What do you think is a typical configuration of an 'Air Race E' plane?

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jandetlefsen

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Air Race E | Pure Electric Motorsport

Seems like most teams are using Cassutt air frames, some are building their own from scratch and then develop their own propulsion system. What do you think they would use for motor, controller and battery, any guesses? In other words, if you had to build one, how would you do it?
 

bmcj

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You can pretty much adapt any design. The only real difference so the small size and weight of the motor compared to an IC engine, so you don’t need the bulky engine compartment. That means that the nose can be long and slender, or you can make a pusher with the prop running in laminar air, mostly clear of air disturbed by the wing or tail surfaces. It eliminates the need for a very long prop shaft that could have problems with harmonic vibrations.
 
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BJC

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Air Race E | Pure Electric Motorsport

Seems like most teams are using Cassutt air frames, some are building their own from scratch and then develop their own propulsion system. What do you think they would use for motor, controller and battery, any guesses? In other words, if you had to build one, how would you do it?
The site shows an airplane being propped, as well as right turns.

Should be interesting.

BJC
 

Victor Bravo

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The lighter weight and smaller size of the motor will allow configurations to be a lot different than the Cassutt. This is because the Cassutt was designed to be a very small airplane that balanced with a 200 pound engine on the very front. If the motor weighs 50 or 80 pounds, and the battery can go anywhere, there are probably better or cleaner configurations that can be used. Things that look more like Mike Arnold's AR-5, or a cleaned up BD-5, etc. etc.
 

Riggerrob

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Yes Victor Bravo,
And the chief advantage of an electric BD-5 configuration is that you can mount a light-weight electric motor on the extreme tail of the airplane without massive balance problems or vibrating drive shafts.

E-Racing rules are copied from Formula One aft of the firewall.
As an aside, I vaguely remember that Formula One rules specify a minimum empty weight of 500 pounds. This rule discourages racers from flying airplanes that are structurally too light and too flimsy.
IOW Minimum 500 pound empty weight encourages racers to invest in strong airframes ... reducing the risk of inflight structural failure.
The first generation of E-Racers will be stock Formula One airframes aft of the firewall. All the modifications will be firewall forward with motor, batteries, controllers, etc. all hung from a new engine mount.
Second generation E-Racers will start to separate motors from batteries with the later mounted in wing roots. I say wing roots because mounting too much weight too far outboard slows roll rates and deteriorates spin recovery characteristics.
 
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Voidhawk9

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The first generation of E-Racers will be stock Formula One airframes aft of the firewall. All the modifications will be firewall forward with motor, batteries, controllers, etc. all hung from a new engine mount.
Second generation E-Racers will start to separate motors from batteries with the later mounted in wing roots. I say wing roots because mounting too much weight too far outboard slows roll rates and deteriorates spin recovery characteristics.
I agree. The Royal Aeronautical Society ran a design competition raced in X-plane (with relaxed rules regarding motor placement) to encourage interest and see what sorts of designs emerged.
My design won. Batteries in the wing roots, and removed the tail as that wetted area is not required by the rules (but a minimum main wing area is).
 

12notes

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I think their approach matches the adage "Either design a new propulsion system, or an airframe, but not both if you ever want to finish" often heard on this board. It makes sense to use the Cassutt or another proven race plane at this time, starting with a clean sheet design would likely add years to the project.
 

bmcj

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I think their approach matches the adage "Either design a new propulsion system, or an airframe, but not both if you ever want to finish" often heard on this board. It makes sense to use the Cassutt or another proven race plane at this time, starting with a clean sheet design would likely add years to the project.
Yes, but electric propulsion is fairly straightforward and does not suffer from the myriad of failure modes that a new IC design might have. This means that you can play with the aircraft design because the propulsor is fairly well understood. Besides, many racing aircraft sport big design configuration changes while also running engines at the extreme end of their capability, so I don’t see any issues here running a new design with a new motor... it’s kind of par for the course.
 

12notes

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Yes, but electric propulsion is fairly straightforward and does not suffer from the myriad of failure modes that a new IC design might have. This means that you can play with the aircraft design because the propulsor is fairly well understood. Besides, many racing aircraft sport big design configuration changes while also running engines at the extreme end of their capability, so I don’t see any issues here running a new design with a new motor... it’s kind of par for the course.
True about the electric propulsion being straightforward. But I disagree that running existing engines at the edge of their capability counts the same as designing for a completely new propulsion system, or that most of the configuration changes would count similar to a clean sheet design. Especially not in Formula 1 air racing, while there are occasionally new aircraft with new engines, most of the radical changes seem to be a new wing of a design that is similar or identical to other wings that have flown on other racers, and a new cam/propeller on the mandated O-200.

If working with a limited time/budget, then I think modifying a Cassutt might be the only thing that could be done for around $50K in 6 months, including the airframe. Completely new designs will still take years longer, but might be cheaper.
 

Victor Bravo

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Imagine the size and general shape of the Monnett Moni that is on display in the EAA museum N107MX. This was the first 27 foot span prototype which was later clipped down to 16 foot span.

With the clipped wing it was good for 130+ MPH on a 25 HP IC engine, including the losses for air cooling the cylinders, and exhaust losses, and a hole in the bottom of the fuselage for the exhaust.

Take those losses out, and you would likely have a 140 MPH airplane.

Now add in the extra torque and achievable power from a well designed 50-60HP electric motor, and you might have 150-160 MPH. Then take 5 MPH off of that because you still have to cool the motor and batteries.

Now add back as much speed as you feel is appropriate for airframe cleanup (the Moni was square edged, no fairings, not air-sealed, etc.).

That's without building molds, without really critical laminar flying surfaces, without any 3D curvatures.
 

Map

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That's funny, the idea that electric motors are straightforward. My experience so far is the opposite (testing 2 electric aircraft projects, not racers). It involves a lot of R&D to get things working well. But once it does, the powerplant operation for the pilot is easy.
 

jandetlefsen

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I agree. The Royal Aeronautical Society ran a design competition raced in X-plane (with relaxed rules regarding motor placement) to encourage interest and see what sorts of designs emerged.
My design won. Batteries in the wing roots, and removed the tail as that wetted area is not required by the rules (but a minimum main wing area is).
That's pretty cool. Thanks for sharing
 

jandetlefsen

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I think their approach matches the adage "Either design a new propulsion system, or an airframe, but not both if you ever want to finish" often heard on this board. It makes sense to use the Cassutt or another proven race plane at this time, starting with a clean sheet design would likely add years to the project.
Yeah most teams go by that approach, however Team NL seem to start with a custom airframe design.

Designed from the ground-up, our race plane is composed of high performance, light weight composites. This ensures our airframe will have a low structural weight.
 

Creighton

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Designing cool looking airplanes to run in a computer is different than having to perform the tests and precision of starting a race with 8 airplanes on a 150 foot wide runway with a 15kt crosswind. Control on the ground and at low speeds is important and the tailless design of IONTREPID is cool looking and I really like the wing lay out but I would think that the runway handling would be unsatisfactory. You must demonstrate a take off and abort with straying 5 feet either side. That is the issue I see. I have been flying my Racer for 10 years with 3 different wings and 3 different tails and 2 different gears and it's a challenge with a conventional tail. There have been some racers with unconventional gear that were unable to demonstrate satisfactory ground handling like one built with both of the required tires in the center and the wings would drag like a sale plane. This required a change before it was allowed to compete the next year. Differential braking can steer but it slows you down on the critical take off race. Tri Gear does help if its steerable, the advantage Bruce Bohannen had in Pushy Galore was the trigear.
 

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Voidhawk9

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Thanks for sharing the real-world experience, Creighton. I wasn't aware of the 5ft rule, that's good to know.
Yes, ground-handling isn't as easy as some types, but the steerable tricycle layout keeps it more stable and manageable.
 
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