic. I read I think from Mike that a guy was 
> building a long range KR2 " For flights of shorter length he had removable 
> wing extensions.  These also held fuel and the day I was there he was 
> fiddling with the fuel quantity sensors." The idea of fuel in the outer 
> panels makes my eyes pop out. The Lear Jets I used to deal with, they could 
> only put fuel in their tip tanks if the overall fuel weight was above a 
> certain figure due to stability issues.
> 
> In Russia I had to do 1,000 NM flights between airfields or 1,150 statute 
> miles, so had to carry 220 litres of fuel or a whole barrel of fuel. 58 US 
> gallons. This was done by 25 gallons in the main header tank, 15 gallons in a 
> fiberglass reserve tank that sat on the passenger seat and then 4 fuel 
> bladders carrying 4.5 gallons in each down by the co pilot rudder pedals. 
> Feeding the main header tank from the reserve tank sitting next to me meant 
> the C of G was only going forward. I can fly with a 175 lb passenger with no 
> problems but this fuel weighed about 200 lb. So the C of G was beyond the 6 
> inch aft limit we use here in the UK, but still within the 8 inch book 
> figure. It was horrible to fly though and had no stability at all, it was 
> truly not nice. 
> 
> "So what!" you may ask? Well all the above is boring.
> 
>  The interesting fact and the on

Re: KRnet> Max Fuel tank Capacities.

[Bill Jacobs via KRnet]

Hello Colin.Thanks for the information. It's good to hear feedback from an 
actual source. Aside from drawing flak from the spin test mention, I can 
appreciate hearing sage advice from the actual participant.Regards,Bill Jacobs 
Daytona Beach, Fl. 

On Tuesday, January 10, 2023 at 06:47:08 AM EST, colin hales via KRnet 
 wrote:  
 
 Hi there, 
I've been reading the "How much fuel" issue for a few days now. There are a few 
factors  I think are missing that might need to be added into the stirring pot.
CH.
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Re: KRnet> Max Fuel tank Capacities.

[John Gotschall via KRnet]

Spin a KR2?

Hasn't at least one life been lost from spin testing a KR2?

jg





On Tue, Jan 10, 2023, 05:36 victor taylor via KRnet 
wrote:

> I wouldn’t spin a KR at all. It may not come out.
>
> In regards to the Blue foam we still slurry it on all composite airplanes
> to prevent delamination.
>
> CH you are so right about just adding too much fuel. You only have so much
> power and so much wing area. Also consider the consequences if you have an
> engine failure with a very high wing loading.
>
> Make sure that if you do put fuel in the wings that you have two fuel
> pumps that can move fuel from both tanks. I would reserve at least four
> gallons for the header tank in case of an electrical failure.
>
> Fly safe!
>
>
> Victor Taylor
>
> On Jan 10, 2023, at 07:04, colin hales via KRnet 
> wrote:
>
> 
> Hi there,
>
> I've been reading the "How much fuel" issue for a few days now. There are
> a few factors  I think are missing that might need to be added into the
> stirring pot.
>
> First some necessary background information. My KR2 is just a standard KR2
> and certainly not specifically designed for long distance flights more than
> 400 NM. Because we use blue foam in the wings, which melts if you get fuel
> on it, there can be no fuel in the wings, in case of a fuel leak. Blue foam
> is closed cell and therefore you don't need to spread a micro balloon
> slurry into the surface before glassing, so the benefit of blue foam is
> keeping the weight down and with the Jabiru engine, my empty weight is 560
> lb. We are limited to 900 lb which is the original build MAUW, but
> strangely only in the UK? When I take a UK plane out of the UK, I am no
> longer limited as such, the MAUW is then at the discretion of the country
> you fly in, but I digress.
>
> The Jabiru engine is 140 lb all up with Prop and has to be placed on a
> long engine frame to place the C of G as far forward as possible for one
> pilot. This creates a long nose. We did some wind tunnel testing to see
> what this did to stability, seemingly not a lot. I got the Empty C of G so
> far forward I had to move the main wheels forward 2 inches to place any
> weight back on the tailwheel with a full main tank. But then I can fly 'two
> up' or dual, with no C of G issues at all. If I fly solo, I have to put the
> spare passengers parachute on the parcel shelf behind me to make the plane
> fly nicely or the C of G is too far forward. I'm 175 Lb.
>
> Because we can not put fuel in the wings, all we can do is fit a fuel tank
> above your feet. The biggest fuel tank I could fit in this space and still
> get my feet in past the bottom of the tank to the rudder pedals was 25 US
> gallons. Fuel burn of the Jabiru is 5US Gallons per hour giving 4 hours
> plus an hour of reserve. I cruise at 120 mph. So my endurance is 500
> miles in a standard KR2 that i can fly solo or dual with a climb rate of
> 800 ft at MAUW of 900 lb and cruise of 120 mph with the 80hp Jabiru engine
> at 5 US gallons on hour. That is fact.
>
> You want to be careful putting too much fuel in the wings in long tanks.
> Why? Well research Aircraft Spinning Characteristics and you will find out.
> If you want to make an aircraft spin better, then go put weights on the
> wingtips. There is some 'A to B' ratio, 'A' being weight on the
> longitudinal Axis and 'B' torque created by weight and moment arm, but it
> was a very long time ago. If I remember correctly, the more weight you
> place away from the centre axis the more difficult it is to get that weight
> to stop spinning.  Get into a spin with 50 gallons of fuel in long wing
> fuel tanks and I expect it won't come out. With half tanks, role to the
> right or left, a bit of side slip and the weight shift could be dramatic. I
> read I think from Mike that a guy was building a long range KR2 " For
> flights of shorter length he had removable wing extensions.  These also
> held fuel and the day I was there he was fiddling with the fuel quantity
> sensors." The idea of fuel in the outer panels makes my eyes pop out. The
> Lear Jets I used to deal with, they could only put fuel in their tip tanks
> if the overall fuel weight was above a certain figure due to stability
> issues.
>
> In Russia I had to do 1,000 NM flights between airfields or 1,150 statute
> miles, so had to carry 220 litres of fuel or a whole barrel of fuel. 58 US
> gallons. This was done by 25 gallons in the main header tank, 15 gallons in
> a fiberglass reserve tank that sat on the passenger seat and then 4 fuel
> bladders carrying 4.5 gallons in each down by the co pilot rudder pedals.
> Feeding the main header tank from the reserve tank sitting next to me meant
> the C of G was only going forward. I can fly with a 175 lb passenger with
> no problems but this fuel weighed about 200 lb. So the C of G was beyond
> the 6 inch aft limit we use here in the UK, but still within the 8 inch
> book figure. It was horrible to fly though and had no stability at all, it
> was truly

Re: KRnet> Max Fuel tank Capacities.

[MS]

 "The Lear Jets I used to deal with, they could only put fuel in their tip 
tanks if the overall fuel weight was above a certain figure due to stability 
issues."
Filling one side full with the opposite tank being empty can cause the plane to 
tip over.  I've never seen that actually happen but have just heard this via 
hangar talk.  I imagine this is what Colin is talking about regarding 
"stability issues" with the Lear. 

In the case I mentioned re the mysterious KR that I've never heard anything 
more about, the builder had increased his wing area through adding length and 
chord.  Someday I'll learn the rest of the story regarding that extraordinary 
plane.  I'll go looking for those pictures in the meantime. 

Mike

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Re: KRnet> Max Fuel tank Capacities.

[Flesner via KRnet]

On 1/10/2023 1:13 PM, MS wrote:
Filling one side full with the opposite tank being empty can cause the 
plane to tip over.  I've never seen that actually happen but have just 
heard this via hangar talk.  I imagine this is what Colin is talking 
about regarding "stability issues" with the Lear. 


+

Line service was told to hold any differential to 100 gallon or less, do 
100 gallon from empty on one wing, 200 gallon in the other wing, back to 
the first wing, etc..  I have no clue as to what the total capacity 
was.  That much weight at the wing tip could cause control problems 
under certain circumstances.  Just make sure to avoid those 
circumstances.   None were ever "tipped" at my airport but then we 
didn't see a lot of them either.


Any fuel in the outer wing panels will reduces the amount of weight 
supported by the WAF so that is of some benefit if you go heavy with 
large amounts of fuel.


Larry Flesner
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Re: KRnet> long distance flights

[Dave Klingler via KRnet]

Using Google to search through the newsletters, I found:

Keith James
1328 E. 45 Place
Tulsa, OK 74105
(918) 745-8085

Keith James was the program chair for at least one KR Gathering and used to 
supply stub wing skins to KR builders. Unfortunately, his phone number no 
longer works.

Dave Klingler

> On Jan 9, 2023, at 5:12 PM, Flesner via KRnet  wrote:
> 
> On 1/9/2023 5:56 PM, shafferj45...@twc.com wrote:
>> Larry, I this plane was being built by Keith James, at that time, of the 
>> Tulsa area. He used to come around Dan Diehl's shop on occasion. I checked 
>> with Dan this evening, and he doesn't know where Keith or the plane are.   
>> John Shaffer
> 
> ++
> 
> I did a quick search in the airman database.  There were 13 "Keith James" 
> listed.  One in Europe, two in California, and the other 10 opted out of 
> making their info public.  No luck there. Good chance he is deceased some 30 
> years later.  Should have guessed it came out of Tulsa and the Dan Diehl and 
> Marty Roberts crowd.
> 
> Larry Flesner
> 
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Re: KRnet> Fuel tank Capacities

[Dave Klingler via KRnet]

Mike, in your photos, did that aircraft have a tail number?

Dave Klingler


> On Jan 9, 2023, at 11:57 PM, MS  wrote:
> 
> "My long-term pipe dream is to attempt to follow Colin Hales' example. Does 
> anyone have opinions about the maximum fuel capacity a KR-2S could handle if 
> built for that mission?"
> 
> Dave Klingler
> 
> ***
> 
> This puts me in mind of a KR very close to being finished that I came across 
> maybe 4 years ago...
> Mike Stirewalt
> KSEE
>
> 
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KRnet> Spinning a KR2

[colin hales via KRnet]

I got caught in wall of convergence cloud approaching Iceland. It happened so 
quicly and built so quickly, I couldn't find a way out... I tried to descend 
out of it but at 400 feet above sea level there was still no cloud base so I 
opened up the throttle and tried to climb out of it, go back some 20 miles or 
so where the was little to no cloud, go down to sea level and run in to an 
airfield on the coast. Climbing up, the artificial horizon vaccuum venturi 
froze up at about 5,000 feet. The horizon wound down and started to spin. I had 
to put one hand over it to stop getting confused. Needless to say, about 30 
seconds later, I lost control, ended up I presume upside down and pulling out 
of loop. I lost 4,000 ft in that manoeuvre, went up to VNE and then level 
again. I thought, if I hit the water at VNE that will be it, so I thought, put 
it into a spin. That is a recognised stable manoeuvre and I'll stay in the spin 
till I pop out the bottom of the cloud, carry out the standard recovery and 
continue on. Thing was, the decent rate in the spin was rapid. Not enough time 
to recover when appearing out of the cloud before hitting the water, so I 
recovered from the spin. The plane came straight out and I could recover to 
level at about 1,000 feet. I just then let go and let the plane descend on its 
own. Why not, it was trimmed out and flew level, so I just let it. It did a 
better job than I did and we came out the cloud at about 300 feet and then 
cruised along to the airport low level.

When I landed the local pilots told me that the weather phenomena did it most 
days, around the same time every day, as cold air flowed off the glaciers and 
out to sea. If there was an onshore breeze, a thick wall of cloud would appear 
about 10 miles off shore and shoot up to many thousands of feet. I should have 
just carried on and I would have popped out of the cloud this side and landed 
with no problem.

In the Uk, we stall the aircraft every year as part of the annual flight test. 
Even in a deep stall with the stick on the back stop, decent rate about 1,800 
ft/min, the ailerons still work and you can steer with the rudder and pick up a 
wing with the rudder. Its all quite civilised. So I was quite confident that 
the airplane would recover, as in the deep stall. When you let go of the stick, 
the nose drops, speed increases and the plane unstalls itself.

So yes, I intentionally spun the plane. Not allowed normally, but these were 
not normal circumstances. The KR2 was mid C of G and not too heavy at the time 
and it recovered like any other plane.

There can not be much left in my bag of luck. I think I can see the bottom of 
it. Hense why I stay at home now...

CH.

From: KRnet  on behalf of John Gotschall via 
KRnet 
Sent: 10 January 2023 14:52
To: KRnet 
Cc: John Gotschall 
Subject: Re: KRnet> Max Fuel tank Capacities.

Spin a KR2?

Hasn't at least one life been lost from spin testing a KR2?

jg





On Tue, Jan 10, 2023, 05:36 victor taylor via KRnet 
mailto:krnet@list.krnet.org>> wrote:
I wouldn’t spin a KR at all. It may not come out.

In regards to the Blue foam we still slurry it on all composite airplanes to 
prevent delamination.

CH you are so right about just adding too much fuel. You only have so much 
power and so much wing area. Also consider the consequences if you have an 
engine failure with a very high wing loading.

Make sure that if you do put fuel in the wings that you have two fuel pumps 
that can move fuel from both tanks. I would reserve at least four gallons for 
the header tank in case of an electrical failure.

Fly safe!


Victor Taylor

On Jan 10, 2023, at 07:04, colin hales via KRnet 
mailto:krnet@list.krnet.org>> wrote:


Hi there,

I've been reading the "How much fuel" issue for a few days now. There are a few 
factors  I think are missing that might need to be added into the stirring pot.

First some necessary background information. My KR2 is just a standard KR2 and 
certainly not specifically designed for long distance flights more than 400 NM. 
Because we use blue foam in the wings, which melts if you get fuel on it, there 
can be no fuel in the wings, in case of a fuel leak. Blue foam is closed cell 
and therefore you don't need to spread a micro balloon slurry into the surface 
before glassing, so the benefit of blue foam is keeping the weight down and 
with the Jabiru engine, my empty weight is 560 lb. We are limited to 900 lb 
which is the original build MAUW, but strangely only in the UK? When I take a 
UK plane out of the UK, I am no longer limited as such, the MAUW is then at the 
discretion of the country you fly in, but I digress.

The Jabiru engine is 140 lb all up with Prop and has to be placed on a long 
engine frame to place the C of G as far forward as possible for one pilot. This 
creates a long nose. We did some wind tunnel testing to see what this did to 
stability, seemingly not a lot. I got the Empty C of G so far fo

Re: KRnet> Fuel tank Capacities

[Randall Smith via KRnet]

I've had two Cessna 310s and I can tell you that the wing tanks hold 50 gallons each side and one day I was filling up at the airport. I only had 10 gals in each tank.  I didn't have my key to get in the hanger so that I could sisiphon from one and put some in the other. There was nobody at the airport to help so I finally decided to take off and go back to the house. I wasn't sure what was gonna happen when I came off the ground. that left wing dropped about 3 feet and I had to shove the rudder and turn it to get the wing up, when I did that now I'm trying to climb and crab at the same time. I decided I would never do that again. So now I dip the tank I get fuel from or I put in 20 gallons on one and then go to the other, and then come back and forth until they're both full , it was kind of scary when I took off. Sent from my iPhoneOn Jan 10, 2023, at 5:02 PM, Dave Klingler via KRnet  wrote:Mike, in your photos, did that aircraft have a tail number?Dave KlinglerOn Jan 9, 2023, at 11:57 PM, MS  wrote:
"My long-term pipe dream is to attempt to follow Colin Hales' example. Does anyone have opinions about the maximum fuel capacity a KR-2S could handle if built for that mission?"Dave Klingler***This puts me in mind of a KR very close to being finished that I came across maybe 4 years ago...Mike StirewaltKSEE   






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