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RC Fuels Nitromethane, Castor Oil, Synthetic, heli fuel, 4 stroke, etc...Fuel Q&A is here!

Is home brew fuel a lot cheaper?

Old 06-09-2008, 06:46 AM
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Default Is home brew fuel a lot cheaper?

Hi guys.

I am thinking of blending my own fuel. I fly heli's mostly and my Raptor 90 is a thirsty bird. Currently I fly with 15% Nitro, 18% Klotz 198 or Klotz 200 oil.

Was just wondering if it's worth the trouble costwise to bled ones own fuel.

Marcel

Old 06-09-2008, 11:55 AM
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Default RE: Is home brew fuel a lot cheaper?

It is really decided by the cost of materials locally so if you can supply that and the local fuel costs in the shops one can compare the benifits better

Its is often nitromethane that is killing you in costs
Example is nitro methane is mostly a nitrogen and oxegen molicule and very little carbon and hydrogen the fuel stuff that burns and is more like liquid oxegen in term of fuel value

This tends to result in a multiplier effect in costs benifit ratios
A 10% nitro fuel mix compared to 5% nitro mix wont often be simpe 5% difference
It will often incur a 20% increase in running costs due to the multiplier effect

Simplex Example ......

If your helicopter for example used 100% nitro instead of 100% methanol the helicopter would at WOT require 4.5 times as much fuel to go through the engine but you would get some thing like double the power
So in effect to get the same power the 100% nitro engine could run at half gas and would use 2.25 times as much fuel to do the same work

As nitro methane costs often tens times as much as methanol we can see that high nitro fuel makes running of engine more expensive but we gain more power from nitro as it supplies more oxegen to burn and extra nitrogen to increase compression and best for heli is the high nitro makes the tuning needle requirements less critical more wide band

A 30% nitro fuel will supply the engine with 60% of its oxegen needs without extracting the oxegen from the air and make the engine less likely to quit

Using a low nitro fuel in a heli will demand a high skill requirement for tuning
if your mechanically challenged for tuning engine the higher nitro fuels are the way to go
A single engine event stopping in flight that breaks Heli gear could easily wipe out any small saving from using higher nitro fuels which will be less likely to quit


VERY Simplex Example of fuel tank fly time nitro ratios a bit on the extreme end to show the issues rather than exact imperical factual costs

Cost to run for heli per gallon on 100% meth@ 0% nitro say $20 a gallon makes say 10 flights of 20 minutes per gallon ~$2 per flight
Cost to run for heli per gallon on 90% meth@ 10% nitro say $25 a gallon makes say 9 flights of 20 minutes per gallon ~$2.70 " "
Cost to run for heli per gallon on 85% meth@ 15% nitro say $30 a gallon makes say 8flights of 20minutes per gallon ~$3.75 " "
Cost to run for heli per gallon on 80% meth@ 20% nitro say $35 a gallon makes say 7 flights of 14 minutes per gallon ~$5.00 " "
Cost to run for heli per gallon on 75 % meth@ 25% nitro say $40 a gallon makes say 6 flights of 20 minutes per gallon ~$6.60 " "


From this very simplex example where we left out oil and other effects we can see that 25% nitro could easly cost nearly double the cost of 15% nitro per fly time ratio and close to 4 times zero nitro rates

The point is to show where the real costs are to be found and therefore the real costs to be saved can be found

Often a heli involved in simplex hover and non acro work would be better to look at two options buy a tuned pipe and reduce the nitro from 15% down to 5 % or buy a engine 20% bigger as often the cost of 5 % fuel in the shops doesn't make it interesting to make your own
Usually the high nitro fuels are more interesting to make you own home brew in terms of most cost benefit saving

Using higher ratios of Castor oil if you can tolerate the gumming up issues can help reduce oil cost as often Castor is 1/2 the cost of synthetic kloz oil types
A popular soulution is 15% Kloz and 3% castor to replace 18% Kloz
But sometimes 10% Kloz and 10% Castors =20% oil total to replace 18% Kloz have been seen
Even more extreme is 25% Castor no kloz to replace 18% kloz but rarely found on Heli motors

For semi serious acro keeping the fuel at 15% and getting a lager engine and a tuned pipe will return better saving coupled with making your own home brew or tweaking the 10% from the shop with a adding some extra nitro to go to 15% (assuming your oil ratio wont drop to low )

The more flights and more fuel you use in a year will also kick in as a factor

a guy who fly 2 flights a month would probably not benifit so much as a guy who fly's 20 times a week

Simplex Examples are nitromethane costs are in USA
~$50 a USA gallon ( $60 a uk gal ) in single gallons
A 55 gallon (48 gallon UK) of barrell of Nitromethane works out at ~$15 a USA gallon ($18 a UK gallon )

In europe the costs are easly double the USA for all ingredients
expect
$12 to $20 a UK gallon for methanol
$20 to $50 a UK gallon for castor oil
$40 to $80 a UK gallon for synthetic oil
$80 to $140 a UK gallon for nitro methane


I don't know South Africa since I visited last in 1991 but I imagine prices are more similar to Europe than US


Realy and truely to do a lot of full blown acro with 3D acro with 30% it starts to become a choice between the moving house or second holiday or the divorce /alimony or similar if your not rich

It is probably much cheaper with lipos that give 100 cycles per pack than to do 30% nitro or change down to a 50 sized heli

Bigger heli non acro fuel cost with gasoline are generaly the cheapest solutions
The cheapest fuel but not cheapest engine is turbines on kerozene

Bear in mind to mix fuels you need often to get 5 to 10 gallons of fuels materials to mix and most household insurance only covers you for 1 gallon and most car insurance only covers you to carry 1 gallon which often in Europe stops most people making their own home brews even its cheaper


balsaeater

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