Flight B/C

[pumptato-cat]

I'm also a bit confused as to what you mean with the "post with adjustable height on each side." If you mean leading and trailing edge, I don't see how that'd change radius. If you mean both sides of the tailboom... Well your adjustments would be pretty sensitive, yeah? I think I might just be misunderstanding things.

I meant something similar to a wingpost where instead of two posts front and back you could have one or two on each side of the tailboom, with the HS glued only to those posts. Adjusting them up/down on one side but not the other could change the tilt, though You'd have to probably change the rib spacing so that the posts have something to stick to. This is just something I theorized last season that I was thinking about applying this season but I don't think it'll be necessary since this year's FF design actually features a tailboom instead of the HS just being on the motor stick.

Also, I think I understand what you mean by this; but wouldn't it be rather difficult to adjust precisely? If I'm interpreting this correctly, wouldn't the two posts be attached to the trailing/leading edge with barely 1/8" in between? I like the idea very much but I'm worried about how well it'd hold up or the precision of adjustments.

[pumptato-cat]

There's a Flight thread you can use in these forums under "Build Events." Maybe move future discussion there?

2023 was released October-November-ish if I recall correctly. You could always email Dave Ziegler and ask. He's very nice!

[bjt4888]

Any suggestions for torque meters?

I'm going to attempt more solo flying this year as my potential partners will likely be building their own plane and following their own schedule. Additionally, I will not have a partner until after tryouts in October, and I need to get a plane flying before then to do well in tryouts.

The torque meter I used last year was from Freedom Flight, and even though it was expensive I bought it because I trusted the company. However, the meter wasn't the most accurate and would slip around a lot (could be a construction error but I'm not sure). Anyhow, I'm looking for a good torque meter to assist me this season. I've seen people in competitions with torque meters that you could step on. Those seem cool, what company are they from? Should I be buying them or is there a better alternative? My main problem is that I can't get the torque meter to stay put when I put a fully stretched rubber band on it. It was too far for any part of my body to reach it and I didn't have my partner or any tools to hold it to the gym floor. I've seen suggestions like velcroing the torque meter to a table, but I don't want to bring a table with me to school to test every day.

The one that you can step on seems like the perfect one for me this year, as a full stretch should only be 5.25 feet (75% of last year because you have 75% the mass), which is shoulder height for me. Any thoughts/recommendations?

Astro

Astro,

Sorry to not reply sooner. As Cat mentioned, there is a quick fix for the FF torque meter from last year. The small loop in the torsion wire that the rear pivot bolt goes into is a little too big on the meters we got from them last year. Remove the bolt and the torsion wire and squeeze the loop about 1mm smaller so that the bolt has to "thread" into the loop. Once you have done this, the meter needle will stay put once you set it initially to the zero point (bend the pointer wire a little to "zero" it).

The J&H torque meter is another possibility. It is a kit, but is extremely simple to assemble. I put together twelve of them in about five hour this summer to use for the SO National Summer Institute/Workshop for Flight (so, less than 1/2 hour to build each one and no soldering is needed).

Look at the NFFS video demonstration for winding a typical 2023-24 rubber motor here: https://www.youtube.com/watch?v=_MCNDiLF06I you'll see my homemade torque meter. It's basically this meter, but with the frame made out of wood: https://www.indoorspecialties.com/artic ... 0Meter.pdf

Note the super simple method of anchoring to the table; a bent coat hanger. Although this looks crude, it is very handy as the coat hanger can be rebent to fit any table edge shape and can also be bent to hook to any piece of sturdy material you can find in the competition gym (if they don't supply a table).

A typical motor this year will be about 11-12" and can be stretched comfortably to 6 or 7 ft to get maximum turns.

Keep asking good questions, you're doing great!

Brian T

[bjt4888]

ykm849,
You mentioned that you bought an FF kit--was this the 2023 one?
I bet you'll do much better than 11 seconds with a kit! Bjt4888 and Coach Chuck both give amazing advice--if you listen to what they say and put it into practice you'll improve quickly.
Astro made a lot of good points. It's very impressive that you were able to scratch-build a plane. I've only scratch-built two, and it was very difficult... I had a lot of help too! You're doing great, and I bet with some help and the forums you'll be pretty competitive

Astro,
you don't necessarily need a laser cutter to design balsa ribs. They can be made by using templates and hand-cutting--a lot more accurate than it sounds. I also despised the fixed stab(dreaded repairing it to change the stab by half a degree only to see that it was a good 1 degree off from my intended target! Awful) but apparently you can just bend the balsa and it holds position. On my pennyplane I glued the tailboom and then just bent it with my fingers whenever I wanted to change circle size. I'm also a bit confused as to what you mean with the "post with adjustable height on each side." If you mean leading and trailing edge, I don't see how that'd change radius. If you mean both sides of the tailboom... Well your adjustments would be pretty sensitive, yeah? I think I might just be misunderstanding things.

bjt4888,
What do you think flight times will max out at this year? 1.5g rubber sounds pretty tough, especially because minimum weight is still 8g. I've heard rumors of max times being 3:30.

Cat,

We also don't like posts on the stabilizer; too easy to get out of adjustment. As the longer fuselage allowed by this year's rules pretty much ensures that you can have a tailboom glued as a separate part from the fuselage, as Cat mentions, this allows pretty simple and secure changes in tailboom offset.

As for approximate flight times for this year, you can get a pretty good estimate by first knowing your best typical flight average propeller revolutions per second (RPS) from last year. And then use the rubber motor max turns equation (on the NFFS website already linked in this forum). I did this type of calculation in my demonstration flight for the "Super Simple Div B Airplane flying video" on the NFFS website. Look in the description for this video and you'll see all the specs for my winding and my calculated RPS. The RPS we got on the stock FF kit (with stock propeller with pitch adjusted) last year after extensive testing and improving of CG, decalage, rubber density and prop pitch, was 7.0 RPS (for 24 ft flights of about 3:10-3:15; best flights with a flaring prop were 3:30 at 22 ft last year). So, an 11" 1.49g motor with two black rubber o-rings is .0622 g/in (approx) and will take about 1,300 turns at about 88% breaking turns. A good trim might allow 150 backoff turns and 150 turns remaining for 25 ft climb height flight. This would mean 1,000 turns are used to fly the airplane. Divide this by an RPS of 7 would give a flight of 2:22. Even better trim and a flaring propeller would get the flight closer to 3:00.

Good questions. Keep them coming!

Brian T

[coachchuckaahs]

Yup I got to see the new FreedomFlightModels Div C plane which Mr. Zeigler sent me a pic of it in an email response to me, and it looks awesome! I did flight last year but I built one out of scratch from some spare balsa sticks I found in a thrown cardboard box. I curved them by wetting them and pressing them against a hot glass and built the structure of a typical flight model wing ribs. Even though I spent a lot of time trying to build my first plane it only flew for 11 seconds because it weighed almost 14 grams since I built a propellor out of some hardened construction paper and thin cardboard without knowing how to pitch the propellor , so thats why im ordering a kit this year in hopes it can perform better results, which im sure it will C:

11 seconds is pretty impressive considering that many homemade planes don't fly at all. Nearly everyone in Science Olympiad will find better success with a kit than with a homemade plane. The only exception is with experienced flyers who have squeezed nearly every ounce of optimization from kit planes and could fly over around 3:15 last year, or the top few flight teams in the country. Even so, designing and building a plane requires an entirely different skillset then the one polished by Scioly flyers.

We need not worry about wing shape/size, aspect ratios, cambering, and other things that the kit makers set for us. Designing a new plane also requires CAD skills and access to a laser cutter for the balsa ribs. I'd imagine that most people with well-built homemade designs get help from others (probably coaches) and could probably fly well in F1D. The best flyer at my school besides me actually does homemade design, but even with years of experience (her brother had self-designed planes before her) the plane she built only went around 90 seconds last year (didn't take full advantage of the box diagonal, no cambering, and was too fast and climbed too high). And the planes developed by kit makers like J&H and FreedomFlight are so good that there's no chance your homemade designs are better unless you have years of experience and understand flight mechanics beyond what is required for success in Scioly. In short, use a kit, do not make the mistake of designing your own plane as the vast majority of people lack the skillset required to make one, as opposed to the kit makers, who do.

If you ever want to put your own twist on your plane, stick to basic modifications to kit planes. Optimizing small things one at a time from a well-built plane is much better than building an entire one from scratch. For example, one thing I didn't like last year about the FF plane was that you had to take off the horizontal stabilizer and reglue it every time you wanted to adjust it. Putting it on a post with adjustable height on each side would have been more convenient to set circle size.

I can tell that you have a particular knack for planes, being able to scrap a decent one by homemade standards (the way you made the ribs is impressive given the lack of a laser cutter). Translate that to a knack for adjusting/trimming your planes and you'll be competitive in no time

Coaches - please correct me if anything I said was misleading or wrong. This is my general perception on making your own plane and I want to change it if it isn't accurate.

Astro

I have been gone pylon racing and have not kept up.

A few points on building without a kit:
1. You do NOT need CAD skills or a laser cutter. We have used neither. We lay out our design with graph paper or any online drawing program (we use Microsoft Publisher, actually!) Cutting ribs we use a template from hardware store aluminum flashing (draw a template in Publisher, print and glue (3M77) to the metal, cut metal with scissors) or 1/8" plastic. Alternatively we have cut a form from 2x4 with bandsaw, and wet-formed a sheet of 1/16" wood to shape, then slice ribs from that curved sheet with Master Airscrew balsa stripper. While FFM has a different airfoil, most indoor planes including F1D have simple circular airfoil (circular arc).

2. A basic understanding of plane layout and shape is needed, but there are plenty of plans online that you can copy and update. We started with Bill Gowen's Carbon Penny and/or Finney for ideas, and adapted to current rules

3. We started with Ikara props, but quickly graduated to making your own. But you can scratch build and use a commercial prop.

4. Coach Brian has put together a video build of a "super simple" SO plane, built to Div B rules this year, which can do 2 minutes with a flat airfoil (no curved ribs), based on Chuck Markos design. This can be easily adapted to Div C, and gets you in the air fast (1 hour build easily). You can get that video from the NFFS web site, https://www.freeflight.org/science-olympiad/. Be sure to read the description (downloadable file or view from YouTube)

5. While there is science involved with design, if you copy the general layouts, scaled to the rules, of past planes in plans, you will do just fine without any diabolical knowledge.

I agree that kits are an easy starting point. We never did a kit, but the first year we flew we built 12 planes as we learned new things. Coach Brian on these forums was an incredible help, and in the end we went from 20 seconds to 2:50 and came in 7th at Nationals. It is more of a challenge, but very rewarding.

The super simple plane is a great way to get your feet wet self-building, and will fly very well with minimal investment and time.

Coach Chuck

[coachchuckaahs]

Any suggestions for torque meters?

I'm going to attempt more solo flying this year as my potential partners will likely be building their own plane and following their own schedule. Additionally, I will not have a partner until after tryouts in October, and I need to get a plane flying before then to do well in tryouts.

The torque meter I used last year was from Freedom Flight, and even though it was expensive I bought it because I trusted the company. However, the meter wasn't the most accurate and would slip around a lot (could be a construction error but I'm not sure). Anyhow, I'm looking for a good torque meter to assist me this season. I've seen people in competitions with torque meters that you could step on. Those seem cool, what company are they from? Should I be buying them or is there a better alternative? My main problem is that I can't get the torque meter to stay put when I put a fully stretched rubber band on it. It was too far for any part of my body to reach it and I didn't have my partner or any tools to hold it to the gym floor. I've seen suggestions like velcroing the torque meter to a table, but I don't want to bring a table with me to school to test every day.

The one that you can step on seems like the perfect one for me this year, as a full stretch should only be 5.25 feet (75% of last year because you have 75% the mass), which is shoulder height for me. Any thoughts/recommendations?

Astro

There have been several comments on torque meters here.

You can do a solo flight, but it is imperative to connect your torque meter to something. Coach Brian pointed out they use a coat hanger to strap to a table. We bring our own folding table and have velcro permanently on the table. Most SO-commercial TM's can be clamped to the table with a cheap ratcheting clamp from Harbor Freight or home depot. Most events will have a table or two the students can use, but you cannot count on that. You can clamp to just about anything. Bleachers, chair, rail, door, something.

You really do not want to try to hold both the TM and the winder. Not only must you be a contortionist, you will have a hard time loading the TM only in the axial direction. Side-loading the hook and lead to false results or damage the hook.

The simple TM's available from FFM, J&H, and Laser Cut Planes are all suitable. They may vary in their accuracy, but they should be repeatable. The Laser Cut one is not calibrated at all (the numbers do not correspond to real world values), but it would work just fine. It comes with a clamp for $12!

Other than that, you can build a digital one form my Thingiverse plans at https://www.thingiverse.com/thing:4241753

You can make a simple digital TM with just a pivot and arm, plus an existing digital scale. If your arm is 1" long, set the scale in oz and read inch-ounces directly. If the arm is 2.834" long, set the scale in grams and read oz-in X 10.

Coach Brian is working on a "super simple" torque meter you can build from hardware store parts (Paint stir sticks, wire) for very little cost. But the TM kits out there at our regular suppliers are very suitable and may be simpler because the parts are all cut for you.

Coach Chuck

[coachchuckaahs]

I'm also a bit confused as to what you mean with the "post with adjustable height on each side." If you mean leading and trailing edge, I don't see how that'd change radius. If you mean both sides of the tailboom... Well your adjustments would be pretty sensitive, yeah? I think I might just be misunderstanding things.

I meant something similar to a wingpost where instead of two posts front and back you could have one or two on each side of the tailboom, with the HS glued only to those posts. Adjusting them up/down on one side but not the other could change the tilt, though You'd have to probably change the rib spacing so that the posts have something to stick to. This is just something I theorized last season that I was thinking about applying this season but I don't think it'll be necessary since this year's FF design actually features a tailboom instead of the HS just being on the motor stick.

We have adjustable stab on most of ours, but only adjustable in incidence. This takes one post at the front and one at the rear. We really mostly leave this at 0 degrees, so gluing on should not be a problem. We adjust our decalage (different between the wing angle and the stab angle) by changing the wing incidence. The one advantage of the posts for the tail is that we can remove it for long-term storage. We however keep our plane assembled during the season. If you must travel a long distance, breakdown (and good records of your settings) is important.

For the wing we do use wing posts attached to the motorstick, with a tissue tube or some 1/8" OD R/C antenna tube attached to the wing. This makes easy incidence adjustments, but makes wing position adjustment (front to back) harder than the saddles many kits use. We have to cut the posts off carefully and move them on the MS. Building light you can move the CG with ballast rather than moving the wing.

I would not try a 4-post arrangement for tail tilt. I don't think it would hold well. Rather, slightly dampen the tailboom and twist for tail tilt, bend for rudder offset, then dry with a heat gun or let dry overnight (but would have to fixture i tin the new position)

Coach Chuck

[coachchuckaahs]

I received a PM with some questions that should be asked here so that all may benefit from my answers.

One part of the question was:

I read in your guide the portion where you talk about how maximizing propeller diameter is more efficient, and I was curious because I'm seeing that the standard prop diameter used in Brian's model and the Freedom Flight kits are the 9.5 inch Ikara props. I've seen larger 12 inch Ikara props available that I believe fit within the rules dimensions, and I was wondering if they would be a better alternative.

In years past, the prop size has been limited to various sizes, with the 9.5" (24cm) being common. This year it is not. The 24cm may be the largest you can fit in C division due to box dimensions, especially if the plane is diagonal in the box. But in B div, a 12" (30.5cm) prop should easily fit (we used 12" last year). So the available commercial props are based on a history of rules sequences, and is by no means optimized for this year. Keep in mind if you go bigger on the prop you will need to go bigger (higher g/inch, shorter 1.5g loop) on the rubber as well. There is no limit to prop size this year except the box, so be sure your proposed prop will fit in your box, on the plane.

Larger props will load more torque on the plane, and so could increase banking in the turn. This can be countered with more wing offset (left side longer) or some wash-in. We did not need either last year.

Limited Penny Plane has 12" props, and an 18" wingspan (sorry for all English units, but that is how that event is specified), and it works fine.

Coach Chuck

[Astronomyguy]

Thanks for all the replies! It's only the start of the season and I've already learned so much:

In regards to adjusting the horizontal stabilizer, I'll definitely try wetting and bending/twisting the balsa for adjustments now that we have a tailboom on the Freedom Flight kit instead of the HS being attached directly to the motor stick. Should be more of an option this year with the tailboom and will definitely be less painful than taking off and regluing the whole thing. Question - does a low power hair dryer do the trick with drying balsa? I have some at home that barely output any air but that could be a benefit as too much air could damage the mylar.

Torque meters - I'll try fixing up my torque meter from last year before buying a new one, I'll see how it goes. I might bring a table to tournaments (thought that probably won't be necessary with a partner to hold the meter) but not to school, as I walk home from school and carrying the plane and my toolbox is already a stress in addition to my backpack and instrument. There's usually a lone desk in the gym where I practice; I should be able to clamp the torque meter to that when I fly.

Designing your own plane - My views have changed significantly on designing your own plane now that I've learned that you don't need many of the skills I thought you would need to design a plane from scratch. I also didn't know that most people just used scaled versions of other planes like the Finny and Carbon Penny for non-kit planes, which would make things significantly easier. I might even build a plane of my own later on if it's worth the effort. Relieved to hear that getting all the parts isn't as daunting as I thought it would be.

How much time do the Scioly-scaled Penny and Finny planes usually gain on the Freedom Flight models year after year? My current knowledge is that they aren't a significant improvement because the FF plane is already a good model but I'm trying to weigh whether building one of those would be worth the performance increase or if most people just do it to save money.

Making your own prop - I've heard that a well shaped balsa prop outperforms any other material - how hard is it to make them? My current plan is to start with the Ikara props that come with the FF kit, then to make a flaring prop (designs and steps in the 2015 forum?), then to move to balsa.

First few practices - This year I'm trying to make my practicing more methodical rather than just adjusting things until the time goes up. My current plan is to trim using glide tests first, then going to medium torque to test climb before going to higher torque to test climax and descent. Is this a good plan or is there something else I should be doing?

Thanks for all the help,
Astro

[bjt4888]

Thanks for all the replies! It's only the start of the season and I've already learned so much:

In regards to adjusting the horizontal stabilizer, I'll definitely try wetting and bending/twisting the balsa for adjustments now that we have a tailboom on the Freedom Flight kit instead of the HS being attached directly to the motor stick. Should be more of an option this year with the tailboom and will definitely be less painful than taking off and regluing the whole thing. Question - does a low power hair dryer do the trick with drying balsa? I have some at home that barely output any air but that could be a benefit as too much air could damage the mylar.

Torque meters - I'll try fixing up my torque meter from last year before buying a new one, I'll see how it goes. I might bring a table to tournaments (thought that probably won't be necessary with a partner to hold the meter) but not to school, as I walk home from school and carrying the plane and my toolbox is already a stress in addition to my backpack and instrument. There's usually a lone desk in the gym where I practice; I should be able to clamp the torque meter to that when I fly.

Designing your own plane - My views have changed significantly on designing your own plane now that I've learned that you don't need many of the skills I thought you would need to design a plane from scratch. I also didn't know that most people just used scaled versions of other planes like the Finny and Carbon Penny for non-kit planes, which would make things significantly easier. I might even build a plane of my own later on if it's worth the effort. Relieved to hear that getting all the parts isn't as daunting as I thought it would be.

How much time do the Scioly-scaled Penny and Finny planes usually gain on the Freedom Flight models year after year? My current knowledge is that they aren't a significant improvement because the FF plane is already a good model but I'm trying to weigh whether building one of those would be worth the performance increase or if most people just do it to save money.

Making your own prop - I've heard that a well shaped balsa prop outperforms any other material - how hard is it to make them? My current plan is to start with the Ikara props that come with the FF kit, then to make a flaring prop (designs and steps in the 2015 forum?), then to move to balsa.

First few practices - This year I'm trying to make my practicing more methodical rather than just adjusting things until the time goes up. My current plan is to trim using glide tests first, then going to medium torque to test climb before going to higher torque to test climax and descent. Is this a good plan or is there something else I should be doing?

Thanks for all the help,
Astro

Astro,

Good questions!

A low power hair dryer would probably work for the tail boom adjustment, it will just take longer to dry the boom. Although the wet and bend method is quite usable, we actually take a different approach to adjusting the tailboom. We don't overdo the glue when attaching the tailboom to the fuselage so that we can partially crack the joint by sliding a blade between TB and Fuse (while pinching the TB/Fuse joint tightly so that it doesn't move. Then we slide a thin tapered shim of 1/32" wood (tapered to very thin) to change tailboom offset (and thereby change rudder angle). For change in stab tilt, we do a similar slight cracking of one side of the TB leading edge and trailing edge joints, then verify by eyeballing till you get the tilt change you desire and touch the cracks with one drop of CA. This works best with carbon rod TE and LE. We usually only need to make one adjustment of either of these settings.

Gain from a scaled Finny would be very small vs. a Freedom Flight or J&H kit. Unless you have a lot of gym time (with blowers off), or if you just want to play with designs for fun, your time would be better served by refining trim and building custom flaring propellers for one of the good kits. I'll give you a for example. I coached 14 HS students last year (and 4 MS students) and one of the HS students flew a completely stock FF kit. The FF kit, with very good trim, flew 3:05-3:10 at 23 ft climb height. Our own design , flew 3:30 at this same 23 ft climb height (this is Division C, not B). At the height flown at Nationals (34 ft) it could do quite a bit more time. I posted a video of it flying an early season 3:25 at 23 ft last year. Most, if not all of the difference in time was due to the custom flaring propeller (this is not a guess, we proved it by testing). Even the modified Ikara "Flaring" per my pictures in the 2015 Wright Stuff Scioly.org thread will add 10-15 seconds over the Ikara 24 cm symmetrical prop.

See the first document in both the "Building" and the "Flying" tab of the NFFS Science Olympiad Student Resources for more info on a trimming method to get these type of results https://www.freeflight.org/science-olym ... resources/. Get all you can out of the 24 cm symmetrical Ikara by testing per the notes in this doc (including pitch changes and corresponding rubber tests) before moving to the flaring prop.

In this same NFFS webpage is an "Advanced Topics" tab that has a demo of custom balsa prop building. The prop being demonstrated is for a small AMA airplane, but the techniques are the same to build one for SO. It's not hard. My MS students built Bill Gowen style propellers for their airplanes last year.

Yes, the success in the event is 80% methodical flying practice, with careful logging of data, and 20% design. Read the documents in the NFFS website. They are new for 2023-24 (including a winding demonstration video for a 2023-24 typical rubber motor). I'm sure you are referring to launch torque when you mention "medium" and "high". You'll see in the NFFS trim document the progression of test flights that we recommend. Glide tests are an ok way to start testing. We almost never do them though as we always start with the kit of SSM calculator recommended CG and trim settings and then modify in small increments during testing. You'll see that the FF kit this year recommends a CG "range". You could start with the CG in the middle of the range if using this kit.

Have fun!

Brian T