HSD 105mm F-16 EDF Jet

[Aros]

I thought there was a thread on this model but I couldn't locate it so I am creating a new one. This is for anyone who owns, have owned or is thinking of owning the HSD 105mm F-16. I have had two Arctic Camos and just pulled the trigger for Arctic Camo #3. The reason I bought a new one even though I struggle with finding an open, unobstructed space to fly it is because this new version has an upgraded power system which greatly increases the thrust/weight ratio over former versions. It's a great model all-around but definitely a heavy bird. The old stock power system I always felt was inadequate. So my Pucker Flights were always made worse feeling like I had to keep her at 3/4 to WOT just to keep from feeling like she wanted to drop.

PaulZ I know you recently maidened yours and that it went great. That's awesome! As I am always in the hunt to maximize mastering this model I am always curious to hear what others have found as successful for them such as CG location, throws/rates, etc. Please (anyone) do share!

I may opt to drive the 2 hours or so to a RC field in Eastern Washington. There, it's wide open with no obstructions. My dream. I may maiden there (or somewhere over there that's wide open with nobody around). Looking forward to it!

[Lcacing]

I got my HSD F16 about a month ago and now have almost 40 flights. The first time I was introduced to the HSD F16 was late last year, a flying buddy got the older version and upgrade the power system a 110 mm Hacker fan, not sure the motor rating, he struggled getting the bird to fly the way he wanted, he was using the elevator/throttle mix and during flight, it would trim correctly but on landing it would ballon up. His solution was to keep bringing the CG forward, the plane would just fly like crap. We would talk about it and discuss what to try next, from what he described the issue was the change in trim between power on and off.
Once we decided to remove the elevator/throttle mix and moved the CG back to around 165mm, the F16 came to life, the crazy changes in AOA during landing went away, as you mentioned, the original stock system was really underwhelming so I stayed away not wanting to spend and extra $500 plus on new power system.
Once the new version came out with the new power system I was sold. I did do a few changes to the configuration. Decided to go with tailerons only and flaps, maiden flight CG at 160mm but did have to remove foam to move the batteries back, HRB 6000. I’ll post link to maiden flight.
Since then I’ve moved the CG to 170mm, reduced the exhaust to 90% FSA (went form 105mm to 85mm) that improved top end speed and 1/2 to 3/4 throttle power band was better. Amps draw did go up but flight time was not effected because cruise speed was better just above 1/2 throttle vs 3/4 before exhaust reduction.
I also could not get the brakes not to completely lock up so I cut the brake plate in half, now at 100% travel the brakes bring the plane to a smooth stop.

https://youtu.be/sHz4qzBXjGw

[PaulZ]

Hi Aros I also started a thread for the HSD F-16 a couple weeks ago: https://www.hobbysquawk.com/forum/rc...pnp-12s-thread

But we can use this one...

[PaulZ]

I have my CG right now at 155mm and found it flying fine. It think this is because I left the stock throttle-elevator mix as it was setup in the HSD box. Now I am hearing it is not needed so I think I will try to see how it flies without the mix and the CG back to 170mm.

[Aros]

Wow Lcacing , 40 flights already? Nice! Great landing on that maiden btw! That's as good as it gets...Well done. As for the FSA to 85mm, how did you achieve that? As for CG, I wracked my brain especially with my first one, trying to find that sweet spot. Was driving me nuts. I finally settled around 165mm. I always found her very sensitive to throws so I was flying my last one at like 30% ailerons...Coupled with the Cortex gyro she finally felt locked in but I was never truly comfortable due to the lack of thrust/weight ratio. Where I fly this model I have to come in on a high approach due to the trees lining the parking lot threshold. Which always creates for a bit of a challenge for those perfect flared alpha touchdowns. I lucked out more than a few times when I would plop her down hard at times but the gear never failed me. I dream of flying this bird in an open area with a low, easy approach. At least the parking lot is 1800ft which is a huge help for those high approaches.

[Aros]

Hi Aros I also started a thread for the HSD F-16 a couple weeks ago: https://www.hobbysquawk.com/forum/rc...pnp-12s-thread

But we can use this one...

Ah geez man sorry I completely missed that and I was using the search feature as well going several pages deep! Doh!!

[Aros]

I have my CG right now at 155mm and found it flying fine. It think this is because I left the stock throttle-elevator mix as it was setup in the HSD box. Now I am hearing it is not needed so I think I will try to see how it flies without the mix and the CG back to 170mm.

Ah, interesting. I never have used that throttle/elevator mix, or maybe I did early on once but didn't like it. I think all things being equal, the sweet spot is between 165-170mm for most folks. I tried 178mm or something around there and holy crap she was a handful! Did not like that at ALL. 155-160mm was to heavy for me (solid in the air but landings were more of a challenge) and so 165 just felt like the right spot. It will be interesting if I feel the same way with #3.

Where are you guys liking your rates and expo?

[Lcacing]

Wow Lcacing , 40 flights already? Nice! Great landing on that maiden btw! That's as good as it gets...Well done. As for the FSA to 85mm, how did you achieve that? .

Thanks!!! I made the thrust tube about 6” long tapered from 105mm to 85mm. I then just taped to the inside with aluminum tape, I wasn’t sure if it was going to work so didn’t want to put too much effort. I decided to use 90% FSA (85 mm) due to the little research I did, from what I gathered 90-80% is typically the range the exhaust should be. If I ever get bored, to find the best FSA % I would have to make a few tubes ranging from 85 to 80 one milliliter at the time and test fly each one of them. I can bet my complete R/C collection that I’ll never be that bored.

The math is simple or can use the online FSA calculator. You will need the ID of the fan shroud and the OD of the center fan hub.

Pi x Rsquare(ID) - Pi x Rsquare (OD) = 100%FSA ( find R to get diameter)

[Aros]

That's great...My LX SR-71 Blackbirds had thrust tubes as well and they helped immensely with that model. To confirm, you have the new V2 version with the half metal S-EDF?

I'll give it a go first without a thrust tube and see how I like it. I figure I will have a good sense of the power performance increase based on my experience with the old V1 versions. If I find myself still craving a bit better throttle output at the 1/2 - 3/4 power range I will give it a try.

[Lcacing]

Aros. Yes this is the new version S-edf and MFC 2085

[Aros]

Roger that. So thrust tube aside, how did it feel stock overall?

[Lcacing]

Never seen in person how the older version F16 performed but a flying buddy has the Super Viper with the stock V1 105mm and then upgraded to the S-edf. Big noticeable difference. With that said, the HSD F16 with the new power plant ,vertical performance is quite good, not a speed demon, I clocked mine around 108 mph, it just edges the Freewing F16 (I had one and sold it to get the HSD).

Mine is set up for tailerons only, pitch at 34mm, roll at 38mm
flaps 14mm and 25mm. Caution at full stick travel at corners (max elevator and aileron) the servos will bind.
Another simply modification I did was to make the ventricle fins removable using Freewing F16 weapon attachment hardware, easier to transport.

[Aros]

Nice touch on that ventral fin mod! Those can definitely be vulnerable during transportation. Without visual reference it does seem like that's a lot of throw? Do you prefer more throw with your jets? Maybe it's not at all...Not sure why it strikes me as a lot. Also - and thanks for answering some questions - what made you decide to go with tailerons over ailerons?

[Lcacing]

Is actually a bit less than manual with 25% expo. The throw for roll(tailerons) is actually not as bad, the surface is smaller so more throw is needed. I do like to do some
high alpha flying and even with full up elevator the F16 just chugs along, very predictable stall, nose just drops, add a bit of power and it keeps flying.
The reason for using tailerons, if it works on the full scale it should also work on the model. In fact I did the same with the Freewing F16, 18 and F14. Full span flaps on all and tailerons. I did add small amount of Up only on the ailerons ( f14,f18) to compliment the tailerons for added roll input.

I do have conditions set for normal configuration in case of emergency ie loosing one elevator half.

flaps do reduce the take off distance, specially if flying off grass.

[Aros]

Nice, I've only ever flown traditional aileron/flaperons/elevator...I wonder if I tried your setup what I would think? I definitely know I prefer a lot less throw than the manual calls for, especially roll.

[PaulZ]

Aros In terms of rates and expo, I really like the model as follows:

Ail: 70, 20% expo
Ele: 80, 15% expo
Rud: 90, 20% expo
After some more analysis and conversation I'll leave the stock TH-ELE mix. My plane flies really nice and level at all throttle levels so this thing is doing its job. Again my CG is closer to the front at 155mm. I also use AS3X gyro and have that dialed in pretty well now.

[Lcacing]

How does it fly inverted, always wondered how it would react with the throttle/elevator mix on.

[PaulZ]

How does it fly inverted, always wondered how it would react with the throttle/elevator mix on.

With only a slight touch of down elevator. I am also surprised that the TH-ELE mix does not impact inverted flight more.

[Aros]

Thanks for posting that PaulZ ... Looks like you like yours more reactive/responsive on the sticks than I do. For me it's mainly because of the area I fly is a lot of Pucker Factor with the buildings, trees, poles, etc. So I like to feel that she's as smooth as possible in all axis' throughout the entire flight envelope...Rolls are pretty scale looking, still maneuverable enough to get out of a jam if need be. I suspect if I had the unobstructed open land to fly her that I would love, I would open up the rates more. As for the throttle/elevator mix, I think I did use it on my first one for a few flights but shut it off. I think it's because I read enough about it from others that I agreed it was just one more mix that could create an issue if something went wrong...Isn't it also a CG issue when the gear is retracted? I can't think offhand what it's main purpose is for?

[Aros]

Initial tracking said it would be here Friday. Now it says Monday. Dang tease.