3 point vs. wheel landing?
01-09-2014, 11:40 AM
#77
You are welcome, Bob
.............and that is landing left to right:
http://www.rcuniverse.com/forum/ques...ir-planes.html
.............and that is landing left to right:
http://www.rcuniverse.com/forum/ques...ir-planes.html
01-09-2014, 11:59 AM
#79
OK, I used the formulae that we were discussing a couple of weeks ago.
If that Pitts is the 2-seater, its max weight is about 1700lbs.
At the given scale, it should ideally weigh 51 lbs. Buuut, it might be expected to fly better at 80lbs.
So, your 45lbs is a light-weight.
If that Pitts is the 2-seater, its max weight is about 1700lbs.
At the given scale, it should ideally weigh 51 lbs. Buuut, it might be expected to fly better at 80lbs.
So, your 45lbs is a light-weight.
Bob
Last edited by sensei; 01-09-2014 at 12:04 PM.
01-09-2014, 12:30 PM
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Well, the "scale" weight for the model would be 51lbs.
In the discussion which we had, it was suggested that a scaling factor of 3.5 was often used, in place of the normal factor of 4.
This factor (3.5) permits many scale models to be built to realistic weights.... but, it's an arbitrary figure, having no basis in mathematics.
I doubt that the model would fly better at the higher weight ... but, some of the scale fliers apparently swear by it, because it forces you to open out the radius of manoeuvres and such, which takes time.
Come to think of it, our discussion was over at RCG, so you may not have taken part. The OP had a model bipe of about 1/4 scale. But, to build to a scale weight, he'd have to gotten the weight down below 10lbs, or something ridiculous. Using a factor of 3.5, he could build his plane to about 15 or 16lbs, which is quite achievable.
The problem of scale weight becomes insurmountable as you get to 1/6 scale and beyond.
As I recall, we pretty much decided that WCL is of no real value; this after applying the formula to various full-sized aircraft. It just didn't hold any validity.
I made the wing-loading to be in the region of 370z per square foot ... if the model weighs 51 lb. There's a little over 22 sq ft of wing.
In the discussion which we had, it was suggested that a scaling factor of 3.5 was often used, in place of the normal factor of 4.
This factor (3.5) permits many scale models to be built to realistic weights.... but, it's an arbitrary figure, having no basis in mathematics.
I doubt that the model would fly better at the higher weight ... but, some of the scale fliers apparently swear by it, because it forces you to open out the radius of manoeuvres and such, which takes time.
Come to think of it, our discussion was over at RCG, so you may not have taken part. The OP had a model bipe of about 1/4 scale. But, to build to a scale weight, he'd have to gotten the weight down below 10lbs, or something ridiculous. Using a factor of 3.5, he could build his plane to about 15 or 16lbs, which is quite achievable.
The problem of scale weight becomes insurmountable as you get to 1/6 scale and beyond.
As I recall, we pretty much decided that WCL is of no real value; this after applying the formula to various full-sized aircraft. It just didn't hold any validity.
I made the wing-loading to be in the region of 370z per square foot ... if the model weighs 51 lb. There's a little over 22 sq ft of wing.
Last edited by bogbeagle; 01-09-2014 at 12:37 PM.
01-09-2014, 01:54 PM
#81
Well, the "scale" weight for the model would be 51lbs.
In the discussion which we had, it was suggested that a scaling factor of 3.5 was often used, in place of the normal factor of 4.
This factor (3.5) permits many scale models to be built to realistic weights.... but, it's an arbitrary figure, having no basis in mathematics.
I doubt that the model would fly better at the higher weight ... but, some of the scale fliers apparently swear by it, because it forces you to open out the radius of manoeuvres and such, which takes time.
Come to think of it, our discussion was over at RCG, so you may not have taken part. The OP had a model bipe of about 1/4 scale. But, to build to a scale weight, he'd have to gotten the weight down below 10lbs, or something ridiculous. Using a factor of 3.5, he could build his plane to about 15 or 16lbs, which is quite achievable.
The problem of scale weight becomes insurmountable as you get to 1/6 scale and beyond.
As I recall, we pretty much decided that WCL is of no real value; this after applying the formula to various full-sized aircraft. It just didn't hold any validity.
I made the wing-loading to be in the region of 370z per square foot ... if the model weighs 51 lb. There's a little over 22 sq ft of wing.
In the discussion which we had, it was suggested that a scaling factor of 3.5 was often used, in place of the normal factor of 4.
This factor (3.5) permits many scale models to be built to realistic weights.... but, it's an arbitrary figure, having no basis in mathematics.
I doubt that the model would fly better at the higher weight ... but, some of the scale fliers apparently swear by it, because it forces you to open out the radius of manoeuvres and such, which takes time.
Come to think of it, our discussion was over at RCG, so you may not have taken part. The OP had a model bipe of about 1/4 scale. But, to build to a scale weight, he'd have to gotten the weight down below 10lbs, or something ridiculous. Using a factor of 3.5, he could build his plane to about 15 or 16lbs, which is quite achievable.
The problem of scale weight becomes insurmountable as you get to 1/6 scale and beyond.
As I recall, we pretty much decided that WCL is of no real value; this after applying the formula to various full-sized aircraft. It just didn't hold any validity.
I made the wing-loading to be in the region of 370z per square foot ... if the model weighs 51 lb. There's a little over 22 sq ft of wing.
Bob
01-09-2014, 03:51 PM
#82
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OK, I used the formulae that we were discussing a couple of weeks ago.
If that Pitts is the 2-seater, its max weight is about 1700lbs.
At the given scale, it should ideally weigh 51 lbs. Buuut, it might be expected to fly better at 80lbs.
So, your 45lbs is a light-weight.
If that Pitts is the 2-seater, its max weight is about 1700lbs.
At the given scale, it should ideally weigh 51 lbs. Buuut, it might be expected to fly better at 80lbs.
So, your 45lbs is a light-weight.
My favorite part about this airplane is before or after I land it I have an unsuspecting "victim" grab it by the vert. stab and walk it back to the pitts. The look on their faces when they pick up the tail and their shock at how heavy this airplane seems is priceless!
01-09-2014, 04:20 PM
#83
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I have a much lighter electric Hyperion Samson II that I've campaigned for two seasons now. I can three point this, but I must say that I want to fly scale and fly in on the mains. Here's a video that my 8 year old daugther tool with a tablet this past July.
I try to come in with scale speed. I'm afraid this is the only video that I have of this particular aircraft, but I assure you, with the light wing loading you can 3 point this thing on a quarter...
http://youtu.be/pDdFyfPUd38
I try to come in with scale speed. I'm afraid this is the only video that I have of this particular aircraft, but I assure you, with the light wing loading you can 3 point this thing on a quarter...
http://youtu.be/pDdFyfPUd38
01-09-2014, 05:16 PM
#84
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Here's a video where I managed to nail it, but this typically happens 1 out of every 7 flights...
Most who see this airplane on the ground don't believe it will fly well, let alone land!
http://youtu.be/nS5_wDJZCGY
01-09-2014, 05:20 PM
#85
Oh my! You are too kind with your comments!
My favorite part about this airplane is before or after I land it I have an unsuspecting "victim" grab it by the vert. stab and walk it back to the pitts. The look on their faces when they pick up the tail and their shock at how heavy this airplane seems is priceless!
My favorite part about this airplane is before or after I land it I have an unsuspecting "victim" grab it by the vert. stab and walk it back to the pitts. The look on their faces when they pick up the tail and their shock at how heavy this airplane seems is priceless!
How good is the shock absorbing (no spring) characteristic of the main train?
I have found this article about landing full scale trikes:
http://www.google.com/url?sa=t&rct=j...,d.cWc&cad=rja
01-09-2014, 05:34 PM
#86
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Lnewqban,
If you watch the flight, this is the second flight where I am checking the CG. It's spot on - maybe a little heavy to the tail. As to the technique, watch the video. The landing gear is balsa wood over Aluminum plate bent to suit. Not much give at all.
I just keep the speed up and pick up the centerline of the runway and reduce throttle - but am fearless if I need to go around. Too slow and one bounce and it's all over - i throttle up and go 'round.
Ross
If you watch the flight, this is the second flight where I am checking the CG. It's spot on - maybe a little heavy to the tail. As to the technique, watch the video. The landing gear is balsa wood over Aluminum plate bent to suit. Not much give at all.
I just keep the speed up and pick up the centerline of the runway and reduce throttle - but am fearless if I need to go around. Too slow and one bounce and it's all over - i throttle up and go 'round.
Ross
Last edited by Rosster6028; 01-09-2014 at 05:34 PM. Reason: Spelt Too with To (I hate that)...
01-09-2014, 07:50 PM
#89
The things I really like about hyper light airplanes is they are predictable in all attitudes, they fly 3D very well, they fly precision very well if properly setup, and they land real gentle making them much more difficult to destroy on landings. Here is a video of second day, third flight of my 52% Extra 300 SP 150" span, 144" length flying on a DA 200cc with stock exhaust.
Bob
52% 2nd Day out 2 years ago
Bob
52% 2nd Day out 2 years ago
01-10-2014, 04:01 AM
#90
Here is another 3 year old video messing around at the lake with my 55% Extra 260 with a span of 164", and a DA 200cc for power, keep in mind that most airplanes this size are running something like a 3W 342cc or larger power plant.
http://vimeo.com/12393389
Bob
http://vimeo.com/12393389
Bob
01-10-2014, 04:27 AM
#91
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I expect your Extra 260 is very light. What does it weigh ... 60lbs?
Anyway, I ran the figures for scale weight and power (ignoring Re), just to see how they sound to you.
At 52% scale, the weight should be in the order of 124lb, with power of 19hp.
The scale bods would use their fudge-factor, making the weight as high as 172lbs and needing 26 hp.
I see that you have 19hp, whereas the 342 is claimed to develop 30. Obviously, yours is different style of flying to that of the full-sized.
It would be easy to build it down to 124lbs, at this scale, of course. So, perhaps there is no need for a fudge-factor.
Anyway, I ran the figures for scale weight and power (ignoring Re), just to see how they sound to you.
At 52% scale, the weight should be in the order of 124lb, with power of 19hp.
The scale bods would use their fudge-factor, making the weight as high as 172lbs and needing 26 hp.
I see that you have 19hp, whereas the 342 is claimed to develop 30. Obviously, yours is different style of flying to that of the full-sized.
It would be easy to build it down to 124lbs, at this scale, of course. So, perhaps there is no need for a fudge-factor.
Last edited by bogbeagle; 01-10-2014 at 11:44 PM.
01-10-2014, 05:22 AM
#92
The 260 is 53 lbs. with around 2900 inches of wing area and the 300 SP is 48 lbs. with around 4500 of wing area, that places them in the wing loading area of around 24-25 ozs. and a cubed loading of less then 5. Full scale aerobatics are getting closer to what we are doing with our models every day, so I don't know if we are really that far apart anymore. You spoke of a 1/4 scale something or the other that you felt was out of scope of trying to get to 10 lbs. using your formula and 15 or 16 lbs. was more realistic, but the truth is I built and flew a structurally modified 1/3 scale Lanier Laser 200 with a 97" span and a DA 50ccfor power that weighed 15 lbs.8 ozs. and the same with a 40% Carden Extra 260 that weighs 28 lbs. with a DA 100cc for power. so a 1/4 scale @ 10 or 11 lbs. is a very achievable goal in my book, but maybe that's just me.
Here is a 6 year old video of my Carden 260. double click on video to enlarge.
http://www.icanflyrc.com/JRFlyin/JH_...es/Bob260.html
Bob
Here is a 6 year old video of my Carden 260. double click on video to enlarge.
http://www.icanflyrc.com/JRFlyin/JH_...es/Bob260.html
Bob
Last edited by sensei; 01-10-2014 at 05:38 AM.
01-10-2014, 05:44 AM
#93
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OK, well the Extra 260 (full-sized) would need an engine of about 650 hp for it to approximate the performance of your model ... without adding any weight. In other words, your model has about 2.5 times the "scale" power. (I am assuming that the 260 relates to the power of the engine)
Yes, we were discussing a 1/4 scale biplane, a Starduster Too, which weighs about the same as the Extra. Its "scale weight" would be 6.6lbs ... but, using the "fudge factor", the allowable weight would be 13.3lbs. (I just did the figures anew, rather than from memory) At 1/4 scale, the span would be just 72".
I reckon that it would be difficult to make a 6-foot biplane weigh in at under 7lbs ... though I dare say it's not impossible. You clearly build exceptionally lightly.
We know from experience that a 6-foot bipe, weighing 13lbs, will work just fine.
Thing as, as the scale shrinks, it gets even more difficult. The same biplane at 1/6 scale, would have a "scale" weight of just 1.3 lbs, and a span of 48 inches. Now, I would call that plain impossible to achieve. Even using the scale "fudge-factor", you'd only have 3.2 lbs to play with ... still a very tall order.
Those figures are about right for the Extra, too, though the span would be 74" at 1/4 scale.
Yes, we were discussing a 1/4 scale biplane, a Starduster Too, which weighs about the same as the Extra. Its "scale weight" would be 6.6lbs ... but, using the "fudge factor", the allowable weight would be 13.3lbs. (I just did the figures anew, rather than from memory) At 1/4 scale, the span would be just 72".
I reckon that it would be difficult to make a 6-foot biplane weigh in at under 7lbs ... though I dare say it's not impossible. You clearly build exceptionally lightly.
We know from experience that a 6-foot bipe, weighing 13lbs, will work just fine.
Thing as, as the scale shrinks, it gets even more difficult. The same biplane at 1/6 scale, would have a "scale" weight of just 1.3 lbs, and a span of 48 inches. Now, I would call that plain impossible to achieve. Even using the scale "fudge-factor", you'd only have 3.2 lbs to play with ... still a very tall order.
Those figures are about right for the Extra, too, though the span would be 74" at 1/4 scale.
Last edited by bogbeagle; 01-10-2014 at 06:46 AM. Reason: erred in my estimations
01-10-2014, 07:38 AM
#94
01-10-2014, 08:09 AM
#95
In the end lighter flies better and gives the operator more options for his or hers flight envelope that includes landings, if you want to fly scale a lighter airframe can fly scale just like a heavy airframe, it will just perform it easier and safer without dumping a wing for many of those that do not possess energy management skills as illustrated in the landing videos earlier in this thread, but setup is still key. If your airplane is built truly light you always have the option to place that dead weight in your airframe center mass area on the C/G precisely in the place it should go. This keeps the weight off your long moments like wings, tail feathers, and fuselage area aft of the C/G. Another thing to keep in mind is reynolds numbers work in our favor the larger an airplane gets and works against us the smaller it gets, that is why it is so important to keep them light.
Oh here is a little airplane I built for a buddy a few years ago, 56" span, and 2.5 lbs. ready to fly, it could have been a little lighter but he wanted an OS .32 in the nose forcing me to mount the flight battery pack as far back in the tail as I could go with a removable hatch instead of the .15 I wanted to use in the nose...
Bob
Oh here is a little airplane I built for a buddy a few years ago, 56" span, and 2.5 lbs. ready to fly, it could have been a little lighter but he wanted an OS .32 in the nose forcing me to mount the flight battery pack as far back in the tail as I could go with a removable hatch instead of the .15 I wanted to use in the nose...
Bob
01-10-2014, 03:38 PM
#98
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The things I really like about hyper light airplanes is they are predictable in all attitudes, they fly 3D very well, they fly precision very well if properly setup, and they land real gentle making them much more difficult to destroy on landings. Here is a video of second day, third flight of my 52% Extra 300 SP 150" span, 144" length flying on a DA 200cc with stock exhaust.
Bob
52% 2nd Day out 2 years ago
Bob
52% 2nd Day out 2 years ago
Nice 3 point at the end - you are landing on the proverbial dime with that airplane!
01-10-2014, 03:48 PM
#100
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Here is another 3 year old video messing around at the lake with my 55% Extra 260 with a span of 164", and a DA 200cc for power, keep in mind that most airplanes this size are running something like a 3W 342cc or larger power plant.
http://vimeo.com/12393389
Bob
http://vimeo.com/12393389
Bob
Only thing I have remotely close to this is my (almost) 55# 3W Ultimate Bipe. Powered by a 3W 160 4 Cylinder, it's a tad heavy, but has great presence (and sound) in the air!
It also lands rather heavy though as you'll see...
http://youtu.be/EYnSDswdtr0