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Pumpkin drop event

FT Flyer weight/cg issues

#1
Hello all,

I recently completed my first FT Flyer, maidened it, and have already gone through 8 props and many many crashes. I apparently built her ok because she's still alright aside from some scuffed corners. I simply have not been able to get this plane to fly correctly. I am a first time flyer; however, I've been practicing in the simulator for weeks while I waited for parts to come in, and I can take off and land with ease now in the simulator. My FT flyer, without landing gear or battery (<50g 3s 500mah), weighs 333g. The cg in this configuration is underneath the servos (servos placed according to flite test plans). The battery brings the cg forward only slightly, not even an inch. To get my cg roughly an inch behind the cg indicators on the plans I had to attach 110g to the front of the plane (total weight of plane w/battery and landing gear: 491g), but now I can't get it to take off (from the ground). I haven't tried hand launching it with the gear, as that's how I broke 7 props yesterday. I had not built my landing gear at that time since I had watched many videos of the plane flying without it. It was fairly windy, but where I live there is rarely a calm day so I'll just have to learn to fly in wind I guess. Anyway, I was wondering if my flyer is underpowered/overweight and where a flyable cg is. Internet research has told me a general rule for cg is 20-30 percent from the front of the wing, but I would have to add quite a bit of weight to get it there. Would anybody be able to provide some of their own weight/cg statistics? I've heard so many great things about this plane and would love to get into the hobby, but so far it has been a very frustrating experience. I'm running a Turnigy 1300kv motor with a 9x4.7 SF prop. I've been looking around the forum for some answers on this topic, and you all seem like really nice people. I look forward to whatever advice might come from this, even if it means I need to start over on this plane. Thanks guys, and happy flying!
 
#3
Try removing the front weight and then hand launch it. Nevermind the CG. I have never really looked at the cg in my flyer and it flies fine. I always use handlaunches though.
 
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#4
I have to tell you that I just came in from a successful sunrise flight and I have had many such flights this week.I had a big smile on my face. Over a year ago however I was squarely in your shoes. Build and crash...build and crash...buy props....buy more stuff....build and crash.

The challenge is great to learn to build and to fly at the same time especially without direct help. The usual answer to find a club is often bypassed. It is helpful however. You would get a little piece of knowledge here and a little piece there.One very helpful thing for me was an experienced RC pilot talking me through a flight while I was doing it. This helped my avoid that turn,roll,dive,crash syndrome.That really taught me to keep the plane level and start to correct ASAP.

I like the FT Flyer. It was one of my early successes. Not at first though. I rebuilt it several times, learning a little piece each time.
The wind is tough one though.I would still try to fly at the least windy times. In fact I still do this. Some lights on my Bloody Baron really help me to see it at dusk. I can see the plane without them but not well enough for orientation.I also used lights on my FT Flyer after I learned to fly it.

Broken props are so frustrating. I have found that APC SF props are very durable and often survive crashes. I use them whenever I can. They are about $3 US apiece and very worth it. Oh... a determined pilot like you or I can break them but we have special skills. HSVL (High Speed Vertical Landing).

Just keep trying and learning a little at a time. Flying will be all the sweeter for the effort.
Good Luck,
LooseBruce
 
#5
Welcome to the forums Jerronimo3000! I know it can be frustrating when things don't work out right. I had a similar start. A few things you might try until you can rebuild with DTFB. 1. Remove some paper from the foamboard on the tail. Just don't pick the hinge side of control surfaces. This will help with c.g. and lighten the plane. 2. Use a prop saver instead of the regular collet prop adapter. This will save you money and time in the long run. 3. Make sure the landing gear and battery are a far forward as possible (without hitting the prop).

With an aft cg it is not going to handle well. With it being heavy, you have to fly faster to maintain flight. This makes for a bad combination. Lightening the tail and it will help with cg and weight. It might not be enough. You could try removing some paper from the back half of the wing. Underside would be prettier but both sides if it still doesn't balance out.

My heavy trainer FT Flyer weighs 360g with landing gear and 3s 1000mah battery (& lots of tape and glue). My newer ones weigh closer to 260g with a 2s 800 and fly great (and slow)!
 

TexasTeacher

Ready to Crash
#6
The Eflite Prop Saver is great. I got it at my LHS for about 3 bucks, got a package of 10 #17 o-rings at Lowe's.

First day i took my FT Flyer out to fly i broke 3 props over about a 25 minute flight.

With the prop saver i have not broken a prop yet,even though i was dumb and trying to fly it on a fairly windy day, was fin into the wind, was beast at any other orientation to the wind. I did find out it can fl inverted for a short time :)
 
#7
Also, check the recommended prop for the 1300kv motor. A 9x4.7 prop might be too big for a 1300kv on 3s but that really depends on the size of the motor. If it is small blue wonder motor, a 8x4.7 or 7x4.5 might put out more thrust.
 

razor02097

Rogue Drone Pilot
#8
When I built my FT flyer I went by the CG marks on the plans. http://assets.flitetest.com/article_files/FT-Flyer-Swappable-FULL-SIZE-PLANS_1360987085.pdf

I fly a park 300 1000kv motor with an 8X43 prop on a 3S 900mAh battery. That is a pretty heavy setup like PhenomPilot said it likes more speed to stay airborne.

I would definitely say the weight probably caused the poor performance. If you build a new one I hope it will fly better! The FT flyer is a blast!
 
#9
Hi guys! Thank you all so much for your responses. I am definitely encouraged knowing that I'm not the first one to fail at building this thing. I ended up deciding to simply rebuild it with Adams board, and the early weigh ins forecast that she'll be about 300g, with modified custom landing gear. Today is one of the calmer days (5-10mph winds) so hopefully I'll be able to get out and maiden my slimmer FT Flyer :)
 
#10
Oh, I forgot to mention that I do have a prop saver, but it seems to be my landing gear that saves my props! It takes the bulk of the impact, leaving my prop a little roughed up but without any bends or stress marks.
 

razor02097

Rogue Drone Pilot
#11
Let us know how it goes!


Does your landing gear contact the prop during the landing? I am using some wire gear bent the same way as FT videos. I've never had the prop break because of the landing gear. Both landings did a nose over but it was because of the tall grass and the small wheels.
 
#12
Oh, I forgot to mention that I do have a prop saver, but it seems to be my landing gear that saves my props! It takes the bulk of the impact, leaving my prop a little roughed up but without any bends or stress marks.
BTW, the post about removing the paper from one side at least of the elevator, stabilizer and rudder is very good. You can replace it with clear packing tape and save weight in the tail. It may not seem like much weight but because it is so far back from the COG it is tremendous (like a fulcrum). I do it on most of my planes.
LooseBruce

PS on the FT Flyer it is also easy to remove paper on the inside of the extended fuselage.
After you remove so much tail weight you may be able to use a smaller battery up front and still balance. Total lower weight will make you slower.
 
#13
She flies!! My new one out of Adams board weighs in at 370g, heavier than I expected for sure. Really, I'm just extatic that I made it into the air and back down several times before I got adventurous and crashed landed from 25 feet up after too hard of a bank. (is that what a turn with the rudder is called? A bank?) I broke my last 8x4.3 prop, but I still have a couple of those 9x4.7s. I used one earlier, but I noticed my motor got uncomfortably hot to the touch after only a couple of quick launch and lands. I know nothing about props and motors, just purchased the recommended stuff and then a slightly larger propeller pack because I has already bought and broke all of the 8x4.3s at my LHS. Is it normal for a motor to get that warm, or is the propeller too much for it? Could I use something other than a 8x4.3? (turnigy 24g 1300kv motor from the recommended electronics)
 
#14
The propeller is too much for it on 3s. You could try to cut the 9x4.7 props down a little but it is suggested to balance them. If the hobby shop has smaller props like a 7x5 or 7x4, they should work. You might not get quite as much thrust but you should get longer run times.