Archive for April, 2009
Low Cost Radar Gun,Originally only $69.99, Now most sites are selling it for about $79.99
Tracked Medium Sized Planes up to about 200 to 250 feet away.
Speed Readings Appeared to be Fairly Consistant on multiple passes.
Very Easy to use (One Button on the back and one trigger button)
Large easy to read LCD Display, Can be set up to display MPH or KPH
Felt pretty durable considering cost, ruberized coating with good finish.
High Fun Factor, Great to find out exactly how fast you are flying.
Overall 5-Star rating for Fit, Finish, Ease of Use and High Fun Factor.
We wanted to Provide a link to Amazon for those who can not find the below products locally. We do suggest you check your local stores first so you do not have any extra costs as would be related to shipping and handling.
Weller TB100PK 30Watt Hot Knife Type Tool
This tool is espcially great for carving and creating pockets in Foam.
Also great for creating small channels to run servo and other wires.
Great to use on EPP, Blue Core, White Insuallation Foam and others.
Perfect temperture, not too hot, makes it easy to acurately control.
We Bought our tool at Lowes Hardware Store. Sure other hardware stores have it too.
Logan 1500 Foamboard Cutter
- This tool is especially good at cutting 45 degree bevel cuts.
- Flip blade and tool over and can be used to cut straight 90 degree cuts.
- Very durable build and easier to hold than a Xacto knive or Box cutter.
- Works great on Foamboard, Depron and thin cuts of EPP
If you already have a Twitter account you can find us at the following link:
After you go to the link and are logged in just click on “Follow” and you will be added to the rcFoamFighters Follow list.
Haven’t heard of Twitter?
For those of you who may not be familiar with Twitter, its a FREE service that many people are using to keep in touch and up to date with Friends, Family, Company’s or other. It is quickly being recognized as a vital part of the Social Media World.
Twitter is used much like text messages are used on your cell phone. With twitter you can send little brief messages to people who are in your Twitter Follow Group. You can even upload or download Twitter messages right on your phone. This way people can almost instantly know what your up to, or be informed of news, your thoughts at that moment or anything you want to communicate.
How will rcFoamFighters be using Twitter?
rcFoamfighters will begin to announce all our new video uploads with Twitter. We will also announce new Blog Entries, General News and or anything we feel would be good for our friends and viewers to know. So with this service you can be kept in the loop and know what rcFoamFighters is currently up too.
How Do I start a Twitter Account if i don’t have one?
If you do not already have a Twitter account and want one, it is very easy to set up. All you need is your own email address. Then Click on the “Get Started-Join” button and follow the prompts.
Link to Twitter: http://twitter.com/
So now it’s time to start Phase 1 of the Bulletproof Plane Build Along. In the below videos we start with going over the tools needed and then move on to drawing the wing layout on the EPP foam.
Link to Wing Drawing Dimensions (This is not a template):
Stay tuned, this build will feature more videos soon.
Big News! Dick Kline Inventor of the KF AirFoil Contacts rcFoamFighters.
The following posts are excerpts from e-mails sent to us from Dick Kline along with information provided by him on the various types of KF Airfoils. If you are thinking about experimenting with any of these airfoils or just want to know more about them this information should be very helpful.
(Copy of Email from Dick Kline to rcFoamFighters on 3/28/09)
Hi Frank and Paul…
You both are more than welcome to do a video of the KF airfoil.
I’m delighted that you are interested in this concept that has been trashed by the experts for over forty years. They claim that it is too high in drag. However, when the step is applied to a flat plate it appears to go faster. The KFm4 goes even faster than the other KFm variations.
When a KF step was applied to the end of a prop it increased the thrust by almost 9%. If the step produces too much drag, how can it become more efficient.
Personally, and I’m no expert, but I believe that 50% of the KFm4 produces no direct friction or drag because it is air against air. That’s kind of mind-blowing to think that half of the airfoil doesn’t come in direct contact with the air around it.
Have you guys ever heard of the Kamm effect? In the 1930s, Wunibald Kamm who was a German aerodynamicist, chopped off the rear end of his racing car. At that time it was thought that the tear-drop shape was the most aerodynamic. The blunted rear end proved to be more aerodynamically efficient, which is why most cars today come with blunted rear ends. That includes the hybrids, which are looking for fuel economy.
In fact, the Boxfish has inspired blunted rear end designs.
Here is one study done in 1998 that shows some positive characteristics of the step concept.
Finally… Here is a list of the positive characteristics that the KF airfoil has shown to date:
1. The KF airfoil handles a wide range of speed from very slow to very fast.
2. Normal airfoils are designed to either generate a lot of lift in order to carry more weight, which means they must be thicker to produce more lift, or they need to be thinner in order to fly faster thus sacrificing lifting heavier loads. The KF airfoil can do both of these jobs extremely well.
3. The KF airfoil has a much greater range for its center of gravity (CG). A conventional airfoil would normally have a CG about 33% back. The KF airfoil can be moved back as much as 40%, thus allowing it to carry a heavier load. The further back the center of gravity is the more desirable it is because of the center of balance. And, it can also handle a shifting CG and still give you control authority.
4. The KF airfoil has great control authority. It’s control surfaces remain effective through a large range of angle of attack (AOA). Even beyond a 60º AOA. This is also evident by its ability to have a very fast roll rate with full aileron and rudder control at very high angles of attack.
5. Normally, all flying wings require some reflex in flight. Reflex, which will produce some drag, means that the ailerons are angled upwards slightly in order to keep the nose of the aircraft pointed up. It is also well known that flying wings are extremely unstable and stall easily in flight. The KF airfoil requires zero degrees reflex on a flying wing which means no drag from the reflex action. It is a very stable platform. It is capable of flying without stabilizers or rudder, which means that two components which cause drag are eliminated.
6. The KF airfoil appears to have better air penetration. High winds seem to have little effect on how it performs. People have reported not being able to fly their aircraft during strong wind periods while the KF airfoil continues to fly smoothly. It appears as if it rides on rails.
7. In addition, the KF airfoil doesn’t appear to be affected by weight increases. It has been reported that the handling of the aircraft doesn’t seem to be affected by adding additional weight. In one case, 4.5 oz. of lead was added and it was able to handle the added weight with ease. In another case, a KF glider which was facing 22 mph wind, flew very well when nearly 100% lead weight was added to it.
8. At high angles of attack, the KF airfoil remains unstallable. The center of gravity and center of pressure appear to move backward thus preventing a loss of lift.
9. The possibility exists that the KF airfoil may be more fuel efficient because one quarter of the airfoil produces little friction due to the trapped vortex pitting air against air. A normal airfoil produces friction over the entire surface.
10.Unmanned aerial vehicles are extremely expensive aircraft. The loss rate in the military is rather high – over 20%. The KF airfoil is a minimal structure which is very strong and simple to build. It would greatly improve on the survivability of these planes because of all the reasons outlined above. In addition, because it penetrates the air so well and is extremely stable, it will produce better photography. Because of a better center of gravity, it will be able to carry more weight, either extra cameras or extra batteries for longer flights. And, because of its ability to penetrate air better, it is not affected as much by higher wind gusts. It has been shown to fly in strong winds when all other RC aircraft were grounded.
And, now for the most amazing aspect of all… the KF airfoil has no apparent bad habits, vices or negatives that have shown up. All airfoils have their positives and their negatives, because each one is designed to do a specific job. Thus, a given airfoil can do certain things well, but do poorly in other areas. To date, nothing negative has appeared on the KF airfoil.
The concept behind the Kline-Fogleman airfoil may be hard to understand because it is so different from present aerodynamics. The KF concept uses a vortex, which attaches itself to the KF airfoil behind the step and becomes part of the airfoil. This means that one-quarter of the KF airfoil is air against air. This also means less friction and greater efficiency penetrating the air. It is important that the step be between 7% and 9% at 50% of the chord on top. When the step is on the bottom, the step should be at 40% of the chord. When the step is on top, it will produce higher lift than on the bottom, but the airfoil works well right side up or upside down. With the KFm4 airfoil, which has the step on the top and bottom, 50% of this airfoil is air against air, which means no direct friction or drag.
– Dick Kline
P.S. I’d be very interested in your own personal experiences with the KF airfoil concept. I think that there may be a difference between what is seen or studied in lab conditions is not the same as what happens in the real world. So many people who first see the KF airfoil react to it by saying, “That thing can’t fly.” Somehow it does inspite of everything that we have learned about the way a wing is supposed to generate lift.
Thanks again, guys, for your interest.
Pictures of KFm Airfoil Variations:
Pictures of Kline-Fogleman Effect:
rcFoamFighters would like to thank Dick Kline for
sharing his thoughts, words, time and the above documents
We will soon be using KFm Airfoils on up
coming projects and seeing how they perform.
Please click on the below link for more in depth information
on the performance of the KF airfoil provided to us from Dick Kline along with the information in this post.
List of parts for Bullet Proof Plane build along #1
Delta Flying Wing design with KFm4 airfoil
EPP Foam from (rcskyflyer.com or rcfoam.com)
(1) 15mm EPP Foam Sheet 36″ x 24″
(2) 8mm EPP Foam Sheets 36″x 12″
From local hobby shop or craft store
(1) 3/32″x 3″x 24″ Basswood Sheet
(1) 3/8″x 3/8″x 24″ Basswood Strip
From HomeDepot, Lowes, or hardware store
(1) Roll of Henry’s 183 6″x 25′ Fiberglass Weave
(1) Can 3M 90 High Strength spray adhesive or equivalent
(1) Roll 3m Scotch cross weave strapping tape
– strait edge ruler 36″
– 90 degree square ruler
– box cutter and spare blades
– wood rasp
– handheld hotwire cutter (Styro Cutter)
– sanding block (course grit)
– fine tip marker
List will be updated for Phase 2
Step 1: Selecting the Motor
First you need to know the estimated overall flying weight of the plane you are planning to build. If you are building from already made plans they will usually list the estimated All Up Weight or AUW. If you are building totally from scratch, try and find an already made plan to a plane that is fairly similar in shape, size, wingspan and building material to the one you want to build. You can use the weight of the similar plane to get a real rough estimate to start with. After you have built a few planes you pretty much develop a good sense of weight dynamics and will be able to estimate right out of your head.
So now you have your estimated weight of the plane. For this exercise lets say the estimated plane weight will be about 18 to 20 ounces. We usually like to make fairly high performance planes, so we always choose motors that are overrated for the target weight of the plane we are going to build. We usually look for a motor that will put out a thrust level of around 1 to 1.5 times the All Up Weight of the plane. For unlimited vertical flight we prefer it to be 1.5 or better. So in this instance we would need to pick a motor with about 20 to 30 ounces of thrust to get to that 1 to 1.5 power to weight ratio we mentioned above. For this example we will choose the Suppo BL-2212/6 2200kv Brushless Motor Rated at about 27 ounces of thrust with a 6×4 prop and 3S Lipo.
Now that you have selected the proper motor for the particular project, it is important to know the Max Amp Draw the motor will demand. You can usually find this information on the manufacturer’s web site or the site you got the motor from.
Suppo BL-2212/6 2200kv Brushless Motor Rated at:
Max Efficiency @ 22amps
Max Amp Draw (28amps) for 60sec
Step 2: Selecting the ESC
Now that you know what amount of Amp Draw your motor will demand, you need to choose a properly sized ESC. You will need to select a Brushless ESC that has a slightly higher constant max amp draw rating than the motor’s max amp draw. Most ESCs have an over amp shut down built into them to protect the ESC and motor from drawing to many amps. It is very important NOT to choose an ESC with too high an amp rating. An oversized ESC can allow too many amps to get through and as a result you could burn up your motor. (Unfortunately we learned this lesson the old fashion way, as I’m sure some of you have….LOL)
So for this example we would choose the following ESC to match the motor:
Suppo SP-30A ESC Rated at:
Max constant Amp draw (30amps)
(Now that you have the Motor and ESC selected Go to the post “How to Find Your Lipo-Battery’s Maximum Constant Amp Draw” for help on picking the proper Lipo-Battery to power this system)Link to a PDF copy of this Document: http://rcfoamfighters.com/FileDownloads/How_To_Select_Brushless_Power_System.pdf