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Jun 09, 2019, 02:52 PM
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Lynxman's Avatar
I frequently scraped the tailcone on my 1/8 Tamjet F-16 ten years ago or so. Handled high alpha pretty well. Flew fine at 3600-3900 W with a Stumax 110 mm and 7,5 kg all up weight (16,5 lbs). F-16's have lifting boy designs so the wing is very much larger than the flat bits on the ends. Only thing I didn't like was the landing gear. Those diagonal spring struts were useless.
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Jun 09, 2019, 04:58 PM
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Thread OP
Thanks Kevin and Lynxman, I appreciate the info and advice.

The model is done for the most part. Been raining here most of the day so no taxi tests or anything.

My final weight is 16lbs 0.8oz. I could add 4oz behind the CG for wing tip missiles but not sure it would move the batteries forward at all. It looks great with them on so I may put them on anyways.

I included some photos of the battery placement and through the intake to view the fan. There is exactly 2.75" between the back of the batteries and the fan lip.

I really think the fan needs to be back much further but that would also cause other problems like longer motor leads and much harder fan access and mounting. But it also might allow for full ducting possibly (but that is also more weight).

Any more feedback is greatly appreciated.

Ken
Jun 09, 2019, 06:21 PM
Registered User
The fuselage interior layout is not optimum. You will suffer considerable losses in fan output (up to 50%). I know you know this, just saying.

Full ducting in and out of the fan is optimum. There are other F-16's with full ducting in and out. The retracts were mounted on either side (mains) and under the duct (nosegear), as were the saddle pack motor batteries.

Bit late to bring this up, but it's worth considering in future.
Jun 09, 2019, 08:53 PM
Registered User
Quote:
Originally Posted by KenM
Thanks Kevin and Lynxman, I appreciate the info and advice.

The model is done for the most part. Been raining here most of the day so no taxi tests or anything.

My final weight is 16lbs 0.8oz. I could add 4oz behind the CG for wing tip missiles but not sure it would move the batteries forward at all. It looks great with them on so I may put them on anyways.

I included some photos of the battery placement and through the intake to view the fan. There is exactly 2.75" between the back of the batteries and the fan lip.

I really think the fan needs to be back much further but that would also cause other problems like longer motor leads and much harder fan access and mounting. But it also might allow for full ducting possibly (but that is also more weight).

Any more feedback is greatly appreciated.

Ken
Ken,

Have you checked static thrust?

Sean
Jun 09, 2019, 09:32 PM
Registered User
Thread OP
Fan tested as advertised on my test stand. I will check in the model this week and see. Any suggestions for testing in the model. I figure that i will do it with gear down and gear up but trying to think of the best way. Any suggestions would be welcome.
Jun 09, 2019, 10:04 PM
HAL... Open the damn doors!
jfetter's Avatar
I wouldn't waste effort testing with gear up, in that configuration you are also moving through the air which introduces a completely new dynamic, so IMO it would be semi-moot at best...

Jack
Jun 09, 2019, 10:08 PM
Registered User
Quote:
Originally Posted by KenM
Fan tested as advertised on my test stand. I will check in the model this week and see. Any suggestions for testing in the model. I figure that i will do it with gear down and gear up but trying to think of the best way. Any suggestions would be welcome.
Ken,

An easy way is to put your scale up against the wall and have the plane push into it. Just ensure you cushion the nose so you don't damage it.

I use a fish scale with nylon rope and have the plane pull on the scale.

Neither method is perfect, but it'll give you a good idea of how much thrust is being generated.

Sean
Last edited by EDFjetpilot; Jun 09, 2019 at 10:10 PM. Reason: Spelling.
Jun 10, 2019, 05:51 AM
Registered User
Thread OP
Thank you Jack and Sean, I appreciate the advice. I'll get it tested around my work schedule this week. Hopefully fly on Friday or Saturday.
Jun 10, 2019, 12:17 PM
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demetrius's Avatar
Quote:
Originally Posted by KenM
Open discussion about my T-One F-16 Conversion.

The Model is 1/8.5 Scale
71.65 in length
46.85 wingspan

I ordered the model with lights and wingtip missiles, no tank or pipe. I did not get the model with servos but I will be using the same servos they off with the PNP model (BLUE BIRD BMS-A921 Digital Metal gear servos. The model arrived 1 day before the 8 week time frame in perfect condition and packaged very nicely. I was very happy with the quality of the model.

Here are some pictures of the model just out of the box, the fan system I chose to go with and the start of the conversion.

If I were to order again, I would not get the lights with the model, only the afterburner ring. Although the model is light, I removed the lights.
I thought about this model due to them having some very good looking models out now. I'm looking forward to see how she comes out!
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Jun 10, 2019, 06:28 PM
Registered User
Thread OP
It's a great model. If there was a way to mount that fan 5" farther back I think full ducting is possible.

Lets see what results I get with the open ducting and then I'll work on some CAD drawings for full ducting with the fan farther back. I have some ideas the more I've thought about it.
Jun 11, 2019, 06:45 AM
KingtechUSA
gunradd's Avatar
Looking forward to your progress Ken!!

She should fly well at that weight. The plane has a light wing loading and will high alpha really well like most F16s do. Let me know if you have any questions and I will try and help.
Jun 11, 2019, 06:27 PM
world's slowest builder
Air-Jon's Avatar
Some times simple things can make an improvement. Even simple fairing to guide airflow from the back of the batteries to the top of the intake bell can help and reduce the separation/turbulence behind the packs.

I'm sure it will fly just fine even if not fully optimized. The light weight of the T1 F-16 really helps. I was bummed when they never announced a factory EDF conversion for this F-16 as it is a great size for 127mm fans and batteries. nice size for 12S through 18S setups.
Jun 11, 2019, 06:36 PM
KingtechUSA
gunradd's Avatar
Quote:
Originally Posted by Air-Jon
Some times simple things can make an improvement. Even simple fairing to guide airflow from the back of the batteries to the top of the intake bell can help and reduce the separation/turbulence behind the packs.

I'm sure it will fly just fine even if not fully optimized. The light weight of the T1 F-16 really helps. I was bummed when they never announced a factory EDF conversion for this F-16 as it is a great size for 127mm fans and batteries. nice size for 12S through 18S setups.
If their was more interest in an EDF version they would do it. Its just hard to justify building custom ducting and different internals for only a few sales. I am watching with great interest on here to see how it comes out. If it does well and people show interest then I will talk to the factory and see if they can make some improvements for an EDF version. It looks like the inlet duct could be modified for much better airflow since a fuel tank is not needed. Possibly even longer rails to slide the fan back more for better flow to the fan and moving the batteries away from the inlet more.

But like I said if all this work adds up to 3 or 4 more airframes sold its not worth the effort for the factory.
Jun 11, 2019, 07:18 PM
world's slowest builder
Air-Jon's Avatar
I know you have been on the sales side of this business for a few years now Gunradd and you have a ton of experience and may be an entrepreneur yourself, but what you said is not really the way business works. A potential market is identified, and a business model is proposed. it is and internal business strategy to try and create/find market expansion. This is what a marketing dept does.

One person doing a build is not going to cut it. It can certainly be done but requires an internal entrepreneur within the company to go after a market, promote, and create addition business opportunity. You can't count on external evangelists in a market this size, but a rather small internal investment would probably be pretty low risk considering it is a matter of minimal redesign of a few bulkheads and the intake. That's not all that much work considering the resources already put into the project...

If a company made a really nice turn-key EDF F-16 this size...i'm sure more than 3-4 could be sold...particularly in Europe where large EDF is more popular these days. T-1s results will be the sum of their efforts regarding and EDF market. There is certainly a vacuum that could be filled with a scale jet of this size, if it's done well (Turn-key or ARF) if they are willing to put in the effort. I know you can help to plant the seed, but they will have to really get behind it if the project is to do well. I would happily sell my Yellow kit to fund one of these as it is really a better size and of course much more complete
Jun 11, 2019, 07:26 PM
Registered User
Thread OP
The inlet has a cut out at the top before it reaches that former. That is one thing that needs to be closed. There would then just need to be a connection piece to the fan.

The fan does need to go back. There was plenty of former there to move it back but i cut it off trying to make the model as light as possible. I know, not the best idea but honestly with some carbon plate, I could mount the fan to the plate and then extend it them forward to the same holes I have. I don't know if that makes sense but I'll draw it up in CAD.

The other thing I was thinking was keeping everything closer to the CG...I pushed it a bit much but I think it will work. I agree with Air-Jon but I want to see what happens first.

What effect will pushing the fan back and batteries forward have as compared to keeping it closer to the CG? Again this was just my thought process but this thread is meant to come up with a simple solution that is the easiest for the factory. Which could be just closing the duct that is there. Either the factory or someone else could sell the connecting duct, plenty on here could make it. We just need to stop telling the factory to make electric and help them solve how simply. They are turbine guys not electric. Just my opinion.


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