Bloop Questions & Answers

This is a listing of selected questions that I have been asked about the Blooop and motorfloaters in general, along with my answers. I do appreciate comments, new questions, and corrections. Be sure to read the website first and then ask the question in terms of that, if it applies, otherwise I won't know what you have already seen. My e-mail address is "m--sandlin" followed by "@sbcglobal.net ".

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May 2, 2012 "...my questions are not resolved by any thing I've read on your web site or the discussion group stuff. Specically concerning pilot weights wing loadings and maximun/gross numbers. I ask because I am 6 foot 5; acordingly weighted, approximately 275 plus not fat but big!!...have you investigated this region of bloops potential?"
Answer: Down through the years the heavy pilot question keeps coming back. I don't have any new answers. To get the benefits of light wing loading for a pilot 100 pounds heavier than average the wing must be made bigger, and I doubt that this will be done by anyone who is not himself heavy. If there were a two place airchair or motorfloater, a heavy pilot might fly that, as a heavy hang glider pilot will sometimes fly a wing built for two place hang gliding.

April 19, 2012 "...Ultralight airplane engine and reduction drive ... to see what you think of this type of engine for the bloop1..."
Answer: I'm not an expert on engines, so I don't comment on other people's choices except in general terms. I use a 25 horsepower paramotor engine, an "off the shelf" unit, complete with reduction drive and propeller, developed to work well at the speeds at which I fly. Modern paramotor engines typically have efficient mufflers, good noise reduction, effective vibration isolation, and easy pull rope starting. They are light in weight, compact, and have low fuel consumption. A paramotor engine has an absolute weight limit because the paramotor pilot has to be able to pick it up and run with it, and they have a market big enough to support engine development, so this is where the high quality small airplane engines are found.
I'm trying to push the "reset button" for small, light airplanes and engines. The Bloop is intended to be like a flying motor scooter, not a speed machine. Typical "ultralight" airplane engines, as used by light sport airplanes, are big and heavy, not much smaller than about 40 horsepower, too much for me.

"Have you tried using the Bloop as a self launching glider and doing some soaring after launching? If not, would the changes to the design be too great to consider building such an airplane?"
I have flown the Bloop as a motor glider, and it does what you would expect. It climbs well in lift but does not glide well between thermals. So, a motorfloater can do its climbing in thermals and then cruise under moderate power. This is not the traditional motor glider practice, but it is a good way for a motorfloater to minimize fuel consumption and engine usage. On a mid day flight with a small engine, thermalling could become the obvious thing to do, the fast and easy way to get altitude.

"Is the new higher [lift] airfoil a published design or is it something that you drew up yourself?"
The airfoil I am now constructing on the Bloop2 motorfloater is a variation of the one I used on the Bug and Goat airchairs, my own version of a double surface, flex wing, hang glider airfoil. This is not a formally defined or tested airfoil as far as I know. I like this hang glider type of airfoil because it has been demonstrated to work well at my airspeeds, has undergone many generations of development and testing, and is well suited for adaptation to the rough structure of my quickly built tube and cable wings.
Why has so little analytical attention been given to hang glider airfoils? This is a mystery to me, considering that this is the practical and proven airfoil of choice for hundreds of flights made every day.

March 24, 2012 "I am living in a... hilly part of France with hardly any space to build a proper airstrip. Mine is situated on top of a hill and has the size and appearance (from the air) of a small World War -2 aircraft carrier, which... cannot ...... be pointed into the wind. Missing the "deck" (treshold) can give big trouble. So, for safe sidewind landings... I think...ailerons "

Answer: I'm glad you like the Bloop, and I think something like it should be fun to fly from a little hilltop airstrip. I suppose you can put ailerons on a Bloop type airplane and use them to slip, but that is not really the solution to a short runway. I would probably add airbrakes or a drogue chute for regular tight landings because for the same level of complexity those would be more effective in allowing steep descent without airspeed gain, and in reducing ground roll. Also, unlike slipping, you can use airbrakes all the way down the runway, along with the ground brake. I am not impressed with the energy loss accomplished by slipping, not after flying with effective high drag devices.
I think all of this applies to cross winds as well as otherwise.
Two axis planes are generally held to be limited to small cross winds only, but I suspect that that is a landing gear design problem rather than an inherent limitation. With my "nose low" ground roll, I have not yet encountered any cross wind limits.

Feb. 29, 2012 "What are the expected cruise/stall speeds for the Bloop 2?"

Answer: I have no estimated numbers, but I'll take some measurements when I get flying, as I did with Bloop1. For a motorfloater the stall speed will depend a lot on the weight of the pilot, of course, so that will be quoted, also.

FAR Part 103 requires that a motorized ultralight must be able to fly at less than about 28 mph. (stall speed not to exceed 24 knots), which implies a kind of pilot weight limit. Presumably, an ultralight with an average weight pilot and a marginally fast stall speed cannot legally be flown as an ultralight by a heavier pilot because the stall speed will be excessively fast. The Bloop stall speed should be quite slow, well below the limit, with an average pilot.

Response recieved: "Part 103.1(4) “Has a power-off stall speed which does not exceed 24 knots calibrated airspeed.” Advisory Circular AC 103-7 # 21, further defines the requirement to calculated (or demonstrated) with a pilot wt. of 170 lbs and a full tank of fuel (5 gal @ 6 lbs/gal)."

My response: This answers the question. There is no implied weight limit, the stall speed limit refers to a specified loaded condition. I now see that Part 103 does not stand alone, it must be taken together with whatever Advisory Circulars have been issued as clarifications or definitions. This also provides a useful design model for an average piolt weight. (However, since my gas tank only holds 2.5 gallons, I presume my pilot can be 15 pounds heavier...?)

"The idea of $5k for a motor seems a little (no a lot) steep...something suitable out there that could be modified for a lot less.

A lightweight flat twin two stroke [engine] might be a viable candidate especially for low vibration/noise levels."

I want to work on airframes, not engines, so I look only at "off the shelf" power packs that don't require any modifications or development. There might be paramotors sitting in closets, maybe not the latest models, that would be inexpensive, and any popular paramotor system should be able to power a motorfloater.

"... is there any way I could get to fly a Bloop 1?"

Not even I can fly a Bloop1 since I tore it down and started the re-work to the Bloop2 version. I really miss my open air local flying and I hope that the next time I build a new airplane I can keep the old one operating.

At the time I grounded the Bloop the underside fabric of the upper wing had become weak and was not airworthy, in my judgment. The upper surface wing fabric on both the upper and lower wings was fine, even though it had been outside for a year and a half, because it was well coated with protective silvering (aluminum powder in dope). There was no protection on the lower surfaces, since those were expected to be in the shade, and this worked well enough on the lower wing, but not on the upper wing, which was a surprise to me. I think the reflected sunlight, from the ground or lower wing, caused the lower surface fabric of the upper wing to deteriorate.
From now on I will apply some protective silvering to lower wing surfaces as well as upper surfaces, which is more like a conventional fabric covering job anyway.

Jan. 27, 2012 " ...wonder if adding a small wheel on the front skid to prevent wear or do you see a wear bar is better. Also how much flight time have you put in on this airframe design? I have been reading about the engine and wonder how are you finding it; would you change it out if you could now.
I am interested in building this since it is built around a motor and I am not a glider pilot and we do not have any great hills to glide from. "

Answer: On the Bloop Page I describe why I use a glider type landing gear, basically for safe landings in strong winds, an important issue at light wing loadings. The nose skid is reliable, fun to use, light, and simple. There may be a conventional wheel system that will work as well and not be limited to light winds, but I haven't seen it yet.

As a motorfloater I flew the Bloop1 about fifteen hours, mostly making brief flights. As a glider it did a lot of rough flights but didn't get much airtime.

The simple paramotor engine has worked well and was easy to put on the plane. An "off the shelf", integrated, flight proven, and available power pack is good for me, it allows me to concentrate my design efforts on the airframe. We might choose to use additional engine instrumentation relative to the paramotors (which is pretty basic or almost absent), or maybe we'll learn to do it their way, we'll see how it goes.
Any good paramotor engine setup should work well on the Bloop. If I were getting a new engine, I might get one of the 4 stroke paramotor engines of about the same power as I have now, just to try it out. The 4 stroke would be heavier for a given thrust, but it's supposed to be quieter, more reliable, and to use less fuel.

The great benefit of a motor plane is that it can fly out in the great flat lands where glider launches are hard to come by. Gliders appeal to me and a limited few, but most pilots want motors.

It's best when custom airplane builders build because they want to, not just to get a particular airplane. "Buy and Fly" is the best plan except for those who want to create or experiment. I would like to see something like a commercial Bloop, but I have no plans to be involved in that. The Bloop has a conventional airframe and controls but a radically light wing loading, and unfortunately I know of nothing like it that can be purchased.

I don't know of any home building kit for a motorfloater.

The "Bill of Materials Kit" for an ultralight aircraft is possible but has not been attempted yet. Someone has to list all the required materials on a spreadsheet and organize them into three or four purchase lists addressed to particular retail vendors. Then builders can download those lists and easily order almost all of the materials and parts they need, and have them delivered by parcel truck, without the need for a kit supplier. Building support would come from the Web, from forums and from a website dedicated to the building of that aircraft.

Feb. 5, 2012 "Do you see the Bloop2 being significantly different from Bloop1?"

Answer: The Bloop2 will continue along the path of the Bloop1. It will be is a motorfloater intended to explore slow flight with a simple airframe and controls, a small engine, and good pilot crash protection.
Bloop2 will be generally similar to Bloop1, but will have a higher lift airfoil and is intended to fly slower, and hopefully it will have even more forgiving slow flight characteristics. A primary goal is to be able to hold the stick full back and just parachute down, with no stall or nose dropping. There will also be mechanical and structural differences (one central rudder instead of the two rudders, perhaps a simplified motor mount, etc.).

Feb. 6, 2012

"...specific... areas ... that you ..(could be) altering in the next generation of your design...

layout of the wing-to-fuselage sides join, The joining of the nose section to the wing leading edges by eyebolts has proven to be effective and convenient, and will be continued. Usually I avoid changing things that work well unless I'm pursuing some major design goal or addressing a specific problem that arose in flight operation.

motor placement/mount, Again, this has worked well and I have no reason to change it, except perhaps to simplify the original design. One of the main things I learned from motorizing the Pig (Bloop1) was the acceptable diameter of the propeller (1.3 meters), and this will be part of the Bloop2 design.

pilot hight location relative to the planes of lift, The pilot should sit high enough to be protected in a crash (and to feel confident of that protection), but he should be low enough to get his feet on the ground so as to be able to push up the nose for takeoff or to turn the plane around (in place) on the runway. The curerent position works for me.

modified airfoil, Yes, a higher lift airfoil is planned, to get more of the benefits of slow flight: the experience of open air flying, comfort, low fuel consumption, crash safety, and the oportunity to make gross low airspeed mistakes without severe penalties.

improved control surfaces response and resultant stick/pedal loading...No, there's not much call for change here, control loads are not much of an issue at low speeds. A rudder in the propwash is planned to improve the very low speed ground control, that's all.

body section change from your proven box design (spray foam/aluminum hybrid, different fuselage skin approach). The nose section structure is not a complete braced truss (the top is not cross braced), and thus is not very stiff in twisting. This was okay for airchairs but the motorfloater has a much deeper nose section with the skid lower down, so the twisting due to ground contact was excessive and required the installation of an extra set of forward sweep cables. I like this setup and will retain it for Bloop2, but certainly other structures are possible.

...what other design changes/challenges have you arrived at? Transportability and quick dissassembly for storage are worthy goals, but slow flight comes first, then we will see.

"...from a ...design perspective is surviving a slow-speed emergency water landing, without irrecoverable damage to the aircraft, feasible?" Let's call this a crash, in water or elsewhere. The first rule in a crash situation is: protect yourself, don't worry about the aircraft! Destroy the plane and walk away with a smile on your face, dreaming about your next magnificent flying machine.
As for water, be careful. Deep water is one of the two big dangers (power lines are the other).

Do you think that slow motor floaters design challenges could translate well to r/c scales? It would not be too difficult to make a small r/c
scale model aircraft modeled after yours, and to use that scale model if it proved functional, to test extreme flight characteristics of the
current Bloop, and test modifications. I have read online that designs do generally translate from larger scale to smaller scale.
Large scale remote control fliers could do all kinds of good experimental work, they could perform all sorts of tests for low speed aircraft. The results will not be rigorous but they can suggest what might be done, especially with video results to show on the web.

Feb. 14, 2012 "... i am concerned about transistioning to an aircraft without ailerons. How different is it to fly when your stick only goes forward and back."

Answer: In theory, pilot conversion to a two axis rudder/elevator plane should be easy. You just scoot around on the airstrip doing hops and turns, knowing that all the control inputs will be the same in the air as on the ground, and when everything seems familiar, off you go. In reality, there may be a moment of, shall we say, distress, before that first turn in the air, when your previous training calls for some side stick action, but it's not gonna happen. This is when you take a deep breath and recite the mantra: "steer with your feet", and when you finally do this, the flight continues normally and all is well. Of course, you can practice steering with your feet in almost any airplane just by not using the ailerons. Turning this way may be slow and strange feeling in most airplanes, but it will demonstrate the basic method.

Feb. 23, 2012 "...the Hirth F-33 engine is the one for me [mention of local services, 1000 hours to overhaul]"

This should work, since it is well established as a paramotor and trike engine, and has support and service close at hand. It's a little more powerful than mine, and so will have a faster climb.

The engine I chose is also a paramotor setup, but it has a tuned exhaust for extra power and noise suppression,
a compression relief for easy rope pull starts (so I don't use an electric starter), a bulkhead mount (not requiring a special engine mount to get from the horizontal to the vertical mount), and it is a smaller engine so it will use less fuel, make less noise and will vibrate less, and allows me to fly at a lower wing loading.

Paramotor engines can have some drawbacks. The extensive inlet and exhaust systems are installed across the wind and may not be practical to clock forward to a less draggy position. They may not have a good place to put the EGT (exhaust gas temperature) sensor since they might not usually use them (they may use CHT, cylinder head temperature, if anything).

"drawing B1W17 has a part called, Strutt Fitting which calls for a piece of alumimun, 1/8 x 1/2 X 2-1/4 IN long. Now throughout your drawings the brackets and such have been 1/8th IN thick. So does this part require 1/2 thick stock or were the measurements transposed..."

Answer: The dimensions are correct and the drawing is clear, I think. There is a standard given in the drawings for the order of the dimensions for tubing, but I don't know of any formal standard for bar stock.

"...to build your... Bloop... how many hours do you think that I need?...what will be its probable cost without the engine and prop...?"

Answer: The cost of material will vary depending on location and builder decisions. Here in San Diego, I might pay $3k to $4k for airframe and covering materials, $5k for a new engine & prop, $800 for a new hand deployed parachute. A rocket deployed parachute (BRS type) might cost $3k if desired (the biggest cost variable is the emergency parachute, and a fancy fabric covering job might be next in cost variation after that). These are quick guesses, anybody with a spreadsheet and a willingness to look up the latest prices could do a better cost estimate than me.

The time needed is an unknown. I think I could build a motorfloater in less than a year without too much strain. I'd like to design airplanes and gliders that can be built in the cold season and flown in the next warm weather.
Hi-I have found your motorfloater "bloop" to be quite endearing,reminding me of early Farman brothers or voison pioneer types! my questions are not resolved by any thing I've read on your web site or the discussion group stuff. Specically concerning pilot weights wing loadings and maximun/gross numbers. I ask because I am 6 foot 5; acordingly weighted, approximately 275 plus not fat but big!! biplanes are great for the load ability within the span limitations plus the simple engineering strength - so how far have you investigated this region of bloops potential? the limitations of part 103 are painful to me because of the faa's reliance on the 'standard" pilot!!

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