Flight B/C

[coachchuckaahs]

Did you go to your first event, and find that your box was oversized, or your plane did not fit fully into your box?

Fear not, you are not looking at a complete rebuild!

Coach Brian has put together a video on trimming a few (or more) mm from your wing span without destroying your plane. Also some tips on making a nice, square, compliant box. The video is at https://www.youtube.com/watch?v=ce36SckrAHc

While there, take a look at our other video offerings on the NFFS YouTube channel, https://www.youtube.com/c/NationalFreeFlightSociety. You will find play lists specifically addressing SO needs.

Coach Chuck

[bjt4888]

Did you go to your first event, and find that your box was oversized, or your plane did not fit fully into your box?

Fear not, you are not looking at a complete rebuild!

Coach Brian has put together a video on trimming a few (or more) mm from your wing span without destroying your plane. Also some tips on making a nice, square, compliant box. The video is at https://www.youtube.com/watch?v=ce36SckrAHc

While there, take a look at our other video offerings on the NFFS YouTube channel, https://www.youtube.com/c/NationalFreeFlightSociety. You will find play lists specifically addressing SO needs.

Coach Chuck

Chuck,

Thanks for posting. I'm also going to post this under its own heading.

Brian T

[sneepity]

Where in the room should you stand when releasing your flight?
I've been standing in weird locations and it's caused my flight to hit the walls D:
B)

If the model has a consistent left hand orbit, then assume your launch is at the outside point of a radius of a circle. You will launch such that the model will complete that circle and fly over you (if remained standing there). If the model flies an erratic flight pattern, those reasons need to be addressed first.

Other factors can play into where to launch. Observe other airplanes as they fly. Note if they seem to drift towards one end of the site. launch to maximize your flight without ending up drifting into a wall or other obstructions. Always consider "court sense" and do not launch it the expected orbit will collide with an obstruction.

Good Luck!

Thank you so much!!! I will keep that in mind :)

[randomdogonapc]

So, I’ve been digging for articles and posts on propeller design on the NFFS website, and I found two things that intrigued me. One was an article titled, “Prop design and carving”, which provided some useful insight on making propellers. Another, was many articles discussing the Larabee prop planform, along with an excel sheet. I was wondering whether anybody knows more about this “Larabee design”, and whether I should spend my time carving a prop. Thanks in advance.

EDIT: Also, a clarifying question on prop design. What would would recommend as a range of P/D ratios for SciOly? I’ve been seeing a lot of conflicting information from “The Best of INAV”, and as previously mentioned, the NFFS technical library.

[jander14indoor]

Did you go to your first event, and find that your box was oversized, or your plane did not fit fully into your box?<SNIP>

Coach Chuck

For those who HAVEN'T built your box or plane yet, or are considering making something larger. I'll offer a big caution!

Be VERY careful of pushing the the rule limits. NEVER make it hard for the ES to decide if your device in ANY SO event meets the rules. ALWAYS consider the benefit of an extra couple of mm or even a cm of wing span to your flight time vs being tiered.

For example, reducing the wing span of a typical SO Div B plane 1 cm is about a 2-4 second penalty (or increasing it 1 cm is a 2-4 second gain!). This is NOT going to move you more than one place up or down in a tournament, if that!

So, make sure you build your box at least 0.5 cm to 1.0 cm under the rules and avoid the whole risk of tiering!! How close is based on your comfort building a box vs your confidence in your ES ability to measure accurately.

Oh, and the more accurate you build your box to keep it close to the rules, the more time you spend on that instead of FLYING!! Example, I've been building some boxes VERY carefully to just 3 mm under the rules. I have a lot of experience in building such things (after all, I have to build the gage to MEASURE your boxes!) and its taking me a week for one box. I'd never recommend such close tolerances for anything less than a VERY experienced builder.

Jeff Anderson
Livonia, MI

[coachchuckaahs]

double post, oops

[coachchuckaahs]

So, I’ve been digging for articles and posts on propeller design on the NFFS website, and I found two things that intrigued me. One was an article titled, “Prop design and carving”, which provided some useful insight on making propellers. Another, was many articles discussing the Larabee prop planform, along with an excel sheet. I was wondering whether anybody knows more about this “Larabee design”, and whether I should spend my time carving a prop. Thanks in advance.

EDIT: Also, a clarifying question on prop design. What would would recommend as a range of P/D ratios for SciOly? I’ve been seeing a lot of conflicting information from “The Best of INAV”, and as previously mentioned, the NFFS technical library.

Carved props are used in some outdoor classes and indoor in scale events. Generally pure duration events are going to use thinner sheet props or even built up props for ultra light classes. Look on hip pocket aeronautics forums for examples of prep builds for limited penny planes, which are similar to what is appropriate here. Also on nffs YouTube channel you will find a video I did on pro building. While the demo was for a smaller "Scraps" plane, the techniques are similar. https://youtu.be/HOCCgSHq8W8

Generally we have found p/d of 1.5 to 2 appropriate for SO. However, some are finding slightly lower P/D works better this year. The plane, especially C div, seems to need significant horsepower during letdown.

Coach Chuck

[randomdogonapc]

Thanks, I’ll definitely check out the video you made.

[Nonie]

Thank you to all the coaches for the wonderful information in this forum. It's very helpful(albeit a little overwhelming).

My story - I built a FF plane which worked really well in the beginning, did ~1 minute 30 seconds after 2 sessions and looked satisfactory. However, it crashed into the ceiling badly in the next practice and had to be mostly rebuilt. Then, I built 2 more from the kit.

Status of my planes:
- Plane 1 is rebuilt, but is behaving very erratically, not very balanced at all. I am not sure what I did wrong, maybe something is tilted or misaligned. The wing mount assembly had broken and both front and back mount sticks were cracked, the wing had come off. The mylar was torn in several places and patched up.
- Plane 2 is new. However, I glued the kevlar and truss to the MS before putting the rubberbands in, so I have to stick it with masking tape. It's not convenient to reposition the wing assembly.
- Plane 3 is the best plane yet. It gives me ~1 minute on good days and is a little erratic but better than the other two.

My main issue is that Plane 3 doesn't turn predictably. At the end of the flight the turn suddenly completely stops and the plane goes almost completely straight and into the wall or door.
What could cause the plane to change course like this?

Thank you!

[Astronomyguy]

Hey Nonie,

The coaches here can give you more detailed advice, but this is what I have to say:

1. Flight Log and information about your plane. Many people come in here and ask questions without providing any data or images from the plane, which makes it hard for us to help you. If you could take pictures of each of your planes we could better diagnose any potential irregularities. Also, provide a Flight Log (and make one if you haven't already). There are a lot of parameters that you should record, so here is mine if you want to copy it: https://docs.google.com/spreadsheets/d/ ... sp=sharing

Also, provide videos of your flights. If you don't want everyone to see them, you can PM them to the coaches and they can tell you what to change.

I'm missing a couple of things myself:

Torque before/after launch, because my partner is the one with the torque meter and he has not gotten it to work yet. This is one of the most important things to keep track of, going hand in hand with the number of winds per flight. In short, torque determines how high your plane will go and how many winds your rubber bands can take.

Reliable CG placement: Record your center of gravity (with the unwound rubber band on the plane) before each flight. You can use a pencil to measure it: just slide it under the wing and move the plane back and forth until it balances. You can use other objects too, including your finger, the tip of a knife, etc. I don't like using my finger because the margin of error is a bit too much - the wider/narrower the object is, the more/less accurate your measurement will be. I also recommend marking cm increments on the top of your wing post (the piece of balsa you rest on the pencil) so that it is easier to record your CG. It is measured in cm from the trailing edge (TE) or the wing. I'm not a very good follower of these rules because I test before school starts and find the CG without markings is a painstaking process that I do not have the time for between flights, but I will once I make my own markings.

Include these in your log, as well as everything I have in mine.

2.
Plane #1: Should be fixable once you record everything
Plane #2: Remove the kevlar and truss to put on the rubber bands (and the propeller, if you have to). I like to use an x-acto knife to cut the glue joints. Anything similar, like a pocketknife, could work too. You can also use acetone to soften them up. It's worth the hassle to have an easily adjustable wing mount.
Plane #3: Again, can be improved once you record everything.

3. Concerning erratic flights:

This may be due to external factors acting upon the plane. Are there any air currents from open doors, an HVAC system, or people moving near the plane? All of these could cause the plane to wobble a bit. After launching my plane, I don't move until the plane is well above my head and on the other side of the gym. Does the issue occur in a certain location in the venue? If not, then it's probably a trim issue. Your plane going straight sounds like you have little to no stab (horizontal stabilizer) tilt. It's the main trim factor affecting turns in the cruise/descent stage of your flight. Record stab tilt in your log (It's labeled HS tilt in Plane Information for mine). Increasing it will result in tighter turns during the cruise/descent stage.

Hopefully this helps, the coaches and more experienced flyers will be able to confirm/deny my suggestions and provide more information.

Edit: All the parameters you need can be found in the flights at the bottom of the log (you need to scroll down). My earlier iterations of the flight log are on the same spreadsheet and do not contain the accuracy, technique, or parameters that I have in my later flights.