Tomahawk-Design Bae Hawk 1: 3.5
11-15-2015, 04:42 PM
#1229
MIne IS TOMAHAWK also, with a lot of scale adds.. parachute, speedy brake, ordinance, 2 Tailored pilots 1/3, 3 fuel tanks, 2 smoke tanks, smoke pump, powerbox, 4 big batteries, some reinforcements, Jetcat P300
02-03-2016, 07:59 AM
#1238
Thread Starter
@jsnipes:
Check Jörg Schlüters website: http://www.airtech-factory.de/verkau...d-up-displays/
That one is for his A10, but he has made one for his Hawk and he's planning to make several more.
Should be ready within a few weeks.
His email address is [email protected]
Check Jörg Schlüters website: http://www.airtech-factory.de/verkau...d-up-displays/
That one is for his A10, but he has made one for his Hawk and he's planning to make several more.
Should be ready within a few weeks.
His email address is [email protected]
02-03-2016, 08:59 AM
#1239
My Feedback: (3)
Thanks!
@jsnipes:
Check Jörg Schlüters website: http://www.airtech-factory.de/verkau...d-up-displays/
That one is for his A10, but he has made one for his Hawk and he's planning to make several more.
Should be ready within a few weeks.
His email address is [email protected]
Check Jörg Schlüters website: http://www.airtech-factory.de/verkau...d-up-displays/
That one is for his A10, but he has made one for his Hawk and he's planning to make several more.
Should be ready within a few weeks.
His email address is [email protected]
02-07-2016, 01:24 PM
#1240
My Feedback: (35)
Join Date: Apr 2002
Location: Mansfield,
OH
Posts: 190
Likes: 0
Received 0 Likes
on
0 Posts
Hello,
Another Hawk is about to be born. I am wondering what the ideal max flap setup is for normal use. I know the manual says 75mm max and 47 mm for normal use but what does everyone here use?
I have some concern that too much flap could blank out the stab.
Thanks,
Scott
Another Hawk is about to be born. I am wondering what the ideal max flap setup is for normal use. I know the manual says 75mm max and 47 mm for normal use but what does everyone here use?
I have some concern that too much flap could blank out the stab.
Thanks,
Scott
02-08-2016, 09:12 AM
#1242
Thread Starter
Scott,
According Andreas Rupert both setting can be used, but 75 mm is not really necessary.
I'm not sure if stabilzer blanking is the problem: a large landing flap setting requires a steady descent profile , typically 3 degrees, to keep the angle of attack within limits and still sufficient speed.
According Andreas Rupert both setting can be used, but 75 mm is not really necessary.
I'm not sure if stabilzer blanking is the problem: a large landing flap setting requires a steady descent profile , typically 3 degrees, to keep the angle of attack within limits and still sufficient speed.
02-08-2016, 09:48 AM
#1243
Scott please use caution with max flap. There have been a few 1.3 size Hawks recently that were lost to what we believe was too much flap. If you look at the CompArf Skygate thread hear on RCU you will see mine and many other's comments including the British Aerospace Engineering findings on that subject. I have right a 48 degrees of maximum flap and it will travel a lot more than that.
If you do anything more at least get 3 mistakes high and try them but be ready to put them back up if you notice you elevator not responding to your liking.
Best of luck on your maiden.
If you do anything more at least get 3 mistakes high and try them but be ready to put them back up if you notice you elevator not responding to your liking.
Best of luck on your maiden.
02-08-2016, 09:54 AM
#1244
Thread Starter
Agree with you on that Jeff, such a large scale modell should be flown the way it was designed for.
Edit: part of my post was missing
I've called Andreas today and according to them max landing flaps is 75 millimeters at the inside trailing edge and is meant for short field performance.
So a slightly steeper approach with sufficient speed, short flare and hit the brakes.
They demonstrate it regularly.
Edit: part of my post was missing
I've called Andreas today and according to them max landing flaps is 75 millimeters at the inside trailing edge and is meant for short field performance.
So a slightly steeper approach with sufficient speed, short flare and hit the brakes.
They demonstrate it regularly.
Last edited by Remco45; 02-08-2016 at 10:08 AM.
02-09-2016, 07:36 AM
#1246
Thread Starter
@Scott,
Today I've had a lengthy conversation with Tomas Hoechsmann regarding Stabilizer and Flap issues.
Stabilzer issues
He's very clear that they do not have any problems reported, except for one in the beginning.
That crash was the result of no stabilizer control after a short sharp noise was heard.
A possible cause (but could not be determined due to heavy burning) could have been the elevator servo frame which was torn away from the glass cloth/herex sandwich.
There is at least one such report from an Original Skygate Hawk also, but...
...as Marc S has described in his virtual manual over and over again, all woodwork which is glued to the fuselage inside must be givven a nice bead of aeropoxy/Hysol or similar if not done by the factory.
The Tomahawk Design Hawk has a much larger wooden elevator servo frame with a lot more contact surface and such problems have not been reported since as far as he's aware of.
He feels that other stabilizer problems are most likely due to installation issues.
Besides mechanical issues such as oiling of the bearings , making sure the push-pull rod is running smooth etc., he mentioned RC installation.
For example, if an electric gear is operated simultaneously with full flap selection, there's a lot of current drawn which in turn may result in a voltage dip.
Some power managment systems and certain brands of 2.4 GHz receivers do not tolerate voltage dips well and may even re-boot or reset which could take up to 3 seconds.
Flap issues
For demonstrations, he uses a flap setting which is a bit more than 75 mm.
When seen from above, the leading edge of the upper flap vane is just "touching" the rear of the fixed wing.
With this setting he lands on 100 meter fields and has also demonstrated such landings on 75 meter fields.
But like Jeff said, its probably best to learn this aircrafts behaviour at a safe altitude.
Note that large flap setting, typically above 15 - 20 degrees - do hardly provide any more lift, they then mostly provide more drag!
The speed difference of a B737-700 with flaps 15 compared to flaps 30 is just 7 KNOTS meaning you can fly 4.6% slower...
With flaps 40 you can reduce speed another 3 KNOTS, making the total speed reduction a meager 6.7%.
As our 1:3.5 scale models are a lot lighter, we can probably reduce speed a bit more due to the low wing loading, but there's a limit...
Hope this helps.
Today I've had a lengthy conversation with Tomas Hoechsmann regarding Stabilizer and Flap issues.
Stabilzer issues
He's very clear that they do not have any problems reported, except for one in the beginning.
That crash was the result of no stabilizer control after a short sharp noise was heard.
A possible cause (but could not be determined due to heavy burning) could have been the elevator servo frame which was torn away from the glass cloth/herex sandwich.
There is at least one such report from an Original Skygate Hawk also, but...
...as Marc S has described in his virtual manual over and over again, all woodwork which is glued to the fuselage inside must be givven a nice bead of aeropoxy/Hysol or similar if not done by the factory.
The Tomahawk Design Hawk has a much larger wooden elevator servo frame with a lot more contact surface and such problems have not been reported since as far as he's aware of.
He feels that other stabilizer problems are most likely due to installation issues.
Besides mechanical issues such as oiling of the bearings , making sure the push-pull rod is running smooth etc., he mentioned RC installation.
For example, if an electric gear is operated simultaneously with full flap selection, there's a lot of current drawn which in turn may result in a voltage dip.
Some power managment systems and certain brands of 2.4 GHz receivers do not tolerate voltage dips well and may even re-boot or reset which could take up to 3 seconds.
Flap issues
For demonstrations, he uses a flap setting which is a bit more than 75 mm.
When seen from above, the leading edge of the upper flap vane is just "touching" the rear of the fixed wing.
With this setting he lands on 100 meter fields and has also demonstrated such landings on 75 meter fields.
But like Jeff said, its probably best to learn this aircrafts behaviour at a safe altitude.
Note that large flap setting, typically above 15 - 20 degrees - do hardly provide any more lift, they then mostly provide more drag!
The speed difference of a B737-700 with flaps 15 compared to flaps 30 is just 7 KNOTS meaning you can fly 4.6% slower...
With flaps 40 you can reduce speed another 3 KNOTS, making the total speed reduction a meager 6.7%.
As our 1:3.5 scale models are a lot lighter, we can probably reduce speed a bit more due to the low wing loading, but there's a limit...
Hope this helps.
Last edited by Remco45; 02-09-2016 at 07:39 AM. Reason: typo
02-09-2016, 07:49 AM
#1248
"For example, if an electric gear is operated simultaneously with full flap selection, there's a lot of current drawn which in turn may result in a voltage dip."
I would highly recommend using a separate battery for all electric landing just because if this fact! I use a 3s life battery on my Down and Lock conversion.
Remco is dead on I could see this causing a lock out due to voltage when the gear in coming up to the stops.
I carry a total of 5 batteries 2 for the RX and 3 separate batteries on my hawk that power the smoke pump, lights and gear.
I would highly recommend using a separate battery for all electric landing just because if this fact! I use a 3s life battery on my Down and Lock conversion.
Remco is dead on I could see this causing a lock out due to voltage when the gear in coming up to the stops.
I carry a total of 5 batteries 2 for the RX and 3 separate batteries on my hawk that power the smoke pump, lights and gear.
02-09-2016, 08:16 AM
#1249
Thread Starter
Just one more aspect to Large Flap Settings: the CG
I haven't flown my Hawk yet, but a far forward CG (nose heavier) might seem more stable but this can have a negative effect when using large landing flap settings combined with slow speeds.
Because of the forward CG, a change in pitch requires more stabilizer and when flying slow, even more stabilizer is needed for a pitch change.
This combination could mean that the Stabilizer might reach it's stall limit.
Another reason to first test this high enough and when feeling assured, use max land flaps when established on final and in a steady descend with sufficient speed and thrust.
I haven't flown my Hawk yet, but a far forward CG (nose heavier) might seem more stable but this can have a negative effect when using large landing flap settings combined with slow speeds.
Because of the forward CG, a change in pitch requires more stabilizer and when flying slow, even more stabilizer is needed for a pitch change.
This combination could mean that the Stabilizer might reach it's stall limit.
Another reason to first test this high enough and when feeling assured, use max land flaps when established on final and in a steady descend with sufficient speed and thrust.
02-11-2016, 11:57 AM
#1250
I had lunch today with a very experienced and highly qualified engineer who was deeply involved in wind tunnel testing of the Hawk. We discussed pitch down problems and he gave me an explanation, nothing like any of us guessed might be the cause.!
I will write a description when I have a little more time.
David.
I will write a description when I have a little more time.
David.