YC 14 Winter Project

[Burnhard]

Days are getting shorter so I have been considering what to do over the next six months. My thoughts have been circling around a Boeing 727 as my first airliner but then I stumbled across the Boeing YC 14. I always wanted to have a cargo plane and this one looks strange enough to get some attention on our flying field.

I am thinking of a twin 70mm edf setup with retractable gears and a nice large cargo door for dropping stuff.

As a start I have ordered the plans for some paper models. However, I just noted that these do not have any formers (wondering whether it is just a round fuselage). Will do some testprints tomorrow to figure out the right size.

 

[Mr NCT]

I like it! Fuselage looks kinda egg shaped.

 

[Burnhard]

I like it! Fuselage looks kinda egg shaped.

I have been looking for some cross sections but with not luck so far.

 

[Mr NCT]

It kind of looks like the AN-72

 

[Burnhard]

Found some high level plans with a frontal view. That should be good enough to start. My plan is to start with one engine nacelle to get the size right for a 70mm edf. That will then dictate the scale for the whole aircraft.

 

[L Edge]

Are you going to explore the "blown flaps"?

 

[Burnhard]

Are you going to explore the "blown flaps"?

Very good question! Not sure whether I fully understand the concept. On the pics I have seen it appears that the fan is blowing over the wing. Is it just the case that the fan is blowing over the flaps or is it when you deploy the flaps, that part of of the fan blows under the wing and against the flaps?

Looking at the below picture, I am going to try the top version.

 

[leaded50]

main part of fuselage is round yes.

 

[L Edge]

Very good question! Not sure whether I fully understand the concept. On the pics I have seen it appears that the fan is blowing over the wing. Is it just the case that the fan is blowing over the flaps or is it when you deploy the flaps, that part of of the fan blows under the wing and against the flaps?

Looking at the below picture, I am going to try the top version.
View attachment 245903

It is the top one. YC-10 was designed for a STOL. Now a much faster airflow over the top that gets joined to the bottom air so you improved the lift.

 

[Burnhard]

main part of fuselage is round yes.

View attachment 245907

This one seems overly simpliefied. The above seems to indicate a mild egg shape.

 

[Burnhard]

Done some calculations. Given the size of the fan, the model will have a length of around 142.5 cm and a wingspan of around 139.6 cm. This is about the size of the Seaduck. Will start printing plans tomorrow.

 

[L Edge]

When I was in Tucson, Arizona visited PIMA air museum and saw the YC-14.

 

[Burnhard]

When I was in Tucson, Arizona visited PIMA air museum and saw the YC-14.

Can you remember whether the fuselage was a circle or egg shaped?

 

[Burnhard]

Printed the plan for the first nacelle today. That is eight sheets of A3 which cover what was once one sheet of A4.

 

[JonQ]

It kind of looks like the AN-72
View attachment 245897

Except the YC-14 came first. The soviets just copied, as they did with most everything else.

 

[leaded50]

round main fuselage shape, but more egshaped in front.:

perhaps best 3D view:

 

[Burnhard]

Cut the parts for the left nacelle on the weekend. Have been experimenting with some formers, before starting to glue. Considering adding formers at the joints of the larger sheets and then cutting these open when
everything is glued in place.

 

[Burnhard]

There is a small progress, finished the two engine nacelles today. EDFs are installed. I am waiting for the electronics to arrive (mainly escs and servos). Will continue with the main fuse and the wing.

I did some testing today whether the EDFs spin backwards. They do. I am wondering whether I should get some bidirectional escs to add reverse thrust.

 

[L Edge]

Let me pass on my assessment when I purchased Freewings 40A and 60 A reversible esc's.
First of all, the time lapse from bringing the throttle to zero and reversing the direction is set for 1 second. Explored it with a 64mm 5 bladed EDF jet and found out that from a 1/4 throttle/zero and 1 second delay it really reversed nicely(due to brake on) and didn't produce much reversed power.

Then tried 1/2 power/ off and 1 second delay and 1/2 power reversed. All kind of noises came from the EDF. I suspected that maybe the brake didn't totally have the EDF come to zero and then being reversed, the blades jumped into reverse and speed up. Now, I have blown blades in flight before and anytime you hear a sudden different sound, one or more blades are gone.

Maybe if you have balanced EDF's, might work. I have seen E-Flite's work on videos, but haven't heard if they have reduced the lifetime of the EDF.
If you do explore, like to hear what has happened.

 

[Burnhard]

Let me pass on my assessment when I purchased Freewings 40A and 60 A reversible esc's.
First of all, the time lapse from bringing the throttle to zero and reversing the direction is set for 1 second. Explored it with a 64mm 5 bladed EDF jet and found out that from a 1/4 throttle/zero and 1 second delay it really reversed nicely(due to brake on) and didn't produce much reversed power.

Then tried 1/2 power/ off and 1 second delay and 1/2 power reversed. All kind of noises came from the EDF. I suspected that maybe the brake didn't totally have the EDF come to zero and then being reversed, the blades jumped into reverse and speed up. Now, I have blown blades in flight before and anytime you hear a sudden different sound, one or more blades are gone.

Maybe if you have balanced EDF's, might work. I have seen E-Flite's work on videos, but haven't heard if they have reduced the lifetime of the EDF.
If you do explore, like to hear what has happened.

Many thanks for sharing!

I have been playing with reverse thrust for a while now on my prop planes. That works reasonably well and I really just use it to cut the roll phase after touch down (other than recently where I hit the switch mid flight but other than some strange noises nothing happened).

My considerations are similar to what you explained. I am a bit hesitant as I fear that there is a good chance to unballlance/ unscrew the fan, which would be fatal. On the other hand, given my normal operations, I can see the thing coming in slow at maybe 1/4 or 1/6 of throttle, reducing throttle, flipping the switch and using the reverse thrust to break.

I ordered two sets of escs so will do some testing to see what happens.