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Old Jul 01, 2010, 10:34 PM
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Slaanesh's Avatar
Melbourne
Joined Feb 2009
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I was hoping that this would be a good EDF to start on - I've only flown regular low-wing warbirds previously.
All this talk about pitching around gets me a bit nervous but it's all part of the hobby!

So why does model pitch up so violently?

I've been reading the HE-162 thread - this model has it's EDF mounted on it's back, so it's thrust line is somewhat higher than a regular airplane. On hand launch, it tends to pitch down - which makes perfect sense to me.

The TA-183 seems to have a thrust line which is lower than a regular airplane, so this helps explain why it tends to pitch up.

The more thrust being applied the worse the effect of the pitching - especially at low airspeeds ie. take off.

Once the airplane is at speed, the pitching effect shouldn't be as bad.

I'm thinking that launching the TA-183 at around 70% throttle aimed a few degrees down would be the best approach (if you are hand launching). Let it get air speed and then start climbing.

Conversely, the HE-162 is best if launched at around 70% throttle aimed slightly upwards as it will naturally try to go down into the ground.

I think both models launching issues could be partially resolved by modifying the thrust line slightly.

In the case of the TA-183 have the exhaust aimed slightly down (perhaps 2 degrees).
Likewise the HE-162 could have it's exhaust aimed slightly up (again 2 degrees or so).

I actually have both models, though unflown - and in fact not even built.

Any opinions on my suggestions?
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Old Jul 01, 2010, 11:04 PM
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Canberra Australia
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I think its all to do with the wing and tailplane incidence. On both the Alfa MiG15 and Huck this is set by where the builder glues the wings and tail feathers. You could get it right, but sometimes you could get it wrong too.

My Alfa MiG15 maiden was a exciting affair. It basically leap off the ground, did a tight half loop at about 3m altitude, and then was momentarily heading back towards me inverted at full throttle. I was able to roll it out and it continued to climb away. So despite really working hard to get all the incidences right, it still needed a bit of down trim. Once trimmed it flew wonderfully and each takeoff (ROG) was a gentle climb away - beautiful to watch.

If I was to maiden another I reckon I would hold a little down elevator and gently back it off to allow the plane to ROG.
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Old Jul 02, 2010, 10:29 AM
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DeKalb,IL
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I think I was the cause of the vertical take off. As the huck was picking up speed I could tell she was not going to lift off the ground on her own. so I applied a little up elevator Once the huck rotated she was flying level with a slow climb for a second. Here I should of just applied a little more power to gain airspeed but I first applied up elevator then power and that was when she went vertical. My plan for the next take off is to pickup a little more ground speed and lift off and level out with a slow climb I think I'm going to leave the CG alone for know I think it is in a good spot for right now. I did use the the manufactures method to balance the huck with the nose slightly down pitch. I do have a great planes CG balancer but it is out on loan but I'm going to pick it up tonight so i have it on hand.

slaanesh and caseysp

I agree with the both of you that putting in some thrust lines could help and a slow level climb is needed for take off. But I keep looking back at my elevator and keep think do I have the incidence set correctly. When I was assembling the huck and got to the point of installing the elevator I read the procedure over and over again and said to my self there is not a lot of information here. I feel I've got it very close because once the huck was in the air it only took 3 to 5 clicks of down elevator and she was flying level. The one thing I didn't like was the quick response of the ailerons. I'm thinking it is because of the swept back wings so I think some expo will help this. As a side note I keep thinking about the flight and how awesome the huck looks in the air!
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Last edited by BadLemon; Jul 02, 2010 at 10:54 AM. Reason: left words out
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Old Jul 02, 2010, 04:21 PM
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USA
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Your experience is very much on par for that model. Like all Alfa scale models,, it demands speed. Even with the wimpy system mine had, it was quite fast on step. Being soo small, it was quite thrilling to fly every single time. Consider the layout,, with power unit down low, and drag items up high... When throttle is applied before the wings and tail feathers have accelerated,, the power unit(fuselage) will surely pitch UP.

That was only my 3rd successful EDF and I think it might be a little easier now days with a few more jets under my belt.

It is quite amazing how well that little jet glides. Upon slowing down, it settles in quickly,, perhaps too quickly. However,, that first approach is quite startling as you have noticed!

I get the post flight shakes just thinking about it...
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Old Jul 03, 2010, 02:14 AM
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Slaanesh's Avatar
Melbourne
Joined Feb 2009
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Handlaunching HE-162 and TA-183

Just wondering about a solution to hand launching the HE-162/TA-183.

As an example for the HE-162 (the same could be applied to the TA-183).

The stock HE-162 comes with two aileron servos - so I thought instead of using the y-splitter why not install them as flaperons?

ie. On take off (lots of throttle) use the flaperons with about 15 degress down to avoid the sudden pitch down.

Possibly the TA-183 could be the same, though instead of using them as flaps, using them to apply additional reflex.

Once in the air, switch them back to neutral.

Any thoughts?
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Old Jul 03, 2010, 09:41 AM
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DeKalb,IL
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That is interesting but I'm wondering if that would cause the huck to pitch up even more using flaperons. the way I see it the +5 degrees in the ailerons gives stability in to form of down force on the wing. But I could be wrong and probably am. I was looking at Kurt Tanks final design that came from the huck concept and it looks like he lengthen the fuselage and shorten the tail of the plane. I was thinking did he do this for stability. If so did they have the same problem as well of the huck pitching up. This made me think is the problem the tail moment and elevator and does this create too much control authority to the pitch of the aircraft? Sorry I may be over thinking the design of the huck but I really like the uniqueness of this plane. I know a lot of people think she is ugly but she has style of her own. I'm thinking of ordering another kit to have around and I have buddy that wants to build one as well. How cool would that be to have 2 or 3 huck's flying at once. Lastly if you look to the bottom of the page at the similar threads you will see a thread Steve Neil TA-183 Huckebein. The kit is a fiberglass fuse and foam wings. Does anyone know anything about this kit and if it available?
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Last edited by BadLemon; Jul 03, 2010 at 09:47 AM. Reason: more words left out
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Old Jul 03, 2010, 12:33 PM
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I think the instructions on the ta183 tell to add a slight amount of reflex to the ailerons in the neutral position. This is for pitch stability, and reduced tip stall tendency. As for the pitching up, it has alot to do with TOO MUCH THRUST and NOT ENOUGH AIRFLOW OVER THE WING AND STABS. Once the airframe is flying in concert with the fan airflow, everything is neutral. Its when the thrust down low is more than the airflow over the wings and stab that the upward pitching moment introduces itself. Yes, exactly like the me262 with its low thrustline.

Even with the low power mine had, it still pitched up a little on launch. That little jet requires a hard flat throw, or a longer take off run to minimize the upward pitch.

With your higher power setup, it might help to add a throttle/elevator mix. Although at speed the amount of down elevator mix needed would decrease a bit compared to the amount needed while accelerating.

Oh, and another thing to consider,, that giant 2100 battery is up high, fully above the thrustline. It will contribute to the upward pitching on acceleration.


Thrustline down low + drag and weight up high = upward pitching upon any acceleration. Just the nature of the design.
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Last edited by topforce; Jul 03, 2010 at 12:39 PM.
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Old Jul 05, 2010, 07:20 AM
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NY, Rochester
Joined Oct 2003
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Quote:
Originally Posted by CaseySP View Post
I think its all to do with the wing and tailplane incidence. On both the Alfa MiG15 and Huck this is set by where the builder glues the wings and tail feathers. You could get it right, but sometimes you could get it wrong too.
The Huck and the MIG 15 were known to have the wrong incidence. This most likely was factory intended as the powerplants were underpowered when these came out years ago. We all moved the batteries forward some, threw them level and not upward - but yes, by the time we realized this all had banged in noses
regards, Chris
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Old Jul 06, 2010, 09:59 AM
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DeKalb,IL
Joined Dec 2008
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To all

Well no flying this weekend the weather did not corporate, had some rain but the winds was the problem. From Friday to Monday we had winds from 18 to 35 MPH! I did check the CG on the Huck and it was a little nose heavy so I moved it back a little. I also read the flying instructions about launching the plane to keep it level and build up speed as fast as possible. I also read at at low speed the Huck will act like it is tail heavy and could pitch up so be ready to "push" apply down elevator until the plane picks up speed. So this confirmed that my vertical take off was my fault and I need to apply the "KISS" factor! Keep It Straight and level Stupid! Hey that works too! So hopefully I can get the Huck out sometime this week but the weather forecast is showing rain and thunder Storms every day this week, not good.
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Old Jul 06, 2010, 03:52 PM
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It would be nice if somebody would make a 70mm size EPO foam huck. I find the little jets a bit less enjoyable.
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Old Jul 06, 2010, 04:39 PM
skunkworks
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United States, CA, Clovis
Joined Apr 2008
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Quote:
Originally Posted by topforce View Post
It would be nice if somebody would make a 70mm size EPO foam huck. I find the little jets a bit less enjoyable.
Now that would be very cool.
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Old Jul 06, 2010, 04:43 PM
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BadLemon's Avatar
DeKalb,IL
Joined Dec 2008
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Yes

I would be nice If you look at the bottom of this thread you will see a window marked similar threads. In the window look for Steve Neil TA-183 Huckebein. This kit was a 90mm kit sold several years back but the designer sold the molds to a person in Texas and he was going to sell them but never did. And nobody seems to know how he is and what happen to him. To bad too the fiberglass fuselage looked really good.
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Old Jul 11, 2010, 02:28 PM
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DeKalb,IL
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Update to all

the weather finally cooperated on Thursday or at least for 1 more flight in then the winds started up again. Like I said I checked the CG and left it alone the only other thing I did was put some expo in the aileron@10% and elevator@15%. Takeoff was much better but she still climb out pretty fast. Pitch and roll was not as sensitive as before and I felt I had much better control of the Huck. After about 3 minutes into the flight a crosswind started up I still flew for about 2more minutes and the winds increased so I setup for a landing. I tried to slip her in but the Hucks ability to glide kept the speed up and as I was bleeding off speed she got hit with a good cross wind. The next thing I knew the plane skipped off the ground and was coming straight for me. Some how I got her back under control and landed it as I was running backwards all in a second. We hung around at the flying field to see if the winds would die down but the just got worse so no more flights. I did get a video this time see attachment!
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Old Jul 11, 2010, 02:30 PM
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DeKalb,IL
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Sorry the video didn't attach I'll get it figured out!
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Old Jul 12, 2010, 09:45 PM
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Melbourne
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Thanks for the update BadLemon. Did you hand launch your Ta-183?

My idea about flaperons on the Ta-183 were really more inspired by using them on a He-162, which has the opposite problem - high mounted engine vs low mounted engine.

I've been watching videos of He-162 launching and they always seem to dip considerably when first taking off. No big deal really, especially if you are expecting it.

I've watched the Alfa Model Ta-183 hand launch video many times and I can't see any bad launching tendencies. Obviously the pilot (who I think is the Alfa Model designer, Antonin) either compensates straight away or is flying on a brushed motor version which is not exhibiting any bad tendencies previously spoken of.
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