Trim f86 First Flight
12-25-2002, 07:13 AM
#1
Trim f86 First Flight
Merry Christmas to all, and a happy new year.
I write u today to tell you about my maiden flight with my Trim f86, which also is my first ducted fan flight.
I can call it a success because I didn’t crash, and returned home safely. But the flight was a failure otherwise.
Here is what happened: (I ll try to make this as short as possible)
When attempting my first take off, the model couldn't reach takeoff speed, so I aborted and tried again with a more lean needle setting.
On the second attempt, same thing but this time I decided to run even more.
I took off when the model started to bounce due to a slightly bumpy runway.
The plane never seemed to reach a good speed and struggled to stay in the air.
The nose kept coming down and I applied max. flap to help it get up. At one point, I was holding max. Up elevator just to keep the plane from hitting the ground.
I managed (some how) to return to the runway and land it safely.
Please note:
1- My model weighs 6 kilos (13 pounds) which is well within the limits specified by the manufacturer.
2- The engine is a new OS91, properly broken-in.
3- The needle setting was to the maximum. (the engine was screaming, I had to wear an ear plug)
4- There is no leak in the internal duct. Even the small hole where I access the spark plug has been closed. (The thrust is tremendous).
5- I used 10% Byron fuel.
6- The distance I ran the model before takeoff was approx. 350-400 feet.
I don’t know what to do. Maybe I should have gone straight to turbines.
What do you think was the problem?
I write u today to tell you about my maiden flight with my Trim f86, which also is my first ducted fan flight.
I can call it a success because I didn’t crash, and returned home safely. But the flight was a failure otherwise.
Here is what happened: (I ll try to make this as short as possible)
When attempting my first take off, the model couldn't reach takeoff speed, so I aborted and tried again with a more lean needle setting.
On the second attempt, same thing but this time I decided to run even more.
I took off when the model started to bounce due to a slightly bumpy runway.
The plane never seemed to reach a good speed and struggled to stay in the air.
The nose kept coming down and I applied max. flap to help it get up. At one point, I was holding max. Up elevator just to keep the plane from hitting the ground.
I managed (some how) to return to the runway and land it safely.
Please note:
1- My model weighs 6 kilos (13 pounds) which is well within the limits specified by the manufacturer.
2- The engine is a new OS91, properly broken-in.
3- The needle setting was to the maximum. (the engine was screaming, I had to wear an ear plug)
4- There is no leak in the internal duct. Even the small hole where I access the spark plug has been closed. (The thrust is tremendous).
5- I used 10% Byron fuel.
6- The distance I ran the model before takeoff was approx. 350-400 feet.
I don’t know what to do. Maybe I should have gone straight to turbines.
What do you think was the problem?
12-25-2002, 08:55 AM
#2
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Trim f86 First Flight
Hi Sabre,
Kol Aam wa enta be kheir for the Eid El Kebir, a bit late for wishes as usual.
To me it sounds like you have a very nose heavy jet here. Check your C.G. as well as your wing and tail incidenses.
Also, don't expect DF's to have a tremendous ground speed, they will only unwind in the air.
BRG,
Chris
Kol Aam wa enta be kheir for the Eid El Kebir, a bit late for wishes as usual.
To me it sounds like you have a very nose heavy jet here. Check your C.G. as well as your wing and tail incidenses.
Also, don't expect DF's to have a tremendous ground speed, they will only unwind in the air.
BRG,
Chris
12-25-2002, 09:46 AM
#3
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Trim f86 First Flight
What was the temp and how high is you field above sea level? It's been over ten years ago but I recall Kuwait getting a little warm now and then.. Thrust goes way down at high density altitudes. You might try it just after sunrise when it's cool.
Also check the fan rotor is not slipping on the shaft. You can paint a white stripe across the spinner and tac it. You should be getting 20,000 RPM or so with a RAMTEC fan.
Something is wrong - so don't try to force it off the ground until it's fixed.
Good luck
Also check the fan rotor is not slipping on the shaft. You can paint a white stripe across the spinner and tac it. You should be getting 20,000 RPM or so with a RAMTEC fan.
Something is wrong - so don't try to force it off the ground until it's fixed.
Good luck
12-26-2002, 02:17 AM
#4
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Trim f86 First Flight
Sabre,
My Trim Sabre (2 before I lost one) gets off grass in about 200 feet and climb out with a surprising amount of authority for a fan. Something doesn't sound right.
One thing to be aware of. At full flap, the nose will pitch down, not up as you might expect. I have a mix set up on my radio to give some UP elevator when the flaps pass about the 60% travel mark. For takeoff, I only use about 15 degrees flap.
Double check the cg as well as the incidence of the stabs. If the jet is nose heavy you will need a lot of up to compensate. This, in turn, increases drag and slows the model down making it handle like crap.
Regards,
Garrett
My Trim Sabre (2 before I lost one) gets off grass in about 200 feet and climb out with a surprising amount of authority for a fan. Something doesn't sound right.
One thing to be aware of. At full flap, the nose will pitch down, not up as you might expect. I have a mix set up on my radio to give some UP elevator when the flaps pass about the 60% travel mark. For takeoff, I only use about 15 degrees flap.
Double check the cg as well as the incidence of the stabs. If the jet is nose heavy you will need a lot of up to compensate. This, in turn, increases drag and slows the model down making it handle like crap.
Regards,
Garrett
12-26-2002, 08:07 AM
#5
Trim f86 First Flight
Hi,
Maybe this is a dumb question, but were you running 10% Byron DUCTED FAN fuel? If not, I can imagine that your engine is running too lean, or at least too hot. You said that the needles were set to "maximum". What exactly does that mean? If it means it was set to maximum RPM, then you definitely have a problem. Unless you're using an inflite mixture (you didn't mention either way), you probably shouldn't be running the engine at max RPM. If you do that, don't expect it to last for very long. Can you elaborate on your engine settings and fuel?
Maybe this is a dumb question, but were you running 10% Byron DUCTED FAN fuel? If not, I can imagine that your engine is running too lean, or at least too hot. You said that the needles were set to "maximum". What exactly does that mean? If it means it was set to maximum RPM, then you definitely have a problem. Unless you're using an inflite mixture (you didn't mention either way), you probably shouldn't be running the engine at max RPM. If you do that, don't expect it to last for very long. Can you elaborate on your engine settings and fuel?
12-28-2002, 05:25 PM
#6
Trim f86 First Flight
Yellowaircraft
First of all, I m sorry I mentioned the fuel in my thread. I didn’t know what to say.
Second, maximum setting means needle setting or rpm.
The way I set the needle is by closing it until rpm doesn’t increase. Then I open the needle ¼ turn I use the smoke as a second indicator. Don’t know how to measure rpm, my tach. Is for 2 or 3 blade props.
I assume you took the time to reply cause you want to help.
As a senior member, Can you illaborate more on needle setting (remote), using flaps, or any thing that can help a beginner like me.
Cairoman,
Thanks, the model was nose heavy especially when full of fuel.
I relocated the fuel tanks atop the CG. And moved the battery back a little.
What I should have mentioned was, taking off from sand. It is hard compact sand with a few soft patches. I think that slowed it down a little.
First of all, I m sorry I mentioned the fuel in my thread. I didn’t know what to say.
Second, maximum setting means needle setting or rpm.
The way I set the needle is by closing it until rpm doesn’t increase. Then I open the needle ¼ turn I use the smoke as a second indicator. Don’t know how to measure rpm, my tach. Is for 2 or 3 blade props.
I assume you took the time to reply cause you want to help.
As a senior member, Can you illaborate more on needle setting (remote), using flaps, or any thing that can help a beginner like me.
Cairoman,
Thanks, the model was nose heavy especially when full of fuel.
I relocated the fuel tanks atop the CG. And moved the battery back a little.
What I should have mentioned was, taking off from sand. It is hard compact sand with a few soft patches. I think that slowed it down a little.
01-27-2004, 12:40 PM
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RE: Thanks to RCuniverse
Hows it going now?
I've just got my first Trim F-86. OS91/ramtec/mini pipe.
The plane's a beast. Will hope to fly it in a few months!
Dave
the photo is of my F-86 next to my tiddly HB A7 (which now has Kress rk-740 and picco 45)
I've just got my first Trim F-86. OS91/ramtec/mini pipe.
The plane's a beast. Will hope to fly it in a few months!
Dave
the photo is of my F-86 next to my tiddly HB A7 (which now has Kress rk-740 and picco 45)
01-27-2004, 01:09 PM
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RE: Trim f86 First Flight
got to get my A7 ready to fly and Got to restore an Aerobatic plane. Then install the engine/fan into the '86, install the nose retract. Find my way around the thing. then eventually fly it!
Will be a few months
But thats ok, got plenty to get on with
Dave
Will be a few months
But thats ok, got plenty to get on with
Dave
01-27-2004, 01:29 PM
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RE: Thanks to RCuniverse
Sabre,
If it's of use, here's the best way I've found to test the mixture strength on a D/F engine:
Set the throttle at max and wind in the needle valve until the engine 'comes on the pipe' - you can't miss this, it suddenly speeds up and runs 'smoother' - then momentarily (and I mean a blink of the eyelid moment) pinch the fuel feed tube between thumb and forefinger and, if the mixture's right, you should get a momentary rise in RPM. If the mixture's too lean, the engine will cut and, if it's too rich you'll notice no difference. If you think the mixture's right, also check that the engine's still smoking a little - insurance that there's still oil being burnt!
Also, just in case you're not familiar with it, you may need need to 'set up' the idle end of the carburettor too (if it idles unevenly or if the transition from idle to max is 'lumpy'). First off, set the max mixture, as described above, then set the throttle to idle and alter the idle mixture screw (in middle of throttle barrel) until the engine idles smoothly and transitions from idle to max smoothly too.
The wrong plug can affect the engine's performance too - for my OS .91 VR/DFs I found the McCoy (#9, I think) D/F plug was the best...some guys use OS #8 and others Rossi...both with success.
Hope this helps.
Cheers,
Dick
If it's of use, here's the best way I've found to test the mixture strength on a D/F engine:
Set the throttle at max and wind in the needle valve until the engine 'comes on the pipe' - you can't miss this, it suddenly speeds up and runs 'smoother' - then momentarily (and I mean a blink of the eyelid moment) pinch the fuel feed tube between thumb and forefinger and, if the mixture's right, you should get a momentary rise in RPM. If the mixture's too lean, the engine will cut and, if it's too rich you'll notice no difference. If you think the mixture's right, also check that the engine's still smoking a little - insurance that there's still oil being burnt!
Also, just in case you're not familiar with it, you may need need to 'set up' the idle end of the carburettor too (if it idles unevenly or if the transition from idle to max is 'lumpy'). First off, set the max mixture, as described above, then set the throttle to idle and alter the idle mixture screw (in middle of throttle barrel) until the engine idles smoothly and transitions from idle to max smoothly too.
The wrong plug can affect the engine's performance too - for my OS .91 VR/DFs I found the McCoy (#9, I think) D/F plug was the best...some guys use OS #8 and others Rossi...both with success.
Hope this helps.
Cheers,
Dick
01-27-2004, 07:41 PM
#13
RE: Trim f86 First Flight
You can paint a white stripe across the spinner and tac it. You should be getting 20,000 RPM or so with a RAMTEC fan
01-27-2004, 09:55 PM
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RE: Trim f86 First Flight
ORIGINAL: rcFLYBOY14
Can someone please elaborate on this? I was wondering how to measure fan rpm...[:-]
You can paint a white stripe across the spinner and tac it. You should be getting 20,000 RPM or so with a RAMTEC fan
01-28-2004, 02:16 AM
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RE: Trim f86 First Flight
ORIGINAL: Shrike builder
Dick,
thx for the tip ;-) my os91/ramtec is waiting for me ! plan to fire it up this year...
Dick,
thx for the tip ;-) my os91/ramtec is waiting for me ! plan to fire it up this year...
Shrike,
When you get your jet model airborne, why don't you come across the Channel to a few of our Jet Meets? (one of your fellow countrymen is a regular at my Classic Jets events). Drop me a pm with your email address and I'll make sure you get an invite. Where abouts in France are you?
Cheers,
Dick
