Posted by Bret McDanel on March 30, 2009 at 3:18am
For various personal amusement and search and rescue applications, I am looking for an airframe that has a reasonably long flying time, something on the order of 1-4 hours, with bonus points for higher :)I want something easily portable, fast to set up and tear down, can glide/autorotate to safety if there is a failure.I had thought of a few different types of frames that might achieve this, either a ram air parachute or a hang glider airfoil type wing, and only have the motor on to gain altitude, just glide for some of the time, while looking over a given area.For the hang glider airfoil the Cyber Defense Systems cyberbug is similar to what I was thinking. https://www.youtube.com/watch?v=Q4klLBxGfdcWhat are peoples opinions of these types of airframes? Would a different airframe meet the initial design goals and provide better characteristics?I am particularly fond of those types of airframes because they are more portable (fold and go) and do not have large fixed wings that make them more bulky during transport, however I am open to all suggestions.
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Hi Bret
it's surprising that similar questions to yours keep cropping up every two years (or thereabouts). Even when reasonably answered the theme then looses attraction after a few days or weeks and the answers disappear in the depth of the great data vaults.
I would like to think, that everybody who ventures into the field of small flying vehicles (of any configuration) gets him/herself some reading stuff where all these fundamental questions are picked up and answered. Of course the information must be in a form which can be understood by reasonably educated people without a physics degree, but is still accurate and reliable.
Can we find anything like that here in the forum?
Nevertheless I will try to put a few things together which may help you in the selection process.
From what you wrote the vehicle must be able to transport “several” pounds of equipment over longer distances and must be able to stay in the air for at least one hour or up to four hours. The vehicle should be mainly for your “various personal amusement and search and rescue applications”. Also it should be “easily portable, fast to set up and tear down, can glide/autorotate to safety if there is a failure”.
From this and other postings of yours I have gathered the following specification:
Radio or automatically controlled aerial vehicle for SAR and general photo work.
The air vehicle should be able to carry a load of (several pounds) = 2.5kg, some of which is fuel or batteries. That leaves a real “payload” of 1.0kg
The plane should be able to stay aloft for at least 1 hour under it’s own power.
Preferably the air vehicle should be electrically powered.
One should usually not count fuel or flight batteries included in the payload, it would influence the weight increments wrongly. One can divide the total weight of a small aerial vehicle into groups of components and allocate an estimated part weight to arrive at a reasonable accurate flying weight. Below is a little table which can provide already quite reasonable figures.
Weights gram / kg ca' % of total
Wing 540.00 10
Fuselage 400.00
Stab + boom(s) 250.00 13
UC 350.00 7
Motor + gear+ prop. 500.00 10
Battery 1730.00 35
RC-gear 220.00 4
Electronic equipment 580.00 20
Payload 420.00
Total weight 4.9950 100 the table didn't format but is correctly repeated on the pdf file
As one can see the payload and the electronic equipment weigh together 1000g which is 20% of the total weight of 5 kg. The high battery weight is the result of the one hour duration requirement.
The fuselage and wings typically account for ca’ 23% (20-25) and the UC “always” takes away 7% of the total. In this case you would easily get away without an undercarriage.
The “fuel” fraction with electric models is very large if you want to fly for any length of time. Modern LiPo batteries have a power density of ca 160 Wh/kg, which however one should not drain off every time or the life will be shortened.
This particular model as represented with a few pertinent data on the attached spread sheet has been designed with good gliding parameters to afford gliding between motor running spells. A total mixed flying time of two hours is not out of reach.
For the plane, which has no name yet, I chose the pod and booms lay out with a span of around 3.2m and a length of ca’ 2m. The plane is designed to be quickly and easily broken down into it’s major components, so it can easily transported in the boot of the normal American personal car.
If you are interested I could supply you with some sketches and drawings for you to work on.
Material I had in mind for this type would be foam and fibreglass as required by the loading stresses.
I should have added that the payload of the system has to support a few pounds of equipment, between cameras, telemetry systems, fuel/batteries, and possibly other misc gear (radio repeater for example), as that is critical to selecting a proper airframe.
Replies
it's surprising that similar questions to yours keep cropping up every two years (or thereabouts). Even when reasonably answered the theme then looses attraction after a few days or weeks and the answers disappear in the depth of the great data vaults.
I would like to think, that everybody who ventures into the field of small flying vehicles (of any configuration) gets him/herself some reading stuff where all these fundamental questions are picked up and answered. Of course the information must be in a form which can be understood by reasonably educated people without a physics degree, but is still accurate and reliable.
Can we find anything like that here in the forum?
Nevertheless I will try to put a few things together which may help you in the selection process.
From what you wrote the vehicle must be able to transport “several” pounds of equipment over longer distances and must be able to stay in the air for at least one hour or up to four hours. The vehicle should be mainly for your “various personal amusement and search and rescue applications”. Also it should be “easily portable, fast to set up and tear down, can glide/autorotate to safety if there is a failure”.
From this and other postings of yours I have gathered the following specification:
Radio or automatically controlled aerial vehicle for SAR and general photo work.
The air vehicle should be able to carry a load of (several pounds) = 2.5kg, some of which is fuel or batteries. That leaves a real “payload” of 1.0kg
The plane should be able to stay aloft for at least 1 hour under it’s own power.
Preferably the air vehicle should be electrically powered.
One should usually not count fuel or flight batteries included in the payload, it would influence the weight increments wrongly. One can divide the total weight of a small aerial vehicle into groups of components and allocate an estimated part weight to arrive at a reasonable accurate flying weight. Below is a little table which can provide already quite reasonable figures.
Weights gram / kg ca' % of total
Wing 540.00 10
Fuselage 400.00
Stab + boom(s) 250.00 13
UC 350.00 7
Motor + gear+ prop. 500.00 10
Battery 1730.00 35
RC-gear 220.00 4
Electronic equipment 580.00 20
Payload 420.00
Total weight 4.9950 100 the table didn't format but is correctly repeated on the pdf file
As one can see the payload and the electronic equipment weigh together 1000g which is 20% of the total weight of 5 kg. The high battery weight is the result of the one hour duration requirement.
The fuselage and wings typically account for ca’ 23% (20-25) and the UC “always” takes away 7% of the total. In this case you would easily get away without an undercarriage.
The “fuel” fraction with electric models is very large if you want to fly for any length of time. Modern LiPo batteries have a power density of ca 160 Wh/kg, which however one should not drain off every time or the life will be shortened.
This particular model as represented with a few pertinent data on the attached spread sheet has been designed with good gliding parameters to afford gliding between motor running spells. A total mixed flying time of two hours is not out of reach.
For the plane, which has no name yet, I chose the pod and booms lay out with a span of around 3.2m and a length of ca’ 2m. The plane is designed to be quickly and easily broken down into it’s major components, so it can easily transported in the boot of the normal American personal car.
If you are interested I could supply you with some sketches and drawings for you to work on.
Material I had in mind for this type would be foam and fibreglass as required by the loading stresses.
Have fun
W.
Flugsonde03.pdf
if you don't like the idea of fixed wings, have you looked at gyroplanes/gyrocopters ?
http://home.att.net/~imsofaman/wba.htm
Thanks