HSD 105mm F-16 EDF Jet

[Aros]

This thing sounds like an absolute nightmare, but I certainly admire your tenacity and perseverance!

LOL it can be!

Thanks man...It's a cool jet with awesome presence and size. Now that I have her where I want in the settings with the gyro I am hoping I can finally just enjoy flying her.

[Aros]

Sortie #4 started out and ended the same as #3.

My buddy was with me and we cycled the gear several times before takeoff and it cycled fine. Took off, flew around great...Another solid flight, I am finally quite pleased with how she's performing. Then I went to drop the gear and the same exact thing as last time. The nose gear and nose gear door was deployed but the main gear and gear doors did not. I cycled several times until I once again had to belly land on the pavement! Grrrrrrr!!!

When we went to pick it up and pick up the pieces, we tried cycling again and it cycled fine. What the heck!?!?

So my buddy, a Boeing engineer (quite helpful in these instances) asked me to try cycling under power. So I throttled up to about 50% and sure enough, the nose gear came down but the mains did not! Once I dropped the throttle to say, 20-30% the main gear doors snapped open like they were spring-loaded and down came the mains.

What in the world would cause that? We checked the radio for some weird erronous throttle/gear mix but there is none. Gear doors don't appear to be getting caught up on anything. So I will once again be contacting HSDJetsUSA. My fuselage is pretty beat up on the belly now and I feel like this is something haywire that came out of the box this way. My maiden flight I never retracted the gear but since I have this is been the deal. So bummed that I have her flying great and now the landing gear isn't deploying in the air. TWO belly landings now on the pavement and I'm not happy about it.

[Hugh Wiedman]

Sortie #4 started out and ended the same as #3.

My buddy was with me and we cycled the gear several times before takeoff and it cycled fine. Took off, flew around great...Another solid flight, I am finally quite pleased with how she's performing. Then I went to drop the gear and the same exact thing as last time. The nose gear and nose gear door was deployed but the main gear and gear doors did not. I cycled several times until I once again had to belly land on the pavement! Grrrrrrr!!!

When we went to pick it up and pick up the pieces, we tried cycling again and it cycled fine. What the heck!?!?

So my buddy, a Boeing engineer (quite helpful in these instances) asked me to try cycling under power. So I throttled up to about 50% and sure enough, the nose gear came down but the mains did not! Once I dropped the throttle to say, 20-30% the main gear doors snapped open like they were spring-loaded and down came the mains.

What in the world would cause that? We checked the radio for some weird erronous throttle/gear mix but there is none. Gear doors don't appear to be getting caught up on anything. So I will once again be contacting HSDJetsUSA. My fuselage is pretty beat up on the belly now and I feel like this is something haywire that came out of the box this way. My maiden flight I never retracted the gear but since I have this is been the deal. So bummed that I have her flying great and now the landing gear isn't deploying in the air. TWO belly landings now on the pavement and I'm not happy about it.

What a major bummer, your flight while in the air looked perfect too. Interesting the way the pilot decided to eject on landing, he took the entire cockpit with him for a little added protection. I guess HSD expects you to get some altitude before dropping the gear, then cut the throttle and wait for the gear to come out before powering up again, not exactly "by the book" technique though. Sorry to make lite of your experience so far, guess I'm so used to having happen that I tend to joke about it when what I really want to do is brake down and cry, after a few choice words though.

[Aros]

LOL like I say Hugh Wiedman if you don't laugh you will cry so might as well laugh. But like you, not before a few choice words have sprinkled the air.

I am very interested to hear what they have to say about it and if there could potentially be a fuse or part replacement. I am at a loss for what could cause this bizzare issue.

If it's not one thing it's another with this beast of burden!

[Porkster]

I bypassed all those dodgy little box’s and created sequences for the doors, gear and gear locks. It’s a lot of effort but worth it.
if your radio has that capability then it’s worth sitting down and working the sequences out.
great ‘plane but a lot of poor components and needless complex gear locks too.

[Aros]

I see what you are saying Porkster but for the money this bird should work as advertised. I shouldn't need to bypass anything, especially with their touted new control board. And being that this is my third model (V1, V2 and V3) I should expect it to work as it should especially since the other models didn't have this issue. Not aiming my frustration your way obviously, just stating how I feel about it. For a $1,000 foamie I expect everything to work as advertised without having to deal with the headache of rerouting electronics to work properly. Two belly landings on pavement really sours my mood. I totally get your point and I agree, the engineering could be much better. My hope is that HSDJetsUSA takes care of this issue in a way that satisfies me. I'm not asking for a replacement jet but I do feel something needs to be done.

[PaulZ]

Hi Aros sorry to hear this! What a weird one... I think you are right that this could be some issue with the control box. I had a similar situation with the mains not coming down while in the air. In my case it was one of the gear door servos not having enough power to open the gear door while there was airflow over it. I replaced both servos with Freewing ones and now it works perfect, Lol!

[Aros]

PaulZ Ah so the same thing happened to you with this jet? VERY interesting...That could be the problem then. We suspected it had something to do with the gear doors and not the gear themselves.

[PaulZ]

PaulZ Ah so the same thing happened to you with this jet? VERY interesting...That could be the problem then. We suspected it had something to do with the gear doors and not the gear themselves.

Aros, in my case I could see one of the main gear doors opening and not the other while I was doing my "gear check" fly over. However, sometimes both would not open as well. I had to slow the jet down almost to stall speed and then cycle the gear for the doors to open. So I knew it was related to week servos. It could be that in your case there is enough suction from the EDF that the doors both can't open when you throttle up, even on the ground - you may have even weaker servos.
I would recommend you test that - disconnect the servo linkages from the gear doors, position the plane gear down and let the doors swing open loose. Throttle up to full throttle and then drop the gear without any doors in the way. If they work then the gear doors is what causes the gear to not open and not some electrical glitch. Remember that the MFC has a current limiter (set to 1A) on the gear motors. If they struggle to open and reach that current limit the MFC will shut them off to protect the motors. So, when the gear doors are in the way an do not open, everything stops.

You can replace the servos with standard 9g analog servos, these are not HV servos.

[Aros]

Good advice thanks PaulZ ! I flew her again today and this time the gear deployed, but only after me chopping the throttle for a few seconds. Enough to activate the doors and get them out of the way. Breezy crosswinds but she landed softly on her feet!

[PaulZ]

All, check out this great video of the fairly significant CG change on the HSD F-16. This is why I use a gear-ele mix that puts some down elevator when gear is deployed...

https://youtu.be/APJfiHFjOKg

[Aros]

GREAT video! Really visually brings it home as far as how the CG shifts between gear up or down. I am at 175mm with elevator trim for gear up. I don't mind managing the sticks when the gear comes down because you have to be on the sticks (obviously) any ways to set up for the landing sequence. Nice visual representation.

[Hugh Wiedman]

Good advice thanks PaulZ ! I flew her again today and this time the gear deployed, but only after me chopping the throttle for a few seconds. Enough to activate the doors and get them out of the way. Breezy crosswinds but she landed softly on her feet!

Great Flight and Landing Aros !! Here's are real "off the wall" suggestion for your gear. Your gear switch servo "travel" on the 2 position switch is 100 to -100. Since it seems the gear doors are not opening under advanced throttle (for whatever reason I can't imagine), what if you try some different travel settings in the TX for that switch, say 110 to -110, or 100 to -110 or 90 to -90 then see if the gears work at throttle off and what happens when your throttle is at say 60% (or whatever it is that the gear doors don't open). There must be some "power" draw that's affecting those gear doors to not initiate opening and since this doesn't happen to everyone, either there is a slight difference in the "signal" from your TX as opposed to others that don't have the same problem. The only way you can change that signal in your TX is through the gear switch travel.

I'm sure that won't work and I'm sending you on a "wild goose chase", but then you never know.

[Aros]

Hugh Wiedman hey buddy I can always count on you to think things through, unorthodox or not. That is not a bad angle at all. Never considered travel settings...I just found out today that there is a function in the control box that can allow you to change the "speed" of the gear doors. I was told that not only does the speed of the gear doors change but potentially the "power" of them does as well. (News to me!) The more I hear from folks and the more I think about it, the more I think what is happening is that HSD installed weak servos for the gear doors that can potentially (in my case definitely) fail to open under certain higher RPMs, such as our bench testing of 50% power or higher where they don't deploy. When the RPM is lower, say 30% power, suddenly they work like gang busters and all is well.

I can repair my fuselage (again). I am not going to demand a new fuse or anything like that but I would like to think they will at least offer me something...Perhaps new replacement servos that are more robust? Thoughts?

[PaulZ]

Hugh Wiedman hey buddy I can always count on you to think things through, unorthodox or not. That is not a bad angle at all. Never considered travel settings...I just found out today that there is a function in the control box that can allow you to change the "speed" of the gear doors. I was told that not only does the speed of the gear doors change but potentially the "power" of them does as well. (News to me!) The more I hear from folks and the more I think about it, the more I think what is happening is that HSD installed weak servos for the gear doors that can potentially (in my case definitely) fail to open under certain higher RPMs, such as our bench testing of 50% power or higher where they don't deploy. When the RPM is lower, say 30% power, suddenly they work like gang busters and all is well.

I can repair my fuselage (again). I am not going to demand a new fuse or anything like that but I would like to think they will at least offer me something...Perhaps new replacement servos that are more robust? Thoughts?

Aros after analyzing what happened to both of us, I really think it is the weak gear door servos. The doors are right after the cheater inlet for the EDF and I bet they are getting sucked-in as the EDF rpm increases. The MFC setting you refer to is not to adjust "speed" at which the doors close but delay after which they engage. I don't think getting new servos from HSD will help as their 9g servos are not very good. I would recommend replacing them with some other servo make that have higher torque. After I replaced mine I now have 100% gear reliability.

[Aros]

PaulZ I am in complete agreement with you. I too believe it's the gear door servos without a doubt. I've already re-painted the scuff marks on the belly so I think I'll just grab some better servos and call it good. HSDJetsUSA wants me to take video of the issue but frankly it's not worth going through the dance just for a couple of servos, to your point, are not very good anyways.

[Hugh Wiedman]

Aros after analyzing what happened to both of us, I really think it is the weak gear door servos. The doors are right after the cheater inlet for the EDF and I bet they are getting sucked-in as the EDF rpm increases. The MFC setting you refer to is not to adjust "speed" at which the doors close but delay after which they engage. I don't think getting new servos from HSD will help as their 9g servos are not very good. I would recommend replacing them with some other servo make that have higher torque. After I replaced mine I now have 100% gear reliability.

Now that sounds like you nailed it PaulZ , the doors being sucked-in as the EDF rpm increases and 9 g servos without enough guts to break the suction. Impressive logic, you must moonlight for the NTSB in the series "Air Disasters".

[Aros]

Yes I concur!

[Hugh Wiedman]

If the gear doors shut perfectly flush and create a vacuum from the cheater inlets in the well, would it make any sense to drill a small hole in the doors for a vent, even if going to a beefier servo? Might relieve some of the pressure on that as well. I know the last thing you want is ventilation holes in the gear doors, but if it helps maybe that's better than having no landing gear when you need it most. You have to excuse me from offering any silly advice in this thread even though I don't have this model, but I want one BAD but only fly off of grass now so I'm stuck living vicariously though those of you that do have one! I think HSD is discriminating against those of us on grass, I mean flying RC, not want you're thinking.

[Aros]

Well I'm not sure on that Hugh but this is the email I got from Support:

Actually, I don't think that's the issue (gear door servos being too weak). The EDF version has very small holes into the gear well (for wire access) and it would take a lot more suction than what the stock system can put out to force the doors closed. The turbine version has measurably more suction and it uses the same servos and doesn't have this problem. Even when this happens, the gear legs push the doors open.

I would suggest that you confirm that both your servos and gear are operating on 7.4v. 6.0v could cause this. After that, confirm that your door delay is set to zero. Gear motors should be set to 1000mah.

Joseph
Tech Support, HSDJETSUSA

But if PaulZ upgraded his servos and now the gear works perfectly, that heavily suggests servos being the issue. I will have to look at the controller settings to see if the servos and gear are both operating on 7.4V. But this comes configured from the factory as I haven't touched any of those areas. Not sure about those other parameters...I'll have to take a look after work.