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First "Flight" and first Crash

Romf

New member
#1
Hello,

I am Robert from Germany and I am just starting in the Hobby.

Today I finished the build of the Tiny Trainer with the polyhedral wings and a Power Pack A (german version from Graupner) and an 3s 850mAh battery. After completing the electronic setup I checked the Center of Gravity and almost dropped the Plane, because it was extremely nose heavy. After Putting the battery as far back as possible the Tiny Trainer still was strongly leaning nosewards .

Despite better knowledge I decided to make an unpowered test throw in the garden...

This first "flight" sent the plane in an almost ballistic trajectory straight in the ground and despite landing on our lawn, broke the prop...
I am a little clueless, what to do about that.

What I found out so far is, that my battery is slightly heavier than the equivalent one recommended in the flitetest store (83g vs 78g) and I have placed the power pod a bit less than half an inch (about 1cm) further to the front than Josh did in his build video. (The reason being that the Graupner motor, that I got, has the cables coming out to the side with strong kink protection and therefore required a bit more space)

All other parts of the plane seem exactly right with all holes matching, etc. the total weight of the plane with trainer wing, battery and electronics is about 290g. (10.2 oz according to google)

What is your experience here? Should I add ballast in the front? Or maybe buy a smaller (2 cell) battery? Help!

Best regards from Germany,
Robert
 

Bricks

Well-known member
#2
Since you are nose heavy you would add weight to the tail. The stiff wires coming out of your motor instead of putting them thru the hole in the firewall run them down under and put another hole in the bottom of the power pod this should let you place the motor back where it belongs, and help with the nose heavy. Are all control surfaces set at zero and did you give it a pretty good throw.
 

Hai-Lee

Old and Bold RC PILOT
#3
I use a larger diameter motor on my versions, (it only JUST fits), and I normally mount the motor so that the wires protrude downwards to under the powerpod. I then cut a small hole in the powerpod, just behind the firewall, and loop the wires back in to the power pod where I locate my ESC. I still use the underside of the powerpod as the battery mounting location.

This allows me to either bring the Powerpod further forward or push it back in as required for the battery I use.

If you are worried about the wires pointing down you can mount the motor so that they stick upwards and make a small cut in the top front of the fuselage to allow the wires to pass into the plane.

Just what works for me!

Have fun!
 

Romf

New member
#4
Thanks for your answers!

@Bricks: I might have been too worried to really give it a good throw. But I guess with the COG definitely off I guess that might have made more damage anyway...

I think I will indeed try to move the Power Pod backwards. Ich will check out your suggestions about the cable routing. Makes sense!

I don't know if having two pairs of holes from the bbq skewers close to each other will be a problem when I move it. Maybe I even have enough scrap pieces of foamboard to build an other power pod... (This stuff is hard to get over here...)

And I will buy a smaller battery, too. I have the impression, that the motor might be a bit strong for me as a beginner with a 3 cell anyway.

I will report any new results as soon, as I get to fly!

Robert
 

d8veh

Well-known member
#5
When you threw it, was your radio gear switched on? If so, what was the position of the elevator?

For a test glide like that, you should set a bit of up elevator and you should throw it over long grass or somewhere where it will have a soft landing.
 

Hai-Lee

Old and Bold RC PILOT
#8
Thanks for your answers!

@Bricks: I might have been too worried to really give it a good throw. But I guess with the COG definitely off I guess that might have made more damage anyway...

I think I will indeed try to move the Power Pod backwards. Ich will check out your suggestions about the cable routing. Makes sense!

I don't know if having two pairs of holes from the bbq skewers close to each other will be a problem when I move it. Maybe I even have enough scrap pieces of foamboard to build an other power pod... (This stuff is hard to get over here...)

And I will buy a smaller battery, too. I have the impression, that the motor might be a bit strong for me as a beginner with a 3 cell anyway.

I will report any new results as soon, as I get to fly!

Robert
When I have the need for two positions for the powerpod I do NOT use the same holes in the fuselage for both positions as this can make the power pod holes too close together. I normally make a fresh pair of hole in both the fuselage and the powerpod so that I have plenty of meat around the skewers when in place.

An additional benefit of the extra pair of holes is that I can see at a quick glance which battery I am currently setup to use!

Just what works for me!

have fun!
 

buzzbomb

I know nothing!
#9
You might also try simply strengthening the area where the skewers go through. Just something like gift card pieces glued to support the area. Drill the hole (I did the first with a pair of pliers and a drill bit) and the plastic supports the foam.

Here's pics of what I'm talking about. If the the link takes you to the top, just scroll down a bit.
https://forum.flitetest.com/index.php?threads/my-tiny-trainer-build.55683/

Edit: I should clarify that this was not my idea. I got it from this forum.
 

donalson

Active member
#10
on my original tiny trainer I had to mount the battery to the bottom bottom section, not under the power pod... it worked well...

I've sense changed over to a different fuse design that is lighter and easier to build and tossed in a 2208 1400kv (something between an F pack and B pack motor... cost about 20g between the esc and motor but more powerful and more efficient...

also for power packs... I found the minis to be very prone to killing holes quickly... on my bigger stuff I do the gift card supports... but on these I just do a light stripe of hot glue on each side to support the power pod...
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#12
I second the question about your flight control surfaces.

Nose heavy blows but to really trash your trainer, reverse the flight controls so that when you pull back on the stick, your plane nose-dives...
 

Romf

New member
#13
Hi,

my control surfaces were in neutral position (as good as I could trim them before flight...) and my controls were not reversed either (I double checked on that!)

So the first thing I will do (when I find some time to get in my workshop...) is to do something about the COG. And I ordered a lighter 2 cell battery (50g vs 83g).

The reinforcement many of you recommend seems a pretty good idea and I will implement those, too.

Thanks for your many answers!

Regards,
Robert
 

Romf

New member
#14
Short update:
The lighter Battery and some added reinforcements (=extra weight) on the tail and better cable management (= components are located slightly more torwards the tail) brought some improvement of the COG.

I made a little stand to determine the position of the COG. See pictures before and after the modifications:
IMG_0161.jpg

and after:
IMG_0163.jpg

Almost there ...
 

kilroy07

Well-known member
#17
To help my CG, I just added another velcro strip to the bottom of the fuselage
Ditto here, my batteries are too wide to fit under the pod anyway.

I see no serious damage, the Tiny Trainer is a great beginner. Stick with it, we are here to help.

And Welcome to the community!
 

donalson

Active member
#19
Hello, To help my CG, I just added another velcro strip to the bottom of the fuselage, and moved the battery almost to the oval hole. (see attached) Looks odd, but balances well, and battery changes are very easy. View attachment 118623
that is where I had to mount mine... I looped a rubber band around it (catching to the wing bbq sticks)... just a little extra insurance to help keep the lipo on the velro...
 

Romf

New member
#20
Hi,

having the battery at a position that is very likely to hit the ground at one time or another seems a bit risky...

Has anyone tried to put the battery on TOP of the plane?

I have meanwhile managed to place the battery at about the same spot but inside the fuselage. Now my TT has a good balance (and the test throw went very well this time!). Unfortunately this means that it takes some time and effort, to disconnect the battery or to swap it.

- Robert