mauryr

Wow, that does sound a little heavy. What is the kit's original weight? Just barebones airframe + landing gear, anyone know?

heraldoboldrin

Sound correct for me, Mine has 26.5Kg without smoke, with P300, pylon and wing tip missile.

FenderBean

So funny to see people say a 120 inch long rc jet is heavy at 62lbs LOL

Viper1GJ

My Feedback: (20)

Fender,

Don't have any numbers yet but my Avanti XXL is at least 8-10 lbs lighter and it is bigger than the F-16. The BVM 1/5 F-16 is also lighter by a lot and lands much slower. My F-16 is stock, no external stores, smoke system, Tailored Pilot, and a servo for canopy in place of air cylinder. I am using a B300F but it is not that much heavier.

I was shocked to see the final empty weight. I had hoped for 8 lbs less based of what I was told during the build. I think possibly the issue was folks wanted to avoid LTMA1. Anyway it flies great, just lands faster than I had expected.

Gary

FenderBean

well SM seems to be heavier than most, my comment was more along the lines of what weights were just a few years ago. I completely agree I think the large model requirement has driven the larger planes to get lighter. It's such a pain to do and the requirement to redo the sign off every year is just ridiculous in my opinion. It's cool if you have guys at your field but most don't and having to do things at events or traveling long distances to get it done is why most choose not bother I think.

Viper1GJ

My Feedback: (20)

LTMA1 is not that hard once I understood how it works. Self inspection and sign off to fly two times. Then just have 2 CDs sign the form and send it in. I copy the form and carry it in my tool box. Each time Im at a meet or fly in and can get 2 CDs to sign it off gain I send it in. Keeps the waiver current with out having to schedule an "event" once a year and it never goes non current. Keeps everything legal. Will have to start with the Avanti XXL when I get it going this year.

Just re read your Avanti XXL thread, good tips, thanks. By the way how much did you Avanti weigh and did it fly well at CG 330mm? Thanks

Gary

heraldoboldrin

I am in Brasil, we don't have weight problem here.. i just think skymaster could think to do their jets a litle lighter...
For example.. i have an A10 from mibo.. with more than 200 flights.. amazing jet.. the A10 from skymaster is smaller and much havier with the same setup.

FenderBean

Gary I don't remember off hand what mine was for weight I want to say low 40s. It's not a hard process but the intent is complete the full inspection and flights over every time you renew. Unless I'm reading it wrong.
That's why I like to do the builds, I learn from people posting in the thread and then others learn if they get the same jet. I just wish I could do more builds, but they are not cheap and it takes a while to save up or deploying for 9 months lol
I went with the recommended CG and it flew fine, def need as much flaps as u can get or the jet doesn't want to come down.

Digital Pilot

So I've been tossing the idea around of putting the KT250 in the tail of the F-16. This would mean putting as much equipment as I can in the nose section. This would eliminate the pipe and save some weight.
Can anyone give me feedback on CG of the factory setup? I'm interested in the amount of weight and where its needed to CG.

Thanks all

mauryr

I don't know the exact figures, but I was told the 250 (which is actually going to be the 260!) should weigh more than the 210, but of course less than the 310. I suppose somewhere around 2 kg maybe.

Digital Pilot

Correct on the 260, was not sure if that was released info yet. The tail mounted setup would be super easy to do and save some weight. I would make a light weight tray just past the mains to put the turbine electrons on and maybe push the lower tank back on the CG location as well.

heraldoboldrin

MIne F16 use 3 batteries in front of the turbine (p300), the light battery inside the fin, and i sitll need some weight in the back.
maybe your idea will work.. if you install the battery in the front.
But i think wont save to much weight and you need to do a new turbine support.

Digital Pilot

Turbine support is not a problem, Will design and table rout the parts needed and Hysol in place. Removing the larger Tam pipe and large bypass will save some weight , not sure how much though..

Viper1GJ

My Feedback: (20)

Digital,

Been pondering your idea. It is possible. I am also a scratch builder and kit basher. You can do it but here are some things to consider.


Here is what you have to work with at the tail end. The nozzle is non structural and twists on key hole slots. Turbine mounts will have to be forward of the aft former unless you build mounts aft of the rear former. The weight you save by removing the pipe will be offset by the weight of turbine mount structures.



The CG is approximately where the center former is, about where the first "S" is on the fuse side. As you can see there is no room here for more fuel. You can put it aft of the former like I did with my homemade smoke tanks. Fuel would have to where the center tank fits now or aft of the center former. The saddle tanks hold about 100oz each. For a 250 engine you may want more. I am using a B300F.


More fuel can go here. My homemade smoke tanks are aft of center former.



Here is the biggest issue in my opinion.

In this side view the CG has to be about where the first "S" in "States" is. If you look at the photo you will see that about 2/3s of the total airframe mass is aft the CG: aft fuse, wings, stabs, fin, dorsals, all servos, and in your case turbine and mounts. All of this weight must be offset on the seesaw in front of the "S". I don't think you have enough stuff to cram in the nose cone and forward fuse to overcome the mass the aft mounted turbine with out additional ballast.

Here is current example that suffers from an aft mounted turbine and the resulting excess ballast in the nose to offset the turbine weight in the rear.

This is my scratch built Sabre XLT. You can read about it here: http://www.rcuniverse.com/forum/rc-j...sport-jet.html

It suffers from exactly this problem. The turbine is in the rear to "save the weight and cost" of the pipe. The CG is exactly in the middle of the fuse. This jet has to have about 6 lbs of lead in the nose cone to offset the rear mounted turbine. So much for saving the weight of the pipe. Unfortunately I flew it through a tree two weeks ago. In the rebuild I am moving the turbine to the center and installing a Tam pipe and removing all the lead in the nose.





The rear mounted turbine can be done but you need to do some calculations and planning first to see if it will really do what you want.

Good luck, keep us posted on your progress.

Gary

Digital Pilot

Thanks for the info Gary.. I will do some weight and balance figures before i make the decision.

Levi Wags

Gary I just weighed mine and she came in heavy at 28kg (62 pound) dry. I have lots of goodies in there plus a P300, but nothing that I'd like to go without.
Digital I wouldn't be concerned about weight. I think these bigger planes fly more scale when they are on the heavy side. For example the Skygate Hawk built light looks funny landing at 50kph and floating on like a boomerang.

Viper1GJ

My Feedback: (20)

We are right there together. You should be fine. Where is your CG? Keep us posted on your progress.

Gary

Levi Wags

Ok CG update. Sounds similar to yours Gary. Mine is 265mil without any ballast. Fuel and smoke empty but header full. Took 300 grams in the tail to get it back to 280. I may add a little more but I think with the rearward smoke tanks this is close to a good starting point.

Gary have you flown with new smoke tank config?

Viper1GJ

My Feedback: (20)

Levi,

Just now got connections done and fuse halves mated back together. Have to ground test all functions and fine tune all the Powerbox programming.

I plan to start with empty fuel and smoke, air trap full CG of 290mm. Then I will check CG with full fuel, no smoke fluid, full fuel and full smoke fluid, and empty fuel and full smoke. I want to know CG range incase of forced landing with worse case trapped fuel or smoke fluid. Hoping for 270-290mm with any configuration

Then comes ground engine runs, taxi tests, and range checks. Next test flights scheduled in three weeks. Will keep you posted.

Thanks,
Gary

Levi Wags

Cool mate I'll do the same. Once I did land my 1/6 F16 with rear smoke tanks half full. It was fairly tail heavy. All good once I realised though, I just needed more speed on landing than usual to prevent A of A getting too steep.

Viper1GJ

My Feedback: (20)

Good looking jet Levi. For such a large jet it is one of the most densely packed models I ever worked on especially through the narrow passes around the fuse joint. Lots of stuff goes through there at least in my case. Good luck on your test flights.

Gary

Digital Pilot

Good day all. has anyone replaced there lighting controller with a UniLight unit? Im wondering if the output voltage is the same as the Skymaster ones?

Thanks

Viper1GJ

My Feedback: (20)

Update on winter mods.

I installed a new Powerbox SRS Royal and PowerBus servo system over the winter. Also installed the new smoke tanks and dual output pump and CB Elektronics IAS sensor to the PowerBox SRS for gyro gain adjustment. All installation and testing is now complete. Test flights are scheduled for 31 Mar.

Some photos:


Output mapping, PowerBus Adaptor, all hooked for initial tests, dual receivers, pre-fuse mating testing



Smoke tanks installed, plumbing everywhere, ECU programming, new equipment and battery tray


PowerBox SRS installed, testing steering gyro input, sequencer programming, Skymaster strut service tool mod, Finished.

I found the nose strut pressure low so after servicing with air the jet no longer has negative pitch when full of fuel. This will help take off rotation. The overall weight was reduced by 1.5 lbs, mostly servo wires and tail ballast. Now empty CG is 285mm from LE and weight is 60.5 lbs. Take of CG is much better with new smoke tanks caring weight to the rear of the OEM smoke tank.

Hopefully these improvements will eliminate the gear down glitching I had and overall flight quality. We will see.

Gary

rbxbear44

My Feedback: (86)

Great work Gary! Hope to see you at some point before SJS.

Rex

Digital Pilot

Lights, Anyone using a different controller?