Quantcast

It's a special time for revolutionary part 103 ultralight designs in Carbon Fiber… especially UL motorgliders….

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
8,621
Location
North Carolina
5 electrical hp is 32a at 115, 16A at 230v... Cheap induction motors around 75% efficient. Motor will be same power for both wirings. If the motor plate has current, you can get close to shaft hp.
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,779
Location
Port Townsend WA
The motor plate has a space for hp but was left blank. No current info either on the motor plate or anywhere. I assumed the standard 115v cord plug was 20amp 115v.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
So, I have thought a little about a basic design parameters and form for this carbon fiber ultralight design. First, weight of airframe. For weight, I look to the ZJ-Viera for inspiration. Empty weight of ZJ is 170lb and fully 60lbs of this is the engine mounting boom and Hirth F-33 with redrive and starter. ZJ empty plane without engine and boom is thus 100-110lbs and is my early goal airframe only weight.

Please make suggestions for additional CF airframes in this weight range or lighter for additional research and comparison... I don't think there are many. maybe Atos Wing....

I have researched a bit on airfoils, and it seems that the available software for airfoil selection in this weight range and speed likely has less real world testing for confirmation of airfoil performance shown in airfoil selection software and accuracy of CFD simulation (maybe software and real world iterative testing of drones has better data/software? Mr. Kempf?) When combined with the continuous span variable airfoils and the speedier CNC female mold Dspar construction, the computer models may need to be tweaked with real world results to increase accuracy. The result of these things is that I think some real world iterative testing on airfoil variations may be very valuable and that the airplane should be designed to allow switching of wings for iterative testing. Hopefully an FAA exemption for heavier than 55lb drone flight can be arranged too, to reduce human risk during testing. I think a modular approach would also be helpful for design of other systems too.

In addition, after additional research, I think that electric power is likely to be the cheapest power method for design testing, so the plane should be designed to allow MAXIMUM FLEXIBILITY for different electric motor combinations and also gas engines. The power requirement should be about 10KW/13HP but if I can stay really light and aerodynamic it could go as low as 8KW/10HP.
e-sirius motor.jpg
This is a particularly elegant electric motor installation and basic plane structure I have found: E-Sirius. Notice the super elegant direct drive motor that fits AROUND the tubular tail boom. In addition, here is an interesting electric redrive that uses the same basic plane structure: Electric Moyes Tempest. I think a more elegant drive shaft redrive would be to make the drive shaft be a hollow tube fitted over the tail boom, with bearings between tail boom and drive shaft. you could then attach multiple motors to the drive shaft via belt re drive but keep them inside the wing or inside the pod. you could use multiple cheaply available 3KW ebike motors with bicycle freewheels allowing single motor failure while retaining partial power. You could basically adapt almost any motor with different rpm capabilities to this redrive system, as well as almost any low hp gas engine (probably has to be a one cylinder engine though so it is gonna vibrate the crap out of stuff). I think this hollow drive shaft idea will work great with the low motor powers we are talking about here....

If anyone has more examples of planes that have propellers installed over the tail boom, please give me links.... I want to see what others have done.

also, any ultralights with dual propeller pushers coming out the back of a high wing would be very interesting to see too.

In addition, you could use the same plane format and put dual propellers side by side on the wings on both sides of the tail boom with direct drive or redrive motors situated in the wings. This would allow use of regular fixed propellers and I THINK that there might be some large enough for initial testing that are cheaply available from China. Not sure I would want to fly a person in front of those props though. There is really a huge flexibility for power in this basic design.

So, Design has a few basic parts:

1. Pilot pod. Wing attaches to top of pod. Pod has receiving tube for removable overhead tail boom that extends behind plane to provide structure for a motor to fit over it as well as location for a hollow drive shaft allowing huge variation in motor/gas engine redrives. Pilot pod has tri gear. Pilot pod uses F1 racecar/Glider 21G crash cage tech. Pod is less than 8 feet long from nose tip to end of tail boom receiving tube so that it can be trailered sideways and flat after tail boom removal and without removing wings.

If anyone could direct me to the latest studies and designs for 21G glider crash cages I would appreciate it....

2. Wing. Designed as a one piece integrated cantilever DSpar structure that attaches to the top of the pod. Wing can be changed to different design iterations with relative ease. Designed to use CNC cutting tech for making female mold of Dspar. Wing span is less than 35 feet to allow trailering without wing removal but could be designed with one wing removable if a longer trailerable wingspan is desired. Shorter wingspan will obviously trailer better but short wings while staying efficient really requires the gross takeoff weight to be reduced and very efficient aerodynamics allowing lower motor and battery weight. Smaller wings can be later iterations. Wing iterations with dual propeller attachments located inside wings on each side of tail boom could also be iterated.

3. pod-wing transition fairing. Each wing iteration (or pod iteration) would require a different transition fairing. The female mold for this would be CNC cut for iteration speed.

4. Removable Tail boom and tail flight surfaces. linkages designed to connect to pilot controls easily with connections made and checkable by looking above and maybe behind pilots head inside cockpit of pilot pod (or maybe under a removable pod-wing transition fairing or removable panel in top of wing.)

5. Electric Motor/Gas engine with redrive or direct drive electric that fits around tail boom. I suspect that the earliest iterations used for flight testing will be redrive electric motor setups as this can be implemented less expensively than any other power system for test flights under 30 minutes duration... well, wing internal dual prop electric redrives or direct drives may be even cheaper depending on availability of suitable cheap Chinese sourced propellers.
 

BJC

Well-Known Member
HBA Supporter
Joined
Oct 7, 2013
Messages
11,798
Location
97FL, Florida, USA
If I were planning to develop a commercial composite ultralight, I would seriously consider something configured like the all metal Merlin. Merlin Lite – Aeromarine-LSA

It would be designed to accommodate slightly larger pilots. It would have a wing span of no more than 36 feet. It would have folding, or easily removable, wings and would have a dedicated trailer, a la sailplanes.


BJC
 

Gregory Perkins

Well-Known Member
Joined
May 25, 2019
Messages
61
Location
Atlanta
I have always thought that the best FAA 103 offer was the 50 pound allowance for a water tight fuselage upon which takeoffs and landings can be demonstrated on water. First off, you get rid of all the weight associated with your wheels and landing gear. That has to be at least 25 or 30 pounds of potential weight reduction. Add that to the 50 pound hull allowance AND/PLUS the ten pound advantage from the parachute rules. ( allowance greater than chute weight ) So we are now talking about a 314 pound airplane with no landing gear. You could still always land on skids when needed and water not available and you could use a kart to take off with
just like hang gliders. At this weight I believe we could find some extraordinary 4 stroke reliable motors and still have a rugged airframe.
 

peter hudson

Active Member
Joined
May 24, 2020
Messages
28
... empty plane without engine and boom is thus 100-110lbs and is my early goal airframe only weight.

Please make suggestions for additional CF airframes in this weight range or lighter for additional research and comparison... I
Rol Klingberg's 15 meter foot launched wing is still coming in at about 105 lbs...his videos will show you his materials and his construction trades. It's not yet finished so time will tell on final weight and structural adequacy.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
Why dual motors to a common shaft?
I like the redrive over the tail boom structure for the low power drivetrain like this. I think it might reduce redrive weight penalty quite a bit while keeping structurally strong and having good bearing load balance. And two motors should balance forces on the shaft and bearings better than a single belt redrive on a single motor. The biggest disadvantage of this hollow driveshaft idea is the non standard propeller design.

Obviously redrive on tube shaft can be done with one 10KW motor. I was showing a design where multiple motors could be used. In this case it would be 2 - 5KW motors, which costs less than 1 - 10KW. Where it really starts getting cheap is 3 - 3.3KW motors or even 4 2.5KW. Added complexity might be a problem, but it really isn't a huge amount more complex. For the testing phase, cheaper may be a great feature. overall efficiency may not be as important if your test flights are radio controlled drone flights with less than 20 min duration on each set of batteries.

The simplest solution is the tube shaft motors that fit over the tail boom.... I haven't found a suitable 10KW hollow shaft motor though yet. That motor could be pretty expensive.

potential advantages beyond cost for multiple motors on one shaft: the motor pully hubs in each motor's redrive can be made to freewheel one direction, allowing partial power to continue even if one motor or more motors is not operating. This might allow a motor to fail without complete loss of power. Also, might allow an overheated motor to rest, or allow shutting down some motors to let still running motors to stay in a more energy efficient operating torque in modes of flight requiring less power (like higher altitude level flight?).

also, if belts are pulling from two sides of the shaft equally, pressure on shaft and bearings underneath the common shaft pulley will be approximately equal with a slight offset.

There are obviously some disadvantages to multi motor including possibly more paths to complete failure of drive shaft. Also, bigger motors tend to have a higher efficiency, so better use of the batteries to make thrust. But this efficiency may be lost if you are needing to run a big motor at low power for longer level flight.
 

WonderousMountain

Well-Known Member
Joined
Apr 10, 2010
Messages
2,106
Location
Clatsop, Or
Consider strakes,
You can make them a wing attachment point,
going from your front bulkhead, to you seatback.
& it's a part that actually makes sense in carbon.
I was going to put some gauges in round lightholes.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
Consider strakes,
You can make them a wing attachment point,
going from your front bulkhead, to you seatback.
& it's a part that actually makes sense in carbon.
I was going to put some gauges in round lightholes.
Strakes on a high wing? Or are you suggesting a "mid high wing" where the head is above the wing in a bubbled area?

I am not figuring out where you would put the strakes on a high wing.

If I went to a low wing design, strakes would work too I think.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
The high wing/high tail boom with the propeller around the tail boom is one design. If a normal motor is needed then a low wing design might be best. This is similar to the low wing design I am thinking of: Airsport Song

However, I think that a single tail boom might be preferred, to protect the propeller from rocks better and to make the control system simple and light.
 

opcod

Well-Known Member
Joined
Aug 28, 2010
Messages
72
Location
Canada
Don't think too much about the motor. IF you plan on a 10kw.. it's way too small anyway. 10kw is to be run at 96%, so max power is less than 10kw, at mostly max 1min. So 7kw will be ended as usable and 7kw is not enought to sustain. If it's something like fabric and ultralight.. different, but if the plan is only to be in the air.. it might perhaps.
 

peter hudson

Active Member
Joined
May 24, 2020
Messages
28
do you have links to Rol Klingberg's videos? build log?
Here's a link to one of his material trade videos. from there you can see all the rest. it's a few years worth of sharing design details, structural test articles, load tests, failed processes, fixed processes, materials, flying wing design etc. Plan on losing a few hours!


-Peter-
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
13HP/10KW is the FAA calculated maximum for an ultralight that has cantilever wings and an enclosed cockpit with other slick aerodynamics as I calculated for a specific super clean design..... per AC103-7. actually there is a bit of range depending on some of the variables, so that could move up or down a bit.

While it seems too low compared to the existing 103 ultralights, there are not many actually legal ultralights that have low weight and extreme attention to clean aerodynamics. And doing calculations assuming 5% drivetrain loss and 20% loss in propeller efficiency, and assuming a sink rate of about 200 ft per min for an efficient design, you can still get a good 500 ft per min climb rate on 13HP for a plane that weights 460lbs gross.

Calculations:
500ft/min +200ft/min =700ft/min = 11.67ft/sec

so it takes 11.67 HP to climb at 500ft/min for an ultralight that weighs 550 lbs. gross.

13HP * .75 = 9.75 HP available after prop and drivetrain losses. This should actually be improvable.

9.75hp * 550lbs/11.67hp = 460lbs gross weight ultralight with a 200ft/min sink rate should have at least 500ft climb on 13HP.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
Also, for the motors, I am talking motors that have 13hp/10Kw continuous ratings which is what it can sustain in level flight. for a short period of takeoff climb, these motors will be capable of more than this before over temping which can improve takeoff climb rate and climb angle for the first few minutes of flight if the throttle allows the motor to go this high.

I don't think the FAA has been asked about this case yet though. The question is if a throttle on an electric motor that allows higher than rated power for a short period would count as full throttle and thus the motor would have to be rated at it's short use power instead of it's continuous power by the 103-7 calculations. I think this problem would be completely avoided by having the throttle not allow levels past continuous.

The other issue is of course that 103-7 uses the manufacturers STATED power, not actual power for the calculation. So motors that understate are going to be more desirable than motors that overstate...... This likely means that the best motors to choose will be motors created for a class of vehicle that has a legal maximum power allowed for some other reason... like motors for mopeds in some countries for example. There is a big incentive to understate power on a motor but provide more actual HP to give customers a hotter product.
 

patrickrio

Well-Known Member
Joined
Aug 15, 2020
Messages
46
I think part of the current "revolutionary opportunity for new part 103 designs" comes from being able to build light and efficient carbon structures for cheap that thus allow lower power to fly effectively. The lower power required, the less you need to spend on motors and batteries. With electric power, you might even get into a performance space that actually allows decent times aloft with continuous power without landing. Gas powered also should benefit from lower power thus cheaper engines and less fuel required for a given flight time (but I think there is a limit here as low horsepower basically means single cylinder and relatively high vibration....). I believe the current part 103 distance record is held by a Mitchel wing, and it should be possible to build an ultralight capable of improvement to that efficient design with carbon fiber.
 

peter hudson

Active Member
Joined
May 24, 2020
Messages
28
I think part of the current "revolutionary opportunity for new part 103 designs" comes from being able to build light and efficient carbon structures for cheap that thus allow lower power to fly effectively. The lower power required, the less you need to spend on motors and batteries.
I agree with this line of thinking. I think a great example is the Millennium with a couple of hobby motors.


-Peter-
 
Top