I used the manufacturer's specs on TBO and Fuel consumption, figuring they all pad their numbers about the same amount. The Big Twin has a bit less HP than the ½VW, and would therefore consume a bit less fuel (air cooled engine GPH is pretty predictable), but even at 2gph, the cost per hour to operate is under $8/hour, which is still a pretty good deal. If a 1,200 hour TBO equates to 10 years of flying, then the advertised 3,000 tbo on the Big Twin (an presumably most other similar conversions) would be about 25 years worth of flying.1200 hour TBO... for most ultralight pilots that'd be between 10 and 20 years of flying.
Used/rebuilt Cuyuna engines (35HP) can be a great deal, and parts are readily available and cheap. Like all 2-strokes, though, not very fuel efficient (4GPH).
Half VWs are in the same HP and price range as the Big Twin ($4650 for 45HP, $3650 for 37HP), lighter (85 lbs, about the same as a Cuyuna or 447), but don't do well with redrives. Mine burns 2 GPH (I suspect 1.25 for the Big Twin may be optimistic).
Why not get exact pricing on the egull powerplant. The eGull uses zero powertrain and there are atleast two eGull aircraft flying with Zero powertrain and doing well. It is a clean design and Mark suggests 70mph @~4KW power. So here is the powerplant that can be used:But this is a discussion about "Low Budget Ulralights", so we have one more powerplant to consider... Electrics.
We have all hear the claims of $1/hour flight costs of electric planes, with an endurance of 40 minutes. What we're not normally told is that the batteries for such a plan will run at least $5,000. A 40ish HP motor will run about $3,500, and the controller will likely be another $1,000. That's $9,500.
The main problem with all the ½VWs is that you can't use a redrive, so you take a big hit in prop efficiency due to the high rpm / small prop. The main problem with the Big Twin is the weight... most ultralights can't afford the extra 35 lbs. Having a starter is nice, but far from necessary, and note the battery isn't included in the engine weight. But if you can afford the weight, there's a lot to like about it. I don't know if a Big Twin is feasible without a stater; hand propping an engine with a redrive isn't easy. 2-strokes with redrives have pull starters; you don't hand prop them.The Hummel ½VW's look like nice little engines. But when comparing to the Big Twin, we have to keep in mind that that 85 lb at $4,550 is with no prop, starter, or alternator. The Big Twin comes in at $5,500 and 120 lb, but that includes Prop, starter, alternator, and cooling fan (even though it does not have the fan in any of the pictures of the Backyard Flier). I'm not sure about the weights, but a quick search of the interwebs gives me $4,975± for a ½VW set up like the Big Twin - that Redrive has to cost something...
To get 30 minutes at 27 hp (20 kW), you'll need 10 kWh of battery, or slightly more than 3 of those 3.3 packs, running you $6,000 on top of the $7,600 for the bike, so a total of $13,600.
Alright, that makes it a bit more affordable. :gig:It is not $13600 for 10KWhr battery but $9895 today...completely off the shelf. The DS has a 10KW battery today with 54HP motor (40HP continuous) and with the 2017 will probably increase this to 10KWhr usable.
Again UL like egull can fly on 4KW power @70mph. That is 2hr flying time with the DS powerplant. It is doable today... but is it cheap...no; definitely not for this thread on low budget UL.
When stuck with a silly 254lb limit, then yes.Batteries are still, and always will be, very heavy compared to a tank of gasoline, which is problematic for [artificially] weight limited ultralights.
No, that was suggested, but the FAA didn't buy it. Batteries are included in the 254# empty weight, you don't even get the 30# fuel allowance.HOWEVER... I have read a an article or two, and seen a couple of videos (one on the eGull, one on the electric Lazair) that allude to the FAA seeing the batteries as "Fuel", and saying a 5 gallon volume of batteries is the same as a 5 gallon volume of gas (as long as the batteries are removable) - so their weight is not counted against the empty weight of the plane.
Mr. Heistand (nheistand) has not been active here at HBA for some time, and his YouTube account shows nothing about a Siamese V Twin in development. Can you go into more detail?Norm Heistand is working on a 36hp engine under $1000. Two 18hp single cylinder engines coupled to make 36hp under 80 pounds.
Norm has a recent thread on the yahoo group: https://beta.groups.yahoo.com/neo/groups/Small4-strokeEngines/conversations/messages/16387Mr. Heistand (nheistand) has not been active here at HBA for some time, and his YouTube account shows nothing about a Siamese V Twin in development. Can you go into more detail?