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Flying Probs with the Firebird Freedom

Old 11-02-2006, 05:54 AM
  #151  
Sovereign
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AEAJR, ejet42, and flyingbear, thank you very much for your feedback. AEAJR, I too have recently checked out both the Aerobird Challenger and HZ Super Cub. Both have recieved good reviews on this and other sites. My concern with the Aerobird is its Zone 2 classificiation, whereas with the Super Cub, I fear totaling the propeller and motor in case of a nose dive, being as how it is located on the nose rather than back of the fuselage. Then again, crashes are a part of this hobby and that really shouldn't keep me form an otherwise great plane.
Ejet42, thanks for the great info on the Commander 2. I only hope my LHS carries it, being as how I'd rather support the one LHS in my entire area than rely solely on internet purchases. I've seen videos of this model in flight and read a few reviews, all of which now have me considering a top level wing model over a mid-level wing like the Freedom. That final note on the wind around these parts and the best time to fly is something else I'm glad you touched on. I'll definately keep that in mind. Again, thank you all for your help. I'll keep you posted on my final decision and look forward to leaving feedback on my early piloting experience. Happy flying.
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Old 11-02-2006, 06:33 PM
  #152  
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I think you will be happy with the Commander II as a good first plane. Challenger would also be a good first place if you stay away from using the pitch control for the first 5-6 flights and fly it at ~50% throttle.

One of the most common reasons for crashing is stalling due to excessive up elevator control input. Commander II solves this problem by eliminating pitch control.

Good review / video.

http://www.rcgroups.com/forums/showthread.php?t=452851

Commander II wing appears to generate more lift so it flies slower than the Challenger and turns are flatter - less likely to drop a wing and spiral into the ground.

One tip: Adjust the throttle down to 50-75% soon after launch for a smooth climb instead of allowing the plane to nose up / stall / recover. You can also adjust the tail screws for the right balance between best gliding and motoring flight.

I haven't tried flying the Challenger with the Commander wing yet. My guess is that it will fly just like the Challenger (assuming I don't use the pitch control stick) but allow easier adjustment of the elevator trim.


Clint
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Old 11-02-2006, 07:07 PM
  #153  
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Cbatters, thanks for the feedback. I'll visit my LHS tomorrow and varify which of these two models they carry, if any, or both. Of all the replies I have recieved since I first posted, the Challenger has popped up the most and with, perhaps, the best feedback. I agree the addition of a 3rd channel (pitch) is probably the number one cause of the up/stall syndrome in 3 channel models (for beginners, such as myself, at least) so perhaps a 2 channel is the way to go for now, although, if you think it wise, I'd like to go with a 3 channel like the Challenger and refrain from using any elevator at first, only so I may transition into 3 channel flying without having to purchase a new plane. One other thing, when you refer to the Commander, do you mean the Commander 2 or is it an earlier version of the Commander you recommend? The only one I've come across is the Commander 2, also a 2 channel and also top-wing design. Thanks for your help.

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Old 11-02-2006, 07:21 PM
  #154  
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Originally Posted by Sovereign View Post
Cbatters, thanks for the feedback. I'll visit my LHS tomorrow and varify which of these two models they carry, if any, or both. Of all the replies I have recieved since I first posted, the Challenger has popped up the most and with, perhaps, the best feedback. I agree the addition of a 3rd channel (pitch) is probably the number one cause of the up/stall syndrome in 3 channel models (for beginners, such as myself, at least) so perhaps a 2 channel is the way to go for now, although, if you think it wise, I'd like to go with a 3 channel like the Challenger and refrain from using any elevator at first, only so I may transition into 3 channel flying without having to purchase a new plane. One other thing, when you refer to the Commander, do you mean the Commander 2 or is it an earlier version of the Commander you recommend? The only one I've come across is the Commander 2, also a 2 channel and also top-wing design. Thanks for your help.

Sovereign
Was referring to Commander II - have never flown the original Commander.

The Commander II turns much flatter than the Challenger due to the differences in the wings. (If you turn too sharply with the Challenger you can easily drop a wing and get into a downward spiral which is probably why they rate it Zone II.)

If you have never flown before, I think you will crash less and have more fun with the Commander II. (And you can move up to a 3 channel after you have mastered 2 channel instead of crashing/repairing a 3 channel.)


Clint

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Old 11-02-2006, 07:37 PM
  #155  
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Just read the review of the Commander 2 and saw its flight video. Very impressive and definately looked like an enjoyable experience (wouldn't want to be discouraged from the hobby by my first plane...or ever) This is just what I'm looking for and would undoubtedly provide a better intro to rc flying than the Firebird Freedom (which sould have been designated a Zone 2 plane like the Challenger even if it doesn't boast the same speed capability). I'll give my LHS a call and varify if they carry the Commander. On my first visit, they highly recommended the Firebird Freedom. I have, since, directed their attention to this thread. With so many aspiring RC flyers in my area just now entering the hobby, I'd hate to see any of them turmed away by an inappropriate beginner level plane. Again, thanks for all your help.

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Old 11-28-2006, 05:06 AM
  #156  
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I picked up a used Freedom as a possible "next plane" for my son and had a very positive experience flying it this morning before work. Very smooth flier and surprisingly good glide.

Three differences from my first attempt at flying the Freedom which was very, very negative:

1. Act OFF

2. More flight / launching experience

3. 50% throttle and a firm level toss and it climbs right out without any hint of stalling/rolling.

In my earlier attempt, I used full throttle to hand launch and it rolled left and crashed into the ground twice (at which point I stopped before I damaged the airplane.) This time I used 50% throttle and there was no hint of rolling / stalling and it climbed steadily. Turns were surprisingly flat/controlled compared to the Challenger.

Wing generates a lot of lift and flies slower than the Challenger. Flies like a Commander with pitch control which is what I was looking for my son.

THROTTLE
Manual recommends hand launch and full throttle. In my experience 100% throttle caused the plane to nose up, roll left and crash X2. (With a very firm toss, I am now confident you could launch successfully at 100% but 50% throttle is more than enough power to get it airborne and a gentle climb out without any hints of torque roll / stalling. MUCH better for a first flight / new flier.)

FLYING SPEED
I was fully expecting it to fly fast based on the heavier weight (23 oz versus 17) and reports about tip stalling. Flies more like a Commander than a Challenger in terms of stability (probably due to high lift wing / upturned wing tips.)

First impression is that it is as easy or easier to fly than the Challenger in Beginner Mode (where only one ruddervator moves up when turning.) MUCH easier to fly than the Challenger in Expert mode which is very responsive to the stick and requires up elevator to maintain altitude when turning.

Was pleasantly surprised how well it flew and it may be a good "next plane" for my son. (Acid test will be ROG performance because my 7 Y.O. son always launches from the ground.)

I'll post again after I have had a chance to fly them back to back in the same conditions.




Clint
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Old 11-28-2006, 05:27 PM
  #157  
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Hi Clint,

Glad you are having good experiences with the Freedom. We are still operating 3, and have positive experiences except for the occasional tip stall or control confusion on landings (right-left) . We no longer do hand launches, but take off (paved road, 5 lanes wide). As long as the glide speed is maintained, you can accomplish the most beautiful landings with a "flare" right at the end.

Two of the Freedoms are stock, while mine is the hybrid with the steerable tail wheel. I really enjoy that! I am running a 3S 2000mAh LiPo, but am paying the price with 480 motor wear. Now, I can only run about 125 Watts at WOT. I'm certain the higher voltage and current have burned the commutator/brushes. It ran better when I first started than now, but it still has more power (grunt;grunt - Tim (the Tool-Man) Taylor syndrome) than the stock set up. I will install a brushless something (haven't decided on inrunner or outrunner), but will tell you that 150 to 200 watts make this plane a really impressive flyer. Consecutive loops, etc. from level flight! I plan to check out the "Swift" wing and possibly add aileron control if it will fit reasonably well. I'll deal with the yellow wings later.

By the way, I absolutely recommend a What-meter (brand name) or similar device so that you can know exactly what your equipment is doing (if you don't already have one). It is one of the best $50-$60 an electric flier can invest in the hobby! This device will show instantaneous and totalized current in and out of the battery as well as battery voltage (helpful to determine if the ESC is cutting off where it is supposed to (or where you think it is supposed to)), and actual instantaneous wattage (voltage x current) to help you "prop" the plane most efficiently without overstressing components.

That's my soap box for today. It's great that your son is enjoying this great hobby. I tried to get my grandsons interested, but there was too much competition from other activities - but I am still hopeful.

Henry
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Old 11-28-2006, 06:24 PM
  #158  
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I have always liked the looks of the Freedom but had a terrible first experience trying to get it airborn. (Unfortunately the manual discourages ROG and instructs full throttle hand launch which will result in a crash unless you give it a very strong toss.)

Still probably not a greeat first plane without an instructor but might be a good second plane after a Commander II to get some basic flying skills.




Clint
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Old 12-04-2006, 02:57 AM
  #159  
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Flew the Freedom for a total of 15 minutes and 5 takeoff/landings.

Absolutely no problems until I began the last downwind leg before turning upwind to land - it stalled violently and fell out of the sky.

Wind was a little gusty - probably 5 MPH with gusts to 10 MPH. My guess is that I got tagged by a little gust while flying slowly downwind causing the plane to stall. Worst stall I have ever experienced. The plane did not even begin to recover in 40' before crunching into the ground.

Broke the boom right where it enters the tail mount. Pretty much the worst possible location for a break. I am going to try a repair with epoxy but I will probably have to cut off a section of the boom and either drill out the tail mount or get section of boom with the tail mount intact.

HobbyZone does not sell tail booms but Hobbico sells tail booms that I may be able to get to work.


Clint
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Old 12-04-2006, 03:56 AM
  #160  
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Hi again, Clint,

Sorry about your experiences with the Freedom. This is the "tip stall" that has been discussed and that the Freedom is famous for. I think you can get a body / boom (no electronics) for around $20 from your LHS if you want to go in that direction. The boom from Hobbico probably doesn't have the correct platform for the tail feathers.

We are flying 3 Freedoms at this time, and to be honest, we are not having problems BECAUSE we are keeping them flying fast. Our minimum "drive it around the sky" are about 5/8 throttle with enough down trim to provide level flight. This keeps the speed up. Every Freedom has the control surfaces set slightly down.

Also, every very time we have hand launched a Freedom, it has been at full throttle, but the initial control input is to push forward on the stick immediately to keep the plane from climbing and stalling! I don't think we ever launched at less than WOT.

The worst flying conditions are when definitely when gusts are present - These conditions are much more prone to produce an instanteous low air flow condition over one wing (and not the other) and the ensuing tip stall (to one side). And you are absolutely correct about the (lack of) recovery. Unless you are absolutely waiting for the stall with opposite rudder and up on the immediate "ready", a 30-50ft drop is inevitable. Fast (1/4-1/3 throttle) long, low and fast approaches in these conditions are the only safe way to get it down, with throttle off at 5ft and flare (up elevator) immediately before touchdown. Even knowing this, I have experienced tip stalls at 3ft, but no damage (except pride) from this altitude.

Keep us posted on your repair experiences.

Henry
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Old 12-04-2006, 05:37 AM
  #161  
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Already fixed and it looks pretty strong.

Used epoxy to glue the boom back into the tail mount and then used small carbon rods under the V of the tail support that extended forward to the boom for reinforcement.

The break occurred in the boom right at the forwad screw. On any future Freedom I would reinforce the tail mount with a fillet of epoxy before flying to reduce the risk of the same failure.

If it doesn't hold, I will try the Hobbico boom and a hobbyzone repair sleeve.

FLYING
Prior to the stall there was not a hint of any flying problems. The plane flew very well at low and high speed. Moral to the story is that you need to keep the nose down and the speed up especially when running a down wind leg.

I would describe the stall characteristic as harsh, unexspected and unforgiving - not good for a beginner.


Clint

PS: If you tape over the lower sensor with electrical tape, the ACT on/off switch becomes a nice dual rate control without getting tripped up with ACT.

Last edited by cbatters; 12-07-2006 at 01:32 PM.
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Old 12-04-2006, 06:56 PM
  #162  
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BTW -

ejet42 - Just realized you were the one that started this thread....

I thoroughly enjoyed flying the Freedom - right up until the abrupt / harsh stall / crash.

My guess is that the complex contoured wing is extremely efficient above some minimum air speed but lift falls off abruptly below that speed resulting in violent stalls.

I had assumed that the violent tip stalls were happening while people were turning at low altitude / low speed getting ready to land. Mine was flying straight and level on a down wind leg with no control input when the stall knocked it out of the sky.

If you get a chance, please post a pic of the dihedral you added to the wing to reduce the tip stalls.

The other choice might be to try a Swift wing with more traditional geometry.



Clint
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Old 12-04-2006, 08:49 PM
  #163  
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Wondering outloud if part of the issue and the variations between planes is a sagging wing problem - reducing the dihedral that the designer intended for a stable / predictable flight.

(If you remember reading the review in one of the magaznes, the original plane flown by the reviewer had a bad case of drooping wing syndrome - surprised that the plane flew at all. Some Hobbyzone pics show the wings upswept where others are almost gull winged which has to affect the performance.)

MORE DIHEDRAL
I am going to try a simple mod, stringing a thin piece of monofilament line between the wing tips and over the fuse. (It only take a small amount of force on the line to add an extra inch of dihedral.)

Similar to the extra dihedral mod suggested earlier in the thread but easier to do and easily reversible.

MOVE CG FORWARD
Also wondering if anyone is flying the plane with an additonal .5 - 1.0 oz (2-4 quarters) in the nose to see if it improves the low speed / stall characteristics.

The larger 8 cell battery would also shift the CG forward. (About the same effect as adding 2 quarters / .5 oz to the nose.)

TAIL REPAIRS UPSET BALANCE
As little as 4 grams of glue or tape added to the tail would require nearly an ounce of weight in the nose to compensate.

(I see some scary test flights in my near future.)


Definition of lunacy - intentionally trying to stall a Freedom!



Clint

Last edited by cbatters; 12-04-2006 at 10:15 PM.
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Old 12-06-2006, 08:00 PM
  #164  
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STALL STRIPS FOR THE FREEDOM??
I just notices that the right wing has a mold protrusion on the leading edge near the wing tip that acts as a stall strip. This would cause the right wing to stall before the the left. I will try removing the protrusion.

Perhaps what this plane really needs are 1-3" stall strips installed near the wing root on both sides to produce a more controlled stall.

Stall strips
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A stall strip factory installed on an American Aviation AA-1 Yankee


A stall strip is a fixed aerodynamic device employed on fixed-wing aircraft to modify the airfoil used. They are usually factory-installed or, on rarer occasion, an after-market modification. Stall strips are almost always employed in pairs, symmetrically on both wings. In rare installations they are employed as a single stip on one wing to correct aberrant stall behaviour.
A stall strip alters the wing’s stall characteristics and ensures that the wing root stalls before the wing tips. This is usually as a result of initial aircraft flight testing which shows that the existing stall characteristics are unacceptable for certification.
In some cases, such as the American Aviation AA-1 Yankee, stall strips are planned to be used on the wing from the start. In the case of the AA-1 the left and right wings were identical, interchangeable and built on a single wing jig, thus the more traditional use of washout in the wing design was not possible.
Stall strips can be an alternative to washout in aircraft design or they can be used as well as washout to improve stall performance.
Stall strips typically consist of a small piece of material, usually aluminium, triangular in cross section and often 6-12 inches (15-30 cm) in length. It is riveted or bonded on the point of the wing’s leading edge, usually at the wing root. Here it acts to trip the boundary layer air flow at higher angles of attack, causing turbulent flow and air flow separation. This has the effect of causing the wing root to stall before the outer portions of the wing, ensuring a progressive outward stall and aileron control through the stall.
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Old 12-07-2006, 04:54 AM
  #165  
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Hi Clint,
I started this thread because I had the exact same experience that you did!! I contacted Horizon Hobby and have received the exact reply that many folks that have answered this thread did; that being, "We have never heard of that happening before" - which proves one thing without doubt - HORIZON HOBBY SERVICE DEPARTMENT WILL LIE WITHOUT HESITATION, EVEN THOUGH THEY KNOW THEIR PRODUCT HAS ABSOLUTELY PATHETIC PERFORMANCE FOR A "ZONE 1" (BEGINNER) AIRCRAFT!!! I can promise you that this is the reason for the quick (still late) entrance to the market for the Firebird Swift.

I think it is interesting to note that the Swift has essentially the same wing configuration toward the tip as the rest of the successful portion of the Firebird line of products.

Now about your tip stall from the "Queen of Tip Stalls" - I can all but guarantee that your airspeed got really low. Even in straight flight, one wing will stop flying (generating lift) before the other, and we all know what happens next. If the wind is gusting even a little, these stalls are more likely to occur.

I was duly impressed with your dissertation and quotes regarding the stall strips. I have indeed seen them on light general aviation aircraft, but never knew what these triangular shaped sections were - and never asked. I do suspect that installing something like that on the leading edge of the Freedom wing probably won't have the desired effect due to Reynolds Numbers. It did start me thinking, though - what if you took a piece of balsa about 12" x 1" x 1/8" and split it diagonally in half (leaving two long triangular pieces). Then, CA this to the leading edge of the wing, keeping the triangular piece "flat" with the bottom of the wing. This would make the wing wider at the root section (by 1") and would have little to no effect during level flight, but should make the air flow begin to detach from the top of the wing earlier at the root section, causing the nose to drop earlier and maybe avoid the tip stall.

"Whachatink bout dat"? (translation: Your thoughts would be greatly appreciated)

Henry
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Old 12-07-2006, 12:02 PM
  #166  
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Dear Queen of Tip Stalls,

Please explain what you meant by
I do suspect that installing something like that on the leading edge of the Freedom wing probably won't have the desired effect due to Reynolds Numbers.
Last evening I added 4" x 1/4" trianglar piece on the leading edge near the root with tape. I'll see how it flies this AM.

Instead of living with the harsh tip-stall I bet we can fix it. All planes stall but they don't have to roll and flip over.



Clint

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Old 12-07-2006, 01:25 PM
  #167  
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First flight with stall strips - I think it worked.

Tried flying with the modified wings this AM (although it was really too dark to fly) A bit windier than I would have liked for a test flight (7-10 MPH) but I figured I could handle it.

Launched fine, started climbing, realized that it was really too dark to be flying so I figured I would throttle back, fly it once around the field and then bring it down. (It was so dark that I really could not see the attitude of the plane)

While flying the plane towards me on the downwind leg, it stalled - but did not snap roll like it did the other day. I lost ~20 feet of altitude but was able to recover and bring it down.

Needs more testing (with the lights on!) but we may be on to something with the stall strips.



Clint

PS: I think my flying days before work are over until the days get longer.
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Old 12-07-2006, 01:48 PM
  #168  
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Hi Clint,

First, it is the Firebird Freedom that has earned the title "Queen of Tip Stalls".

I probably need an engineer to help with a dissertation of "Reynolds Numbers", but it has to do with the size of molecules (in this case air molecules) and their motion around and over the wing. Reynolds Numbers are the reason that you can't make a precisely scaled down plane with a 1" wingspan fly the same as one with a 3ft. span.

I think that the effect on air flow over the wing caused by the relatively small stall strip shown in the picture on the general aviation plane would be more difficult to duplicate on a scaled down model plane - but that is not to say that it cannot be done, nor that what you are trying will not work - I certainly hope it does.

I am with you - I bet we can come up with a way to "fix" this problem. My "washout" that I added on one set of wings helped, but did not totally eliminate the problem. That plane has since been lost (fly away - I wasn't present when Ferd (flying buddy) let it get too far out and too low. It disappeared into a subdivision and we never saw nor heard from it again - had name, address and phone number embossed thereon. I guess some kids got an early Thanksgiving present! That was the only wing that I modified. My modified Freedom is flown with a stock wing, but with more "power on" most of the time for loops, and other limited aerobatics.

I have tested the tip stall tendency by cutting back to the half throttle indent with sufficient altitude (somewhere in this thread this was labeled as a definition of insanity) and slowly feeding in up elevator until a wing violently drops.

I have some 1/8" foam core that I may use to try the long (flat) triangle stall strip (hypotenuse becomes the wing's leading edge with the short side of the triangle up against the body) ...... triangle stall strip CA'd to the leading edge with the wing held flat to the work surface after you let me know how your addition works. I am thinking that I may make it a little longer and wider than I originally stated.

It would be nice to present the world with an easy "save" for the "Queen". (I still love the way the Freedom looks coming in for a landing when it is about 3 ft. above the deck!)

Good luck on your testing today. We fly tomorrow, weather permitting.

H2
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Old 12-07-2006, 01:53 PM
  #169  
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Wow Clint,

You were flying while I was writing! It was dark here at 6:30 AM - I guess that proves that the earth is round and that the sun does rise in the East!

....... but ..... What!! No nav lights??? No landing lights for the Queen??? Just what kind of stripped down aircraft are you flying?

..... and remember, there's always the 9:30 AM break and Lunch ......

H2

Last edited by Ejet42; 12-07-2006 at 02:28 PM.
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Old 12-07-2006, 02:40 PM
  #170  
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Clint and all,

I have been feeling a little guilty about my Horizon Hobby bashing in an earlier reply:

I contacted Horizon Hobby and have received the exact reply that many folks that have answered this thread did; that being, "We have never heard of that happening before" - which proves one thing without doubt - HORIZON HOBBY SERVICE DEPARTMENT WILL LIE WITHOUT HESITATION, EVEN THOUGH THEY KNOW THEIR PRODUCT HAS ABSOLUTELY PATHETIC PERFORMANCE FOR A "ZONE 1" (BEGINNER) AIRCRAFT!!!
In all fairness, and even though the "company line" has been to categorically deny all problems with the Freedom, it has been my experience that they will replace your problematic Freedom with another (still problematic) new Freedom when you return yours. They are quality people, but someone near or at the top of the organization needs to instruct the HH Service Department to simply state that "we have had some problems with the Freedom and we'll be happy to replace yours". Then at least they have maintained their creditability with the customer.

I hope someone connected to Horizon Hobby reads this.

Henry Hopper
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Old 12-07-2006, 04:47 PM
  #171  
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Originally Posted by ejet42 View Post
Wow Clint,

You were flying while I was writing! It was dark here at 6:30 AM - I guess that proves that the earth is round and that the sun does rise in the East!

....... but ..... What!! No nav lights??? No landing lights for the Queen??? Just what kind of stripped down aircraft are you flying?

..... and remember, there's always the 9:30 AM break and Lunch ......

H2
It was also way too dark up here at 6:30 AM to fly - ergo my stall and rough landing which unfortunately broke the tail boom repair I did a few days ago. (Would not have damaged a new tail boom.)

The good news is that the stall was completely different from the snap-roll stall of a stock Freedom wing. Plane still fell off to one side (as opposed to straight ahead) but it was nose down, did not roll very far and recovered quickly.

After I fix the tail I am going to extend the stall strip another another 2" for a total of 6" on each wing.

FLYING AT LUNCH
Unfortunately, I have not found a public park and I suspect the schools would call the police if I tried to use their field during shool hours.

STALL STRIP DESIGN
Very interested to hear how your stall strips work and see some pics. I'll shoot some pics of mine as well.

HOBBYZONE
I almost posted earlier to say that I have gotten very good customer service from Horizon Hobbies. (Understanding / polite accomodating.) What they lack, however, is a good product line manager on this side of the ocean. It would take all of 2 minutes to fly a Freedom slowly and observe that the tip stalls are violent and unforgiving - all wrong for a "Zone 1" plane.

Unfortunately, they have good customer service representatives but very few if any model airplane technicians / product line managers.

If the stall strips work well, I will see how high I can get in the organization to suggest a minor ECO to the wing.



Clint

Last edited by cbatters; 12-07-2006 at 05:19 PM.
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Old 12-08-2006, 02:57 PM
  #172  
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Fixed my boom but it was way too windy to fly this AM even in the dark. Will probably have to wait until Sunday to get some good flying conditions.

Any update on your modification / change in stall characteristics?




Clint
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Old 12-09-2006, 03:16 PM
  #173  
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Flew this AM with the modified wing. Very surprised how much a small piece of balsa affects the flying.

Stalls were much more controlled - dropped the nose nearly straight ahead - easy to recover. (An unusual thing to say about a Fedom stall!!) The only problem is that the trim of the plane didn't feel quite right - seemed to go nose up easily and pitch control was twitchy.

That said, I flew it around for ~ 5 minutes and thren brought it in for a safe landing.

I am going to add a half ounce of weight in the nose to compensate for the extra weight in the tail before changing anything on the stall strips. (I probably added 2-3 gr of weight in the tail which would require 12-18 gr of weight in the nose based on the length of the boom - 24" behind COG / 4" in front of COG)


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Old 12-09-2006, 06:12 PM
  #174  
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3 quarters in the tail - ~ 3/4 ounce

EDIT: 3 quarters in the NOSE - ~ 3/4 ounce

MUCH better balance / easier to control in spite of the rather blustery winds 12-15 MPH. Brought it in safely and will do more testing later if the winds calm down some. (I can handle the CHallenger in 10-12 MPH but not good weather for flying a new plane with balance / stall modifications.)



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Last edited by cbatters; 01-16-2007 at 02:12 PM.
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Old 12-11-2006, 03:45 PM
  #175  
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Flew it for about 10 minutes in light winds late yesterday afternoon as the sun was setting. Much better behaved. One stall flying downwind at reduced throttle setting - wasn't on the stick so it was probably caused by a puff of wind - easily recovered - only lost 25' of altitude.

Final summary:

Still believe that the Freedom is a bad choice for a new pilot. The Freedom has a violent snap-roll stall characteristic - completely innappropriate for a beginner Zone 1 plane.

My opinion is that they did not design in enough wash-out to accomodate manufacturing variations between planes. Other issues that may contribute to the tip stall problem and variations between planes.

o Bubbles in large decals near the wing tips cause premature tip stalling

o Cutouts in wing near fuse reduces lift near the fuse (wondering if this was in the original design)

o Untrimmed plastic mold projections on leading edges near the wing tips act like stall strips but because of the locoation cause violent tip stall

o Freedom wing generates too much lift near the tips which is why it has 3-4 degrees of washout. Someone in Marketing wanted short wings that would go into a small box. Engineers delivered but it doesn't have enough washout so many of the production units tip stall easily

o Tapered wing like Commander II, Challenger, Xtreme, Swift would be a more conservative wing design. (Less lift near the wing tips.)

o Any sagging in the wings (due to age or crashes) will tend to reduce dihedral and increase risk of tip stalls.

o Moving CG forward by adding 2 quarters in nose cone helps tame the stalls

o 4" stall trips on leading edge of wing also helps tame the stall behavior

o ACT should be disabled by taping over the bottom sensor and use the transmitter ACT switch as a low/high rate.


With the stall strips and extra weight in the nose, the plane flies under power about as well as the Challenger - but must be flown faster or it will stall. Should be rated Zone 2.

COMMANDER III
What Horizon Hobby should do is introduce a new ZONE 1 Commander III plane - same Commander Fuse / wing but with the Challenger three channel electronics. In beginner mode (with only one surface active in turns) it flies similar to the Commander II but adds pitch trims / control. In Expert mode, the turns are much sharper and require up elevator to maintain altitude. However, it is easier to fly and more forgiving than a Challenger. (Challenger requires active control input to recover from a spiral dive but the Challenge flown with a Commander wing will recover just be letting go of the stick.)



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